PB85-124899
Review of In-Place Treatment Techniques for Contaminated Surface Soils
Volume 2:  Background  Information for  In Situ Treatment
Utah State University
Logan,  Utah
Nov 84
                     U.S. DEPARTMENT OF COMMERCE
                  National Technical Information Service
                                    NT1S

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                                                PROPERTY OF THE
U.S. Environmental Protection Agency              OFFICE Fsuf$fjfU
Region 5, Library (PL-12J)                             cPA-540/2-84-003b
77 West Jackson Boulevard, 12th Floor                  November
Chicago, IL 60504-3590 -
                REVIEW OF IN-PLACE TREATMENT TECHNIQUES
                    FOR CONTAMINATED SURFACE SOILS

        Volume 2:  Background Information for In Situ Treatment
                                  by

          Ronald C. Sims, Darwin L. Sorensen, Judith L. Sims,
           Joan E.  McLean, Ramzi Mahmood, and R. Ryan Dupont
                         Utah State University
                           Logan, Utah 84322'
                                  and
                            Kathleen Wagner
                            JRB Associates
                        McLean, Virginia  22102
                        Contract No. 68-03-3113
                            Project Officer

                             Naomi  Barkley
              Solid and Hazardous Waste Research Division
              Municipal Environmental  Research Laboratory
                        Cincinnati, Ohio 45268
              MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
                  OFFICE OF RESEARCH AND DEVELOPMENT
                 U.S.  ENVIRONMENTAL PROTECTION AGENCY
                        CINCINNATI, OHIO 45268


                        REPRODUCED BY
                        NATIONAL TECHNICAL
                        INFORMATION SERVICE
                            US DEPAR'MiNl OF COMMfRCE
                             SPfWGfiElD VS. 22161

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THCHNICAL REPORT DATA
'P'.ssst rtsd Instrjcr.cns on she rtvtne sefare zomt
i. 3S=ORT NO. 2.
EPA-540/2-84-003b
*. TfTLS ANO SUSTITi.
REVIEW OF IN-PLACE TREATMENT TECHNIQUES FOR
CONTAMINATED SURFACE SOILS - VOLUME 2: BACKGROUND
INFORMATION FOR IN-SITU TREATMENT
7. AUTHORIS)
Ronald Sims
9. ?ai=Ofl.V)ING ORGANISATION NAME ANO AOORS53
Utah Water Research Laboratory
Utah State University
Loqan, Utah ' 84322
12. SPONSORING AGENCY NAME ANO ADDRESS
Municipal Environmental Research LaboratoryGin. , OH
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. SUPPLEMENTARY NOTES
Naomi P. Barkley 513/684-7875
we::n%i
2. 3C:?>eN-r 3 -iCC333'G OeSCfllPTOflS

18. 01STRI3UTIOM STATSMe.NT
RELEASE TO PUBLIC
b.lO6NT1PlSaS/CPSN SNO6O TS3MS

19. SECURITY CLASS tnia Xeporn
UNCLASSIFIED
20. sscoRiTY CLASS , r;i pu?/
UNCLASSIFIED
C. COSAT' - t c C.C'-r

21. .NO. :- -Z^'
389
:; a<^ics
f PA form 2220-1 iR. 4-77)   f*eviou> ac now 11 3 aiOu-E

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                                   DISCLAIMER


     The information  in  this  document  has  been  funded  wholly or  in  part  by  the
United States  Environmental  Protection  Agency  under  Contract No.  68-03-3133
(Task 41)  to JRB Associates  with a  subcontract  to  the  Utah Water  Research
Laboratory,  and Contract No.  68-01-6160  (Work  Order 12) to Arthur  D. Little,
Inc.    It has  been  subject  to  the Agency's  peer  and  administrative  review
and has  been  approved for publication.   The contents  reflect  the views  and
policies of the Agency.   Mention  of  trade  names  or  commercial  products does
not constitute endorsement  or recommendation for use.
                                      n

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                                   FOREWORD
     The  U.S.  Environmental   Protection  Agency  was created  because of  in-
creasing public and government concern about the  dangers  of pollution to the
health  and  welfare of  the  American  people.   Noxious  air,  foul  water,  and
spoiled  land are  tragic testimonies to the  deterioration  of our  natural
environment.    The complexity  of  that environment  and  the interplay of  its
components require a  concentrated  and  integrated attack on the problem.

     Research and development constitute  that necessary first  step in problem
solution, and  they involve  defining  the  problem,  measuring its  impact,  and
searching  for  solutions.   The  Municipal  Environmental  Research  Laboratory
develops new and  improved technology and systems to prevent, treat, and manage
wastewater and solid  and  hazardous  waste  pollutant  discharges  from municipal
and community sources, to preserve and treat  public  drinking  water supplies,
and to minimize the adverse economic,  social, health, and aesthetic effects of
pollution.  This  publication  is one of the products of that research and is a
most vital communications link between the researcher and  the  user community.

     Contaminated soils  present one of the  most  significant problems  of
uncontrolled  hazardous waste  sites.    This report  presents  a review of avail-
able information  on in-place  treatment techniques applicable to remediation of
hazardous waste-contaminated  surface soils.
                                  Francis T. Mayo
                                  Director
                                  Municipal Environmental Research Laboratory

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                                  ABSTRACT


     This second volume  of a two  volume manual  on in-place treatment of
hazardous waste contaminated  soil  supports the treatment methodology described
in Volume  1  (EPA-540/2-84-0032).   The  information presented  on  monitoring
to determine   treatment  effectiveness,  characterization  and   evaluation  of
the behavior  and  fate of  hazardous  constituents in soil/waste  systems,  and
properties (including adsorption, degradation,  and volatilization parameters)
for various compounds is  intended  to help  the  manual  user  in making  more
complex decisions and in selecting  analyses  concerning  site,  soil,  and waste
interactions.

     This report was  submitted in partial fulfillment  of Contract  No. 68-03-
3113  by Utah State University under the sponsorship of the U.S. Environmental
Protection Agency.   The report  covers  the  period  December  1982  to  December
1984  and work  was completed  as  of January 1984.
                                       IV

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                                   CONTENTS
FOREWORD
ACKNOWLEDGMENTS
ABSTRACT
LIST OF FIGURES
LIST OF TABLES

SECTION 1 - INTRODUCTION

SECTION 2 - MONITORING

            Introduction
            Statistical Considerations
            Soils Sampling in the Treatment Zone and in the
              Underlying Unsaturated Zone
            Soil  Pore Liquid Sampling in The Unsaturated Zone
            Water Samples from the Saturated Zone
            Runoff Water Monitoring
            Air Monitoring
            References

SECTION 3 - CHARACTERIZATION AND EVALUATION OF FUNDAMENTAL
              PROCESSES IN SOIL/WASTE SYSTEMS

            Site and Soil Factors Related to In Situ Treatment

                 Introduction
                 Site Characterization Related to Off-site
                   Migration
                 Site Characteristics with Regard to In Situ
                   Treatment Techniques
                 Site Characterization Related to Physical
                   Execution of In Situ Treatment Technology

                 Sources of Information

            Waste Characterization Related to In Situ Soil Treatment

                 Introduction
                 Definition of Hazard and Degree of Hazard
                 Preliminary Waste Identification
 2
 2

 3
 5
 6
 7
10
11
13

13

13

15

61

61

62

63

63
64
68

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                 CONTENTS (Continued)
     Chemical  Analysis of the Wastes                            69
     Waste Characteristics Related to Soil Treatment            70
     Statistical  Considerations                                 73

Immobilization of Chemical Constituents as Related to
  In Situ Treatment                                             73

     Inorganics                                                 73
     Fate of Metals in Soils                                    78
     Solution Chemistry                                         80
     Solid Phase  Formation                                      81
     Heavy Metal  Complexation in Soil Solution                  82
     Computer Simulation of the Soil Solution                   87
     Solid-aqueous Interface Exchange (Outer
       Sphere Complexes)            -                            88
     Specific Adsorption (Inner Sphere Complexes)               89
     Factors Affecting Sorption                                 89
     Oxidation-reduction                                        95

Soil Sorption - Organics                                       107

     Ionic Compounds                                           112
     Nonionic Compounds                                        119
     Quantitative Description of Adsorption                    125
     Factors Affecting Sorption                                134

Soil Microbiological Factors Related to In Situ
  Treatment                                                    138

     The Soil Microbial Ecosystem                              138
     Biogeochemistry of Toxic Metals and Metalloids            144
     Decomposition of Xenobiotic Organic Compounds             148

Quantitative Description of Organic Decomposition              157

     Initial Concentration                                     160
     Temperature                                               160
     Moisture Content                                          166

Chemical Reactions in the Soil Matrix                          167

     Introduction                                              167
     Effects of Waste Type on Soil Properties                  168
     Desorption                                                175
     Soil Catalysis                                            178
     Polymerization                                            180
                           VI

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                 CONTENTS (Continued)
Modeling the Behavior of Waste Constituents in
  Soil Systems                                                  180

     Transport Models                                           180
     Limitations                                                187

Atmospheric Aspects of In Situ Treatment:
  Volatilization and Photodegradation                           190

     Volatilization of Organics                                 190
     Factors Controlling Contaminant Volatilization             202
     Compound Photoreactivity                                   204

References                                                      212

Appendix A.  Parameters for Assessing Soil/Waste
  Interaction                                                   246

Appendix B.  Glossary                                           358

Copyright Notice                                                365
                          VI 1

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                                    FIGURES


                                                                          Page

           Processes influencing the migration of hazardous con-
             stituents in  the terrestrial  environment                       14

3-2        USDA soil textural classification                                 26

3-3        A hypothetical  soil  profile illustrating the common soil
             horizons                                                       31

3-4        Diagrammatic definition and location of various types of
             soil  structure                                                 35

3-5        Weathering pathways  which take  place under moderately acid
             conditions common  in humid temperature regions                 38

3-6        General  relationship between particle size and kinds of
             minerals present                                               39

3-7        (a)  Single silica tetrahedron,   (b) Sheet structure of
             silica tetrahedrons arranged  in  a hexagonal  network            40

3-8        (a)  Single octahedral unit,  (b) Sheet structure of
             octahedral units                                               40

3-9        Sketch  showing  an edge view of  the crystal structure of
             a  1:1  and a 2:1 type clay mineral                              41

3-10       Relationships in mineral  soils  between pH and  the activity
             of microorganisms  and the availability of plant nutrients      46

3-11       Soil-water characteristic curves for several soils               50

3-12       Typical  water-holding capacities of different  textured soils     51

3-13       Frequency of occurrence of inorganic constituents in soil
             at FIT sites                                                    77

3-14       Principal controls on free trace metal concentrations in
             soil  solutions                                                 80

3-15       The  solubility of various lead  oxides, carbonates, and
             sulfates when S0|- and Cl~ are 10"3 M and C02 is 0.003
             atm or as specified                                            83
                                      vm

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                         LIST OF FIGURES (Continued)


                                                                          Page

3-16       The solubility diagram for Pb in Nibley clay loam soil           83

3-17       The solubility diagram for Cd in Nibley clay loam soil           84

3-18       Breakthrough curves for Cd as affected by Cl~ and CIC^' ions     85

3-19       Breakthrough curves for Cu as affected by Cl~ and C104" ions     86

3-20       Breakthrough curves for Ni as affected by Cl~ and C104" ions     86

3-21       Solubility of CuO as a function of log  H+  (25C., I = 0,
              log PC02 = -3-52)                                             87

3-22       The pH-dependent speciation of Cd in: (a) the absence of
             organic ligands Ox, and (b) the presence of 3.5 x 10~4
             M Ox                               -                            92

3-23       Cadmium binding as a function of pH                              93

3-24       Cu2+ adsorption isotherms on Lansing and Mardin A horizon
             soils in the absence and presence of 0.01M CaCl2               94

3-25       Langmuir adsorption isotherm for Cu2+ adsorption on the
             Lansing A soil                                                 96

3-26       Typical adsorption isotherm for metals and soil                  96

3-27       Nickel sorption by Glendale soil, 0.01N CaCL2                    97

3-28       Zero point of charge (pzc) on an iron hydrous oxide             101

3-29       Eh-pH diagram of Cr species in water at 25C calculated         102

3-30       Sorption of Cr(VI) on NaOH-extracted soil                       102

3-31       Concentration of Cr(III) in 24-hour equilibrium solutions
             as a function of pH (HCl-CaC03) and presence of Marlow
             Ap soil                                                       103

3-32       The amount of As(V) removed from DuPage leachate solutions
             by kaolinite and montmori1lonite at 25C plotted as a
             function of pH                                                105

3-33       Diagram showing distribution of forms of As(V)                  105

3-34       The amount of As(III) removed from DuPage leachate solutions
             by kaolinite and montmorilloriite at 25C plotted as a
             function of pH                                                107

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                         LIST OF FIGURES (Continued)


                                                                          Page

           Stable fields of selenium                                       108

           The amount of Se(IV)  removed from DuPage leachate solutions
             by kaolinite and montmorillonite at 25C, plotted as a
             function of pH                                                109

3-37       Solubility diagram for the ferric selenites, and the
             solubility data obtained from 1:10 soil-O.OlM Ca (1^3)2
             extracts of several soils                                     110

3-38       Effect of pH on adsorption of four related s-triazines
             on (top) Na-montmori 11 on ite and (bottom) soil organic
             matter                                                        115

3-39       Classification of adsorption isotherms                          128

3-40       Isotherms for adsorption  of several  cationic pesticides
             on (top) Na-montmori llonite,  (center)  Na-kaol in ite,
             (bottom) soil organic matter                                   128

3-41       Extent of sorption as a function of soil moisture 9 and kj      131

3-42       Linear transforms of  adsorption isotherms                        134

3-43       Errors introduced by  the  assumption that adsorption
             desorption isotherms are singular when they are
             nonsingular                                                   138
3-44       Evolution of   C02 from Core Creek soil  suspensions
             amended with [^Cjmalathion                                 152
3-45       Evolution   CQ,, from tobacco field soil  suspensions             152

3-46       Schematic description of "two compartment" model                160

3-47       Disappearance of total  chemical  for different sizes of
             bound residue reservoir, i.e., k^ (binding)/k_i
             (unbinding) = R                                               161

3-48       Rates of transformation of PNA compounds in soil as a
             function of initial soil concentration                        162

3-49       Effect of climatic conditions at major refinery locations
             on the annual pattern of oil decomposition                    167

3-50       Influence of exchangeable sodium percentage on the
             hydraulic conductivity of a clay loam                         172

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                         LIST OF FIGURES (Continued)


                                                                          Page

           Desorption of fensulfothion from four soils                     177

           Desorption of fensulfothion sulfide from four soils             178

           Soil-water characteristic  relating the volumetric  water
           content 0 to the matric potential  4>m                            182

3-54       Frequency distribution of  values of the pore-water
             velocity for a class length of 10 cm day~l                    182

3-55       Frequency distribution of  values of the apparent diffusion
             coefficient D for a class length of 20 cm? dayl              182

3-56       Calculated relative effluent concentrations for a
             nonadsorbed solute                                            189

3-57       Fraction of contaminant remaining  versus dimensionless
             time                                                          198
                                      XI

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                                    TABLES


Table                                                                     Page

2-1        Requirements of a Complete Monitoring Program                     3

2-2        Equipment for Field Collection of Soil Samples                    4

2-3        Soil-Pore Liquid Sampling Devices                                 6

2-4        Groundwater Sampling Methods                                      7

2-5        Cost Estimates for Various Monitoring Techniques and
             Construction Methods in the Zone of" Saturation                  8

3-1        Landforms and Topography of Hazardous Waste Sites as
             Related to Potential for Migration of Hazardous
             Constituents                                                    16

3-2        Site and Soil Characteristics Identified as Important
             in In Situ Treatment                                            19

3-3        Major Divisions, Soil Type Symbols, and the Descriptions
             for the Unified Soil Classification System (USCS)               20

3-4        Descriptions of Soils in the Highest (Most General)
             Categories of the Present USDA Classification System            22

3-5        Orders in the Present USDA Soil Classification System and
             Approximate Equivalents in the 1938 USDA System                 25

3-6        U.S. Department of Agriculture (USDA) and Unified Soil
             Classification System  (USCS) Particle Sizes                     26

3-7        Corresponding USCS and USDA Soil Classifications                  27

3-8        Corresponding USDA and USCS Soil Classifications                  28

3-9        Information That Can  Be  Inferred from the USDA Soil
             Classification System, Using the Order Mollisol as
             an Example                                                      30

3-10       Suitability of  Various Textured Soils for Land Treatment
             of Hazardous  Industrial Wastes                                  34
                                       xi

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                          LIST OF TABLES (Continued)


Table


3-11       Average Mineralogical Composition of Igneous and
             Sedimentary Rocks                                               37

3-12       The Size, Number, and Surface Area of Soil Particles              38

3-13       Summary of Characteristics of Soil Colloids                       42

3-13a      Oxygen-Containing Functional Groups in Humic Substances           44

3-14       Succession of Events Related to the Redox Potential
             Which Can Occur in Waterlogged Soils, or Poorly
             Drained Soils Receiving Excessive Loadings of
             Organic Chemical Wastes or Crop Residues                        47

3-15       Essential Elements for Biological Growth                          48

3-16       Permeability Values for Soils Classified  in the Unified
             Soil Classification System                                      53

3-17       Factors Affecting Erosion of Soil by Wind                         57

3-18       Important Receiver Characteristics                                60

3-19       Maximum Concentration of Contaminants for Characteristic
             of EP Toxicity                                                  65

3-20       Method for Determination of Microbial Toxicity of a
             Waste/Soil Mixture                                              68

3-21       Types of GC Detectors                                             70

3-22       Methods for Analyzing Waste Constituents  Important to
             In Situ Treatment                                               71

3-23       Soil-Based Waste Characterization                                 74

3-24       Basic Statistical Terminology Applicable to Sampling
             Plans for Solid Wastes                                          75

3-25       List of Inorganic Priority Pollutants                             77

3-26       Percent Occurrence of Inorganics in Soils--Superfund
             and Nonsuperfund sites                                          78

3-27       Content of Various Elements in Soils (Lindsay 1979)
             and in Fit Sites                                                79
                                       XT 1

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                          LIST OF TABLES (Continued)


Table                                                                     Page

3-28       Industrial  Use of Selected Metals                                79

3-29       Some Probable Bivalent Metal Complexes with Inorganic
             Ligands in Soil Solutions                                      85

3-30       Estimated Values of Log ciq and Log c<2                          88

3-31       Stability Constants for Cl Complexes to Ni(II), Cu(II),
             and Cd(II)                                                     91

3-32       Overall Stability Constants of Cd Complexes                      92

3-33       Effect of pH on Probable Solution Percent Composition
             of Different Ion Species                                       94

3-34       Calculated  Langmuir Parameters from Soil Adsorption
             of Cu2+ and Cd?+                                               97

3-35       Freundlich  Parameters and Correlation Coefficients for
             Sorption  of Ni in 0.01N CaCl2 by 12 Soils                      99

3-36       Freundlich  Parameters for Sorption of Ni in Different
             Ca Solutions by Four Soils                                     99

3-37       Freundlich  Parameters for Sorption of Zn in 0.01N CaCl2
             by the Soils Studied                                           100

3-38       Percent of  Applied Hg Evolved from Soils Within 144
             Hours                                                          104

3-39       Properties  of Basic Pesticides                                   113

3-40       Properties  of Cationic Pesticides                                117

3-41       Properties  of Acidic Pesticides                                  118

3-42       Selected Properties of Some Nonionic Pesticides                  120

3-43       Equilibrium and Nonequilibrium Models                            126

3-4/l       Koc Relationships with Solubility and Octanol-Water
             Partition Coefficient                                          133

3-45       Selected Physical Properties of Soil Constituents                136

3-46       Persistence of Polynuclear Aromatic Hydrocarbons  in
             Natural Waters                                                 153
                                       xiv

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                          LIST OF TABLES (Continued)


Table                                                                     Page

3-47       Pesticides Included as Constituents of Hazardous Waste           154

3-48       Kinetic Parameters Describing Rates of Degradation of
             Aromatic Compounds                                             163

3-49       Industrial Categories Generating Acidic Waste Constituents       169

3-50       Effect of Organic Acids on Clay Solubility                       170

3-51       Classification of Salt-Affected Soils                            171

3-52       Critical SAR Values for Soil                                     172

3-53       Response of Soil Microbial Populations to Application of
             Solvents                                                       172

3-54       Dielectric Constants, Densities and Water Solubilities
             of Various Halogenated and Nonhalogenated Solvents             174

3-55       Effect of Organic Solvent in Clay Permeability                   174

3-56       Sorption of Halogenated Organics on Soil and Clay                175

3-57       Adsorption of Surfactants on Montmorillonite                     176

3-58       Properties of Soil Adsorbents                                    177

3-59       Boundary Conditions for the Transport Equation                   183

3-60       Representative Values of Hydraulic Parameters                    189

3-61       Hazardous Chemical Vapors Detected at Uncontrolled
             Hazardous Waste Sites                                          191

3-62       Pesticide Photochemical Reactions in the Vapor-Phase             208

3-63       Rate Constants for the Hydroxide Radical Reaction  in
             Air with Various Organic Substances, KQH in  Units of
              /Mole-Sec                                                     210
                                       xv

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                                   SECTION  1

                                 INTRODUCTION


     To support the methodology  presented  in  Volume 1 monitoring  information
and data  on  the behavior and  fate of  hazardous constituents in soil  systems
are presented here in Volume 2 of  the Manual.   This  additional  information  is
intended  to  provide  the  manual  user  with more  information  and  background
material  for making  more  complex decisions   and analyses  concerning  site,
soil,  and waste interactions than can  be  presented in Volume  1.

     Section 2,  "Monitoring,"  includes   a  discussion  of  the factors  required
for a   comprehensive  and  effective monitoring  program  including  soil  care,
soil pore  liquid,  unsaturated  zone, groundwater  and  atmosphere  sampling.   A
monitoring program is necessary to  assure  that  the objectives of  the  in-place
treatment program are being  met.

     Section  3,  "Characterization  and   Evaluation  of  Fundamental Processes
in  Soil/Waste  Systems,"  presents   information  on the  behavior  and  fate  of
hazardous  constituents  in  soil  systems.   The  information  presented  served
as a basis  for  selecting  treatment techniques and developing the  methodology
for in-place  treatment.   Elements  of  soil/waste systems considered  included
site and  soil  factors  important  in influencing in-place treatment,  soil
mobilization processes for leaching and volatilization  control,  biodegradation
processes  and  transformation  processes.   A  brief  discussion  addressing the
modeling of waste constituents  in soil systems is presented.

     The  Appendix  provides   compound  properties  and adsorption,  degradation
and volatilization  parameters   for various chemical  compounds.   A  glossary
of terms is also included.

     The  information  in  Volume 2 represents  an effort to present the  manual
user with the most  current  information  and research activities that  directly
or  indirectly  influence  the  in-place   processes and  treatment  techniques.
The topics addressed present areas  of  critical concern  and provide  fundamental
principles  for  characterizing  the  basic   processes   in  soil/waste  systems.
Since most in-place treatment techniques have not been thoroughly  tested, the
information in Volume 2 will provide the background  or framework  for  planning
and  interpreting   in-place   treatment  techniques  specifically  addressed  in
Volume  1.

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                                   SECTION  2

                                  MONITORING
INTRODUCTION

     During the  execution  of  an  in  situ  remedial  action,  the  primary  ob-
jectives  are  to  prevent  off-site  migration  of  hazardous  constituents  via
migration to ground or surface waters or transmission through the  atmosphere,
as well as to render the wastes nonhazardous through degradation,  detoxifica-
tion,  or  immobilization.   To  assure  that these objectives  are  being met,  a
monitoring program must be established.

     Specific  objectives  of a  monitoring  program  are  to:   (K.  W. Brown  and
Associates 1980,  U.  S.  Environmental  Protection Agency 1983):

     1.   Assure that  the  hazardous or  toxic  constituents   of  the waste  are
being degraded,  detoxicated, or inactivated  as  planned.

     2.  Monitor degradation rates of  degradable constituents.

     3.   Assure  that waste  constituents  are  not entering runoff  or  leachate
water  and leaving the area in unacceptable  concentrations.

     4.   Determine  whether adjustments  in treatment  management  are  needed
to maintain the  treatment process (e.g.,  Is  soil  pH within  desirable  range?
Are  adequate  nutrients available for  biological  degradation of organic  con-
stituents?  Does  soil  moisture require  adjustment?   Are additional  chemical
amendments needed to complete chemical  treatment of the  wastes?).

     A  complete  monitoring program would  include  the  media listed   in  Table
2-1.   The waste constituents to  be monitored  in the various media  are  those
determined to  be hazardous in the initial  site/waste characterization study as
well as expected important degradation or transformation products.  Nonhazard-
ous  constituents  and/or  their  transformation/degradation  products   and  soil
properties which  might affect treatment  processes should also be monitored.
The  monitoring  program may  include substances  which  are required for  treat-
ment,  whether  native to the soil  or added as a  treatment agent.

STATISTICAL CONSIDERATIONS

     A  limitation in field sampling is the large number  of samples  required to
ensure  that  tne measured  mean value  of  a particular  parameter  is   within  a
given  range  of  a  true value  (Wilson  1980).    This  limitation  is  due  to  the
natural spatial  variability  of soil properties.   It  is  therefore  necessary to

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           TABLE 2-1.   REQUIREMENTS  OF  A  COMPLETE MONITORING PROGRAM
           (ADAPTED FROM U.S.  ENVIRONMENTAL  PROTECTION AGENCY 1983)
   Media to be Monitored                         Purpose


Soil in the treatment zone           Determine extent of degradation, trans-
                                     formation,  and  immobilization pH and
                                     nutrient status, and any other factors or
                                     substances  affecting  treatment execution
                                     and  effectiveness.

Soil cores (unsaturated zone)         Determine slow  movement of hazardous
                                     constituents.

Soil-pore liquid in the              Determine highly mobile constituents.
unsaturated zone

Groundwater                          Determine mobile constituents.

Runoff water                          Determine -migration off-site of soluble,
                                     suspended,  or adsorbed constituents.

Air                                  Determine personnel and population
                                     health  hazards.
take a significant number of replicate  samples which are representative of the
area  being  sampled.   Realistic,  unbiased  data are  required  so  that  valid
comparisons can be  made  between  the  values  of monitored parameters and back-
ground values.

     The hazardous waste site should be divided into uniform areas for sampl-
ing purposes.   These areas may be  according to soil series or to phases based
on surface texture within a series.  If known "hot spots" of wastes or signi-
ficant differences  in  types of wastes occur  at the  site,  these areas should
also be monitored  separately.   For  each medium sampled, appropriate background
sampling sites  should be  monitored.

     Guidelines  for  statistical  sampling procedures within the selected
areas  are given  in  Hazardous Waste  Land Treatment (U.  S.  Environmental
Protection  Agency  1983)   arid  Test  Methods for Evaluating Solid Waste  (U.S.
Environmental  Protection  Agency  1982c).Professionals who  may  be consulted
for assistance may  include  certified professional  soil  scientists, statisti-
cians, and environmental  analytical chemists.

SOILS SAMPLING  IN  THE TREATMENT ZONE  AND IN
THE UNDERLYING  UNSATURATED ZONE

     Soil  cores  and  borings  are  used  to measure  the  vertical movement  of
waste  constituents  as well as  to determine  the  progression of treatment

-------
in the  soil  treatment  zone.    Soil  core  sampling  in the  treatment  zone  is
used  as  a  management  tool.  The  extent  of  treatment  (i.e., degradation,
transformation,   and/or  immobilization)  of  the  hazardous  constituents   can
be monitored as well as  factors  which  may affect the execution of the  treat-
ment, such as nutrients  and  pH.   Soil  core sampling below the treatment  zone
is used to determine whether significant  concentrations of  hazardous constitu-
ents  are moving  below  the treatment zone.   If unacceptable leaching of  con-
taminants  is  occurring,   contingency  plans should  provide  means  to prevent
groundwater contamination,  such  as  the  use  of  a grout  bottom  seal.

     Soil sampling  methods  used  by  soil  scientists and  irrigation  and drainage
engineers  to  evaluate  physical  properties of soils  are  also  suitable   for
determining chemical constituents in the upper  layers of soils (Wilson  1980).
Several  types of equipment which have been used are  listed  in Table 2-2.   The
split spoon  sampler  is a barrel-type auger, with one  side which  pivots  on  a
hinge.  A  tube-type  sampler  consists  of a tube bevelled and sharpened  on one
end to aid insertion in the soil.   A drive  hammer  is  used to  force the tube to
the desired depth,  and  an intact  soil core  is  removed  from  the tube.

     Wilson  (1980)  identified several  problems  associated  with  the  use  of
soil   samplers.   With  augers  and tube-type samplers,  dry soil may  fall   out
of the  unit  when  it  is  withdrawn  from  the soil, which requires  the  use  of
a  core  catcher.    Also,   if  a soil  is  wet,  chemical  interactions  occurring
between  the  soil  water  and  metal  parts  of  the  sampler  may introduce metal
contamination  into  the  sample.    Contamination  is  an  especially   important
problem  in the  case  of  organic  chemicals  and microorganisms.   Techniques
for microbial sampling  have  been described by Bordner,  Winter,  and Scarpino
(1978) and for organic  and microbial  sampling  by Dunlap et  al.  (1977).   One of
the most promising  methods  appears to be  the  use of a combination  auger/dry
tube  corer technique.   A hole is augered  to  the  top of  the desired sampling
depth; then the soil is  sampled  with  a core sampler forced  into the sampling
region.   Wilson  (1980)  suggests  that  a lucite  plastic insert in the dry  tube
coring barrel would minimize contamination  with metals.
          TABLE 2-2.   EQUIPMENT FOR FIELD COLLECTION  OF  SOIL  SAMPLES
                                (WILSON  1980)
Hand-driven Equipment                    Power-driven  Equipment
Screw-type auger                      Continuous flight  power auger
Post-hole auger                         (hollow-stemmed)
Barrel auger                          Core sampler
Dutch auger                           Bucket auger
Split-spoon sampler                   Cable-tool drill rig
Tube-type sampler                     Rotary drill  rig
Auger/dry-tube corer

-------
     Soil samples from  lower  soil  depths are more easily obtained  by  the  use
of  powered  coring  or drilling equipment.   The U.S. Environmental  Protection
Agency  (1983)  suggest^,  that  even for  samples at  shallower depths,  powered
equipment may  be less    ctly  due to  clean,  minimally disturbed samples  for
analysis.

      Several types  of  p   .--driven  sampling  units  are  listed  in  Table  2-2.
Coring type machines are generally more desirable  than  drilling  rigs since  the
addition  of  water  during  the  drilling operation, to  remove cuttings and  in
some cases mud to hold  open the  hole,  may  change  the soil water chemistry  and
may result  in  sample contamination.   Air rotary drilling rigs,  which  use  air
to  bring  cuttings  to the  surface, do  not  have the  problem  of  contamination.
Spiral type  augers,  unless hollow-stemmed  (which  allows  for the insert of  a
core sampler), are  not  recommended because  of difficulty in determining  the
depth the sample was taken (Wilson 1980).

     After  soil  core sampling,  holes  should be backfilled  with native  soil
(compacted to field bulk density),  clay slurry, or  other  suitable materials  in
order  to  prevent the  channelling of  hazardous constituents  down  the holes
U.S. Environmental  Protection  Agency  1983).

     Procedures for handling,  preserving,  and shipping  soil  solids samples  may
be  found in Test Methods for  Evaluating  Solid Waste  (U.S.  Environmental
Protection Agency 1982c).

SOIL PORE LIQUID  SAMPLING IN
THE UNSATURATED ZONE

     Water added to  a site by  precipitation  or irrigation   while percolating
through the  treatment  zone may  rapidly  transport  some mobile  hazardous con-
stituents  or transformation  products   through  the  unsaturated  zone  to  the
groundwater  (U.S.  Environmental  Protection  Agency  1983).    The purpose  of
soil-pore liquid monitoring is  to  detect these rapid  pulses of contaminants.
Heavy  precipitation,  snow melt, and irrigation  events are   often responsible
for such  pulses,  and sampling  periods should  be  scheduled  to correspond  to
such events.   Soil  texture and  structure  and other  soil properties,  as  they
affect  infiltration  and  percolation   rates,  also  determine to  what extent
precipitation events cause rapid  water  movement in a  particular  soil  and  can
be used as predictive tools to  schedule sampling events.

     Soil pore  liquid  sampling  may  also   indicate  the   amount  of   materials
leaching  to  the groundwater.    Samples of  groundwater  do   not  provide this
information  due  to  the diluting  effect  of  the  groundwater.    In  addition,
analysis  of  the  soil pore liquid can  provide an early  warning signal  that
remedial   action  is  required  for  the  management  of  the  treatment process.

     Since water  in  the  unsaturated  zone   is  held  under  negative pressure
(suction), wells  and open cavities cannot be used  to  collect  the  flowing
water.   Therefore samplers in  the unsaturated zone  are  called suction sampling
devices.    A summary  of various types  of  suction samplers  are  presented  in
Table  2-3.   The reader is referred  to Wilson (1980)  for a  comprehensive
discussion of these  samplers.

-------
          TABLE  2-3.  SOIL-PORE  LIQUID SAMPLING DEVICES (WILSON 1980;
     Sampl ing  devices
     A.   Ceramic-type  samplers

         1.   Suction cup

             a.   Vacuum-operated  soil-water samplers
             b.   Vacuum-pressure  samplers
             c.   Vacuum-pressure  samplers with check valves

         2.   Filter candle

     B.   Cellulose-acetate  hollow fiber samplers

     C.   Membrane filter  samplers
WATER SAMPLES  FROM  THE  SATURATED  ZONE
(i.e., groundwater)

     Groundwater  sampling  will  indicate  whether  hazardous  waste  constitu-
ents have indeed migrated to  the groundwater  and may present a public health
hazard,  depending  on  the  hydrogeological  characteristics  and  uses  of  the
groundwater  system.   If contamination  has  occurred  and  is deemed unacceptable,
provisions must be  made to recover and treat or  otherwise  handle the contami-
nated groundwater.

     Sophisticated   groundwater  sampling  equipment  and  procedures  are  not
desirable for monitoring  programs  (U.  S. Army Corps  of Engineers  1982).
Rather, to ensure long-term,  efficient operation  of the monitoring system, the
devices should be simple, rugged, foolproof, and operable  by  trained,  but not
necessarily  educationally  skilled  personnel   (Vanhoff,  Weyer,  and Whitaker
1979).   In  Table 2-4,  a list of saturated zone  sampling  methods   and sample
extraction techniques  are  given.   Again,  the reader is  referred  to Wilson
(1980) for  a  discussion of these methods.   In  addition,  the U.  S. Environ-
mental  Protection  Agency  (1983) has  suggested  the following  documents  as
sources of information on groundwater  monitoring:

     1.  Manual of  Ground-Water Sample Procedures (Scalf  et al.  1981):

     2.   Ground-Water  Manual  (U.S.   Department  of  the  Interior,  Bureau  of
Reclamation  1977);

     3.  Procedures Manual  for Ground-Water  Monitoring  at Solid  Waste  Disposal
Facilities (U.S.  Environmental Protection  Agency 1977);

-------
CUSTOMER  MEMO
     Dear Colleague,

       In this issue, Digest focuses its attention on scientific and technical information from
     abroad.
       NTIS has just concluded an agreement with the Japan Information Center of Science
     and Technology (JICST) to make  available, in English, a catalog listing some  16,000
     science  and technology research projects  currently ongoing in Japan. The sponsoring
     institutions  and researchers'  names  are  provided to  give interested  individuals  an
     opportunity to communicate directly with their Japanese counterparts. In addition, NTIS
     has just negotiated to distribute a quarterly JICST bulletin which summarizes (abstracts)
     the results of Japanese electronics research.  The ad on page 10 lists reports from JICST on
     renewable energy resources.
       Featured  inside  are foreign  technology  reports   acquired  by  NTIS'  Office  of
     International Affairs. These items, arranged by subject category, illustrate the wide range
     of research available as the result of an extensive foreign acquisition program.
       For more information on the above products and reports, please write to Mr. David
     Shonyo, Director, Office of International Affairs, Springfield, VA 22161.
       The HOTLINE section, on page 15, features reports from the International Food Policy
     Research Institute (IFPRI).
       Trade Press reports, including one published by the International Trade Administration,
     are described on page 9.
       An ad on The Role of Metrics in U.S. Exports appears on page 11.
       Other sections and  ads in Digest cover various products and reports. For example,
     Database News, on page 17, announces the availability of new data files from the Energy
     Information Administration (El A)  as well  as updates to others previously highlighted.
     Also, new data files  from  the National Center for Health Statistics (NCHS) and  the
     Defense Logistics Supply Center (DLSC) are listed. Six new titles of data files available
     on floppy diskettes are also cited.
       If you have any questions or recommendations about Digest, please let me know.
                                                   Sincerely,
                                                   Lois Grooms
                                                   Editor


-------
The following listing of current and recent research from
worldwide sources reflects the growing stream of foreign
technology flowing to NTIS. These reports are the positive
results produced by an aggressive NTIS Foreign Technol-
ogy Acquisition Program administered by the NTIS Office
of International Affairs. This program is designed to be
responsive to the information needs of U.S.  industry by
acquiring targeted foreign  technology.  Telephone David
Shonyo, (703) 487-4822, if you have any questions.

Aeronautics

Deregulation  of  Air  Transport: A Perspective  on the
Experience in the United States.
Civil Aviation Authority, London (England). 1984. 69pp.
PB84-230630/CAO  PC$11.50/MF$11.50

Methodology of Runway  Capacity Assessment   A
Summary Paper.
Civil Aviation Authority, London (England). 1983. 23pp.
PB84-204403/CAO  PC$9.50/MF$9.50

Evaluation of a Mobile Aerodynamic Test Facility for Hang
Glider Wings.
Cranfield Inst.  of Tech. (England). Nov. '83, 125pp.
PB84-170315/CAO  PC$15.50/MF$15.50

Biological & Medical Sciences

Health and Safety in the Plastics and Rubber Industries 2,
Conference Held at University of York on April 16-17,
1984.
Plastics and Rubber Inst., London (England). 1984. 179pp.
PB84-232768/CAO  PC$21.50/MF$21.50

Technological Forecasting for Downstream Processing in
Biotechnology. Phase I. Intermediate Forecast Report.
Commission of the European Communities, Luxembourg.
1982. 87pp.
PB83-200576/CAO  PC$13.50/MF$13.50

Technological  Forecasting for Downstream Processing in
Biotechnology.  Phase  II.  Process  and Unit  Operation
Needs. FAST Series No. 7.
Commission of the European Communities, Luxembourg.
1983. 121pp.
PB84-214980/CAO  PC$15.50/MF$15.50

Safety Aspects of Storage, Handling and Use of Chlorine
and Sulphur Dioxide.
National Joint Health and Safety Committee for the Water
Service, London  (England). Apr. '82,  54pp.
PB84-167907/C AO  PC$ 11.50/MF$ 11.50

Guidelines for Recording Industrial  Hygiene Data.
CONCAWE, The Hague (Netherlands).  1983. 27pp.
PB84-128842/CAO  PC$11.50/MF$11.50

International Symposium on Protection  Against Chemical
Warfare Agents Held at Stockholm, Sweden on June 6-9,
 1983.
 Foersvarets Forskningsanstalt, Umea (Sweden). Aug. '83,
 123pp.
 PB84-109586/CAO  PC$15.50/MF$6.50

 Science and Technology for Aquaculture Development
 National  Board  for  Science  and Technology, Dublin
 (Ireland). 1982.  177pp.
 PB84-109222/CAO  PC$23.50/MF$23.50
Civil Engineering

Aerobic Thermophilic Digestion of Sludge Using Air 
Full Scale Operation.
Electricity Council Research Centre, Capenhurst (England).
Mar. '84, 33pp.
PB84-202019/CAO  PC$11.50/MF$11.50

Sludge Treatment Plant for Waterworks.
Water Research Centre, Stevenage (England). 1983. 83pp.
PB84-201771/CAO  PC$19.50/MF$19.50

How to Design Sewage Sludge Pumping Systems.
Water Research Centre, Stevenage (England). 1983. 90pp.
PB84-201755/CAO  PC$19.50/MF$19.50

Polyelectrolyte Users' Manual.
Water Research Centre, Stevenage (England). 1983. 58pp.
PB84-201748/CAO  PC$17.50/MF$17.50

Quantification of Sewage Odours.
Queensland Univ., Brisbane (Australia).  Jan. '83, 45pp.
PB84-116169/CAO  PC$11.50/MFS6.50
Communications Technology

Implementation Strategies for  Digital  Signal  Processing
Systems.
Helsinki Univ. of Technology, Espoo (Finland). Mar.  '84,
90pp.
PB84-214303/CAO   PC$13.50/MF$6.50

Formalism for the Design and Evaluation of Parallel Signal
Processing Systems.
Helsinki Univ. of Technology,  Espoo (Finland). Apr.  '84,
 165pp.
PB84-214253/CAO   PC$19.50/MF$6.50

 DFSP: A Data Flow Signal Processor.
 Helsinki Univ. of Technology, Espoo (Finland). Jun.  '83,
 51pp.
 PB84-112135/CAO   PC$11.50/MF$6.50

 Network Reliability  A Brief Introduction.
 Norges  Tekniske Hoegskole,  Trondheim (Norway). Jan
 '83, 25pp.
 PB84-109792/C AO   PC$9.50/MF$9.50
 Computers
 Proteus Distributed Database System.
 Kent Univ., Canterbury (England). 1984.  23pp.
 PB84-234350/CAO  PC$9.50/MF$9.50

 Real-Time Languages for Process Control.
 Warren Spring Lab., Stevenage (England). 1984. 90pp.
 PB84-234319/CAO  PC$15.50/MF$15.50

 Uniform User  Interface  for  Modular Pascal Operating
 Systems.
 Groningen  Rijksuniversiteit  (Netherlands).  Apr.  '84,
  124pp.
 PB84-215896/CAO  PC$15.50/MF$6.50

 Large-Dictionary, On-Line Recognition of Spoken Words.
 Helsinki Univ. of Technology, Espoo (Finland).  1983.
 68pp.
 PB84-214246/CAO   PC$11.50/MF$6.50

 LispKit Manual. Volume 1.
 Oxford Univ. (England).  1983. 129pp.
  PB84-204874/CAO   PC$17.50/MF$17.50

-------
LispKit Manual. Volume 2. (Sources).
Oxford Univ. (England). 1983. 140pp.
PB 84-204882/C AO  PCS 17.50/MF$ 17.50

Interfacing UNIX to Data Communications Networks.
Newcastle upon Tyne Univ. (England). 1983. 41pp.
PB84-205996/CAO  PC$11.50/MF$11.50

Practical Fault  Tolerant Software for Asynchronous Sys-
tems.
Newcastle upon Tyne Univ. (England). 1983. 10pp.
PB84-205970/CAO  PC$9.50/MF$9.50

IBM to Cambridge Ring Interface.
Science  and   Engineering  Research  Council,   Chilton
(England). 1984. 49pp.
PB84-205228/CAO  PC$11.50/MF$11.50

Notes on Communicating Sequential Processes.
Oxford Univ. (England). 1983. 157pp.
PB 84-204817/C AO  PC$ 19.50/MF$ 19.50

Converting to ADA Packages.
National Physical Lab., Teddington (England). 1984. 23pp.
PB84-203892/CAO  PC$9.50/MF$9.50
Guidelines for the Design of Large Modular Scientific
Libraries in Ada.
National  Physical  Lab.,  Teddington  (England).  1984.
154pp.
PB84-203808/CAO  PC$19.50/MF$19.50

Abstract Machine Support for Purely Functional Operating
Systems.
Oxford Univ. (England). 1983. 46pp.
PB84-202316/CAO  PC$11.50/MF$11.50

Colour Order Systems for Computer Graphics. I. Trans-
formation of NCS Data into CIELAB Colour Space.
Foersvarets Forskningsanstalt, Stockholm (Sweden). Jan.
'84, 93pp.
PB84-179688/CAO  PC$13.50/MF$6.50

Personal  Computers  in Japan:  The  Most Up-to-Date
Information on Japanese Computer Industries.
PB  Co. Ltd., Tokyo (Japan). Dec. '83, 127pp.
PB84-176510/CAO  PC$25/MF$25

Annotated Bibliography of Recent Publications on Data
Security and Cryptography (6th).
National Physical Lab., Teddington (England). 1983. 33pp.
PB84-169168/CAO  PC$11.50/MF$11.50

Newcastle Connection or UNIXes of the World Unite.
Newcastle upon Tyne Univ.  (England). 1982. 24pp.
PB84-160571/CAO  PC$9.50/MF$9.50

Programs for Handling RC-Coded Images.
Foersvarets Forskningsanstalt, Stockholm (Sweden). Dec.
'83, 47pp.
PB84-158260/CAO  PC$11.50/MF$6.50

Computer Communications Projects.
Leeds Univ. (England). Dec. '81, 27pp.
PB84-145200/CAO  PC$11.50/MF$11.50

Networking Standards: A Comparison.
Leeds Univ. (England). 1983. 35pp.
PB84-144385/CAO  PC$11.50/MF$11.50
Distributed Secure System.
Newcastle upon Tyne Univ. (England). 1982. 50pp.
PB84-141126/CAO  PCS 11.50/MF$11.50

Unknotting Fortran.
Kent Univ., Canterbury (England). Oct. '83, 14pp.
PB84-139047/CAO  PC$9.50/MF$9.50

Verification of Secure Systems.
Newcastle upon Tyne Univ. (England). 1982. 76pp.
PB84-138718/CAO  PC$13.50/MF$13.50

Construction Engineering & Materials

Comparative Evaluation of Insulating Sealed Glass Units.
Ontario  Ministry  of Municipal Affairs  and  Housing,
Toronto (Canada). Jan. '84, 79pp.
PB84-210582/CAO  PC$13.50/MF$6.50

CIRIA (Construction Industry Research and Information
Association)  Guide to Concrete Construction in the Gulf
Region.
Construction Industry Research  and Information Associa-
tion, London (England). 1984. 108pp.
PB84-203504/CAO  PC$112.50/MF$112.50

Site Investigation Manual.
Construction Industry Research  and Information Associa-
tion, London (England). 1983. 148pp.
PB84-203488/CAO  PC$27/MF$27

Use of Waste Materials from Coal Combustion in Road
Construction.
Statens Vaeg- och Trafikinstitut, Linkoeping (Sweden).
1984. 311pp.
PB84-172006/CAO  PC$34.50/MF$34.50

Development and Use of Composite Fibrous Materials and
Structures: A Construction Survey.
Sydney Univ. (Australia). Feb.  '83, 32pp.
PB84-170513/CAO  PC$11.50/MF$6.50

High Performance Roofing Systems (Conference, 1 March
1984).
Plastics and  Rubber Inst., London (England). Mar. '84,
98pp.
PB84-178243/CAO  PC$13.50/MF$13.50

Preliminary Investigation of Test Methods for the Assess-
ment of Strength  of in Situ Concrete.
Cement  and  Concrete  Association,  Slough  (England).
1982. 40pp.
PB84-162031/CAO  PC$11.50/MF$11.50

Fire and Plastics in Buildings.
National Building Research Inst., Pretoria (South Africa).
1982. 18pp.
PB84-126648/CAO  PC$9.50/MF$6.50

Make Your Home a Quiet Refuge.
National Building Research Inst., Pretoria (South Africa).
1982. 14pp.
PB84-126291/CAO  PC$9.50/MF$6.50

Waffle Shells for Roof and Floor.
Structural Engineering Research Centre, Madras  (India).
Oct. '81, 65pp.
PB84-125814/CAO  PC$13.50/MF$13.50

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Earth Sciences
RTRSOC  (Real  Time  Reporting  System  on  Oceanic
Conditions) Concept of Space Station Missions.
RTRSOC Concept Study  Group,  Tokyo  (Japan).  1984.
304pp.
PB84-238807/CAO   PC$25/MF$25

Applications of Remote Sensing Techniques to Oceanog-
raphy and Sea Ice.
Foersvarets Forskningsanstalt, Stockholm (Sweden). Apr.
'84,  16pp.
PB84-231208/CAO   PC$9.50/MF$6.50

Algorithm to Compute the Geoid Surface.
Institute of Oceanographic  Sciences,  Birkenhead  (Eng-
land). 1983. 22pp.
PB84-204288/CAO   PC$9.50/MF$9.50

Contour-To-Grid Transformation:  Development  of  a
Method for Generation of a  Sparse Grid Structure Out of
Terrain Elevation Contours.
Foersvarets Forskningsanstalt, Stockholm (Sweden). Dec.
'83,  35pp.
PB84-158237/CAO   PC$11.50/MF$6.50

Rock Dynamics.
Stiftelsen Svensk Detonikforskning, Stockholm (Sweden).
1983. 21pp.
PB84-127042/CAO   PC$9.50/MF$6.50
Electronics

Modelling the MOSFET Using ASTAP (Advanced Statis-
tical Analysis Program).
Science  and  Engineering  Research  Council,   Chilton
(England). 1984. 51pp.
PB84-204478/C AO  PC$ 11.50/MF$ 11.50

Digital Filters and Reverberation Time Measurement.
Bradford Univ. (England). Jul. '83, 83pp.
PB84-163104/CAO  PC$13.50/MF$13.50

Computer-Aided  Design  of Microstrip  Hybrid Signal
Dividers.
Bradford Univ. (England). Jul. '83, 31pp.
PB84-163096/CAO  PC$11.50/MF$11.50

Characterization  of  Microstrip  Fixtures,  a Broad Band
Model for a Microstrip Connector.
Foersvarets Forskningsanstalt, Stockholm (Sweden). Sep.
'83, 47pp.
PB84-130095/CAO  PC$11.50/MF$6.50

Impedance  Loaded  Circular Wire Loop as Receiving
Antenna.
Technische  Nogeschool, Delft  (Netherlands). Aug.  '83,
82pp.
PB84-115500/CAO  PC$13.50/MF$6.50
 Energy & Fuels

 Catalytic Coal Gasification.
 International  Energy  Agency  Coal  Research,  London
 (England).  1984. 60pp.
 PB84-233238/CAO  PC$18/MF$18
International Meeting on Lithium Batteries (2nd) Held at
Paris on April 25-27, 1984.
Centre de Documentation de I'Armement, Paris (France).
Apr. '84, 125pp.
PB 84-222702/C AO  PC$ 1 5 . 50/MFS 15.50

Consequences of  Limiting Benzene  Content of Motor
Gasoline.
CONCAWE, The Hague (Netherlands).  1983. 19pp.
PB84-170240/CAO  PC$9.50/MF$6.50

Symposium on Nuclear Heat for High Temperature Fossil
Fuel Processing Held at London, England on 28 April 1981 .
Institute of Energy, London (England). 1981. 82pp.
PB84-167261/CAO  PC$19.50/MF$19.50

Survey  of  the  Technological Requirements  for High-
Temperature Materials R and D (Research and Develop-
ment). Section 1: Diesel Engines.
Commission of the European Communities, Luxembourg.
1983. 72pp.
PB84- 164524/CAO  PC$1 1 .50/MF$1 1 .50

Symposium on Nuclear Heat for High Temperature Fossil
Fuel Processing Held at London, England on 28 April 1981 .
Institute of Energy, London (England). 1981. 82pp.
PB 84- 1 6726 1 /CAO  PC$ 1 9 . 50/MF$ 1 9 . 50

Hydrogen Safety Manual.
Commission of the European Communities, Luxembourg.
1983. 520pp.
PB84- 1 63468/CAO  PC$43 . 50/MFS43 . 50

Precautionary Advice on the Handling of Motor Gasolines.
CONCAWE, The Hague (Netherlands).  1983. 19pp.
PB84- 15897 1/CAO  PC$9.50/MF$6.50
Combustion of Coal Liquid Mixtures.
International Energy  Agency  Coal
(England). 1983. 54pp.
PB84-138981/CAO   PC$18/MF$18
                                  Research,  London
Characteristics of Petroleum and Its Behaviour at Sea.
CONCAWE, The Hague (Netherlands).  1983. 56pp.
PB84-132711/CAO  PCS11.50/MFS6.50

Waste Utilisation Technologies.
National  Board  for  Science  and  Technology,  Dublin
(Ireland). 1981.  35pp.
PB 84- 1 08976/C AO  PCS 1 1 . 50/MF$ 1 1 . 50
Environment

Influence of Wind on the Dust Emission from a Municipal
Refuse Incinerator.
Sheffield Univ. (England). Nov. '82, 18pp.
PB84-233592/CAO  PC$9.50/MF$9.50

Wind Tunnel Modelling of Buoyant Plumes.
Oxford Univ.  (England). Jan. '84, 252pp.
PB84-203413/C AO  PC$28.50/MF$28.50

Field Guide to Inland Oil Spill Clean-Up Techniques.
CONCAWE, The Hague (Netherlands). 1983. 104pp.
PB84-174085/CAO  PC$15.50/MF$6.50

Acid Rain and Forest Decline in West Germany.
Forestry Commission, Edenburgh (Scotland).  1983. 17pp.
PB84-162239/CAO  PC$9.50/MF$9.50

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Industrial Engineering & Manufacturing Technologies

Gas Metal Arc-Narrow Gap Welding.
Valtion Teknillinen Tutkimuskeskus,  Espoo  (Finland).
1984. 30pp.
PB84-214212/CAO  PC$11.50/MF$6.50

Computer Aided Fault Tree Synthesis.
Commission of the European Communities, Luxembourg.
1983. 52pp.
PB84-211689/CAO  PC$11.50/MF$11.50

Bridging  the  CAD-CAM   (Computer Aided Design-
Computer Aided Manufacture) Gap for Casting  Design 
An Opportunity for the Development of Expert Systems.
University  of  Wales Inst.  of Science and Technology,
Cardiff. 1984.  6pp.
PB84-168178/CAO  PC$9.50/MF$9.50

Flexible Manufacturing  Systems  Some  Guidelines for
the Non-Specialist.
University  of  Wales Inst.  of Science and Technology,
Cardiff. 1984.  8pp.
PB84-167451/CAO  PC$9.50/MF$9.50

Study on Evaluation of Print Quality.
Mitsubishi  Heavy Industries Ltd., Tokyo  (Japan).  Nov.
'83, 13pp.
PB84-132026/CAO  PC$9.50/MF$6.50

Mini-Seminar on Quality Assurance.
Council for Scientific and  Industrial Research, Pretoria
(South Africa). Nov. '82, 66pp.
PB84-125640/CAO  PC$11.50/MF$6.50

Analysing  Products with Respect to  Flexible  Assembly
Automation.
Norges Tekniske  Hoegskole, Trondheim (Norway).  May
'83, llpp.
PB84-109966/CAO  PC$9.50/MF$9.50

Role of the Chip-Tool Interface in Machining.
Cambridge Univ.  (England).  1982. 13pp.
PB84-107267/CAO  PC$9.50/MF$9.50	

Important: Please order all  reports bv complete Order
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Marine Engineering

Study  on  Motions of High Speed Planing Boats  with
Controllable Flaps in Regular Waves.
Technische  Hogeschool.  Delft (Netherlands).  Apr.  '84,
66pp.
PB84-216761/CAO  PC$11.50/MF$6.50

Calculation of Sailing Yacht  Resistance.
Technische  Hogeschool,  Delft (Netherlands). Dec.  '83,
60pp.
PB84-184266/CAO  PC$11.50/MF$6.50

Estimating the  Flexibility of Offshore Pile Groups.
Sydney Univ. (Australia). Jan. '83, 28pp.
PB84-116938/CAO  PC$11.50/MF$6.50
Development of Hull Forms for RO-RO (Roll-on/Roll-off)
Ships and Ferries.
Statens  Skeppsprovningsanstalt,  Goeteborg  (Sweden).
1983. 34pp.
PB84-107572/CAO  PC$11.50/MF$6.50

Materials (Metallic)

Creep Damage Mechanics and Micro mechanisms.
National Physical Lab., Teddington (England). 1984. 32pp.
PB84-236314/CAO  PC$11.50/MF$11.50

Special Steels  and Systems  for Corrosion Prevention in
Reinforced Concrete.
Concrete Society, London (England).  1983. 118pp.
PB84-233915/C AO  PC$ 15.50/MF$ 15.50

Fatigue Crack Growth and Fracture Resistance of Steels in
High-Pressure Hydrogen Environments.
Commission of the European  Communities, Luxembourg.
1983. 67pp.
PB84-213230/CAO  PC$11.50/MF$ 11.50

Development of a  Ni-Base Heat Resistant Alloy (TOMIL-
LOY) for Gas Turbine Combustor.
Mitsubishi Heavy  Industries Ltd., Tokyo (Japan). 1984.
13pp.
PB84-170265/CAO  PC$9.50/MF$6.50

Swedish Symposium on Non-Metallic Inclusions in Steel
Held on 27-29 April,  1981.
Swedish Inst.  for Metals Research,  Stockholm.  1981.
467pp.
PB83-131292/CAO  PC$34/MF$4.5()

Materials (Non-Metallic)

Fibre Reinforced Composites  '84  International Confer-
ence Held at  the  University  of Liverpool  on April  3-5,
1984.
Plastics and Rubber Inst., London (England). Apr.  '84,
414pp.
PB84-236355/C AO  PC$40.50/MFS40.50

Non-Linear Data Fitting for the Analysis of Creep Rupture
Data on GRP Materials in Aggressive Environments.
National Physical Lab., Teddington (England). 1984. 24pp.
PB84-236280/CAO  PC$9.50/MF$9.50

Research on the Applications of and Material Resources for
Fine Ceramics.
Research Inst.  for  Natural Resources, Tokyo (Japan). Jul.
'84, 125pp.
PB84-220045/CAO  PC$17.50/MF$6.50

Survey of  the Technological  Requirements  for  High
Temperature Materials R  and  D. Section 2: Composites.
Commission of the European  Communities, Luxembourg.
1982. 31pp.
PB84-215136/CAO  PC$9.50/MF$9.50

Polymers in Cables. Conference Held at Mere Golf and
Conference Centre, Knutsford,  Cheshire on May  18-19,
1983.
Plastics and Rubber Inst.,  London (England).  1983. 245pp.
PB84-203793/CAO  PC$25.50/MF$25.50

Fatigue Damage: Mechanics  of Carbon-Fibre  Reinforced
Laminates.

-------
Cambridge Univ. (England). Dec.  '83, 66pp.
PB84-170133/CAO  PC$13.50/MF$13.50

GC-MS Studies on the Pyrolysis of Wood and Lignin.
Helsinki Univ. (Finland). 1982.  10pp.
PB84-157726/CAO  PC$9.50/MF$6.50

Fatigue in Polymers: International  Conference Held at the
Forum Hotel, London on 29-30 June, 1983.
Plastics and Rubber Inst., London (England). 1983. 175pp.
PB84-142199/CAO  PC$19.50/MF$19.50

Polypropylene Fibres and Textiles:  International Confer-
ence (3rd) Held  at University of York on 4-6 October,
1983.
Plastics and Rubber Inst., London (England). 1983. 424pp.
PB84-142207/CAO  PC$37.50/MFS37.50

Polyethylenes 1933-83: Golden Jubilee Conference Held at
Royal Lancaster Hotel, London on 8-10 June, 1983.
Plastics and Rubber Inst., London (England). 1983. 443pp.
PB 84- 142223/C AO  PC$37.50/MFS37.50

Energy Conservation  the Use of Foamed and Expanded
Plastics: Conference Held on 6 December 1983.
Plastics and Rubber Inst., London (England). 1983. 71pp.
PB84-142215/CAO  PC$11.50/MF$11.50

Carbon Fibre Reinforced Polysulphone  for Orthopaedic
Surgical Implants: Proposed Paper for International Confer-
ence on Biomedical Polymers Held at Durham 12-14, July
1982.
National Mechanical Engineering Research Inst., Pretoria
(South Africa). 1983. 17pp.
PB84-124304/CAO  PC$9.50/MF$6.50

Resin Development in Advanced Composites.
Foersvarets  Forskningsanstalt, Stockholm (Sweden). Sep.
'83, 62pp.
PB84-113539/CAO  PC$11.50/MF$6.50

Repair of Ballistically Impacted Carbon Fibre  Reinforced
(CFR) Laminates.
Cranfield Inst. of Tech.  (England). Nov. '82, 23pp.
PB84-108612/CAO  PC$9.50/MF$9.50

Failure Criteria for Timber Subjected to Complex Stress
States Due to Short Term Loading.
Timber  Research and  Development  Association, High
Wycombe (England). Jan. '82, 30pp.
PB84-107721/CAO  PC$11.50/MFSl 1.50

Dry Wear of Carbon-Graphite Materials Running Against
316 Stainless Steel.
Cambridge Univ. (England). 1982. 60pp.
PB84-107275/CAO  PC$13.50/MF$13.50

Mathematics & Statistics

CONTROL:  A   Suite  of  Interactive Transfer-Function
Analysis Programs.
Oxford Univ. (England). 1984. 41pp.
PB84-235639/CAO  PC$ 11.50/MF$ 11.50

Adaptive Algorithms  for  Estimating  Eigenvectors  of
Correlation Type  Matrices.
Helsinki Univ. of Technology, Espoo (Finland).  1983.
25pp.
PB84-196294/CAO  PC$9.50/MF$6.50
New  Approach  to Failure  Detection  in  Large  Scale
Systems.
University of Manchester Inst. of Science and Technology
(England). Oct. '81, 28pp.
PB84-160159/CAO  PCS 11.50/MF$ 11.50

Analogy and Mathematical  Reasoning: A Survey.
Leeds Univ. (England). May  '83, 62pp.
PB84-144401/CAO  PC$13.50/MF$13.50
HP67 and HP97  Calculator Programs for  Elementary
Statistical Calculations (Also  Compatible With the HP41-
Q.
Oxford Univ. (England). 1982. 120pp.
PB84-140474/CAO  PC$15.50/MF$15.50

Multigrid Methods: Development of Fast Solvers.
Technische Hogeschool, Delft (Netherlands). 1983. 26pp.
PB84-115609/CAO  PC$11.50/MF$6.50

Recursive  Estimation  of  Eigenvectors  of  Correlation
Matrices.
Helsinki Univ. of Technology, Espoo  (Finland).  1983.
18pp.
PB84-112598/CAO  PC$9.50/MF$6.50

Social Sciences

Database Packages for Microcomputers  Reviewed:  Com-
puters in Manpower Management.
Sussex Univ.,  Brighton (England).  1983. 29pp.
PB84-233949/CAO  PC$11.50/MF$11.50

Robots and People.
Univ.  of  Manchester  Inst.  of Science  and Technology
(England). Nov.  '81, 21pp.
PB84-232214/CAO  PC$9.50/MF$9.50

Non-Use of Library-Information Resources  at the Work-
place: A Comparative  Survey of Users and  Non-Users of
Onsite Industrial-Commercial Services.
Aslib, London (England). 1984. 169pp.
PB84-203769/CAO  PC$19.50/MF$19.50

Outline of a Study on the Relationship between Technical
Innovation and Labor.
Ministry of Labour, Tokyo  (Japan). Apr. '84,  161pp.
PB 84-174937/C AO  PC$21.50/MF$21.50

Mismatch between Machine  Representations and  Human
Concepts:  Dangers and Remedies. FAST Series No. 9.
Commission of the European  Communities,  Luxembourg.
1983. 164pp.
PB84-169101/CAO  PC$19.50/MF$19.50

Effects of Microelectronics  on Employment.
Ministry of Labour, Tokyo  (Japan). Oct.  '83, 138pp.
PB84-111996/CAO  PC$19.50/MF$19.50

Designing Automated Systems  Need Skill Be Lost.
Univ.  of  Manchester  Inst.  of Science  and Technology
(England). Aug.  '83, 17pp.
PB84-232297/CAO  PC$9.50/MF$9.50

Structural Engineering

Behaviour of  a  Lined Circular Tunnel in Viscoelastic
Ground.
Sydney Univ. (Australia). Jun. '83, 46pp.
PB84-131408/CAO  PC$11.50/MF$6.50
                                                                                                          7

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NTIS
Announces
foreign patent rights. Each invention is fully described in
one of 43 invention summary sections and cross referenced
where appropriate. Detailed subject and inventor indexes
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Reports on AIDS
This publication includes all the articles related to AIDS
that have appeared in the Morbidity and Mortality Weekly
Report, published by the Centers for Disease Control.
These articles, arranged in chronological order, track the
reporting of information on  AIDS from 1981, when CDC
first  published  information on Kaposi's  sarcoma  and
Pneumocystis  carinii  pneumonia  occurring  in  young
homosexual men.  In 1981,  CDC formed a task force to
establish risk factors, carry out laboratory  studies, and
disseminate timely information on the disease now known
as the acquired immunodeficiency syndrome (AIDS).
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Catalog of Government Patents
Some  1,400 inventions (patents granted or applied for in
1984) present opportunities for licensing in this new edition
of a unique annual catalog. The Catalog offers businesses
and entrepreneurs opportunities to license  and market
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The Abstract Newsletter, Foreign Technology, will soon
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Other subcategories of potential interest to industry are:
Biomedical Technology; Civil Construction, Structural and
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nology; Electro and Optical Technology; Energy; Manufac-
turing and  Industrial  Engineering; Materials Sciences;
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nology.

This new subject area covers the mining and processing of
metallic  and non-metallic resources.  It includes  coal
mining; coal preparation; petroleum exploration,  drilling,
and production; metals exploration and mining; mine safety;
mineral economics; and natural resources studies. Some of
the major sources of the documents cited include the British
Geological Survey, Christian  Michelsen's Institute (Nor-
way), Commission of the European Communities, Council
for Mineral Technology (South Africa), and Science and
Technology Agency (Japan).
Order PB85-903900/CAO for an annual  subscription at
$90.
Behaviour of Foundations Supported by Clay Stabilised by
Stone Columns.
Sydney Univ. (Australia). Nov. '82, 35pp.
PB84-132141/CAO  PC$11.50/MF$6.50

Engineering Design and the Perq.
Science  and  Engineering  Research  Council,  Chilton
(England).  1983. 34pp.
PB84-109289/CAO  PC$11.50/MFS11.50

Animating Forced Response of Structures.
Science  and  Engineering  Research  Council,  Chilton
(England).  1983. 15pp.
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Transportation

Meaning of Car Availability in Mode Choice Decisions.
Oxford Univ. (England).  1983. 19pp.
PB84-234772/CAO  PC$9.50/MF$9.50
Opportunities for Automobile Fuel Economy Arising from
New Technology and Design.
Open Univ., Milton Keynes (England). Feb. '84, 37pp.
PB84-205681/CAO  PC$11.50/MFSl 1.50

Transport Trends and Forecasts,
Oxford Univ. (England). Mar. '80, 17pp.
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Handbook of Toxicity of Pesticides to Wildlife.
Nearly 200 different chemicals or formulations, plus 15
other environmental pollutants, were tested on one or more
of some 30 different species in compiling this new edition
(the first update, in more than a decade) of the Handbook.
The pesticides were tested for both immediate and long term
(30 day) effect and were representative of common families
of chemicals used in thousands of formulations. Both oral
and percutaneous effects were tested and acute toxicity data
and a list of the clinical signs of intoxications are included.
The Handbook gives fish and wildlife resource managers a
convenient, reliable means for assessing potential contami-
nant threats to wildlife resources.
PB85-116267/CAO PC$11.50/MF$4.50
A Competitive Assessment of the U.S. Manufacturing
Automation Equipment Industries.
The report presents the following principal findings:
   The U.S. machine tool  industry has experienced a
   severe decline in its competitive position in the past
   several years.
   U.S. industrial robot manufacturers have also suffered
   from foreign competition, but are recovering through
   international joint ventures.
   U.S.  CAD/CAM manufacturers are benefiting from
   the move to automation by all manufacturing sectors.

Published by the International Trade Administration of the
U.S. Department of Commerce, the report elaborates on
current trends in automation equipment, the future of
international competition,  and the  implications of these
factors for the United States, as well as U.S. Federal policy
options. A glossary, bibliography, and some 30 tables and
figures are included.
PB85-103919/CAO PC$13/MF$4.50
Low Cost Bridge Deck Surface Treatments.
The  Federal Highway  Administration  sponsored  th
research to  discover bridge deck seal materials offerin
lower in-place cost and more effective resistance to wat<
penetration than the customary preformed membrane. Th
report identifies and describes the testing and analysis c
three effective  alternatives to preformed membrane. Si
materials were laboratory tested and evaluated includin
their effect on water absorption, resistance to de-ice
scaling, and adhesion of asphaltic concrete. Three promi:
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Also, more than 80 Federal Technical Information Center
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Federal sources of technical and business assistance. T<
request a FREE copy of this publication, write to NTIS
Springfield,  VA 22161, and request PR-767/745.

Robot Manipulators: Program  Control.
1975-September, 1984.
This Published Search is a bibliography containing 100 nev
citations (plus 226 earlier citations) concerning the contro
of robot manipulators. Industrial, commercial, personal
and medical applications are cited. Modeling and synthesi
for robotic programmable manipulative machinery contro
systems,  and development of numerical algorithms fo

-------
robot limb control computer software are emphasized for a
variety of tasks with a wide range of difficulty  factors.
These citations are the  product of a computerized online
search  on the  INSPEC  Information Services  for the
Physics and Engineering Communities  database.
PB84-875384/CAO  PC$40/MF$40

Social Indicators for Planning and Evaluation.
Originally produced for the U.S. Department of  Labor's
Employment and  Training Administration,  this report
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Mini/arms: Farm Business or Rural Residence.
Economic Research Service, Washington, DC.  Sep '84,
23pp.
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Nutrition Education for the Elderly. Volume 1. Final
Report.
Westinghouse Public  Applied Systems, Columbia, MD.
Nov '81, 186pp.
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Nutrition Education for the Elderly. Volume 2. Results of
the Pretest Survey.
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Nutrition Education for the Elderly. Volume 3. Results of
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Irrigation with Reclaimed Municipal Wastewater  A
Guidance Manual.
California State Water  Resources  Control  Board, Sac-
ramento. Jul '84, 521pp.
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Foreign Agricultural Trade of the United States (FATUS),
September/October 1984.
Economic Research Service, Washington, DC.  Oct '84,
93pp.
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Technology Assessment of Biological Nitrogen Fixation in
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 Optical Fiber Communications Link Design in
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 National Telecommunications and Information Administra-
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 Toward the Prevention of Alcohol Problems:
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 Technical Digest  Symposium on Optical Fiber
 Measurements,  1984.
 National Bureau of Standards (NEL), Boulder,  CO. Oct
 '84, 150pp.
 PB85-114700/CAO  PC$14.50/MF$4.50
 10

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              THE ROLE OF
         METRICS
         IN  US.  EXPORTS
A MAJOR NEW REPORT FROM THE U.S. DEPARTMENT OF COMMERCE
 To what extent is it necessary for
 U.S. manufacturers to produce
 in metric to maintain or penetrate
 foreign markets?

 Do foreign measurement prac-
 tices act as non-tariff barriers
 to U.S. exports?

 How does measurement enter
 into export decisions?

 How can measurement problems
 for export trade be reduced?

 To what extent will metric con-
 version further open U.S. markets
 to foreign goods?

 How much U.S. trade is mea-
 surement sensitive?

Comprehensive, authoritative
answers to these important
questions are provided in THE
ROLE OF METRICS IN U.S.
EXPORTS , prepared for the Office
of Metric Programs, U.S. Depart-
ment of Commerce. This landmark
study reports on all aspects of
metric conversion  from policy
issues, to a thirty-year outlook for
U.S. business in world trade, to
case histories of individual in-
dustries.

 Learn How Other  Industries Are
Meeting the Challenge of Metric
Competition

CASE 1 - Logs, Lumber, and Wood
Products

CASE 2 - The Construction and
Engineering Service Industry

CASE 3 - The Processed Food
Industry

CASE 4 - The Aerospace Industry
ORDER COMPLETE SET
OR INDIVIDUAL VOLUMES
The complete report consists of
ten paperbound volumes plus a one
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FOR COMPLETE SET ORDER:
PB84-235126/CAO SET, THE
ROLE OF METRICS IN U.S.
EXPORTS, $91, (11 paperbound
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FOR  INDIVIDUAL VOLUMES,
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              OTf  *

-------
              Computers
           Manufacturing
Guideline on Software Maintenance. Category: Software.
Subcategory: Software Maintenance.
National Bureau of Standards, Gaithersburg, MD. Jun '84,
25pp.
FIPSPUB 106/CAO  PC$7/MF$4.50
Microcomputers in Transportation: Addressing
Organizational Issues. Volume 3. Selected Readings.
Transportation Systems Center, Cambridge, MA. Sep '84,
135PP.
PB85-134732/CAO   PC$14.50/MF$4.50
                  Energy
Research and Development Activities in Geothermal
Drilling, Completion and Logging.
Sandia National Labs., Albuquerque, NM. 1984, 5pp.
DE84-016110/C AO  PC$7/MF$4.50
Technology of High-Level Nuclear Waste Disposal:
Advances in the Science and Engineering of the
Management of High-Level Nuclear Wastes. Volume 2.
Department of Energy, Oak Ridge, TN. 1982, 383pp.
DE82-009593/CAO  PC$17.75/MF$4.50
Interagency Advanced Power Group Project Briefs by
Field of Interest and a Subject Index: Semiannual
Compilation.
Interagency Advanced Power Group, Ft. Belvoir, VA. Sep
'84, 77pp.
PB85-102861/CAO  PC$11.50/MF$4.50
Heating and Climatisation: Review of Research, 1983.
Conseil  International du  Batiment pour la Recherche
1'Etude et al Documentation,  Rotterdam (Netherlands).
1983, 222pp.
PB85-118669/CAO  PC$23.50/MF$4.50
DOE (Department of Energy) Patents Available for
Licensing: A Bibliography.
Department of Energy, Oak Ridge, TN. Jun '82, 280pp.
DE82-012479/CAO  PC$17.00/MF$4.50
Air Infiltration and Heat Exchange.
Institute of Gas Technology, Chicago, IL. Nov '84, 62pp.
PB85-135275/CAO  PC$10/MF$4.50
       Electrotechnology
Damage Levels for Voltage Transients Applied to
Semiconductor Devices.
ERA Technology Ltd., Leatherhead (England). May '82,
71PP.
ERATL-85/07/CAO  Price: PCS4.50/MF not available
Robotic Technology: An Assessment and Forecast.
DHR, Inc., Washington, DC. Jul '84,  183pp.
AD-A146 672/CAO  PC$17.50/MF$4.50
Computational Mechanics: A Perspective on Problems and
Opportunities for Increasing Productivity and Quality and
Engineering.
National Research  Council, Washington, DC.  Oct '84,
75pp.
PB85-128106/CAO  PC$10/MF$4.50
Robotic Safety.
Sandia National Labs., Albuquerque, NM. May  '84, 9pp.
DE84-012237/CAO  PC$7/MF$4.50
Factors Affecting the Competitive Position of Natural Gas
in Industrial Heat Applications.
Energy and Environmental Analysis, Inc., Arlington, VA.
Sep '84, 178pp.
PB85-149805/CAO  PC$17.50/MF$4.50
               Materials
Technological  and Economic  Assessment of Advanced
Ceramic Materials. Volume 1. Summary and Conclusions.
Charles River  Associates, Inc., Boston, MA. Aug '84,
79pp.
PB85-113082/CAO  PC$11.50/MF$4.50
EPA (Environmental Protection Agency) Method Study 28,
PCB's (Polychlorinated Biphenyls) in Oil.
Versar, Inc., Springfield, VA. Oct '84, 91pp.
PB85-115178/CAO  PC$11.50/MF$4.50
           Environmental
Agricultural Sector Benefits Analysis for Ozone: Methods
Evaluation and Demonstration.
Resources for the Future, Inc., Washington, DC. Jun '84,
261pp.
PB85-119477/CAO  PC$22/MF$4.50
Capital  and O  and M (Operation'Maintenance) Cost
Relationships for Hazardous Waste Incineration.
Acurex Corp., Mountain View, CA. Oct '84, 217pp.
PB85-121119/CAO  PC$19/MF$4.50
Construction Grants   1985:  Municipal Wastewater
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Environmental Protection Agency, Washington, DC.  Jul
'84, 403pp.
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12

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California  State Water  Resources  Control Board, Sac-
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PB85-121457/CAO  PCS37/MF$4.50
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cals: Implementation Plan.
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Nationwide Urban Runoff Program, Washington, DC. Area
Urban Runoff Project: Final Report.
Metropolitan Washington Council  of  Governments, DC.
Dec '83, 199pp.
PB85-122133/CAO   PC$17.50/MF$4.50
Water  Distribution  System  as a  Potential Source  of
Mutagens in Drinking Water.
Syracuse Research Corp., NY. Nov '84,  205pp.
PB85-125474/CAO   PC$19/MF$4.50
Adjustment  of Incidence Rates for Migration in Indirect
Ecologic Studies.
California Univ.,  Berkeley. Nov '84, 80pp.
PB85-124139/CAO   PC$11.50/MF$4.50
Health Assessment Document for Carbon Tetrachloride.
Environmental  Protection Agency,  Cincinnati, OH.  Sep
'84, 321pp.
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Asbestiform Fibers: Nonoccupational Health Risks.
National Research Council, Washington, DC. Feb '84,
354pp.
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Evaluation of the Asbestos-in-Schools Identification and
Notification Rule.
Battelle  Columbus  Labs., Washington,  DC. Oct '84,
245pp.
PB85-135085/CAO   PC$20.50/MF$4.50
Asbestos in Buildings: A  National Survey of Asbestos-
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236pp.
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Overview of Major Wetland Functions and Values.
Creative Consulting Corp. International, Fort Collins, CO.
Sep '84, 77pp.
PB85-119907/CAO   PC$11.50/MF$4.50

Value Engineering for Wastewater Treatment Works.
Weston (Roy F.) Inc., West Chester, PA. Sep '84, 132pp.
PB85-135622/CAO   PC$14.50/MF$4.50
Chemical Substances Information Network  (CSIN):  An
Overview.
Interagency Toxic Substances Data Committee, Washing-
ton, DC.  1984, 29pp.
PB85-135812/CAO   PC$8.50/MF$4.5()
Indoor Air Quality: 20 Existing Homes.
Beak Consultants Ltd., Toronto (Ontario).  Jun '84, 129pp.
PB85-135382/CAO   PC$17.50/MF$6.50
National Marine Pollution Program: Catalog of Federal
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National Marine Pollution Program Office, Rockville, MD.
Sep '84, 328pp.
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National Marine Pollution Program: Catalog of Federal
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Jul '82, 450pp.
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Potential Office Hazards and Controls.
Wisconsin Univ., Madison. Sep '84, 187pp.
PB85-139210/CAO   PC$17.50/MF$4.50
14

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Hotline:
International  Food  Policy  Research
Institute  (IFPRI)
Established in  1975,  the International  Food Policy
Research Institute (IFPRI) conducts policy research on food
production, consumption,  and trade, with emphasis on
low-income countries. NTIS has entered into an agreement
with IFPRI to include their reports in the NTIS Database.
All 46 reports, whose titles appear  below, are available
from NTIS in microfiche form only. Paper copy is available
from IFPRI at  1776  Massachusetts  Avenue, N.W.,
Washington, DC 20036.
Meeting  Food Needs in  the Developing  World: The
Location and Magnitude of the Task in the Next Decade.
PB85-167633/CAO  Price:MF$4.50

Recent and Prospective Developments in Food Consump-
tion: Some Policy Issues.
PB85-167385/CAO  Price: MF$4.50

Food Needs of  Developing Countries:  Projections of
Production and Consumption to 1990.
PB85-167377/CAO  Price: MF$4.50

Food Security: An Insurance Approach.
PB85-167492/CAO  Price: MF$4.50

Impact of Subsidized Rice on Food Consumption and
Nutrition in Kerala.
PB85-167484/CAO  Price: MF$4.50

Intersectoral Factor Mobility and Agricultural Growth.
PB85-167468/CAO  Price: MF$4.50

Public Distribution  of  Foodgrains in Kerala  Income
Distribution Implications and Effectiveness.
PB85-167427/CAO  Price: MF$4.50

Foodgrain Supply, Distribution, and Consumption Policies
within a  Dual Pricing Mechanism:  A  Case Study of
Bangladesh.
PB85-167401/CAO  Price: MF$4.50

Brazil's Minimum Price Policy and the Agricultural Sector
of Northeast Brazil.
PB85-167419/CAO  Price: MF$4.50

Investment and Input Requirements for Accelerating Food
Production in Low-Income Countries by 1990.
PB85-167435/CAO  Price: MF$4.50

 Rapid Food Production Growth  in Selected Developing
 Countries: A Comparative Analysis of Underlying Trends,
 1961-76.
 PB85-167443/CAO  Price: MF$4.50
Two  Analyses  of  Indian  Foodgrain  Production  and
Consumption Data.
PB85-167450/CAO  Price: MF$4.50

The Impact of Public Foodgrain Distribution on Food
Consumption and Welfare in Sri Lanka.
PB85-167658/CAO  Price: MFS4.50

Developed-Country Agricultural Policies and Developing-
Country Supplies: The Case of Wheat.
PB85-167641/CAO  Price: MF$4.50

Food Production in the People's Republic of China.
PB85-166403/CAO  Price: MF$4.50

Agricultural Research Policy in Nigeria.
PB85-166395/CAO  Price: MF$4.50

The Economics of the International Stockholding of Wheat.
PB85-166700/CAO  Price: MFS4.50

A  Comparative  Study  of FAO and USDA Data  on
Production, Area, and Trade of Major Food Staples.
PB85-166718/CAO  Price: MFS4.50

Impact of Irrigation and Labor Availability on Multiple
Cropping: A Case Study of India.
PB85-166734/CAO  Price: MF$4.50
 Agricultural Protection  in OECD Countries: Its  Cost to
 Less-Developed Countries.
 PB85-166726/CAO   Price: MF$4.50

 Estimates of Soviet Grain Imports in  1980-85: Alternative
 Approaches.
 PB85-166742/CAO   Price: MF$4.50

 Government Expenditures on Agriculture in Latin America.
 PB85-166387/CAO   Price: MF$4.50

 The Effects of Exchange Rates and Commercial Policy on
 Agricultural Incentives in Colombia: 1953-1978.
 PB85-166379/CAO   Price: MF$4.50

 Instability in Indian Agriculture in the Context of the New
 Technology.
 PB85-166411/CAO   Price: MF$4.50

 Food Security in the Sahel: Variable Import Levy, Grain
 Reserves, and Foreign Exchange Assistance.
 PB85-166361/CAO   Price: MF$4.50

 Agricultural Price Policies Under Complex Socioeconomic
 and Natural Constraints: The Case of Bangladesh.
 PB85-165199/CAO   Price: MFS4.50

 Growth and Equity: Policies and Implementation in Indian
 Agriculture.
 PB85-165264/CAO   Price: MF$4.50
                                                                                         15

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Government Policy and Food Imports: The Case of Wheat
in Egypt.
PB85-165256/CAO  Price: MFS4.50

Instability in Indian Foodgrain Production.
PB85-167393/CAO  Price: MF$4.50

Sustaining Rapid Growth in India's Fertilizer Consumption:
A Perspective Based on Composition of Use.
PB85-165249/CAO  Price: MF$4.50

Food  Consumption Parameters for  Brazil  and Their
Application to Food Policy.
PB85-165231/CAO  Price: MF$4.50

Agriculture Growth and Industrial Performance in India.
PB85-165223/CAO  Price: MF$4.50

Egypt's Food Subsidy and Rationing System: A Descrip-
tion.
PB85-165215/CAO  Price: MF$4.50

Policy Options for the Grain Economy of the European
Community: Implications for Developing Countries.
PB85-165207/CAO  Price: MF$4.50

Agriculture and Economic Growth in an  Open Economy:
The Case of Argentina.
PB85-165298/CAO  Price: MFS4.50

Service Provision and Rural Development in India: A Study
of Miryalguda Taluka.
PB85-166239/CAO  Price: MFS4.50

Policy Modeling of a Dual Grain  Market: The Case of
Wheat in India.
PB85-166247/CAO  Price: MF$4.50

The World Rice Market: Structure, Conduct, and Perform-
ance.
PB85-166254/CAO  Price: MFS4.50

Food  Subsidies in Egypt:  Their Impact  on  Foreign
Exchange and Trade.
PB85-166262/CAO  Price: MFS4.50

Rural Growth Linkages: Household Expenditure Patterns in
Malaysia and Nigeria.
PB85-166270/CAO  Price: MF$4.50

The Effects of Food Price and Subsidy Policies on Egyptian
Agriculture.
PB85-166296/CAO  Price: MFS4.50

Closing the Cereals Gap with Trade and Food Aid.
PB85-166288/CAO  Price: MFS4.50

Constraints on Kenya's Food and Beverage Exports.
PB85-166213/CAO  Price: MFS4.50

The Effects of the Egyptian Food Ration and Subsidy
System on Income Distribution and Consumption.
PB85-166205/CAO Price: MFS4.50

The Effects  on Income Distribution and Nutrition of
Alternative Rice Price Policies in Thailand.
PB85-166221/CAO Price: MF$4.50

Evolving Food Gaps in the Middle East/North Africa:
Prospects and Policy Implications.
PB85-167476/CAO Price: MFS4.50
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is now available. Published by the Center
for the  Utilization of Federal Technology
(CUFT),  located at NTIS, the  Catalog
describes practical technology selected
for commercial potential and/or promis-
ing applications in various fields.
  This  exciting  source describes some
1,200 new processes, inventions, equip-
ment,  software,  and  techniques  de-
veloped  by and  for dozens of Federal
agencies during 1984.
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summaries of this practical  technology
into 24 broad disciplines for easy brows-
ing. Sources of additional information are
given for each summary and a thorough
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Price: $23.50, plus $3 handling.
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 16

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DataBase
News
For more information on the database items described
below, please telephone Stuart Weisman (703) 487-4808.


New data files from the Energy Information Administration
(ElA) contain surveys of producers, transporters, storage
facilities, exporters and  importers  of crude oil  and
petroleum products, and from the Census Bureau and State
conservation agencies. Approximately one-quarter million
unique data records reflecting the U.S. Petroleum Balance,
Supply and Disposition, Production and Movement of crude
oil and petroleum products will be accumulated each year.

The new Public-Use Tape expands the survey data in the
publication Petroleum Supply Monthly by providing a series
of data files that can be manipulated by users. Data records
are reported  on  a  monthly basis, and the tape release
includes all months to date for the current year (1984). An
annual  tape release is also available containing twelve
months of revised aggregate data for the previous calendar
year (1983).
Geographic units represented on the tape are at the level of
USA, Petroleum Administration for Defense District
(PADD), Sub-PADD, or Refinery District. There are two
exceptions: Domestic Crude Oil Production and combined
Stocks of Refinery  and Bulk Terminals are presented at
State-level.
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prepared in most standard 7 or 9 track recording modes for
one-half inch tape. Identify recording mode desired by
specifying character set, track density, and parity.
Order:   PB84-234418/CAO  Petroleum Supply
        Monthly (1984)  Price: $140
       PB84-233022/CAO  Petroleum Supply
        Annual (1983)  Price: $140
EIA has released the following updates to their existing
data files/models:
 Report of Oil Imports
   into the United States and Puerto
   Rico, forms EIA-814/EIA-815
   (January 1983-February 1984)
 Production of Onshore
   Lower-48 Oil and Gas Model
   (PROLOG82)
 National Coal Model
   (NCM4)
 International Coal Trade
   Model (ICTM83)
 Gas Analysis Modeling
   System (GAMS83)
 Evaluation of Uranium
   Resources and Economic
   Analysis (EUREKA4A)
 Short-Term Coal
   Analysis System (SCOAL 84B)
 Alternative Fuel Demand
   Due to Natural Gas
   Deficiencies/EIA-50,  1983-84
 Interstate Pipelines
   Annual Report of  Gas Supply,
   1981-83 (FERC-15)
 Electric Utility Company
   Monthly Statement/Historic
   (1977-83), EIA-826
PB84-191154/CAO
PB85-146926/CAO
PB85-146934/CAO
PB85-146942/CAO
PB85-146959/CAO
PB85-146967/CAO
PB85-146975/CAO
PB85-144772/CAO
PB85-128064/CAO
PB84-214535/CAO
Each of the above data files/models is priced at $140. For
information on data files from the EIA, request PR-712/745;
for details on EIA models, request PR-705/745.

The following data files from the National Center for Health
Statistics (NCHS) have recently been announced:
 Third Wave Prevalence         PB85-116168/CAO
   Findings from the Massachusetts           $140.
   Health Care Panel Study
                                               National Survey of
                                                 Family Growth, Cycle III,
                                                 (Combined Respondent/Internal
                                                 File, 1982)

                                               National Hospital Discharge
                                                 Survey, 1981
                           PB85-100022/CAO
                                     $140.
                           PB85-152338/CAO
                                     $240.

                                        17

-------
                               PB85-153658/CAO
                                           $140.
                               PB85-152304/CAO
                                           $140.
                               PB85-153633/CAO
                                           $985.
                               PB85-153591/CAO
                                           $140.
                               PB85-153625/CAO
                                           $320.

                               PB85-153617/CAO
                                         $1,180.
 National Hospital Discharge
    Survey, 1982
 National Hospital Discharge
    Survey, 1983
 Vital Statistics Natality
    Data, Detail, 1982
 Vital Statistics Natality
    Data, State Summary 1982
 Vital Statistics Natality
    Data, Local Area Summary,
    1982
 Vital Statistics Mortality
    Data, Multiple Cause Detail,
    1981
 NHANES II (National            PB85-153609/CAO
    Health and Nutrition Examination            $140.
    Survey, 1976-1980),
    Audiometric Air Conduction
    Test, Ages 4-19 years. Catalog
    number 5306
For information  on  these and other data files from the
National Center for Health Statistics, request PR-716/745.

NTIS  is  pleased to announce  the  availability  of the
following new data files produced by the Defense Logistics
Supply Center (DLSC). All DLSC data files are available as
a one-time demand order or as a standing order. They are
provided in various  formats on magnetic tape or on 5V41'
floppy diskette compatible with the IBM-PC.
  NATO Supply Code for
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  H8-1 & H8-2 Cataloging
   Handbooks
                                 PB85-172732/CAO
                                             $140
                                 PB85-172740/CAO
                                             $140
                                 PB85-120483/CAO
                                             $790
For descriptive information on the DLSC data files, request
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SIX NEW TITLES ADDED TO LIST OF DATA
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 World Data Bank II, Volume I/North          $1,395
  America (from the Central
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 Analyses of Natural Gases (from the            $270
  Department of the Interior)
 Power Plant Report/EIA-759: both the    $165 Current
  current (1984) and the 1983 extract      $210 Extract
  file  are available) (from the Energy
  Information Administration)
 Cost & Quality of Fuels for Electric     $210 Current
  Utilities/FERC-423: both the current     $240 Extract
  (1984)  and the 1983 extract file are
  available (from the Energy
  Information Administration)
 Nutritive Value of Food as in Home             $75
  & Garden Bulletin No. 72, Revised
  1981, Data Set 72-1 (from the U. S.
  Department of Agriculture)
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                        * Information Services in Mechanical Engineering (ISMEC)
                        *,fro^wOattM'pDB)        -.,'
                         Conference Papers Index (CONF)     ',
18
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             TABLE  2-4.   GROUNDWATER SAMPLING METHODS (WILSON 1980)
     Sampling  devices

          Tile 1ines
          Collection  pans  and manifolds
          Wells
          Piezometers
          Multilevel  samplers
          Groundwater  profile samplers

     Sample extraction methods

          Hand bailers
          Air-lift  and gas-lift  pumps
          Suction  lift pumps
          Piston pumps
          Centrifugal  pumps
          Submersible  pumps
     4.   Ground-water  Monitoring  Systems, Technical  Resource  Document (U.S.
Environmental  Protection  Agency, in  preparation); and

     5.  Ground-water Monitoring Guidance for Owners and Operators of  Interim
Status Facilities  (U.S. Environmental Protection Agency 1982b).

Cost estimates prepared by  the  U.S.  Environmental Protection Agency (1982) for
several types  of monitoring techniques  are presented in Table 2-5.

     Caution  should be  exercised  in  the choice  of well  casing material.
The selection  of  casing  depends on the  constituents  being  monitored.   Steel
casing may contribute such  contaminants  as zinc and  iron; therefore the use of
PVC,  fiberglass,  or teflon is recommended.   Wilson  (1980)  discusses  the
controversy of whether PVC  is appropriate for sampling of organic pollutants.
Dunlap et  al.  (1977) feel   that PVC adsorbs  organic  constituents  as  well  as
contributes such  contaminants  as  phthalic acid esters to samples.   However,
Geraghty  and  Miller, Inc.  (1977)  indicate  that PVC  does  not  leak  organic
compounds  and  is  more  inert than  steel  casing,  which  develops  an iron oxide
coating which has  an unpredictable  and  changeable  adsorptive  capacity.  With
PVC, once the  adsorption  sites  are saturated, the concentration of organics in
the water  remain  in equilibrium  with  the adsorbed organics.   For microbial
sampling, Wilson  (1980)  suggests the use of PVC pipe,  because metal constitu-
ents in steel  wells  could inhibit  microbial growth.

RUNOFF WATER MONITORING

     To ensure the health and safety of  off-site  populations, runoff water, if
any occurs, should be monitored for hazardous constituents or byproducts.   If

                                       7

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          TABLE 2-5.  COST ESTIMATES  FOR  VARIOUS  MONITORING TECHNIQUES AND CONSTRUCTION METHODS
                  IN THE ZONE OF  SATURATION  (U.S.  ENVIRONMENTAL  PROTECTION AGENCY  1982)


Monitoring technique &                                        Price per installation well  diameter
construction method                                   51 .mm (2-inch)    102mm (4-inch)     152mm (6-inch)

Screened over a single interval  (plastic  screen
  and casing)
  1.  Entire aquifer                                  $1,600-$3,700     $2,300-$4,500     $6,400-$7,500
  2.  Top 3 meters (10 feet)  of  aquifer                   600-  1,050        700- 1,150
  3.  Top 1.5 meters (5 feet) of  aquifer  with  drive       100-    200
      point

Piezometers (plastic screen & casing)
  1.  Entire aquifer screened
      a.  Cement grout                                 2,100-  4,700      2,800- 5,500      6,900- 8,500
      b.  Bentonite seal                               1,850-  4,150      2,350- 4,950      6,650- 7,950
  2.  Top 3 meters (10 feet)  of  aquifer screened
      a.  Cement grout                                 1,150-  2,050      1,200- 2,150
      b.  Bentonite seal                                 900-  1,500        950- 1,600

Well clusters
  1.  Jet-percussion
      a.  Five-well cluster,  each well with  a           2,500-  3,800
          6-meter (20-foot) long  plastic  screen
      b.  Five-well cluster,  each well with  only        1,700-  2,300
          a 1.5 meter (5-foot) long plastic  screen
  2.  Augers
      a.  Five-well cluster,  each well with  a  6-        4,600-  5,300
          meter (20-foot) long stainless  steel
          wire-wrapped screen
      b.  Five-well cluster,  each well with  only        1,800-  2,600
          a 1.5 meter (5-foot) long gauze wrapped
          drive points
  3.  Cable tool
      a.  Five-well cluster,  each well with  a  6-             -                  -            9,850-14,150
          meter (20-foot) long stainless  steel,
          wire-wrapped screen

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                                         TABLE  2-5.   CONTINUED
Monitoring technique &                                        Price per installation well  diameter	
construction method                                   51 mm (2-inch)102mm (4-inch)152mm (6-inch)


  4.  Hydraulic rotary
      a.  Five-well cluster,  each  well  with  a                -            9,050-14,900     13,800-19,400
          6 meter (20-foot)  long plastic  screen
          casing grounded in  place
      b.  Five-well cluster,  completed  in a  single     4,240- 5,800     8,250-11,000
          large-diameter borehole  4.5 meter  (15-
          foot) long plastic  screens, 1.5-meter
          (5-foot) seal  between screens
  5.  Single well/multiple sampling point                   -                 -            3,000- 4,700
      a.  33.5-meters (110-foot) deep well with
          1-foot long screens separated by  1.2
          meters (4-feet) of  casing starting
          at 3 meters (10-feet) below ground
          surface

Sampling during drilling                                    -            3,000- 4,700      3,300- 5,200


Note: Cost estimates are for  an aquifer composed of unconsolidated sand with a depth to water of 3
      meters (10 feet) and a  total saturated thickness of 30 meters (100 feet).  Cost estimates are
      based on rates prevailing in the  Northeast in Autumn, 1975.   Actual costs will be lower and higher
      depending upon conditions in other  areas.   Therefore, while  the costs presented will become out-
      dated with time, the relative cost  relationships among the monitoring techniques should remain
      fairly constant.

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significant  concentrations  are  found,  provisions  should  be  available  for
collecting,  storing, treating,  and/or  recycling  the water  through the  site.

AIR MONITORING

     Air monitoring  at hazardous waste sites is  essential for  the  protection
of health and safety of the remedial action team due to the  volatile nature of
many hazardous  compounds   anticipated  at hazardous  waste  sites.  An  adequate
air monitoring  program allows  the evaluation  of  the relative importance  of
vapor transport  from the  site,  provides a  means for evaluating  the  effective-
ness of  vapor suppression techniques,  permits  the  identification of  volatile
daughter products from the  various treatment  techniques utilized,  and is  a
requirement  if vapor  phase photolysis  is used  as  a treatment  alternative.

     In  addition to personal  monitoring equipment, a perimeter sampling
network should  be established to detect off-site migration of  gaseous  and/or
particulate  emissions.  Upwind  and downwind sampling sites should  also be used
to determine background air quality as well as the extent of off-site  contami-
nation,  if  any.   A large number  of  sources  are  available concerning  the
development  of  air  sampling  networks  from  both  the  USEPA and  professional
organizations  such as the Air  Pollution Control  Association, and these  enti-
ties should  be  contacted  for specifics.

     Both high-efficiency  particle filter  samplers  and  gas/vapor  samplers
should  be used  for contaminant collection  (Cheremisinoff  et  al. 1982).
Solid  sorbent  traps have  become  the   standard  sampling  medium for  volatile
organic air  pollutants (Seiber  and Woodrow 1983)  and  are  suggested for  mate-
rials  with  boiling  points greater  than  100C  (Cheremisinoff  et  al.  1982).

     Continuous   air  monitoring  during  normal  working  hours,  suggested  for
industrial  and  hazardous  waste  impoundments (Cheremisinoff et al.  1982),  would
be a minimum requirement  at hazardous waste sites with potentially significant
vapor  phase hazards.   Sites  with known significant  vapor  phase  hazard  would
require continuous air  monitoring  until hazard  mitigation is complete.

     Cheremisinoff et al.  (1982)  indicate that  a minimum  air monitoring
program should  include  the following analyses:

     1.   Organic compounds  with  boiling points  greater than  300"C, from
particulate  filter samplers.

     2.   Total   Chromatographable  Organic (TCO)  analysis for  compounds with
boiling points  from 100 to 300C from  solid sorbent samplers.

     3.  Mass Spec  analysis for  inorganic/element determinations  of materials
collected on particulate  filter samplers.

     4.   Analysis for specific  compounds of  concern based on specific site
information  via acceptable EPA  or NIOSH standard  procedures.

     Specific  constitutent  analysis  would  be  a  requirement  for  treatment
effective evaluation  and would indicate parent compound  destruction  and

                                      10

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reaction  product  formation  during  implementation  of  on-site  hazard  mitiga-
tion procedures.

REFERENCES

Bordner,  R.,  J.   Winter,  and  P.  Scarpino.    1978.    Microbiological  methods
     for  monitoring the  environment.   EPA-600/8-78-017.   U.S.  Environmental
     Protection Agency,  Washington,  D.C.

Brown,  K.  W.   and Associates,  Inc.    1980.   Hazardous waste  land  treatment.
     SW-874  (Draft)  U.S.  Environmental  Protection Agency,  Cincinnati,  OH.

Cheremisinoff,  N.  P.,  P. N.  Cheremisinoff,  F.  Ellerbush,  and A.  J   Perna.
     1982.  Industrial  and  hazardous  waste  impoundments.   Ann  Arbor  Science
     Publishing,  Inc., Ann Arbor,  MI.

Dunlap, W. J., J. F. McNabb,  M.  R.  Scalf,  and R. L.  Cosby.   1977.   Sampling
     for organic  chemicals  and microorganisms  in  the  subsurface.   EPA-600/2-
     77-176.   U.S.  Environmental  Protection Agency, Washington,  D.C.

Geraghty  and  Miller,  Inc.    1977.    The  prevalence of subsurface  migration
     of hazardous chemical substances  at selected  industrial  waste  land
     disposal   sites.   EPA/530/SW-634, U.S.  Environmental   Protection  Agency,
     Washington,  D.C.

Scalf,  M. R., J. F. McNabb, W.  J.  Dunlap, R.  J.  Cosby  and  J.  Fryberger.
     1981.  Manual of  ground-water  sampling procedures.  National Water
     Well  Association.,  Worthington, OH.  93 p.

Seiber, J. N., and J.  E.   Woodrow.   1983.   Methods  for  studying  pesticide
     atmospheric  dispersal   and  fate  at  treated  areas.   Pesticide  Reviews
     85:217-229.

U.S. Army  Corps of  Engineers.   1982.   Preliminary guidelines for selection and
     design of remedial   systems  for  uncontrolled  hazardous waste sites.   EM
     1110-2-(Draft).   Department  of  the  Army,  Corps  of Engineers,  Washington,
     D.C.

U.S.  Department  of the  Interior,  Bureau of  Reclamation.  1977.   Ground-
     water manual.   U.S.  Government Printing, Washington, D.C.

U.S. Environmental  Protection Agency.   1977.   Procedures   manual for  ground-
     water monitoring at solid  waste disposal  facilities.    SW-616.    U.S.
     Environmental Protection Agency,  Washington,  D.C.

U.S. Environmental Protection Agency.  1982a.  Handbook for remedial  action at
     waste disposal  sites.    EPA-625/6-82-006.  U.S. Environmental  Protection
     Agency, Cincinnati,  OH.

U.S. Environmental Protection Agency.  1982b. Ground-water  monitoring guidance
     for owners and operators  of  interium  status facilities.    SW-963.   U.S.
     Environmental Protection Agency,  Washington,  D.C.


                                      11

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U.S. Environmental  Protection  Agency.    1982c.   Test  methods  for  evaluating
     solid waste.   SW-846.   U.S. Environmental  Protection agency,  Washing-
     ton,  D.C.

U.S. Environmental Proection Agency.   1983.   Hazardous waste  land  treatment.
     SW-874,  U.S.  Environmental  Protection  Agency,  Cincinnati,  OH.

Vanhoff,  J.  A.,  K. U.  Weyer,  and S.  H.  Whitaker.  1979.   Discussion of  "A
     multilevel  device  for ground-water sampling  and  piezometric  monitoring
     by J. F.  Pickens,  J.  A.  Cherry,  G.  E.  Grisak,  W.  F.   Merritt, and  B.
     A. Rizto."   Groundwater 17(4):391-393.

Wilson, L. G.   1980.   Monitoring in the vadose  zone:   A review of  technical
     elements and  methods.  EPA-600/7-80-134,  U.S.  Environmental  Protection
     Agency,  Las Vegas,  NV.
                                      12

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                                   SECTION 3

                CHARACTERIZATION AND EVALUATION OF  FUNDAMENTAL

                        PROCESSES IN SOIL/WASTE SYSTEMS


SITE AND SOIL FACTORS RELATED TO IN SITU TREATMENT

Introduction

     Identification of site characteristics is  necessary before  the initiation
of  in  situ  remedial  actions for  treatment  of  hazardous  waste  contaminated
soils for three reasons.   First, residual  hazardous constituents are  of  public
health concern  because of  their  ultimate  abil'ity to  contaminate the  atmo-
sphere, through volatilization  or  resuspension, and the hydrosphere, through
leaching  and  runoff  (Dawson  and  Brown  1981).   Thus  to  protect  the  public
health, both route characteristics  by which the contaminant migrates  off-site,
and off-site receiver characteristics must be  considered.   Route characteris-
tics determine the potential  for contamination,  while receiver characteristics
and the corresponding degree  of public  health  hazard indicate  the time  frame
in  which  the remedial  action must  be performed.   Site  characterization  also
may serve to  elucidate  aspects  of  site modification or  management to improve
protection of human health.

     In determining  the  public  health hazard  potential,  both  site  and  waste
characteristics must  be  integrated.    For example, if site characteristics
indicate an immediate public health hazard due to  high  potential  for off-site
migration of an extremely hazardous chemical,  an expensive  but  rapidly  acting
chemical   in  situ  treatment technique may be  more  appropriate  than a  slower
acting, less expensive technique utilizing natural  soil  processes.

     Figure 3-1 depicts transport,  decomposition, and immobilization  processes
influencing the  migration of  hazardous  constituents in the  environment.
Hazardous  compounds  can  be   dispersed  through  the atmosphere  via airborne
particles or as gases.  Human exposure occurs  directly  through  dermal contact
and inhalation of  particles  or  gas or indirectly through  deposition on  crops
or bioaccumulation in grazing game  and agricultural  animals, either or both  of
which may be ingested by humans. Hazardous compounds may reach  surface  waters
in runoff, either dissolved or  suspended  in water  or adsorbed to eroding  soil
particles.  Movement through  the soil may  occur as  liquid  or gas or  dissolved
in  soil water  both in lateral  and vertical  directions  to ground  and surface
waters.   Human  contact occurs  through  ingestion  of the contaminated   water.
For purposes of this manual,  detoxification by  plants or removal  in vegetation
are not considered as means of in situ treatment.
                                      13

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                                   Detoxification
                                   Removal in
                                   Vegetation
 Decomposition
                           o^^/Sorption7
 0
  o  )  Biological
                                            \Precipitaton    Degradation
                               Capillary
                                 Flow
           Groundwater
Figure 3-1.  Processes influencing the migration of hazardous  constituents in the terrestrial environ-
             ment (adapted from Weber et al. 1973).

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     Decomposition and  transformation  of compounds  may occur  by biological
processes,  by chemical means  (e.g.  oxidation,  reduction,  hydrolysis)  or
by  photodecomposition  at the  soil  surface.    Degradation  refers  to  changes
from hazardous  to less  hazardous or  innocuous  substances,  while transforma-
tion refers to changes  from  hazardous  to less  toxic or innocuous substances.
Compounds may be  also  immobilized by  adsorption  to  soil particles, which may
either be organic materials,  such  as humus or inorganic materials, such as the
clays montmorillonite,  vermiculite, or  the hydrous oxides.

     Secondly,  the site must  be evaluated in  terms of  its  potential  for
decreasing  the  degree  of  hazardous  of  contaminants by degradation,  trans-
formation and  immobilization.   This aspect of site characterization focuses on
soil  physical,   chemical,  and  biological  properties  and  on  climatological
variables.  The  choice  of  a  particular in  situ treatment technology or train
of  treatments  and its   (their) effectiveness  is often  highly  dependent  on
site/soil characteristics as  well  as on waste characteristics.

     The  third  aspect  of site  characterization concerns the  actual  physical
execution of  the treatment  techniques.   Trafficability of  the  site  (steep
slopes, excessively wet  conditions, soils high  in sticky, plastic clays, etc.)
may affect  the choice of an  appropriate  treatment or the manner in which the
in  situ  treatment  is  conducted, or may even  preclude the use  of any  in  situ
treatment method.   Appropriate site  modifications  and  management  options  to
enhance treatment are  dependent  upon the  existing site conditions.

     In many instances,  data  needs for  off-site migration potential, treatment
choice and effectiveness, and treatment execution  may overlap,  but the use of
particular  types of  data should be  kept in  mind  while  investigating  and
characterizing  a site.   This  will ensure that  data  are  collected in an inte-
grated manner  and that necessary data are collected.  At sites where previous
remedial   actions  have  removed  acute  hazards  but contaminated  soils with  low
levels  of hazardous constituents remain,  a preliminary assessment of available
information  may  indicate that existing data are  sufficient  and few or no new
characterization  efforts are  required.

Site Characterization  Related  to Off-site Migration

     Site characteristics  that relate  to  potential  for off-site  migration
of  hazardous  compounds include  a)  site location  and topography; b)  soil
properties;  c)  geological  factors;  d)  hydrogeological  factors;  and  3)  cli-
matological  factors.

Site Location  and Topography--
     Potential  for  contaminant migration  due  to  soil  permeability,  depth
to groundwater,  credibility,  and flooding potential can sometimes be predicted
by  knowledge of  the  type of  landform  on which  the hazardous waste  site  is
located  (Table 3-1).   The type of  landform  may also indicate  possible  site
modifications necessary to minimize  migration  (Phung et  al.  1978).   For
example,  on  upland crests and valley  side landforms, surface  water is  limited
to  incident precipitation and controllable off-site  runoff.   These landforms
may require the  diversion of  surface  waters  to reduce  the  amount of  water
entering   and infiltrating the  site.   However,  upland crests or  valley sides


                                     15

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 TABLE 3-1.   LANDFORMS AND TOPOGRAPHY OF HAZARDOUS WASTE SITES AS RELATED TO
                     POTENTIAL FOR MIGRATION OF HAZARDOUS CONSTITUENTS
                       (ADAPTED FROM RYAN AND LOEHR 1981)
Landscape Position:
    Topography
Outwash plains: near level
     broad tracts gently
     sloping from origin

Terraces: flat areas with
     stair-stepped develop-
     ment, commonly between
     river and upland:
          glacial
          marine

          lake

Lake beds: broad,
     exceptionally f1 at

Till plains: young-broad,
     gently roll ing
     old-broad, level
     areas

Alluvial fans:  smooth
     moderate slopes,
     transitional area
     between highlands
     and lowlands

Playas: broad, exceptionally
     flat surfaces

Loess: undulating topography
     with smoothly rounded
     convex hills

Moraine
         Migration Potential
   GroundwaterErosion
Eskers: long, low, narrow
steep-sided ridges
Kames: low, long, steep-
sided ridges
high permeability
high permeability
steep
slopes
steep
slopes
potential  high water-
  table,  especi al ly on
  fringe
high permeability
high to moderate
  permeability
low permeabi1ity

low permeability
high watertable

high watertable

moderately deep
  watertable

high permeability
potential high water-
  table at bottom of
  fan
low permeabi1ity
moderate
permeabi1ity
highly heterogeneous -
    moderate
    slopes
    high erosion
    potential

more investigation
required
                                      16

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                            TABLE 3-1.  (continued)


Landscape Position:                        Migration  Potential
    Topography                       Groundwater             Erosion


Floodplain                                                   flooding

Delta                                                       flooding

Beach ridges                      high groundwater

Coastal  plains                    highly heterogeneous -  more investigation
                                                        required

Tidal flat                                                   flooding

Sand dunes                                                   wind
                                                            erosion
                                                            potential
may  pose  a high hazard to  groundwater  since  they  are often in  groundwater
recharge areas.

     Upland flat  areas with  fine-grained soils  of low permeability pose
less  risk of high  groundwater  and  erosion  and  have greater  attenuation
capacities than  terrace  landforms.    Terrace  landforms  are often  underlain
by  highly permeable  coarse-grained soils,  sometimes  at shallow depths.
Contamination  from  these  sites  may  occur  at  nearby surface expressions of
underlying groundwater.   The  probability of  groundwater intersecting a
terrace  site  increases  as  the  site  position  approaches  either  the  valley
wall or the level of the modern floodplain.

     Warner  (1976)  describes  four  site conditions  where  pollution  poten-
tial is especially high.  They are as follows:

     1.   Sloping  sites with  relatively impermeable bedrock  (e.g. shale,
dense  limestone, crystalline  igneous  rock)  0.6 m  or less from  the  surface
--high  potential for erosion,  seepage  and  overland flow  of  contaminated
effluent.

     2.   Sites located  in karst  topography,  with clayey residual soils
overlying limestone or dolomite with  fracture and solution  porosity  and
permeability -  high potential  for contamination of  groundwater, for  though
infiltration into  soil  itself  is slow, liquids  can rapidly enter bedrock where
soil  is absent, creating sinkholes  and paths for direct flow into groundwater
systems.

                                     17

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     3.    Sites with  little topographic  relief where  groundwater table  is
at or very near the surface (e.g.  old lake beds, floodplains) - high  ground-
water pollution potential.

     4.   Sites with fractured  bedrock  and a  shallow soil  depth (e.g.  in
granitic areas) -  high groundwater pollution potential.

Soil  Characteristics--
     Important soil hydraulic,  physical,  and chemical  properties  that affect
the migration  through the  vadose  zone of hazardous constituents to groundwater
or off-site in runoff  must  also be  characterized.    The  vadose  zone  is  the
region extending from the  ground  surface to the upper surface of the principal
water-bearing  formation  (Everett et  al.  1982).   In this  zone,  water  in  pore
spaces  primarily  coexists with air,  though saturated  regions may  occur.
Perched  water  tables may develop  at  interfaces  of layers with greatly  differ-
ent textures.   Prolonged  infiltration may also result in saturated conditions.
The vadose zone usually consists of  topsoils, which  are weathered geological
materials usually  3 to  6  feet  deep, arranged in more  or  less well-developed
profiles.  Water  movement in  the topsoil  is usually  unsaturated,  with  soil
water at  less-than  atmospheric pressure.    Weathered  topsoil  materials gradu-
ally  merge with  underlying  earth  materials,  which  may  include  residual  or
transported clays  or sands.   The  topsoil differs from the material lying below
it in that  it is  more weathered, contains organic matter and the biological
life  associated with organic matter,  and  is  the zone  of plant-root  growth.
The entire vadose  zone  may  be  hundreds of  feet thick  and  the travel  time  of
pollutants hundreds or thousands of years, while other regions may be under-
lain by shallow potable  aquifers  which  are  especially susceptible to contami-
nation due to  short travel  times and reduced  potential for pollutant  attenu-
ation.

     Those soil  characteristics  that  affect water  movement,  i.e.  infiltra-
tion  and  permeability,  and  those factors  that affect contaminant  mobility
are  the most  important.   It  must  be noted,  however,  that certain waste
characteristics may  affect natural  infiltration  and permeability  of  the
soil  and such   interactions must  be considered (see  section 4).  The site/soil
properties that should  be characterized  are given in  Table  3-2.   If  such  a
complete soil  description  can be  obtained,  predictions  for potential migration
can be fairly  accurately defined.

Soil  Classification--
     There  are three  systems  under  which  soils  are most  likely  to  have
been  classified in  the  United  States  (Fuller  1978):  the Unified Soil  Classi-
fication System (USCS),  the  1938  U. S.  Department of Agriculture System (USDA)
and the present (I960, 1968)  U. S. Department of Agriculture System.

     The  USCS was  developed  to describe   engineering properties  of  soils.
(Fuller  1978).   Classification  of soil  types  are based  on  particle  (grain)
sizes and response to  physical  manipulation  at various  water  contents.   An
abbreviated  description of  the  system (not  including  information on  manipu-
lation  (liquid  limit  and  plasticity  index)) is  given in Table  3-3   (Fuller
1978).
                                      18

-------
TABLE 3-2.  SITE AND SOIL CHARACTERISTICS  IDENTIFIED AS  IMPORTANT  IN  IN  SITU
                                   TREATMENT
Site location/topography and slope

Soil type, and extent

Soil profile properties
     boundary characteristics
     depth
     texture*
     amount and type of coarse fragments
     structure*
     color
     degree of mottling
     bulk density*
     clay content
     type of clay
     cation exchange capacity*
     organic matter content*
     pH*
     Eh*
     aeration status*

Hydraulic properties and conditions
     soil water characteristic curve
     field capacity/permanent wilting point
     water holding capacity*
     permeability* (under saturated and a range of unsaturated conditions)
     infiltration rates*
     depth to impermeable layer or bedrock
     depth to groundwater,* including seasonal variations
     flooding frequency
     runoff potential*

Geological and hydrogeological  factors
     subsurface geological  features
     groundwater flow patterns  and characteristics

Meteorological  and climatological  data
     wind velocity and direction
     temperature
     precipitation
     water budget


*Factors that may be managed to enhance soil  treatment.
                                       19

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 TABLE  3-3.   MAJOR  DIVISIONS, SOIL TYPE SYMBOLS, AND TYPE DESCRIPTIONS  FOR
	THE  UNIFIED SOIL CLASSIFICATION SYSTEM  (USCS)(FULLER  1978) 	
         Major  Divisions
Symbol
Description
Coarse-grained soils
00
r
r
O
CO
CU
01
1
CU
c
r-
U-
co CU
t N
i  00
ro
i- CU
i- >
ra oo
O CM
4- .
 0
ro Z
C
d ra
ra -C
i-
ai cu
i. 01
o s-
00 O)
i NJ
i  CO
t- CU
i. >
CU CU
+J <-
ra 00
O
4- O
O CM
4- .
r O
ro Z
S-
cu ai
0 ^
E
10
to
'cu
ra
S-
CD
CO
C
ro
OO
13
C
ro
oo
00
ro
CO
M
OO
r- CU
4-  
ti"
cu r- J s. >
i- ro  CL> CU
s: c a, t- oo
^ o "> o
C C N
"^ O co O
u -i- z:
0) --^
C i  I  O 00
ro CU +J c CU
CU > !-> C
i  ra -i i- T-
0 S- r 0 4-
tnl^    -
to i
 -c co cu cu - -
cu -*-> cu s- i  oo
> .f c O--Q CD
ra S -i- CL ro C
cu
C (/) i  O -  .
ro T: -t-> c oo
OJ C +J O)
0 00 i 0 -I-
-  4-
oo ^: co cu cu  -
T3 4-> CU S- i  00
C !- SZ Q.J2 CU
ra S > Q- ro C
OO U_ ro -i T-
-  04-
+J C
CO ! 4->
ro co O
i  T3 to LO
O -i- CU
a-1"
i CO
_J T-
r- S_
E CU 0
oo -i +J in
ra cu c
r -a s- ro
_j
Highly Organic Soils
GW
GP
GM
GC
sw
SP
SM
sc
ML
CL
OL
MH
CH
OH
p
Well graded gravels, gravel-sand
mixtures, little or no fines.
Poorly graded gravels or gravel -
sand mixtures, little or no fines.
Silty gravels, gravel -sand-si 1 1
mixture.
Clayey gravels, gravel -sand-clay
mixtures.
Well graded sands, gravelly sands,
little or no fines.
Poorly graded sands or gravelly
sands, little or no fines.
Silty sands, sand-silt mixtures.
Clayey sands, sand-clay mixtures.
Inorganic silts & very fine sands,
silty or clayey fine sands or
clayey silts with slight
_plasticity.
Inorganic clays of low to medium
plasticity, gravelly clays, sandy
clays, silty clays, lean clays.
Organic silts and organic silty
clays of low plasticity.
Inorganic silts, micaceous or
diatomaceous fine sandy or silty
soils, elastic silts.
Inorganic clays of high plasticity
fat clays.
Organic clays of medium to high
plasticity, organic silts.
Peat & other highly organic soils.
 Notes:  ML  includes rock flour.  The No. 4 sieve opening is 4.76 mm
         (0.187  in.);  the No. 200 sieve opening is 0.074 mm (0.0029 in.)
                                    20

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     The USDA system was developed for agricultural  and  other  land  management
uses and  is  based  on  both  chemical  and  physical  properties of  the  soil.   The
first system (1938-1960) was based on soil  genesis,  i.e.,  how  soils formed or
were thought to  have  formed,  while the present system  is based  on quantita-
tively measurable properties of  soils  as they exist in the  field.  The present
system is being constantly refined but is  in general  use by  U.  S. soil  scien-
tists.   The  highest level  of the  present  USDA  system is  described  in  Table
3-4,  and  the approximate  equivalents  in  the  1938 USDA system are  shown  in
Table 3-5.

     Fuller  (1978)  developed  a comparison of  the  USDA  classification  and
the  USCS.   The  part  of the USDA  system  that  can be compared most  directly
in  the  USCS  system is soil texture and associated modifiers  (e.g.  gravelly,
mucky).    The size  ranges  for  the  USDA and the  USCS  particle  designations
are  shown  in Table 3-6.   The two  systems  are  not directly comparable.   The
soil texture designation   in the  USDA system  is  based  only  on  the  amounts
of  sand-silt-and  clay-sized particles in the  soil  (Figure  3-2).   In  the
USCS, the  soil  type is determined  both  on the  amounts of  certain  sizes  of
soil particles and on  the response  of the soil to physical manipulation
at  varying water  contents.  Correlations of USDA  soil  textures and USCS
soil types  are  presented   in Tables 3-7 and 3-8.   Correlations  between USCS
soil types and  other parts of  the USDA system  would  not  be possible.   Texture
is  a major criterion  in  the USCS  but  only a minor criterion  in the USDA
system.    A soil  of a  given texture  can  be classified into  only  a  limited
number of the 15  USCS soil  types.   However, in the USDA system,  soils of  the
same texture may  be found  in  many of  the  10  orders  and 43 suborders of  the
system because of  differences   in their chemical  properties  or  the  climatic
areas in which  they are  located.

     The  complete  USDA  soil  classification system  follows   the pattern   of
(Anderson 1977):

      1.  orders
      2.  suborders
      3.  great  groups
      4.  subgroups
      5.  family
      6.  series
      7.  types

Each level  is  a subdivision  of the  preceding classification  level.   The
orders  are based  on soil   morphology  and  development  similarity.  Suborders
emphasize  genetic  homogeneity.  Great groups are  based on  similarity  in
diagnostic surface and  subsurface horizons.  A  subgroup is based  on  general
similarities  of  profiles of soils located  within  a large  area.   Families  are
based on  properties  important  to  the  growth of plants, such  as texture,
mineral  composition, and soil temperature.   A soil  series is composed  of  soils
with similar but  not  identical profiles   but  with   different  surface  layer
textures.   A  soil  type consists  of soils with similar  surface texture,  and may
be divided into phases based on  some  prominent deviation  (e.g. slope, stoni-
ness, erosion, or  soluble salt content).
                                     21

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         TABLE 3-4.   DESCRIPTIONS OF  SOILS  IN  THE  HIGHEST (MOST GENERAL;
              CATEGORIES OF  THE PRESENT USDA  CLASSIFICATION  SYSTEM
                                (FULLER 1978)
ORDER
DESCRIPTION
Alfisols      Alfisols  have  a clayey subsoil  horizon  and  moderate to  high
              base (cation)  saturation.   Water  is  held  above  the wilting
              point during at least  three of  the warm months  of the year.
              Alfisols  are higher in hydroxy-oxides  (sesquioxides)  than most
              soils, as the  name implies, and therefore may have a  fragipan,
              duripan,  sodium horizon,  petrocalcic (lime),  and  plinthite
              (iron oxides or sesquioxides) or  other  similar  features which
              separate  them  from other  soils.  Where  the  temperature  is
              moderate  to cool,  Alfisols  form a belt  between  the Mollisols
              of the grasslands, and Spodosols  and Inceptisols  of very humid
              climates.  In  warmer climates,  Alfisols form  a  belt between
              Aridisols of arid  regions  and Inceptisols,  Ultisols,  and
              Oxisols of warmer  climates.  Leaching  of  bases  from the soil
              may occur almost every year or  may be  infrequent.

Aridisols     Aridisols occur in arid climates.  They do  not  have water
              available to mesophytic plants  for long periods as do the Alfi-
              sols.  Water is held at less than 15 bars or  it is salty.  A  few
              Aridisols occur in semiarid climates because  they take  up
              water slowly and most  of  the rainfall  runs  off.

              Aridisols have one or  more  pedogenic horizons that may  have
              formed in the  present  dry environment  or  that may be  relics  of a
              former pluvial period. The pedogenic  horizon may be  the result
              of translocation and accumulation of salts, lime,  or  silicate
              clays or  of cementation by  carbonates  or  silica.   The pH usually
              is neutral alkaline, sometimes  highly  alkaline.

Entisols      Entisols  do not have horizon or profile development,  or at least
              no evidence of such.  In  many of  the soils  time has been too
              short for distinct horizons to  differentiate.  Other  Entisols
              are on soil slopes too steep for  water  to pentrate well or where
              erosion rate exceeds development  rate,  still  others are on flood
              or glacial outwash plains which continuously  accumulate new
              alluvium.  Some are wind-moved  sand.  Not all Entisols  are
              young.  Some are actually very  old,  consisting  mostly of quartz
              sand which weathers very  slowly.  Such  materials  as organic
              matter, lime,  gypsum,  iron  oxides,  and  clays  do not accumulate
              or at least only to a  very small  extent.

Histosols     Most Histosols are saturated or nearly saturated  with water most
              of the year.  They are high in  organic  matter and represent what
              is often  described as  mucks, peat bogs, high  moors, or  raised
              peats.
                                     22

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                            TABLE 3-4.   (CONTINUED)
ORDER
DESCRIPTION
Inceptisols   By USDA definition (1968),  in part at least,  "Inceptisols are
              soils of humid regions that have altered horizons which have
              lost bases or iron and aluminum but retain some weatherable
              minerals.  They do not have an illuvial  horizon enriched
              either with silicate clay that contains  aluminum or with an
              amorphous mixture of aluminum and organic matter."  This is a
              difficult soil order to visualize from the description.  It
              represents more what other  soils are not than what they are.
              Inceptisols develop mainly  in the more clayey parent materials,
              in contrast to Spodosols, which develop  in materials which have
              little clay.

Mollisols     Very dark colored soils,  rich in bases and naturally covered by
              grass (steppe land) are called Mollisols.  Many soils of this
              order accumulate lime and/or sodium, and clay.   Mollisols occupy
              extensive subhumid to semi arid areas of  the grass plains in
              the USA.  They are located  generally between  the Aridisols of
              arid climates and the Spodosols or Alfisols of  humid climates.
              These soils are highly productive,  constituting rich crop land
              in the breadbasket areas  of central  and  west  central U.S.
              Areas of Mollisols appear in nearly every state.  Luxuriant,
              perennial grass seems to  be essential  to their  formation.  Where
              waste waters  and leachates  are applied to the surface,  the high
              soil organic  matter plays an important part in  mobility of
              trace and heavy elements.  Where leachate and aqueous wastes
              pass through  subsoils only, 1irne and bases influence mobility
              in addition to the effect of clay minerals.

Oxisols       Those soils which once were called red and yellow laterites are
              now named Oxisols.  Reddish, yellowish,  or grayish soils of
              tropical and  subtropical  climates that form on  mostly gentle
              slopes on surfaces of great age are Oxisols.  They are mix-
              tures of quartz, kaolin,  free oxides and organic matter.  The
              boundaries of horizons blend into each other  so gradually they
              are generally arbitrary.  Weathering has proceeded to great
              depths.   Water moves through these soils rapidly.  Because of
              the high oxide (primarily iron) content  that  coats particles and
              forms granular particulates, these soils attenuate the trace and
              heavy metals  very well.   Oxisols occur in Hawaii.

Spodosols     Two well defined and obvious-to-the-eye  horizons distinguish
              Spodosols.  Just below the  surface layer of forest litter and
              partly decomposed dark organic matter is a bleached layer of
              uncoated quartz sand.   The  second layer, just below, usually
              is coffee color.   Organic matter and iron complexes accumulate
              to give  the dark brown color.   However,  this  spodic is one in
              which amorphous mixtures  of organic matter and  aluminum may also
              occur with or without iron.

                                      23

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                            TABLE  3-4.   (CONTINUED).
ORDER
DESCRIPTION
              Spodosols  generally are  coarse  textured,  containing  only small
              quantities of clay, if  any,  and usually  permit  rapid water
              movement.   These soils  occur under  high  rainfall  conditions  and
              coniferous forest,  though  sometimes hardwoods  are present.
              Attenuation is poor despite  the spodic horizon  where aluminum,
              and often  iron,  complexes  with  organic matter.   Usually the  iron
              and aluminum content is  low, though,  even when  a fragipan (soft
              when wet,  brittle when  dry)  is  present.   The textures are mostly
              sandy,  sandy-skeletal,  coarse loam, loamy-skeletal,  and coarse-
              si Ity.   New England, New York,  Northern  lake states, and Alaska
              are most noted for spodic  (Podzolic)  soils.

Ultisols      The concept of Ultisols  is that of  soils  of  mid-to-low latitudes
              that have  a horizon that contains-an  appreciable amount of
              translocated silicate clay but  few  bases. Highly humid condi-
              tions sometime during the  year  cause  water to move through
              them.  Ultisols  are most commonly found  in warm-humid climates
              that have  a seasonal deficit of rain  and  on  older surfaces.
              They develop from a wide variety of parent materials.  Kaolin,
              gibbsite,  and aluminum-interlaid clays are common in the soil
              clay fraction.  They usually form under  coniferous and hardwood-
              forest  vegetation in the United States.

Vertisols     Vertisols  are clayey soils which crack severely when dry and
              have high  bulk densities between the cracks.  The clay minerals
              are dominated by montmorillonite.  Most  are  found under warm
              climatic conditions, i.e., thermic  or warmer.   In arid regions
              they form in closed depressions or  playas.  Vertisols often  are
              referred to as churning soils because during swelling, pressure
              is exerted, causing them to  heave and recycle the soil.
                                      24

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          TABLE 3-5.  ORDERS IN THE PRESENT USDA SOIL CLASSIFICATION
                SYSTEM AND APPROXIMATE EQUIVALENTS IN THE
                      1938 USDA system (Fuller 1978)
Present Order^
           Approximate Equivalentsb
 1. Entisols

 2. Vertisols

 3. Inceptisols


 4. Aridisols



 5. Mo Hi so Is



 6. Spodosols


 7. Alfisols



 8. Ultisols



 9. Oxisols

10. Histosols
Azonal soils, and some Low-Humic Gley soils

Grumusols

Ando, Sol Brun Acide, some Brown Forest, Low-Humic
Gley, and Humic Gley soils

Desert, Reddish Desert, Sierozem, Solonchak, some
Brown and Reddish Brown soils, and associated
Solonetz

Chestnut, Chernozem, Brunizem (Prairie), Rendzinas,
some Brown, Brown Forest, and associated Solonetz and
Humic Gley soils

Podzols, Brown Podzolic soils, and Groundwater
Podzols

Gray-Brown Podzolic, Gray Wooded soils, Non-calcic
Brown soils, Degraded Chernozem, and associated
Planosols and some Half-bog soils

Red-yellow Podzolic soils, Reddish-brown Lateritic
soils of the U.S., and associated Planosols and
Half-bog soils

Laterite soils, Latosols

Bog soils
aPresent (1960,  1968)  USDA comprehensive soil  classification.

bOld (1938)  USDA soil  classification.

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      TABLE 3-6.  U.S. DEPARTMENT OF AGRICULTURE  (USDA)  AND  UNIFIED SOIL
          CLASSIFICATION SYSTEM  (USCS) PARTICLE SIZES  (FULLER  1978)
USDA
Particle
Cobbles
Gravel
Coarse gravel
Fine gravel
Sand
Very coarse sand
Coarse sand
Medium sand
Fine sand
Very fine sand
Silt
Clay

Size Range (mm)
76.2-254
2.0-76.2
12.7-76.2
2.0-12.7
0.05-2.0
1.0-2.0
0.5-1.0
0.25-0.5
0.1-0.25
0.05-0.1
0.002-0.05
<0.002
USCS
Particle
Cobbles
Gravel
Coarse gravel
Fine gravel
Sand
Very coarse sand
Coarse sand
Medium sand
Fine sand
Very fine sand
Finest
(Silt and clay)

Size Range (mm)
>76.2
4.76-76.2
19.1-76.2
4.76-19.1
0.074-4.76
2.0-4.76
0.42-2.0
0.074-0.42
<0.074
aUSCS silt and clay designations are determined by response  of  the  soil  to
manipulation at various water contents rather than by measurement of  size.
Figure 3-2.  USDA soil textural classification  (Fuller  1978).
                                                           d  Irom
                                                   has  available  ccpy.

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                 TABLE  3-7.   CORRESPONDING  USCS  AND  USDA  SOIL
                       CLASSIFICATIONS  (FULLER 1978)
    Unified  Soil                 Corresponding  United  States
   Classification                Department  of Agriculture
    System (USCS)                 (USDA)  Soil  Textures
     Soil  Types

        1. GW        Same  as  GP--gradation  of gravel sizes not  a  criteria.
        2. GP        Gravel,  very gravelly3 sand less  than 5% by  weight  silt
                    and clay.
        3. GM        Very  gravelly3 sandy  loam, very gravelly3  loamy  sand
                    very  gravelly3 silt  loam,  and  very  gravelly3 loamb.
        4. GC        Very  gravelly clay loam, very  gravelly sandy clay loam,
                    very  gravelly silty  clay loam, very gravelly silty  clay,
                    very  gravelly clayb.
        5. SW        Samegradation  of sand  size not  a  criteria.
        6. SP        Coarse to  fine sand;  gravelly  sandc (less  than 20%  very
                    fine  sand).
        7. SM        Loamy sands  and  sandy  loams (with coarse to  fine sand),
                    very  fine  sand;  gravelly loamy sandc  and gravelly sandy
                    loamc.
        8. SC        Sandy clay loams and  sandy clays  (with coarse to fine
                    sands);  gravelly sandy clay loams and gravelly sandy
                    claysc.
        9. ML        Silt, silt loam, loam  very fine sandy loamd.
       10. CL        Silty clay loam, clay  loam, sandy clays with <50% sandd.
       11. OL        Mucky silt loam, mucky loam, mucky  silty clay loam, mucky
                    clay  loam.
       12. MH        Highly micaceous or  diatomaceous  silts, silt loams  --
                    highly elastic.
       13. CH        Silty clay and clayd.
       14. OH        Mucky silty clay.
       15. PT        Muck  and peats.

aAlso includes cobbly, channery, and shaly.
t>Also includes all  of  textures with  gravelly modifiers  where >l/2 of total
held on No.  200 sieve  is  of  gravel size.
^Gravelly textures  included  if > 1/2 of  total  held on No. 200  sieve
is of gravel  size.
dAlso includes all  of  these  textures with  gravelly modifiers where >l/2 of
the total  soil passes  the No.  200 sieve.
                                      27

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                  TABLE  3-8.   CORRESPONDING  USDA  AND  USCS  SOIL
                      CLASSIFICATIONS  (FULLER  1978)
United States  Department  of  Agriculture
          (USDA)  Soil  Textures
  Corresponding Unified
Soil  Classification System
     (USCS) Soil Types
 1. Gravel,  very gravelly loamy sand

 2. Sand,  coarse sand,  fine  sand

 3. Loamy  gravel,  very  gravelly sandy
    loam,  very gravelly loam

 4. Loamy  sand, gravelly loamy sand,
    very fine sand

 5. Gravelly loam, gravelly  sandy clay
    loam

 6. Sandy  loam, fine sandy loam, loamy
    very fine sand, gravelly sandy loam

 7. Silt loam, very fine sandy clay loam

 8. Loam,  sandy clay loam

 9. Silty  clay loam, clay loam

10. Sandy  clay, gravelly clay loam,
    gravelly clay

11. Very gravelly clay  loam, very gravelly
    sandy  clay loam, very gravelly silty
    clay loam, very gravelly silty clay
    and clay

12. Silty  clay, clay

13. Muck and peat
        GP, GH, GM

        SP, SW


        GM


        SM


        GM, GC


        SM

        ML

        ML, SC

        CL


        SC, GC




        GC

        CH

        PT
                                      28

-------
     Identification of  kinds of  soils at  a  site  in  terms of  the higher
categories  of the  classification  system  can provide information that is
relevant  to identifyinq pollutant  attenuation  and migration.   The names
of soils  from the order  to  subgroup  level  are  composed  of  a  series  of forma-
tive elements, which can be used to  predict  many  soil  properties  relevant to
in situ teatment  of wastes.   Table 3-9 illustrates  the kinds of  information
that can  be  inferred from soil names  using the order Mollisol as  an  example.
The reader  is referred  to  Soil  Taxonomy (Soil  Survey Staff 1975) for a com-
prehensive description of the  USDA soil classification system.

SI ope--
     The  type and  degree  of  slope  indicates surface drainage problems.
Concave slopes cause surface runoff to converge while convex slopes  disperse
runoff (U.S. Environmental Protection Agency 1980).

Soil  Profile Properties--
     In climates  where   there  is  sufficient  rainfall, soils  become highly
organized  into layers (horizons).   A soil profile  is  a vertical  cross-section
of the  soil, made  up of several  horizons,  each  having its  own  distinctive
characteristics.   Descriptions  of  soil profile  characteristics  made in the
field are especially valuable,  because predictions  about waste management can
be made more accurately.

Soil  Horizons--
     Soil  horizons   are  designated  A, B,  and C to  represent the surface
soil,  subsoil,  and  substratum, respectively.   The A and  B horizons are
formed by weathering and other  soil-forming  processes.   The  C  horizon  is
usually the  parent  material  or  undifferentiated geological  deposits  from
which the A and  B horizons  developed  and  is unaltered  by soil  forming pro-
cesses  (e.g. sediment  from  ancient sea  and  lake  beds,  loess  blown  from
dry floodplains, rocks and  rock  powder  released  from  melting  glaciers,
alluvium   from flooding   streams).    Not all  soils have all  three  horizons,
while many soils show variations within each master  horizon.   A hypothetical
soil  profile with all the common soil  horizons is  illustrated in  Figure 3-3.
Each  horizon  can have significantly different characteristics such as depth,
texture,  structure,  bulk  density and  chemical properties which will  result in
differing  drainage and pollutant attenuative characteristics.

Boundary Characteristics--
     Boundary characteristics,  especially  abrupt  changes  in texture and
structure  (e.g.  clay or  sand  layers,  hard pans) can adversely affect  vertical
percolation  of water.  Horizontal  flow may  result from  textural discontinui-
ties,  thus resulting  in contamination of adjacent  areas.

Depth--
     The  depth of the soil  profile is  important for  attenuation of hazardous
constituents moving   through  the  soil  zone,  with  greater  depths  beinq  more
desirable.  K.W. Brown  and  Associates,  Inc.  (1980)  suggest a depth of three
times  the  depth of incorporation of a hazardous  waste  or  1.4 meters, whichever
is greater,  as appropriate  for treatment of hazardous wastes.  Federal regu-
lations  for  the land  treatment of hazardous  wastes  also require 1.4 m  (Federal
Register  1982).   In  general,  the greater the depth  of the soil  profile, the

                                     29

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TABLE 3-9.  INFORMATION THAT CAN BE INFERRED FROM THE USDA SOIL CLASSIFICATION
            SYSTEM, USING THE ORDER MOLLISOL AS AN EXAMPLE.  (FORMA-
             ELEMENTS FOR THE CLASSIFICATION LEVEL ARE UNDERLINED)
               (ADAPTED FROM AGRICULTURAL RESEARCH SERVICE 1974)
Soil Classification     Example
     Level
                 Information Relevant to In Situ
                           Treatment
Order

Suborder
Great Group
Subgroup
Mo11iso 1     Fertile, high in organic matter

Boro11       Long cold, winters; soils frozen for
             extended periods; only short time periods
             that soil is warm enough for biological
             activity

Aquoll       Naturally wet; often develops in low
             places where water collects and stands

Xerol1       Dry for extended periods in summer;
             in most, moisture moves through soil  in
             underlying layers in winter

Calcixeroll  Strong concentration of calcium carbonate
             or gypsum at some depth above 60 inches;
             calcareous in all parts above that depth
             unless texture is sandy

Argixerol1   Horizon of clay  accumulation in subsoil;
             most with horizon of carbonate accumula-
             tion below that

Aquic        Moderately shallow groundwater at some
Argixeroll   times of the year unless artificially
             drained

Lithic       Hard rock at shallow depths
Argixerol1

Vertic       Fine-textured soils with deep, wide
Argixeroll   cracks at some period  in most years

Typic        Lacking features or combination of
Argixeroll   features specified for other subgroups
                                      30

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Corrccsee  of organic matter on
unoio*ed  soils.  Usually aosent from
S31 "3  developed unaer crass
vegetation.
                                                                 iave' in wn;i
                                                         mstts-  is -ecocnizatsie
The cominant  features of A horizcns
are one or more of the following:
(1) an accumulation of organic matter,
formsd at  or  adjacent to tne surface
of tne mineral portion of the soil;
(2) a loss of clay, hydrous oxides of
iron or aluminum, or both, with
resultant  concentration of resistant
minerals of sand or silt size.  7?ie
maximum biological activity in the
mineral portion of the soil occurs
in tne A horizon.
The oominant  features are one or more
of the following:  (1) an accumulation
of silicate clay,  organic matter, or
hyarous oxides  of  iron or aluminum;
(2) a residual  concentration of
sesouioxioes  or silicate clays; (3)
coatings of sesQuioxides to give
conspicuously darks', Stronger, or
redder colors;  (<) an alteration of
material from its  original condition
that OD!iterates original rock
structure, forms silicate clays,
liberates oxides and forms granular,
b'locxv or prismatic structure.
 Underlying consolidated becrock,
 which is not  necessarily the parent
 material.
*


X.
'

I
r
\
1
\
V
f
V.
02
A1
A2
A3
B1
B2
B3
C

R
O-gamc layer in WHICH r*cst slant 0'
animal matter csnnot oe recosmzea.
Characte-ized 5y an accumulafon c-
organic matter mixed wi tn tne mmeral
matter anc coatinc trie mineral
particles, darkening the color of tne
soil mass.
Characterized by loss of clay, iron, or
aluminum, with resultant concentration
of Quartz or othe" resistant minerals
in sano and silt sizes. This horizon
is generally lignte^ in color anc1
lower in content of organic Tatter than
tne AT horizon.
Transitional to E, but rr.ore like A
than B. Sometimes assent.
Transitional to B, but more like 5
than A. Sometimes aosect.
Part of the B horizon in which the "3"
properties are without clesrly expressed
subordinate characteristics indicitinc
that the horizon is transitional to an
adjacent overlyino A or adjacent
underlying C or R.
A zone of transition between S and
C or P..
Nume-ous modified layers recoomisd
by use of cnaractenstic suffixes.


Figure  3-3.   A hypothetical  soil  profile  illustrating the common  soil horizons
                (Otis  1983).   Used  by permission, see  Copyright  Notice.
                                             31

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greater the protection against migration of hazardous constituents to ground-
water and  greater the  soils  attenuation  properties.

Soil  Texture--
     Soil   texture is  a  description of the  particle  size distribution of
various soil  separates (particles  less  than  2 mm).   The  USDA  soil texture
system was  shown  in Figure  3-2,  while a  comparison  of the  USDA system and
USCS system was  shown  in  Table 3-8.  K. W.  Brown  and Associates Inc.  (1980)
described  soil characteristics  important to  hazardous  waste  treatment  based on
soil  texture in the  following manner:

     The  sand and  gravel  particles  are  normally  thought of  as  the
     coarse separates,  and  soils  dominated  by these  coarse separates
     are usually  of an open character,  have low water-holding capacity,
     possess  good drainage,  high  permeability and  aeration,   and   are
     generally in a loose friable  condition.   In  contrast  to the coarse
     separates,  the  silt  and clay  particles  are  considered  the  fine
     separates.   Silt  particles  are  micro-sand particles  predominantly
     composed  of  quartz and have  some plasticity,  cohesion, and  adsorp-
     tion.  A high percentage of silt  is undesirable  and  leads to physi-
     cal problems such as  soil crusting.  Clay  particles are  very small,
     less   than  0.002   mm  in  diameter,  and therefore have  a  very  high
     surface area.  Clays are  commonly flat or plate-like, highly plas-
     tic,  cohesive,  and have  a  very high  adsorptive  capacity for water,
     ions   and  gases.  In  general  soils  high  in  silt and clay are called
     fine   textured soils  and are  very  plastic, cohesive,  high   in water
     holding  capacity, and  have  very slow  water and  air  permeabilities.
     Each  type of soil,  fine  or coarse,  has various advantages  and
     disadvantages for use  in  a  waste disposal  system.   Coarse  textured
     soils will remain oxidized while fine  soils may often  become reduced
     due to wetness.   The oxidation state will  play an  important role in
     how quickly, by  what pathway, and in  what form various waste  con-
     stituents will  be degraded.   Ammonia,  for example, will be rapidly
     converted to nitrate  in  an   oxidized  coarse  soil  and,  due to  the
     potential for rapid  water infiltration, may leach to  the  groundwater
     supply.   Oxidation  also  affects  the  degradation of organics by
     regulating  which  and  how  many microbes  can  exist.   Therefore,  a
     given hydrocarbon will  degrade via one pathway at  a  rapid rate  when
     well   oxidized,  a slower  rate when  less well  oxidized,  and via  a
     second pathway  and   rate  when under  reduced  conditions.   This  is
     exemplified by the data of Gibson and  Yeh (1973)  who  show that  under
     aerobic  conditions the primary pathway for hydrocarbon  degradation
     is  oxidation  to  form  epoxides  while under  anaerobic conditions
     organic  materials are mainly  fermented  into  organic  acids  such
     as methanol.  The  high  adsorptive  capacity  of  the   fine  textured
     soils may, however,  be  very  useful in  holding  various  ions,  such as
     heavy metals,  in  an  immobile form and preventing  their movement to
     water supplies  or other undesirable areas....   In general,  it can be
     suggested  tnat  hazardous  waste  land  treatment  facilities not  be
     established  on extremely  deep sandy  soils  due to  the  potential  for
     leaching  to groundwater.   Similarly,  silt/ soils  having   a  severe
     problem  with crusting  should not be  selected  dje  to the  extreme


                                      32

-------
     potential for runoff.   In  general,  the loam, silt  loam,  clay  loam,
     sandy clay  loam,  silty  clay  loam,  silty clay, and  sandy  clay  soils
     are best suited for land treatment  of hazardous wastes.

     A  summary  of the  advantages  of each  type  of soil  texture  in the  USDA
system  is given in Table 3-10.

Soil Structure--
     Soil  structure  refers  to the aggregation of  primary  soil  particles
(sand,  silt,  and  clay)  into  compound particles or clusters of  primary  parti-
cles, which  are  called  peds.   The aggregates,  separated  by surfaces of weak-
ness or  open  planar  voids,  are  often seen as cracks  in the soil.   The  struc-
tures of the  different  horizons of a soil profile are  essential  characteris-
tics of  the  soil  profile just as  are texture or  chemical composition.  Seven
basic structure types are defined  by the  shape  and arrangement  of  peds.  These
are  illustrated  in Figure  3-4.    Soils  may also have  no  structure:   coarse
textured soils  with  no  texture are called  single  grain while fine textured
soils  are  called  massive  (soil  material  clings  together  in  large uniform
masses).  Aggregate  formation is  thought to result from  the cementing  action
of  soil  colloidal  matter (clay  minerals,  colloidal  oxides of  iron  and manga-
nese,  and  colloidal  organic  matter).   Aggregation  may vary  in  stability,
changing in  response  to moisture  content,  chemical   composition  of the  soil
solution,  biological  activity,  and management practices.    Soils  high  in
shrink/swell  clays  show  particularly dramatic  structural changes in response
to changes  in water content.

     Structure may modify the  influence  of texture  in regard  to moisture
and  air  relationships.   Interpedal  voids  are often large and  continuous  com-
pared to voids  between the primary  particles  within  the peds.   For example,
a soil  with a high content  of plastic clays would  exhibit  limited  permeability
if  it did not have a well-developed  structure which facilitates water and air
movement.   Aggregates  in  coarse  textured soils  stabilize  the  surface  and
increase water retention in the  soil.

     The type  of  structure  determines  the  dominant  direction of  the  pores
and  thus the direction of water movement.  Platy  structures restrict vertical
percolation, prismatic and columnar  enhance vertical  percolation,  and blocky
and granular enhance percolation both vertically  and horizontally  (Otis 1983).
Structural  units  that  can  withstand moderate handling without  disintegrating
will provide better hydraulic properties.

Color--
     Color  and color  patterns  in  soil are  good  indicators  of drainage char-
acteristics  of  soil.    Soil  colors can  be described  in  general  terms  (e.g.
brown,  gray, yellow,  etc.)  or by the  Munsell  color system, which characterizes
a color in  terms  of hue,  value,  and  chroma.

     Uniform  red, yellow,  or brown colors indicate  that  a  soil  is  well-
drained  and  seldomly or never  saturated  with  water.   Gray   or  blue  colors
indicate that  the soil  is  saturated continuously  or  for  extended periods.
Soils with  spots  or streaks  of  red,  yellow,  or black  in a gray matrix ("mot-
tled")  are  usually periodically  saturated with water.


                                      33

-------
          TABLE 3-10.   SUITABILITY OF  VARIOUS  TEXTURED SOILS FOR LAND
           TREATMENT OF HAZARDOUS INDUSTRIAL  WASTES  (K.  W.  BROWN AND
                              ASSOCIATES  1980)
Texture
       Advantages
      Disadvantages
Sand
Loamy sand
Loam
Silt loam
Silt
Silty clay
loam
Silty clay



Clay loam
Clav
Sandy clay


Sandy clay
loam
Very rapid infiltration
Usually oxidized & dry
Low runoff potential
High infiltration
Low to medium runoff
Moderate infiltration
Fair oxidation
Moderate runoff potential
Generally accessible
Good CEC

Moderate infiltration
Fair oxidation
Moderate runoff potential
Generally accessible
Good CEC

Low infiltration
Fair to poor oxidation
Good CEC
Good available water

Medium-low percolation
Fair structure
High CEC

Good to high available
water
Medium-low percolation
Good structure
Med-poor aeration
High CEC
High available water

Low percolation
High CEC
High available water


Med-low percolation
Mea-high CEC

Med-high available water
Good aeration
Very low CEC
Very high hydraulic
conductivity rate
Low available water
Little soil structure

Low CEC
Moderate to high hydraulic
conductivity rate
Low to medium available water

Fair structure
Some crusting
Fair to poor structure
High crusting potential
Poor structure
High runoff


Med-low infiltration
Some crusting potential


Moderate runoff
Often wet
Fair oxidation

Med-low infiltration
Mod-high runoff
Often wet
Low infiltration
Often massive structure
High runoff
Sometimes low aeration

Fair structure
Moderate-high runoff

Medium infiltration
                                      34

-------
              Structure
                Type
Aggregate Description
Diagrammatic
 Aggregate
Common
 Horizon
 Location
            Grangular   Relatively nonporous, small and
                          spheroidal peds; not fined to
                          adjoining aggregates

            Crumb      Relatively porous, small and
                          spheroidal peds; not fined to
                          adjoining aggregates

            Platy        Aggregates are platelike. Plates
                          often overlap and impair
                          permeability
             Biocky       Blocklike peds bounded by
                          other aggregates whose sharp
                          angular faces form the cast for
                          the ped. The aggregates often
                          break into smaller biocky
                          peds

             Subangular   Blocklike peds bounded by
              biocky      other aggregates whose
                          rounded subangular faces
                          form the cast for the ped
                              Co
                                         A horizon
                                          A horizon
                                          A2 horizon
                                            in forest
                                            and
                                            claypan
                                            soils

                                          Bt horizon
                                          Bt horizon
            Prismatic    Columnlike peds without
                          rounded caps. Other prismatic
                          aggregates form the cast for
                          the ped. Some prismatic
                          aggregates break into smaller
                          biocky peds
                                          Bt horizon
            Columnar    Columnlike peds with rounded
                          caps bounded laterally by
                          other columnar aggregates that
                          form the cast for the peds
                                          Bt horizon
Figure 3-4.   Diagrammatic  definition   and  location  of  various   types   of  soil
               structure (Foth  1978).   Used by  permission,  see Copyright Notice.

-------
Mottles--
     Mottles  result  from  chemical  and  biochemical  reactions when  saturated
conditions,  organic matter,  and temperatures above 4C occur  together  in  the
soil.  Bacteria utilizing organic matter deplete  oxygen  present  in  the soil.
Other bacteria  continue  the  organic decomposition  using  oxidized   iron  and
manganese compounds instead  of oxygen in their metabolism.  The insoluble iron
and manganese are reduced  to soluble  forms,  causing the soil  to lose its red,
yellow,  and  brown  color  and turning  it gray.   When the soil  drains,  the
soluble  iron and manganese  are carried  with  the  water to the  larger pores in
the soil.  When they,  contact  air-filled  pores,  they are reoxidized, -Forming
insoluble compounds that accumulate  as  red,  yellow or black  spots  near pore
surfaces.  The  soil  from  which the  compounds were removed remain gray (Otis
1983).

Bulk Density--
     Bulk density  is  the  mass of dry soil  per unit bulk  volume.   As  the
density   of  a soil  increases,  the  volume of  pore space  decreases.    Density
and pore  space  relationships  determine  the  ease  and  amount of  air  and water
stored  in and  moving through  pore spaces.   Of soils with the  same texture,
those with higher  bulk  densities are  more dense -with less pore volume and thus
less permeable.   Good structure and lower bulk densities promote good aeration
and  drainage.   Soil bulk densities  usually  increase with depth due  to less
organic   manner,  less  aggregation,  and  compression  from the  weight  of  the
overlying soil   (K.W.  Brown  and Associates,  Inc.   1980).  Sandy  soils, with
particles lying close together,  exhibit hiqh  bulk densities,  ranging from 1.2
to  1.8  g/cm^.    Finer textured  soils  with usually higher  organic  matter
contents  and more structure have more  pore  space and lower  bulk  densities,
generally ranging  from  1.0 to  1.6 g/cm^  (Brady 1974).

Type and Amount of Soil Colloids--
     Clays and  organic  matterThe colloidal  fraction  of  a soil  is  of primary
importance in  the sorptionand immobilization  of hazardous   organic  and  in-
organic  compounds.  The colloidal  fraction,  composed  of organic and  inorganic
particles with  a  maximum  size  of 0.001  mm,  is  the most chemically   active
portion   of  a soil.   These  particles  are characterized  by   a  large exposed
surface   or interface,  a capacity to  adsorb  and hold  solids,  qases,  ions, and
polar compounds,  and  a tendency  to hasten  or retard chemical  reactions by
catalytic action (Anderson  1977).  Of the mineral,  inorganic portion of  soils,
only the clay particles are  colloidal in size  and  even some clay particles are
too large to be classified  as  colloidal.  However,  recognizing the exceptions,
the  term clay   is  used for  the  inorganic colloidal  portion  of soils.   The
organic  colloidal  fraction  is composed of  amorphous  humus,  derived from
organic  materials during their breakdown  by microoganisms.

     Inorganic  soil colloidsThe formation of  soil inorganic  colloids results
from the weathering of minerals,  which  in  mixtures form the  rocks  of the
earth.   Since oxygen and  silicon make up about  75  percent of the earth's crust
on  a weight basis,  most  minerals  are  primary  or secondary  silicates.   The
average  mineralogical  composition  of igneous  and  sedimentary rocks is shown
in Table 3-11.

     Weathering  is  basically a combination  of destruction arid  synthesis
(Brady 1974).  Both mechanical  factors  (e.g.  strains  from  temperature changes,


                                     36

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        TABLE 3-11.   AVERAGE  MINERALOGICAl COMPOSITION OF IGNEOUS AND
                        SEDIMENTARY  ROCKS (FOTH 1978)
                  Used  by  permission,  see Copyright Notice

Mineral
Constituent
Feldspars
Amphiboles and
pyroxenes
Quartz
Micas
Titanium minerals
Apatite

Clay
Limonite
Carbonates
Other minerals

Origin

Primary

Primary
Primary
Primary
Primary
Primary or
secondary
Secondary
Secondary
Secondary
~
Igneous
Rock,
%
59.5

16.8
12.0
3.8
1.5

0.6
-
-
- -
5.8

Shale,
%
30.0

-
22.3
-
-

-
25.0
5.6
5.7
11.4
Sand-
stone,
%
11.5

a
66.8
a
a

a
6.6
1.8
11.1
2.2
aPresent in small  amounts.
pressures  of freezing water, erosive action  of water,  wind, and  ice and
exfoliation)   and  chemical  processes  (e.g.  hydration  hydrolysis  oxidation,
solution, and carbonation)  act  in  the process of weathering.  Rocks are broken
into  smaller  rocks  and  eventually   into their  individual  minerals,  many of
which  are  primary silicates  (i.e.  silicate minerals  not  altered  chemically
because  of  deposition and  crystallization  from  molten  lava).   At  the   same
time, the rock  fragments and minerals  are  changed  to new secondary minerals
either by minor alterations  or complete chemical  changes.   These changes are
accompanied by  a  continued  decrease  in particle  size,  increase  in specific
surface  area  (area  per unit weight)  and by  the  release of soluble constitu-
ents, most of which  may  be  lost in  drainage.  An  illustration of the weather-
ing  process  is  shown  in Figure 3-5.   The size,  number,  and  surface area of
soil particles from  very  coarse sand to clay  are shown  in Table  3-12.

     The minerals  which are synthesized are  primarily  layer silicate clays and
very  resistant  end  products,  usually  iron  and  aluminum oxides.    Soils are
predominately composed  of  these synthesized  secondary  minerals  and  very
resistant primary  minerals  such as quartz.  The sand and  coarse  silt fractions
of soils are  composed  mainly of quartz and generally quite  inactive chemically
(Figure 3-6).   Primary silicates  such as the feldspars,  amphiboles, and micas
are  present  in  sands  but  decrease  in amount in  silts.   Secondary silicates
dominate the  clay  fraction,  while  oxides of  iron and aluminum are important in
the fine silt  and  coarse  clay fractions. The  silicate  clays are  characteristic
of temperate  regions while  the hydrous oxides are  characteristic of the tropic

                                      37

-------
RO
llGN
SEDIME
V.ETAM
-=-
:KS
EOUS.
NTARY.
ORPHIC)
Decomposition
VERY SLOWLY
	 * WEATHERED MINERALS 	 1
lea.QUWt; mu^ov.l.l Con,,nu1 d,s.nleor.lK>r, RESISTA-.-
(accreas in sue) le g ausn;
SLOWLY 1

_^J MINERALS
 _., !C.OSlTIOn *" ^ ie g . ^il.caieci
EASILY WEATHERED rfcrwall,;ation
	 ^ MINERALS 	 1
otivinc. cdlcitel
RESISTANT
Qecomoosiiion DECAY PR'1^
(cnem-cal re.c.,or>sl '\ ' \ % "" F'.'.*'/^"'''
^^ N. V,
\ \ SOLUBLE
N^ Solunor, N^ MATERIALS
Figure 3-5.   Weathering pathways which take place under moderately acid  condi-
             tions common  in humid  temperature  regions.   (Major paths  of
             weathering are indicated by the heavier arrows,  minor pathways  by
             broken  lines.)   (Brady  1974).   Used  by permission,  see Copyright
             Notice.
     TABLE 3-12.   THE  SIZE, NUMBER, AND SURFACE AREA OF SOIL PARTICLES
                                (FOTH 1978)
                  Used by  permission, see Copyright Notice

Particle type
Very coarse sand
Coarse sand
Medium sand
Fine sand
Very fine sand
Silt
Clay
Diameter
(mm)
2.00-1.00
1.00-0.50
0.50-0.25
0.25-0.10
0.10-0.05
0.05-0.002
below 0.002
Number of
particles/ga
90
720
5,700
46,000
722,000
5,776,000
90,260,853,000
Surface area
(sq cm/g)
11
23
45
91
227
454
8,000,000
^Assumed to have  spherical  shapes, based on maximum diameter of the particle
type.
                                      38

-------
                                              jSecondary silicate!
                              ".:: .-Xv/Xv/XvlvXC- X-'-Xv>\\ 1   minerals    [
                          SAND
                     SILT
                                                   CLAY
Figure 3-6.  General  relationship between particle  size
             present  (Brady 1974).  Used by  permission,
                                       and kinds of minerals
                                       see Copyright Notice.
and semitropics,
silicate clays.
though they  do occur  in  temperate regions  intermixed with
     The layer silicates  have  a planar geometry, very  large  specific surface
areas, and very high residual negative  charge  densities which are neutralized
by a  large external swarm of cations,  thus  resulting in a capacity for strong
adsorption  of  and  catalytic  action  towards   hazardous compounds  (Ahlrichs
1972).

     Two basic sheet-like molecules  make  up the structure  of silicate clays.
A tetrahedral  sheet is  composed  of  series  of tetrahedrons  with  four oxygen
atoms surrounding a central  cation,  which is  usually  silicon (Si+4), but may
be aluminum (Al+o),  in a close-packed arrangement (Figure 3-7).  An octahedral
sheet is composed of a series of octahedrons with six oxygen atoms forming the
corners  around  a large  cation,  which  is usually  Al+3, but  may  be magnesium
(Mg+2) or iron (Fe+2 or Fe+3).   The sheets are formed by the sharing of corner
oxygens  (Figure 3-8).

     The  sheets  may be joined  in  one  of two  ways,  1:1 or  2:1 arrangements.
In  1:1   arrangements,   one tetrahedral  layer  is connected  to  one octahedral
layer by sharing  of  a common  oxygen.   Repeats  of this  1:1 unit  produces
the clay kaolinite.  The  2:1  arrangement  has single tetranedral layers joined
to each  side  of the  octahedral  layer  by sharing  of oxygen  atoms.   This 2:1
unit  produces  the  basic  layer of the  clays  montmorillonite,  chlorite, vermi-
culite,  and micas.  The 1:1 and 2:1 units are  shown  in  Figure 3-9.

     Some 2:1  clays exhibit a  very  high  negative  charge  due to  substitution
of  low   valency  for high valency  cations  within  normally  neutral  crystals.
During  formation,   ions of  similar  radi,  such as  Al+3 for  some  Si+4 in the
tetrahedral layer  and  Mg+2  or Fe+2 for Al+3 or Fe+3 in the octahedral layer,
may be substituted.  The  lower valency of the  substituting cation  results  in  a
residual negative charge,  which must be balanced  by a cation external to the
                                      39

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                      (a)
              O and O Oxygens

                     Silicons
                                                (b)
Mgure  3-7.   (a)  Single silica  tetrahedron.    (b)  Sheet structure  of  silica
             tetrahedrons  arranged  in a hexagonal network  (Foth  1974).   Used
             by permission, see Copyright Notice.
                                        Aluminums, magnesiums, etc.
 igure  3-8.   (a)  Single octahedral  unit.   (b) Sheet  structure  of octahedral
             units  (Foth 1974).  Used by permission , see Copyright Notice.
 :1 unit either  on  its edge or  in  the interlayer surface.   Cation exchange
 opacity is an  expression  of  the number of  cation  adsorption  sites per unit
 eight  of  soil.  It  is  defined  as  the sum  total  of exchangeable  cations
 isorbed,  expressed  in  mi 11iequivalents  per 100 grams of oven dry soil.
                        of  silicate clays but  most  are variations  of  a few
                        is the most common 1:1  type  clay.   The 1:1 units are
jnded  together  by  hydrogen  bonding  between  hydroxyl  groups.   There  is  no
iterlayer  surface  area  and  kaolinite  aces  not  swell  with the  addition  of
     There are  a  number
 ijor types.   Kaolinite
        here  is  also  little substitution within the tetrahedral or
;yers  so  the  charge  deficit
id  sorptive capacity.
                            is low.  Thus kaolinite has quite low
                                                                   octahedral
                                                                   reactivity
     Montmoril lonite is  a common 2:1 type clay which has  a negative charge of
 ) to  120  mill iequivalents  per 100  grams  of  soil  and  swells  and shrinks as
 .ter moves freely  between  the weakly bonded 2:1  units.   Water  is attracted
   the  oxygen  surface  of the  clay and  to  the neutralizing  cations  in the
                                      4C

-------
                          7.2 A
                                                   AU
                    c-Axis
                                               a %
                                    b-Axis 
                                   nH20
                                       x+y M
                            Water
                              +
                         Exchangeable
                           Cations

                         (0)6
               2:1
9.6 A
                    c-
                                                    (O).(OH^
                                   b-Axis-
Figure 3-9.   Sketch  showing  an  edge view of the crystal structure of a 1:1 and
             a 2:1 type  clay mineral  (Ahlrichs 1972).  Used by permission, see
             Copyright Notice.
interlayers.   The swelling caused by the water exposes the large surface area
and the large charge  deficit  of  montmorillonite.

     Illite or hydrous mica possesses the same 2:1 structure as montmorillon-
ite but differs  in that  adjacent  2:1 units are tightly bonded by a potassium
bridge.  Illite  therefore does  not  swell  in  water,  and most  of its charge is
neutralized by potassium.  II lite  is expected  to exhibit minimal interaction
with hazardous organic compounds  added to the soil (Ahlrichs 1972).

     Vermiculite  is  similar to  illite, except  that  potassium  is not present,
and the charge deficit is somewhat lower in the crystal.  Vermiculite usually
has hydrated Mg+2 or calcium  (Ca+2) in  the  interlayers  neutralizing the
charge.   A summary  of  the  overall  characteristics of these common  clay
minerals is given in  Table 3-13.

     The hydrous  oxide clays  are oxides containing associated water molecules.
They are formed by intense weathering, where  silicon has  been removed from the
silicate clays,  leaving  iron and  aluminum hydroxides in a  highly colloidal
                                     41

-------
  2LE 3-13.   SUMMARY OF CHARACTERISTICS OF SOUL  COLLOIDS (COOK AND PACE 1973)
                  Used by  permission, see Copyright Notice
                   '.si a  Tit.
            !', lorn te  Irvsta'line.  None
                   ciate like
                                                                     ""-KIL   ;i'_ c  ,
                                                                            DC'1'- .
                                                                            arainee
 --tially- Verrciculite     Crystalline,  Mg(hjG)6   ..      lio      A! - s,     L0(>   ^          M
 cancing             platelike                           tetra'ieoral)      i,:,-;nerr u^
                                                                CandGd
        Illite        Crystalline,  k.      0.1-2.0    15-40    A1 - Si     Lo   Lo.
                   Dlatelike                          I tetranetfral!      T^f
                                                                Canada


 orous  A12CJ3 > M?Q    (OTr,rr>ious    N.A.   colloidal  nh- ae-   H        N.A.   Hion         Fe Ai
 '.aes   Fe?03  H2    Crystal line                pendent   Dissociation      Southeast C.S.,  contain-
                                                                "roPlCi     '  inc
                                                                            "i np^a 15


                   worDtioui.   N.A.    coiloioal  ph-     -CGOf-      LO     o* ', vine      Pijr-
                   UrQan'c                   oep't     -u-      .can   ooorl'v oramec  , smr.ai
                   structure                  (t'OO-M  /P)        lose   area;"

                                                          Dy burn-
-ate.   Their important  sites  for adsorption  are  -OH and  -OH2 on  the outer
-rfaces,  which  may become  charged in  the presence  of excess H+  or OH- ions.
~^e  pH values at  which  the  charge on  the ions  changes  ranges  from  7.5 to  9
-  the  iron  and  aluminum  oxides.    Below  these  values,  the  compounds   are
:3itively charged, thus  providing adsorption capacity for anions.

     The  surface  geometry  of the  silicate clays  is  important in  the attenua-
?n  of hazardous  compounds.   The interlayer  surfaces  provide most of their
^sorptive surface  area  (Ahlrichs  1972).  The  source of  the charge deficit in
  clay  has  been  suggested  as  important  in  determining  the  bonding   action
itween  layers  and consequently the amount of  swelling. Marshall  (1964)
-ggests   that  tetrahedral  sources  of  charge  deficit   give  greater  bonding
-orgies  than  octahedral   sources since  the distance  from the cause of  charge
3,-iciency is closer to the planar surface in the tetrahedra.

     The   size of  the  crystal  c-axis  spacing  (see Figure 3-9) may  determine
 ch compounds  enter the interlayer  of  a clay.   For example, montmoril lon-
 "=   will  allow  almost  any  size molecule or  compound  to  enter   if  there  is
   attraction for  it.   When neutralized with  sodium  (Na+) or  other  similar
ovalent ions  as the exchangeable cations, these  clays are especially  free
 tiling.   Less  swelling  is exhibited  with  multivalent  ions.   The  interlayer
 .-faces  of  vermiculite,  with a more restrained swelling potential then
 :-*morillonite,  are small enough  to prevent  the entrance of many compounds.


                                        42

-------
     The importance of the  spatial  geometry of negative charge  sites in
clays was demonstrated  by Weed and Weber (1968), using two divalent cationic
organic compounds,.   The average distance  between charge sites  in  a montmoril-
lonite is 11-12 A,  while in  micas  it  is 6-8 A.   Diquat, with charge  sites 3-4
A apart  on  ring  nitrogen  groups,  preferentially sorbed  to the higher charge
density (closer spacing) of the micas.-  In paraquat,  the charge sites were 7-8
A apart on  the  ring  nitrogen groups, and paraquat was sorbed preferentially by
montmorillonite,  with its  lower charge density.

     Anion   exchange  on colloidal   clay minerals also occurs  but apparently
to a  much  lesser extent  in most  soils than that of cation exchange.  Anions
may replace the  hydroxyl  groups  in the clays,   and  as these  groups  are more
numerous in kaolinte than  in  other silicate clays, kaolinite is considered to
be primarily responsible  for anion  exchange  in temperature  or  arid  region
soils.   Aluminum and iron oxides  become  protonated  in the acid  environments
which are normal  for highly  weathered  tropical  soils and  thus  are also impor-
tant  in anion exchange  reactions,  as discussed previously.

     Organic colloids--Soil contains many organic compounds in  various stages
of decomposition.Soil  organic matter is  derived  from:   1)   plant material;
2) animal matter; 3) microorganisms,  both living and dead; 4)  synthesized and
secreted products of living  plants and microorganisms;  and 5) decomposition
products of organic  debris (Anderson 1977).

     Schnitzer  (1978)  estimated  that  65  to 75  percent  of the  organic matter
in mineral   soils consists of  humic materials,  i.e., humic acid  (HA),  fulvic
acid  (FA),  and  humin.   They are  amorphous,  dark-colored,  hydrophilic, acidic,
partly aromatic, chemically complex  organic  substances  ranging  in molecular
weight  from hundreds  to  several   thousand, with very  large  surface  areas
(500  -  800 m2/g) and  high  cation exchange capacities.  The remainder of
the  organic matter  is composed   primarily of  polysaccharides  and  protein-
like   substances  (Flaig et al. 1975).    These  include  substances with  still
recognizable physical  and chemical characteristics,  such  as   carbohydrates,
proteins,  peptides, amino  acids, fats, waxes, alkanes and  low molecular
weight  organic  acids  (Schnitzer  1982).   They are readily decomposed by
microorganisms and have  a  short  lifetime in the  soil.  Schnitzer  (1982)
identified  the  following  important characteristics  of all  humic materials:

     1.  Ability  to  form water-soluble  and water-insoluble  complexes  with
         metal  ions  and hydrous oxides.

     2.  Ability  to  interact  with minerals  and a  wide  variety of organic
         compounds,  including alkanes, fatty acids, dialkyl  phthalates,
         pesticides,  herbicides,   carbohydrates,  amino  acids,  peptides,  and
         proteins.

The formation  of water  soluble complex of  FA with metals and  toxic organics
can  increase  the concentrations  of  these constituents in  soil solutions
and natural waters  to levels  much  greater than  their calculated solubilities.
The oxygen-containing functional groups  are  important for  the reactions
of humic materials with metals, minerals,  and organic compounds.   Humic matter
is somewhat  organophilic,  which   is  very  important  for   adsorption  of  some

                                     43

-------
hazardous nonionic organic  molecules.   A summary of  types  of  functional  groups
and distribution  in  humic  materials is  presented  in  Table 3-13a.  The  func-
tional  groups contribute to  a high cation  exchange capacity (200-400  milli-
equivalents/100  g),  thus acting similarly to clays  in preventing  cations  from
leaching.  A summary  of characteristics of soil humus  is  previously  included
in Table  3-6.

     Humus increases  the  water holding  capacity of  a  soil,  since it  swells
when wet  and  can adsorb two to six  times its  own weight  in  water.   However,  it
does rewet slowly if thoroughly dried.

     Humus and  other  organic matter,  because  of their chemical  composition,
can add to the  nutrient status of the  soil,  thus increasing microbial  activity
which  may be  responsible  for  attenuation  of  hazardous  soil   contaminants.
Nitrogen, phosphorus, and  some of  the  minor nutrients,  such  as  sulfur,  zinc,
and boron all  can be contributed by organic  matter.

     The   amount  of nitrogen  in  decomposing  organic  matter  relative to the
amount of carbon  is especially important, for  insufficient nitrogen may limit
the rate  of degradation.   Organic matter with  a low nitrogen  content  (or  wide
C:N ratio) is often  associated  with a slow rate of decomposition.  Materials
which  contain more than  1.5 to 1.7   percent  nitrogen  probably  do   not  need
additional fertilizer  or  soil  nitrogen to  meet the requirements of  micro-
organisms during decomposition.   This  corresponds to a threshold  carbon:nitro-
gen ratio of 25  to  30 (Taylor et al.  1980).   However,  carbon:nitrogen  ratios
should be used with caution, for the ratio does not indicate  the availability
of the carbon or nitrogen to  microorganisms.

     In  summary,  humified  soil  organic matter,  because  of its  surface  area,
surface  properties, and  functional  groups,  can serve  as a buffer, an ion ex-
changer,  a surfactant, a chelating  agent, and  a general  sorbent,  all  of which
are  important  in the  attenuation  of   hazardous  compounds  in soils  (Ahlrichs
1972).
        TABLE 3-13a.   OXYGEN-CONTAINING FUNCTIONAL GROUPS IN HUMIC SUB-
                           STANCES (SCHNITZER 1975).
                                         meq/g
Type of
Material
HA
Humi n
FA

C02H
4.4
3.1
8.1
Phenolic
OH
3.3
2.2
3.9
Alcohol ic
OH
1.9
N.D.a
4.0
Ketonic
C=0
1.2
3.1
1.4
Quinonoid
C=0
1.0
2.0
0.6

Methoxyl
0.3
0.4
0.4
aN.D. = not determined.
                                      44

-------
     Soil pH--Soil  pH  determines  in  part  the  degree  of  surface  charge  on
colloidal-sized soil  particles.   At  high  pH values, negatively charged  sur-
faces develop,  while  at low  pH  values, positively charged surfaces  occur.   The
tendency  for  adsorption of  anions  or cations  is  thus dependent  on  the  pH
of the soil water in  the vadose zone.

     Soil  pH  also has  major  effects on  biological  activity  in  the soil.
Some  organisms  have  small  tolerances  to  variations in  pH  while  others  can
tolerate a wide pH  range.   The  optimum  pH range  for rapid decomposition
of most wastes  and  residues  is  6.5 to  8.5.  Bacteria and actinomycetes
have  pH optima  near neutrality   and  do  not  compete  effectively  with  fungi
under  acidic conditions (Taylor et  al.  1980).  Soil  pH also affects  the
availability of nutrients, as shown in Figure 3-10.

     There are  several  sources of hydrogen  (H+)  and  hydroxyl  (OH-)   ions  in
soil  solutions.  The hydrolysis  of  exchangeable bases  (Ca+2, Mg+2, Na+,  and
K+)  which dissociate  from  cation exchange surfaces  contribute  OH- ions.
Exchangeable hydrogen (H+) which  has  dissociated contributes  H+. Exchangeable
H+ is the  principal  source  of  H+  until the pH of the soil goes below  6,  when
aluminum in the octahedral sheet  of  clays  becomes  unstable  and  is  adsorbed as
exchangeable Al.  Upon hydrolysis, each Al  ion becomes  the  source of three H+
ions.

     The  pH  of  a  calcareous  (containing  CaC03)  soil  or  a  calcareous  soil
horizon  ranges  from  7  to a maximum  of 8.3.   A calcareous  soil  horizon  may
greatly affect  migration of  hazardous compounds by an abrupt change  in  soil  pH
which may affect solubility  or  ionization  states of  the  compounds.

     A  soil high  in  sodium  (sodic soil)  has an even  higher  pH  than  a  cal-
careous soil, due to  the hydrolysis of sodium carbonate  and  the formation  of a
strong  base,  sodium hydroxide.   When the  cation  exchange capacity is  15
percent  or  more saturated  with  sodium,  or  a  significant amount  of   sodium
carbonate exists in the  soil, the pH values range from 8.5 to  10.

     Saline soils are high in soluble salts.   Plant  growth may be impaired  due
to the osmotic  pressure  of the  soil solution  restricting water uptake.  Saline
soils  tend to  have  a  pH at or near  7 due  to hydrolysis  of soluble salts
(Foth  1978).   The pH  of soils can be adjusted by several  means.   Sulfur
compounds can be used  to lower pH or  liming  compounds  can  be  used to raise
pH.

     Oxidation-reduction  potential--In conjunction with  measurement of pH  in
the soil solution, a  measurement of the oxidation-reduction potential or Eh  of
the soil solution will  add  valuable  information.  Eh is an expression of  the
electron density of  a system.   As  a  system becomes reduced, there  is a corre-
sponding increase in  electron density,  resulting  in  a progressively increased
negative potential (Taylor et al.  1980).  With Eh and pH  known, Eh-pH diagrams
can be  constructed  showing  stability  fields  for major  dissolved  species  and
solid phases.    These diagrams  can  be  useful  in understanding the occurrence
and mobility of  hazardous compounds in soils  (Everett et  al. 1982).

     The  maximum  rate  of  decomposition   of  degradable  hazardous  compounds
is correlated  with  a  continuous supply  of  oxygen.    Excessive  levels of


                                     45

-------
Figure 3-10.
 Relationships  in mineral soils between  pH  and  the activity of
microorganisms  and  the  availability of  plant  nutrients (Brady
1974).  Used by permission,  see  Copyright Notice.
degradable  materials  may lead to  depletion of  03 in soil  and anaerobio-
sis, which  slows  the rate and  extent  of  decomposition and may  produce  some
reduced compounds which  are  odorous and  toxic  to microgranisms  and  plants.
Table  3-14  shows  the succession of  microbial  events relative to  soil  redox
potential.

     The degradative  pathways  for  some  hazardous compound may  involve  some
critically reductive steps.   An important  initial  step  in  the degradation of
DDT  is  a reductive  one,  which  requires  anaerobiosis  (Guenzi  and  Beard 1967).
Farr and Smith (1973, 1976)  have shown  that toxaphene and trifluralin degrade
more rapidly under anaerobic  conditions.   Thus an engineering management  tool
to  maximize detoxification and degradation of  some compounds may be  tne
alternation  of  aerobic/anaerobic  conditions  (Guentner 1975)  by  adjusting Eh
                                     46

-------
                    TABLE 3-14.  SUCCESSION OF  EVENTS  RELATED  TO  THE  REDOX POTENTIAL WHICH
                       CAN OCCUR IN WATERLOGGED SOILS,  OR  POORLY  DRAINED SOILS .RECEIVING
                        EXCESSIVE LOADINGS OF ORGANIC  CHEMICAL WASTES OR CROP RESIDUES
                                           (TAKAI  AND  KAMURA  1966)
                                  Used  by  permission,   see   Copyright  Notice
.=
-J
Period
of
Incubation

Early



Later



State
of
Reduction

First
Stage


Second
Stage


System



Disappearance of 02
Disappearance of N03-
Formation of Mn2+
Formation of Fe2+
Formation of $2-

Formation of H
Formation of CH4
Redox
Potential
(Millivolts)

+600 to +400
+500 to +300
+400 to +200
+300 to +100
0 to -150

-150 to -220
-150 to -220
Nature
of
Microbial
Metabolism
Aerobes
Facultative
anaerobes

Obligate
anaerobes


Formation
of
Organic
Acids
None
Some accumulation
after addition of
organic matter
Rapid accumula-
tion
Rapid decrease


-------
through flooding or  cultivation.   Anaerobic conditions may  be  maintained by
keeping the soil saturated with water  and  limiting aeration.  Regular culti-
vation of soil  can  be used  to maintain  aerobic conditions.

     Nutrient  statusThe biological  degradation  of hazardous compounds
requires the presence of  nutrients  for  optimum biological growth (Table 3-15).
Three  of  the major  nutrients,  nitrogen,   phosphorus,  and  potassium,  can be
supplied,in common inorganic fertilizers.   Calcium deficiencies usually occur
only in acid soils  and can be  corrected by liming.  If the soil is deficient
in magnesium,  the use of  dolomitic  lime is  advised.  A high level of exchange-
able bases  (calcium,  magnesium,  sodium, and  potassium) on the surface exchange
sites of the soil  is also desirable for good microbial activity and to prevent
excessively acid conditions.

     Though sulfur  levels  in  soils  are  usually  sufficient, sulfur  is   also
added  as a constituent  of most  inorganic  fertilizers.   Micronutrients   also
occur  in  adequate  amounts in most  soils.  At  hazardous  waste sites,  the
primary danger  may  be in overloading of the soil  with  one  of  these elements
 TABLE 3-15.   ESSENTIAL  ELEMENTS  FOR  BIOLOGICAL GROWTH (BASED ON REQUIREMENTS
                    FOR  PLANT  GROWTH)  (TISDALE AND NELSON 1975)
                     Used  by permission,  see Copyright Notice
    Elements
Minor nutrients:
Iron
Manganese
Boron
Molybdenum
Copper
Zinc
Chlorine
Sodium
Cobalt
Vanadium
Silicon
                                     Source
Major nutrients: Carbon "^
Hydrogen >
Oxygen )
Nitrogen "^
PhosphorusV
Potassium f
Sulfur J
Calcium >
Maqnesium J

Air
and
Water
Soil, inorganic
fertil izers,
or in waste

Soil liming
materials, or in
waste
                                                       Soil, soil
                                                       amendments,
                                                       in waste
or
                                      43

-------
which may have been in the waste,  thus causing toxicity  and  leaching  problems.
The  pH  of the soil  is also  important,  for it determines for  some of the
elements  their solubilities and availabilities  and thus  toxicity  and  leaching
potential (Figure 3-10) (K. W. Brown and Associates  1980).

Hydraulic Properties of the Soil  Profile--
     Soil/water relationships and associated  soil hydraulic  properties  affect
both the  movement  of hazardous compounds  through the  soil  and the soil  pro-
cesses  acting  within  the  soil  profile  to effect  attenuation  of waste  com-
pounds.   Biodegradation of waste  chemicals requires  water for microbial  growth
and  for  diffusion  of  nutrients  and  by-products during the breakdown  process.
Soil hydraulic properties  are those properties  whose measurement  involves the
flow or retention of water within  the  soil profile (U.S.  EPA  1977).

     The total volume of a soil consists of about  50  percent  pore  space  and  50
percent  solid  matter.   Water  entering  the soil fills  the  pore  spaces  until
they are  all  full.  The water then continues to  move  down   into  the  subsoil,
displacing  air  as  it  travels;  this  flow, when  the soil is  at  its maximum
retentive capacity,  is  said to be  saturated.   After water  input  to  the  soil
ceases,   the  water  drains  from the  pores,  and  the  soil  becomes  unsaturated.
Water in  the  soil  below the saturation level is held in the soil against the
force of  gravity.  The  forces that  hold  the water in the soil  result  from the
surface tension of  water, the  cohesion of water  molecules, the  adhesion
of water molecules  to soil  surfaces,  and other electrical  forces at the
molecular level.   The terms soil  water  pressure potential or matric potential
are  used  to  describe  the  energy  required to  remove water from an unsaturated
soil.  This  energy may be expressed  as a potential,  (e.g., erg/g), as  pressure
(e.g.,  dyne/cm2 or bar),  or as pressure head (e.g., cm).  All  of these  terms
are  negative  quantities,  since water  is  held  in the soil  pores  at less  than
atmospheric  pressure.  Soil tension and suction are  also  used  to  describe the
energy of soil water retention,  but  are  reported  as positive  quantities and
are not precise in  regard to units.

     The  force by which  water  is  held  in  the soil pores  is approximately
inversely proportional to  the pore  diameter.   As  water  evaporates or drains,
the  larger,  or macropores, drain  first, while the smaller, or  micropores, are
still filled  with  water.   Therefore,  as soil water  content  decreases, the
absolute value of the matric potential  increases.   A graphical  representation
of such  a relationship is  known as  a soil  moisture characteristic  curve  and  is
illustrated  in Figure 3-11 for several different soil textures.   The  shape  of
the soil water characteristic curve is strongly dependent on soil texture and
structure.  Soils  witn  primarily  large  pores", such  as sands,  lose nearly all
their water  at a  very small (absolute  value)  matric potential.  However,  soils
with a mixture of pore  sizes, such  as loamy  soils, hold  more water at satura-
tion due  to a greater  porosity  and  lose water more slowly as  the  absolute
value of the matric potential  increases.

     The  terms  field  capacity  and permanent wilting  point are  qualitative
descriptions of  soil  water content.   Field  capacity refers to  the  percent-
age  of water  remaining  in a soil after  having  been  saturated  and after free
gravitational  drainage  has  ceased.  Gravitational water movement  is  signifi-
cant in  migration due to leaching of hazardous compounds  ana  nutrients for use

                                      49

-------
                            SOIL WATER CONTENT 9m

                        (MASS OF WATER/MASS  OF DRY SOIL)
                               01
                                           02
                                                       0 3
                                                         F 1 ( LO C ' C I TT

                                                           (0.3 03')

                - I 600
Figure 3-11.   Soil-water  characteristic curves for  several  soils  (Taylor  and
              Ashcroft  1972).   Used  by  permission, see Copyright Notice.
in microbial  degradation  of the  compounds.    Also,  if water  does  not drain
quickly from the soil, it may have a harmful effect on microbial activity due
to poor  aeration.   It  may also  affect solubility of  compounds  due to an
alteration in oxidation-reduction potential.   Field  capacity of a  particular
soil   is  not   a  unique value but  represents  a  range  of  water  contents.   In
sands, moisture content  at field capacity corresponds to matric potentials in
the range of  -0.10 to -0.15 bar, while  in medium  to fine-textured,  potentials
range from -0.3 to -0.5  bar,  with  -0.3  bar most commonly  used.

     Drainage does  not  cease  at  field  capacity  but continues  at  a  reduced
rate  aue  to  movement of  water  through  micropores by  capillarity.   Adhesive
attraction between  the  water  and  the  walls  of  the micropores  causes water
to move  through the  pores,  pulling  along  other  water  due  to  the cohesive
attraction between water molecules.   Capillary  water can  move in  any direction
in the soil,  following micropore channels.

     When moisture  in  a  soil   is  no longer  in  adequate  supply  to meet the
demands of plants growing in the soil,  ana plants wilt and remain wilted, the
moisture content is said to be  at the  permanent wilting  point.   This moisture
content occurs  in most soils when the matric potential is  in the  range of -15
bars.   The  amount  of water held  in a  soil  between field  capacity   arid the
permanent wilting  point is known  as  available  water.  This  is  the water
available for plants  and for soil microbial and chemical reactions.   Informa-
tion  on  optimal and marginal water  potentials  for growth,  reproduction, and
                                      50

-------
survival of  individual  species  of  microorganisms  in soils  is  limited  (Taylor
et al .  1980).  Bacterial activity is highest in wet  conditions,  but noticeably
decreases by about  -3  bars  (Clark  1967).  Some fungi can  grow  and survive  in
soils  under  dry  conditions.   Fungal  growth  is often decreased  in  wet  soils,
suggesting that bacteria may be  antagonistic to fungi under these  conditions.
At low potentials,  bacteria are  less active,  thus  allowing fungal growth (Cook
and Papendick 1970).

     As  seen  in  Figure 3-12,  though  fine-textured  soils  have the  maximum
total water-holding capacity,  medium textured soils  have the maximum available
water due to favorable  pore size distribution.  Even  at the permanent  wilting
point,  soil  contains a  considerable  amount of  water,  though it  is  unavailable
for use.  This water, which is  bound tightly to individual soil  particles,  is
known as hygroscopic water.

     Permeability  describes  the  ease  with  which  liquids  pass through  the
soil.  Knowledge of permeability is  necessary  to  predict  the rate  of movement
of hazardous compounds  through a soil profile.

     Water moves through soils according to Darcy's  Law:

     q   =  K  dH/dL                            "                          (3-1)



     q      =  flux  of water per  unit cross sectional area (cm/h)

     K      =  permeability of  hydraulic conductivity (cm/h)

     dH/dL =  total head (or hydraulic) gradient (m/m)

The total head  is the sum of the soil water pressure head (h) and the head due
to gravity (z),  or H =  h + z.  The  path length  of  water  is L.

     The hydraulic conductivity constant K is  not a true  constant  but  changes
rapidly  as  a function  of  water content.   Even  under conditions  of  constant
water content,  K  may change due to  swelling  of clay particles  or  changes  in
the chemical nature of the  soil  water.   Due to  their negatively charged
where
                         Sand  Sandy Loam
                             loam
                                          Clay
                                          loam
Clay
Figure 3-12.   Typical  water-holding  capacities  of  different  textured  soils
              (Fcth 1978).   Used  by permission,  see Copyright  Notice.


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nature,  soil  clay  particles  tend to  repel  each other  and  remain  dispersed,
resulting  in low permeability.    Positively charged  cations  in  the  soil  water
neutralize the negative  charges  and  allow the  soil particles to  come  close
enough together so  that  floccul ation can occur, which increases soil pore size
and permeability.  Thus  a water low in salts  may result  in permeability
problems.

     However,   sodium  in  its  hydrated state  is  much  larger  than   the  other
common cations  and tends  to  keep clay  particles  dispersed.    If  sufficient
salt  is  present,  the  layer  of   sodium  ions  will be  suppressed  so  the  clay
particles can flocculate.  However, the required salt concentration  may
be  so  high  as  to  restrict microbial  activity  and  degradative  processes  in
the soil.   The  sodium  adsorption ratio  (SAR)   is  used  as  a  measurement  of
the degree  to which  sodium will be  adsorbed  by  soils from  a solution  in
equilibrium with  the soil.  Specifically:


    SAR =       a
          Ca * + MgV2


where the ionic  concentrations are expressed in mi lliequivalents per liter.

     As  a general  rule,  an  SAR  of 15  or  greater is considered unacceptable.
However,  there  is  a difference depending  on  the  dominant  clay type.   With
kaolinate,  the  SAR may  be  as high  as 20  before   serious  swelling  problems
occur.   However, with  soils  in which  montmoril lonite  is dominant,  SAR values
of 8-10 may  cause  serious swelling problems  (Ferguson 1976).

     Other  chemicals, especially organic compounds, may  also alter  soil
permeability.   Potential  for such alteration  should be  investigated  in order
to predict and minimize  leaching of the  compound,  if  it is hazardous itself,
or to determine if  it would increase  the leaching of  associated  hazardous
compounds.

     Soil permeability is primarily determined by  soil  texture,  with coarser
materials usually  having  higher conductivities.  However,  soil  structure may
also  be  important  by  increasing macropore  space  in a  finer-textured  soil.   A
listing  of  permeability  values for  soils  classified by the  USCS  is  shown  in
Table 3-16.

     Hydraulic   conductivity  decreases  greatly  as water  content  decreases
below  saturation.    In sandy soils,  though  permeability  is much higher  at
saturation than  in loamy soils,  permeability  decreases more  rapidly  as the
matric potential  becomes more  negative,   eventually  becoming  lower  than  in
medium textured  soils.

     Drainability  is a term used  to describe the relative rapidity and extent
of removal of water  from a  soil  profile.   Drair.ability is dependent  upon the
permeability (i.e.,  K, the  hydraulic  conductivity) and groundwater relation-
ships that  are  controlled by  soil  properties  and the  position  of the site on
the lancscape (i.e., the  hydraulic gradient, dH/dL). A well-drained soil  (e.g.
a  loamy  soil)  is  one  in which  water  is  removed readily but  not  rapidly;  a


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         TABLE 3-16.  PERMEABILITY  VALUES  FOR  SOILS  CLASSIFIED  IN  THE
           UNIFIED SOIL CLASSIFICATION  SYSTEM  (YANG  AND  BYE  1979)


Earth Material Category           Unified  Soil               Permeability
                                 Classification            Range (cm/sec)
                               System Designation


Gravel                              GW,  GP
Medium to Coarse Sand               SW,  SP              Permeable
Fine to Very Fine Sand              SW,  SP              >10-4 cm/sec

Sand with <15% Clay, Silt           GM,  SM,  SC           Semi-permeable
Sand with >15% but 50% Clay        GM,  SM,  ML           10-2 to 10-6 cm/sec

Clay with <50% Sand                 OL,  MH              Relatively impermeable
Clay                                CL,  CH,  OH           <10-6 cm/sec
poorly drained soil (e.g., a poorly structured fine soil) remains waterlogged
for extended  periods  of  time,  resulting  in  reducing  conditions  and  insuffi-
cient  oxygen  for  biological  activity;  an  excessively  drained  soil  (e.g.  a
sandy  soil)  is  one  in which  water  is removed  so completely  that  droughty
conditions occur.

     For  in  situ treatment of  hazardous  waste contaminated  soils,  the most
desirable soil  would  be one  in  which  permeability was  only  large  enough to
maximize soil attenuation processes  (e.g.  adequate  aeration for  aerobic
microbial degradation) while  still  minimizing  leaching  (assume  lower perme-
abilities protect against  leaching).

     Infiltration rate refers  to the rate at which water enters  the soil from
the surface.  When the  soil  profile  is saturated, the  infiltration rate
is  equal  to the  saturated hydraulic  conductivity.   However, when  the soil
initially is relatively dry, the  infiltration  rate is higher as water enters
large pores  and  cracks.   The  infiltration rate is  reduced  rapidly  to a near
steady-state value as the  large  pores  fill  and clay particles swell.  Infil-
tration rates are affected  by  soil texture and  structure, ionic composition of
the applied  liquid, condition  of  the soil  surface,  and type of vegetation.

     Another soil  characteristic  important   in  terms  of  potential  migration
of  hazardous  compounds is  the  depth  to an  impermeable layer,  bedrock,  or
groundwater   (including seasonal  variations).   The depth affects  the drain-
ability  of  the  soil  and  the  effective depth for  pollutant  attenuation.   It
may also indicate whether  leaching to groundwater poses  an acute  hazard.

     Ryan and  Loehr  (1981) reported  that  with  depths   of  less  than  1.5  m,
horizontal flow  predominates and  the saturated  hydraulic conductivity can be
assumed  to  be equal to the permeability of  the  saturated horizon  with the


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highest permeability.   The  hydraulic gradient  is  assumed  to  be equal to the
slope of the  limiting  layer  and  can be approximated by the slope of  the soil
surface.  When the  depth  to  an impermeable layer, bedrock, or  groundwater  is
greater than  1.5  m, vertical  flow  is predominant.   The saturated hydraulic
conductivity of the soil  can  be assumed to  be  equal  to  the  permeability of the
most  limiting horizon,  and the  hydraulic  gradient  is  assumed to  be one.

     An assessment  of  the flooding frequency of the  site should  be made
to determine  potential  for off-site  migration  in floodwaters.   Only  slight
hazards exist if the soil is usually not flooded  any part  of  the year, moder-
ate hazards  if  occasional  flooding  occurs (10-50  percent  chance of  flooding
once every two years) and severe hazards if frequent flooding occurs  (greater
than 50% chance of flooding every  two  years)  (Ryan and  Loehr 1981).

     Potential for  off-site  migration  in  runoff  can  be  predicted  by  site/
soil  characteristics  and  waste characteristics.   Various  runoff models have
been  developed  and  can be used as  predictive tools.    (See  Huber and Heaney
(1981)  and Foster  (1981)  for  reviews  of  available models.)   If the situation
warrants,  precautionary methods  to  reduce erosion should be  included  as  an
important and necessary part  of an  in  situ  remedial  treatment  plan.

     Runoff is  the  portion  of precipitation  that  appears  in surface waters.
Technically runoff  not  only  includes surface and  subsurface  runoff  but also
movement of water  vertically  to groundwater  and then   lateral movement of the
groundwater to  surface receiving  waters  (baseflow).  Surface  runoff  is  water
that  travels  over  the  ground surface to  reach  a lake  or  stream (overland
flow).  Subsurface  runoff  is  water  that  has   infiltrated the  surface  soil and
moved laterally through the vadoze zone to  the receiving  water as  shallow flow
above the groundwater (interflow). Because  the pathway  that water  takes to the
receiving water determines what type and  how  much  of a  chemical  is transported
to that water,  the three types of  runoff  need  to be  estimated separately  to
assess  potential problems. Surface  runoff  may carry chemicals  in  solution,  in
suspension, or  adsorbed  to  suspended soil particles.   Subsurface runoff and
groundwater carry  primarily  soluble chemicals  not  strongly  adsorbed  to soil
particles.

     Steenhuis and  Walter (1979) describe  a method  of  categorizing  pollutants
with  regard to potential  losses in  soil  and water according  to  their  relative
concentrations  in  water  and  on soil  particles as  indicated by  adsorption-
desorption  isotherms.   An adsorption partition coefficient,  ks,  for a  given
solution concentration is a calculated as the ratio of  amount  adsorbed to that
in solution:

     ks =

     concentration of substance adsorbed  to soil particles  (ppm; mg/kg)
            concentration of  substance in solution (ppm;  mg/1)

Group  I pollutants  are  those  with ks  values  approximately  equal   to  1000.
These  include  the  strongly  adsorbed and  solid  phase pollutants.  The loss  of
tnese pollutants in baseflow  and interflow is small.   Their losses  in  overland
flow  are  high  ana  are related to the amount  of sediment in  the soil  and the

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amount of  substance  in  the soil.  Organic matter,  which  may be an  important
sorbent  of hazardous compounds,  is more easily eroded than most mineral
particles and tends to remain in suspension because of  its  low density.  Silt
and clay  are  also more credible than sand and  are usually higher in organic
matter content,  which may be adsorbed on the clay  particles.  Clay is also an
important sorbent  of  hazardous  compounds.   Therefore,  an "enriching process"
occurs in overland runoff  in which  the  concentration of  a  hazardous compound
in an eroded  sediment may  be much  higher than  in the original soil.   Loss of
Group  I  pollutants  can be  decreased  by erosion control  practices  which
minimize sediment detachment  and transport.

     Group II pollutants,  with  ks  values of about 5,  include the moderately
adsorbed pollutants (e.g. most  pesticides).  Their loss in overland flow has
been shown to be  related to  the amount  of runoff water and not to the amount
of soil  loss.   Erosion control practices  which prevent  sediment detachment and
transport are not  as  effective  as  practices  which reduce the total  amount of
runoff volume.  Transport of adsorbed substances by water passing through the
soil  matrix  is  much  slower  than  transport  by   surface flow.  An equilibrium
exists between  substances  dissolved  in  the soil  water and  those adsorbed to
the soil.  The  greatest  pollution  of sub-surface flow water comes from those
substances which are  weakly adsorbed  or  those slow  to degrade.

     The Group  III pollutants have  ks  values of about  0  to 0.5  and  are non-
adsorbed or  soluble  pollutants.   Their  primary pathway  of  loss  is through
interflow and baseflow.   Losses  in surface runoff  are  small and therefore are
not greatly affected by practices  to reduce  runoff.    In fact, reduced runoff
might increase subsurface flow and  thus  increase  their  losses  to  interflow and
groundwater.

     Moderately  and weakly adsorbed  substances  usually migrate fairly rapidly
after application  to  the  soil   with  initial  precipitation  events.   Strongly
adsorbed substances,   depending  on  their recalcitrance, may pose hazards for
years due to  movement  in  overland flow.

     The control  of  runoff can  be  accomplished  by  several  means  (Steenhuis
and Walter 1979).  Decreasing runoff velocity will reduce both surface runoff
volume and sediment loss.  More water remains on the soil for a  longer period
of  time,  thus  permitting  increased  infiltration.   Runoff velocity may  be
reduced  in several  ways:  1) by forcing water  to  move laterally rather than
straight down  slopes;  2)  by  reducing  the  slope  of  the  land  through  land-
forming;  or 3)  by increasing  the roughness  of  the soil surface to  dissipate
the kinetic energy of  the water.

     An  increase  in   surface  storage will  remove  trapped  water  from  total
surface runoff  volume, thereby  resulting in  decreased  runoff  velocity  and  a
reduced  sediment  carrying  capacity.    Surface  storage can be  increased  by
various engineering and  agricultural practices   (e.g.,  creation  of  ridges of
soil  or  vegetation) which  allow water to pool.   Moisture storage capacity in
the soil  itself  can be increased by  addition of  organic matter or by draining
or evaporating moisture already  in  the scil profile.

     Infiltration governs the amount  of water  that will  enter  a soil.   Thus
engineering  and  agronomic practices that  affect the physical, chemical,

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and biological  soil characteristics may alter infiltration rates.  Changes  in
bulk density, porosity,  and  percent of water-stable  aggregates  all  affect  a
soil's  capacity for infiltration and its erodibility.  Infiltration rates  can
be increased by lower bulk densities and higher porosity or by an  increase  in
the number of macropores  connecting to  the  soil  surface.

     Frozen  soil  often  has  a  lower   infiltration  rate  than  unfrozen  soil,
especially if the soil was frozen when moist.   Since  frost usually penetrates
deeper  if soil  is  bare than  if  it  is snow covered,  practices that prevent snow
from blowing away may lessen frost  penetration.  However, the additional snow
may  increase surface  runoff.    Snowmelt  occurring  in  the spring,  often   on
frozen  ground, can carry  a  higher  contaminant load than rainfall runoff that
has  infiltrated the  ground.    Also the time  frames  in  which  rainfall  runoff
and  snow  melt  runoff occur  are different.    Rainfall runoff  occurs  when  the
infiltration capacity of  the  soil   is  exceeded  by  the rate of precipitation.
The  infiltration  capacity may  be  exceeded  by  the  intensity  of  the rainfall
event  and/or its   duration.   Spring snowmelt occurs over  a period  of time
interrupted  periodically  by  subfreezing weather and continuing  until  all  the
snow melts.

     Runoff  can also  be controlled  by reduction of the splash-energy  of
falling  rain.   Raindrop  impact on  bare  soil  may break  soil  aggregates   to
component  particles.   These smaller particles  may be  carried  by water into
larger pores, thus  forming a  thin surface  layer with low hydraulic con-
ductivity.   Dissipating  raindrop energy by use of a plant canopy or mulch  or
promoting  aggregate stability with  organic matter  addition may greatly reduce
this surface sealing effect.

Off-site Migration in Air--
     Soil  properties  that affect  off-site migration of hazardous  compounds
via  air  transmission also  need to be  characterized.    Again,  the degree  of
migration  in air  is  an interaction  between  soil/site  characteristics  and
waste characteristics.

     Important soil properties  that determine  the extent  and rate  of  volatili-
zation of  hazardous compounds are  those related to  soil  permeability  and soil
moisture.   The total  porosity of  the soil,  the  distribution  of  macro  and
micropores,  and the tortuosity  of the  soil  pores should  be  characterized.   The
range  of  air-filled  porosities  exhibited  by the soils under moisture  regimes
encountered  at the  contaminated site  also  should be  investigated, for wetter
soils  are  less permeable to gases than  dry  soils.   At  lower moisture  contents,
there  is  also  an   increase  in  sorption of  compounds.   Volatilization  of com-
pounds from  soils  is more completely discussed in  section 6.

     wind  erosion, unlike water erosion, is not divided  into types but varies
only by  degree.   The major factors  affecting erosion  by  wind  are  climate,
soil,  and vegetation.   Specific  factors  are  shown  in  Table 3-17.   A wind
erosion model has been developed by Chepil  and Woodruff  (1963) to predict soil
loss from wind erosion.

Geological and Hydrogeological  Factors--
     In  addition  to  soil characteristics,  geological information  in the form
of  subsurface  geological  characteristics  and  nydrcgeological  factors  are

                                      56

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 TABLE 3-17.   FACTORS AFFECTING EROSION OF SOIL  BY  WIND  (SCHWAB ET AL. 1966)
                   Used by permission, see Copyright  Notice
Climatic  Variables         Soil Factors              Vegetative Factors


Precipitation              Texture                   Height  and density of
Temperature               Structure                   cover
Wind                      Particle density          Type of vegetation
Humidity                   Bulk density              Seasonal distribution
Viscosity of  air           Organic matter
Density of air             Moisture content
                          Surface roughness
important in determining potential  for offsite migration via transmission by
water to ground or surface receiving waters.  The nature of groundwater flow
systems within the subsurface structure  is  an -important  factor which deter-
mines the impact hazardous wastes may have on the  environment.

     The geological  framework  of the site consists of the rocks or sediments
in the  formations beneath the  site.   Information is required  on the extent,
composition,  stratification,  and  thickness of the  layers.   For example,
sedimentary  layers (e.g.,  limestones,  sandstones, and shales) tend to channel
flows  along bedding planes.   Thus,  flow directions  may  be determined by
dips in  the strata.   In humid  climates,  solution channels  may  form in lime-
stones, which  may  allow  very rapid transport of pollutants over  long distances
with  little  attenuation.    Fracture zones  that  occur  in  igneous  and  meta-
morphic bedrock  (e.g. granites, diorite, marble,  quartzite, slate, gneiss, and
schist), may also  permit rapid transport of polluted  groundwater  (Blackman et
al.  1980).   The most favorable  areas would be those  covered  by  thick deposits
of unconsolidated  low permeability materials overlying shales or undisturbed
fine-grained sedimentary bedrock formations  which  have no  major  structural
variations  or fractures affecting  formation  stability  (Corbin  1980).   Large
thicknesses of unconsolidated materials allow opportunities for  natural
attenuation while  providing  a  protective  barrier to  any usable  aquifer
system.

     Hydrogeological  factors relating  to  groundwater  are   also  required  to
assess  potential  for pollution from  hazardous waste  contaminated  soils.
For  groundwater  in  unconsolidated   formations,   less hazard exists  if  there
is no  connection with  surficial or  buried drift  aquifers,  especially if
the  hazardous waste  site  is  overlain with lower permeable  materials  to
bedrock.   For groundwater  in  bedrock  formations,  more favorable  conditions
to minimize pollution  potential from  hazardous waste  sites exist  if the
site is away from  any recharge  areas to major freshwater  aquifers or there is
no direct  connection  to a  usable  bedrock  aquifer  (Corbin  1980).   Confined
groundwater, which is isolated from  the  surface  by  a relatively impermeable
bed  consisting of  clay,  shale, or dense limestone, is not easily contaminated,
nor is it affected much  by local sources of recharge  (Warner  1976).

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     Knowledge of the  nature  of groundwater flow  patterns  is also  critical.
Localized, rather than  regional,  groundwater  flow  patterns,  preferably with
known discharge points  and  a large distance to  the  water table  are the most
favorable conditions.   Information  required  to  assess  hazard might  include:

     1.    Elevations of  water  table  and potentiometic  surface   (groundwater
gradients).

     2.   Fluctuations of groundwater levels due  to natural inputs  and outputs
of water.

     3.    Drawdowns  of  groundwater  levels  from  wells   (cones  of depression
caused by pumping  can  alter  groundwater  levels  from those that would  naturally
exist).

     4.    Effects  on groundwater flow patterns  from  changes  in surface water
flows or levels.

     5.    Hydraulic  characteristics of  the  aquifer  including transmissivity,
specific yield,  and  specific retention.

Specific yield and  specific retention  are  measures  of  the amount of ground-
water an  aquifer  will  yield upon  pumping.   Specific yield  is  the  amount  of
water that will  drain by gravity from a  saturated aquifer  divided  by the bulk
volume of the aquifer.   Specific retention  is  equal  to the porosity  minus the
specific yield  under saturated  conditions.    Transmissivity  is   the rate  at
which water  is transmitted  through a unit  width of  the  aquifer  under a unit
hydraulic gradient.   It is  equal  to the  permeability  multiplied by  the aquifer
thickness (U. S.  Environmental  Protection Agency  1977).

Meteorological and Climatological  Data--
     Meteorological  and climatological  data are  required to assess the public
health  hazard from  migration  of hazardous  compounds  to  receiving ground and
surface waters and  via  air  transmission.  These factors also impact upon the
attenuation of hazardous compounds  in the soil  environment.

     The  dispersion  characteristics of  the area are  an important  component
of  the   air  migration  potential.   Greater  dispersion   associated  with open
lands  is more favorable  than  areas  with  channel  type  dispersion, such  as
in valley and depressional  areas.   Determination  of prevailing wind directions
and  wind  velocities will give  an  indication of  the  direction  and  extent  of
migration.

     Temperature  of both  the  air  and soil  affect  the rate of biological and
chemical  attenuation processes  in  the  soil, the volatilization of compounds,
and the soil  moisture budget.   In  general, temperature is difficult to control
in a field situation, but may be  affected by  the use of  mulches of natural  or
artificial materials and soil  moisture  control.

     Most  soil  microorganisms  are mesophiles, i.e.  they exhibit maximum
growth  and activity  in  the  20 to 35"C temperature range.  Soils  also contain
some microorganisms which grow best at temperatures  below  20C  (psychropiles)


                                      58

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and some which exhibit maximum growth  rates  between  50 to 60C (thermophiles).
In  general,  organic  matter decomposition  increases  with  increasing tempera-
ture.   The influence of temperature on microorganism activity  should be
considered to estimate the time for  site  recovery.

     Soil  temperature data are  not  as  extensive  as  air  temperature  data.
K.  W.  Brown  and Associates,  Inc.  (1980)  discuss a method for predicting
annual soil temperature cycles developed by Fluker (1958).   They also present
isotherm maps of soil  temperature data  at  the 4-inch depth for the spring of
1979 in the United  States.

   The preparation  of a water  budget for  the contaminated hazardous waste site
will aid  in  indicating  leaching  potential  and predicting  the type and extent
of  attenuation processes  that  will  act  upon the waste (biodegradation,  sorp-
tion,  etc.).   Inputs  to  the  site  include precipitation and  any  added  water
that  may be  necessary for execution of the appropriate   in  situ  treatment
technique.    Factors  which  may  limit required water  addition  must  also  be
considered,  such  as  the  total  amount  of  precipitation  relative  to  evapo-
transpiration, the distribution of precipitation during  the year,  and changes
in  precipitation from year  to  year.   Outputs  include evaporation,  transpira-
tion, percolation  to  the groundwater,  and subsurface and surface runoff.

     Precipitation  data may be based  on real  measured  rainfall  events  or on
frequency  analyses,   (e.g.  amount  of  precipitation expected  in  a 10-year,
24-hour  storm,  25-year,  1-hour  storm,   etc.).   Of  importance  is  the  total
rainfall a site receives  as well as the  intensity, duration, and frequency of
single precipitation  events.

     Evaporation  is  the transfer  of  liquid water into the atmosphere.  Factors
affecting the rate of evaporation are the  nature  of  the  evaporating surface
and the  vapor pressure differences as  affected by temperature,  wind,  atmo-
spheric pressure, quality  of water,  and available energy (Schwab et al. 1966).
In  saturated soils,  evaporation  is  expected  to be the  same  as from  open
freewater  surfaces.    However,  in  unsaturated  soils,  below  field  capacity,
evaporation is very  low,  as soil moisture movement is  slow  when  the soil  is
relatively dry.

     Transpiration  is the process by  which  water  vapor  passes  into the  atmo-
sphere through the tissues  of  living  plants.   Loss of  soil  moisture by  tran-
spiration is often  a  substantial  portion  of the  total water available during a
growing  season.   Transpiration  is  dependent  on the moisture  available,  the
kind and density of  plant growth, the amount  of sunshine,  and soil  fertility
and structure.

     The  measurement  of  evaporation  and transpiration  is  usually  combined
and  referred  to  as   evapotranspiration.    Evapotranspiration  can   either  be
measured directly or predicted  using  various models (e.g.  see Schwab  et
al. 1966 for a discussion  of methods).

The Receiver System--
     The  receiver  system  around  the  hazardous  waste  contaminated  site  may
be  an  important  site  charactertistic,  which, when evaluated  in  conjunction


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with  waste  characteristics,  may  determine  precautions  necessary  to  prevent
migration of hazardous constituents  and  also  may dictate the remedial  action
appropriate for the  specific  site/soil/waste situation.  For  example,  a
contaminated site  located in  a sparsely populated  arid region  over a deep
unusable aquifer may  not  require the  use of  a quick-acting remedial  in situ
treatment technique.   However,  a site in  an  urban area,  with high  rainfall  and
soils of high erosion  potential, overlying a heavily  used aquifer,  may require
the  choice  of   an  in  situ treatment technique  with little  or  no  secondary
health impacts  and  which  can  treat  the wastes  in a shorter span of  time.

     The characteristics  listed  in Table 3-18 can be used  to give  an assess-
ment of hazard potential.  Information from organized hazard  ranking  systems,
such as the Mitre Hazard Ranking System Model,  the LeGrand  Model,  the Surface
Impoundment  Assessment  Model,  the  EPA  Solid  and  Hazardous  Waste  Research
Division Model,  and the Rating  Metholodogy Model (Caldwell et  al.  1981)  may be
available or be  used  to  obtain  an indication of the urgency of clean-up  and
required precautionary methods.
                TABLE 3-18.   IMPORTANT RECEIVER CHARACTERISTICS
Migration to Groundwater

   Groundwater use - present and potential
   Groundwater quality-usability of aquifer
   Distance to nearest downgradient well-treatment  of water  from  the  well
   Population served
   Discharges to surface waters - uses of surface waters
   Recharge zone for freshwater aquifer


Migration in Runoff to Surface Waters

   Surface water use - drinking, recreation,  fishing, irrigation,  livestock
      watering
   Population served
   Distance to a sensitive environment - floodplain,  wetlands,  etc.


Migration via Air Transmission

   Distance to nearest human population
   Population within 1 mile radius
   Population downwind from site
   Land use - crops, forestry products, livestock,  urban,  schools,  parks,
      playgrounds, industrial, residential, etc.

   Distance to a sensitive environment
                                      60

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Site Characteristics with Regard
to In Situ Treatment Techniques"

     Soil  and  site  characteristics  necessary for  the choice  and design  of
in  situ  treatment  techniques  overlap  significantly with  the  data  required
to  assess  the  potential  for  off-site migration  of  hazardous compounds  from
contaminated sites.  Many of the  natural  attenuation  processes which  determine
migration  potential  may  be used  as  in  situ techniques but under  engineering
management control  and  monitoring.   Therefore, the  characteristics  listed  in
Table 3-2 are also relevant for choosing  appropriate  treatments  for degrading,
transforming,  or  immobilizing  hazardous  compounds.    Those characteristics
which are subject to some degree  of  engineering control  are indicated  in  Table
3-2.   The  remainder of  this  chapter is  devoted to  the  discussion of  soil
attenuation processes related  to hazardous waste  treatment.  In Section  2  of
this manual, various treatment processes based on  soil  attenuation properties
are discussed.

Site Characterization Related  to  Physical
Execution of In Situ Treatment  Technology

     Site  requirements  for the  physical   execution  of an  in situ  treatment
technique may be a determining  factor in  whether the  technique may  actually  be
utilized  at  a  particular  site or  what  precautions  or operational   controls
need to be incorporated into the  execution  plan.

     The  trafficability  of the soil  under different climatological   and  soil
moisture conditions  needs  to  be assessed.   There may be  restrictions on the
type of  equipment  that  can be used  and  times  when the equipment  can be  used
(e.g.,   presence  of  boulders,  steep slopes,  excessively  wet  conditions  in
clayey soils).

     Trafficability refers to the capability of a  soil  to  permit the movement
of  a vehicle  over the  land  surface (Reeve  and  Fausey  1974).    In  military
operations, trafficability  is  defined as  whether  or not  vehicles  of various
kinds can pass over  a given terrain  without  regard for the final condition  of
the  soil.   However, in  agriculture,  the  primary concern  is  for successfully
performing  given  operations on  the  land  without  damaging the soil.    Such
damage might include decreased permeability to air and  water, altered thermal
relations,  and  resistance  to  root  penetration.    Generally,  trafficabi1ity
means being  able to perform required operations in such a way  as  to  create a
desired soil condition  or  to  get  an operation completed  expediently.  Opera-
tions that  require manipulation  (tillage)  require a  different  interpretation
of  trafficabi lity  than  do operations in which soil   is used  as a  surface  on
which to operate (non-tillage).

     The  U.  S. Army Engineer  Waterways  Experiment Station (1956) identified
four soil characteristics that relate to trafficability of  soils:  1) bearing
capacity, 2) traction capacity, 3)  siipperiness,  and  4)  stickiness. Any one  or
a combination of these may cause  vehicle  immobilization.

     The  traf f icabi lity  of a  soil   is  considered adequate for  a  vehicle  if
it  has  sufficient  bearing capacity  to  support  the  vehicle  and  sufficient


                                      61

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traction to  develop  the  forward thrust  necessary to  overcome the  rolling
resistance.    Bearing  and  traction  capacities are  related  to  soil  strength
or  shear  resistance.    Soil  strength can  be determined by  laboratory  tests
(direct  shear,  triaxial  shear,  and unconfined  compression)  or  by  a  field
test using  a cone penetrometer.

     Slipperiness is  the condition  of  deficient  traction capacity  in  a  thin
surface layer of  soil which  is  otherwise  trafficable.   When  soils  adhere and
build up on the running gears of a  vehicle,  increasing rolling resistance and
making  steering  difficult, the  condition  is called sticky.   Soil  stickiness
and slipperiness  usually occur  on soils high in  clay.   When  the soil  surface
is cooler than the underlying  soil,  moisture  migrates from the lower layers to
the surface.   If the evaporative demand  is not great,  the  moisture  accumu-
lates at the  surface  and  causes decreased  traction.   This  condition is  not a
problem which can be  alleviated  by  drainage,  but by water  management.   It is
especially  a problem in  seasons  when the radiant  energy input is low.

     Damage to the soil  by vehicular traffic usually results  from compressing
and puddling the soil.  To avoid such damage, the soil must be manipulated or
traversed  when the  soil  is below  some critical  moisture  level, which is
dependent on the type  of  soil.   Wet  soils are easily compacted by both tillage
and nontillage  operations.   Clay soils  are  especially  a problem,  since  they
hold  a  large  amount  of  water  that  must  be  removed by  internal  drainage or
evaporation before tillage  is  possible.

     Soil compaction can  be reduced  in several  ways.  Reducing the  load
intensity on a soil or reducing the number of trips over a soil can be accom-
plished by  changing machinery  configurations or  tractor tire  designs.   Sub-
surface and surface drainage  systems can also be used to reduce soil moisture
content.

     Other  site conditions which may affect trafficability include slopes and
the presence  of  large coarse fragments, such as boulders.   Reeve  and Fausey
(1974)  present  a  review of methods  regarding the determination of soil  traf-
ficability  using predictive equations and empirical rating systems.

     If the treatment itself requires a certain  site condition, modifications
must be made,  if  possible, to  achieve  that condition.   An assessment must be
made to  determine if  required modifications are feasible  at  that particular
site.   For  example,  the  initial   steps  in  biodegradation  of  a chlorinated
organic compound  may  require  anaerobic  conditions  followed  by aerobic condi-
tion.   Thus  the site/soil  infiltration,  permeability,  and drainability
characteristics  all   determine  whether  anaerobic/aerobic  conditions  can  be
achieved.

Sources of  Information

     Many  hazardous  waste sites  for which  in  situ  treatment may  prove to
be  an  appropriate remedial  response  may  have been subjected to  earlier
acute  emergency  response  cleanup   actions  or preliminary  investigations  to
determine the necessity of remedial  action,  such as a Superfund site.  There-
fore, there may be significant  existing  data  on site and  soil characteristics.


                                     62

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The necessary  data  required to assess  the choice and execution  of  an  appro-
priate treatment or series  of  treatments has  been  discussed  generally in this
section  and  will be  discussed in  greater detail  in the following  sections
relating  to  soil attenuation  processes.    Existing  data  should be  assessed
to  determine  adequacy  for  meeting  information  requirements  and  to  design
any subsequent  data collection activities.   If  data are sufficient,  no  new
characterization efforts  are needed.    If  further data collection  is needed,
trained soil  scientists, geotechnical  engineers,  geologists,  and other persons
trained  in appropriate  disciplines  should  be hired  to generate  the  required
information.

     Some sources of existing information  include the following:

     1.   Government  investigative  reports  (e.g.,  Field  Investigation  Team
(FIT)  reports,  Hazard Assessment Reports (Mitre  Model)

     2.   Engineering  data  from  other public  or private  agencies  or  firms
(e.g., university  geology departments, state water  resource  agencies,  state
geological surveys,  city water departments)

     3.  County soils maps (general  background i-nformation--on-site  investiga-
tion also required)

     4.  Aerial photographs

     5.  Water well  borings logs

     6.  Geotechnical  reports from nearby  facilities

     It  is expected that  data related to  potential  migration from  the  site
(route characteristics)  and potential  public health  hazards   (waste and  re-
ceiver characteristics)  will have been  generated for  many  sites where in situ
treatment  is being  considered.    Most new  data collection  efforts will  be
expected  to  emphasize   information  required  for the  choice  and  execution  of
appropriate  successful  in  situ treatment  technology,  i.e.,   the  information
will center  around  soil  characterization.   Therefore, persons knowledgeable
in soil  science  should  be utilized  for sampling  and  analysis  of  soil samples
and for the  interpretation of sample results.


WASTE CHARACTERIZATION  RELATED TO  IN SITU  SOIL TREATMENT

Introduction

     The  hazardous-waste  contaminated  site must be  thoroughly characterized
in terms of  waste characteristics in  order  to assess  the  degrees  of hazard to
both on-site workers and  to off-site  populations and  to determine  applicable
and appropriate  types of  in situ  treatment technology.  Together with  knowl-
edge  of  soil  and   S'lte  characteristics,   knowledge  of waste  characteristics
will enable  the selection  of a  particular treatment technique  specifically
designed for the site/soil/waste  situation or will  indicate whether in  situ
treatment is  not appropriate for the specific  situation.


                                      63

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     Since  the  wastes  at a  contaminated  site do  not  exist  separately from
the  soil,  measurement  of waste  types, amounts,  and distributions  must  be
assessed  as part  of  the soil, soil  pore  liquid,  groundwater,  or surface or
subsurface  runoff.   Thus analysis techniques  will usually include both
extraction  procedures to  separate  waste  constituents from the environmental
matrix as well  as chemical  analyses  of  the  constituents.   It  is not practical
to  use   identification   based  on observable  characteristics,  such  as  odor,
color, reaction, etc.   In  general, analysis of  substances classified as
hazardous  requires  more sophisticated methods  and  instrumentation than
traditional  waste  parameters  in  pollution control,  such  as  chemical  oxygen
demand,  nitrogen forms,  phosphorus,  etc.

Definition  of  Hazard  and  Degree of Hazard

     A waste stream is  characterized  as hazardous  if  it  is  defined  as hazard-
ous, or if  it  contains  substances which are defined as hazardous (40 CFR 261),
or  if  it exhibits one  or more  of  the characteristics  of hazardous  waste:
ignitability,  corrosivity, reactivity, or toxicity.

     Ignitability refers to  wastes  that either  present  fire hazards  during
routine  storage, transportation,  or  disposal or are  capable  of  severely
exacerbating a  fire  once  started.   Corrosivity identifies  wastes which have
the  ability to  mobilize  toxic  metals  when  discharged to a land  environment,
corrode  handling,  storage,   and  management equipment,  or destroy  human  or
animal tissue  in  the  event  of  inadvertent  contact.   Reactivity  refers  to
wastes which  have  any of the  following  properties: ~TJreadily  undergo
violent  chemical  change;  2)  react  violently  or  form potentially explosive
mixtures  with  water;  3) generate toxic fumes when  mixed  with water  or,  in
the  case of cyanide  or  sulfide-bearing wastes,  when exposed to  mild  acidic
or  basic conditions;  4) explode when subjected to  a  strong  initiating  force;
5)  explode  at  normal  temperatures and  pressures;  or 6)  fit  within the Depart-
ment  of  Transportation's  list of  forbidden  explosives  (49  CFR  173.53),  or
Class B explosives (49  CFR 173.88).

     Toxicity,   as  used  in defining  a  hazardous   waste,  refers to a reading
of  toxicity in  the  Extraction  Procedure  (EP)  Toxicity  Test.    The  EP is
designed to simulate  leaching of  waste  in  a sanitary landfill.   It is  a
laboratory  test  in  which  a representative  sample of a  waste   is extracted
with distilled water with pH maintained at 5  by  acetic acid.  The  EP extract
is  analyzed to  determine if threshold  levels  for eight metals,  four  pesti-
cides, and  two herbicides (Table  3.19)  have been  exceeded.   If  the  EP extract
contains one or more of the substances in amounts equal  to or exceeding  the
specified  levels, the  waste is classified  as  hazardous according  to the
Extraction  Procedure  Toxicity Test.

     Definitions of methods to determine  these characteristics are presented
in  Test  Methods for  Evaluating Solid Waste:  Physical/Chemical  Methods   (U.S.
EnvironmentalProtectionAgency1982b).In a  contaminated environmental
sample,  it  may  be difficult to determine if the waste  substances exhibit
these hazardous characteristics.  Chemical  identification may be  the  only  way
to  determine  which  waste constituents  are undesirable  and  thus require  in
situ treatment.


                                     54

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TABLE 3-19.   MAXIMUM CONCENTRATION OF CONTAMINANTS FOR CHARACTERISTIC
    OF EP TOXICITY (U.S.  ENVIRONMENTAL PROTECTION AGENCY 1982b)
EPA Maxiumum
Hazardous Waste Concentration
Number Contaminant (mg/1)
D004
D005
D006
0007
D008
0009
D010
D011
D012
D013
D014
D015
U016
D017
Arsenic
Barium
Cadmium
Chromium
Lead
Mercury
Selenium
Si Tver
Endrin (1,2,3,4,10,10-Hexachloro-l
7-epoxy-l,4,4a,5,6,7,8,8a-octahydro-l
4-endo, endo-5,8-dimethanonaph-
thalene)
Lindane (1,2,3,4,5,6-
Hexachlorocyclohexane, gamma isomer)
Methoxychlor (l,l,l-Trichloro-2,2-bis
(p-methoxyphenyl jethane)
Toxaphene (CiQHioCis, Technical
chlorinated camphene, 67-69%
chlorine)
2,4-D (2,4-Dichlorophenoxyacetic acid)
2,4,5-TP (Silvex) (2,4,5-
5.0
100.0
1.0
5.0
5.0
0.2
1.0
5.0
0.02
0.4
10.0
0.5
10.0
1.0
                Trichlorophenoxypropionic acid)

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     Other waste characteristics are  important  in  determining  degree  of
hazard,  though  not  legally  defined  as  such.   These  include various  types
of  human  toxic  effects,  animal toxic  effects,  persistence/biodegradabi1ity,
infectiousness, volatility (affecting migration  via atmospheric route),
and  solubility  (affecting  migration  via water  routes)  (U. S. Environmental
Protection Agency 1982b).   These must  also be assessed  in  order to  select  an
appropriate treatment technology  which   is effective  and  ensures  safety  for
both on-site workers  and off-site populations.

     Toxicity  information  is  available  from many  different  sources.    The
following   is  a  partial  listing of reference publications  and systems  which
may  be  consulted for human and/or  ecological toxicity data and  chemical
hazards:

     1.    Chemical  Hazards  Response  Information  System  (CHRIS),  U.S.  Coast
Guard,  consists  of  four handbooks  (A  Condensed  Guide  to  Chemical  Hazards,
Hazardous   Chemical  Data  Manual,  Hazard  Assessment  Handbook,  and  Response
Methods  Handbook),  data bases  for  regional contingency  planning,  and  the
Hazard Assessment Computer  System.

     2.   Oil  and Hazardous  Materials Technical A-ssistance Data System
(OHM-TADS) is an automated  information  retrieval  file  designed to  facilitate
the  rapid retrieval  of  information  on  approximately 1000  chemicals.    In-
cludes  information  on  physical,  chemical,  biological,  toxicological,   air,
land, and  water  effects  and  commercial data.

     3.    Chemical Transportation  Emergency  Center  (CHEMTREC)  serves  as
clearinghouse  by providing  an emergency 24-hour  telephone  number for chemical
emergencies.   Provides  warnings  and  limited  guidance  on  hazards  of  spills,
fire, or exposure,  and contacts shipper  of the chemical.

     4.    TOXLINE (Toxicity  Information  On-Line),  National Library of  Medi-
cine, is  a computerized data  resource  for health  and  toxicological  effects
information.

     5.     NIH/EPA  Chemical  Information System  (CIS),  Interactive  Sciences
Corporation,  Washington,  D.C, contains  information on toxicological, analyti-
cal, and physical properties of chemical  substances.

     6.    Organic Chemical  Producers  Data  Base,  EPA/ORD Cincinnati  Research
Laboratory,  contains data  on  physical/chemical  properties, manufacturing
processes, uses, and  by-products.

     7.   Karnofsky, B.,  J. King,  P.  Thielmann, K.  Gleason, and M.  Baer.
1981.   Chemical  information resources  handbook:   Toxics integration informa-
tion series.    EPA-560/TIIS-81-001.   Office of  Pesticides  and  Toxic  Sub-
stances,  Washington,  D.C.    This  publication describes chemical  information
resources  dealing  with  chemical  toxicology,  environmental  effects,  spill
responses, disposal  methods,  ambient  air  and water  concentrations,  control
technologies,  and existing  regulations.

     8.   Sax, Irving N.   1975.  Dangerous properties  of industrial  materials.
Van  Nostrand Reinhold Co.,  New  York,  NY.


                                     66

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     9.    National  Fire  Protection  Association.   Hazardous chemicals  data.
Boston,  MA.

    10.    Milson, M.  et al.  (Eds.).   1976.   The Merck Index,  9th Ed.  Merck
and Co., Inc.  Rahway, NJ.

    11.    Chemical  Manufacturers  Association.   Chemical  safety data  sheets.
(SD-l-SD-96).   CMA, Washington,  D.C.

    12.   Fawcell, H.  H.,  and W. S.  Woods  (Eds.).  1981.  Safety and health  in
chemical operations.  2nd ed.,  Wiley-Interscience, New York, NY.

    13.   Bretherick, L.  1979.   Handbook  of reactive chemical hazards.
Butterworths,  Boston, MA.

    14,    National  Institute  for Occupational  Safety and  Health  (NIOSH).
Registry  of  Toxic  Effects of Chemical  Subtances.   Annual  publication.
U.S. Government Printing Office, Washington, D.C.

    15.   Survey of  Compounds  Which have  been  Tested  for  Carcinogenic  Activi-
ty.  U.S. Government Printing  Office,  Washington,  D.C.   Seven-volume  series.

    16.    American  Industrial  Hygiene Association.   Hygienic  guide  series.
Detroit, MI.

    17.    Patty, F.  A.   Industrial hygiene  and  toxicology.   Wiley Inter-
science, New York, NY.

    18.    National  Institute  for Occupational  Safety and  Health.   NIOSH/
OSHA pocket guide to chemical   hazards.   Publ.  No.  78-210,  NIOSH, Washington
D.C.

     A  comprehensive  list of  biological  test systems  which may  be used
to  detect  genetic  toxicity  of hazardous wastes  is  presented  in Hazardous
Waste Land Treatment (U.S. Environmental  Protection Agency 1983).

     Toxicity   of  waste  constituents  to soil  microorganisms  is especially
of concern because  of the effects on biological  in situ  treatment processes.
Acute microbial toxicity  can  be  evaluated  using  a  pour  plate method  which
enumerates total viable  heterotrophic and  hydrocarbon-utilizing  microorgan-
isms.   A  overview  of  this method, which involves  a series  of  soil/waste
dilutions  in phosphate buffer,  is  presented in Table 3-20.

     Another  method  is currently being tested  by  the U.S.  Environmental
Protection Agency (1983) for  evaluation of acute microbial  toxicity in
hazardous  waste land  treatment  systems.  The  Beckman Microtox"1  measures
the  light output of  a suspension  of marine luminescent  bacteria before
and  after  a sample is added.   A reduction  in  light output  signifies the
presence of  toxicants in the  waste sample (Beckman Instruments,  Inc. 1982).

     Soil  respirometry  (monitoring CO? evolution  from soil/waste  samples) may
also be  used to determine effects of the complex  waste  in  the  soil system on
                                     67

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 TABLE 3-20.   METHOD  FOR DETERMINATION OF MICROBIAL TOXICITY OF A WASTE/SOIL
                 MIXTURE (U.S. ENVIRONMENTAL PROTECTION 1983)
         Microorganism                         Type of Media
         to be Enumerated                      for Enumeration
         Total  viable                     Soil extract agar,  with
         heterotrophs                     amphoteracin B.
         Soil  fungi                       Potato dextrose agar or_
                                         soil extract agar with rose
                                         bengal and streptomycin.
         Hydrocarbon  -                    Soil extract agar, with
         utilizing  bacteria               carbon source replaced with
         and fungi                        silica gel oil.  (Prepared
                                         by mixing fumed silica gel
                                         with waste.)
microbial  activity.   In  addition to  monitoring  toxicity,  the technique  can
also be used  to  study the effects of  various  soil  treatments  and  amendments
on  degradation  of organic  compounds   (e.g.,  levels and  timing  of  nutrient
additions,  temperatures,  etc.).   A description of  the  technique  is  presented
in  Hazardous Waste  Land  Treatment  (U.S. Environmental Protection Agency
1983).

Preliminary Waste Identification

    At  a  contaminated  site,  it may  be  possible  to  obtain  a  preliminary
assessment of expected waste constituents  if the  industrial  source  or sources
of  the  wastes  stored at  the site are  known.   Unique hazardous waste streams
are produced from  a  number  of  industries,  including textiles,  paper, leather
products,  primary  metals,  etc.   (U.S.   Environmental  Protection Agency  1983).
The draft  edition of Hazardous  Waste  Land Treatment (K.  W.  Brown  and  Asso-
ciates,  Inc.  1980)  contains a section dealing  with hazardous wastes  by
specific industry.   An update of this  section  is currently  being prepared  by
K. W.  Brown and Associates,  Inc.

     Several  hazardous  waste  generating  activities are  not  specific  to  a
particular  industry but  are  used in many industries to  perform certain
processes.   Examples of  these   activities  include  painting,  electroplating,
and cleaning, which produce paint residues,  metals  and  cyanide,  and solvents,
respectively  (U.S.  Environmental Protection  Agency 1983).   Therefore,  the
presence of  specific hazardous   substances may be  predicted if  the industry
or  industrial process responsible for  the wastes  is known.   Knowledge  of  the


                                      68

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feedstocks used and expected industrial  products  and  by-products  will  indicate
what substances may  be present.    Chemical  analyses  are still required,  how-
ever, to confirm the presence and  the degree of contamination.

     Another  source  of  information  on  waste constituents  at a  site may  be
preliminary site  assessments,  such as those performed by Field  Investigation
Teams (FIT) for the  U.  S.  Environmental Agency.   From such reports,  informa-
tion on  type  and  amount of  constituents   in soil,  groundwater,  and  surface
water samples may be available.


Chemical Analysis  of the Wastes


     In  order to  effectively  design  an  in  situ treatment  technology,  the
types  and  amounts,  and distribution  of  wastes  present  must  be  accurately
known.    Knowledge of  waste source  will  only give  an estimate  of  specific
substances that may  be  present.   Reactions between  different  wastes and  in
the  soil  matrix may  have   created  new  hazardous substances  which  must  also
be  treated.    In  addition   to  the hazardous components  of the  wastes  which
require  treatment  (i.e., by degradation,  transformation,  or  immobilization),
other waste substances which may  impact on  the effectiveness  of  the treatment
process or have adverse effects  on the soil  system must  also be characterized.
Treatment  effectiveness and completeness also can only be determined  by
knowledge of the waste constituents originally present at the  site.

     Identification  of   hazardous  constituents   in  wastes  is  usually  accom-
plished  by  instrumental  methods  rather  than the standard  types of  analyses
commonly  used for  pollution  analysis.    Instrumental  methods  require  more
costly equipment,  a well-equipped  analytical laboratory, and  trained,  skilled
personnel.

     The instrumental  methods used for analysis are:

     1.  Gas chromatography  (GC)

     2.  High-performance liquid chromatography (HPLC)

     3.  Gas chromatography/mass spectrometry (GC/MS)

     4.  Atomic absorption  spectrometer  (AAS)

     5.  Inductively-coupled, argon-plasma  spectrophotometry (ICAP)

     GC and HPLC are used to quantitatively determine contamination  levels  of
known  specific  organic  materials.    Concentration  levels  in the  parts  per
billion range (ppb) can  be   determined.  They are  not  suitable for qualitative
analysis of  unknown  substances.   Different GC  detectors are  available  for
analysis of different classes of organic compounds (Table 3-21).

     GC/MS is primarily  used for  qualitative analysis but recent  improvements
permit  quantitative measurements as well.  A large number of substances can  be
simultaneously analyzed at ppb  or  sub-ppb  levels.


                                      69

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TABLE 3-21.   TYPES  OF GC DETECTORS (U.S. ENVIRONMENTAL PROTECTION  AGENCY  1983)
   Type of Detector
Type of Compounds  Detected
   Flame ionization  detector

   Flame photometric detector


   Electron capture  detector


   Nitrogen-phosphorus  detector
Hydrocarbons

Sulfur and/or phosphorus
 containing  compounds

Halogenated  hydrocarbons
 and phthalates

Nitrogen and/or phosphorus
 containing  compounds
     AAS and  ICAP  are used for  quantitative  determination  of metals  in  the
parts per million (ppm)  or ppb range.   AAS can quantify amounts of individual
metals,  while ICAP  can quantify amounts of several  dozen metals simultaneous-
ly.

     Tables summarizing U.S. Environmental Protection Agency-approved analyti-
cal  procedures  for  16 classes of  organic chemicals and  approved  analytical
procedures  for 80 hazardous materials  are given in EPA Field Guide for Scien-
tific Support Activities Associated with Superfund  Emergency  Response   '("U.S.
Environmental  Protection  Agency 1982a).

     The U.S.  Environmental  Protection Agency (1983)  has  defined  waste
characteristics   important  for hazardous  waste  land  treatment  in  terms  of
determination  of  hazardous  constituents  of the  wastes  and  constituents
which may  affect the  soil  as an  effective  treatment  medium.   These  char-
acteristics are presented in Table  3-22.  The  reader  is  referred to  the
referenced   document  for   a  thorough discussion  of  the  significance  of  the
various constituents.

Waste Characteristics  Related
to Soil  Treatment"

     Wastes identified at  uncontrolled soil  contaminated sites must  also be
characterized with  respect  to properties that  affect  the  behavior  and fate
of chemicals in soil systems.   Knowledge  of properties  that  affect  the
behavior and  fate  of chemicals  also  directly  affect pathways  of  treatment,
or assimilation, of  waste constituents in soil systems.   Pathways  of treat-
ment  include  1) degradation,  2)  transformation, and/or  3)  immobilization of
chemical constituents in  a soil  treatment zone, with subsequent protection of
groundwater, surface water,  and atmosphere.

     Degradation and  transformation reactions  include  chemical and biologi-
cal  reactions  which breakdown  waste constituents resulting in nontoxic
                                      70

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TABLE 3-22.  METHODS FOR ANALYZING WASTE CONSTITUENTS IMPORTANT TO IN SITU
                  TREATMENT (ADAPTED FROM U.S. ENVIRONMENTAL
                            PROTECTION AGENCY 1983)
Element/Compound/
    Property
 Possible Analysis
     Method(s)
Reference(s)
Inorganic chemicals/
properties

    Metals
    Halides
     (bromine,
     chlorine, and
     fluorine)

    Nitrogen forms
    Electrical
    conductivity

    PH
    Titratable acids
    and bases

Organic chemicals

    Total organic
    carbon
    Volatile organic
    compounds
Sample digestion
followed by atomic
absorption spectro-
photometry or_ in-
ductively coupled arc
spectrometry

Various methods
Various methods
Saturation extracts and
other aqueous extracts

Colorimetric or poten-
tiometric
Aqueous waste suspen-
sions
Dry or wet combustion
with C02 determina-
ations; dichromate
oxidation techniques

Purge and trap or
head space deter-
minations: analysis
with GC or GC-MS
U.S. EPA 1982b
U.S. EPA 1979
Page et al.  1982
Adriano and Doner 1982
U.S. EPA 1982b
U.S. EPA 1979
Bremner and Mulvaney
  1982
Stevenson 1982
Keeney and Nelson 1982
U.S. EPA 1982b
U.S. EPA 1979

Rhoades 1982
McLean 1982
U.S. EPA 1979
U.S. EPA 1982b

McLean 1982
U.S. EPA 1979
Nelson and Sommers
  1982
U.S. EPA 1982b
                                      71

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                           TABLE  3-22.  CONTINUED.
Element/Compound/
    Property
 Possible Analysis
     Method(s)
Reference(s)
    Extract able
    organics
      organic acids
      (e.g.,  carboxylic
      acids,  quaiacols,
      and phenols)

      organic bases
      (e.g.,  alkyl,
      aromatic,  and
      aza-heterocyclic
      amines)

      neutrals (e.g.,
      aliphatic  and
      aromatic hydro-
      carbons, and
      oxygenated and
      chlorinated
      hydrocarbons)

      Water  solubles
Residual  solids  (e.g.,
inorganics and rela-
tively nondegradable
forms of  carbon  such
as coke,  charcoal,
and graphite)
Liquid/liquid acid/
base extraction
method:
  Analysis with GC
  with capillary or
  packed columns

  Analysis with GC
  with capillary or
  packed columns
  Analysis with GC
  or HPLC
U.S. EPA 1983
  Variable; further
  study needed

Evaporation of water
from aqueous fraction
of acid-base extrac-
tion procedure
U.S. EPA 1983
U.S. EPA 1983
U.S. EPA 1983


U.S. EPA 1983
products.    Immobilization reactions include adsorption and chemical reactions
which result  in  accumulation  and termination of  constituent  mobility in the
soil  treatment  zone.   Since many  organic  compounds  and  organo-metal1ic
complexes  exhibit  simultaneous  decomposition  and  migration,  the  relative
rates of degradation and mobilization  must  be  considered.

     Characterization of  chemical  contaminants with  respect  to  soil treat-
ment  pathways  (degradation,   transformation,   and   immobilization)   provides
the  basis for establishing  qualitative  and calculational  procedures for
determining  soil  assimilative  capacities   for  hazardous  waste  constituents
or classes of constituents.
                                      72

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     Utilizing this  approach  for  hazardous waste  contaminated  soils  manage-
ment,  all  constituents  and constituent classes  identified  as  associated
with a  specific  uncontrolled  site  can be  classified functionally  into  three
pathways by  which  soil  treatment  occurs.   This approach also  provides  end-
points  for field verification of  treatment effectiveness  and  protection
of groundwater,  surface water, and atmosphere.

      Specific parameters  important  for determining the  behavior and  fate,
and therefore treatment pathways,  for waste constituents  in soil  are  listed
in Table 3-23.    For each  chemical,  or chemical  class, the  information  re-
quired  can  be summarized as:  1)  characteristics  related  to potential  leach-
ing, e.g., water solubility, octanol/water partition coefficient, solid
sorption coefficient; 2)  characteristics related to potential  volatilization,
e.g.,  vapor pressure, relative volatilization  index; 3) characteristics
related to  potential decomposition,  e.g.,  half-life,  degradation rate  bio-
degradability index;  and  4)  characteristics  related  to chemical  reactivity
e.g.,  oxidation, reduction,  hydrolysis  potential.   Interfacing these  "soil-
based   behavorial  characteristics"   with specific  site  and soil  properties
allows  a determination of the  potential for:  1)  soil treatment and 2)  offsite
contamination.  This information,  then, provides a  rational basis  for  selec-
tion of treatment techniques that augment natural soil  processes to accomplish
complete treatment of the waste.

Statistical Considerations

     A  sampling  and  analysis plan  for characterization  of wastes  at a  hazard-
ous waste contaminated site must be  based on fundamental  statistical concepts
such that  the uncertainty  of  general  conclusions  based on  partial  knowledge
can be  evaluated.    Table  3-24  presents basic  statistical   terminology  asso-
ciated  with  a sampling/analysis strategy.   The  primary objectives of  such  a
strategy are to  collect  samples  that will allow  sufficiently accurate  (close-
ness of a sample to  its true value)  and precise  (closeness  of  repeated  sample
values) measurements of  the chemical properties of  the wastes.   A complete
discussion  of a statistical  strategy  to determine if  chemical  contaminants
are present  at  hazardous  levels  is presented in  Test  Methods  for  Evaluating
Solid  Waste:   Physical/Chemical Methods  (U.S.  Environmental  Protection  Agency
1982b).

IMMOBILIZATION OF CHEMICAL  CONSTITUENTS AS
RELATED TO  IN SITU TREATMENT

Inorganics

     Rather  than  discuss  all possible  inorganic  pollutants,  this  section
will  be  limited  to   those  inorganics  which  have been  the subject  of  concern
resulting from their toxicity and  those that, because  of their use in  indus-
trial  processes, are  likely to be involved in  an accidental  spill.   The
listing of  inorganic  priority  pollutants as defined by the U.S.  EPA (1976),  is
given  in Table 3-25.  Figure  3-13  illustrates the  frequency of occurrence  of
inorganics  in soils  found  at Superfund  and  non-Superfund  sites  (F.I.T.  Re-
ports).  Table  3-26 lists the percent occurrence for each  element.   The
concentration range  of  inorganics found at Superfund plus non-Superfund  sites,


                                     73

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  TABLE 3-24.   BASIC STATISTICAL TERMINOLOGY APPLICABLE TO SAMPLING PLANS FOR
                          SOLID WASTES (U.S. EPA 1982b)

Terminology Symbol
 Variable (e.g., barium X
or endrin)
 Individual measurement X.
of variabl e
 Mean of all possible y
measurements of variable
(population mean)
 Mean of measurements x
generated by sample
(sample mean)
Mathematical equation
N
Z X.
1=1 n
, with N = number
(Equa-
tion)
(1)
H N of possible
measurements
Simple random sampling and
systematic
n
. ,V'
x n
random sampl ing
, with n = number of
sample measurements
(2a)
  Variance  of sample
                                        Stratified  random sampling
                                        x  =
     Z W.x.
    k=l
with x^ = stratum
mean and W^ =
fraction of popu-
lation represented
by Stratum k (number
of strata [k] ranges
from 1 to r)
Simple random sampling and
systematic random sampling
                                                 t-  -  (Z  X.) Vn
                                                  i    _ _i  i
                                        Stratified  random  sampling
(2b)
                                                                           (3a)
   =  Z W, s.  ,  with s,  = stratum
     k=l       variance and W^ =
               fraction of popu-
               lation represented
               by Stratum k
               (number of strata
               [k] ranges from
               1  to r)
                                                                           (3b)
                                        75

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                            TABLE 3-24.   CONTINUED
    Terminology
Symbol
                                         Mathematical  equation
                                 (Equa
                                 tion)
Standard deviation of
sample

Standard error
(also standard error
of mean and standard
deviation of mean)
of sample

Confidence interval
for ya
                              sx
                              CI
 Regulatory threshold3
 Appropriate number of
 samples to collect from
 a solid waste (financial
 constraints not considered)

 Degrees of freedom

 Square root transformation

 Arcs in transformation
  RT
CI = x _+ t 2Q s- ,  with t 2Q
                   obtained
                   from Table 2
                   in this sec-
                   tion for
                   appropriate
                   degrees of
                   freedom

Defined by EPA (e.g., 100 ppm
for barium in elutriate of EP
toxicity test)
n =
                        with A = RT -  x
  df
                                      df =  n  -  1
                 T/2
                                                                          (4)
                                              (5)
                                              (6)
                                                                         (7)
                                      / X.

                                      Arcsin  /p;  if necessary,  refer
                                                 to any  text  on basic
                                                 statistics;  measure-
                                                 ments must be  con-
                                                 verted  to  percentages
                                                 (P)
                                                                         (8)
                                   (9)

                                  (10)

                                  (ID
The upper limit of the CI  for u is  compared  to  the  applicable  regulatory
threshold (RT)  to determine if a solid  waste contains  the  variable  (chemical
contaminant) of concern at a hazardous  level.   The  contaminant of concern  is
not considered  to be present in the waste  at a  hazardous  level  if the  upper
limit of the CI is less than the applicable  RT.   Otherwise,  the opposite con-
clusion is reached.
                                      76

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       TABLE 3-25.   LIST OF INORGANIC  PRIORITY POLLUTANTS (U.S.  EPA 1976
                    Antimony
                    Arsenic
                    Asbestos
                    Beryl 1i urn
                    Cadmium
                    Chromium
                    Copper
                    Cyanide
Lead
Mercury
Nickel
Se1 en i urn
Si Tver
Thai 1 ium
Zinc
ALUMINUM
ANTIMONY
A r CCMT r
rtLoLlNl U
BARIUM
QCDVI 1 T! IM
BtKYLLlUn
BORON
r A PlM T 1 IM
LAUMiUrl
IHKUMIUM
COBALT
pnnn CO
LUrrhK
FLUORINE
LEAD
MAGNESIUM
MA MP A MCC """
MANbANLbc
MCDTf ID V
ntKuUKi
MOLYBDENUM
M T CVC\
ni LIxLL
SELENIUM
C T 1 I/ CD
MLv tK
THALLIUM
TUNCSTEN
VANADIUM
77 fjr
Li IHU
- +
 +
-- +
- -- _ *  - -f-
-f

-r
+
4-- -_  -4.
 r
- +
H 	 +
+
f
> 	 +
' i ,,,,,,..
10        20        30        40
      Number of si tes
                                                           50
                   60
70
Figure 3-13.   Frequency of occurrence of inorganic constituents in soil at FIT
              sites.

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  TABLE 3-26.   PERCENT OCCURRENCE  OF  INORGANICS  IN  SOILSSUPERFUND AND NON-
                    SUPERFUND  SITES  (TOTAL  NUMBER OF  SITES=436)
Pb
As
Cr
Zn
Cd
Cu
15
11
11
9
8
7
Hg
Ni
Ag
Be
Se

6
5
2
2
1

Al
Sb
Ba
B
Co
F
1
1
1
1
1
1
Mo
Tl
W
V


1
1
1
1


along with the  content  of these elements  in  uncontaminated soils, is listed
in Table  3-27.   Barium, boron, cobalt,  and  vanadium concentrations at these
polluted sites were within background  levels.

     Considering inorganics relative  toxicity  (Table 3-25) and their concen-
trations and  frequency of occurrence in present disposal sites, the following
discussion on the behavior of  inorganics  in soils will be limited  to:  As,  Be,
Cd, Cr,  Cu,  Pb, Hg,  Ni, Se,  Ag,  and Zn.   Common  industrial use of  these
elements is listed  in  Table  3-28.

     All  the  elements  under  consideration  are  metals.   Arsenic, selenium,
and chromium  are  the  only metals listed that  can  exist as anions in nature.
Because of their anionic  nature, their  behavior  in soil will differ from  the
other  heavy  metals.    A discussion of  their  unique  behavior will  follow  a
general overview of the  fate of metals  in  soils.

Fate of Metals in Soils

     The  fate  of metals  added  to  soil  will  be  controlled by  a  complex  and
dynamic system of physical,  chemical and  biological  reactions.  Metals, unlike
many hazardous organic constituents, cannot be  readily degraded or detoxified.
Toxic metals  represent   a  long term  threat  in  the soil   environment.   This
threat  can  be  reduced  considerably  if  the  heavy  metals  can  be  permanently
immobilized by either  chemical  or physical methods.

     The heavy metal-soil interaction  is  such  that an  accumulation of metals
normally occurs on the  soil  surface  and downward transport does  not occur  to
any great  extent  unless the buffer capacity of  the soil  is overcome.  Soils
can be  regarded as having  a  finite  loading,  or buffer capacity for metals.
This capacity is  intimately related to  the  solution and surface  chemistry  of
the soil matrix with reference to the  heavy metal  in question.  Because of  the
wide range of soil  characteristics  and  various  forms by  which heavy metals  can
be added to soil, heavy metal  contamination presents a  major problem which  is
highly site-specific.

     A schematic diagram  illustrating  the multiphase equilibria which must  be
considered when defining the soil solution  is  shown  in Figure 3-14.  As Figure
3-14  indicates,  at any  given  time,  heavy  metal concentrations  in  the soil


                                      78

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 TABLE 3-27.   CONTENT  OF  VARIOUS  ELEMENTS  IN  SOILS  (LINDSAY  1979) AND  IN  FIT
                                     SITES
Element
Sb
As
Ba
Be
B
Cd
Cr
Cu
Co
Pb
Hg
Mo
N1
Se
Ag
W
V
Zn
F
Tl
Common Range
for Soils (ppm)
2-10
1-50
100-3,000
0.1-40
2-100
0.01-0.70
1-1,000
2-100
1-40
2-200
0.01-0.3
0.2-5
5-500
0.1-2
0.01-5
NG
20-500
10-300
10-4,000
NG
Average for
Soils (ppm)

5
430
6
10
0.06
100
30
8
10
0.03
2
40
0.3
0.05
NG
100
50
200
0.1
Range found
in FIT sites (ppm)
15d
0.02-11,700
0.02-0.2
2-38
0.3a
0.3-118,300
0.04-136,000
2.2-186,300
2.6^
0.16-466,000
0.04-83,200
322^
0.4-8,800
0.9-1.3
1.2-18
b
0.04-2
0.03-38,000
110,000a
b
aOne site reporting  concentration
    sites reporting  concentration
                TABLE  3-28.   INDUSTRIAL  USE  OF  SELECTED  METALS
As


Be
Cd

Cr

Cu
Pb

Hg

Ni


Se

Ag
Zn
Pesticides, pigments,  glass,  textiles,  wood  preservatives,  fireworks,
printing, tanning,  antifouling paints,  enamels,  ceramics,  lubricating
oil, alloys, oil  cloth,  linoleum,  semiconductors,  photoconductors.
Rocket fuel, alloys, ceramics
Electroplating, pigments,  alloys,  enamels, batteries,  rubber,  plastics,
fungicides, motor oil, textiles
Pigments, chrome  tanning,  electroplating,  chrome-plating,  corrosion
inhibitor, varnishes,  dye  fixers,  photography emulsion,  defolient
Brass, dyes, wire,  fungicides, alloys,  plating,  pipes, roofing,  paints
                   glass,  insecticides, gasoline additive,  ammunition,
                  bronze,  pigments
                   fungicides, pharmaceutical, plastics, paper pro-
                  electrical  apparatus  manufacturing
                  pigments,  cosmetics,  batteries,  electroplating,
Batteries,  paints
solder, brass and
Paints, catalysis
ducts,  batteries,
Steel  and alloys,
electrical  contacts,  gasoline,  spark plugs,  paints,  laquers,  cellulose
compounds
Glass, photocopy,  pigments,  electrical  industry,  paints and  inks,
cosmetics,  paint remover
Photography, electroplating, mirror manufacturing
Alloys, metal coating,  inks, copying paper,  cosmetics,  paints,  rubber
and linoleum, glass     	        	
                                      79

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                                 FREE METAL
                                CONCENTRATION
                                IN SOIL SOLUTION
Figure 3-14.
Principal  controls on  free
solutions  (Mattigod  et  al
Copyright  Notice.
trace  metal  concentrations  in soil
.  1981).   Used  by permission, see
aqueous phase  are governed  by a number  of interrelated  processes,  e.g.,
inorganic  and organic complexation, acid-base reactions,  redox, precipitation/
dissolution,  and  interfacial   interaction.    The ability to  predict  the con-
centration of a given  heavy  metal  in the  soil  solution  depends,  to a large
degree,  on the  accuracy  with which  the multiphase  equilibria  can be calcu-
lated.

     In  terms of industrial spills involving  heavy metals, an obvious strategy
is to  apply  a  treatment(s)  which  will  minimize  the  concentration  of heavy
metal(s) in the soil  solution.   Ideally the  treatment  will  reduce  the metal's
aqueous  concentration to essentially zero,  thus resulting  in  a leakage (leach-
ing)  rate  from  the site to a biologically insignificant level.

     The  soil  chemistry  of heavy  metals  in  soils  can  be  divided  for con-
venience  into  two  interdependent but separate categories:   1)  solution
chemistry and  2)  interfacial chemistry.  Both  are  important in  defining
the  status of  heavy metals  in  soils.   However, since  one  of  the critical
parameters in  evaluating  detoxification  procedures  will be  the  concentra-
tion of a given metal  in solution,  the  topic of  soil  solution chemistry
will  be addressed first.    The  following  brief  discussion  will   be directed
toward  the  general  principles  which  will   affect  the
tation  of  the  solid  phase since  solid  phase  formation
from solution  is a primary  objective of treatment.

Solution Chemistry
                                           di ssolution/precipi-
                                            to  scavenge  metals
     The kinetic aspects of dissolution and precipitation  reactions  involving
heavy metals in the soil matrix suffer from the lack of published data.  Thus
                                     80

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the kinetic component, which in many cases can be critical to decontamination
procedures, cannot be  assessed  easily.   The currently acceptable alternative
is  to  assume  localized  equilibrium  occurs  in the  soil  profile  (Stumm and
Morgan  1981)  and  then  establish  the  boundary conditions  toward  which the
system  is moving.   The application of equilibrium thermodynamics  to the
natural  soil  system  will  not only allow one to predict  if  a given treatment
reaction  is  possible,  but  it will also  provide a  prediction  of the solution
concentration when equilibrium  is  attained.  This  approach  relies heavily on
the accuracy of thermodynamic data that can  be  found  in the literature.


Solid Phase Formation


     Consider the dissolution/precipitation of  a generic solid phase compound
containing a heavy metal  cation  Me and ligand L  in an  aqueous solution

     MejLk = j Mez+ + k l_z-                                               (3-3)

where j  and  k  are  stoichiometric numbers which  numerically  represent the
valence Z of L and Me, respectively.  Assuming constant pressure  and tempera-
ture and ignoring the charge designation  of the ions, the solubility equilib-
rium constant Kso is

     Kso = (Me)J(L)k                                                      (3-4)

where (   )  represent  activities and  the  pure  solid phase MejLk 1S considered
to be at unit activity.  The value of Kso  is related  to the Gibbs free energy
of dissolution by

     AG =  RT In Q/KSO                                                     (3-5)

Where Q,  the reaction quotient,  has the exact  form as Kso (see Equation
3-4) but  represents  the actual  ion activity product  IAP  of Mez+  and Lz~
species in  solution.   When  Q  = Kso the  system  is  at equilibrium  and  AGO;
if  Q/KSO  > 0>  tne solution  is oversaturated  and precipitation  will  occur,
i.e.,AG  > 0  and  Equation  3-3  will  proceed   in  the reverse direction;  if
Q/KSO < 1  tne solution is undersaturated and  dissolution occurs,  i.e.,  AG <
0 and Equation 3-3 proceeds  as written.

     The concept  of  ionic  activity  is   important  in  the development  of any
model of the effect of treatment on heavy metal equilibria.   The relationship
between the  molar concentration  of  the   ith  specie  mj  in  solution  and its
activity is

     i"i  =  ai/mj                                                           (3-6)

where rj  is the  activity coefficient  which has  the  property that  lim  ri = l
as m-j -* 0.   Since natural  systems are   not infinitely  dilute, r-j  cannot  be
assigned  a  value  of  unity.   The  calculation  of  ri  for  an   ionic  specie  of
valence Zj  is  given by the Davies  equation  (Davies 1962)

     -log  ri  = A  Zi?   [(/T/1+7T) -  0.31]                                  (3-7)


                                     81

-------
where I =  1/2  E    m-j  Z   and is summed over  all  charged  species  in solution
               i
and A is the Debye-Huckel  constant which has an approximate value of 0.5 in an
aqueous solution  of a  mixed  electrolyte (Stumm and Morgan 1981).  Equation 3-7
can be used for solution  concentrations of  I <_0.5 ML'l.

     Equation 3-4 can  now be written

     KSO =  CKSO rJ   rk                                                  (3-8)

where cK$o  = m^'  ^  the  1on Product in terms of  molar concentration.   Using
the Davies  equation and rearranging, Equation  3-8 can be written


      P'    =  O     +   1ML~1)  the  possibility exists  that  the
value of  r-j  may become greater than 1 and the  solubility  of  the solid  phase
may decrease in the presence of an inert electrolyte (Stumm and Morgan 1981).

     The  use  of solubility  diagrams  is  a convenient  technique  of showing
how the solubility  of heavy metals  compounds  varies with  pH  and  at  the same
time it allows  some prediction as to what  solid  phase  regulates heavy metal
activity in  the soil  solution.  An example is the  solubility diagram for lead
in soils  (Lindsay  1979)  which shows the  relative  solubilities of lead  sili-
cate, phosphate, and carbonate as predicted  in pure water  in equilibrium with
atmospheric  C02-   This is  shown  in  Figure 3-15  which  also incorporates  the
solubility  isotherm  for tricalcium  phosphate (TCP), dicalcium phosphate
dihydrate  (OCPD),  and  hydroxyapatite  (HA).    The  solubility  data  presented
supports  the  idea  that  soil  phosphorus  may be  a  factor  in  regulating Pb2+
ion activity as originally suggested by Nriagu (1974).

     Santill an-Medrano and Jurinak (1975)  obtained  experimental data  from soil
column studies using both  Pb and  Cd .   The  data in  Figure 3-16 show that  in the
calcareous  Nibley  soil:    1)  the  solubility of  Pb decreases  with increasing
soil   pH,  which  is  the usual  trend  for  most  heavy metals,  2)  Pb  phosphate
compounds could be regulating  the activity  of Pb++  ion in solution,  and
3) mix compound  precipitation  cannot  be  precluded between  pH 7.5-8.0 because
of the convergence of  the  solubility isotherms for  PbC03,  Pb(OH)2, Pb3(P04)2,
and  Pb5(PC>4)3  Cl.   Similar comments  can be made  for  the  solubility  of  Cd in
Nibley soil   (Figure  3-17)  with  the  additional  comment that the solubility of
Cd is considerably  higher than Pb  at any  pH  and  at  the high  pH  values the soil
solution is  undersaturated with respect to the compounds considered.

Heavy Metal  Complexation in Soil  Solution

     Heavy  metal  ions form  many  soluble complexes with both organic  and
inorganic ligands.    The  effect of  complexation  is  to increase  the solubility


                                      82

-------
Figure 3-15.   The solubility of vairous lead oxides,  carbonates,  and  sulfates
              when  S0|~  and  CT  are 10~3 M and  CC>2 is  0.003 atm or as
              specified  (Lindsay  1979).    Used by  permission, see  Copyright
              Notice.
Figure 3-16.   The solubility diagram  for Pb  in  Nibley  clay  loam  soil  (San-
              til 1an-Medrano and  Jurinak  1975).   Used  by permission, see Copy-
              right  Notice.
                                      83

-------
                   u
                  a
                   a.
                   10
                    6.0
                          6.5
                                 7.0
                                       7.5

                                       PH
                                            8.0
                                                   8.5
                                                         9.0
Figure 3-17.
              The  solubility  diagram for  Cd  in Nibley  clay  loam soil  (San-
              til 1an-Medrano  and Jurinak 1975).   Used by permission, see
              Copyright Notice.
of the solid phase of  which  the  complex  ions  are constituent.   At any time,
the total concentration of metal  Mej  in  the  soil  solution is the sum of the
free  ion  concentration  [Me^"1"] and the  concentrations of  all  organic and
inorganic metal  complexes.  A general expression considering complex formation
with any type of  ligand  L or its protinated  form HXL plus  hydroxo complexes
is given  (Stumm  and Morgan 1981)
     Mej =
                       Z[Mem Hk Ln (OH),-]
where m,  n,  i  or K >_ 0.
complex  designation.
                           In Equation  3-10 ion  pairs are included in the
     The dominant  complex  specie  in  the  soil  solution  can  be  significant when
dealing with the  transport  of heavy metal through  the  matrix.   The  factors
involved  are:   1) the  free metal  concentration,  2) the dominant  complex
specie, and 3)  the charge  on the  complexes.   Inorganic complexes  which can  be
expected to be  formed with bivalent metals are given in Table  3-29.

     Doner  (1978), using soil  columns,  studied  Cd, Cu, and Ni  transport
as affected  by Cl~ and  C104~ ions.   This study  clearly  showed the  effect
of the  chloride complex on  heavy metal  movement in soils.   The  breakthrough
curves for  the three metals  are  shown  in  Figures 3-18,  3-19, and 3-20.  The
mobilities were found to  be in  order with the  dissociation  constants  of the
chloro-complexes of the  metal  ions,  i.e., Cd > Cu > Ni.

     An example of how complexation  affects solubility is shown  in Figure 3-21
where the  solubility of CuO is plotted  as a  function of (H+).   The  observed
solubility,  in the pH  range  of  most natural  systems,  is  attributed  to the
Cu2+  ion and the two carbonate complexes.
                                     84

-------
      TABLE 3-29.  SOME PROBABLE BIVALENT METAL COMPLEXES  WITH  INORGANIC
            LIGANDS  IN SOIL SOLUTIONS  (FROM MATTIGOD  ET AL.  1981)
                  Used by permission,  see Copyright Notice.
OH
MOH+
M(OH)2
M(OH)3~
M(OH)42-
CL
MCL+
MCL2
MCL3-
MCL42-
S04
MHS04+
MS040
M(S04)22-

C03
MHC03+
M(HC03)2
MC03
M(C03)22-
P04
MH2P04+
MHP040
MP04"

           o
           o
               I Or
              0.8
              06
              0.4
              0.2
                                      NoCI04
/i*0!M
  000009M
                       100     200    300     0       100

                              PORE VOLUME  NUMBER
                          200
Figure 3-18.   Breakthrough curves  for Cd  as  affected  by  Cl~  and  C104-  ions
              (Doner 1978).  Used by permission, see Copyright  Notice.
                                      85

-------
              o

             *
             o
                 10
                06
                06
                04
                0.2
                                 NaCls
                                                    i J
                        100    200    300     0      100    200


                                 PORE  VOLUME NUMBER
300
Figure 3-19.   Breakthrough curves  for  Cu  as  affected by  Cl" and  C104" ions

              (Doner 1978).   Used by permission, see Copyright Notice.
              o
              o
                 1.0
                 0.8
                 06
                 04
                 0.2
                   0      100    200     300      0      100     200


                              PORE  VOLUME  NUMBER




Figure 3-20.  Breakthrough  curves  for Ni  as affected  by  Cl~  ar.d  C104~  ions

              (Doner 1978).  Used by permission, see Copyright  Notice.
                                      86

-------
                  Or-
Figure 3-21.
                                      -log{H*}
Solubility of CuO as a  function  of  log  {H+}  (25C.,  I = 0, log
PC02 = -3-52) (Schindler 1967).   Used  by permission,  see Copy-

Right Notice.
     Organic complexation  of  heavy  metals  in  soil  is  not  as well  defined
as  inorganic  complexation  because  of  the  difficulties  of   identifying  the
organic ligands.   The recent disposal technique  of land application of sewage
sludge  has  fostered  considerable  interest  in  heavy  metal   complexation  by
fulvic acid extracted from  sludge (Sposito et al .  1977,  1979, 1981;  Behel  et
al.  1983, and  Baham  and  Sposito  1983).

     Sposito and  co-workers have  developed  an  interesting  conceptual  fulvic
acid model to interpret potentiometric titration data involving heavy metals.
In  brief,  a fulvic  acid  extract  is  treated  as an  assembly  of hypothetical
macro molecules (similar to protein molecules).    This  system  has  been deter-
mined to contain  four classes  of acidic  functional groups which can react with
heavy metals through  proton exchange  (Sposito and  Holtzclaw  1977).   Of these
four groups, only two appear to  be important in  complexing the metals studied.
Table  3-30 gives experimental and  estimated  values of cKi for i  =  1,  2.
These  studies were  conducted  in an ionic medium of 0.1M  KC104-    KI  and
l<2  refer to the  stability constants of the two functional groups  of  the
fulvic  acid model.    It  is of  interest  to  note tnat  log CK
to the log K values  for  metal  complexes  with alphatic acids such
acetic (Martell  and  Smith  1977).
                                                 are  comparable
                                                   as  citric and
Computer Simulation of the  Soil  Solution

     The multiphase  eauilibria  and  the myriad of potential interactions
involving heavy metals make the  soil  solution  a prime candidate for computer
simulation,   however,  because  of the limitations  in  analytical  techniques, the
                                      87

-------
             TABLE 3-30.  ESTIMATED VALUES OF LOG CKX AND LOG
                      (MODIFIED FROM SPOSITO ET AL.  1981)
                   Used by permission, see Copright Notice
       Metal  cation                     logcKi                   1ogcl<2
Mg2+ 2.71
Ca2+ (3.12)a
Mn2+ 3.93
Fe2+ 3.96
Ni2+ 3.81
Cu2+ (3.88)
Zn2+ 3.54
Cd2+ (3.04)
Pb2+ (4.22)
0.69
1.23
2.23
2.28
2.08
(2.11)
1.74
(2.27)
(2.62)
aParentheses denote  measured values.
complete validation  of  the  free  ion and metal complex concentrations predicted
is difficult.

     An excellent example of an equilibrium model which  has  been  used  exten-
sively in soil chemistry is  GEOCHEM.   This  model  (Mattigod  and  Sposito 1979)
was  developed  from  the  program REDEQL2  (McDuff  and  Morel  1974).   GEOCHEM
expands REDEQL2 to account  for ion exchange  and expands the  base for equilib-
rium constants particularly with regards to  inorganic and  organic metal
complexes.

Sol id-aqueous  Interface Exchange
(Outer Sphere  Complexes)"

     As cations, metals  are capable of participating  in  cation exchange
reactions on  negatively charged surfaces of  layer  silicates  (clays),  oxides,
and  organic matter.    Negatively charged mineral  surfaces arise  from  either
substitution of structural  cations by  ions of lower charge (permanent negative
charge) or  by dissociation of  hydrogen  ions  of surface  edges  (pH-dependent
charge).  The negative charge of organic matter is  totally  pH  dependent and
arises from the  dissociation of functional  groups.   Cations  are held loosely
in  the vicinity  of these  negative  charged sites  by  electrostatic  forces.


                                      88

-------
These sites  are  "non-specific"  (outer sphere complexes)  and  cations  held at
these sites can be displaced  by  other  cations.

Specific Adsorption (Inner Sphere  Complexes)

     Specific  adsorption  forming  inner  sphere  complexes  at  the  interface
is  distinguished  from  the  exchangeable  state  in  terms  of  the  increase in
binding energy  between  the metal and  the surface.  Metals specifically
adsorbed are  apparently held by  electrical  forces  as  well  as by additional
forces  including  covalent  bonding,  Van der  Waals forces,  and steric fit
at  the  site.  The  term specific implies that  other  metal  cations  do not
effectively compete for the  surface site occupied by the specifically adsorbed
metal cation.   This  is the  practical  distinction  between the  non  specific
exchangeable and  specifically adsorbed  states.

     Specific  adsorption  is  the  most  important  interfacial   mechanism  con-
trolling soil-water concentration  of a particular metal  ion at low concentra-
tions.   As more of this metal ion  is  added,  a specific  adsorption capacity or
limit is apparently reached  and  additional metal ions enter  less energetically
bound exchange  positions.    Specifically  adsorbed  metals  are relatively im-
mobile   and  unaffected  by  moderate concentrations  of  "macro"  salt  cations,
i.e., Ca, Mg, Na and K.  Metals held by exchange mechanisms will, however, be
subject  to  exchange  and  subsequent  leaching  as  "macro"  cation concentrations
increase.

     The sorption capacity (exchange and  adsorption)  of a soil is determined
by  the  number and  kinds  of  sites  available.    Sorption  of  metals  has  been
correlated with such soil  properties as clay content, soil organic matter, Fe
and  Mn  oxides and  calcium  carbonate,  all of  which  contribute to the soils
cation  adsorption potential.   Sorption  processes are affected  by these various
soil factors, by  the form  of  the metal  added, and by the nature of the solvent
introduced  along  with  the metal.   The result  of these  interactions  may in-
crease  or decrease the movement  of heavy metals with the soil  water.

Factors  Affecting Sorption

Effect  of An ions--
     Metal  cations will form ion-pairs, complexes and chelates with inorganic
and organic anions.   Anionic  ligands form metal associations that have a lower
positive charge than the  "free" metal  cation.   The  resulting  association may
be uncharged or it may have a net  negative charge.  Benjamin and Leckie (1982)
stated   that  the   interaction  between  metal   ions  and  complexing  ligands  may
result  in either  a  complex that  is weakly sorbed  to  sorbent surfaces  or  in a
complex  that is sorb more  strongly than the "free" metal  ion.   In general, the
decrease  in  positive  charge  on  the  complexed  metal reduces sorption  to  a
negatively charged surface.   One noted exception  is  the  preferential  sorption
of  hydrolyzed  metals  (MeOH+)  versus   the  "free"  bivalent  metal   (James  and
Healy 1972).

     Within normal concentration  of electrolytes  in  soil  solution,  Elrashidi
and O'Connor  (1982)  found  no measurable  changes in Zn  sorption  by soils due
to complex  formation  of  Zn  with  Cl", NC'32", or  SO^-  ions.  Under these


                                     89

-------
conditions,  anion complex formation did not compete with the highly  selective
sorption sites for Zn.   The highest anion concentration  studied was  0.1 ML~1.

     Doner  (1978) using  0.1 to  0.5 M NaCl  leaching  solutions,  concluded
that  the  increased  mobility,  relative to  NaC104  leachate,  of  Ni,  Cu,   and
Cd  through  a soil  column was  due to  complex  formation of the  metals with
Cl~.  The mobility  of  Cd  increased more than  that of Ni and Cu,  Ni  being  the
least mobile.  These observed mobilities are in the  same order  as that  of  the
stability constants  of  the  chloride complexes of  these metals (Table  3-31).
Complex ion  formations  may be represented by the equation:

     Me2+ +  nCT = MeCln2-n                                              (3-11)

where n  is  the  number  of Cl~  ions complexed  with  the  metal  ion, Me2+.   The
stability constant,  K,  is defined  as:

     K = (MeC1n(2-n)/(Me2+)  (CT)n                                      (3-12)

where (    )  denotes activity.   The  larger the  log K  value, the more  stable
the  complex.   Doner et  al.  (1982),  using  geothermal  brine solutions, again
found increased mobility  of  Cu,  Pb, Zn, and Cd due to  complex  formation with
Cl~.   Mercuric-chloride  complexes  are not as  strongly adsorbed as the  Cl~
free species (Kinniburgh  and Jackson  1978).  The  effect  is  pH-dependent, with
the  greatest  complexing  of  Cl~  and Hg(II) at  low pH  (4.5).   These  authors
caution  against  generalization regarding   Cl~  inhibitory effect  on  sorption
of other metal complexes.

     Complex  formation  between metals  and organic  ligands may   also  affect
metal sorption  and  hence mobility.   This complexation  may be of  particular
importance  when  organic  waste  is involved at the same spill  site.   Bowman
et al. (1981) demonstrated drastic reduction in Ni sorption  in  the presence of
EDTA, a  synthetic chelating  agent.   Elrashidi and  O'Connor (1982)  likewise
found that  EDTA  and  DTPA can compete effectively  with  the  soil sorbing sites
for  Zn.   Both  papers emphasize the great potential for  leaching  of  metals in
the  presence of organic ligands.

     Application of organic matter to  soils, e.g.  sludge, may,  in some  cases,
increase the mobility  of  metals if this material   contains  significant  levels
of  dissolved  organic matter.   The fulvic acid fraction  of sludges has been
shown to complex metals (Sposito et al . 1979;  Sposito et al. 1981; Boyd  et  al.
1979; Sposito et al. 1982).   Fulvic acid is soluble between  pH  1 to 11 (Holtz-
claw et al.  1976).  Baham's  et al. (1978)  study illustrated  the relative order
of affinity of fulvic acid fraction of sludge  for  metals: Cu >_ Fe >  Zn  >^ Ni >
Cd.   Stability constants  of metal  organic  complexes  may govern  their relative
mobilities.    Increased mobility  of metals  in  a  sandy  soil  and  a sandy  loam
soil with the addition of sludge  was  also  observed by Gerritse et al .  (1982).
The  authors attributed this  increase not  only to complexation  by  dissolved
organic  compounds,  but  also to  high  ionic  strength  of the   soil  solution.
Khan  et  al. (1982)  showed that  the mobility  of metals  through soil followed
the  order:   Cu  >  Ni > Pb >  Ag > Cd.  The high  mobility of  Cu and  Ni  was
attributed  to their  high complexing nature with  soluble soil  organic  matter.
Overcash and  Pal  (1979)  reported  that  the order  metal-chelate  stabilities is
Hg > Cu > Ni > Pb > Co  >  Zn  > Cd.


                                      90

-------
     TABLE 3-31.   STABILITY CONSTANTS  FOR  Cl  COMPLEXES TO Ni(II), Cu(II),
                   AND Cd(II).   FROM MATTIGOD ET AL.  (1981)
                   Used by permission,  see Copyright  Notice
                  Metal              Stability constant, log
                  Ni(II)                     -0.43
                  Cu(II)                     0.40
                  Cd(II)                     1.98
     The extent of  complexation  between  a metal  and  soluble organic matter,
and hence mobility, depends  on  the competition between metal-binding surface
sites and the organic  ligand  for the metal.   Metals with a high affinity for
organic chelates,  such as Cu and Ni, will readily be complexed by the organic
matter and will  be subject to leaching.  Metals such as  Cd and Zn that do not
form highly stable complexes with organic matter will be less affected by its
presence in the  soil  solution.   Elliott and  Denneny (1982)  stated  that soil
metal  binding sites  should outcompete organic  ligands  for Cd if  the log
stability constant  for  the  metal-organic  complex  is  less  than six (Table
3-32).   Their study  showed  that  only NTA and  EDTA. reduced Cd  sorption  by
soil .

Effect of pH on  Sorption--
     Most fuctional  groups of chelates,  as well  as  most complex and  ion-pair
formers are weak acids,  thus  the stability of the metal complex is  pH depen-
dent with  little  association in acid  media.   The degree  of association in-
reases with pH  to a  maximum  often determined by  some  competing alternative
reaction such as  precipitation.    Elliott  and Denneny's (1982)  study illus-
trated this effect of  soil  solution  pH on  organic ligands.   As  soil  solution
became  increasing  acidic, the  influence of the organic  ligands  (Ox)  on
metal   sorption diminished  (Figure  3-22)  due  to  a decreasing ability of the
ligands to  bind the metal  relative to H+.   As the  pH  increases,  the concen-
tration of  metal-ligand  complex  again  decreases  due to  the  hydrolysis  of  Cd
(CdOH+, CdOH2)  at pH>8.

     pH also  directly effects sorption  (McBride  and  Blasiak  1979,  Kuo and
Baker  1980, Harter 1983).  Many  sorption sites in soil  are  pH  dependent
so that as  the pH decreases,  the number  of possible negatively charged sites
diminishes.    In acid  media,  metals face competition  for available  permanent
charged sites by  H+ and  Al3+.   Figure 3-23  shows  the  impact of soil  pH  on
Cd sorption by three soils.   As  is true  for  all  cationic metals,  Cd sorption
increased with pH.

     Cavallaro and  McBride (1980)  found  that  soils of  higher pH  retain  more
Cd and Cu.   Copper  sorption showed  a  stronger pH dependence than  Cd.   This
finding  is  consistent  with the hypothesis  that  hydrolysis  of Cu  at  pH  6
increases  its  retention by soil.   Cadmium does not hydrolyze until  pH 8  (see


                                     91

-------
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           .6
         o>
         o> ,
         E '
        I'4

        2.3

        O
        ffi
                          2x I0"3 M CaCI2

                             Soil 3- silt  loam, pH 5.2

                           a  Soil 4-silt  loam, pH 4.4
                           A  Soil 5- sandy, pH 4.5
            5.0  5.2  5.4  5.6  5.8  6.0 6.2  6.4  6.6  6.8  7.0  7.2   7.4
Figure 3-23.
Cadmium binding as a function of pH (Tirsch et al.  1979).   Used
by permission,  see Copyright Notice.

Note:    The  sandy textured  soil,  #5,  sorbed the least  Cd  over
this pH range.   Differences in sorption of  Cd  between  soils 3
and 4 may be due to the  higher oraanic  matter  content  in  soil
4.
Figure 3-22).   Table 3-33 shows  the  predicted percent distribution  of  metal
species with  pH  (Harter 1983).   The  increasing importance of  the  hydrolyzed
metal species with pH should  effect metal  sorption.

     Jenne (1968)  stated  that  hydrous  oxides  of Fe  and  Mn play a  principal
role  in  the  retention  of  metals  in  soils.    Solubility  of Fe and  Mn  oxides
is  pH-related.   Below pH  6, the oxides of  Fe and  Mn  dissolve  releasing
sorbed metals ions to solution (Essen  and  El  Bassam  1981).

Effect of Other Cations Present in Solution--
     For  specific  adsorption  sites,  heavy metals are  preferentially adsorbed
over  alkaline  metals  (Na, K,  Ca, Mg)  (Milberg et  al .  1978;  Kinniburgh  and
Jackson  1982).    However,  when  specific  adsorptions sites become  saturated,
exchange reactions dominate and  competition  for  these  sites with  soil "macro"
cations become important.   Cavallaro  and McBride (1978)  found  that sorption of
Cu  and  Cd decreased  in the  presence  of  0.01M  CaCl2.   They  attributed this
decrease, not to complexation with Cl, but to competition  with Ca  for sorption
sites  (Figure  3-24).   Cadmium  sorption  (not shown) was more  affected  by the
presence Ca  than  was  Cu.   The mobility of Cd  may be greatly  increased  due to
such competitions.   Likewise,  Harter  (1979)  indicated the  Ca  in  solution had
a greater affect on Pb sorption than  on Cu.

-------
      TABLE  3-33.   EFFECT OF pH ON PROBABLE SOLUTION  PERCENT COMPOSITION
                OF  DIFFERENT ION SPECIES3 (FROM HARTER  1983)
                 Used by permission, see Copyright Notice
              PH
5
Pb2-
PbOH"
Pb(OH)20
CU2-
CuOH-
Cu(OH)20
CuCOpO
Zn2-
ZnOH-
Zn[OH)2
Ni2"
NiOH-
100

100

100


100

100

100

100


100

98
2
96
2
2
98
2

100

83
17
1
33
7
56
4
83
17

100

33
66
1
1
92
6
31
64
5
99
1
-ihe  solution  is  assumed to be in equilibrium with  atmospheric C02
 and  it  is  further assumed that anions other than OH~,  HC03",  and
 C03=, are  not  present in large enough quantities to  make a contribu-
 tion  to  solution complexes of these metals.
                       2.0-
                       10-

                       s,

                       .2
                               o Lansing A (neutral soil pH)
                               D Lansing A in .01 M CaCI2
                               i Mardin A          .. (acid soil pH)
                                Mardin A in .01 M CaCI;,
 ;gure 3-24.   Cu^+ adsorption  isotherms  on Lansing  and  Mardin A horizon soils;
              in  the absence  and  presence of  0.01M  CaClz  (Cavallaro  and
              McBride 1978).    (Note:   under the  same  conditions  the neutral
              Lansing A  soil  sorbed  more Cu+2 than the  acid  Mardin A soil.)
              Used by permission, see  Copyright  Notice.
                                       94

-------
"'x id at ion-reduction

     The metals  under  discussion at  the  present time,  Cd,  Zn, Pb,  Ni,  and
lu,  normally  have  one oxidation  state  in the  soil  environment and  are  not
:irectly affected  by  changes  in the oxidation-reduction  (redox)  potential
in soils.   The redox  potential  does affect  the solid  phase of soils,  in
oarticular  Fe and Mn  oxides.   Under reduced  conditions  Fe  and Mn  oxides
are  solubilized,  releasing  associated  heavy metals.   Sims and Patrick (1978),
nowever, found that  Zn  and  Cu did  not  remain in  solution but became associated
with exchange  and organic sorption sites.   The solubility  and decomposition of
organic matter is also  affected by soil redox.

      Mercury, As,   Se  and   Cr  all  have multiple oxidation  states  in soils.
Their  reaction in  soil  is  directly dependent  on  the  redox potential  of
-he soil.   (This subject  will  be  discussed  in greater detail in  a  later
section.)

Adsorption  Isotherms--
     Langmuir   and  Freundlich equations have  become  popular  as  a  means  of
describing  solid-solution  reactions  in  soils.    The  Langmuir expression pro-
vides  a theoretical  adsorption maximum and  a coefficient which  is theoretical-
ly related  to  bonding  energy.  The linearized form of the  Langmuir equation:
                           1
      x/m    (x/m)max    (x/m)max b
                                                                       (3-13)
Miere C  is. the  concentration or activity of the  free  metal  in solution, x/m
is the  quantity  (meq/100  g)  of the metal ion  adsorbed  by the soil, (x/m)max
is the  maximum  adsorption capacity  of  the  soil, and  b is  the  coefficient
-elated to bonding energy.  When  is  plotted as a function  of C, the  slope
                                 A / lit
vi 11  be the reciprocal  of  the adsorption  capacity,  (x/m)max, and the intercept

vi 11  be-;r-r	r-.   A  typical  linear Langmuir  adsorption  isotherm is given in
        \ x/m)max  o
rigure 3-25.

     The Freundlich  expression is essentially empirical  but  has the virtue of
oeing of  appropriate  form to  fit  the  graphical   shape  (Figure 3-26)  of many
-netal sorption data.  The linearized form of the  Freundlich isotherm equation
's:

     log (x/m)  =  1/nlog  C  + log K                   '                     (3-14)

vnere x/m  and  C  have defined  previously and  1/n  and  K  are  constants  fitted
rom  the experimental data.   A typical  Freundlich  adsorption isotherm is  given
:n Figure 3-27.   The two  sections of this plot, the linear form of the Freund-
"ich  equation followed  by the  curvilinear  section,  has  been  interpreted  to
'ndicate two different  mechanisms of retention  of  Ni by this soil.

     Cavallaro and  McBride   (1978)  used  the Langmuir  expression  to describe
sorption of Cu and  Cd  by  two soils.   Table  3-24  gives values  for the Tiaximum

                                     95

-------
                                          8    10

                                            (M)
Figure 3-25.  Langmuir adsorption  isotherm for Cu^"1" adsorption  on  the Lansing
             A soil (Cavallaro  and McBride 1978).  Used by permission, see
             Copyright Notice.
               o>
                  EQUILIBRIUM  SOLUTION CONCENTRATION
                                    meq/l
Figure 3-26.   Typical adsorption isotherm  fcr metals and soil
                                     96

-------
                    s
                    ^
                    X
                      -2
                         GLENOAtE CLAY
                           -4   -3   -2-10    I

                                   LOG ACTIVITY (PPM)
Figure 3-27.  Nickel sorption  by  Glendale soil, 0.01N CaCL2.
       TABLE 3-34.  CALCULATED  LANGMUIR PARAMETERS FROM SOIL ADSORPTION

             OF Cu2+ AND Cd2+  (FROM  CAVALLARO AND MCBRIDE 1978)

                  Used by permission,  see Copyright Notice
(x/m)max(meq/100 9)

Lansing A-Cu2+
Lansing A-Cd2+
Lansing C-Cd2+
Mardin A-Cu2+
Mardin A-Cd2+
No
Salt
5.6 + 0.4
4.0 +_ 0.5
4.1 +_ 0.8
2.3 + 0.2
1.1 T 0.1
0.01 M
CaCl2
2.2 + 0.2
0.2 + 0.05
1.2 +_ 0.1
0.6 + 0.1
070
bxlO-5 (M-l) r2
No
Salt
15.6
1.7
1.3
1.5
1.9
0.01 M
CaCl2
3.2
^0.2
2.3
0.5
a
No
Salt
0.99
0.97
0.95
0.99
0.99
0.01 M
CaCl2
0.99
a
0.99
0.94
a
aAdsorption was too low to  permit  calculation.
                                       97

-------
adsorption  capacity  ((x/m)max)  and for  the "bonding constant"  (b).  The
authors determined that the sorption maximum for Cu2+ was  slightly  less  than
the CEC  of  the Lansing  A soil (neutral  soil pH),  while the  maximum  Cu^+
adsorbed  by Mardin  soil  (acid soil  pH)  was less  than  half  the  soil's  CEC.
This indicates  that  Cu  was  not  held as  strongly  on the  Mardin  soil.   The
adsorption  maximum for  Cd  was less  than  Cu.   The bonding constant  (b)  re-
flected  the weaker  retention  of  Cd relative  to  Cu in  the  Lansing  A  soil,
although  this  effect  is  not  consistent  for Mardin A soil.  The  presence  of
0.01M  CaCl2  lowered  the values of  (x/m)max and  b  by  introducing  Ca^+  ions
competition  for exchange  sites.

     Bowman  et al. (1981), using  K values derived from  the  Freundlich  equa-
tion,  compared the sorbing tendencies of  11 soils  for  Ni  (Table  3-35).   The
Tuff sample  (unweathered  rock)  showed much  lower  affinity for  Ni  than  did the
soils  studied.   Table  3-36  (Bowman et al. 1981) illustrates  that  the  effect  of
Ca  concentration  and  the  effect  of anions,  Cl~  and C104"  on  the  sorption
resulted  in  a lowering  of  sorption.   Sorption   in  the non-complexing  per-
chlorate  (C104-)  system  was  greater than  in  the  0.1N  CaCl2  system,  but  was
much less than  that  in the 0.01N CaCl2  system.   The authors concluded  that
Ca  competition for sorbing sites,  rather  than Cl~ complex formation,  played
the greater  role  in reducing  Ni sorption.

     Elrashidi  and O'Connor (1982) compared the affinity of  Zn  on nine soils
(Table  3-37) using Freundlich parameters.   The  authors  also used  these param-
eters   in  a  correlation  of  sorption affinity  with  various soil  properties.
Clay percent,  CEC,  and specific   surface were  all  found to  be  significantly
correlated to  Zn  sorption.

     From the  above  examples  it   is evident  that the  mathematical  form  of
the Langmuir  and Freundlich  isotherm  expressions,  have  proven  valuable  in
interpreting metal behavior  in  soils.    At present,  however,  the  applica-
bility  of adsorption  isotherm equations to the  interpretation  of  soil chemical
phenomena is a  subject  of controversy.   For further discussion of  this  con-
troversy  see  Elprince and  Sposito (1981); Griffin  and Au  1977;  Veith  and
Sposito 1977;  and  Sposito  (1979).

     The  preceding discussion  dealt with  the general  behavior  of  divalent
heavy  metals  in  the  soil  environment.   Although principles  of sorption,
precipitation,  etc.,   are  applicable to the  fate  of all  ions  in soil,  some
specific aspects of  the chemistry of  As, Se,  Hg,  Cr, Ag,  and  Be must  be
discussed individually.

Anions  in the  Soil Environment--
     Of  the metals under consideration  in  this  text,  arsenic,  selenium
and chromium,  in one  of  its  oxidation  states,  exists  as anions  in  soils.
Like cationic  metals,  these  anions will   participate  in  precipitation  and
sorption  reactions.

     Soil particles,  though  predominantly  negatively charged,  may  also
carry  some  positive charges.   The oxide surfaces, notably iron  and aluminum
hydrous-oxides, can generate  a significant number  of positive charges as the
pH  decreases.   For example,  at pH 8-8.5  the positive and negative changes  on
                                     98

-------
TABLE 3-35.   FREUNDLICH PARAMETERS AND CORRELATION COEFFICIENTS FOR SORPTION
              OF Ni IN 0.01N CaC12 BY 12 SOILS.   DATA FOR INITIAL
              NI CONCENTRATIONS OF 100 AND 1,000 ppm OMITTED (FROM
                              BOWMAN ET AL.  1981)
                   Used by permission, see Copyright Notice
         Soil
1/n
Car jo
Puye
Tuff
Chem Bottom
R-28
R-30
Glendale
Reagen
Palouse
Doak
Harvey
Lea
262
74.0
8.23
517
534
380
650
541
396
199
233
441
0.95
0.87
0.92
1.18
1.02
1.01
1.03
1.02
0.96
0.99
0.97
0.97
0.999
0.993
0.997
0.999
1.000
0.999
0.998
0.999
0.999
0.999
0.997
0.998
 TABLE 3-36.   FREUNDLICH PARAMETERS FOR SORPTION OF Ni IN DIFFERENT Ca SOLU-
                  TIONS BY FOUR SOILS.   DATA FOR INITIAL Ni
                     CONCENTRATIONS OF  100 AND 1,000 ppm
                      OMITTED (FROM BOWMAN ET AL.  1981)
                   Used by permission,  see Copyright Notice
Matrix
Soil
Carjo
Glendale
Doak
Tuff
0.01N
K
262
650
199
8.23
uc,2
1/n
0.95
1.03
0.99
0.92
0.1
K
43.8
534
78.2
3.45
CaCl2
1/n
0.91
0.95
0.81
0.87
0.1N
K
70.2
691
98.6
5.05
Ca(C104)2
1/n
0.94
0.98
0.85
0.87
                                      99

-------
 TABLE 3-37.   FREUNDLICH PARAMETERS  FOR  SORPTION  OF  ZN  IN 0.01N CACL2 BY
                     THE SOILS STUDIED*   (FROM  ELRASHIDI AND
                                O'CONNOR (1982))
                     Used  by permission,  see Copyright  Notice
                                        Freundlich  parameters
       Soil
                                     Part  lb
                                        Part 2b
                           1/n
1/n
Car jo silt loam
Puye sandy loam
Tuff loamy sand
Chem B sand
R28 sand
Gl end ale clay
Reagan clay loam
Lea sandy loam
Harvey sandy loam
134
61.0
29.2
1434
829
2732
808
1318
557
0.84
0.88
0.84
1.04
0.91
0.94
0.97
1.03
0.97
92.8
29.9
17.2
108
102
469
302
293
189
0.47
0.52
0.45
0.42
0.44
0.44
0.53
0.46
0.41
Correlation coefficients  for  all  Freundlich  adsorption equations are
 > 0.98.
bParts 1 and 2 refer  to  linear isotherms  at  low  and  high Zn  solution
 concentrations,  respectively.
the surface of goethite  (FeOOH)  are  balanced  and the surface exhibits no net
charge.  This pH  region  is  known as the zero  point  of  charge (pzc).  At pHs
above the pzc the goethite surface will have a net negative charge and at pHs
below  the  pzc  the  surface  will  have  a net  positive  charge  (Figure 3-28).
Oxides can  differ widely in  their pzc.

     It has  also  been suggested  (Van  Olphen  1963) that  broken  bonds at the
edges  of the  particles of  clay minerals,  particularly  of  kaolin types, may
carry localized  positive  charges.   This might be  expected, particularly at low
pH values.

     Clay minerals and  oxides  exert a strong  preference for  some an ions
in comparison to other  anions,  indicating the  existence of  chemical   bonds
between the  solid surface  and  the specific anion.   Phosphate  has  been the
most  extensively studied  anion  that exhibits this specific sorption phenomena.
Phosphate ions are bonded strongly,  or  "fixed,"  by clay minerals and oxides.
The sorption capacity for phosphate  and  other  anions is, however, very  small
relative to cation sorption  capacity of soils.
     ChromiumChromium
             -3+
forms, the  Cr-
       exists  in four  possible  forms   in  soils--trivalent
cation and  the  CrO?"  anion  and hexavalent  forms,
                                      100

-------
                     FeOHr
                   71
                     FeOHt*
                   -71
                surface acid side of p.z.c.
                                     _FeOH"

                                        p.z.c.
FeOH:'
                                                   /Fe-OH-


                                                   alkaline side of p.z.c.
Figure 3-28.
              Zero point of charge  (pzc)  on an iron hydrous  oxide  (Greenland
              and  Hayes  1981).    Used  by  permission,  see copyright  notice.
and
potential
           .   Figure 3-29  illustrates  the relationships between  pH and redox
          and speciation of chromium in water.
     Hexavalent  chromium  is  the  major  chromium  species  used  in  industry.
Forms of  Cr(VI)  in soils  are  as chromate  ions  CrO^-,  predominant  at  pH 6,
and  as  dichromate  ions  C^Oy2", predominant  at  pH 2-6  (Figure 3-29).   The
dichromate  ions  possess  a greater  health  hazard than  chromate ions.   Both
Cr(VI) ions are more toxic than Cr(III) ions.

     Because  of  Cr(VI)  anionic  nature,  its  association  with  soil  surface
is limited to positively charged exchange sites,  the number of which decreases
with  increasing  soil  pH (Figure  3-30,  Bloomfield and Pruden  1980:  James and
Bartlett 1983).  No precipitates  of  any hexavalent  compounds  of chromium were
observed in the pH  range  1.0 to 9.0  (Griffin  and  Shimp 1978).  Thus Cr(VI) is
highly mobile in  soil.

     Chromium (III)  is  considered the  stable  form  of chromium  in  soil.   The
predominant  cationic  form  of   Cr(III)  in  aqueous  solution  is  [Cr(H20)s]3+.
Increasing pH  results  in the  formation  of  hydroxy species such as Cr(OH)2+,
Cr(OH)2+,   ...   Cr6(OH)126+.   All species  of Cr(III)  are readily  sorbed by
soils.   In a study of the  relative mobility of metals  in  soils of  pH 5,
Cr(III)  was  found  to be the least mobile (Griffin  and Shimp  1978).   Hydroxy
species  of Cr(III)  precipitate  at  pH 4.5.   Complete  precipitation  of the
hydroxy species occurs at pH 5.5 (Figure 3-31).

     At  most soils' pH  and redox, Cr(VI)  is reduced  to Cr(III).  Soil organic
matter and reduced  Fe can  serve  as electron donors  in  the reduction of Cr(VI)
(Article and Fuller 1979).   Bartlett and James (1979),  however, demonstrated
that under conditions prevalent  in many soils, Cr(III)  can be oxidized.   The
presence of oxidized Mn, which  serves  as  an electron  acceptor, was  determined
as an important factor in this  reaction.
     Industrial   use  of  chromium  also  includes  organic  complexed
Organically compl exed Cr(III)  may remain mob-He  in  soil  (James  and
1983).    In  addition  to decreased  Cr(III)  sorption,  added organic
                                                                      Cr(III).
                                                                      Bartlett
                                                                   matter  may
                                      101

-------
     14

     11'

     1.0


     06


     0.6

     04

     0.2

     00

    -02

    -Q4

    -0.6
                               H,0
                                          10 I? 14
'gure  3-29.  Eh-pH diagram of  Cr  species  in  water at 25C calculated (Bart-
            lett  and Kimble  1976a).   Used by permission, see  Copyright
            Notice.
                UJ
                Q.
                      20 i
                      15 -
                C o
                o    10
                co  o>
                 O
                > 2
                o
                 V
                 E
5 -
                       0 -
             sorption
                         02      A      6       8

                                  SORPTION pH
                                  i
                                  10
 gure 3-30.   Sorption of  Cr(VI) on  NaOH-extracted  soil.   (Modified from
             Bloomfield  and Pruden 1980.)
                                    102

-------
                                  \
                             23456
                                      pH
Figure 3-31.   Concentration  of Cr(III) in  24-hour  equilibrium  solutions as a
              function  of  pH (HCl-CaC03) and  presence  of Marlow Ap  soil.
              Initial  concentration  was  5 ymole CrCl3/ml (Bartlett and  Kimble
              1976a).   Used  by permission,  see Copyright Notice.
also facilitate the  oxidation  of Cr(III) to  Cr(VI).   Under different condi-
tions,  this organic matter may facilitate  the reduction of Cr(VI) (James and
Bartlett 1983).

     Mercury--The  distribution  of mercury species in soils, elemental mercury
(Hg),  mercurous ions (Hg22+)  and mercuric  ions  (Hg2+), is dependent on  soil
pH and  redox.   Cationic  mercury forms may be  sorbed  earily  onto  soil constitu-
ents.  Divalent mercury is rapidly and strongly complexed  by covalent bonding
to organic matter  and inorganic  particles.   Walters and Wolery (1974) stated
that as much as 62 percent of the mercury  in  surface soils was  bound to these
particles.  Mercuric  ions are  also bound  to exchange  sites of clays and
hydrous oxides  of  iron  and manganese.   Sorption  is pH dependent, increasing
with increasing pH.

     Mercurous  and mercuric mercury are  also immobilized  by precipitation
with phosphate, carbonate,  and   sulfide.    Precipitates   of  Hg(OH)2>  HgS04,
HgNOs,  and Hg( 1^3)4  are  insoluble  at high  pH.  Insoluble  HgS and HgCl3 occur
at  all  pH ranges.   Divalent mercury will  also form  complexes with soluble
organic matter, chlorides, and hydroxides  which  may contribute to its mobil-
ity.

     The major  loss of mercury from  soils  is  through volatilization.  Griffin
and  Shimp  (1978) estimated that  the removal of Hg from  a  leachate was not due
to sorption by clay,  but are  due  to  volatilization  and/or  precipitation.   This
removal of mercury increased with pH.  Rogers  (1979) also  found large amounts
of mercury volatilized  from soils.   Amounts of mercury  volatilized  appeared  to
be  affected  by the  solubility of  the mercury compound  added  to  soil (Table
3-38).   Volatilization  was also found to  be inversely related to soil  sorption
capacity, thus losses followed  sand  > loam  >  clay  (Table 3-38).

     Under  mildly  reducing  conditions,  both  organically  bound  mercury and
inorganic mercury compounds may  be degraded to the  elemental form  of mercury,
HgG.   Mercury metal  can  readily be  converted to methyl  or ethyl  mercury  by
microbial  transformation.   These are the  most  toxic  forms of mercury.   Both


                                      103

-------
       TABLE 3-38.   PERCENT OF APPLIED Hg  EVOLVED FROM  SOILS WITHIN 144
                              HOURS  (ROGERS  1979).
                    Used  by  permission, see  Copyright Notice
                     	% Hg Evolved	

Hg Compound               Sand             Soil  Loam              Clay
HgO-2
Hg(N03)2
Hg(C2H302)2
HgO
HgS
38.3
36.5
26.4
19.6
0.2
32.9
24.1
30.5
15.0
0.3
14.2
13.4
12.1
6.4
0.2
methyl  and ethyl  mercury are volatile and soluble in water.  The formation of
methyl  mercury occurs primarily under acid conditions, while dimethyl mercury
is produced  at near neutral  pH.

     Arsenic--In  the  soil  environment,  arsenic  exists  as  either  arsenate,
As(V) or as  arsenite,  As(III).   Arsenite  is the more  toxic  form  of  arsenic.

     The behavior  of  arsenate  in  soil  has  been  assumed  to be analogous to
that of  phosphate, because  of  their chemical  similarity.   Like phosphate,
arsenate is  fixed to soils and  is thus relatively immobile.  Iron, Al,  and Ca
influences  this  fixation  by forming  insoluble  precipitates  with  arsenate.
Texture is often  related to As(V) fixation.  The reason  for  this relationship
is that both reactive  Fe and  Al  usually vary  directly with  clay  content  of the
soil.  Woolson et  al . (1971) stated that  arsenate may  be leached from  soil  if
the level of reactive Fe, Al, and Ca  in  soil  are  low.  The solubility  product
for FeAs04  is  reported  as  5.7xlO~21,  whereas for Ca3(As04)2 it  is 6.8x10"^.
The presence of Fe  in soils  is  therefore most effective  in controlling  arsen-
ates1 mobility.  Arsenite compounds  are reported  to be  4-10 times more  soluble
than arsenate compounds.

     Griffin and Shimp  (1978),  in a  sorption  study  of  arsenate by  kaolinite
and montmorillonite, found maximum sorption of As(V) to  occur at  pH  5  (Figure
3-32).    In  comparing  these  sorption  curves  with  the distribution diagram of
As(V) (Figure  3-33), they  concluded  that H2As04" ion was  the principal  As(V)
ion  being  sorbed by the  clays.  The non-sorption of  HAs042-  Was apparently
due  to  repulsion  of  the  ion  from  the  clay surface  resulting in  decreased
sorption of As(V) above  pH 5.


                                      104

-------
                < 200 ->
                    ril /*    \v
100-
0
(
/.v \ \
***>" /"^X \
?o.s /i \ \
'/ft/ \ v
/ /  ; ^
2/.1 lio.a \

\
3246802468 1C
pH
Figure 3-32.   The  amount of  As(V)  removed from DuPage  leachate  solutions by
              kaolinite  and montmorillonite at 25"C plotted  as  a function of
              pH.   Initial  solution concentrations  of  As(V)  are given in ppm.
              Each  data  point was obtained by using either 4 g of kaolinite or
              1  g  of  montmorillonite  in  a  total  solution volume  of 52.5 ml
              (Griffin and  Shimp 1978).
                                      A AsOZ)
                                                 pH
Figure 3-33.   Diagram  showing  distribution of  forms of  As(V)  (Griffin  and
              Shimp  1978).
                                     105

-------
     The sorption  of  As(III)  is  also  strongly  pH-dependent.    Figure  3-34
shows  increased sorption  with pH  in  the pH range  3-9 (Griffin  and Shimp
1978).    These  authors  concluded  that  this  increased  sorption  with  pH  was
due to  an increase  in concentration of monovalent  As(III) species  with  pH.

     Under  anaerobic conditions-,  arsenate may  be reduced  to  arsenite.    The
reduced form of arsenic is more subject to  leaching  because  of  its  increased
solubility.   Arsenite  may also  be  volatilized  from soils.   High organic
matter,  warm temperatures,  adequate  moisture,  and other conditions con-
ducive  to microbial  activity drive  the reaction  sequence  toward methylation
and volatilization  which  reduces arsenic  residues  in  soil  (Woolson  1977).
Wool son's (1977)  study showed that only 1-2 percent of the arsenate  applied  at
a rate  of 10 ppm was volatilized as arsine (AsH3)  in 160 days.

     SeleniumForms  and  concentrations  of  selenium  in  soil  solution  are
governed by various physical  and  chemical  factors expressed  in terms of  pH,
dissolution   constants,  solubility  products,  and  redox potential.    Figure
3-35 illustrates a phase  diagram  for selenium.   Selenate, Se(VI)  is  the
predominant  form of  selenium  in  calcareous  soils and  selenite,  Se(IV),  is
the predominant  form  in  acid  soils.

     Selenite can be bound  to sesquioxides,  especially to Fe  oxides.   Griffin
and Shimp (1978)  found  maximum sorption of  selenite on montmori11inite  and
kaolinite to  occur  at pH 2-3  (Figure 3-36).

     Selenium is least  soluble  under  acid  conditions.   Precipitates  of selen-
ite by  ferric hydroxide  in  acid soils is presumed  to be the factor in reducing
selenium's  mobility.   In the solubility diagram  (Figure  3-37, Geering et  al.
1968),  selenous  acid  potential  (pH  +  pHSeO^)  is plotted  against the ferric
hydroxide potential  (pH-l/3pFe).    The solid  line  represents  an  estimated,
average  formation  potential  for  the  compounds  Fe2(Se03)3 and  Fe2(OH)4Se03.
For the  soils used  in  this study, all  fall  along the Fe(OH)3 line  and  below
the ferric  selenite  lines,  indicating  that  crystalline  ferric selenites  are
not governing  the  observed  selenium  solubility  in  these soils.   Selenite
probably forms  sorption complexes with  ferric  oxides  in  soils  rather  than
crystalline  ferric  selenite.

     In contrast to  selenite,  selenate,  Se(VI),   is  highly mobile   in  soils.
Selenate dominates  under alkaline  conditions.  Unlike most metals, selenium is
more mobile  at higher  pHs.

     Under  reduced conditions,  selenium  is  converted to  elemental   form
(Figure  3-35).   This conversion can  provide  an  effective mechanism  for
attenuation  since  mobile  selenate occurs only  under well aerated,  alkaline
conditions.

     Si 1ver--SiIver is very strongly sorbed by clay  and organic matter.
Precipitate  of silver, AqCl,  Ag2S04,   and Ag2C03, are highly insoluble.   Silver
is  highly immobile  in   the soil  environment.   Published data concerning  the
interaction  of Ag with  soil are rare.

     Beryl 1ium--Although beryllium is considered  the most  toxic metal  in  the
environment,   few  studies   have  been done on  the  chemistry  of beryllium  in


                                     106

-------
                                            Montmor li lonite
                     ;oo-
Figure 3-34.   The amount of As(III) removed from  DuPage  leachate  solutions  by
              kaolinite  and montmorillom'te at  25C  plotted as a function  of
              pH.   Numbers give the initial solution concentration  of  As(III)
              in  ppm.   Each data point was obtained  by using  4 g  of clay  in a
              total  solution  volume  of 52.5 ml  (Griffin and  Shimp  1978).
soil.   Berillium  is  known to  be  strongly  adsorbed  at  exchange  sites  and
is readily  precipitated by  liming.   Beryllium  is  an  alkaline  earth  metal
(the  same  group as  Ca  and Mg)  and  presumably its  activity  in  soils  would
be controlled  by  the same  solution chemistry  as  other  metals.  Generaliza-
tions are,  however, impossible.

SOIL  SORPTION - ORGANICS

     Soil  sorption is perhaps the most  important  soil-waste  process  affecting
the  toxic  and  recalcitrant fractions  of  hazardous waste.   The  influence  of
soil  sorption  on   the  extent  and  rate of  leaching,  and  also on  biological
decomposition of these fractions must be understood and described in order to
effectively use the  sorption reaction  as  a treatment process.   Understanding
the  effect of  different solid   surfaces on  hazardous  waste  constituents  pro-
vides  a  mechanism for  rationally   selecting  additional  sorbents for use  in
augmenting  the  natural  ability of  a soil   system  for  immobilizing  hazardous
chemicals.    Also,  understanding the  relationship  between  soil water  content
and  extent of  sorption of  hazardous chemicals  provides  the  hazardous  waste
manager with  a process for controlling the potential release and  migration of
constituents  through  leaching.   Thus, this  section of the manual  describes the
factors  involved   in  soil  sorption  of chemical  constituents  and   the  basic
parameters  influencing  the sorption  process that may be  used  in  treatment
processes for immobilizing  specific  hazardous waste fractions.

     Soil  sorption is a physical/chemical process  which  involves  the increase
of solute at  tne soil  water interface.  The  terms sorption  and adsorption will

-------
     + 1.2




     + 1.0




     + 0.8




     + 0.6




     + 0.4




 >   +0.2

 -C
 LU

        0




     -0.2




     -0.4




     -0.6
  ASSUMED  BOUNDARY
     OF NORMAL
SURFACE CONDITIONS
                                      I	I
        I	I
                                      6       e
                                        PH
       10
12     14
Figure  3-35.  Stable fields of selenium (Brown and Associates,  Inc. 1980)
                                  108

-------
                    026802468IO
Figure 3-36.  The  amount  of Se(IV) removed from DuPage leachate  solutions  by
             kaolinite and montmorillonite at  25"C, plotted  as  a function  of
             pH.  Numbers are the initial solution concentration of Se(IV)  in
             ppm.   Each  data point was obtained by using either  5 g  of
             kaolinite or  1  g of montmorillonite  in a total  solution  volume
             of 52.5 ml (Griffin and Shimp 1978).
                                   109

-------
                     12 
                     13 L-
                      00
 1...
O 5
L. _
I O
                                   pH-
                                                  20
Figure 3-37.  Solubility  diagram for the  ferric  selenites, and  the solubility
              data obtained  from 1:10 soil-O.OlM Ca  (N03)2  extracts of several
              soils  (Geering et al.  1968).   Used  by permission,  see Copyright
              Notice.
                                                  Reproduced from
                                                  best  available copy,
                                      110

-------
be  used  interchangeably  to  include  both  adsorption  and  absorption,  unless
otherwise stated.  Sorption represents an important soil  mechanism for removal
of pollutants from the soil solution.   The pollutants are "immobilized" by the
soil, hence  preventing  polluted  groundwater.   In this section  adsorption and
factors  affecting  adsorption  that  may be used for  controlling,  managing, and
treating  hazardous  constituents  are  discussed.    Thorough  descriptions  of
adsorption can be  found  in comprehensive  reviews  by Davies  and  Rideal  (1963),
Kipling  (1965),  Ekwall  et  al.  (1963), Bailey  and  White (1970),  and  Hamaker
and Thompson (1972).

     Sorption  can  be "specific" or  "nonspecific."   Specific sorption occurs
when  specific  sites on  the surface exert  forces on  a  particular unit  of  a
molecule at a certain configuration, for example,  adsorption of  fluoride anion
on geothite  (Bohn  et  al .  1979).   Nonspecific  sorption  is more general, and it
precedes  the  specific sorption  due  to lower heat  of  adsorption.  The major
forces  that  make  sorption possible are:  1)  Van der  Waals-London forces, 2)
hydrophobic bonding, 3)  hydrogen bonding,  4)  charge  transfer, 5)  ligand
exchange, and 6) chemisorption.

     Van  der Waals-London  forces  are weak  electrostatic  forces which  are
caused  by uneven distribution of electrons of  molecules due to the circulation
in their orbits.   This motion causes  an  instantaneous  dipole which results in
attraction.  Van der  Waals  forces  are  weak  forces;  however, they are  additive
forces.  Van der Waals forces become significant for large molecules when they
interact  with  the  soil  surface at  a  few  sites.   Van  der Waals  bonding is
important for organic molecules.

     Hydrophobic bonding  is actually  a  partitioning  between a  polar  solvent
(e.g. water) and a nonpolar  adsorbent  surface (e.g.  soil  humus).   Hydrophobic
bonding  is  a phenomenon related to  entropy at  low temperatures  (Hamaker and
Thompson 1972).  The  entropy  is  decreased as  a  result  of hydrophobic  compound
dissolution  in water.   Hence, the  molecules  tend to leave  water  to  increase
the entropy  and  accumulate on hydrophobic  regions  of  the  adsorbent  (organic
matter  of  the soil).   At  higher  temperatures,  the enthalpy of  transfer  of
molecules from  adsorbent  surface  to  the  water  increases  which leads  to  the
unfavorable condition where the  molecule reenters  the soil  water.   Hydrophobic
bonding  was  used  to  explain  the high  correlation  observed between the  soil
adsorption  coefficients   normalized  for  percent organic   carbon  (Koc),  and
octanol/water  partition   coefficient   (Kow)   for  nonionic   and  polar  organic
compounds (Karickhoff et  al.  1979, Karickhoff  1981,  and Chiou  et  al.  1983).
This correlation will be discussed  in  detail.

     Hydrogen bonding  is   a  special  case of  charge transfer.   The  hydrogen
bond is a weak electrostatic bond and  occurs between hydrogen and  two  atoms of
high electronegativity (e.g., F, 0, and N).   Energy of adsorption  in  hydrogen
bonding ranges from 0.5  -  15 kcal/mole.  Hydrogen  bonding becomes  more  signif-
icant with larger molecules, as  in the case of  Van  der Waals bonding.   Hydro-
gen bonding  has  been  suggested  for  the  adsorption of  s-triazine herbicide
molecules (Hamaker and Thompson  1972).

     Charge  transfer  is   a  partial overlap of  molecular orbitals  of  two
molecules in  an  electron  donor-acceptor  system.    Charge  transfer complexes


                                      111

-------
are formed between bonds or lone pairs of electrons.  Charge transfer adsorp-
tion is an important mechanism  in adsorption of organics (Hamaker and Thompson
1972).

     Ligand  exchange  is a replacement of  one  or  more ligands by an adsorbent
molecule.   This replacement occurs only  if an  adsorbent molecule is a stronger
chelating  agent  than  the  ligand.   For example,  bipyridines  and  organophos-
phates  can be adsorbed  by  ligand  exchange  (Hamaker and Thompson 1972).

     Ion exchange  is  a process  in  which  a cation  is taken  from  a solution
to  replace  another cation  adsorbed  on  the  soil  surface.    Cation  exchange
involves  Coloumbic forces which reach up to 50 kcal/mole.  Many organic
molecules  will  be exchanged   upon  protonation   in  soil  including  alcohols,
amines,  and carbonyl  groups.  After  protonation these  molecules can be
adsorbed on  clay surfaces  (Hamaker and Thompson 1972).

     Chemisorption is  an  exothermic process  with  an energy  range  of  30-190
kcal/mole  (Merrill et  al.  1982).   Usually,  chemisorption  involves  a chemical
bonding between adsorbent  and  adsorbate.  In  short-term sorption studies  (<12
hours)  the occurrence  of  chemisorption  is low.   However,  chemisorption might
be very important in  the  long-term  immobilization of organic constituents and
in influencing their fate  in soil  systems  (Osgerby 1970).

     The sorption behavior of  organic compounds  can be simplified  by catego-
rizing  organics into functional  classes  (Weber 1972).   The two major classes
are:  1) ionic and 2)  nonionic  compounds.

Ionic Compounds

     Organic ionic compounds  consist of basic, cationic and acidic compounds.
Organic basic  compounds  represent  organic  constituents that  are  capable of
accepting a  proton to  become   an  ionized  cation.   Properties of basic pesti-
cides,  taken  from Weber  (1972), are  shown  in Table  3-39.   Three mechanisms
that function in adsorption of  basic compounds by soil organic  matter include:
1) ion exchange, depending on  protonation, 2)  hydrogen bonding, and 3) hydro-
phobic  bonding, which  is  greatest  at  higher pH  values when the molecules are
not  protonated.   Acidic  groups  of soil  organic  matter have  an  average pKa
value  of  approximately 5.5 (Hayes  1970).   Some  acidic  functional  groups of
fractions of soil organic  matter  have pKa  values less  than three (fulvic
acid) and 3.4 to 3.6  (humic acids)  (Gamble 1970 and  Gilmour  and Coleman 1971).
Adsorption of s-triazine molecules  to  soil organic matter  is attributed to the
complexing  of  the s-triazine  molecule by  ionizable  H+  ions on  functional
groups   of organic colloids  and to  adsorption  of  protonated  species  by ion
exchange  (Weber et al.  1969).   Factors shown  to  influence the  adsorption
of the s-triazine class of organic  bases  in soil  systems  include:   1) molecu-
lar  structure, basicity,  and solubility; 2)  type of  clay mineral;  3) acidity;
4)  type  and concentration of  ions  in  solution  and on clay  surface;  and 5)
temperature.

     Talibudeen  (1955) reported  that  organic   nitrogen  bases  react  direc-
tly  with  H-montmorillonite through a cation-exchange  mechanism  which is
pH  dependent.    Strong bases  were  adsorbed  more   strongly  than  weak bases.


                                      112

-------
TABLE 3-39.  PROPERTIES OF BASIC  PESTICIDES (WEBER 1972)
       Used  by  permission,  see  Copyright  Notice
Common
Name or
Designation
Atrazine

Propazine

Simazine

SD-15418


Ametryne

Prometryne

Desmetryne

Terbutryne

Atratone

Prometone

Hydroxy
Propazine
Menazon


Amitrole
Trade
Name
AAtrex

Milogard

Princep

Bladex


Evik

Caparol

Semeron

Igran

Gesatamin

Pramitol

"Degradation
product"
Saphos


Amino Triazole
Chemical
Name
2-chloro-4-ethylamino-6-iso-
propyl-amino-s-triazine
2-chloro-4,6-bi si sopropyl -ami no-
s-triazine
2-chloro-4,6-bi si sopropyl ami no-
s-triazine
2-chloro-4-(l-cyano-l-methyl-
ethyl amino)-6-ethyl amino-s-
triazine
2-methyl thio-4-ethyl amino-6-
isopropylamino-s-triazine
2-methyl th i o-4 , 6-b i s i sopropyl -
amino-s-triazine
2-methyl thi o-4n-methyl ami no-6-
i sopropyl amino-s-triazine
2-methyl thi o-4-ethyl ami no-6-
tert-butyl amino-s-triazine
2-methoxy-4-ethyl ami no-6-
i sopropyl amino-s-triazine
2-methoxy-4,6-bi si sopropyl amino-
s-triazine
2-hydroxy-4,6-bisisopropl amino-
s-triazine
S-(4,6-diamino-s-triazin-2-
ylmethyl )-0,0-dimethylphos-
phorodithioate
3-amino-s-triazole
pKa
1.68

1.85

1.65

1.1


3.93

4.05

4.0

4.07

4.20

4.28

5.20

3.8


4.17
Water
Solubility
20-25"C,ppm
pH3 pH/
31 35

4.8 4.8

5.8 5.0

160


404 194

206 40

501

58

1900 1600

1000 677

326 41

250


280,000
Vapor
Pressure
mm Hg 20C
(xlO-6)
0.3

0.029

0.0061

0.01 (830


0.84

1.0

1.0

0.96

2.9

2.3








-------
He suggested that the basic property of  organic  bases was the most important
property  influencing  their adsorption.    Frissel  (1961)  also reported  the
pH-dependency of  organic  bases  (s-triazine  herbicides)  on   adsorption  and
concluded that  triazines  are   adsorbed  as neutral molecules  in neutral  and
basic environments and as positively charged  ions in  acidic solutions.   Weber
(1966) demonstrated  that maximum  adsorption of 13 s-traizines on Na-montmoril-
lonite clay  occurred  in  the vicinity of the  pKa of  each  s-triazine  (Figure
3-38).   The  more  basic  compounds were adsorbed  in greater  amounts than less
basic compounds.  H- and  Al-montmorillonite may be acidic enough to hydrolyze
atrazine to  hydroxyatrazine (Weber  1970).  Generally,  adsorption  of  s-tria-
zines increases  as acidity, organic matter, and clay content of soils increase
(Lavy 1968).

     The mechanism  of  adsorption of basic compounds  to soil   systems  can  be
illustrated   using  the  s-triazine class  of organic bases  as   a model.   The
following processes, taken  from Weber (1970), will be considered:

     R + H+   RH+                                                       (3-15)

     R + X-mont  =  RX-mont                                               (3-16)

     RH+ + X-mont  =  RH-mont + X+                                        (3-17)

     H+ + RH-mont  =  H=mont  + RH+                                        (3-18)

     H+ + X-mont = H-mont + X+                                          (3-19)

     R + H-mont  =  RH-mont                                               (3-20)

where R  = triazine  compound; RH+ =  triazine cation;  X-mont =  montmorillonite
with  X  = exchangeable cations  Na,  Li,   l/2Ca,  l/2Mg,  etc.; H-mont =  hydro-
gen  (aluminum)  montmoril lonite;  and  H+   =  hydrogen  ion, as the  hydrated  H20
species.

   Equation   3-15  is related to  the basicity  of the  compound,  indicated  by
the equilibrium  constant  Ka, given by:

     pKa = log [(RH+)/(R)]  + PH                                         (3-21)

As indicated previously,  maximum  adsorption  occurs  at  a pH equal  to  the
pKa of the compound.

     Equations  3-16  and  3-17  represent   adsorption of netural  and  cationic
s-triazines   by  montmorillonite.    Equations  3-17,  3-18,  and  3-19  indicate
competition of s-tria-zine molecules with  other cations for soil  sites.
Equation  3-20  indicates   s-triazine  adsorption  through direct  complexation
with hydrogen ions on  H-montmorillonite.

     The effects of pH on  organic base  adsorption  is  illustrated as follows,
and  is  taken from  Weber (1970).   As  the pH  is decreased,  the  s-triazine
molecules become protonated (Equation 3-15), and  these cations are adsorbed by
clay minerals such as montmorillonite in  exchange for  X (Equation 3-17).  The

                                     114

-------
  n>
  CO
   I
  CO
  CO
           AMOUNT OF ORGANIC COMPOUND ADSORBED-(|imol*/l)
o    o    o    o     o
o    o    o    o     o
                                                 O
                                                 o
_-;   -t> o
^  . fO
-  r>
 o *"
t/> Cu
CT" ^
3 3 U
T3 0
fft CT Ql
1 *"*" ^~ t
5 TO ^ ^ *
5 -< o
E -a 
' 3 !l P "
g O-o 5
 3 "

in 0- 0 5 *
ns o ~*> 5
!--+> * -1
0 o 
S  "*
TJ ._ j  '
_. 2 fO
ua ai __i
Saft
O fD
Z 3 CL
0 - -
f-f- ;j (/> 
^' o '
n ;i rt-
fD ^ 1
 .j>
 ' N
O -.
3 3
-4. m
rt "
	 1 	 1 	 1 	 1 	 1 	 1 r

-> "\ *^^
N.x. o. N
\*% ^ v
- '? X <
- t\ fS V1
'X * I \ I \
** \S O\ 4
'  I*N^  ol "3
9 ** t^ i ri /^ *
2 < O
I "I / /'
1 * xCf ^*
 1 rf' > '
 /o 

p  X
/ s '
/09% /
/' /
'/ -S>~1
?//* Ss' '
/./
F 

n
O








                                                            -
                                                                    HERBICIDE  ADSORBED  (M molt /g)
CT


-S -

-------
result is an increase in  adsorption.   Addition of  acid  also causes some of the
X  cations  on the  clay to  be replaced  by  hydrogen (Equation  3-19)  and the
resulting H-montmorillonite may  absorb neutral  R molecules  (Equation 3-20).
When the  pH equals approximately the  pKa,  adsorption  reaches  a maximum.  As
pH is increased further,  adsorption is decreased.    The decrease  in adsorption
is attributed  to  competition  from the  H+  ions  (Equation 3-18).   It  is also
known  (Weber  1970)  that  salts  such  as barium  chloride (O.lm)  cause  "large
decreases in  adsorption  of these basic molecules  because  Equation  3-17  is
driven to the left, releasing  the s-triazine cations to the solution.

     Adsorption of  s-triazine  bases  has also been  reported  to be relatively
independent  of soil pH.  The s-triazine molecules atrazine, propazine, prome-
tone, and prometryne were  found  to adsorb  to 30 soils varying  in pH from 4.9
to 7.6 according to the linear Freundlich isotherm:

     Y = Kd  C                                                          (3-22)

For soils containing greater than 5 percent  carbon,  adsorption  was independent
of clay content  and directly dependent on  soil  organic  matter.   Aqueous
solubility  did  not influence  sorption.  Thus,  adsorption of basic compounds
may  also be due  to a partitioning out of aqueous solution  onto nonpolar
hydrophobic  surfaces,  in  addition to  specific  charge  related   sorption  sites
(Walker and  Crawford 1968).

     Desorption of  s-triazine  molecules from soil  minerals  and soil   organic
matter occurs  relatively  easily  in the  presence  of distilled  water.   Strong
bonding of these organic  bases to soil  components  is not  indicated.

     Cationic compounds generally are characterized by high-water solubility
and  by  strong  adsorption  to  clay fractions of soils.   Examples of strongly
adsorbed cations include the compounds paraquat and diquat.  The mechanism of
adsorption  involves  cation exchange.    That is,  a  positively  charged cation
associated  with a  clay mineral is  displaced by the  positively  charged  organic
cation.   Cation  properties are   shown  in  Table  3-40  for  several  compounds.

     Acidic  compounds (anionic  compounds)  contain functional  groups  which
may  ionize  to  produce organic anions.   The tendency  to ionize is described
by the dissociation constant,  Ka:

     RCOOH  = RCOO- + H+                                                 (3-23)

     pKa =  PH - log [(RCOO-)/(RCOOH)]                                    (3-24)

where  RCOOH is the undissociated molecule  and  RCOO- is the   anion species.
Properties  of acidic  compounds  are shown   in Table 3-41.    Weak acids, with
relatively  higher  dissociation constants than strong  acids,  are in the free
acid  form  at  pH  values below their  pKa values  and  are adsorbed  to a much
greater  extent  than  in  dissociated (anion) form.   Due to  the net  negative
charge  associated  with clay minerals,  there is  a  net repulsion between  the
negatively  charged organic anion and  soil  fractions  including minerals  and
organic matter.   However,  Harter  and  Ahlrichs (1967)  demonstrated  that the pH
of water  at the clay surface   is  lower  than in an  aqueous soil  bulk solution.


                                      116

-------
TABLE 3-40.  PROPERTIES OF CATIONIC PESTICIDES (WEBER 1972)
        Used  by  permission,  see  Copyright  Notice
Common
Name or
Designation
Diquat
Paraquat
Chlormequat
Morfamquat
Methyl ene blue
Phosphon
Hyamine
Phenacridane
chloride
Et. Pyr. Br.
Pyr. Pyr. Cl.
Trade
Name
Ortho diquat
Ortho paraquat
Cycocel
Ceroxone

Phosfon
Hyamine 10-X
Acrizane


Chemical
Name
6,7-dihydrodipyrido[l,2-a:2',l'-
c]pyrazidiinium dibromide
1,1 '-dimethyl -4, 4 '-bypyridinium
dichloride
(2-chl oroethyl ) -tr imethyl -
ammonium chloride
l,l-bis(3,5-dimethylmorpholino-
carbonylmethyl )-4,4' -bipyridyl ium
dichloride
3, 7-bis (dimethyl ami no )-phenazathionium
chloride
tributyl-2,4-dichlorobenzyl phos-
phonium chloride
di-isobutyl cresoxyethoxy-ethyl dimethyl -
benzyl ammonium chloride, mono-
hydrate
9-(p-n-hexyloxyphenyl)-10-methyl-
acridinium chloride
1-ethylpyridinium bromide
N-(4-pyridyl )-pyridinium chloride
Molecular
Weight
344
257


374
398
480
406
188
193
Water
Solubility
20eC,%
70
70
74

4
high
high
high
high
high

-------
                           TABLE 3-41.  PROPERTIES  OF ACIDIC PESTICIDES (WEBER  1972)
                                  Used  by  permission,  see  Copyright  Notice
CO
Common
Name or
Designation
2,4-D
2,4,5-T
MCPA
MCPB

Silvex

Chlorainben
Dicamba
Tricamba
2,3,6-TBA
TIBA
Fenac
Benzadox
Picloram

Endothall

N apt a lam
Dalapon
TCA
UMSA
MH
Dinoseb
DNOC
loxynil
Bromoxynil
Trade
Name
Weedone 638
Brush Killer
Methoxone
Thistrol

Kuron

Ami ben
Banvel D
Banvel T
Benzac
Floraltone
Fenac
Topicide
Tordon

Endothall

Alanap
Dowpon
TCA
Alar
MH-30
Premerge
Sinox
Certrol
Brominil
Chemical
Name
2,4-dichlorophenoxyacetic acid
2,4,5-trichlorophenoxyacetic acid
(4-chloro-o-tolyloxy)acetic acid
4-(4-chloro-o-tolyloxy)butyric
acid
2-(2,4,5-trichlorophenoxy)pro- *
pionic acid
3-amino-2,5-dichlorobenzoic acid
3,6-dichloro-o-anisic acid
3,5,6-trichloro-o-anisic acid 
2,3,6-trichlorobenzoic acid 
2,3,5-triiodobenzoic acid *
2,3,6-trichlorophenylacetic acid
Benzamidooxyacetic acid ^
4-amino-3,5,6-trichloropicolinic
acid
7-oxabicyclo[2.2.1]heptane-2,3- %
dicarboxylic acid
N-1-naphthylphthalmic acid *
2,2-dichloropropionic acid
trichloroacetic acid
N-dimethylamino succinamic acid ^
l,2-dihydro-3,6-pyridazinedione **
2-sec-butyl-4,6-dinitrophenol
4,6-dinitro-o-cresol
4-hydroxy-3,5-diiodobenzonitrile
3,5-dibromo-4-hydroxybenzonitrile
pKa
2.80
2.84
3.11
4.80

3.0

3.40
1.93
1.5
1.5
1.5
3.70
4.7
1.90

4.0

4.0
1.84
0;63
4:0
4.0
4.40
4.35
3.96
4.08
Water
Solubility
20-25eC,ppm
650
238
550
44

140

700
4500
si. sol.
8400
si. sol.
si. sol .
19,000
430

10,000

200
450,000
1,300,000
si. sol.
6000
52
130
1.8
130
Vapor
Pressure
mm Hg 35C
(xlO-6)





low

very low


negligible



0.62

negligible

low
0
0

" 0
>1.0
1.0-52.0
negligible
negligible

-------
With suspension pH values  of  6,  5, 4  and  3,  it was estimated that  the  pH at
the clay surface was  approximately 4.5, 4.0,  3.2 and 2.5 respectively.   Water,
therefore, is more  acidic  at clay surfaces than  in the bulk solution.   This
phenomenon may play  a  role in the adsorption of acidic  compounds  so that the
extent of adsorption  to clay surface  is higher than is  expected  from  the pH of
the bulk solution.

     However,  anion  adsorption  can  occur  in  soil  systems to  other  soil
components.  The  reaction  of an  organic  anion with iron and aluminum  oxides
can be illustrated as follows:

     Anion- + A1(OH)3+ = A-A1(OH)3                                      (3-25)

Arsenates and phosphates can also  react as follows:

     CH3-As-OHOO- + Fe(OH)2+ = CH3-As-OHOQ-  Fe(OH)2                 (3-26)

Therefore, adsorption  of  organic  anions  does occur,  and   usually  does  not
involve ion exchange, as with  organic  cations  such  as paraquat and  diquat.

     Acidic organic molecules,  including  pesticides,  ionize  in  soil  solution
to form  anionic  species.   The pH at which ionization  occurs  depends upon the
pKa value for each organic acid.   Under normal pH values for soil  solutions,
the anionic forms predominate.  Since  soil  inorganic and organic  fractions are
generally negatively charged at normal pH  values for soil,  organic  acids tend
to be relatively mobile.  Thus,  highly water  soluble,  acidic organic  molecules
comprise one  of  the most mobile  classes of organic  chemicals in  soil  systems.


Nonionic Compounds


     According  to Weber  (1972), nonionic  pesticides consist of  the  following
families of  compounds:   1) chlorinated  hydrocarbon;   2) organophosphates;  3)
substituted  anilines;  4)  phenyl  carbamates;  5) phenylureas;  6)  substituted
anilides; 7)  phenylamides;  8)  thio carbamates, carbotioates, and  acetamides;
9) Benzonitrites; and  10)  esters.   Nonionic  compounds do not ionize signifi-
cantly in  aqueous or soil  systems.   These families  of compounds are  highly
variable in  their properties, not only among  the ten families of  compounds
mentioned, but  also   among the  individual  compounds  within each  family  of
compounds (Table 3-42).

     The nonionic nonpolar compounds  in  general  adsorb at  the  hydrophobic
regions of the  soil.   In  other words,  organic carbon  content  of soil  is  a
very important factor  in adsorption of nonionic nonpolar compounds  (Lichten-
stein  et  al. 1960;  Gr.aham-Bryce  1967;  Kay  and   Elrick  1967;  Lambert  1967;
Whitney 1967; Harris  et al.  1969;  Shin et  al. 1970;  Peterson  et  al.  1971;
Felsot and  Dahm  1979;  Karickhoff et  al.  1979; Wahid and  Sethunathan  1978,
1979,  1980; Kozak  and  Weber 1983; Nkedi-Kizza  et  al.  1983).   For polar  com-
pounds, adsorption occurs  in competition  with water  molecules  on  adsorbent
surface (Guenzi  and Bread  1967).   The adsorption  is negatively  correlated  to
the solubility of compounds, while desorption  was proportional to the solubil-
ity (Sharom et al. 1980).


                                      119

-------
                  TABLE 3-42.  SELECTED PROPERTIES OF SOME NONIONIC  PESTICIDES (WEBER 1972)

                                  Used by  permission,  see  Copyright  Notice
ro
o
Common
Name or
Designation
Trade
Name
Chemical Water
Name Solubility
20-25C,ppm
Vapor
Pressure Parachor
mm Hg 20-25
C (xlO-6)
Organophosphates
Dimetnoate


Methyl
parathion
Phorate

Demeton

Parathion

Disulfoton

Dursban

Diazinon


Malathion

Carbophe-
nothion
Ethion

Schraden
Cygon


Metron

Thimet

Systox

Phoskil

Disyston

Dursban

Diazol


Cythion

Trithion

Nialate

OMPA
0, 0-d imethyl -S-(N-methyl carba-
moyl -methyl) -phosphorodithio-
ate
0,0-dimethyl -0-p-nitrophenyl
phosphorothioate
0,0-diethyl-S-(ethylthio)-methyl
phosphorodithioate
0,0-diethyl-0(and S)-[2-ethyl-
thio)-ethyl ]phosphorothioates
0,0-diethyl -0-p-nitrophenyl
phosphorothioate
0,0-diethyl -S-[2-(ethylthio)-
ethyl] phosphorodithioate
0,0-diethyl-0-(3,5,6-trichloro-
2-pyridyl) phosphorothioate
0,0-diethyl -0-(2-i sopropyl -6-
methyl-4-pyrimidinyl ) phos-
phorothioate
0,0-dimethyl-S-(l,2-dicarbethoxy-
ethyl) phosphorodithioate
0, 0-di ethyl -S-(p-chl orophenylthi o-
methyl ) phosphorodithioate
0,0,0 ' ,0 ' -tetraethyl -S ,S ' -methyl -
ene biophosphorodithioate
Octamethyl pyrophosphorami de
20,000


50

80-85

100

24

60-66

2

40


145

1-2

1

misible
100




2300

1000

37.8

300

18.7

140


40





1000
484


529

573

553-583

609

613

659

693


699

707

815

689

-------
  TABLE 3-42.   (CONTINUED)
Common
Name or
Designation
Trade
Name
Chemical Water
Name Solubility
20-25C,ppm
vapor
Pressure
mm Hg 20-25
C (xlO-6)
Parachor
Chlorinated hydrocarbons
DDT
Methoxychlor
Endrin
Dieldrin
Aldrin
Toxaphene
Lindane
Chlordane
Heptachlor
Substituted anil
Nitralin
Benefin
Triflural in
Gesapon
Mar late
Endrin
Octalox
Drinox
Phenacide
Gamexane
Octa-Klor
Drinox
H-34
ines
Planavin
Balan
Treflan
l,l,l-trichlor-2,2-bis(p-chloro- 0.001-0.04
phenyl)-ethane
2, 2-bis(p-methoxyphenyl )-!,!, 1- 0.1-0.25
trichloroethane
l,2,3,4,10,10-hexachloro-6,7- 0.23
epoxy-l,4-4a,5,6,7,8,8a-octa-
hydro-l,4-endo-endo-5,8-di-
methanonaphthalene
l,2,3,4,10,10-hexachloro-6,7-epoxy- 0.1-0.25
l,4-4a,5,6,7,8,8a-octahydro-l,4-
endo-exo-5,8-dimethanonaphtha-
lene
l,2,3,4,10,10-hexachloro-l,4,4a,5, 0.01-0.2
8,8a-hexahydro-l,4,-endo-exo-5,8-
dimethanonaphthalene
mixture made by chlorinating cam- 0.4
phene to 69% chlorine
l,2,3,5,6,7,8,8-octachloro-2,3,3a, very low
4,7-7a-hexahydro-4,7-methanoin-
dene
l,4,5,6,7,8,8a-heptachloro-3a,4,7a- very low
tetrahydro-4,7-methanoindene
4-(methylsulfonyl)-2,6-dinitro-N, 0.6
N-dipropyl aniline
N-butyl-N-ethyl- , , -trifluro- 0.5
2,6-dinitro-p-toluidine
, , -trifluro-2,6-dinitro-N,N- 0.05
0.15
0.20
0.18
6.0
1.0
9.4-45.0
10.0
300
1.0
38.9
114
658
699
494
494
493
mixture
478
647
596
768
671
671
di propyl-p-toluidine

-------
                                            TABLE  3-42.   (CONTINUED)
ro
ro
Common
Name or
Designation
Phenylcarbamates
Propham
Dichlormate

Chlorpropham
Carbaryl
Barban

Terbutol

Acetamide
CDAA
Benzonitrile
Dichlobenil
Esters
Methyl ester
of chlor-
amben
Isopropyl
ester of
2,4-D
DC PA

Phenyl ureas
Fenuron
Monuron

Monolinuron

Trade
Name
(and carbanilates)
Chem-hoe
Rowmate

Chloro I PC
Sevin
Carbyne

Azak


Randox

Casoron

Ami ben methyl -
ester

2,4-D ester


Dacthal


Dybar
Telvan

Aresin

Chemical
Name

isopropyl carbanilate
3,4-dichlorobenzyl methylcarba-
mate
isopropyl m-chl orocarbani late
1-naphthyl -N -methyl carbamate
4-chl oro-2-butynyl -m-chl oro-
carbani late
2,6-di-tert-butyl-p-tolyl
methyl carbamate

2-chloro-N,N-diallylacetamide

2,6-dichlorobenzonitrile

methyl ester of 3-amino-2,5-
dichlorobenzoic acid

isopropyl ester of 2,4-di-
chloro-phenoxyacetic acid

tetrachloroterephthalic acid,
dimethyl ester

1,1 -dimethyl -3-phenyl urea
3-(p-chlorophenyl )-l,l-dimethyl -
urea
3-(p-chlorophenyl )-l-methoxy-l-
methylurea
Water
Solubility
20-25C,ppm

250-254
170

88-102
40-99
11-12

6-7


20,000

18-25

120





0.5


2900-3850
230

580

vapor
Pressure Parachor
mm Hg 20-25
C (xlO-6)

426
466

10 466
453
522

706


9.4-9.6 408

0.5 334

426


10-15 533


<10 580


399
0.5 439

150 459


-------
                                            TABLE 3-42.  (CONTINUED)
ro
co
Common
Name or
Designation
Fluometuron

Metobromuron

Diuron

Linuron

C-6313

Norea

Siduron

Neburon

Fluorodifen

Chloroxuron

Substituted ani
Propachlor
Propanil
Alachlor

Dicryl
Solan

Trade
Name
Cotoran

Patoran

Karmex

Lorox

Maloran

Herban

Tupersan

Kloben

Preforan

Tenoran

lides
Ramrod
Rogue
Lasso

Dicryl
Solan

Chemical Water
Name Solubil
20-25'C,
l,l-dimethyl-3-( , , -trifluro-
m-tolyl)-urea
3- ( p-bromophenyl ) - 1 -methoxy- 1 -
methyl urea
3-(3,4-dichlorophenyl)-l,l-di-
methylurea
3-(3,4-dichlorophenyl)-l-methoxy-l-
methylurea
3-(4-bromo-3-chlorophenyl )-l-
methoxy-1-methyl urea
3-(hexahydro-4,7-methanoindan-5-yl)-
1,1-dimethylurea
l-(2-methylcyclohexyl)-3-phenyl-
urea
l-butyl-3-(3,4-dichlorophenyl)-l-
methylurea
p-nitrophenyl- , , -trifluro-2-
nitro-p-tolyl ether
ity
ppm
90

330

42

75

50

150

18

4.8

<2.0

3-[p-(p'-chlorophenoxy)phenyl]- 2.7-3.7
1,1-dimethylurea

2-chlor-N-i sopropyl acetani 1 ide
3', 4' (-dichloropropionanilide
2-chlor-2',6'-diethyl-N-(methoxy-
methyl) acetani 1 ide
3 ' , 4 ' -di chl oro-2-methyl acryl an i 1 i de
N-(3-chloro-4-methylphenyl)-2-
methyl-pentan amide


700
500
148

8-9
8-9

vapor
Pressure
mm Hg 20-25
C (xlO-6)
0.5

3.0



15

0.4







0.07

0.02









Parachor
470

473

479

499

513

539

569

599

592

634

HOC
486
446
626

474
566


-------
  TABLE 3-42.  (CONTINUED)
Common
Name or
Designation
Phenyl amide
Diphenamide
Thiocarbamates
EPTC
CDEC
Pebulate
Vernolate
Cycloate
Butyl ate
Carbothioate
Molinate
Trade
Name
Enide
Eptam
Vegadex
Til lam
Vernam
Ro-Neet
Sutan
Ordram
Chemical Water
Name Solubility
20-25C,Ppm
N,N-dimethyl-2,2-diphenylacetamide
S-ethyl dipropylthiocarbamate
2-chloroallyl diethyl-dithio-
carbamate
S-propyl butyl ethyl thiocarbamate
S-propyl dipropylthiocarbamate
S-ethyl -N -ethyl thi ocyc 1 ohex ane-
carbamate
S-ethyl diisobutylthiocarbamate
S-ethyl hexahydro-1-H-azepine-
260
370-375
92
90-92
90-109
85-90
45
800-912
Vapor
Pressure
mm Hg 20-25
C (xlO-6)
20-34
2.2
4.3-4.8
5.4-10.4
2.0-6.2
13
5.6
Parachor
581
482
500
522
522
532
562
455
1-carbothioate

-------
     Weber (1972) discusses each family of compounds  in  detail.   Chlorinated
hydrocarbons are insoluble in water (< 1 ppm) except for lindane.  DDT is the
most studied  compound  in  this  family; it  is the  least  soluble, and  it  is
highly immobile in  soils  (Weed  and  Weber 1974, Grau and Peterle 1979).  DDT is
also very persistent  in  soils  (half-life is 10-20 years).  The other compounds
are less  persistent  than DDT,  but still  relatively  immobile  (Harris  et al.
1969).

     Organophosphates are more  soluble and more  volatile  (higher  vapor
pressure) than  chlorinated hydrocarbon.  These  compounds  are more degradable
than chlorinated hydrocarbons.   The mobility of organophosphate is  directly
related  to  solubility  (King  and  McCarty 1968,  Fuhremann  and  Lichtenstein
1980).    Organophosphate  still   is  considered  to be immobile  in  soil  systems
(Harris 1967,  Jenkins et  al.  1978).


Quantitative Description  of Adsorption


    Adsorption  can  be  described  in  two  ways:    1)  adsorption  equilibrium,
and 2)  adsorption kinetics.   The first approach is based  on  the assump-
tion that the  adsorption process is instantaneous, i.e.,  equilibrium  is
achieved  in  relatively  very short  times.   The  second  approach   is  based  on
the assumption  that  adsorption  is  a  time  dependent process.    The  quanti-
tative description  of adsorption,  when coupled  with  a transport  equation,  is
important in  assessing  the fate of  pollutants  in  soil   systems  as  discussed
previously.    Travis and  Etnier  (1981)  have reviewed   available  adsorption
models,  which are summarized  in  Table 3-43.   Some of the  models will  be
described in this section.

Adsorption Equilibrium--
    Equilibrium  adsorption  is  described  by  an  adsorption  isotherm,  which
is the  relationship  between  the amount of  solute  adsorbed  and  the  equilib-
rium concentration  of solute in  the  soil  solution.   Isotherms can be divided
into four general types  according to Giles  et al. (1960) and are presented in
Figure 3-39.   The  L-type curve, also known  as  a Langmuir  type  curve,  occurs
when there is  no strong competition from the solvent for sorption sited on the
adsorbent surface.   The  S-type curve shows  an initial  slow rate of adsorption
at low concentration.  The rate of adsorption increases  as the concentration
increases.   The C-curve  is  applicable where  constant partitioning  occurs
between solution and  adsorbent  phases.  Finally,  the H-curve  is  applicable
where  there is a very high  affinity of the adsorbate for  the adsorbent.
Chemisorption,  for  example, usually  produces  an  H-curve  adsorption  isotherm.
H-type isotherm has been  observed for diquat  (6, 7-dihydrobipyrid) (1.2-a:2-,
1-c)  pyrazidinium  dibromide)  and  paraquat  (1,1-  dimethyl-4,  4-bipyridinium
dichloride)  on  Na-montmorillonite  and Na-kaolinite  clays  and for  promotone
on H-montmorillonite  (Weed and  Weber 1974).   Examples  of  H-isotherms  for
some pesticides obtained  from Weber (1972) are shown in Figure 3-40.

     Specific   adsorption  isotherms  that  are  used  to  describe  immobiliza-
tion of  organic constituents in  soils include the  following:    1)  Langmuir
isotherm,  2)  Freundlich  isotherm,  and  3)  Brunauer,  Emmet  and  Teller  (BET)
isotherm.


                                     125

-------
 TABLE 3-43.   EQUILIBRIUM AND NONEQUILIBRIUM MODELS (TRAVIS AND ETNIER  1981)
                  Used by permission, see Copyright Notice


1.0  Equilibrium sorption models
     1.1 Langmuir isotherm

              K,  K7  C
         S = T
               + K2 C

     1.2  Freundlich isotherm

          S = KCN     (nonlinear)

          S = KdC     (linear)

     1.3  BET isotherm


          s ,	BQ
              (Cs - C) [1 + (B - 1)(C/CS71


     1.4  University phosphate adsorption

          S = ac + X0                      C ^ Cc

          S = ac + KCN                     C <_ Cc

          where Cc = (X0/K)1/N

     1.5  Langmuir two surface isotherm


               kl  bl  C       k2  b2  C
          O  "^^^^T it  f\   *  W .  *   f+
     1.6  Competitive Langmuir

          (Ci/C2)/S = (b2/ki bi) + (Ci/b2 C2)

2.0  Nonequilibrium sorption models

     2.1  Reversible linear
     2.2  Reversible nonlinear
             =   _  c  . k  S
          dt     p   L    K2
                                      126

-------
                       TABLE 3-43.  CONTINUED.
2.3  Kinetic product model

     dS _   rb d
     dt ' a C S

2.4  Bilinear adsorption model

     || - kxC(b - s) - k2s

2.5  Mass transfer model

     || = K(C - C*)

2.6  Elovich model

     || = Aj_ exp(-B2 a)

     q = fraction of adsorption sites  in soil matrix covered  by
         solute

2.7  Fava and Eyring model


        = Zktf)  sinh(b<{>)
     S(0) and S() are the initial amount sorbed and  amount
     sorbed at equilibrium respectively.

2.8  Two site kinetic model
     SI
     f denotes fraction of sorption sites occupied which  are
     type 1.
                                 127

-------
                   V
                   O
                   in
                   E
                   <
                                                          H
                          Equilibrium Solution Concentration
Figure 3-39.   Classification of  adsorption isotherms  (Giles et al.  1960,
               by permission, see  Copyright Notice.
                                                              Used
10O
CT
8
80

60

4O'

20
E
< 0

*" ""*  Diq & Paraq
^ o Hyamme
' J.-"^ * Me Bt
'  	 "" 7?  * Pnen Cl
f^ -*"~ O Pnospnon
^  Pyr Pyr Cl
o Et Pyr 8r


 34567

turn Concentration (X10 )

O1
o
o
V
E
I
a
i.
o
wi
o
<

c
o
E
<
5O


40


3O

20

10

i
0




-Hyamme
| -Pnen Cl
_---'D * rMe B>

,- 'f^-^~A~~ " "~ * r-Pnospnon
'//^ \ r-^'Q ^ Paraq
'/ 	 O m 	 lP_ | i-Pyr Pvr Cl

3 ^ 	 	    * " <^^ t Py r 8 r
x'"  - -"" ~~~ "~~ ^^>

                                                 2   3   <   5   6    7   8

                                               Molar Equilibrium Concentration  (X10~*)
                                                                10
          Equilibrium  C oneentration (X10 )
Figure 3-40.   Isotherms for adsorption  of several cationic pesticides on  (top)
               Na-montmorillonite,  (center)  Na-kaolinite,  (bottom) soil  organic
               matter (Weber 1972).  Used by  permission,  see  Copyright  Notice.
                                        128

-------
     1) langmuir isotherm:   originally  this isotherm was  developed  for
adsorption of  gases  by solids.    The derivation was  based  on  three  assump-
tions:   1) constant energy of adsorption,  i.e.,  independent  of the extent of
surface covered, 2) no interaction between adsorbed molecules,  and  3)  only a
monolayer  adsorption  is formed on  the solid surface.   The Langmuir adsorption
equation may be expressed  as:

          K- K9 C
where S  is  the  amount of adsorbed solute per unit mass  adsorbent,  Kj  repre-
sents the maximum  amount  of  solute that can be adsorbed by the  soil matrix,
l<2 is  a measure  of the  bond  strength  holding  the  sorbed  solute on  soil
surface, and  C  is the equilibrium concentration  in  the soil  solution.   The
Langmuir isotherm  has  been used extensively (e.g.,  Cavallaro and  McBride 1978)
for organic  and  inorganic  constituents.

   2)  Freundlich  isotherm:  The Freundlich isotherm is expressed as:

     S = KCN                                                           (3-28)

where K  and  N  are constants.    This isotherm  was  an  empirical  formulation
which was  used to describe gas  adsorption on solid phase.   However,  the
Freundlich   isotherm  was  derived  by  Halsey  and  Taylor  (1947)  based  on  the
assumption  that the  heat of adsorption is a  logarithmic function of  the
surface  covered.  The  Freundlich isotherm has  two  important properties.
The first is  that  the Freundlich  isotherm  is a  very flexible  equation.   Con-
sidering the flexibility  of  two  parameters,  the  isotherm can  fit a wide range
of data.  The second  property  is that the Freundlich  isotherm  does not  have
a maximum limit  for the amount of  substance sorbed.  Due to the flexibility of
this Freundlich isotherm  it  is  used  extensively and  has been proposed  to be
used with a  transport equation  to describ the movement  of synthetic  organic
chemicals (pesticides) in  soils (e.g., Van Genuchten et al . 1974).

     The linear isotherm  is an important  isotherm which- can  be  obtained  from
the Freundlich isotherm when N = 1.   The linear isotherm has been used  for low
concentration of  pesticides  because  of  the  available  analytical  solutions
when coupled  with  a transport equation  (Kay and  Elrick  1967,  Green  et  al .
1972, Davidson et  al .  1968, Davidson and Chang 1972,  Hugenberger et al . 1972,
and Davidson and McDougal  1973).   The linear isotherm  may be expressed  as:

     S = kdC                                                           (3-29)

where Kd is  called the  distribution  coefficient.   This  isotherm  can also be
obtained from  the  Langmuir  isotherm  (Equation  3-15)   if  it  is  assumed  that
K2C1,  in which case  Kd = KjKj.

     Under  normal   soil moisture  conditions,  with  sorption constants  greater
than one  (e.g., usually  for  nonionic  compounds), most of  the  chemical  is
present  in  the  soil system  in  an  adsorbed state.   The  percent  sorbed  can be
expressed in terms  of  K
-------
where 9 =  soil moisture  content  (weight  basis,  assuming density  of  water as
1.0 g/cc).   Figure  3.41 illustrates the extent  of sorption (percent sorbed)
as a  function of distribution  coefficient  K^  for different values  of 0.
Hamaker and Thompson (1972) point out that this explains the observation that
chemicals  tend to resist leaching  and  remain  in  the upper soil layers longer
than would be expected  based  on chemical  solubilities.

   These observations have important implications with respect to management/
treatment  of hazardous  waste  contaminated soil.  Careful control of soil water
content will  determine,  to a large extent, the  relative  immobilization of a
given set of  chemical  constituents  identified  at  a remedial  site.  Optimiza-
tion  of cost effective and efficient treatment may require a compromise
between optimum  soil moisture content for  biodegradation  versus adsorption.
Implications for  specific treatment  methods are discussed in detail in Chapter
2, Volume  I.

     The K  or Kj value  is dependent on  the  type  of  soil,  even  for  the same
chemical.    Koc,  the  normalized coefficient  of  adsorption  with respect  to
organic carbon content  (OC),  is defined as:

                  x  100  for linear isotherm                           (3.31)

     KOC = K/OC%  x  100    for nonlinear Freundlich  isotherm             (3.32)

The Koc parameter is less variable  than the original coefficient of adsorption
and  is  nearly independent  of soil  type  (Hamaker  and  Thompson  1972,  Rao and
Davidson 1980, Kenaga and Goring 1980,  and Karickhoff  1981).  Thus the impli-
cit  assumption is  that  the  organic matter content plays  the most  important
role  in adsorption of organics by soils.    If this  assumption  is not true, the
KQC  will  be dependent  on  the  mineral  content of soils as well.   Also, the
argument does  not  hold for soils with very low  and very  high organic carbon
contents (Hamaker and  Thompson 1972, Rao and  Jessup '1982).  Koc values for a
multitude of organic compounds are  listed  in several publications  (Hamaker and
Thompson 1972, Kenaga and Goring 1980,  and Karickhoff  1981).  Recently it has
been  reported  that  Koc is  also  independent of  soil fractions i.e.,  particle
size  separates (Karickhoff  et  al.  1979,  Rao et  al.  1982,  and Nkedi-Kizza
et al.  1983).

   Due  to  the large number  of  toxic  organic substances  contaminating soil
systems, it is impractical  to measure adsorption constants  for  all substances.
Hence,  indirect measurement of adsorption  constants by relating  them to
properties  of the  specific compound appears to  be efficient  and economical .
Lambert  (1967) has  derived  a relationship  between  adsorption  by  soil  and
chemical structure of certain classes of  chemicals. The relationship  is based
on  extrathermodynamic  linear free  energy  approximations  and  uses "parachor"
(p)  as  a  measure  of  the  molar  volume  (V)  and  surface   tension (r)  of the
chemical  under investigation:    p   = Vmr^/^.   Two assumptions  were  made in
this model:   1) the soil organic  matter is  the  dominant sorbing medium,  and 2)

                                      130

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Q
LU
QQ

-------
the adsorbate molecule is an uncharged molecule.   Because  of difficulties in
measuring  parachor  for  pesticides,  this concept has not  been thoroughly
investigated  (Rao and Davidson  1980).   Recently there have  been some attempts
to  correlate  Koc  with  solubility and  octanol-water  partition  coefficient
(Kow)   if  a compound  (Karickhoff  et  al .  1979;  Karickhoff 1981; Kenaga  and
Goring  1980;  Schwarzenbach  and  We stall  1981;  Chiou et al .  1982).   Briggs
(1981)  has demonstrated  both  theoretical  and  experimental  justification  for
such relationships.   Table 3-44  summarizes these relationships.

     As shown  by the  equations  in  Table 3-44,  Koc values  are correlated
with octanol-water partition coefficients (Kow).  The Kow values were general-
ly measured by direct liquid-liquid partitioning.   However, recently Veith et
al . (1979)  and   Ellgehausen et  al. (1981)  have used  the  retention  time  of
constituents  in  high  performance  liquid  chromatography (HPLC)  for estimating
Kow.   Veith  et  al .    (1979) obtained  a calibration curve  using  a mixture of
standard chemicals.   The average variation  of  the  calculated K0w's  fr  18
other  chemicals  was  22.5 percent,  which  is  comparable to other methods  of
estimating Kow.  Laboratory measurement of  Kow is often  highly variable
(Mingelgrin and  Gerstl  1983, and Baes  and Sharp  1983).

     Sabljic  and  Protic  (1982)  have  used  molecular  connectivity indices  to
predict Koc.   Molecular connectivity indices  are  numerical  characteristics
of  a  molecule depending  on  the number and  types  of atoms  and  bonds  and  the
adjacent environment.  Polycyclic  aromatic hydrocarbon  data  was  used  in this
study, which  was developed by Karickhoff et al .  (1979).

     3.   Brunauer,   Emmet,  and  Teller  (BET)   adsorption  isotherm:    The  BET
adsorption theory  is  actually  an  extension of  Langmuir monol ayer adsorption
theory.   The BET model  assumes  that the  Langmuir equation applies  to each
layer  adsorbed.   Also, it assumes that  the  first layer need not be completed
before  another layer  can  start.   The BET equation may be expressed as:

                    BCQ

      S =
          (cs  - e)  LI + (B-l)(c - cs)J

where cs  is  the  saturation concentration of the  solute,  c  is the concentra-
tion of  the  solute in liquid  phase,  Q  is the number  of moles adsorbed per
unit weight of  adsorbent in  forming a complete surface  layer, qe  is the
number of moles of solutes adsorbed per unit weight at  concentration c, and B
is  a constant.   The BET  isotherm  has  been  used  for adsorption of pesticides
(Jurinak 1957).

    The  isotherms  discussed  above  can be  presented graphically  as  straight
lines using convenient transformations (Figure 3-42).   More models are avail-
able and are listed in Table  3-43.

Nonequilibrium Adsorption--
     The  summary of kinetics  models  available are shown  in Table  3-43.   A
detailed discussion of the kinetic equations is given by  Hamaker  and Thompson
(1972)  and  Travis and  Etnier  (1981).   The relevant  kinetic  models  will be
discussed  in  conjunction  with  transport  models  in  another  section  of  this
report.


                                      132

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TABLE 3-44.  Koc RELATIONSHIPS WITH SOLUBILITY AND OCTANOL-WATER PARTITION
                                  COEFFICIENT
1.  Karickhoff et al. (1979), for the polycyclic aromatic class of
    chemicals
    log Koc = 1.0 log kow - 0.21                                    (1.1)
    log Koc =-0.54 log Xsol + 0.44                                  (1.2)
    where Xsoj is water solubility expressed as a mole fraction
2.  Karickhoff (1981) obtained from data for five polycyclic hydrophobic
    compounds (benzene,  hapthalene, phenonthrene, anthracene, and pyrene)
    log Koc = -0.921 log Xsoi - 0.00953 (MP-25) - 1.045             (2.1)
    log Koc = -0.594 log Xsol - 0.197                               (2.2)
    log Koc =  0.987 log Kow - 0.336                                (2.3)
    where MP is melting  point ("C), if liquid at 25C  MP = 25
3.  Chiou et al.  (1979)
    log KOM = 4.04 - 0.557 log WS                                   (3.1)
    where WS is solubility in ^mole/1
4.  Chiou et al.  (1982)
    log KoM = -0.813 log (SV) - 0.993                               (4.1)
    log KoM = lfl.729 log (S)                                         (4.2)
    where S is solubility in mole/1 and 17 is the molar volume (I/mole).
5.  Kenaga and Goring (1980)
    log Koc = 3-64 - -55 1o9 ws                                    (5.1)
    where WS is the  solubility in mg/1
6.  Schwarzenbach and Westall (1981)
    log Koc = 0.72 log Kow +  0.49                                   (6.1)
                                      133

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1/S
          l/  C
                      logS
                           flog K
log C
       a.  Langmuir            b.  Freundlich

Figure 3-42.  Linear transforms of adsorption isotherms.
                        c.  BET
Factors Affecting Sorption

     It was  stated  previously  that  adsorption is a complex  process  involving
the  interaction  of a  solvent,  solute, and  adsorbent system.   Hence,  it  is
expected that  the properties of  the solvent,  solute,  and  asorbent  will  in-
fluence  the  adsorption  process.    Bailey and  White  (1970,  and Hamaker  and
Thompson (1972)  have  discussed  in detail  the various factors  that  influence
adsorption.  In this section the  factors  important  for  predicting  sorption of
hazardous constituents on soil  are highlighted.

     Characteristics of the adsorbate that affect adsorption are:  1)  chemical
character,  2) dissociation constant, 3) water solubility,  4) charge  distribu-
tion of organic cation, 5) molecular size, 6)  polarity,  and 7) polarizability.
These factors relate specifically to the following aspects of sorption:

     1.  Th'e mechanism by which the  adsorbate  will be  adsorbed (e.g.,  hydrogen
         bonding vs. ion exchange).

     2.  The effect of pH on adsorption and reversibility of of adsorption.

     3.  Location of adsorption, in  other words exterior  surface vs. inter-
         layer surface of clay mineral.

     4.  Orientation of molecule with respect  to adsorbent surface.

Characteristics of  a  chemical  such  as  parachor,  solubility, and connectivity
index have been used as mentioned previously to determine adsorption  constants
(Lambert 1967,  Karickhoff et  al.  1979,  Chiou  et al. 1979,  Karickhoff 1981,
Chiou et al. 1982, and Sabljic and Protic 1982).

     The physicochemical  characteristics  of  adsorbents  that affect  adsorption
are  mainly related to  surface characteristics.   That  is  the  surface area,
                                      134

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shape,  and  charge  (magnitude  and  distribution)  of the  adsorbent  surface.
The colloidal  part  of soil  is  important  due to its  high  surface area.   The
colloidal part consists  of clay minerals, organic  matter  and hydrated metal
oxides.

     Clay minerals  are  minerals  with  sheet silicate  structures.    A layer
silicate may  be  a combination  of two  types  of  structural  units.  The first
unit  is  a  tetrahedral sheet  which  is  an  Si'4+  atom  joined  with four  oxygen
atoms  forming  a tetrahedron.   The  second  structural  unit  is an octahedral
sheet  with  an Al3+  (typically) in  octahedral   coordination  with six  oxygen
atoms  or hydroxyl  anions.   The relative  proportions of the  two sheets  de-
scribes the clay type.  A 1:1 clay  (e.g.,  kaolinite)  has low  specific  area  and
low cation  exchange capacity (CEC).   The adsorption  in 1:1  clay occurs only on
the external  surface  area.  A  2:1  expanding clay (e.g., montmorillonite  and
vermiculite) has  high specific  area  and high CEC.   Adsorption  may occur
between  the layers as  well  as on  the external surface.  The  organic  molecule
should have some polarity  in  order  to  penetrate the  basal plane  (between  the
layers).  Organic molecules adsorbed  between  the  layers  might  not  be available
for biodegradation  (Weber   and  Scott  1966).    Other  2:1 clays  that  are  not
expandable  due to strong  bonds between  the layers (e.g., illite and chlorite),
have  lower specific area and  lower  CEC.  Table  3-45 has a summary of proper-
ties of  different clay minerals obtained  from Bailey and White (1970).  Clay
minerals have a net negative charge which is  the result of  isomorphic substi-
tution (Bonn et al.  1979).   The charge  induced by isomorphic  substitution is  a
permanent charge  and   is independent of pH.    The magnitude  and  location  of
this charge is important  in attracting  cations to clay surface.

     Soil organic matter (OM)  is  a  complex  mixture  of organic   compounds  in
soil.   Qualitatively OM consists of two fractions, humic and  nonhumic.  Humic
organic matter is the  transformed (microbiologically  or chemically) component
of plants,  animals, and microorganisms.  Humic organic  matter  is  divided into
three  components: 1)  fulvic acid,  2)  humic  acid,  and  3)  humins.  These  are
similar  in structure but rather different  in molecular weight and functional
groups.  Nonhumic  organic  matter  is represented  by the unaltered remains of
plants,  animals,  and  microorganisms  such   as  cellulose,  starch,  proteins,
chitin, and fats (Bohn et  al.  1979,  Morrill  et al.  1982).  Soil  OM generally
has high  CEC,  however,  the CEC is  pH dependent (Bohn et al.  1979).   Many
reseachers  consider  soil  OM the most  important parameter for  pesticide adsorp-
tion (Sheets et al .  1962, Roberts and Wilson  1965, Hamaker et  al.  1966,  Savage
and Wauchope  1974,  and Nkedi-Kizza  et  al. 1983).   Also it has been  reported
that desorption  of  organic compounds  from soil  OM  is  slower than  that from
clay minerals (McGlamery and  Slife 1966;  Helling  et al .  1971;  Jamet  and
Piedallu 1975).  Desorption is not  complete   if  soil  is allowed   to  dry after
adsorption  (Hamaker and Thompson 1972).  Walker  and Crawford  (1968) showed  an
absolute increase  in  adsorption of four  triazine herbicides  when  straw  was
added  to soil.   Their  study was performed on 36 different soils.  Also, they
found   a  high  correlation between adsorption and present organic carbon   for
soils   with  percent  OC>5.   Thus the  implications of enhanced adsorption  of
hazardous constituents by adding a source of organic matter to the soil such
as  straw is  important in   terms  of "immobilizing"  the contaminants  of   the
soil .
                                      135

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        TABLE 3-45.   SELECTED  PHYSICAL  PROPERTIES  OF  SOIL CONSTITUENTS
                           (BAILEY AND  WHITE  1970)
                   Used  by permission,  see Copyright  Notice
                                                  Physical Property
Soil constituent                      Cation exchangeSurface  area
                                       capacity                  (sq. m/g)
                                       (meq/100 g)
Organic matter
Vermicul ite
Montmorillonite
Dioctahedral vermiculite
11 lite
Chlorite
Kaolin ite
Oxides and hydroxides
200 to 400
100 to 150
80 to 150
10 to 150
10 to 40
10 to 40
3 to 15
2 to 6
500 to 800
600 to 800
600 to 800
50 to 800
65 to 100
- . 25 to 40
7 to 30
100 to 800
     Amorphous  minerals  are non-crystalline  metal oxides and hydroxides
(mainly Al  and  Fe).   These  minerals represent  the  transition  stage between
unweathered  parent  materials  and well  crystallized  secondary soil  minerals.
The CEC of  amorphous mineral  is pH dependent.   The charge  for freshly de-
posited mineral  is  positive which  becomes  negative  with aging.   The positive
charge plays an  important  role in anion  adsorption (Bohn et al. 1979).

Nonsingularity of  Adsorption-Desorption--
     The adsorption  isotherms  described are obtained  by implicitly assuming
that the adsorption  is  a  reversible  process.   However, in some cases adsorp-
tion is not reversible.   That is,  the desorption path will be different from
that of the adsorption path.    Nonsingularity  (hysteresis)   is  defined when
there is a  residual  retained  on  soil  at a given equilibrium  concentrate when
desorption  occurs  (Rao and  Davidson  1980).    Desorption  has  been observed
frequently (Hornsby and  Davidson  1973,  Swanson and Dutt  1973,  Farmer and Aochi
1974,  Savage and Wauchope  1974).   Hornsby and  Davidson (1973) found that the
desorption distribution  coefficient is  a function of  the amount adsorbed prior
to desorption.  Desorption generally follows the Freundlich isotherm equation
but with a  different coefficient.   The desorption  exponent (Na) was equal to
the adsorption coefficient divided  by 2.3 (Swanson  and  Dutt  1973).  Rao and
Davidson (1980)  gave three reasons for non-singularity:  1) artifacts created
due to  some aspects of the  desorption method  used,  2)  failure to establish
complete  equilibrium  during  the  adsorption  phase,  and  3)  chemical   and/or
biological  transformations of pesticides  during  the experiment.   Koskinen et
al . (1979)  have studied  the  desorption  of  2,4,5-T. They noticed  that non-
singularity  increases  as  the equilibrium  time  allowed  for  adsorption  in-
creases.  Also, they found that when  concentrations were corrected for bio-
degradation, which  they monitored by  C02  emission,  the hysteresis (reaction


                                      136

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direction dependence)  was  decreased  considerably.   Shalom  et  al .  (1980),
studied desorption of  12  insecticides,  and  found  desorption was proportional
to the  solubility of  the compound.   They also  noticed  that insecticides
desorbed in decreasing order from  sand,  sandy  loam,  and sediments, while the
relative order of desorption of the 12 insecticides remained the same in each
so i 1.

     Rao and Davidson  (1980) have  shown  the  variation  of error in estimating
adsorbed material when desorption  is  neglected  and  the  following  argument is
taken   from  them.  As  indicated previously,  both adsorption  and  desorption
phases follow Freundlich  isotherm but  with different coefficients:

     Sa = Ka CNa                                                       (3-34)

     Sd = Kd CNd                                                       (3-35)

where  subscripts a,  d  denote adsorption and desorption  respectively.   Since
the degree  of non-singularity  is  dependent on  the  maximum  amount  adsorbed
(5^,)  before desorption  (e.g., Van Genuchten et al.  1974), therefore:

     Kd = K^ Sm"B                                                      (3-36)

where  3 = Nd/Na.  Since Sm can  be expressed using  Equation 3-35 as:


     Sm = KaCma                                                         (3-37)

substituting Sp,  from  Equation 3-37  into Equation 3-36 we get:
              N  -N
     Kd = Ka Cm                                                         (3-38)


Substitution of  Equation  3-38 into  Equation 3-35 for Kd yields:


     Sd = Ka Cma" Vd                                                  (3.39)


Calculating  the  ratio Sd/Sa by  dividing Equation 3-39 by Equation 3-35:

     S,     N -N.   N.-N
    _ _ ir a  dwr  d  Cv
     S2 ' (Cm    )(C      )                                             (3-40)

Using  Na  =  2-3Nd (Swanson and Dutt  1973), and  assuming  that the largest
Cm =  10 mg/1,  Equation  3-40 is  simplified to

    fd . (100.5652 Na)-(c-0.5652 Na)                                    (3_41)


This equation  is plotted  for different  Na values  in Figure 3-43.   From
Figure 3-43 it  is  apparent that the  error  in estimating  the  adsorbed  amount
becomes  larger  as the concentration  decreases,   and  as  adsorption  becomes
a linear function, i.e.,  as Na  approaches 1.

                                      137

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          20
           10
            0.1
                     SOLUTION
  1.O
CON C
10..0
Figure 3-43.   Errors  introduced  by the  assumption  that adsorption-desorption
              isotherms  are singular when  they  are  nonsingular (Rao  and
              Davidson  1980).  Used by permission, see Copyright Notice.
     The  information  presented  here  concerning  processes  and  factors  in-
fluencing adsorption of solute species by  soil  systems  can be used to assess
the relative mobility and  potential  for  immobilization in  a specific waste-
soil  system and  aid  in  determining specific in situ  treatment  schemes.   Ex-
amples and methodologies concerning the use of such information are presented
in the modeling  section  of  this chapter and  in Volume  I of this manual.

SOIL MICROBIOLOGICAL FACTORS  RELATED TO IN  SITU TREATMENT

The Soil Microbial  Ecosystem

Physical and Chemical  Properties--
     The soil  environment  is one of  heterogeneity with  scales of particulate
size ranging from meters to nanometers.  The environment having direct effect
on the biological  activity of  a  single bacterium  or yeast, or microcolony of
bacteria  in  the soil -is  probably no  larger than  a  cubic  millimeter.   The
hyphae  of filamentous  fungi may, however,  interact with a range  of  soil
microenvironments extending over a much  larger volume.   Variations  in water
availability,  soil  atmosphere composition,  inorganic  and  organic  nutrient
availability,  soil  texture, and soil  structure all make up  the environment of
soil microbes and  affect their metabolism  and  growth.  In  a  practical sense,
we are  forced to deal with management  of the soil microbial  environment on  a
relatively large scale,  relying on  the average condition at microsites in the
                                      138

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soil to be conducive to the microbial  function we are  trying to encourage.  We
are, however, more likely to be successful in our approach if we keep  in mind
the nature of  the soil microbial environment and the microsites  of which it
is made.  It is, of course, beyond the scope  of this manual to deal extensive-
ly with soil microbiology or microbial ecology.   Good  textbooks are  available
(Alexander 1977, Atlas and Bartha 1981) if more complete  information on these
topics  is  needed.   Gray  (1978)  has discussed microbial  aspects  of  the soil
relating to pesticide transformations.  We  will also briefly review principles
of soil microbiology which pertain to  the  broader topic  of toxic and  hazardous
waste  transformations,  with  emphasis  on  environmental  factors  and microbial
populations  or  microbial  community structure which might be  manipulated to
accomplish treatment of contaminated soil.

     Soil  microbes  are  greatly  affected  by  soil water.   Water  is of  course,
necessary for  microbial   life and  the water potential  against  which  micro-
organisms must extract water from the  soil  regulates their activity.  The Soil
Science Society of America (1981) has published  proceedings of a symposium on
the relation of  soil .w.ater potential to soil  microbiology.  Many  micro-
organisms are capable of metabolic activity at water potentials lower than -15
bar.   The lower limit for all  bacterial  activity is probably abouth -80 bar,
but some  organisms  cease activities at  -5 bar.   Fungi  appear  to be more
tolerant of low soil  water potential,  than  are the bacteria (Gray 1978, Harris
1981),  and  microbial decomposition of  organic  materials  in  dryer  soils is
probably due primarily  to fungi.   When the  soil becomes too  dry many micro-
organism form spores, cysts, or other resistant  forms, while many others are
killed by desiccation.   Soil  water  also  serves  as  the  transport  medium
through which many nutrients diffuse to the microbial  cell, and through which
waste  products  are removed.  The decomposition  of  pesticides and other xeno-
biotic organic compounds as well  as  natural organic matter in the soil  depends
on  soil  water  potential  and its   influence  on  microbial  activity  (Sommers
1981).

     The degree to which the soil pore space  is filled  with water also  affects
the exchange of gasses  through  the soil.   Microbial  respiration,  plant root
respiration,  and  the respiration of other organisms  removes  oxygen  from the
soil atmosphere and enriches it  with carbon dioxide.   Gasses diffuse into the
soil from the air above it,  and gasses in  the  soil atmosphere diffuse into the
air, but the oxygen  concentration  in  ordinary soil  may be only  half that in
air while carbon  dioxide  concentrations may  be  many times that of air (Brady
1974).  Even so, a large  fraction of the microbial  population within the soil
depends on oxygen  as the  terminal  election acceptor in metabolism.  Bacteria
of the genus Pseudpmonas,  members of which  are often linked to the transforma-
tion  of xenobiotic  compounds in  the soil,  are of this  type,  i.e.  strict
aerobs.  When  soil  pores  become filled  with water,  the  diffusion of  gasses
through the soil is severely restricted, oxygen is consumed faster than it can
be replaced, and  the soil becomes  anaerobic. This  loss  of oxygen  as  a meta-
bolic  electron  acceptor induces  a  drastic change in  the  make  up  of  the soil
microflora.   Facultative  anaerobic  organisms, organisms which use alternative
election acceptors  such  as  nitrate  (denitrifiers)  or sulfate  (sulfate  re-
ducers), and  strict anaerobic organisms become the dominant species.  General-
ly, microbial metabolism  shifts  from  oxidative to  fermentative,  and  becomes
less efficient  in  terms of  biosynthetic  energy production.    Soil structure


                                      139

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and/or texture primarily determine  the  size of  soil  pores, and  hence  the water
content at which gas  diffusion  is  significantly limited in a  given  soil, and
the rate at which anaerobiosis  sets in.

     Soil   texture  and  clay  mineralogy  are  also  important  factors  in   soil
microbial   ecology  (Stotzky 1972,  1980).   Clays  with  a  1:1  crystal  lattice
(e.g.  kaolinite)  are non-swelling  and  have  lower  cation  exchange  capacity,
while  1:2 crystal  lattice clays  (e.g.   montmorillonite)  swell  enormously
trapping  water  and  perhaps other  compounds  between the lattices.   The  high
cation  exchange  of clays  like  montmorillonite greatly  increases  the buffer
capacity  at  microsites  within  the  soil,  reducing  the  impact  of protons re-
leased  into  the  environment as  a  product of  microbial  metabolism.    Differ-
ential  sorption  of  organic  compounds  and inorganic ions, including  hazardous
waste  components by different  clays,  also  affects the  availability of  sub-
strates and micronutrients to microogranisms.   Stotzky  (1980) has investigated
the biodegradabilty of proteins, peptides, and  amino  acids  adsorbed by mont-
morillonite clay and found that  they were much  less  susceptible to degradation
by microorganisms- readily  able  to  use  them  in  solution.   However,  since all
clay in soil  is  apparently  not  complexed with  organic matter, some  mechanism
(mechanical,   chemical,  or biological)  must  remove or  prevent complexing of
clay with  organic  matter in situ.   Perhaps organics  in situ are  not bound
directly to  the  clay but to polymeric hydous oxides of Fe,  Al,  and Mn asso-
ciated with the clay.  Fluctuations in  soil (microsite)  pH would disrupt these
inorganic  polymers, releasing the  organic matter  to solution.   It could  then
either be  degraded  or rebind  to  soil clays (Stotzky  1980).

     Soil  organic matter  is extremely  important  to  the microbial ecology and
activity of the  soil.   Its  high cation exchange capacity and  high density of
reactive functional groups play  important roles  in  the retention of bacteria
in the  soil as well  as binding both organic  and  inorganic compounds  which may
be added  to  the  soil.   These adsorbed  or chemically  bound  compounds or  ions
may be available for  microbial  attack  and  transformation.    This  microbial
activity  may  detach-the compound  or  its metabolite  from the  soil  organic
matter, increasing  its mobility  in  the  soil (Bartha  1980).  Although  generally
considered to be recalcitrant,  soil  organic matter  is in  a  state  of flux.
Mineralization of soil  organic  matter  may provide  important source  nutrients
to the  soil from organically bound nitrogen, phosphorus, and sulfur  (Woodman-
see et al. 1978).

     Due  to  their  high  surface to volume  ratio, soil microogranisms are
well   adapted  to take  up inorganic nutrients  from  the soil.   If biodegrad-
able organic  materials  are added  to  the soil  so  as to raise the  carbon to
nitrogen (C:N) ratio higher  than  about  20:1,  mineral nitrogen in  the  soil  will
be immobilized into microbial biomass,  and  the decomposition process  will be
slowed  considerably.   -Similar  immobilization  of phosphorous  can  occur  when
carbon  is  in  excess (Alexander  1977).   If  during the treatment of  hazardous
waste  contaminated soils, the  soil  must be  managed  to  decompose organic
matter, nitrogen and  phosphorus  may be  required  to bring  the  C:N:P ratio to
approximately  120:10:1,  the  approximate ratio  found  in  bacterial  biomass
(Alexander 1977,  Kowalenko 1978).
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     Soils contaminated  by  waste materials may contain elevated concentrations
of salts.  In addition,  treatment  approaches such as the use of fertilizers or
chemical agents, may add salinity to  the  soil.   Increased salinity increases
the osmotic potential of the  soil water,  and  soil  microbes may be restricted
in their activity due to osmotic stress.  Monitoring of soil salinity prior to
and during treatment is  important to  the  success of any biological  treatment
process.

     The soil reaction,  or pH, affects the  activity of soil  microbes.   Fungi
are typically more  tolerant  of acidic soil  conditions (below pH  5)  than  are
bacteria in  aqueous  media,  but the  differences are  less  clear  in  soil  where
the buffer capacity  of  clay and  humic materials affect  the  concentration of
protons at microsites.    (Gray  1978).   Soils may need to  be limed  to  raise pH
or treated with sulfur or other acid forming materials to lower pH so  that  the
soil pH ranges  between  5.5  and 8.5  to encourage microbial  activity.   Phos-
phorus solubility is maximized  at  pH 6.5; this may be the ideal soil  pH.

     Adsorption  of  organic  molecules on  negatively  charged clay  colloids
strongly depends  on the solution pH.   Critical pH values are dependent  on
the pKa of the adsorbate and  the magnitude of charge on the adsorbent.
Adsorption of pesticides  of  widely  varying molecular  structure on  clays
increases  as  pH decreases  (Frissel  and  Bolt  1962,  Harris and Warren  1964,
Talbert  and  Fletchall   1965).   The  pH effect  is  apparently less  important
for peat and  some other  organic soils which suggests that a different
sorptive mechanism is occurring for those types of soils.

The Bacteria
     The metabolic diversity of the  procaryotic  organisms  in  the soil  focuses
a great deal  of attention on  them when biodegration of xenobiotic or hazardous
materials is  of concern.  In  general, bacteria may be classified metabolically
as heterotrophic; that  is,  they  derive their energy  and  carbon  for  survival
and growth from  the decomposition of  organic  materials,  or  as  autotrophic,
meaning that  they fix the carbon  they  need for growth from carbon dioxide  and
(usually) obtain their energy from light  (photosynthetic)  or  the  oxidation of
inorganic  compounds  (1ithotrophic).    The  heterotrophic  bacteria  are most
important  in the transformation of  organic hazardous compunds,  and soil
treatment schemes may be directed toward  enhancing their  activity.   However
the availabilty of  nutrients (especially nitrogen) to  the heterotrophic
microorganisms of  the   soil  may  depend  on  the  transformation  of  inorganic
materials  by 1ithotrophic organisms  (Focht and  Verstraete 1977,  Painter
1977).  Transformations of toxic metals or metabloids  and  their  compounds  may
directly or  indirectly involve  the  activities of 1ithotrophic or photo-
synthetic bacteria.

The Fungi 
     The fungi   are  eucaryotic microorganisms  which  lack  photosynthetic
apparatus and depend  on  heterotrophic metabolism.  They may be either  filamen-
tous or  uncellular  (yeasts  or  amoeboid),  while some  types aggregate  to form
macroscopic forms such  as  a plasmodium or  fruit-bodies  (mushrooms).   Fungi
constitute a  large fraction of  microbial biomass in soil, especially in acidic
soil,  and  their  enzymatic  activity  is important  to most  decomposition pro-
cesses.   When levels of  available substrate are  low or  water  availability is


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low, a major portion of the fungal biomass in soil is either dormant or dead.
Fungal  spores or other resistant structures  can  survive in soil  under adverse
conditions for long periods of time,  and then quickly germinate and grow when
conditions become  favorable.    Clay  mineralogy,  temperature, and  other  soil
environmental conditions affect the speciation and diversity of  fungi  in  the
soil.  Most filamentous fungi  are aerobic, and yeasts are often facultatively
anaerobic.  Most fungi  are  mesophilic, and even thermophilic fungi do not grow
above about 65C.   Many fungi  grow at temperatures below 10C.

Algae--
     The soil surface  usually contains  appreciable  populations  of eucaryotic
algae and cyanobacteria.  Since  the zone of light penetration into the soil  is
severely restricted, the algal  biomass  in soil  is  usually low.   Algae may be
important,  however,   in  enhancing  photodecomposition of hazardous  organic
compounds at the soil  surface.

Higher Life Forms--
     The  soil  also contains  many other higher  organisms  which graze  the
bacterial or fungal populations, or feed on detrital matter and its associated
microflora.   Protozoa,  nematodes, insects,   and worms are important  in  this
regard.    These  organisms  affect  the   decomposition  process by  controlling
bacterial or fungal population size through  grazing (Bryant et  al . 1982),   by
harboring microbes within their intestinal tract  which  may decompose a
compound of  interest, by comminuting plant materials  (insects),  or by mixing
the soil and contributing to its aeration.

Microbial Interactions
     Interactions  between  microorganisms  in  the  soil  are complex,  and  un-
doubtedly play an  important role  in  the activity  of microorganisms important
to the transformation or decomposition  of hazardous waste compounds.   Some of
these  interactions  have already been  suggested  in earlier discussion.   Com-
petition for growth  requirements among microorganisms  is intense.  Many
microorganisms  are metabolically specialized  (e.g.,  the  autotrophic  nitri-
fiers)  and  are  less  reliant  on  preformed  organic substrates  and/or  growth
factors.   However  the  nutritional  requirements of  many soil  microbes overlap
to some  degree,  and  those  organisms  which are to  survive in  the soil  must be
able to effectively compete with their neighbors for these required nutrients.

     To  increase  their opportunities  for survival  in the  competitive  soil
environment,  many microorganisms  have  aquired  antagonistic abilities  with
which  they may   limit  the  growth  of  other  microorganisms.   The  antibiotics
produced by soil microorganisms are probably the best known microbial antago-
nistic agents, but other kinds of inhibitors,  including acids, bases and other
inorgranic compounds are used  (Alexander  1971, Atlas  and Bartha   1981).
Suppressive  influences .are often  expressed  between microorganisms and higher
life forms in the soil as well (Rice  1974).

     Soil microbes may also be closely associated  with one another physically
and/or  metabolically.   True  mutualistic or symbiotic  relationships  exist,
where  the organisms  relationships  are necessary  to  their  survival  in  the
niche  they occupy.   Less   restrictive relationships  are  perhaps more common.
It  is  not uncommon  for the degradation of  a xenobiotic  compound  to involve


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sequential  metabolism by two or more microorganisms (Beam and  Perry  1974);  a
relationship which may benefit only one partner (commensalism)  or both (proto-
cooperation or synergism)  (Atlas and Bartha 1981).

Life on the Verge of  Starvation
     Readily assimilable  substrates are short lived in  most soil environments.
The majority  of  time, carbon and  energy  supplies are limited  and microbial
growth rates  are restricted.   Soil  organic matter, including  many hazardous
waste components,  is  recalcitrant  to microbial  attack  and  supplies carbon  and
energy slowly to the  soil microbial ecosystem.   Organisms able to survive  in
such a growth  limited environment must have evolved strategies  which compen-
sate for this  state  of  affairs.   Two  major kinds of  survival  strategies  are
apparent in the microbial  ecosystem.   Winogradsky (1949)  observed,   in  about
1924,  that soil  harbored a population  of bacteria  which increased their
numbers rapidly when   a readily "fermentable" substrate was  introduced to  the
soil.   These  "zymogenous"  organisms would  dominate the population until  the
added substrate was  depleted,  and  then  would die  away.  Another population  of
"autochthonous" bacteria  grew much more slowly, and their population  did  not
change  significantly  when  a  fermentable  substrate  was  added.   Population
ecologists  often classify organisms  which depend  on  high  growth  rates  for
competitive advantage  as "r"  strategists.   This type  of organism would
correspond  to  Winogradsky1s  zymogenous bacteria.   Organisms which reproduce
more  slowly and have many competitive  adaptations  are classified as "k"
strategists,  implying  that their growth is related to the carrying capacity of
the  ecosystem.   These  organisms  correspond  to  Winogradsky's  autochthonous
bacteria (Atlas and Bartha 1981).

     The inoculation  of hazardous waste contaminated soils  with  microorganisms
selected for  their ability  to  degrade  or transform hazardous materials is  a
very attractive treatment concept.   However,  the  treatment manager  must  be
aware that  the restrictive environment  and  complex  ecology of the soil micro-
bial  system  may limit  the ability of introduced microbes  to become  self-
perpetuating and perform  their  specialized functions  for more than   a  short
period of  time.  Reinoculation  may need  to be repeated several  times before
satisfactory levels of treatment are achieved.  Liang  et  al. (1982) conducted
experiments on the  survival  of  antibiotic   resistant  microorganisms  after
inoculation into  sterile  and nonsterile water,  sewage,  and  soil.  They suggest
that microorganisms  which are tolerant of  multiple kinds  of stresses (e.g.,
abiotic  stress,  starvation,  and  antagonism) have  a higher  potential for
survival  in the soil   after genetic manipulation  (engineering)   in the labora-
tory, than  do  microorganisms  with less tolerance  versatility.   Much of  the
current genetic  engineering  work  directed at  producing  bacteria capable  of
complete degradation  of   xenobiotic  compounds is  being  done  with   bacteria
(e.g.,  Pseudomonas)  which  are zymogenous (Chakrabarty 1982).   It is en-
couraging  that some  recent  isolations  of xenobiotic degrading  bacteria have
turned out to be Arthrobacter spp.   These organisms  were isolated using
chemostat  technique!whichallow  time for  more  slow  growing, autotrophic
bacteria to become dominant  and their degradative  ability  to be recognized
(Stanlake  and Finn  1982).   Recently  reported  experiments have shown the
potential   for  use  of these  more  autochthonous  bacteria  to treat hazardous
waste contaminated soils  (Edgehill  and  Finn 1983).
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Biogeochemistry of Toxic  Metals  and Metalloids

     Arsenic,   barium,  cadmium,  chromium,  lead,  mercury,  nickel,  selenium,
silver, thallium,  and  vanadium  and/or one  or more  of their  compounds  are
listed as  hazardous  waste constituents  by the  U.  S.  Environmental  Protec-
tion  Agency (40  CFR 261).   The toxic  nature  of  these  elements or  their
compounds  adversly affects some fraction  of the microbial  population when the
soil is contaminated, while other organisms or  groups of organisms may be able
oxidize,  reduce, methyl ate,  demethylate or otherwise transform these elements
so  that  their  solubility,  sorption,  or  volatility in  the  soil  is  greatly
affected.

Arsenic--
     Since arsenic exists  in  the  -3, +3, or +5  valence states it is subject to
oxidation  and reduction by microbial  activity.   The positive trivalent state
is generally the most toxic (Zajic 1969).  There  is no evidence that organisms
which oxidize arsenite  to arsenate  use the energy available from the reaction
for growth.   Apparently, the  oxidation  is  done  by heterotrophic  organisms.
Many heterotrophs  can also reduce arsenate (Alexander 1977, Zajic 1969).

     Arsenic can be  lost  from soils as volatile  arsine or as methylarsines.
Cheng and  Focht (1979)  studied  the  volatilization of  arsenicals from  flooded
soils amended with glucose and  urea  in  aerobic flasks.   They found that soil
treated with  arsenate  or arsenite gave off  arsine, while soil  amended with
disodium  methylarsonate gave off arsine and  monomethylarsine, and  soil
amended with  dimethyl arson ate  (cacodylic  adic) yielded  arsine  and dimethyl-
arsine.   No  evidence was found for methyl ation of  any  of  the arsenical sub-
strates in the three  soils tested.   Apparently, demethylation was more impor-
tant under these conditions.    Other  studies  (Cox and  Alexander 1973,  Woolson
and Kearney  1973,  Kaufman 1974,  and Woolson 1977)  have found methyl ation of
arsenical s as  an  important  process in soils,  and have also  found  that tri-
methylarsine is an important  gaseous  product.   These results  suggest that
soils  contaminated with   arsenic must  be  managed to  minimize volatilization
through microbial  reduction.   Hassler  (1982)  found  that  essentially only
soluble arsenic was volatile  in  soil and processed oil shale.

Barium
     Although  barium  is  distributed in biological  systems in comparable
amounts with  strontium,   very little  is  known  about  its interactions with
soil microorganisms (Zajic 1969).

Cadmium
     The  growth of soil   bacteria is  retarded  by cadmium, and  the community
structure is  affected.   Cells of Escherichia  coli  exposed  to Cd  suffer
single stranded breakage  in  their deoxyribonucleic  acid (Mitra and Bernstein
1978).  In  experiments  with  bacteria isolated from  Cd  contaminated  soils in
Great Britain, Shearer  and Olson (1983) found that the bacteria would grow in
media containing  lOppm Cd (regardless of chemical  species tested),  but that
growth rate was inversely proportional to  Cd concentration  (0, 0.1 and 10 ppm)
in  a  defined  growth medium.   Chemical  species  of Cd tested were toxic to the
bacteria  in the order:  Cd2* > Cd aspartate > Cd3  (PO/{)2 > Cd3 (PO^s.  Tripp
et  al. (1983)  isolated 50 strains  of  bacteria  on media containing 0,  10, and

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100 ppm  Cd  from six sewage  sludge  amended  sites in England.   Gram negative
bacteria were most common on  the  100 ppm  medium, and  the number of genera of
bacteria decreased with  increasing  Cd concentration.   The number  of genera
isolated on  cadmium medium was significantly lower from sites not contaminated
with cadmium than from contaminated  sites.  Apparently, the bacterial popula-
tion had adapted to  the  heavy metal  contamination.   Khazael  and Mitra (1981)
found that cells of  E. coli  which were  adapted  to  growth in  0.34 ppm Cd in a
minimal   salts medium  produced  a Cd  binding high-molecular-weight cytoplasmic
component which  may  sequester Cd2+  in  the cells and  allow  normal  metabolic
function.  It is not  clear if this mode of adaptation to  Cd in the environment
is common to other microorganisms.

     Chaney  et al.  (1978) studied respiration rates of black  oak forest soil
and  litter  which had been  both "naturally"  and experimentally contaminated
with Cd  and  Zn.  After 23 days  incubation, soil   and litter microcosms treated
with 10  ppm  Cd and  no zinc had  significantly lower respiration rates than the
control.  The most severely  reduced  respiration  rate  occurred  when  10 ppm Cd
plus 1000 ppm Zn was  applied.   But  even this  highest  combined treatment rate
was not  significantly lower  than  the control.   Apparently the litter-soil
system  used in this  study was quite resilient to contamination  by  these
metals.

     The soil  microflora  may  have significant impact on Cd availability.   Work
by Kurek et  al.  (1982)  has   shown that  soil microbial  biomass  may contribute
significantly to the  soil Cd binding capacity.    Dead  bacterial  cells sorbed
more Cd  from liquid medium than  did live cells.

     Since cadmium exists in  nature only in the valence state of +2,  microbial
oxidation or reduction of this  element is unlikely.

Chromium
     Although  chromium  has  common  valence states of  +2, +3, and +6,  and
should be  amenable  to  oxidation  or  reduction   by  microbes,  no information
is  available  on the biochemical   transformation of  chromium   (Zajic  1969).
Hexavalent chromium  has  been shown  to  be toxic and mutagenic  to Salmonella
typhimurium, while  trivalent chromium was neither  toxic or  mutagenic  in
the same tests (Petrilli  and  De Flora 1977).   Ross et  al.  (1981) tested
the toxicity of  Cr+6  and Cr+3 to liquid  cultures  of  soil bacteria  and  con-
cluded that   Cr+6 was more toxic than  Cr"1"^  and that  gram  negative bacteria
were more sensitive  to  Cr+6  than  were gram  positive bacteria.    When  they
treated   a loam  and  fine  sandy  loam  soil  with  Cr+3 or Cr+6 under laboratory
conditions,  they observed decreased soil respiration (C02  evolution)  in  both
treatments.   Small  amounts  of extractable  Cr+6  were  observed  within 6  days
of treatment  with  100 ppm  Cr+3,  but  no  Cr+6  could  be extracted  from  this
treatment after  13 days  incubation.  Extractable levels of Cr+6  decreased  to
less than 5  ppm  after 13 days  incubation of  the soils  treated  with 100 ppm
Cr+6  but no increase in  soil respiration was  observed  in  any of  Cr+6  or
Cr+3 soils in up to  22 days  incubation.   Apparently, it should not be assumed
that Cr*3 is harmless to the  soil microflora.   Working with  laboratory  media
alone,  Babich et al.   (1982)  demonstrated  that Cr+6  was  significantly  more
toxic than  Cr+3 in  terms of  spore  germination,  growth, and sporulation
to six  species  of soil  fungi.   However,  at  100  ppm  (the lowest  treatment


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reported) of  either  Cr+3  or  Cr"1"^  the mycelial  growth  rate  of Penicilium
vermiculatum was not significantly different  from  the  control  culture.

Lead-
     Inorganic  lead  has  been shown  to  be  toxic  to  a broad  range of micro-
organisms including  cyanobacteria,  marine  algae,  fungi,  and  protozoa.  Lead
and its compounds have also  been  shown to affect microbial  activities  in  soil,
including inhibition of nitrogen  mineralization, stimulation of nitrification,
and the  synthesis of  soil  enzymes.   Species  diversity of microbes  in lead
contaminated soils  has also been found to be lower.   Babich  and  Stotzky
(1979) found  different sensitivities to lead  among  eight  species of fungi.
Rhizoctonia soloni ceased growth at 500 yg Pb/ml  of medium, while Aspergillus
niger was~not appreciably inhibited  by  1000  yg Pb/ml  of medium.    In  the same
study, Ph,  phosphate  and  carbonate  ions,  clay  minerals,  particulate  humic
acid,  and soluble organics  affected  the  toxicity  of  lead.  Low  pH of 5 or 6
increased the toxicity of  lead,  probably through  the increased  dominance of
Pb2+  ion,  while  higher pH  and the  other  abiotic  factors  tested  reduced
toxicity.  Apparently, hydroxylated,  sorbed,  or complexed  forms of Pb  are less
toxic to fungi,  and  probably to  other soil microorganisms.

Mercury--
     Microbiological  processes are  responsible for the oxidation, reduction,
methylation,  and  demethylation  of mercury.    Mercurial  pesticides,   phenyl-
mercury  acetate  (PMA),  ethyl mercuric  phosphate,  and  methyl mercuric  chloride
are all  biodegradable  (Kaufman  1974).   Metallic mercury is often  the  reduced
product  of the  decomposition  of  such compounds (Alexander 1977).  Monomethyl
or dimethyl mercury  may  also  be  formed  biologically in the soil   from  Hg2+ or
from organomercurials.   Landa (1978) monitored 203ng  ioss from   five  Montana
soils of varying  texture and  classification  which were ammended   with  Ippm Hg
as 203ngN03, and incubated for 7  weeks at room  temperature  at  1/3-bar  moisture
content.    Mercury loss ranged from  5  to 30 percent  with  the higher  initial
rates of loss  observed  in  soil  ammended  with glucose.   Losses  of  Hg from
autoclaved, but  not necessarily sterile, soil  of each  type  was much  lower.
After 2-24 days,  depending  on treatment  and  soil, very little if  any  Hg loss
was observed.    Inoculation  of  the  autoclaved soils  or  reamendment  of  the
treated  soil  after  38 days  did not  initiate  further Hg  loss.    Apparently,
the remaining  Hg was  stabilized  in  the  soil   and  unavailable  for microbial
processing.  Shariat et al.   (1979) screened  40 common  soil bacteria for  their
ability  to  tolerate and degrade methylmercury chloride.   Twenty-seven  (67.5
percent)  could  tolerate CHsHgCl  at  0.37 to  2.5  mg/1,  and 21 (52.5  percent)
could degrade  it.   The  disappearance  of CH3HgCl   from  the medium was  accom-
panied by a loss  of  total Hg, probably to volatilization  of Hg"  produced from
reduction  of CH3HgCl.  Mason  et al. (1979)  investigated  the  kinetics of
methylmercury chloride degradation by the bacteria Enterobacter  aerogenes  and
Serratia marcesens.    They  found  that  the   initial rate  depended on  C^HgCl
concentration  and pH, "and  that  the kinetic  pattern was  characteristic  of
enzymatic  reactions.   _._ aerogenes  exhibited  uniform kinetics   over the  pH
range tested, while S. marcescens had the highest  rate of  degradation  at  pH 8.
Calli'ster and  Winfrey (1983) found  that  both  aerobic  and anaerobic  hetero-
trophic  bacteria were  resistant to  14 ppm  Hg2+.    Mercury  methylation  was
highest  in anaerobicalIv incubated surface  sediments.   Nearly  all  (99  percent)
of the  Hg  added  as  203ng (N03)2 bound  to  the sediment  within  one hour,  but


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more than 7 percent of the  added  Hg  was  methylated  during  a 7-day incubation.
This suggests that bound  inorganic mercury was available  for methylation.   The
processes of mercury methylation  and demethylation  have  usually  been  ascribed
to  different bacteria  strains.    However,  Pan-Hou  et  al. (1980)  found that  a
strain of the mercury methylating, anaerobic bacterium Clostridium cochlearium
1-2  acquired  the ability to  decompose  methyl mercury  and other  organomercur-
ials.  Apparently this ability was coded  for on transferable genetic material,
probably  a  plasmid.   Silver  and  Kinscherf (1982)  have recently reviewed  the
genetics  and  biochemistry  of microbial  transformations of  mercury  and  its
compounds.   They point out that  mercury resistance is an  inducible  trait of
organisms possessing this  ability,  and   that  the genetic material coding  for
this ability is transposable.

Nickel--
     Nitrification,  carbon  mineralization,  and the  activities  of  acid  and
alkaline  phosphatase and  arylsulfatase  are all inhibited  in soil by nickel.
Babich and Stotzky (1982,  1983a,  1983b)  have studied the  toxicity of nickel to
microorganisms  in pure culture and in soil.  In pH  4.9 soil  without montmoril-
lonite clay minerals,  incipient  Ni toxicity  to fungi ranged from 50 ppm  for
Aspergillus clavatus to 750 ppm  for  Tri'choderma viride.   Only one species of
fungus  (Gliocladium  sp.)  showed any growth at 1000 ppm Ni.   Addition of
kaolinite or montmorillonite  clay reduced  the toxicity of  Ni  to fungi with
montmorillonite being most effective.  Increasing the  pH to  approximately  7.0
also reduced toxicity.  At 1000 ppm Ni,  adjusting the  soil pH to  approximately
7.0  with  CaC03 essential  ly  doubled  the fungal growth  rate.    Incipient  de-
creases in  survival  of unicellular  microbes  in the  same pH 4.9, Ni treated
soil  began  at  250  ppm  for Agrobacterium  radiobacter,  B acill us megateriurm
(both bacteria),  Cryptococcus  terreus  and Torulopsis  glabrata (both  yeasts).
Proteus  vulgaris,  Baci 11u~cereus"lboth  bacteria), Nocardia  rhodocnrous
Tanactinomycete),  Cryrtoco'ccus  terrus,  Rhodotorula rubra,and ToruTopsis
ajabrata  (all yeasts)  were viable after  7  days  exposureTcTlOOO  ppm Ni  in  the
pH  4.9 soil.   In a  pH 7.7  soil,  1000 ppm Ni  did  not  affect the viability of
the  six  bacteria and  yeasts  tested.   The pH 7.7 soil  also contained some
montmorillonite clay,   and significantly  higher amounts of magnesium than  the
pH  4.9 soil.   Apparently,  alkaline  pH,  type and amount of clay minerals,  and
other ions (e.g., Mg)  greatly  affect  the  microbial toxicity  of nickel.  Babich
and  Statzky  (I983b)  have also  reported  that  Mg2+  or Zn2+  cations,  and  S2~
and  P04~  am'ons  also  reduce Ni  toxicity.   However, K+,  Na+,   Ca2+,  Fe3+,
amino acids, tryptone,  casamino  acids,  yeast  extract,  and chelating agents
(citrate,  EDTA,  DPA, NTA)  did  not  reduce  Ni  toxicity.

Selenium--
     The  soil  microflora,  as  a  whole,  are  capable  of  several transforma-
tions of  selenium.    Since  organic  selenium  compounds do  not  accumulate  in
the  soil  in  areas where  organic  selenium compounds,   including  volatile di-
methylselenide,  are  common  in plant  tissue,  these  compounds must be mineral-
ized and  the selenium  released as selenite and/or  selenate.  Apparently, the
oxidation  of elemental  selenium in soil   is at  least partly mediated by micro-
organisms, but  the mechanisms  and organisms participating in the process have
yet to be discovered.  The  reduction of selenite  and  selenate by soil micro-
organisms is a relatively common  attribute,  but bacteria do not  seem  to
use  selenate or  selenite  as  metabolic  electron acceptors.    Selenium may  be


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methylated to dimethylselenide  by a variety of  soil  fungi and  bacteria,  and
rates of methylation  are  greatly accelerated  when a readily  available  carbon
source, such as glucose, is added to the soil  (Alexander 1977).

Silver
     The bacteriocidal property of silver is well  known  (Chambers et al.  1962,
Woodward 1963).   Sokol and Klein  (1975)  and  Klein and Molise  (1975)  studied
the effects of silver from cloud seeding agents on soil  and sediment microbial
activity.  In laboratory culture, silver ions  from AgN03 or ^rom saturated  Agl
exhibited  about  the  same  level of  toxicity  to  Arthrobacter sp.   Anaerobic
cellulose  degradation  was  inhibited  in muds  amended  with  100 ppm Agl,  and
apparently, organic  matter decomposition was  inhibited in soil  contaminated
with Agl from a cloud  seeding devise.   Silver  concentration  in  these contami-
nated forest soils reached  nearly  1500  ppm  (organic matter free basis).   From
this and  studies  in  a semiarid grassland soil, these  investigators concluded
that  the threshold  level   of  impact of  silver   to  soil   decomposer  activity
was  1-2  ppm Ag.    Approximately 11 percent of the bacteria  in  the grassland
soil which  was  not treated with Ag  could  reduce Ag+ ions to metalic  silver.
Experimental plots  treated with approximately 100 ppm  Ag  to  a depth of  2 cm
had significantly higher numbers (22 percent of total)  of Ag+  reducers.

Vanadium
     Ammonium vanadate  and vanadium pentoxide  may be components  of hazardous
waste  (40  CFR  261).   Vanadate  may be reduced by  microorganisms  under  appro-
priate conditions to  vanadium oxide.  Ferric  ion  produced  by  the oxidation of
Fe2+ by  the Thiobacilli has been  shown to oxidize V+3  to V+5.   Vanadium is
chelated  by EDTA  and  presumably  by humic  acids and  other  natural  ligands
(Zajic 1969).

Decomposition of Xenobiotic Organic Compounds

The Role of Microorganisms--
     Most of the  compounds that  can  render  a  waste hazardous  are organic,  and
many  of  these hazardous  organic  compounds  are   synthetic and   without  close
structural analogs in nature.  The molecular  structure of  some of these
compounds  was  purposefully designed  to resist  microbial  attack  and  hence
prolong the persistence of the  compound in  the environment.   However, many of
these  compounds  are  susceptible  to some kind of transformation  or complete
mineralization by microorganisms  in  the environment.   Where biodegradation is
possible,  augmentation of the soil microbiota with cultured  organisms  and/or
manipulation of  the  soil  environment  through chemical  or physical means to
optimize the desired activity may accelerate the  biotransformation or mineral-
ization  process.   Alexander (1981)  has  pointed out that few abiotic processes
completely mineralize  complex  organic compounds  in nature  and complete degra-
dation of  these  compounds depends on microbial  activity.   However, physical/
chemical  transformation processes  may  act  synergistically  with  biochemical
decomposition  in  the decomposition  of compounds  of  environmental  concern.
For  example,  simultaneous photo  and   microbial   decomposition   of 2,4,5-tri-
chloroanaline  in river  water  was  nearly  twice   as  fast  as  photodegradation
alone, and  more  than  10 times  as fast as microbial mineralization  in the dark
(H.-M. Hwang and  R. E. Hodson, personal communication,  May 1983, University of
Georgia, Athens).

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Genetic Engineering
     The resistance of many organic  chemicals  to  degradation  in the environ-
ment  has  prompted  a  search  for  techniques to  improve the  capabilities of
microorganisms in degrading these compounds.  The use of genetic manipulation
of microorganisms to enhance the  production  of  biological materials of commer-
cial  importance  has made  significant  advancements in  recent  years (Hopwood
1981),  and  many of the principles  used can  be and have  been employed to
improve the degradative  capabilities  of microorganisms.   Many degradative
capabilities  in  bacteria  are  encoded  on  extrachromosomal  elements  called
plasmids.   Under appropriate conditions,  plasmids can be transferred from one
organism to  another,  and once  inside the cell can  impart  the  plasmid coded
trait  to  the new host.   Using  plasmid  manipulation techniques  it  has  been
possible to  "engineer"  organisms  that have extended degradative capability,
i.e., organisms that can degrade more than  one  xenobiotic  substrate or that
can  completely  mineralize  highly recalcitrant  molecules such  as 2,4,5-tri-
chlorophenoxyacetic  acid  (2,4,5-T)   (Kamp  and  Chakrabarty  1979, Chakrabarty
1980,  Chatterjee et al. 1981,  Johnston and  Robinson  1982, Pierce  1982).
Continuing  efforts  to   genetically manipulate  microorganisms  to be  able to
degrade recalcitrant  hazardous  compounds  hold out great hope for  future
treatment  of contaminated soil  and other environments.

     Concerns have  been  expressed over the  ability of genetically engineered
microorganisms to survive and  function in  the complex  soil or aquatic environ-
ment (Stotsky and Krasovsky 1981).  Since the permutations of interactions of
factors in  the  environment  which  influence  microbial activity  and  growth in
the  soil  are essentially unlimited,  it  is  difficult to predict  the  fate of
organisms  with new  or  extra  genetic  material  (Stotsky  and Krasovsky 1981).
Unless the new genetic  information increases  an organism's ability to detoxify
its  environment, or increases  its ability to  use  a broader substrate range,
maintaining  the genetic material would seem energetically disadvantageous for
the  organism,  and  the  organism or its  new  genes  would  be  selected against.
However,  Liang et al.  (1982) have suggested  that mutant organisms that toler-
ate abiotic  stresses, resist starvation,  and can coexist with  antagonists may
persist in  the environment for  extended  periods.  Kilbane et al.  (1983)
observed that  a  genetically engineered  Pseudpmonas cepacia,  which  could use
2,4,5-T as its sole source  of  carbon, maintained  high populations in soil as
long  as appreciable amounts  of  2,4,5-T  were  present,  but decreased  to un-
measurable levels  when  2,4,5-T was exhausted from the  soil.

     There  is  some  indirect evidence that  plasmid born genes may  be trans-
ferred among bacteria  in the soil, and it has been suggested that some degra-
dative plasmids have evolved through  the  natural  combinations  of plasmid DNA
from different organisms (Pemberton et  al. 1979,  Chatterjee et al. 1981).  No
information   is available  on the  ability  of introduced  microbes  to transfer
genes  to  indigenous organisms  in natural   habitats  (Stotsky  and  Krasovsky
1981).

Effect of  Structure--
     Many  factors,  some of them only  poorly  understood,  determine the degrad-
ability of an organic compound.   Molecular  structure  and degree of substitu-
tion  may  be  important.    Apparently,  for  polychlorinated biphenyls  (PCBs)
recalcitrance is  related  to  the degree of chlorination and the position of the


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chlorine moieties on the ring structure of the molecule (Furukawa  1982).  The
number of fused  rings  in  polynuclear  aromatics  (PNAs)  is important in deter-
mining the  rate  of their  decomposition  (Sims  and Overcash  1983).   Paris et
al.  (1983)  found  an  inverse relationship  and  a high correlation  between
microbial transformation  rates  and van  der Waal's  radius  of  8  phenols and
suggest that this molecular property may be  useful  in predicting degradability
of  xenobiotics.    More basically,  the  biodegradability  of  complex  organic
molecules depends on the existence  or  inducibility  of enzymes  in the microbial
population which  are  capable  of catalyzing the  reactions  needed.   Alexander
(1981) has compiled lists  of type reactions  for transformation of chemicals of
environmental concern, but points  out  that the list is far from complete,, and
that more research is needed to  provide this  kind of information.

Cometabolism--
     Xenobiotic  organic  compounds  are  usually  transformed  or degraded  by
microorganisms  in  either  a metabolic sequence which provides  energy and
nutrients (i.e.,  C,  N, P,  etc.)  for  growth or  maintenance  of  the organism,
or  by a  biochemically mediated reaction  which   provides  neither  energy or
nutrients to  the cell.   The  first process  usually results  in  the complete
biqdegradation of  the organic molecule to  mineral products  (C02,  ^0,  NHL,
P0.~, etc.)  and  is called  mineralization.   The second process usually results
in  only  a minor  transformation of the  organic  molecule  and  is  called co-
metabolism or  cooxidation   (Alexander  1973,  1977,   1982).   Two or more sub-
strates are  required for cometabolism; one  is the nongrowth substrate which is
neither  essential  for,  nor sufficient to, support  replication  of  the micro-
organism (Hulbert and  Krawiec 1977, Perry  1979),  while  the other  compound(s)
does  support  growth.   The  nongrowth  substrate is  only  incompletely oxidized
(or  otherwise transformed)  by the   microorganism  involved, although   other
microorganisms sometimes can  utilize  by-products  of  the  cometabolic process
(de Klerk and van der Linden 1974,  Perry 1979).

     It  is generally recognized that cometabolism results when  a non-specific
enzyme attacks a recalcitrant  molecule resulting  in metabolism of the compound
(Horvath and Alexander 1970, de  Klerk  and van der Linden 1974).  This could be
called a  "metabolic mishap" since  the organism  supplying  the enzyme gains no
benefit  from the  metabolic  transformation.   The  enzyme  is made by the micro-
organism to metabolize  some other  organic  compound in  the environment which,
when  fully  metabolized, could  provide energy  to  the  microorganisms (Perry
1979, McKenna  1977).   Oxygenases  are often  involved  in cometabolism because
they can be  induced by, and can  attack, a  large set of substrates (Perry  1979,
McKenna 1977).

     Cometabolism may be a  prerequisite for the mineralization of many recal-
citrant  molecules  in  the  environment.    For  example,   de  Klerk and  van der
Linden  (1974)  found  the  oxidation of  cyclohexane  to  involve  two distinct
steps.   First, the conversion of cyclohexane to cyclohexanol by a  Pseudomonad
bacterium which  was  using  n-heptane  as  its  energy source.   Second, cyclo-
hexanol  was  readily  utilized by  a second  strain  of Pseudomonad.   Beam and
Perry  (1973,  1974) reported  the  same general  results  for  the oxidation of
unsubstituted cycloparaffinic  hydrocarbons.   Over  100 strains  of bacteria were
tested  and  none  could  use  the  hydrocarbons as their sole  carbon  and energy
source.  However, many strains could partially oxidize the hydrocarbons when  a


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suitable  energy source  was  present  (e.g.,  n-alkane).    The  cycloalkanones
resulting from  the partial  oxidation  were  readily  oxidized and  used  as  an
energy source by other  strains  of bacteria (Beam and Perry  1974).  Unsubsti-
tuted  cycloparaffinic  hydrocarbons are  readily  mineralized  in natural   soil
systems, presumably by a process  including cometabolism (Beam and  Perry  1973,
1974).

     Cometabolism  probably  occurs frequently  in  natural   soil  systems  since
numerous  genera of bacteria,  fungi,  and  actinomycetes  have  been  shown  to
participate  in  the  process  (Horvath  and  Alexander 1970,  Alexander 1977).
Compounds incompletely degraded by cometabolism  are diverse  and  include
saturated  hydrocarbons,  halogenated  hydrocarbons,   numerous  pesticides, and
single ringed polycyclic  aromatic hydrocarbons (Horvath  1972, Raymond et al.
1969,  Horvath   and  Alexander  1970,  Alexander  1977,  Merkel   and  Perry  1977,
McKenna  1977, Perry 1979,  Sims  and Overcash  1983).   Since cometabolism  is  a
generally occurring  process and has the  potential for transforming very
refractory compounds to  compounds which are more  easily  degraded, it may  be
important in the  biodegradation  of complex organics  in  hazardous waste  con-
taminated soils.   Treatment to  encourage  cometabolism  may  include  adding   a
more  easily  degraded  compound  which  is  a chemical   analog  to  the hazardous
compound that must  be  decomposed  in the soil.   Figures  3-44 and  3-45 illus-
trate the effect of several  different  growth substrates  on the rate  at  which
C02  was  released   from  malathion.   Other  growth  substrates,  including   glu-
cose, glycerol, and glycerophosphate,  did  not have  an  appreciable effect  on
the  rate of [^C]  carbon dioxide  evolved  from  malathion  (Merkel and  Perry
1977).  Table 3.46  shows the relative effects  of naphthalene  and  phenanthrene
as growth substrates for the cometabolism of four polynuclear aromatic hydro-
carbons  in  water  (McKenna 1977).   Sims and Overcash (1981)  showed  that the
rate  of  cometabolism  of  benz(a)pyrene  was significantly  increased  when the
soil was enriched  with  phenanthrene as  an  analog.

Degradation of  Organic  Pesticides--
     Seventy of the organic based  compounds  listed  by  the  U.S.  EPA  as  con-
stituents of hazardous waste have been or  are  used as   pesticides.    These
compounds are listed by broad classes of  compounds  in  Table 3.47.   Insecti-
cides, acaricides, rodenticides, and herbicides are  all  represented.  Concern
over  the environmental  fate and public  health effects of pesticides has
focused a great deal of research on the biodecomposition or  transformation  of
many  of  these   compounds,  and  much can be  learned   about  hazardous  organic
compound  degradation  from these  studies.    Here  we   will   concentrate on the
classes and specific pesticide compounds  included as  constituents  of hazardous
waste.

     Decomposition   of  the  chlorinated  hydrocarbon  pesticides  has been the
frequent  topic  of  research.    The litersture pertaining  to this topic has
been  reviewed by  Kaufman (1974),  and  Matsumura  and  Benezet  (1978).   Reduc-
tive  dechlorination  under anaerobic conditions  and   cometabolism  seem  to  be
central  mechanistic  principles  for  these compounds (Horowitz  et al.   1983,
Sulflita et al.  1983).   However,  greater metabolic diversity of  microorganisms
degrading these compounds is being discovered  (Stanlake and Finn  1982,  Edge-
hill  and  Finn  1983, Nielson  et  al. 1983), and  the  importance  of sequential
metabolism by microbial consortia  is being  recognized.  For example,  a strain


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                                50   IOO  ISO   200  250

                                INCUBATION  TIME (HRS )
Figure 3-44.   Evolution of ^C02 from Core Creek soil  suspensions amended with
              [l4C]malathion.   (0.1 yCi of [14C]malathion  added  to each flask
              at beginning  of the  experiment.    NO IND  = no  inducer  added;
              ^17:1 =  1-heptadecene;  C]j  = n-tridecane;  C]_3:i  = 1-tridecene.
              Control  was 1 g of soil/50 ml of  basal medium autoclaved for 50
              min on three  consecutive  days.)   (From Merkel  and  Perry 1977.)
              Used  by permission, see Copyright  Notice.
                                                 17 I
                                 iO   100  ISO   200  250


                                  INCUBATION TIME IMPS )
 Figure  3-45.   Evolution  14C02  from  tobacco  field  soil  suspensions.   Conditions
               same  as Figure  3-44  with CTJ   n-heptadecane also  added  (from
               Merkel  and  Perry  1977).   Used  by permission  see Copyright
               Notice.
                                       152

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       TABLE 3-46.  PERSISTENCE OF POLYNUCLEAR AROMATIC HYDROCARBONS IN
                      NATURAL WATERS (FROM McKENNA 1977)
                   Used by permission,  see Copyright Notice
  Non-Growth
   Substrate
   Growth
  Substrate
 Amount Non-Growth
Substrate Remaining
 After Four Weeks
Pyrerte
3,4-Benzpyrene
1,2-Benzanthracene
1,3,5,6-Dibenzanthracene
Naphthalene
Phenanthrene

Naphthalene
Phenanthrene

Naphthalene
Phenanthrene

Naphthalene
Phenanthrene
      36.7%
      47.2

      83.5
      38.3

      58.3
      33.8

      92.7
      32.9
of Hydrogenomonas  in  consortium  with the fungus  Fusarium can mineralize  DDM
(bis-(p-chlorophenyl)methane),  a metabolite of DDT  (Focht  1972).   Chlorinated
hydrocarbon pesticides tend to be persistent in soil, but  several  of  them  are
short lived.  Hexachlorocyclohexane  (Lindane) for  example  disappears from soil
quite rapidly  through a  combination of chemical  and biological  degradation
mechanisms.  The  persistence  of  chlorinated hydrocarbons and their metabolic
products  in  soil  may  be affected  by their incorporation  into  soil   organic
matter  (Bartha  1980,   Bollag  and Liu 1983).   Some  chlorinated  hydrocarbon
pesticides have been shown to be toxic to soil microbial  activity  (Chendrayan
and  Sethunathan  1980,  Subba-Rao  and Alexander 1980,  Tarn  and  Trevors 1981,
Trevors  1982).

     The microbial  degradation of organophosphate  pesticides has  been  reviewed
by Kaufman (1974), Matsunura  and  Benezet  (1978),  and Munnecke et  al.  (1982).
Organophosphate pesticides  exhibit  relatively low  persistence  in soil,   and
this property influences  their widespread use despite  their mammalian  toxicity
(Hsu and Bartha 1979).  Microbial  decomposition is the major degradative route
for organophosphorus insecticides (Miles et al . 1979).  Decomposition  usually
proceeds  through oxidative pathways, but  reductive mechanisms have been
reported  (i.e.,  parathion    aminoparathion)  (Matsumura  and  Benezet  1978).
Hsu  and  Bartha (1979) point  out that  microbial  metabolism  of  diazinon   and
parathion appears  to be cometabolic  at least in the first  step.  The  enriched
environment of the plant  rhicosphere  apparently stimulates microbial  activity
and accelerates microbial mineralization of organophosphate insecticides (Hsu
and  Bartha  1979,  Reddy  and  Sethunathan 1983).   The diffusion  of parathion
through  the soil is appreciably  restricted  by  microbial  activity  after a  lag
                                      153

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TABLE 3-47.  PESTICIDES INCLUDED AS CONSTITUENTS OF HAZARDOUS WASTE (40 CFR
                                     261)
Chlorinated Hydrocarbons
     Aldrin
     Chlordane
     Chlorbenzilate
     ODD
     DDE
     DDT
     1,2-Dichlorobenzene
     1,4-Dichlorobenzene
     1,2-Dichloroethane
     Dichloromethane
     1,2-Dich1oropropane
     1,3-Dichloropropene
     Dieldrin
     Endosulfan
     Endrin (and metabolites)
Heptachlor (oxidation product-
   Heptachorepoxide)
Hexachlorbenzene
Hexachlorocyclohexane (Lindane)
Hexachloroethane
Hexachlophene
Methoxychlor
Pentachloronitrobenzene (PCNB)
Pentachlorophenol (PCP)
1,2,4-Trichlorobenzene
1,1,1-Trichloroethane
Trichloroethylene
Trichlorophenol
Toxaphene
Organophosphates
     0,0-Diethyl S- 2-(ethylthiolethyl phosphorodithioate
        (Disulfoton)
     0,0-Diethyl 0-2-pyrazinyl  phosphorothioate (Zinophos)
     Methyl parathion
     Parathion
     Phosphorodithioric acid (Phorate)
     Phosphorothioric acid (Famphur)
     Tetraethylpyrophosphate (TEPP)

Thiocarbamates
     Dial late (Avadex)

Dithiocarbamates
     Ethylenebisdithiocarbamic  acid, salts and esters (Nabam,
        Maneb, Zineb)

Phenoxyalkanoates
     2,4-Dichlorophenoxyacetic  acid (2,4-D)
     2,4,5-Trichlorophenoxyacetic acid (2,4,5-T)
     2,4,5-Trichlorophenoxypropionic acid (Silvex)

Aldehydes
     Acrolein (Aqualin)
     Formaldehyde
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                            TABLE 3-47.  CONTINUED
Alkyl halides
     Bromomethane
     1.2-Dibromomethane
     Tetrachloromethane

Cyclic ketones
     Kepone
     Maleic hydrazide

Dinitrophenols

     2-sec-Butyl-4,6-Dinitrophenol (Dinoseb)
     2-Cyclohexyl-4,6-Dinitrophenol (DN-111)
     4,6-Dinitro-o-cresol (DNOC)
     2,4-Dinitrophenol

Miscellaneous
     Acrylonitrile (Acn'tet)
     Ally!  alcohol
     4-Aminopyridine
     Amitrole
     Aramite
     Bis (2-chloroethyl) ether
     Carbon Disulfide
     Creosote
     Cyclophosphamide (Endoxin)
     Decamox
     Dimethoate
     Dimethyl phthalate
     Diphenylamide
     Ethylene oxide
     Fluoroacetamide
     Napthalene
     l-Naphthyl-2-thiourea (Antu)
     Nicotine
     Pronamide (Kerb)
     Strychnine
     Warfarin
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period or  period  of  adaptation  of the microbial  population  (Gerstl  et  al.
1979).   Phorate  has  been  shown  to  be inhibitory to  nitrification  in  soil
for up to  4  weeks,  after which activity returned.   In the same  study,  soil
respiration  (03  consumption)   increased  when  phorate  was  added  (Tu  1980).
Forrest  et al.  (1981)  found that  soil  that  had  been adapted  to diazinon
through  several  annual  treatments degraded  diazinon   rapidly.    Successive
treatments of the  soil  with diazinon  further  increased degradative  ability.
Freezing  and  thawing the soil  did  not adversely affect  its degradation  abili-
ty.   A Flavobacterium isolated from  the  soil  hydrolysed both parathion  and
diazinon.

     Kaufman  (1974), Matsumura  and  Benezet  (1978),  and Munnecke et  al.
(1982) have  reviewed the  microbial  decomposition  of  carbamate  pesticides.
The only carbamate  pesticides  listed  as  hazardous waste constituents  are
members  of the  thiocarbamate  and  dithiocarbamate subgroups.  The thiocarba-
mate  dial late is an  herbicide which controls  growth by  interfering with
cell  division.   The half-life  of dial late  in soil  has  been  reported  in
one study  as 12 days (Banting 1967)  and  4 weeks  in  another (Anderson  and
Domsch 1976).   Mineralization of  l^C-labeled  diallate nas been observed
and a fungus (Tridioderma  harzianium)  isolated which can  use  diallate  as
a  carbon source.   Other fungi  could  transform  diallate cometabolical1y
(Anderson and Domsch 1976).

     The  salts and  esters of  ethylene bisdithrocarbamic acid, which  includes
the fungicides nabam, maneb, and  zineb are  the only dithiocarbamates  included
as  constituent compounds of hazardous waste  (40 CFR 261).  These  compounds
degrade  primarily by chemical  means,  although  limited  microbial  degradation
has been  observed.    One decomposition  product is  ethylenethiourea (ETU),  a
known  carcinogen.   Apparently, ETU degrades  rapidly with ethyleneurea  as  an
intermediate  to  other compounds including C02 (Kaufman 1974).

     Phenoxyalkonate  herbicide  degradation  by  microbes  has  been  reviewed
by  Kaufman  (1974)   Cripps  and Roberts  (1978),  and  Munnecke  et   al.  (1982).
Recent concern over the mutagenicity of these  compounds and  the dioxin
contamination of  2,4,5-T has  prompted a  renewed  interest  in  the  degrada-
tion  of  these compounds.   Many  strains of  bacteria  and fungi   can  degrade
these  herbicides.   Complete  mineralization  of 2,4-D  by  soil microorganisms
has been  demonstrated, but  2,4,5-T is more  resistant  to  degradation.   Until
recently,  cometabolism  has been  the  only degradative mechanism  described.
Recently, reductive dehalogenation of  2,4,5-T  to 2,4-D by microbial  activity
in  anaerobic environments has been  described  (Horowitz  et al. 1983,  Sulflita
et  al. 1983).  Kilbane et al. (1982)  have produced, through "plasmid assisted
molecular  breeding"   (genetic  engineering)   a  strain  of  Pseudomonas  cepacia
which  will grow on  2,4,5-T  as a sole carbon source.   This  organism  has been
used to detoxify 2,4,5-T in  contaminated soil (Kilbane et  al. 1983).

Degradation of Polychlorinated Biphenyls (PCBs)--
     The  fate  of PCBs  in   soil-pi ant  systems  has  been reviewed  recently by
Pal et al. (1980).    They conclude that all  isomers of mono- and di-chloro-
biphenyls are degraded by various  aerobic  soil  microbes,  but  that a few tri-
and tetrachlorinated PCBs are  more resistant.   Only a few  species with five or
six chlorines  are   known  to biodegrade.   Biodegradation  of the  more  highly

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chlorinated PCBs has not been studied.  Furukawa (1982)  has  also  reviewed the
microbial  degradation of  PCBs.   This review  points  out that the position of
chlorine atoms  on  the  PCB molecule  is  important  to  degradabil ity as well as
the  number  of  chlorines.    Transformations  of  highly  chlorinated  PCBS are
probably cometabolic,  but  the  mixed microbial  population  of  the  soil may
perform extensive  decomposition.   Apparently,  highly  chlorinated  PCBs are
quite photolabile,  and Furukawa (1982) suggests that  if  photolysis and micro-
bial degradation of PCBs were combined more efficient  and  rapid decomposition
of  PCBs might  be expected. Liu  (1982)  also  concluded from  fermentor studies
with a  PCB degrading  Pseudomonas  sp.  that the position  of chlorine  substitu-
tion on the biphenyl  molecule helps  determine  a PCB isomer's  biodegradability,
and that higher  chlorinated  PCB  formulations  was much slower.  A genetically
engineered  pseudomonad,  with the capability  to completely  degrade  mono- or
dichlorobenzoates,  and  an Acinetobacter  sp.  or Arthrobacter sp.  capable of
growing on 4-chlorobiphenyl,  in combined  culture  were  able  to  utilize more
than 98 percent of mono-  and dichlorobiphenyls, with  liberation of equivalent
amounts of  chloride ions (Furukawa and Chakabarty 1982).

Degradation of Aromatic  Hydrocarbons--
     Sims  and Overcash (1983) have recently reviewed  the microbial decomposi-
tion of polynuclear  aromatic  compounds  (PNAs)  in  the soil environment.  The
toxicity of  PNAs  to  microorganisms  is  related  to   their  water solubility.
Cometabolism  appears to  be the biotransformation process  for PNAs  with more
than three rings,  and acclimation of soils to PNAs enhances  their ability to
degrade these compounds.

Degradation of Phthalic  Acid Esters--
     A broad  spectrum of soil  bacteria and fungi  have been  shown to degrade
phthalic acid esters (PAEs).  Mixed  populations of microorganisms  degrade PAEs
more rapidly than pure cultures  (Overcash  et al.  1982).

Degradation of Substituted Benzenes--
     The microbial  decomposition of chlorophenols  and  phenol   in  soil has
been  studied by Baker  and Mayfield  (1980).   They  found  that phenol, ,
and  -chlorophenol,   2,4-  and  2,6-dichlorphenol, and  2,4,6-trichlorophenol
were  rapidly degraded  in  aerobically  incubated  soil,  but m-chlorophenol,
3,4-dichlorophenol, 2,4,5-trichlorophenol  and  pentachlorophenoF were degraded
very  slowly  under  aerobic conditions.    None  of  the  compounds  tested were
degraded in  anaerobic  soil.   Sulflita et al.  (1982)  have  demonstrated the
potential  for dehalogenation of  haloaromatic substances by  anaerobic  microbial
communities using halogenated  benzoates.

QUANTITATIVE  DESCRIPTION  OF
ORGANIC DECOMPOSITION

     Microorganisms are  highly effective  in  removing  certain hazardous
organic constituents from  soil  systems.   Principles of  biological degradation
of  organic  substances derived  from  the  study  of  decomposition  in aqueous
systems provide the starting point for predicting  attenuation  in soil systems.
These principles also provide the fundamentals  for  explaining the effects of
toxic constituents  and  solid surfaces on  quantitative decomposition in soil
systems.   Organic  chemical decomposition  in  soil  systems is a  very complex

                                      157

-------
process which depends upon organic substance properties, soil properties, and
environmental factors  (Hamaker  1972,  Goring et  al.  1975).   The addition of
exogenous toxic  organic  wastes  to  soil   systems  greatly  increases  the com-
plexity of  soil  metabolic processes.   This is  partly  because  organisms are
exposed to at least three different  types  of chemicals:   1) readily consumable
substrates,   2)   toxic  constituents  which may  inhibit  metabolic  processes,
and  3)  non-readily  consumable  organics  which  may not  be  toxic,  but which
do  not  serve as  sources of  carbon  and  energy for  cellular metabolism (co-
metabolites).  The effects of these  functional classes of organics on the rate
and  extent  of metabolism  of  each  class  and the  effects of  solid surfaces
within the soil  system is very complex and very difficult  to describe  quanti-
tatively.  Nevertheless,  studies  concerning  herbicide and insecticide degrada-
tion in soil systems have provided  a quantitative basis  for extrapolating from
aqueous system fundamentals to  soil systems which can  be  utilized  as  a tool
for describing the biodegradation of hazardous waste constituents.

     In addition  to biological decomposition, the degradation of  a chemical or
class of  chemicals in soil can  also be  influenced  by  chemical degradation,
volatilization,  photodecomposition,  and  plant  uptake  and metabolism.   The
latter process will not be addressed in  this manual.

     The  goal in  this  section  is  to  describe  models  for evaluating and
predicting  the  disappearance  of certain compounds  or  classes  of  compounds
in  soils  with time.   Mathematically,  the  rate of  decomposition represents
a sink term  in organic transport models which are needed to  predict potential
groundwater contamination with respect to magnitude and  type of  contamination
and the  time  factor for  contamination  (rate of transport).  Thus, a descrip-
tion of quantitative organic  chemical decomposition in soil  systems is  neces-
sary to determine potential contamination  of groundwater, and  to  determine the
chemicals or  classes of  chemicals that require management, through control of
mass transport, and treatment  for destruction.

     Useful degradation  rate models of  organics  in  soils have been described
by  Hamaker  (1966,  1972)  and Goring  et al. (1975), and Rao and Jessup  (1982).
Two  basic models which may be used to  model the  fate  of toxic organic  sub-
stances  in  soil  systems  were described  by  Hamaker (1972).   The "power rate
model" can be expressed as:

     dc/dt =  -KCN                                                       (3-42)

where,  C is  the concentration   remaining  in  soil  solution  at  time t, k is
a rate constant,  and N  is the  order of reaction.   The second model, the
"hyperbolic rate model" can be expressed as:

     dc/dt =  - KI C/K2 + C                                              (3-43)

where,  KI,  K are  constants.    The  constant  K   represents  the maximum  rate
of  degradation that is approached as the concentration  increases.

     The  "power  rate model"   is  applicable  to  chemical  reactions in  homoge-
nous  solutions  and  reaction  occurs  in  proportion  to  the  concentration  in
solution.   The "hyperbolic  rate  model," which is similar  to  Michaelis-Menten

                                      158

-------
enzyme kinetics, simulates a catalytic  process.   That  is, degradation  is cata-
lyzed by  either microorganisms,  adsorption,  or complex formation with soils.

     A first  order rate  model  can  be obtained  from  both models.   When  N =
1 in Equation 3-42, the rate law becomes:

     dc/dt = - KC   ............       (3-44)

Also, when  K2C,  Equation  3-43 reduces  to Equation 3-44  with K  = i/l<2.
The first order rate  model  is widely used in modeling degradation of organic
compounds in soil systems (Goring et al .  1975)  because  of its  simplicity.  The
first order  rate  model  when coupled  with a transport equation,  provides a
simple model with  an  analytical  solution  for transport of pollutants in soil
systems.    Analytical  solutions  are generally  preferred  over numerical  solu-
tions that  require computing facilities  and large  amounts  of computer time.
Also, the half-life of a  pollutant,  a concept associated with the first order
rate, is independent of the  initial  pollutant concentration.  The degradation
rate constant  in  Equation  3-44 actually  represents  a lumped  parameter  for
several  complicated processes  responsible  for  dissipation  of organics taking
place in soil.   Rao and  Jessup (1982)  recently pointed out that it is satis-
factory to assume a constant value for  "global" degradation rate coefficients.
However,  the  degradation rate  could  be  represented   as  a function  of  soil
temperature and  soil -water  potential, two very important parameters  in-
fluencing the rate of  degradation in soil  systems  (Walker 1976a, b).

     Effect of sorption on the rate and extent of biodegradation is difficult
to assess  for  the  wide  range  of organics  and  complex mixtures involved.
Hamaker  and Goring (1976)  developed  a model for decomposition  of pesticides to
explain  the low degradation  rates at  low  residual  concentrations observed in
experiments that  were monitored for relatively long periods.  The model
organic  constituent (pesticide)  is  assumed to  be divided  into  available  and
unavailable fractions.   The available fraction  is  considered to  be mobile,
labile,  and is  subject to degradation and movement.   The unavailable fraction
is  characterized as  immobile  and  non-labile  with  no degradation  allowed.
However,  a first  order transfer rate  is  allowed  to describe  movement to  and
from the unavailable fraction.  The  decomposition is also assumed to be first
order (Figure 3-46).   The fresh chemical   in soil is  assumed  to  be available
initially,  but  as  time proceeds, the  unavailable  fraction  increases.   Hence,
based on  this  model, it is expected  that desorption will be more difficult for
aged samples,  as observed  by Saha et al . (1969).

     The  "two  compartment" model  is  formulated as follows:

     dc/dt  =  -  (K + K!) Ci + K.iC2                                      (3-45)

     dc/dt  = KiCi - K.!C2                                               (3-46)
where Cj and  ^2 are  concentrations  in the available and unavailable fractions,
respectively;  K  is  the  first order  decomposition  rate constant;  and  KI and
K_i are first order  transfer rate constants between the two fractions (Figure
3-46).    Solution of the  two  equations and  an  estimation of  parameters are
presented by  Hamaker and Goring (1976).

                                     159

-------
                  av a i 1 ab 1 e
                                       K
                                    -^decompos it ion
                   1    *-l
                 unavailable
Figure 3-46.
               Schematic description of "two compartment"  model  (after  Hamaker
               and  Goring  1976).   Used  by permission, see  Copyright  Notice.
     The ratio (K]/K_i)  is  a measure  of  the equilibrium between  the  sorbed
(unavailable)  and desorbed  (available)  fractions.    It  has  an effect  in  the
overall  degradation rate (Figure  3-47).  The degradation  rate deviation
from first order  increases  as  the ratio K]/K_i increases, i.e.,  the rate  of
degradation decreases as  the residual concentration decreases  (Figure 3-47).

     The rate  law models discussed thus  far  do  not  consider the  effect  of
environmental factors on the  degradation  rate.   Three of  these factors
will be discussed,  including:    1)  initial  concentration of the  chemical,
2) temperature, and  3)  moisture content.   These factors have  been reviewed by
Hamaker (1972) and recently by  Hurle and Walker (1980).

Initial Concentration

     Hamaker (1972)  presented data  showing that the  50 percent disappearance
time (DT-50%)  increases   as  the  initial  concentration  increases,  i.e.,  the
persistence increases  as  the initial concentration increases.   Walker (1976a)
has also observed the  same  phenomenon.  The  reduced  rate is  explained  either
by the  limited active  sites available  (Hance and  McKone 1971),  or by a toxic
effect on microorganisms  or  enzyme inhibition (Hurle and Walker 1980).

     Sims and Overcash  (1983)  compiled  data from the  literature and conducted
experiments at North Carolina  State  University concerning polynuclear aromatic
hydrocarbon (PNAs) initial degradation rates  and  initial  concentrations
(Figure  3-48).    The data indicate an  increasing trend  of  initial rate  of
degradation as the initial  concentration increases.
to  2C"C  temperature,  using  Arrhenius  equation,  with
No  apparent  toxic effects  of  PNA  on  microbial
concentrations studied.

Temperature
                                                     The data were norma'ized
                                                     G  =  1.013 (Table 3-48).
                                                activity were  evident  at  the
     Generally, an  increase  in  temperature  increases  the rate of degradation
of organic compounds in soil.  This phenomenon  is attributed  to a decrease in
                                      160

-------
                100
                                          k (decomp.) = 0.0152

                                          (ti/2decomp- = 45-
                                           0\R= 0.51

                                                1/2>106
                                                           300     350
Figure 3-47.
Disappearance of  total  chemical  for  different  sizes  of  bound
residue  reservoir,  i.e.,  k^  (binding)/k_i (unbinding) =  R
(Hamaker and  Goring  1976).   Used by  permission,  see Copyright
Notice.
                                      161

-------
                          Reoroduced from
                          best available copy.
                X	
           o2
           o1 J  *
             3  -,
      CT
           0
            o ..
Ct
O
LU
O
U_
O
UJ
     cr:
        TO'2 J
     - 10'3 =
        10-5
               ACENAPHTHENE
               ACFNAPHTHYLENE
               ACRID1NE
               ANTHRACENE
               BENZ (B)ANTHRACENE
               BENZO (b)FLUORANTHENE
               BENZO (k)FLUORANTHENE
               BENZO (a)PYRENE
               CHRYSENE
                                    - DIBENZ (a.J)ACR1DINE
                                    - DIBENZ Ca.h)ANTHRACENE
                                    - D1BENZOFURAN
                                     D1BENZOTH10PHENE
                                    - FLUORENE
                                     FLUORANTHENE
                                    - NAPHTHALENE
                                     PHENANTHRENE
                                     PYRENE
            10"1     10     101      102     103     104     TO5
              INITIAL  CONCENTRATION  (ug/g-dry  wt.)
Figure 3-48.  Rates of transformation  of PNA compounds in  soil as a function
            of initial  soil concentration.
                                 162

-------
             TABLE 3-48.  KINETIC PARAMETERS  DESCRIBING  RATES  OF  DEGRADATION  OF  AROMATIC  COMPOUNDS
                                    IN SOIL SYSTEM  (SIMS AND OVERCASH 1983)
en
CO

PNA

Initial Con-
centration
(n9/g soil)

k
(dayl)
Rate of
transformation
(yg/g-day)

t1/2a
(dayl)

Reference

Pyrocatechol
Phenol
Phenol
Fluorene
Kluorene
Indole
Indole
Naphthol
Naphthalene
Naphthalene
Naphthalene
1,4-Naphthoquinone
Acenaphthene
Acenaphthene
Anthracene
Anthracene
Anthracene
Anthracene
Anthracene
Anthracene
Anthracene
Phenanthrene
Phenanthrene
Carbazole
Carbazole
Acridine
Acridine
Benz(a)anthracene
Benz(a)anthracene
Benz(a)anthracene
   500
   500
   500
     0.9
   500
   500
   500
   500
     7.0
     7.0
25,000
   500
   500
     5
     3.4
    13.7
    10.3
    11.4
    40.0
    36.4
25,000
     2.1
25,000
   500
     5
   500
     5
     0.12
     0.12
     3.5
3.47
0.693
0.315
0.018
0.347
0.693
0.315
0.770
5.78
0.005
0.173
0.578
0.173
2.81
0.21
0.004
0.005
0.006
0.005
0.005
0.198
0.027
0.277
0.067
0.231
0.075
0.281
0.04fa
0.0001
0.007
1,735
  364.
  157.
    0.
  173.
  364.
  157.
  385
   40.
    0.
4,331
  288.
   86.
   22.
    0.
    0.
    0,
    0.
    0.
    0.
4,950
    0.
6,930
   33
    1.
   37.
    1.
    0.
    0.
    0.
5
5
016
3
5
5

4
035

8
6
6
714
054
050
073
208
196

056
                                                             16
                                                             67
                                                             16
                                                             005
                                                             00001
                                                             024
0.2
1.0
2.2
39
2
1.0
2.2
0.9
0.12
125
4
1.2
4
0.3
3.3
175
143
108
138
129
3.5
26
2.5
10.5
3
9.2
3
15.2
6250
102
m
m
1
m
m
m
1
m
m
1
h
m
m
m
1
m
m
m
m
m
h
m
h
m
m
m
m
1
m
m
Medvedev & Davidov (1972)
Medvedev & Davidov (1972)
Medvedev & Davidov (1972)
Groenewegen & Stolp (1976)
Medvedev & Davidov (1972)
Medvedev & Davidov (1972)
Medvedev & Davidov (1972)
Medvedev & Davidov (1972)
Herbes & Schwall (1978)
Herbes & Schwall (1978)
Sisler & Zobell (1947)
Medvedev & Davidov (1972)
Medvedev & Davidov (1972)
Medvedev & Davidov (1972)
Gardner et al. (1979)
Gardner et al. (1979)
Gardner et al. (1979)
Gardner et al. (1979)
Gardner et al. (1979)
Gardner et al. (1979)
Sisler & Zobell (1947)
Groenewegen & Stolp (1976)
Sisler & Zobell (1947)
Medvedev & Davidov (1972)
Medvedev & Davidov (1972)
Medvedev & Davidov (1972)
Medvedev & Davidov (1972)
Herbes & Schwall (1978)
Herbes & Schwall (1978)
Groenewegen & Stolp (1976)

-------
TABLE 3-48.  (CONTINUED)
PNA
Benz( a) anthracene
Benz( a) anthracene
Benz(a)anthracene
Benz(a)anthracene
Benz(a)anthracene ,
Benz( a) anthracene
Benz( a) anthracene
F luoranthene
Fluoranthene
Fluoranthene
Fluoranthene
Fluoranthene
Fluoranthene
Fluoranthene
Pyrene
Pyrene
Pyrene
Chrysene
Chrysene
Chrysene
Benz(a)pyrene
Benz(a)pyrene
Benz(a)pyrene
Benz(a)pyrene
Benz(a)pyrene
Benz(a)pyrene
Benz(a)pyrene
Benz(a)pyrene
Benz(a)pyrene
Benz(a)pyrene
Initial Con-
centration
(yg/g soil)
20.8
25.8
17.2
22.1
42.6
72.8
25,000
3.9
18.8
23.0
16.5
20.9
44.5
72.8
3.1
500
5
4.4
500
5
0.048
0.01
3.4
9.5
12.3
7.6
18.5
17.0
32.6
1.0
(day-1)
0.003
0.005
0.008
0.006
0.003
0.004
0.173
0.016
0.004
0.007
0.005
0.006
0.004
0.005
0.020
0.067
0.231
0
0.067
0.126
0.014
0.001
0.012
0.002
0.005
0.003
0.023
0.002
0.004
0.347
Rate of
transformation
(yg/g-day)
0.062
0.134
0.060
0.130
0.118
0.257
4,331
0.061
0.072
0.152
0.080
0.125
0.176
0.379
0.061
33
1.16
0
33
0.63
0.007
0.00001
0.041
0.022
0.058
0.020
0.312
0.028
0.129
0.347
(day!)
231
133
199
118
252
196
4
44
182
105
143
109
175
133
35
10.5
3
-
10.5
5.5
50
694
57
294
147
264
30
420
175
2
i
m
m
m
m
m
m
h
m
m
m
m
m
m
m
m
m
m

m
m
1
1
m
m
m
m
m
m
m
h
Reference
Gardner et al. (1979)
Gardner et al . (1979)
Gardner et al. (1979)
Gardner et al . (1979)
Gardner et al. (1979)
Gardner et al . (1979)
Sisler & Zobell (1947)
Groenewegen & Stolp (1976)
Gardner et al. (1979)
Gardner et al. (1979)
Gardner et al. (1979)
Gardner et al. (1979)
Gardner et al. (1979)
Gardner et al. (1979)
Groenewegen & Stolp (1976)
Medvedev & Davidov (1972)
Medvedev & Davidov (1972)
Groenewegen & Stolp (1976)
Medvedev & Davidov (1972)
Medvedev & Davidov (1972)
Herbes & Schwall (1978)
Herbes 8< Schwall (1978)
Groenewegen & Stolp (1976)
Gardner et al . (1979)
Gardner et al . (1979)
Gardner et al. (1979)
Gardner et al . (1979)
Gardner et al . (1979)
Gardner et al. (1979)
Shabad et al. (1971)

-------
                                      TABLE 3-48.   (CONTINUED)

Initial Con-
PNA centration
(yg/g soil)
Benz(a)pyrene
Benz(a)pyrene
Benz(a)pyrene
Benz(a)pyrene
Benz(a)pyrene
Benz(a)pyrene
Benz(a)pyrene
Benz(a)pyrene
Benz(a)pyrene
Benz(a)pyrene
Benz(a)pyrene
Benz(a)pyrene
Di benz( a, h) anthracene
Dibenz( a, h) anthracene
0.515
0.00135
0.0094
0.545
28.5
29.2
9,100
19.5
19.5
19.5
130.6
130.6
9,700
25,000
(day-1)
0.347
0.139
0.002
0.011
0.019
0
0.018
0.099
0.139
0.231
0.173
0.116
0.033
0.039
Rate of
transformation
(yg/g-day)
0.179
0.0002
0.00002
0.006
0.533
0
161.7
1.93
2.70
4.50
22.63
15.08
320.1
962.5
<&
2
5
406
66
37
-
39
7
5
3
4
6
21
18
s)
h
h
1
1
1

h
h
h
h
h
h
h
h
Reference
Shabad et al. (1971)
Shabad et al . (1971)
Shabad et al . (1971)
Shabad et al. (1971)
Shabad et al . (1971)
Shabad et al . (1971)
Lijinsky & Quastel (1956)
Poglazova et al. (1967b)
Poglazova et al . (1967b)
Poglazova et al. (1967b)
Poglazova et al . (1967b)
Poglazova et al. (1967b)
Lijinsky & Quastel (1956)
Sisler & Zobell (1947)
   = low temperature range  (<  15"C), m = medium temperature range  (15-25"C),  and h = high tempera-
ture range (> 25C).

-------
adsorption with increasing  temperature which makes more organics available,  or
to  an  increase in biological activity,  or  both.   The  second factor has  an
optimum temperature beyond  which biological activity decreases.

     The effect of temperature can be described  quantitatively by  the change
in  the  degradation  constant which  can be determined  using  the  Arrhenius
equation:

     K = A0e-(Ea/T)                                                   (3-47)

where A0 is a constant, R is the gas constant,  T is the  absolute  temperature,
and Ea  is  the  activation energy.   Equation 3-47  implies that  the rate law  is
known.   Usually,  the  rate  law  is  assumed  to be  first  order (e.g., Walker
1978).  The half-lives  at different temperatures can be estimated  by:

     log[t1/2(T1)] -  log[t1/2(T2)] = Ea/4.575 (1/Ti - 1/T2)             (3-48)

where  ti/2(T]J and  tj/2(T2) are the  half-lives  at  absolute temperatures
TI and T2.

     Temperature effect on  degradation  rate is important in terms  of assess-
ment of the seasonal  and geographical variation of  degradation  rates.  Knowl-
edge of  temperature  effects  allows  an  estimation of  assimilative  capacities
for organic wastes in soil  systems for different regions  of  the United States.
The effect  of  controlling  soil  temperature on  the  rate  of  degradation  of
organics  can  also be  quantified and  evaluated.   Overcash  and  Pal  (1979)
quantified the seasonal and geographical  variation  of  oil waste decomposition
(Figure 3-49).  The  annual  rate of degradation is  higher in high temperature
regions than  in  low temperature regions.   Field measurements also show in-
creased  disappearance  rates  with  seasonal  high   temperatures  (Walker   1970,
Schweizer 1976).


Moisture Content


     Hamaker  (1972) presented  data for several  pesticides  indicating  an
increase  in the degradation rate with increasing soil  moisture content.
It was  observed that the degradation  rate increased  as the moisture content
increased up  to  field  capacity  (Walker,  1976  a,b,c;  1978).    Hamaker (1972)
suggested  the  following empirical  equation  to  quantitatively describe the
rate dependence on moisture content  for  organic constituents in soil systems:

     rate = r  + KWn                                                   (3-49)

where  W  is  the moisture content less than saturation, n  is  a constant  less
than one, K is a constant,  and r is the rate of degradation when  N  = 0.   Note
that when using Equation 3-49, it is assumed all  other  factors  are constant.

     Harris et  al.  (1969)  conducted  field  measurements   of  persistence  of
atrazine  and  chlorfenanc  at 12 locations.   For  both  chemicals  there was
more persistence  in  cooler  northern  and drier  western  states than  in the
semi-tropical  southern  states.

                                     166

-------
               0.6
                                                            ; 5

                                                            0 7

                                                            3 3

                                                            t i
Figure 3-49.
Effect of climatic conditions at major refinery locations on the
annual pattern  of oil  decomposition  (Overcash  and  Pal  1979).
Used by permission, see Copyright Notice.
     The quantitative  approach  to  determining  organic  constituent  degrada-
tion is  utilized  in  Volume I of the  manual.   The models presented  provide  a
rational framework for determining relative degradation  rates  of constituents
in a soil system as a function of temperature  and soil moisture.  When models
for degradation are combined  with simple transport models,  the  dynamic profile
in  a  soil  system  can be determined   and  used  to  identify those constituents
that require treatment  first.    Thus  a  prioritization of treatment  steps  and
processes can  be  developed based on  the  fate  of contaminants,  specifically
with respect to the potential  danger  to  public  health.


CHEMICAL REACTIONS IN THE SOIL  MATRIX


Introduction

     For a  site characterized  by large  quantities   of  hazardous waste  con-
taminated soils, consideration of in  situ  treatment  requires certain informa-
tion  related  specifically to  chemical   reactions in  the  soil-waste  matrix.
These  chemical  reactions can  be classified  into two functional groups  for
simplicity:  1) chemical   reactions involving  the soil medium,  and 2)  chemical
reactions involving chemicals  in the  soil  or soil solution. The latter group
of reactions may  occur   among  chemicals already  present at  the  site,  or  may
occur as a  result  of addition of a treatment  reagent  to the soil-waste matrix.
For in situ treatment it  is  anticipated  that all  immediate chemical  reactions
that  affect  public health  (explosion,   heat generation, flammability,  etc.)
will have occurred prior to site assessment for treatment.   Therefore chemical
reactions as a result of addition of  treatment  agent  will be  emphasized.
                                      167

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     This section  is  concerned with  the first  group of  chemical  reactions
identified above,  i.e.,  chemical  reactions  involving  the  soil medium.   The
effects of gross chemical structure of  inorganic  and  organic  chemicals added
to soil  systems are  considered,  including  acids, bases,  salts, nonionic
organics, surfactants,  and aqueous-solvent mixtures.  Effects on soil include:
1) dissolution,  2)  permeability 3)  sorption,  4) polymerization, and 5)  micro-
bial  activity.   These  effects  on soil  relate  specifically to soil treatment
process, i e., immobilization and degradation/transformation.

     Reactions among chemicals  in  the  soil  or soil  solution  are considered
with  respect  to health  hazard  (heat  generation,  fire,  explosion, formation
of toxic  fumes,  formation  of flammable  gases,  solubilization  of substances,
and  volatilization  of toxic  substances)  in Volume I for  specific  waste
constituent-treatment  agent  combinations.

Effects of Waste Type  on  Soil Properties

Acidic  Wastes--
     Table  3-49 summarizes several   industrial  categories  that generate
acidic   waste  constituents.   Organic  acids  in  soil  systems  are  very  likely
to undergo  biodecomposition  with  evolution  of C02,  stimulation  of microbial
populations,  and  consumption  of 02  resources.   If there  are carbonates in
the  system,  such as  in  calcareous  and  sodic  soils,  C02  may  evolve  through
reactions of  the  acid  with carbonate  and  bicarbonate  species  (Pal   et  al.
1977).    Under acidic conditions in  soils,  soubilities  of complexed  cations
such  as  Cu  and   Zn  increase,  and  Fe,  Mn, and  Cu  are  easily  reduced  to more
soluble forms.   Acidic  wastes may  also be  used as  treatment process  for
saline-sodic soils.

     The decrease  in  soil  pH due to  the  presence of hazardous acidic wastes
will   also change  the microorganism  distribution  within  the  soil  systems.
Under acidic conditions (pH  < 7) fungi predominate and  thrive in soil systems.
Biochemical  reactions  resulting  from  fungal  metabolism  of certain hazardous
chemicals may make soil  pH  an  important determinant,  not only of the type of
microorganism, but  also of the  metabolic pathway of degradation.

     Hydrocarbon-utilizing   organisms  possess   a  class  of  enzymes, known as
oxygenases,  which  incorporates  atmospheric oxygen into the inert  ring-struc-
ture as  the  initial  step in aromatic  hydrocarbon transformation and degrada-
tion.    The  substrate specificities  of bacterial  hydroxylation  mechanisms,
however, may differ from those of microsomal  enzyme systems present in fungal
tissues.   Fungal  systems  may  transform aromatic  hydrocarbons  by means of
monooxygenases into arene oxides, the  mutagenic form of PNAs (Cerniglia et al.
1979),   while  bacterial  systems carry  out the dioxygenation  of  the aromatic
nucleus  to  form  a  cis-glycol as the  first stable  intermediate, not the arene
oxide.

     These differences in the mechanism of aromatic hydrocarbon metabolism by
microogranisms  have   important  implications  for   engineering  techniques  for
controlling  and  possibly detoxifying  PNAs   in hazardous  waste  contaminated
soils.   Because  of the major differences with respect to  microbial oxidation
of aromatic  hydrocarbons between  bacteria  and  fungi,  it may be  especially

                                      168

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    TABLE 3-49.   INDUSTRIAL CATEGORIES  GENERATING ACIDIC WASTE CONSTITUENTS
                               (PAL  ET  AL.  1977)
                    Used by permission,  see Copyright  Notice
        Organic
          Inorganic
Winery Still age (3.5-5)
Paper and Pulp (4-6)
Organic Acid Manufacture (3-6)
Leather Processing (5-6)
Mineral Acid Manufacturing (3-4)
Dredge Mines (2-4)
Coal Processing (3-5)
Steel Cleaning (3-5)
Metal Plating (2-4)
Petrochemical Manufacturing (4-6)
important in soil  systems to  encourage  bacterial  growth and competition vis-
a-vis fungi.   Since  soil  pH has a  significant  effect  on the soil bacterial/
fungal  proportions,  pH may  be an  important  engineering tool  to  direct the
pathway of PNA degradation.

     Dissolution of clay minerals  in  the presence of  organic acids  has also
been  observed.  Those elements  comprising  the  framework cations  of clay
minerals, i.e.,  silicon, aluminum,  magnesium,  and  iron, greatly increased in
solutions phases  containing  organic acids  (Huang and  Keller 1971).   The
organic  acids  studied  included aspartic,  citric,  salicyclic,  taratric, and
tannic.   The most  rapid rate of dissolution occurs during the first 24  hours
of exposure of clay minerals  to organic  acids.   After 45 days of exposure, the
solution concentration  reaches a constant value.

     The  ability of organic  acids  to solubilize soil  minerals  has also been
observed  with  humic  and  fulvic acid  fractions.   Fulvic  acids  (FA)  and low-
molecular weight humic  acids  (HA) can  attack and degrade soil minerals to form
water-soluble  and  water-insoluble  metal  complexes,  depending  on how  much
metal per unit  weight  of HA  or FA  is  dissoved.   The ability of these organic
acid  fractions  to dissolve clay minerals is  believed  to be due to  their
ability to complex di- and trivalent  metal  ions.   Fulvic acid can dissolve a
proportion of the dominant cation in  the  clay,  forming a soluble complex and
replacing the removed cation with H+.   If  this process continues the FA will
degrade the clay structure (Schnitzer  and Kodama 1977).

     Table 3-50  presents  results summarizing  the  increase  in  solubility of
framework cations  of  clay minerals,  including  kaolinite,  illite,  and  mont-
morillonite in the  presence  of the organic acids listed previously.  Aluminum
dissolution from clay minerals  reached 60 ppm with  illite.  This concentration
is very high compared  to less  than  1  ppm solubility typical in aqueous solu-
tions.   Iron disolution was  observed  to  be  similar to aluminum in ratios and
concentrations.    In  strongly complexing  acids,   silica  solubility  rose  by
a factor  of  2 to  6  for the  kaolinites,  and  by  larger factors for  the 2:1

                                      169

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TABLE 3-50.   EFFECT  OF  ORGANIC  ACIDS  ON CLAY  SOLUBILITY  (HUANG AND KELLER 1971
      Element                Increase  in  solubility  (factor) over water
                           KaloniteIlliteMontmorillonite
Si 2-6
AT 10-50
Fe 10-50
15-30
10-100
10-100
12-25
10-50
10-50
layer clays.   Aspartic  acid was especially  active  in dissolving calcium  and
magnesium.   Clay mineral  framework  cation concentrations  are much lower  in  the
presence of water.

     Implications of these  observations  include:  1)  susceptibility of weather-
ing of  silicate  minerals in water  is not  followed  in reactions with organic
acids;  2)  dissolution  of clay  minerals  by organic  acid constitutents of
hazardous wastes may directly  impact  mass  transport and permeability aspects
of the  soil-waste  matrix;  3) toxic metal  ions  at  hazardous  wastes sites  may
also become mobile  through  chelation  with  natural  and exogenous organic  acid
fractions.

Basic Wastes--
     Basic  waste  addition  to acidic  soil  has been  reported  to increase  the
pH of  the  surface layer (4" -18")  but  not  the  subsoil  (Brown  1975).    Basic
wastes  would  be  expected to react  with  acidic  groups of  the  soil  system to
neutralize  the  buffer  capacity  of the  soil,  and  increase  the exchangeable
sodium  percentage  (ESP),  percent base saturation,  and  soil  pH.  Basic  waste
added to soil may result in  physical damage  to the  soil  system  with resultant
low permeability, decreased hydraulic  conductivity,  and  high runoff potential.
However, organic bases  added to soil  systems  may  increase soil buffer capacity
and exchange  capacity  as  the  bases  are degraded.   Generally  an increase in
soil  pH is  associated  with an  increase  in cation  exchange  capacity,  which
increases the buffering  action  of a soil  (Pal et  al.  1977).

Salts--
     Salt  affected  soils may be  classified  based  on  chemical  conditions
of the soil-waste system identified in Table  3-51.

     Soils   contaminated  by salty  wastes  become   friable,  flocculated,  and
permeable with a high osmotic concentration of the  soil  solution.   With  sodium
as the  dominant  ion,  and the SAR  of  the waste  above 30, sodium dominates on
the exchange  sites.  Subsequent  leaching of  salts by precipitation results in
dispersed,   deflocculated,  and   impermeable  soils.  In the  absence  of  salts,

                                      170

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              TABLE  3-51.  CLASSIFICATION OF SALT-AFFECTED SOILS
Soil Group
Sal ine
Saline-sodic
Sodic
EC of saturation
extract
(mmhos/cm at 25" C)
>4
>4
<4
ESP
(X)
<15
XL 5
XL 5
pH
<8.5
=8.5
>8.5
sodium soils become extremely dispersed  and  impermeable  to  water.   The effect
of sodium on hydraulic conductivity is indicated in Figure 3-50.

     In regions of  base  unsaturated  soils  (Southeastern U. S.),  addition  of
salt wastes may improve base saturation,  decrease exchange  acidity,  and
increase nutrient supply  (Pal  et  al.  1977).  Sodic  soils,  however,  can  only
be treated  in  place by  chemical  treatment with  calcium salts (gypsum)  and
leaching of excessive sodium  with  solutions low in  sodium  and  high  in  other
salts (Ca and Mg).   Critical  SAR values for  soil  are listed in Table 3-52.

     Overcash  and  Pal  (1979)  point  out that  treatment of a soil  that has been
salt-damaged is a difficult and slow process.   If the damage is restricted to
the shallow soil  surface  layer, restoration  is easier since amendments can be
mechanically incorporated  into the  soil.   Restoration may be  accomplished
within months.    However,  if structure  deterioration has  progressed to  the
upper B horizon, calcium  salts  must be leached into the B horizon zone through
the severely restrictive  deflocculated zone.  This process  for  soil  restora-
tion may require  several  years.

Solvents--
     Very  little information has been  generated concerning  the behavior
and effects of the solvent class of organic  constituents on terrestrial
systems  and  on transport  through  terrestrial  systems.    However,  assessment
of hazardous  waste sites  has identified numerous organic solvents  present
in soil as well as  groundwater  samples.

     Volatile  solvents  are  known to  exert  an  initial soil  sterilization
effect on soil  systems  as the critical dose  level is achieved.   Soil recovery
is indicated by an increase in soil  microbial  activity and degradation of the
solvent.    Solvents  of  low volatility produce very little  soil  sterilization
when applied  in  moderate  to  high  levels.   Table 3-53 lists   solvents,  the
critical  soil   levels for soil  microbial populations,  and  the time period for
recovery at the critical  dose.

     Solvents also  have an  effect on the physical properties of  soil.  Several
studies have indicated that organic solvents,  in general, will  react with clay

                                      171

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                                        20
3O
       4O
                               EXCHANGEABLE- SODIUM
                                    -PERCENTAGE
Figure 3-50.   Influence  of exchangeable  sodium percentage  on  the  hydraulic
              conductivity  of  a clay loam (Overcash  and  Pal 1979).  Used by
              permission, see Copyright Notice.
      TABLE  3-52.   CRITICAL SAR VALUES FOR SOIL (OVERCASH AND PAL  1979)
                   Used by permission, see Copyright Notice
                       Soil
            SAR
              Swelling clay (bentonite)
              Nonswelling clay
              Pure  sand
              Loam  or finer textures
                 (>10% clay)
             8-10
            20
           750
             5-15
     TABLE 3-53.   RESPONSE OF SOIL MICROBIAL POPULATIONS TO APPLICATION OF
                       SOLVENTS (OVERCASH AND PAL 1979)
                   Used  by permission, see Copyright Notice
Solvent
Cyclohexane
Hexane
Heptane
Pentane
Formaldehyde
Chloroform
Ether
Acetone
Pyridine
Critical soil
level (ppm)
840
430
10,000
7,200
150-300
590
7,400
58,000
7,900
Time period for recovery
at critical dose
(days)
within 37 days
within 19 days
within 24-63 days
within 30-53 days
within 22 days
within 12 days
within 14 days
within 12 days
within 16-30 days
                                     172

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minerals in soil systems resulting in an increase in permeability of the clay
fraction (Buchanan 1964, White  1976,  Anderson  1981,  Anderson and Brown 1981,
Schram 1981, Anderson et al.  1982,  Brown  and Anderson 1983, and Brown et al.
1983).  A change in permeability is related  to  a  change  in the relative volume
that a given clay  occupies  as a function  of the adsorbing liquid.  A solvent
property that  can be  used  to  describe the magnitude  of the  result  of the
clay-solvent interaction, or  change   in permeability,  is  the dielectric con-
stant of a liquid.  A clay surface in contact  with a  high dielectric constant
liquid undergoes  swelling.   Conversely, a  low dielectric  constant  liquid  in
contact with a clay surface  will  cause very  little swelling.   In  the situation
where a soil  system containing a high  dielectric  constuant fluid  (e.g., water)
receives a concentrated waste  containing  a low dielectric  constant liquid
(solvent),  an increase in soil  permeability  may be anticipated as the relative
clay-liquid volume decreases.

     Table 3-54 contains dielectric constants  for several solvents identified
at hazardous waste sites.  It  is also  apparent  that organic  solvents generally
become less water soluble with decreasing dielectric constant.

     The effect of specific solvents on  soil  permeability is summarized
in  Table 3-55  (Anderson and Brown  1981).   General classes   of organics,
including  acidic,  basic, neutral polar,  and  neutral  nonpolar   are included.
From Table 3-55 it is  evident  that most  solvent organics  increase permeability
of clay minerals in soil  systems.

     While a  decrease  in water  solubility  is generally associated  with  an
increase in  sorption  for the  solvents  listed, this is  not  true for several
solvents,  including carbon  tetrachloride, ethylene  dibromide, and trichloro-
ethylene (Rogers  and McFarlane   1981).    These  chlorinated  hydrocarbons had
relatively low  adsorption  in  batch  isotherm tests  to  several   surfaces,  in-
cluding  two  silty clay  loam  soils,   aluminum-saturated  montmorillonite,  and
calcium-saturated  montmorillonite.    Experimental  results  are  indicated   in
Table  3-56.   For  these chemicals the  K values indicate  that  only minimal
sorption would occur in  soil or  clay.  The sorption of  chemials did not exceed
6 percent,  except for  10 percent sorption of TCE  by Al-mortmorillonite.  It  is
important  to  point out  that  the elevated  volatility of these  solvents may
result  in  atmospheric  mass  transfer  as the  primary  pathway  in the  soil-
atmospheric system.

Surfactants--
     Surfactants are  organic  molecules  widely used  in  industry for cleaning
purposes.  Cationic surfactants  are  usually quaternary ammonium salts, while
nonionic surfactants  are characterized by  polymers  of  oxyethylene  (Cj^O)
with both  polymer  ends  attached  to  alcohol   and are nondissociated in water.
Anionic surfactants comprise  the  largest  class of detergents (80-85 percent)
and  consist  of  a sodium cation  and the  active organic  anionic surfactant
(Overcash  and  Pal  1979).   The anion  part is usually  a sulfate   or sulfonate.

     Application of surfactants to the soil  will affect physical and biologi-
cal properties.   For  a  total  soil concentration of approximately 100 ppm,  no
substantial  adverse microbial  response has  been noted.   A  large  amount  of
information  exists concerning  field  movement  of  surfactants  to  subsurface

                                      173

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TABLE 3-54.   DIELECTRIC CONSTANTS,  DENSITIES AND WATER SOLUBILITIES OF VARIOUS
 HALOGENATED AND NONHALOGENATED SOLVENTS (ANDERSON ET AL.  1983,  MELLAN 1977)
Name
Water
Methanol
Ethanol
Benzyl Chloride
Acetone
1-Propanol
1-Butanol
1-Pentanol
Pyr id i ne
Phenol
Dichloromethane
1-Bromopropane
1-Chloropropane
1,1,1-Trichl oroethane
Aniline
Chloroform
Bromoform
1, 1,2-Trichloroethyl ene
Toluene
Benzene
Carbon tetrachloride
Cyclohexane
Hexane
Dielectric
Constant
78.5
32.7
24.6
23.0
20.7
20.3
17.5
13.5
12.4
9.8
8.9
8.1
7.7
7.5
6.9
4.8
4.4
3.4
2.4
2.3
2.2
2.0
1.9
Density
(g cm-3)
1.00
0.79
0.79
1.10
0.79
0.80
0.81
0.81
0.97
1.05
1.31
1.34
0.89
1.34
1.02
1.48
2.89
1.48
0.87
0.88
1.60
0.78
0.65
Water Solubility
(a 25C
_
Miscible
Miscible
Moderately Miscible
Mi scible
Miscible
Miscible
Miscible
Miscible
Miscible
1.32%
NA
NA
Slightly Soluble
Soluble
0.82%
0.10%
0.10%
Slightly Soluble
Slightly Soluble
0.08%
45 ppm
NA
NA - not available.
   TABLE 3-55.   EFFECT OF ORGANIC SOLVENT IN CLAY PERMEABILITY (ANDERSON AND
                                  BROWN 1981)
Chemical
Class
Acid
Base
Neutral
Polar

Neutral
Nonpolar

Solvent
Acetic acid
Aniline
Acetone
Ethyl ene Glycol
Xylene
Heptane
Effect on
Permeabil ity
decrease
increase
increase
increase
increase
increase
Comment
dissolution of clay
100 fold for Lufkin3
10 fold for H.B.a
1000 fold for Lufkin
50 fold for H.B.
100 fold for Lufkin
4 fold for H. B.
1000 fold for Lufkin
100 fold for H.B.
similar to Xylene
aSmectite clay.
                                      174

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  TABLE 3-56.   SORPTION OF HALOGENATED OR6ANICS ON SOIL AND CLAY (ROGERS AND
                                MCFARLANE 1981)
Adsorbent
Clay   Organic
(%)    carbon
Freundlich constants
        EDBb

Silty clay
loam
Silty clay
loam
Al -saturated
montmorillonite
Ca-saturated

31
34
100
100
(*)
2.6
1.8
0
0
K
0.62
1.18
1.75
NSd
1/n
1.08
1.04
0.88
NS
K
1.31
1.49
0.47
0.05
1/n
0.93
0.92
1.04
1.03
K
3.89
1.57
6.96
NS
1/n
0.82
0.93
0.92
NS
 montmorillonite
aCT = carbon tetrachloride.
bEDB = ethylene dibromide.
CTCE = trichloroethylene.
dNS = Not sufficiently sorbed to determine constants.
waters (Sebastiani et  al.  1971).   These situations involve  very concentrated
solutions in land fill  operations.   Overcash and  Pal  (1979)  point out that the
adsorption process for surfactants  in most  soils cannot  be  considered instan-
taneous,  but rather occurs at a finite  rate.   Therefore  saturated flow condi-
tions should  be  avoided.   Table  3-57  lists  results of  the adsorption  of  a
cationic  and  a  nonionic  surfactant by  montmorillonite  clay as  a function  of
surfactant concentration.

     While surfactants may be toxic to soil microoganisms  at high concentra-
tions (> 10,000  ppm),  the  most  severe effects of  surfactants in soil systems
would most likely  involve  mass  transport  of toxic and hazardous constituents
through soil systems.  Very little  information is  available concerning actual
mass transport of toxic substances  in  soil  systems  due to surfactant addition.

Desorption

     A very  important  area where  initial  soil-waste interactions  may affect
subsequent constitutent mobility is desorption.  Desorption  of  chemicals  from
soil  systems  may result  from precipitation events following a contamination
event, or may occur as a result of  addition of  amendments for  land treatment.
The chemical  matrix  of the waste appears  to  have  an important  effect  on the
subsequent behavior of  waste  constituents  in soil  systems.

                                      175

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    TABLE  3-57.   ADSORPTION OF SURFACTANTS ON MONTMORILLONITE (HOWER 1970)
                   Used by permission, see Copyright Notice
         Surfactant             Surfactant adsorbed (mg/g montmorilignite)
           Added
    mg/g montmorillonite              Cationic            Nonionic
100
200
400
600
1,000
1,500
97
188
351
451
510
528
99
192
321
412
512
540
     Three matrices were utilized by  Bowman  and Sans (1982) to  place  pesti-
cides on  soils.  The  pesticide matrices included:  1) aqueous solutions,
2) hexane-acetone  (95:S  volume/volume)  solvent, and  3) pure  acetone.    Two
levels of spiking were used with the  hexane-acetone  solvent, one at  5.0  ug/g
(low spike) and  one  at the level obtained with  aqueous equilibrium  isotherm
studies.   With the acetone matrix,  spiking was done at the  level  indicated by
the  aqueous equilibrium  isotherm  method.   Four  desorption  cycles were  used
with  two  pesticides of  different water  solubilities,  fensulfothion  (water
solubility = 2000 mg/1)  and  its related sulfide (f.  sulfide)  (water solubility
= 1.7 mg/1).    Three mineral soils and a muck  soil  were  used  to determine the
influence of organic matter  on desorption (Table 3-58).

     Figures  3-51 and  3-52  illustrate desorption  of the pesticides  as  func-
tions of  application matrix  and soil type.   For both pesticides  desorption was
greater  for  solvent  applied   pesticide  (hexane-acetone, and  acetone)  than
for aqueous applied  pesticide in the mineral soils.   Also an  obvious effect of
solvent matrix on desorption is evident for f.  sulfide. Less  f. sulfide was
desorbed  in the  acetone  treated  soil  than in  the  hexaneacetone  (high  spike)
treated soil.    This was not observed  for fensulfothion.   Thus the type of
solvent  also  appears   to  play  an  important  role  in  desorption behavior of
organic wastes.

     The muck  soil did  not show differences  in  desorption  to the extent
exhibited by the  mineral  soils.   This was true  for  both pesticides  studied.
However,  while the maximum desorption  of f. sulfide was  10  percent after four
desorption cycles (of the high  spike  hexane-acetone method),  60 to 70 percent
fensulfothion  was desorbed  from  the  muck  soil.  Desorption  was  also consis-
tently greater  for fensulfothion from  the mineral soils.   This would be
expected  for the more water  soluble fensulfothion.

     Thus  the  chemical matrix  in which  organic  constituents  are dissolved
may  have a very important effect on the subsequent  mobilization of  the

                                      176

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      TABLE 3-58.  PROPERTIES OF  SOIL  ADSORBENTS (BOWMAN AND SANS 1982)
                   Used by permission,  see  Copyright Notice
Adsorbent
                        Sand
                      TTTT
Organic
Matter
Sandy
Creek sediment
Sandy loam
Muck soil
91.5
71
77
52
1.5
22
15
34
7
7
8
14
0.7
2.3
3.9
36.7
6.9
6.5
6.9
6.3
                                                  Bondhead
                                                   Sandy
                                                    Loam
                                               0   1

                                         Oesorption Cycle
Figure 3-51.
Desorption of  fensulfothion from  four soils.   (   )  Low spike;
(  ) high-spike acetone;  ()  high-spike hexane; (	) equilib-
rium (Bowman and  Sans  1982).   Used by  permission,  see Copyright
Notice.
                                       177

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I
                        100


                        80


                        60


                        40


                        20


                         Q
Big Creek
 Sediment
                                              15005=304
                         Muck
                          SoTI
                      .  LS00.*142
                                    34Qi

                                     Desorption Cycle
Figure 3-52    Desorption  of  fensulfothion  sulfide from four  soils.   (   ) Low
              spike;  (    ) high-spike  acetone;  ()  high-spike hexane; (	)
              equilibrium (Bowman  and  Sans 1982).   Used by permission.,  see
              Copyright Notice.
constituents.    For typical  mineral  soils,  which  are  likely to  be typical
of hazardous waste sites,  insecticides adsorbed from  aqueous  solutions
would be desorbed to a  lesser  extent than insecticides adsorbed from organic
solvents.   Also,  less  water soluble constitutents may desorb to a  less extent
than  more  water  soluble  constituents.
     The work  of Brown  et  al.  (1983)
direct  application  to  hazardous  waste
results  in  clay  shrinkage,
chemicals  will be  reduced.
result.   If  the application
event  or  amendment  addition,
anticipated.    Also,  the  mass
                  and Bowman  and Sans  (1982)  may have
                   sites.    If  solvent-action  generally
       the  number  of  sites  available for  sorption of
        Less  total  sorption may  be anticipated as  a
       of  an  aqueous solution follows,  as  with a rain
        rapid  desorption of  poorly sorbed chemicals is
        transport of  chemicals  in  the soil  solution is
excerbated due to the  increased  permeability  of the soil as a result of  soil
shrinkage.  Thus  the effects of  solvents  in  hazardous waste  contaminated  soils
may  include two factors:  1) decrease  in  total sorption  to soils,  and 2)
increase in leaching potential through  changes in soil  structure.

Soil Catalysis

     Many chemical  reactions that occur in  soil  systems may  occur  independent-
ly  of  the  soil,  or may  be soil-catalyzed.   For example,  there  is a  rapid
                                      178

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release from soil of toxic methyl isothiocyanate after application of dazomet
or metham  to  moist  soil.  Catalysis of dazomet by  clay  surfaces  resulted  in
the formation of isothiocyanate  within  15-20 minutes of  application  to  soil
compost (Brady 1971).    The reaction generally increases with decrease in  soil
moisture.   This  is due to the  increased availability  of  63 in soil  with
decreasing moisture  content,  and  the 02 dependence of the reaction:

     metham                 methylisothiocyanate
                  02

     The  ability of clays to  catalyze  chemical  reactions  is  attributed  to
their strongly acidic  nature.  Heptachlor  is  rapidly degraded in the presence
of the acid clay attapulgite (pKa < 1).   Significant decomposition of several
substances, including:   1) chlordane,  2)  toxaphene,  3) heptachlor, 4) DDT,  5)
dieldrin,  and 6) endrin can  be achieved with  kaolinite  and attapulgite
(Fawkes et al. 1960).   The chemical 2, 3-dichloropropene  has been shown to  be
hydrolyzed up  to  three  times  faster  in moist soil than in  solution.

     Hydrolysis reactions  are important for attenuation of chemicals in soils.
Sorption-catalyzed  reactions  are  especially important  for  two  classes  of
chemicals, the chloro-s-triazines,  and  the organophosphates.   Hydrolysis  of
atrazine,  simazine, and propazine  to  their hydroxy derivatives  in soils
incubated at 30"C for 8 weeks was  reported by Harris (1967).

     The mechanism  of  chemical  degradation  of  atrazine   and  other  chloro-s-
triazines  is  believed to be explained  by the reaction of  triazines  with
carboxyl   groups  (COOH)  associated  with  soil organic matter.    Sorption  of
triazines occurs between protonated carboxyl groups and  triazine ring  N
atoms.    Hydrogen bonding of the  ring N and  a  soil  organic  matter  carboxyl
group  causes  electron  withdrawal,  in addition to  that  caused  by  electro-
negative  chlorine  and   nitrogen   atoms,  from  the  electron  deficient  carbon
atom enabling  soil water  to replace the chlorine groups.

     Chemical  degradation of organophosphates  involves primarily soil-sorp-
tion-catalyzed  hydrolysis  of ester  linkages.  Although  hydrolysis   leads  to
degradation, the  hydrolysis products may exhibit pesticidal properties (Cowart
et al.  1971).   The most important factors  controlling rate and product forma-
tion include pH (Faust  and Suffet  1966) and sorption. Degradation of diazinon,
ciodrin,  and malathion  occur  by chemical  hydrolysis.   While malathion  degrada-
tion may be chemical or biological, chemical hydrolysis is  complete before the
biological  lag phase  is complete (Konrad  et  al.  1969).   Hydrolysis  in  soil
systems  is  sorption catalyzed.    Specifically, sorption  of  organophosphate
insecticides  through  complexation  by soil-bound  cations  is  the  suggested
mechanism for  sorption-catalyzed hydrolysis.

     Malathion  degradation half-lives were 6-8  hr  in  soil  systems at pH  7.
First  order kinetics of degradation were observed.   Results  of Hindin (1963)
suggest that  in  alkaline soils  (pH 8), hydrolysis  of malathion may  be  base
rather  than sorption catalyzed.

     It has been  suggested  that  the extent of  sorption-catalyzed hydrolysis
of chemicals  may be related to  susceptiblity to  undergo  acidic or basic
hydrolysis in  soil-free systems (Guenzi 1971).

                                     179

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Polymerization

     Organic  compounds  added  to soil systems  often  react with  soil  oragnic
matter to  form complexes.   The covalent binding  of the pesticide  class of
organic chmicals to  soil  humic material  is discussed  by  Bartha  (1980).   For
example,   3,  4-dichloroanil ine,  a  principal residue of  several  phenyl amide
herbicides,  exhibited  a half-life  in  soil at  500 ppm  as  the humic  acid-
dichloroaniline (HA-DCA) complex of 693 days.   The  addition of aniline at 1000
ppm to  the HA-OCA  containing  soil   decreased  the  half- life, based  on  first
order kinetics, to 178  days  (You et  al .  1982).  Incorporation of substituted
aniline compounds  into soil  humic material may  occur  through the attachment of
substituted anilines  to  the  quinoidal  subunits  of soil  humus  (You et al . 1982,
Hsu and  Bartha 1976, and Parris 1980).   Thus although  the  recalcitrance of
compounds may  increase  in the  soil  system  through polymerization reactions,
addition of analogs  to  the  system may significantly reduce  the  half-life of
constituents   and  increase  degradation.   Results  of  chemical  incorporation
of  constituents  into  soil  humic  material  through  polymerization  and  sub-
sequent  effects  on  biodegradation  are   sometimes  confused  with  the effects
of  physical  sorption  of chemical  constituents  on  biodegradation  rate  and
extent.

MODELING THE  BEHAVIOR OF WASTE
CONSTITUENTS  IN SOIL SYSTEMS

Transport Models

     Transport models  are  important prediction tools for  assessing  the
fate of  organics  in  the  soil  environment  and the potential  for groundwater
pollution.  Transport models  in principle consist of  two parts:   1) a water
flow model, and 2) a  solute transport model (Selim and  Iskandar 1981, Rao and
Jessup  1982).  In  this section one dimensional  transport models  will be
described and  plant  uptake  will  be  assumed  to  be zero.  The water flow model
may be expressed as:


     f  -it (-Q)  $>                                                 (3-so)


where  0  is  the volumetric  water-soil  content,  K is  the  hydraulic conduc-
tivity,  x  is  the  soil  depth,  and  H is  the  hydraulic head.   Equation  3-50
can also be expressed as:
by substituting H =  h  +  x,  where h is the pressure head and D(Q) is the  soil
water diffusivity, and a(Q ) = -k(6)^i.   The term $ is found from the soil-
water characteristic,  which is  a  functional  relationship  between soil water
content (e) and the pressure head (h).  However,  the  soil-water characteristic
is  not  a  unique  relationship,  and  it  exhibits hysteresis  (Nielsen  et   al .
1981a).   That  is,  the  response  is different depending on whether the  soil  is

                                      180

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in a wetting or drying  cycle (Figure  3-53).   The  solute  transport  model  can  be
derived for a "representative elementary value"  (REV) of  a  porous medium.   In
this REV  level it  is  assumed that  the variability  in  medium properties  is
minimal (Bear 1972).  The solute  transport  for REV is formulated  as

where Dn  is  the hydrodynamic dispersion  coefficient,  c is the  solution  con-
centration of solute,  S  is the amount  of solute adsorbed per unit  weight  of
soil, and Qi  represents source and sink  terms.   Sink  terms  include degradation
(chemical  and/or  microbial),  volatilization,  decay,  and  any  other  removal
mechanisms.   The models  for  describing degradation  and  volatilization  are
discussed  in  other  sections  of  this  report.    The hydrodynamic  dispersion
coefficient is  composed of two components:   1)  mechanical dispersion  and  2)
molecular diffusion.   Mechanical  dispersion is  caused  by:   1)  velocity  dis-
tribution within each  pore,  i.e., the  velocity  of  fluid is  zero  at  the  soil
particle  surface  and  increases away  from the particle surface,  2)  velocity
change  due  to  pore  size  change,  and  3)  continuous fluctuation  in  velocity
direction with respect to the mean direction of  flow.   Molecular diffusion  is
caused  by the  concentration  gradient,  i.e.,  Pick's law  (the concentrations
tend to diffuse from  high  to low concentration  regions)  (Fried  1977).   The
hydrodynamic dispersion coefficient  is the  sum  of  the  mechanical  dispersion
and molecular diffusion (Dm)  (Fried and  Combarnous 1971):

     Dx = avn +  Dm                                                      (3-53)

where the second term is  the mechanical  dispersion,  v is interstitial velocity
(Darcy's flux divided by the  water content), and  a  and  n are  constants.  When
the soil is unsaturated a,  n,  and  Dm  are functions of soil-water  content (Yule
and Gardner 1978, Kirda et  al .  1973).  For  saturated conditions  n is assumed
to be  1, and  a is defined as dispersivity (Freeze  and  Cherry 1979).   Hydro-
dynamic  dispersion relationships  with interstitial velocity were discussed  by
Fried and Combarnous (1971),  Fried (1977),  Biggar and  Nielsen (1980),  Nielsen
et al .  (1981b),  and  Gelham and Cherry.  (1982).   It should be recognized  that
the  hydrodynamic  dispersion  coefficient  and  the  interstitial  velocity  are
highly  variable  in  the field (Nielsen  et al .  1981b).    Figures  3-54  and  3-55
show the skewed  distribution of the interstitial  velocity and  the hydrodynamic
dispersion coefficient for  360  field  observations (Biggar  and Nielsen  1976).
The practical  significance will  be discussed later in this  section.

     The solution of the solute transport equation  is  possible  if the spatial
and temporal distribution of  water content (0)  and  interstitial  velocity (v)
are known with  appropriate boundary conditions (Table 3-59).   Under transient
flow conditions  the  distribution of 0 and v can be determined.  Finite differ-
ence methods have been used for solving transport equations under unsaturated
conditions (Bresler and Hanks 1969, Bresler  1973, Kirda et al .  1973, Wood and
Davidson 1975, Tilloston  et al .  1980).  Selim (1978)  has used  a finite differ-
ence  method  for  multilayered  soil   under  unsaturated  flow  conditions  with
reactive  solutes.   Gureghian  et   al .  (1979) have  also solved  the  transport
equation  under  transient  unsaturated  flow conditions  for  a   layered  soil.

                                      181

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                              MATRIC POTENTIAL
Figure 3-53.
Soil-water characteristic  relating the  volumetric  water content
0 to the matric  potential  tym.  Hysteresis  properties are illus-
strated by the directional  arrows (Nielsen et  al.  1981a).   Used
by permission, see Copyright  Notice.
                         120-
                                        ode * 4.3 cm day"

                                          median2 20.3

                                              mean =44.2
                                       v (cm day"' )
Figure 3-54.  Frequency distribution  of values of the  pore-water velocity for
              a class  length  of 10. cm day1 (Nielsen  et  al.  1981b).   Used by
              permission, see Copyright Notice.
                                       IOO     200"

                                        D (cm1 day")
                                                       400
Figure 3-55.  Frequency  distribution of  values  of the  apparent diffusion co-
              efficient  D  for a class  length of 20  cm? day! (Nielsen et al.
              1981b),  Used by permission,  see Copyright Notice.

                                       182

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          TABLE 3-59.   BOUNDARY CONDITIONS FOR THE TRANSPORT EQUATION


1.0  Water Flow Boundary Conditions:
     1.1  Soil  surface boundary condition
          1.1.1  Water head boundary condition

                 h = ho(t)  at z = 0

          1.1.2  Water flux boundary condition


                 q(t>  = -D(0) || - K(9)  at  z=0

                 where q(t) = water flux - it can be either constant or time
                 dependent.

     1.2  Bottom boundary condition
          1.2.1  Impervious barrier
                 The flux is zero at the impermeable surface
                 (e.g. heavy clays)


                 -D(0) |2 + K(0) =0   at Z = L
                       oZ

          1.2.2  Soil  profile extends to a great depth (semi-infinite medium)
                 This boundary condition can be used in a well  drained soil

          1.2.3   Groundwater table

                  G=0s          Z =  L     t >  0
                  h  = 0          Z =  L     t 7  0
                 Qs  = saturation  water content

2.0  Mass Transport  Boundary Conditions
     2.1  Application of  waste


                 vC   = -0 D | +  vc     Z = 0     t < T
                  S        dZ

          where   Cs  = concentration of applied  wastewater
                  v  = flux  of wastewater application (cm hr-1)
                  T  = duration of application

          The same boundary condition can be used  for a rainfall  event

     2.2  Boundary condition at the bottom of soil  profile

             = 0     Z =  L      t  > 0
                                     183

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Finite element methods have  also  been used for  the  transport  eauation (e.g.
Duguid and  Reeves 1974,  Segol  1977).   Sykes et -al .  (1982) have used Galerkin-
finite element methods to  solve the transport equation under steady state flow
conditions.    Adsorption was  neglected and  Michael is-Menten  kinetics  (hyper-
bolic rate  law)  were used  to model the biodegradation of organics in leachate
from a landfill.   Recently Van Genuchten (1982) has compared different numeri-
cal  schemes  that  can be  used in solving one dimensional  saturated-unsaturated
flow and  solute transport  equations.

     Under  steady state flow conditions Equation  3-52 becomes:


      3c _ n  3 c      3c    p 3S                                           .  _.
     ft' Dh^T ' V^T'  9 3t                                           <3-54)

assuming  a  constant dispersion coefficient,  and neglecting source  and sink
terms.  Equation  3-54 can  be solved  if an appropriate relationship between S
and c  is defined  in  addition to  appropriate boundary and initial conditions.
Two types of  adsorption equations are  used  in  conjunction with the transport
equation:   1)  the equilibrium equation  and 2) the nonequil ibrium equation (Rao
and  Jessup  1982).    Equilibrium  equations  are  simply one of  the adsorption
isotherms described  previously  in  this  report.  The rationale in using adsorp-
tion  isotherm  in the transport equation  is that,  in most  cases, adsorption
reaches equilibrium  instantaneously.   In other  words,  the  sorption  rate  is
very  high compared  to the pore water  velocity.  The Freundlich  isotherm has
been  most often  used with the transport equation.   When  the Freundlich iso-
therm is  assumed  for adsorption Equation 3-54 becomes:


      R=D^-v                                                   (3-55)
where R is the retardation  factor,  which  is defined  as
     R = ! +      -                                                  (3-56)


The  retardation  factor  represents  the ratio  between  average pore  water
velocity  and  average  pollutant  front  velocity.    R becomes  independent of
concentration when  N=l,  i.e.,  when  the isotherm is linear.  The  use of
a  linear isotherm with the  transport equation gives rise to  an  analytic
solution  of the  transport equation (Lapidus  and  Amundson  1952).   The linear
isotherms have been used with the transport equation very frequently (Kay and
Elrick  1967,  Davidson  et al .  1968,  Davidson  and  Chang  1972,  Davidson and
McDougal  1973).    Van Genuchten  and  Alves  (1981)   have  compiled analytical
solutions  for  the diffusive  convective transport  equation  with  linear  iso-
therms for different  combinations of boundary conditions.

     The  assumption  of  a linear  isotherm appears  to  be  reasonable  at low
concentration ranges  for  organic constituents in soil  systems.   However, at
high concentration ranges,  i.e., close to solubility limits  (such conditions

                                      184

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may exist at hazardous  waste  sites), the exponent N of the Freundlich isotherm
is usually  less  than  one (Hamaker and Thompson 1972,  Davidson  et  al.  1980b,
Rao and  Davidson 1980).   In  fact  the  assumption of  a linear  isotherm at  high
concentration seems to  underestimate  the Teachable  concentration,  which  may
have dangerous  consequences  with  respect to  management of  hazardous  wastes
sites (Davidson et al.  1978,  Rao and Davidson  1979,  Davidson  et al. 1980b,c).
Also, deviations between  calculated and  observed  breakthrough  curves (BTC's)
often occur when  linear isotherms are used.  Van  Genuchten  and Wierenga
(I976a)   listed the experimental  conditions  under which  asymmetry (tailing)  is
observed in BTC:  1) unsaturated flow, 2) aggregated  media, and 3)  pore-water
velocity.  The inadequate prediction of transport  with  equilibrium  models  led
some investigators  to use a kinetic (nonequilibrium)  adsorption equation.   Two
approaches  were  used   in  developing  nonequilibrium  models:   1)  the use  of
chemical-process models  and  2)  the use  of  physical-process  models.   In  the
chemical-process models the  assumption  is that  adsorption  is  a time dependent
reaction and that  sorption equilibrium is not  attained instantaneously.
Travis   and  Etnier  (1981)  have  reviewed adsorption kinetic models  (see Table
3-29) In the second  approach  the assumption  is that sorption is instantaneous.
However, the rate  of  sorption  is  controlled by the rate of  diffusion  of  the
solute  to the soil  surface (Rao et al.   1980, Rao and Jessup 1982).

     Chemical-process models  can  be divided  into:   1)  one-site  models  and  2)
two-site models.   In  one-site models   the sorption  is  assumed to  be uniform
throughout the soil surface.   Lapidus and   Amundson  (1952) have  presented  an
analytical   solution  for  a  transport   equation  with  first order  reversible
kinetic   adsorption.  Oddson  et  al.  (1970)   have also  presented  an  analytical
solution for  a  transport equation with  first order kinetic  adsorption.
However, the authors neglected the diffusion term in the  transport  equation.
Lindstrom and Boersma (1978)  presented  an analytical  solution  for their  model,
developed earlier  (Lindstrom and  Boersma   1971),  coupled with first order
kinetic  sorption.  Hornsby and  Davidson (1973)  and  Hansel!  et al.  (1977)  have
also used  the kinetic  model that was developed by Lindstrom and Boersma
(1973).   The one-site  kinetic models showed much  improvement  of results
compared with equilibrium adsorption models.  However,  the  improvements  were
only limited to low pore-water velocities (Davidson and McDougal  1973, Hornsby
and Davidson 1973,  Van Genuchten  et al.  1974).   In two-site  models the
sorption sites  are  divided   into  two   types.   The first  site  type  is where
sorption occurs  instantaneously; with  the   second  type  of  site the  sorption
is time  dependent  (Cameron   and Klute 1977).    The  advantage  of a  two-site
model  over  a one-site  model  is  that two-site model  can better  simulate  BTCs
obtained  from miscible  displacement  studies (Rao  and Jessup 1982).  The
adsorption rate is defined as:
                  3t   -                                                 (3-57)

and

     3S2        N
     -5T  '  <[K2CN  ' S?3                                                 (3-58)
                                     185

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where the  subscripts  1  and 2  denote  the sites  type  1 and  type  2,  respec-
tively.   The  total  amount adsorbed, S,  is

     S = Si + S2                                                       (3-59)

The rate of change of S  is  found by substituting  Equations  3-57 and 3-58 into
the  rate  of  change  of  Equation  3-59.   The  expression  can be simplified
further  by setting N=l, and  assuming  that  F is the  fraction of sorption
site  1  of  the total sorption  sites.   The  rate of amount sorbed becomes:
                       - F)K C - S2]                                   (3-60)


The dimensionless form  of  the  transport  equation  is  (Van  Genuchten  1981):
        ov*i             <3L~   -I  3 Ci    oL,

        ~aT +  (RT " V TT = "P
    "i             C7W*   i O U^
n   -   j. f n    D  \   -     	_   	_                             / *3 1 \
Ki  at    \KT   *i '  ar  ~ "D    5    2T                             U-oi;
                                az*

where the transformed dimensionless variables are defined  as:



     Ri  = 1+r      '     RT = 1+f                               (3-62)

     T = vt/L         ;     Z = x/L                                   (3-63)

     w - kL/v                                                         (3-64)

          C- C1                   S2- (1 - F)KC1
     Cl  = CQ - C.      ;     C2 = (1 - F)K(CQ -  C^)                     (3-65)

T is dimensionless time,  L is  column  length,  P  is Peclet  number  (a measure of
convection  relative to  dispersion);  Cj  and  G are dimensionless concentra-
tions;  and  Ci and  C0  are the  initial  and  applied solution  concentrations,
respectively.  Van Genuchten and Cleary (1979) and Rao  et  al .  1982 have stated
that for w >_ 5 equilibrium conditions can be assumed.

     In  physical  process models  the liquid phase  in the  porous  medium is
divided  into  "mobile"  and  "immobile" regions.    Convective-dispersive solute
transport occurs  only in  the  mobile  region.   Adsorption  is  assumed to occur
instantaneously.    However,  the sorption  rate   is controlled  by  the  rate of
transfer between  the mobile and  immobile regions.   The rate  of  transfer
between the two regions  is driven by the difference in  the concentrations  (Van
Genuchten and Wierenga 1976, 1977).  This model   is formulated  as  follows:
9Cim
at
*\
- P n m
CmDm , 2
3x
V 0 - m
m m ox
                                                                       (3-66)
                                          III III ,,  C.     Ill III C'A


                                     186

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      [0  + (l-f)pk] - = a(C  -  C.  )                                  (3-67)
       m             o L       in    i ni

where  subscripts  m  and  im  denote the  variables  for  mobile  and immobile
regions,  respectively,  and  f  is  the fraction of  sorption  sites  in  contact
with the mobile  region.  The  dimensionless  form  of Equations 3-66 and  3-67
are:
                        ^f*       ^ \     ^C"
     D  	m   /D    n \ 	im. _ 1 	01  	01                            (3-68)
     Ri Tf + (RT " Ri) ~FT ' P  ^72    3Z                             u ba;
where the transformed  dimensionless variables are defined as follows:

      T = vmt 4>/L      ;    z  = x/L                                      (3-70)

     QS = (Qm +OiJ     ;    *  = (Vs)              -                    (3-71)
      I  (*  +    )     ;    RT  =  (i  - F)                                (3-72)


      P = (VnL/Dm)                                                      (3-73)


                                                                       (3-74)

                                r    _  r
                                im   wi                                ,, 7C-N
                       ;    C2  =  -r  TTT                                (3-75)
                                ^o    Li

$ represents the fraction of moisture content in the mobile region.  Although
the chemical  process model  and physical process model are conceptually differ-
ent, mathematically they are equivalent for given boundary and initial  condi-
tions.   The  validity of any of these models can  be proven experimentally if
independent measurements of the  parameters  of the models  are  available.
Unfortunately this  is not  usually the case.   Nonlinear  least  squares  have
been  used  to optimize the  parameter  values  in order to  make the difference
between the  model  and observed  points minimum.  Rao et  al .  (1980b)  used the
analytic expression  developed  to  calculate  the  transfer coefficient as  an
independent measure of the parameter.  The results showed good agreement with
the BTC's observed for-38ci-  and 3^0 over a wide range of pore-water veloci-
ties.  Based on theoretical  and  experimental  analysis, Rao et  al . (1980a)  have
found that the transfer coefficient is a function of system variables.

Limitations

     The parameters  for the models described above were  estimated  using
nonlinear least squares.   The  parameters were optimized so that the difference

                                      187

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between observed data and computed data  is  minimum.   Hence,  the validity of
the models  is   questionable  since  there  is  no independent  measurements  of
parameters for  the models.   In addition to  the unavailability of independent
parameter estimates, the  field  applicability of these  models is  further
limited by the  heteorogeneity  of most  soils.   As demonstrated in Figures 3-54
and 3-55  pore  water  velocities and diffusion  coefficients  in field measure-
ments are highly variable.   The pore  water velocity and the diffusion coeffi-
cient field measurements were shown to be log normally  distributed (Biggar and
Nielsen 1976,  Van De  Pol  et  al.  1977).   These  uncertainties in the parameters
will be  reflected  in decreased  accuracy of predictions.   Dagan and Bresler
(1979),  using   mixed  stochastic   and  deterministic  differential  equations,
attributed the  variability of concentration profile  in  the field mainly to the
uncertainty of  hydraulic  properties of the porous  medium.   In their  analysis
they neglected  molecular  diffusion  and  any  interaction between  the solute
and soil.   Recently,  Amoozegar-Fard  et al.  (1982)  used a Monte Carlo simula-
tion and  generated  2000  values  of C/C0  using the solute transport  equa-
tion.  They assumed normal distribution for In D,  In v, and the water filled
porosity, and  no  solute  interaction with  the  soil.   The results showed wide
differences between solute  profiles when deterministic values of v and D were
used.  The variability of D was much less important  than the variability of v.

     Therefore, according to  the  above discussions,  conceptual  models  have
been developed  but  not  much attention  is  paid  to  parameter evaluation.
Davidson  et al.  (1980)  have shown that  differences  between the  physical
nonequilibrium  model  Equations 3-68  and  3-69, and the  analytic solution of
Equation  3-55  for nonreacting  solutes  is negligible  (Figure  3-56).   Hence,
the simple  model  is  preferred  over the more  complicated in many situations.
For  the  purpose  of  site  assessment  for  in  situ  treatment, a  simple  model
has been  selected.   The  model chosen  is described in detail  by Enfield et
al.  (1982).   The model   includes  a first  order degradation term and assumes
a  linear  adsorption  isotherm.   The model  is a  one  dimensional   advective-
dispersive  transport  model  with   a linear  adsorption  isotherm, and  a  first
order degradation rate.   This model can be expressed as follows:


     !l = h--i-kic                                (3-76'


where  KI  is the  first order  degradation  rate constant and  the rest of the
terms  are as defined  previously.   Steady state unsaturated  flow  condition was
assumed in  this model.   The water  content is estimated such that mass conser-
vation holds.   Assuming  a  unit hydraulic  gradient,  the water  recharge  rate
(Darcy's  flux)   is equal  to the hydraulic conductivity.  The hydraulic conduc-
tivity is related to  water content by the following empirical  equation devel-
oped by Clapp and Hornberger  (1978):

     k *  (9/0s)2b+3                                                    (3-77)

where  k  is the  hydraulic conductivity,  Qs  is the saturation water  content,
0 is the  water content, and  b  is a constant.   Clapp and Hornberger  (1978)  have
estimated s and b for  a  range of  soil textures (Table 3-60).   Hence,  Equation
3-77 can  be used to estimate  the water content, knowing 0S,  b  and the recharge


                                      188

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        u
        u
1.0
          .0.8
        U
        z
        O 0.6
        U

        UJ 0.4
        < 0.2
        _J
        U
        cr  o
     NONADSORBED
     Q = 10 cm/day
                               AGGREGATE  MODEL

                               6 =0.26;9 = 0.14,P=9.6
                                M       A
                               DISPERSION  MODEL
                                = 0-4, P=1.3
                          234567
                            PORE   VOLUMES,   V/V.
                                                     8
Figure 3-56.   Calculated  relative effluent  concentrations  for  a nonadsorbed
              solute.   Solid  line  obtained using analytic  solution  of Equa-
              tions  3-68,  3-69;  dashed  line obtained  with  analytic  solution
              of  Equation  3-55 (Davidson  et  al.  1980).  Used  by permission,
              see  Copyright Notice.
           TABLE  3-60.   REPRESENTATIVE  VALUES OF HYDRAULIC PARAMETERS
                 (STANDARD DEVIATION  IN PARENTHESES) (CLAPP AND
                              HORNBERGER 1978)
                   Used  by permission,  see Copyright Notice.
Soil texture
Sand
Loamy sand
Sandy loam
Silt loam
Loam
Sandy clay loam
Silty clay loam
Clay loam '
Sandy clay
Silty clay
Clay
No. of
soils
13
30
204
384
125
80 -
147
262
19
441
140
b
4.05 (1.78)
4.38 (1.47)
4.90 (1.75)
5.30 (1.87)
5.39 (1.87)
7.12 (2.43)
7.75 (2.77)
8.52 (3.44)
10.4 (1.64)
10.4 (4.45)
11.4 (3.70)
s
cm
12.1 (14.3)
9.0 (12.4)
21.8 (31.0)
78.6 (51.2)
47.8 (51.2)
29.9 (37.8)
35.6 (37.8)
63.0 (51.0)
15.3 (17.3)
49.0 (62.1)
40.5 (39.7)
s
cm-Vcm^
0.395 (0.056)
0.410 (0.068)
0.435 (0.086)
0.485 (0.059)
0.451 (0.078)
0.420 (0.059)
0.477 (0.057)
0.476 (0.053)
0.426 (0.057)
0.492 (0.064)
0.482 (0.050)
                                      189

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rate.  The model  will  be  useful,  not in terms of the  absolute  estimate,  but
rather for  establishing  priorities  with  respect to  chemicals  and  chemical
classes that require treatment.   An  example of the application of the  model
and data  requirements are presented in Volume I of this report.


ATMOSPHERIC  ASPECTS  OF  IN SITU TREATMENT:
VOLATILIZATION  AND PHOTODE6RADATION

Volatilization  of Qrganics

     The  primary emphasis  in monitoring at sites of hazardous waste  contami-
nated soils  has been related to the impact  of these  contaminants on  the  water
environment.   Studies have concentrated on the movement of  metals, salts  and
hazardous organic  compounds  under  uncontrolled  hazardous  waste  sites  and
through soil  systems via groundwater  and leachates.   Information  obtained from
ambient  air  measurements  of the  Love  Canal  area and  from  the Hudson  River
Basin  indicate  that significant  concentrations  of  toxic  materials  can  be
released  from landfills and  dump sites,  often much greater than  emissions  via
water transport (Shen  and  Tofflemire  1980).   A number  of hazardous compounds,
ranging  from benzene  to  vanadium pentoxide, have been identified at  un-
controlled hazardous waste  sites  in varying concentrations  as shown  in  Table
3-61,  indicating  that  air  releases  of  many  hazardous  compounds  from  these
waste sites  may be significant.

Volatilization  of Organic Contaminants--
     Although a  paucity  of  information  exists  relating  to  the modeling  of
organic  contaminant emissions from hazardous  waste disposal  sites, much
information  exists concerning the  volatilization of organics,  primarily
pesticides,  from soil surfaces.   General  definitions  of volatilization
include  the  loss  of chemicals  from  surfaces  in  the vapor  phase,  indicating
that  volatilization requires  the vaporization and  movement  of  chemicals
from a surface  into  the atmosphere above the surface.   The rate  of contaminant
volatilization  is a  complex  function  of  the properties  of  the contaminant  and
its surrounding environment.   The  driving  force  for  volatilization  is  derived
from  the  vaporized  chemical  in  the soil pore spaces,  and the  volatilization
rate  of  the  material  will  be  affected  greatly by  the adsorption  onto  soil
particles and  the  absorption or  solubility  of  the  compound within the  soil
organic matter  and within the soil water.

     For  organics in  soil   systems  Spencer and  Cliath  (1977)   indicate  that
the factors  affecting volatilization  include:

    1.  Contaminant  vapor pressure

    2.  Contaminant  concentration

    3.  Soil/chemical adsorption reactions

    4.  Contaminant  solubility  in  soil water

    5.  Contaminant  solubility  in  soil organic matter

                                     190

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TABLE 3-61.  HAZARDOUS CHEMICAL VAPORS DETECTED AT UNCONTROLLED  HAZARDOUS
                               WASTE SITES
            Chemical                        Number of Sites
         Benzene                                  5
         Hexane                                   1
         Toluene                                  6
         Dichloroethane                           1
         Acetone                                  1
         Tetrach1oroethylene                      1
         Xylene                                   3
         Methane                                  6
         Vinyl  chloride monomer                   3
         PCB                                      3
         Other VHO's and VNHO's                   2
         Dioxin                                   1
         Ozone                                    1
         lonizable vapors                         1
         Vanadium pentoxide                       1
         TCE                                      1
         THC                                      1
         Methyl fur an                             1
         Benzaldehyde                             1
         Bis(2-chloroethyl) ether                 1
         Thorium                                  1
         Radium                                   1
         Methylene chloride                       1
         Trichloro ethane                         1
         Phenol                                   2
                                   191

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    6.   Soil temperature, water content, organic  content,  porosity,  and  bulk
        density

The major contaminant  property  affecting volatilization is its vapor pressure,
while the major environmental factors affecting the contaminant's vapor
pressure  are the  soil/water  and air/water partition  coefficients  that  exist
for the  various  soil/water/air environments  within  the  soil  system.   Addi-
tional  complexity  results  if the contaminant is added  along with an additional
adsorbing  fluid such  as  oil  in refinery  wastes,  where partitioning of  the
contaminant between  the  oil/soil, oil/ water, and oil/air phases would also be
expected  to affect the volatilization or vapor pressure  of  the volatile
compounds.

 Equilibrium Chemical  Partitioning--
     The  tendency  of  a  compound  to  migrate  from  one environmental  medium
to  another  is  a function of the  driving  force to  reach  equilibrium between
media,   and  is  related  to the  compound's  chemical  potential  energy or  its
fugacity.   MacKay  (1979)  originally  proposed  the  fugacity approach  for  com-
pound partitioning  as  an indication  of the  potential fate of  compounds  re-
leased  in multicomponent environments.  Further development of the equilibrium
partition approach has been  presented  by McCall  et al . (1983) for estimations
of chemical partitioning based  on the:

    1.   Sol, sermon  constant  - Koc - "
    2.  Water/air partition  constant - KW = -^ - = 16 Q4 p^- =fj
                                             air

    3.  Bioconceatration  factor  -  BCF .
                                                          .


where

    T      =  temperature,  "K

    Cajr,  =  concentration of  the  chemical  in the air and water,
    ^water
              respectively, mg/1

    WS     =  water solubility, mg/1

    P      =  vapor pressure of pure  chemical  (mm Hg)

    M      =  chemical  molecular  weight,  and

    H      =  Henry's law constant

     Correlations between partitioning coefficients  have been  presented
by  a  number of authors and have been tabulated in Table        according to
chemical class.  These correlation equations are valid for nonionic compounds

                                      192

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and describe partition coefficients in  terms  of  a  compound's vapor pressure,
water  solubility,  and melting  point.    Knowing  the  comoound's  partitioning
among the various media allows the estimation of its equilibrium distribution
throughout the  environment,   and  indicates the  relative importance  of  each
medium as the contaminant  concentration  moves  toward an equilibrium level.

     A compound's potential  for  volatilization  from  aqueous solution is
indicated by  its air  to  water  partition  coefficient,   1/KW  =  H.    From the
expression  for  Kw  given above, volatility is seen  to increase as water
solubility decreases or vapor  pressure  increases.   Volatilization  from soils
is  also  affected by  soil sorption  allowing an  expression  for  volatiliza-
tion  from wet soils  to  be  developed  through  a modification  of the water
volatilization term  (Swann et  al.  1983):


     Volatility rate   -jr4                                          (3-78)
                          w oc

                          PM
                      (WS)TK                                           '(3--79)


     An analysis  of  a  compound's physical  properties in  the  above manner  will
indicate  its potential  for  volatility as compared to other  compounds of
interest.    McCall et  al  . (1983)  showed   that  tetrachlorobiphenyl  (Kw  = 2;
Koc =  32,500;  P  = 4.9xlO~4  mm Hg) has a large tendency to  volatilize  from
aqueous solutions due to  its  low Kw value,  even  with a vapor  pressure  five
orders of magnitude less  than  1,3-dichloropropene  (Kw  = 18, Koc  =  68,   P  =
25 mm  Hg),  yet  its volatilization  from soils is  less  than  that  of  1,3-di-
chloropropene because  of tetrachlorobiphenyl's large Koc value.

     Because  of  the  importance  of partition  coefficients in  estimating  con-
taminant  movement,  and the large number  of compounds of  concern, efforts  have
been made to estimate  partition coefficient values  based  on  rapidly determin-
able  surrogate  parameters.    Swann et  al. (1983)  have  presented  equations
relating  various  partition coefficients  to retention times obtained by reverse
phase high-performance liquid chromotagraphy  (RP-HPLC).  A  Waters  Associates
HPLC  system  was  utilized with  an 85:15  v/v  mobile phase  of methanol-water
pumped at room temperature at  1.0 ml/min.   Expressions for  the various parti-
tion coefficients of  interest based on  RP-HPLC  retention time  (Rt)  and  com-
pound melting point (MP) were  as  follows:

     In Koc =  3.446 In Rt  + 1.029                                       (3-80)

     In Kow =  5.505 In Rt  - 3.780                                       (3-81)-

     In BCF  *  5.147 In "Rt  - 6.977                                       (3-82)

     In WS =  7.618 In  Rt - 0.01  (MP-25) + 18.328                        (3-83)

Correlation  coefficients  for   the  above  equations ranged from 0.95 to 0.98,
indicating that  a rapid estimation of  compound partitioning  is possible based
on RP-HPLC data.   The equations  were presented  for  nine  pesticides;  benzene;

                                     193

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bromobenzene;  bibenzyl;  biphenyl;  2,2',4,5,5'-PCB; and  anthracene  and  cannot
be considered general purpose  relationships.   They do  suggest,  however,  the
validity of  using  RP-HPLC retention  for  partition coefficient  estimates  if
correlation  equations for  a specific  compound  class  are  developed  using  a
particular  RP-HPLC  operation.

Dynamic Vapor Movement Models--
     Evaluation  of  chemical  characteristics  using  equilibrium  concepts  as
described above  indicate  gross  chemical  movement  potential  but  do not  provide
information  concerning  the rate of movement toward equilibrium nor the vari-
ation  of rates  with time.   Analysis of contaminant vapor movement  using
diffusion concepts provides this  time variant analysis for movement  through
soil  systems.

Volatilization from an Adsorbing Surface--
     Adsorption  of a  compound  onto an  adsorbing  surface reduces  its  chemical
activity, or fugacity, resulting in a  reduction in its vapor pressure  (Spencer
and Cliath   1977).  This  reduction in vapor pressure  decreases significantly
the vaporization rate of the compound.   This  fact invalidates  volatilization
equations based on compound  aqueous  vapor  pressure  measurements and  on  the
rate  of volatilization  of  a  model   compound  assuming nonadsorbing  surface
volatilization as  presented by  Hartley (1969):

         P   (M  )*
     Fh =~	^  '  Fa                                                 (3-84)
      b  P   (M  ) 2    a
          a v a'

where

     F   =   vapor  flux rate

     P   =   vapor  pressure

     M   =   molecular weight

     a,b =   model  compound and  volatilizing compound, respectively

     A  relationship similar  to  Equation  3-84  could be used  to estimate
volatilization from soil  systems if  vapor pressure measurements  of  the
compound in the  soil  are  determined.   Spencer  and  Cliath (1969, 1983)  describe
a modification to  a gas  saturation method they have developed which utilizes a
pesticide-treated  soil,  in place of  a  pesticide treated  quartz sand, in a test
saturator along  with a humidity control  device  for maintenance of soil mois-
ture  content  during  testing.   Diffusion  time variation  information  for  the
volatilizing compound can  then be obtained from Equation 3-84  if diffusion
variation of the model  compound is known.

     Further  complications  result  when  the  compound  is  soil   incorporated.
Under  soil  incorporation conditions, volatilization of the compound  in-
volves  the  desorption  of the  compound from liauid  layers  that coat  the soil
particles,  diffusion  through the  air filled pore  spaces within the soil column

                                      194

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to  the  air/soil   interface,  followed  finally by  the diffusion  from  the soil
surface  to  the  overlying  atmosphere  (Thibodeaux  1979).   Vaporization under
soil  incorporation  conditions  occurs  at  a  much  slower rate as  compared  to
vaporization from soil surfaces due to reductions in the vapor pressure of the
compound  and  the slow rate  of  diffusion through  the soil  column  to  the air/
soil  interface.   As volatilization occurs,  a concentration gradient  develops
between  equilibrium  and actual  concentration  levels in  all  phases resulting
in  a  driving  force for  continued  diffusion.  The  rate  of diffusion  declines
with  time,  however,  as the  concentration  gradient is reduced due  to  an ever
increasing  diffusion   path   length  to the   air/soil  surface  (Hamaker  1972).
Simplification of  this complex problem,  by  assuming  a  compound  concentration
at  the  soil  surface equal to  zero and  a  soil  column of  infinite  depth,  has
resulted  in relationships for mass  flux  rate with time  based on Pick's second
law of diffusion in the general form as presented by Mayer et al  . (1974):
            -
         (n ot)"2
                                                                        (3-85)
where

     F   =  component mass flux rate through the soil  surface

     Ds  =  soil diffusion coefficient

     CAO =  initial  component concentration

     t   =  time

Contaminant Advection 
     An  additional   source  of  contaminant  volatilization  from  soil  systems
is  an  advection process,  labeled  the "wick  effect"  by Hartley  (1969),  that
describes the net contaminant  transport via  a  large upward  diffusion of water
toward the  soil  surface  due to evaporation of  water  from  soil  surfaces.   The
impact of  this  advection term  will  vary  from  compound  to  compound  and  is  a
function of the  compound's  soil  adsorption  characteristics,  water solubility,
and  partition  coefficients  in  the  air,  soil, and  water phases.    A  simple
relationship for this flux term was presented by Spencer and Cliath (1973):

    F = Fw x c                                                          (3-86)

where

   Fw  =  water  mass flux rate

   c   =  component  concentration in soil  water

A complete  accounting  for the mass  flux  of  a volatile component  from  a  soil
system can then  be  written  using the summation of  Equations  3-85 and 3-86 to
account for flux due to diffusion and due  to mass  transport  via advection  with
evaporated soil  moisture.

                                      195

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Vapor Transport  from  Hazardous Waste Sites--
     The models  developed  as described above are limited in that they lack the
ability to include  intimate soil  and waste  interactions as occurs in hazardous
waste sites where  drums  of  chemicals  leak into soil  systems  and  around soil
particles.   To   accurately model volatile  organic  emissions  from hazardous
waste sites,  both the soil pore diffusion and soil surface diffusion phenome-
non must be considered, and means must  be provided  to predict diffusion as a
function of soil  and  diffusion length characteristics.

     Modeling of the  evaporation  and  diffusion  of chemicals  within  the
pore  spaces  of  soil  systems using  the concept  of a "dried-out" zone  was
presented by  Thibodeaux   (1979)  to  describe  soil contamination  from  liquid
spills.    In his  model,  soil  contamination to a soil  depth  of h was assumed,
with compound evaporation from  soil  surfaces,  vapor diffusion  into  soil  air
spaces,  and movement of  the  vapor up and  out  of the  air/soil  interface.   A
"dried-out"  zone develops  at  the air/soil surface which is relatively free of
adsorbed  contaminant  but through which vapors  from the  lower  level must
travel.   With time, this "dried-out"  zone increases in depth, correspondingly
reducing the contaminated zone to an ever decreasing  thickness, y.  The soil
column  is assumed  to be isothermal,  capillary action  is  considered minimal,
and soil adsorption of  vapor through the  dried-out zone along with biodegrada-
tion are also  considered negligible.

     Vapor diffusion  through  soil pores  in the "dried-out" zone is considered
limiting, resulting  in the following  expression  for  compound  mass flux rate
from the contaminated zone through the dry surface zone:


                                                                       (3-87)
where

     D/\  =  component  diffusion  coefficient  in soil  air spaces

     h   =  initial  depth  of  soil  contamination

     y   =  variable thickness of soil contamination  after onset of diffusion

     C/\* =    equilibrium  concentration of  component in  pore spaces  at the
            evaporating  plane

     CA.J = concentration of the  compound at  the  air/soil  interface

The  time  for  all of  the  liquid  to  vaporize  from  the  contaminated  zone was
given as:

             h m.
     t= -    * -                                                    (3_88)
                                      196

-------
where

     A   =  surface area of contaminated  region

     t   =  time for all liquid  to  vaporize.

     m^  =  mass of component  originally  in  the  contaminated  zone


Upon  complete  vaporization within  the  contaminated  zone,  diffusion  can  be
modeled  as  the diffusion  of  a  chemical  from  vapor filled  pore  spaces  that
are  saturated  to a  depth  of  h.   Analysis of  the multicomponent  continuity
equation  with  appropriate  boundary  conditions  results  in  an  expression  for
the  average  concentration   in  the  contaminated zone  at  time  t   (Thibodeaux
1979):
                         IT n=0'(2n+l)'
                                        exp
                                               DA(2n+l)Vt
(3-89)
where
     C/\  =  average compound concentration  in  the  pore  spaces,  and  other  terms
            are as defined above.
Thibodeaux  (1979)  presented,  a  graphical  representation  of  the  fraction  of
chemical  remaining,  F/\  =  C/\/C/\*,  versus  dimensionless  time,  log  (O^t/h^)
(Figure 3-57), allowing the determination of compound lifetime for pore
diffusion.   Total  decontamination time  is thus  the  sum of results from
Equation  3-88  for vaporization  time  and  Equation  3-89  for  vapor  diffusion
time.
     Refinement of the  "dried-out"  zone  approach to air emissions from  land-
farming  of  petroleum  wastes  has  been carried  out by  Thibodeaux  and  Hwang
(1982) and represents the  state-of-the-art description  for  the  volatilization
of organics from  land  treatment  operations.   This  model is  applicable to  the
estimation of  air  emissions from hazardous  waste sites with  slight modifica-
tions  as  discussed below.   The model  as developed  assumes  an isothermal  soil
column, no capillary action through  the soil  layer,  no  adsorption  in  the  soil
pore space, and no biodegradation of applied  organics within  the  soil  column.
The description of vapor  movement  through  the soil/waste matrix  is valid  for
surface or subsurface waste applications through the use of  surface  injection
depth, hs,  and depth  of  penetration  or  plow  slice depth,  hp.   As  applied
to hazardous waste sites,  hs=0 and  hp are  equated to the estimated  or  measured
depth of the contaminated soil layer.  Under  steady-state conditions,  the  time
for the intial mass applied to completely  volatilize is  determined  through  the
analysis  of   the  component vaporization  rate,  assuming  a   diffusion  length

                                      197

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                                     log (l4jf'V I
Figure 3-57.   Fraction  of contaminant  remaining versus  dimensionless  time
              from Thibodeaux 1979).    Used  by  permission,  see Copyright
              Notice.
varying from the  surface -i-nc-orporation  depth,  hs, at time t=0  to  a value of
the penetration depth,  hp,  at complete volatilization.   The average diffusion
length is:
     h  -h         h +h
                                                                       13-90)
the flux rate into  the  pore  spaces from Fick's first law becomes:

             
     A  "
                                                                       (3-91)
Equating F  to  its principal components  and  solving for the  lifetime  of the
diffusion reaction  assuming  a mass  concentration  at  the  air/soil  interface
equal to 0 yields an  expression for the  lifetime,  t, of the applied component:
         "
     t =
         2 A DA CA
                                                                       (3-92)
where
    CA  =  component concentration  within  the  pore  air  spaces

    MA  =  total  mass component volatilized

    A   =  applied surface area or  area of soil  contamination

 It  should be recognized that  M/\/A represents the waste application rate
 on the landfarming area if all  mass is  volatilized.   In waste  spills  analysis,

                                      198

-------
M/\ represents  the  estimated mass  of  component A  originally in the  contami-
nated zone, again  assuming  all  mass is  volatilized.
     Through mass  balance   relationships  the  mass  flux  rate  of  component  A
through the wet  zone-dry  zone  interface with appropriate boundary  conditions
can be presented  as:
                   D. C.
                    A  A                                                I-
                    MA
where
    t = time after waste application
     The component  pore-space  air  concentration  is  related to the  component
concentration within the applied  oil by equating the  rate of transport  through
the oil phase to that through the dry soil  column.   The transfer rate equality
takes the form:
where
     as  =  interfacial area per unit volume of soil
     D0  =  component diffusion in the oil  phase
     Z0  =  oil -layer diffusion length
     C-JQ =   component  concentration  on the oil  side  of  the  air/oil  interface
     y   =  average thickness of the  wet zone
The  concentration  of the  component  in  the air  and oil phases  within  the
soil pore space is related by Henry's law constant to yield:
     CA = HCCL                                                          (3-95)
where
     HC  =  Henry's law constant in molar concentration form
Substitution of Equation 3-94  into Equation  3-95  allows  for  the expression of
the  concentration  of the component  in  the soil  vapor  phase in terms  of  its
initial concentration within the oil  as:

-------
Hc
1 -  / AZ \
c kas ^v^l
Cio
                                                                       (3-95;
The expression  y(hp-y)  indicates the  impact of a lengthening dry zone
and is expressed  as:
y(hp - y) =
                            - 2h
                                                                       (3-97)
resulting in
CA =
H
/ 5 DAZ. \
1 + H A 
C ^ 2 , , 2v
\ D a ( h +h h -2h ) I
\os p ps s /
Cio
                                                                      (3-98)
     The relative  importance  of  the  oil  layer  diffusion  rate  is  highly
dependent upon the oil-layer diffusion  length,  Z0,  and the interfacial area,
as, which  should be  intimately  tied  to the  waste application  rate  and  the
nature of the soil in the soil system.  Thibodeaux  and Hwang  (1982) presented
equations for Z0 and  as  for  oil/soil  interactions that  result  in  either "film"
forms or "lump"  forms within the  soil  column.  Oil  interactions resulting  in  a
thin coating  around  hypothetical  spherical  soil particles  results in "film"
forms with  the following characteristics:
     2  -
            
                                                                       (3-99)
     as  =
                                                                 (3-100)
where
     dp =  particle diameter

     Pp =  soil particle density

      P =  oil density

     f  =  fraction of oil  in film form

                                      20C

-------
Soil  aggregation  results  in the  clumping  of  soil  particles  and causes  the
entrapment of oil  or contaminant "lumps" within  tne  soil  particle  aggregate.
Diffusion film  thickness  and  interfacial  area  expressions  for soil  clumps
assuming  an  orthogonal  arrangement  of  particles  surrounding  an oil  "lump"
yield:


     Z-                                                             (3-101)
                                                                      (3-102)
The fraction of pore  spaces  that  is air filled is  assumed to  be  50 percent,
yielding an estimated  f  value of 0.5.

     With  a  thin  oil  diffusion  length,  on the order  of soil  particle  size
thickness,  Equation  3-96 simplifies  to:

     CA = Hc Cio                                                       (3-103)

Transport between  the oil  and  air  pore  spaces  is  at  equilibrium  under these
conditions  and diffusion  in  the  air spaces limits  the  overall  mass transfer
rate from the landf arming area.

     The diffusivity of the  component  in  the  air  filled  pore spaces  is
related  to  that  in  air by  taking  into  account  the  reduction  in  molecular
diffusion  in a soil  medium due  to cross-sectional  area occupied by  soil
particles (porosity correction)  and  to twists  and  turns  in the diffusion path
due to  irregularities of the pore  spaces  within  the  soil column  (tortuosity
correction).  Mathematically  this  correction takes the form:
                                                                      (3-104)
      rv     i

where

     D/\. =  component  diffusion  in  air

        -  son porosity -  1  -
     T   =  soil  tortuosity

     With the use of  Equations  3-92,  3-93,  3-98,  3-99, 3-102, and 3-104, the
time  for decontamination  and the  rate  of  organic emissions  from hazardous
waste  sites  can  be  determined   using  the  Thibodeaux-Hwang  model, once the
following parameters  are  measured:   soil  parameters  including bulk density,
particle  diameter  and  particle density;  compound  parameters  including air
and  oil  molecular diffusivity and  Henry's  law  constant;  and operational

                                      201

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parameters  including surface injection and penetration or  plow  splice  depth,
surface area  of  application, mass application, and time.

     This  model  represents the  state-of-the-art  for  landfarm  air  emission
rate  (AERR)  modeling  and for  a  general  case of  soil  contamination from
spills  or  leaking  drums, volatilization  from contaminated  soil  without
the oil  film diffusion term  can  be  modeled  utilizing  partitioning  coeffi-
cients  described earlier.  The partitioning  between  soil organic carbon
and soil water  would  be  controlled  by  Koc  and between  the  soil  water  and
the soil air  pore  spaces by Kw.  Assuming equilibrium conditions  occur between
phases before volatilization begins results in an expression for  soil  air  pore
concentration:

     CA = CW/KW                          .                              (3-105)

where

    Cw  =    the  component  concentration  on the  water  side of  the  air/water
           interface

Following  the development of  an  expression  for  C/\  as  carried  out above
assuming the  rate of  diffusion  through  that  the  water  phase  and  dry  soil
column  can be equated and the  water film diffusion  length is small  yields
the following equation:

     CA = Ciw/Kw                                                      (3-106)

where

    C-jw  =  the  initial component concentration measured in the  soil  water

C-jw will represent  the measured value established based both on partitioning
between the  soil/water and  water/air phases  if equilibrium conditions  are
reached.

     In the  development  of the  above models,  the  air/soil surface  concen-
tration of the  contaminant was assumed  to  be  equal  to  zero due  to  surface
air transport of  vaporized components  away from the site.   Movement  in  both
the vertical   direction,  due to  vertical  turbulent  diffusion  as  modeled  by
the Thornthwaite-Holzman equation  (Thibodeaux  1979),  and the  horizontal
direction  due  to  advection,  result  in  contaminant  transport  away  from  the
diffusing  surface.  The integration  of surface flux  r^te models  for transport
through soil  systems,  with  surface transport models, enables the evaluation of
the impact  of micrometeorological  conditions  on the  emission and transport of
toxic organics from hazardous  waste  sites and allows an  evaluation  to be made
of ambient  air quality level  impacts  from hazardous w.v.e sites.

Factors Controlling  Contaminant  Volatilization

     In reviewing the models presented for prediction of contaminant volatili-
zation  from  soil  systems,  the  following  soil  and contaminant characteristics
can be  identified as significantly impacting compound volatibi1ity:

                                      202

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     1.    Soil  moisture  content,  for  compounds  with  low  K0-  and  Kw. values
when soil moisture  content is  low,  causing  an  increase  in  cif*jsion due to
water competition for soil  adsorption sites (Hamaker 1972, Spencer  and Cliath
1977, Thibodeaux 1979).  The  moael  parameter  reflecting this effect  would be
Henry's   law  constant,  Hc,   which  varies  with  vapor pressure  from  tne  rela-
tionship:
     Hc - H Cg ()


where

     Hc =  Henry's law constant  in molar  concentration  terms

     H    =  Henry's  law  constant  in  partial  pressure/molar   concentration
             terms

     P    =  total pressure

     Cg   =  molar gas density =  P/RT

     Po   =  component partial pressure

     R    =  gas 1 aw constant

     T    =  absolute temperature

An  increase  in  component partial pressure  would increase  Cg,  which in  turn
increases Hc, which  in turn  increases C/\,  resulting  in an expected  increase
in the mass flux  rate  F until greater  than  one monolayer  exists.  With greater
than a single water monolayer within the  soil  (high  moisture content), reduced
porosity affects becomes controlling.

     2.  Temperature,  causing an increase  in vaoor pressure, water  advection
rates,  soil/water/air  partition  coefficients, and  biodegradation rates  (Ha-
maker 1972, Thibodeaux 1979).

     3.  Soil  organic content, causing the partitioning between  the  soil/vapor
phase and a reduction  in compound diffusion  coefficient due to  a reduction  in
its vapor pressure (Hamaker  1972, Thibodeaux  1979).

     4.  Surface  air flow rate, causing an  enhancement of flux rates due  to
maintenance of minimal organic  and  water vapor concentrations above the  air/
soil  interface,  maintaining  the  driving  force for diffusion.   This  effect  is
reported to  be  of major concern  for  surface  applied  wastes  due to the  pore
diffusion limitations  that  exist for  volatilization from  subsurface  applica-
tions (Spencer and Cliath  1977,  Thibodeaux 1979).

     5.   Biodegradabil ity,   causing the  removal  of the  compound via  uptake
and metabolism thus reducing  its  volatility.   Degradation products  have
been  reported  to  be more  volatile   than  parent compounds  however  (Spencer

                                      203

-------
and Cliath  1977),  and may  potentially cause  an  increase  in  component  flux
rates.

     Other contaminant characteristics  such as  Kow,  Koc,  Kw,  BCF,  MP,  and
vapor pressure  affect  volatility due to  their interaction with  soil/  water
conditions within the  environment  and are  not  generally controllable.  Their
relationship  with  one  another  for a given compound will  indicate the potential
effect  of organic  amendment  addition  and  water addition  on volatility,  how-
ever, and can serve as tools  for contaminant management as will be discussed
in the  treatment section  of this  report.


Compound Photoreactivity


     Photooxidation is  the  use of  incident  solar radiation to carry out
photoreaction processes.   It  utilizes cost-free solar  energy  as  the driving
force for  reaction  but  suffers  from the  variable  supply  of  incident  solar
energy  and the attenuation of  UV  light as  it  travels through the atmosphere.

     Photodegradation  of  organic  compounds may  occur by  two  processes:  direct
photodegradation and sensitized  photooxidation.   In the direct photoreaction
process, each particle of  light, or quanta, excites  one substrate molecule.
Although many organic  compounds absorb light, their  adsorption is primarily in
the  ultraviolet  region,  rendering  direct  photodegradation  an   inefficient
treatment process  (Thorington  1980).

     In  the  sensitized  photooxidation process, sensitizing molecules absorb
light in  the visible  region  where there  is a wealth of  energy reaching the
earth's surface.  The electronically excited sensitizing molecule, or triplet
sensitizer,  then returns  to  ground  state by transferring  its excess energy to
molecular oxygen, resulting  in  the  formation  of singlet  oxygen.   Sensitized
rates of photolysis  are often  orders of magnitude greater  than those of direct
photolysis (Acher  and  Saltzman  1980)  and  are  also  characteristically photo-
oxidations,  whereas direct photolysis may  proceed by  a  variety of mechanisms
including isomerism,  dehalogenation  and dissociation.

     Singlet oxygen is a highly reactive species of oxygen  with a  lifetime of
3  psec  (Kearns  1971).   It  readily  attacks  organic  substrates,  yielding
oxidized photoproducts.   Spikes  and Straight  (1967)  stated that many classes
of  organic  molecules are  susceptible to  sensitized photooxidation.   Among
these are alcohols, nitrogen  heterocycles,  organic  acids, phenols, and poly-
cyclic   aromatic hydrocarbons.   Sargent  and  Sanks (1974)  concluded that: many
compounds found  in  industrial  wastes,  such  as phenols,  cresols, trinitro-
toluene,  and  unsaturated nitriles  should  also  be  susceptible to  photooxida-
tion.

     The  rate of  photolysis   is  influenced  by a number of factors  including
the  intensity  and  wavelength distribution  of  light  reaching  the  reaction
media,  their  diurnal  and seasonal  variations, the  absorption  spectra of the
contaminant  or   photosensitizer, the  concentration  of  reacting  compounds,
and  the  energy  yield produced  during photon  absorption.   Additionally, the
nature of  the media  in  which the  reaction  takes place and the  interactions

                                      204

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between  the  contaminant  and  its  surroundings  nas  a  Tiajor  effect on  pncto-
cnemical  reactions  as  will  be  discussed briefly below.

Photolysis in Soils--
     The   evaluation of  pesticide  reactivity has  been  of primary concern  to
past investigators  due to  the  loss  of  effectiveness  of  pesticides  unaergoing
photooxidation,  and both direct and  sensitized  photolysis have  been  observed
for  pesticides  in  aqueous, soil,  and  vapor phases  (Miller and  Zepp  1983).
Although  the occurrence of  the soil photoreaction of adsorbed  chemicals  has
been identified, the  importance  of this  reaction  as compared  to aqueous  or
vapor photoactivity  and  the  reaction  pathways  through  which  the  reactions
occur,  have  not  been  identified to  date.   General  soil  characteristics  in-
cluding  soil particle  size,  organic  content,  mineral composition, light
absorption  characteristics,  and moisture  content  have  been   identified  as
affecting the nature  of  photodecomposition  products  and the rate and  extent
of the  photoreaction of some pesticides (Miller and Zepp 1983).

     The   relative  importance  of the photooxidation  reaction  of a  chemical
on or within a soil  will  depend  to a large extent upon  its  partitioning
between  the air/water/soil  media within  the soil  system.   The  soil/air
distribution coefficient,  K$/\,  can  be  calculation  from  other  constants  as
follows  (Lemaire  et  al . 1982):
where

    '-soil  =   concentration of chemical in wet soil on a dry basis,  ug/g

    Ca-jr  =   concentration of chemical in air, ug/cm^)

    r     =   weight of soil /unit weight of water

    KQ    =   soil/water  adsorption coefficient,  vg/g

Once partitioning  is  determined,  determination  of the  importance of  volatili-
zation or mobility to the  groundwater  may be made.   Soil  photodecomposition
will be of concern if the model  compound  remains relatively stationary within
the contaminated soil.   Soil  strongly  absorbs  incident light  energy and
continuous soil turn  over  may  be necessary  to expose adsorbed chemicals  to
solar radiation.

     Soil  organic content  would  be  exoected  to  affect  the  partitioning  of
chemicals  between  the soil  organic  material  and the soil  water.   Partition-
ing within  soil  organic matter reduces  the availability of the  compound
for photodecomposition  reactions  as shown  by  the  reduction  in  the  photo-
conversion of parathion  to  paraoxon  as  the organic matter in  soil  increased
from 0.1  percent to 4.2  percent (Spencer et  al .  1980).  Additional soil
characteristics such  as  transition  metal  content (Nilles and Zabik  1975) and
soil pigment  content  (Hautala 1973)  have also been  indicated  as  affecting the
photochemical  reactions taking place within a soil system.

                                     205

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     Moisture  content  is  an  additional  parameter  affecting  the relative
distribution  of  a  compound within  the  soil/water/air matrix  within  a  soil
system and would be  expected  to  affect contaminant  photolysis  accordingly.
Burkhard   and  Guth   (1979)  reported  that  photolysis  rates  of  profenfos  and
diazinon  increased  slightly as dry soils were  amended  to  12 percent moisture
content.    Hautala  (1978)  found a significant  decrease in  the  photolysis  of
carboyl  in wet soils  as compared to dry soils,  while  the  photolysis of  para-
thion was  independent  of moisture content.

     Photoreactions  of  halogenated   aromatic  compounds   have  also recently
been  of interest because  of a 2,3,7,8-tetrachlorodibenz-p-dioxin  (TCDD)
release  near  Seveso,  Italy,  in 1976 (Choudhry and Hutzinger 1982).   Photolysis
of TCDD  on soil surfaces was reported  by Crosby et al . (1971) in the presence
of suitable hydrogen  sources  in  the  form of polar solvents, and  Plimmer  and
Klingeble   (1973) indicated  that  methanol  used  as  a  solvent for  TCDD photo-
oxidation  experimentation  also  acted  as a  hydrogen  donor  in the  photolysis
reaction.   Investigations  of  the use of  alternative  hydrogen  donors for  in
situ  treatment of  contaminated  surfaces in  the  Seveso area was  reported  by
Wipf  et  al. (1978).   Solutions  of 80  percent olive oil  and  20  percent cyclo-
hexane at  350  1/ha  and 40  percent aqueous  emulsion with  4 percent biodegrad-
able  emulsifying agent  at 400 1/ha  were found  to  produce a  thin  film  on
vegetation and  other smooth  surfaces to provide a maximum reaction surface for
TCDD photolysis.   Under laboratory conditions,  the  oil  and emulsion solutions
reduced  the half life of TCDD by a factor of 25 when  irradiated  with  light  of
approximate solar wave-length distribution.   Liberti  et  al . (1978) reported
that  a 1:1 solution of ethyl  oleate and xyl ene used  as  hydrogen  donors  also
resulted  in comiplete TCDD  degradation  on building  surfaces in approximately 1
hour at  2m W/cm^  and 72 hours  at 20 yW/cm^ light intensity.

     Despite  the isolated  observations  of  soil  photodecomposition,   little
substantive information exists to allow accurate predictions of  the importance
of soil  surfaces on  general  chemical photodecomposition.  As Helling  et  al.
(1971) indicated in 1971 and  Miller  and  Zepp (1983)  repeated 12 years  later,
the effects of soil sensitization,  reaction quenching,  radical  formation,  and
light screening  and  the  soil  characteristics such as  particle  size,  organic
content,  and  temperature which  alter  these  effects remain poorly understood.
A great deal of  additional  basic  data is needed  if soil  photolysis rate  and
magnitude  predictions  are to be  possible in the future.

Photolysis in  Air
     Because  of the relatively high  volatility of  pesticides and their  trans-
port by  the air medium, vapor  phase photochemistry of these compounds  has been
studied  extensively.  Reviews of general photooxidation mechanisms for  pesti-
cides have been presented (Crosby  1971,  Plimmer  1971)  and  indicate  that
oxidation  is  the most  widespread reaction mechanism of pesticides under normal
environmental  conditions.   Vapor phase studies  have been hampered, however,  by
a lack of  general experimental  protocol  for  reactor design, reaction kinetics,
light source  selections,  and photoproduct collection and analysis.

      Seiber et al.   (1975)  described  methods for evaluating vapor phase photo-
decomposition of trifluralin on  a  lab and  field  scale,  identifying  four
photodecomposition products  of  the parent  compound.  The  decomposition

                                      206

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products  were also  found within  the  soil matrix,  preventing  an absolute
identification of  them as  vapor  phase  products  or  volatilized  soil  phase
products.   Definite  vapor  phase production of photodegradation products of  DDT
(Crosby and  Moilanen 1977), and  trifluralin  and parathion  (Woodrow et  al .
1978)  have been observed in the  laboratory.  Woodrow et  al .  (1983) have
recently reviewed pesticide vapor-phase photochemistry and  presented  informa-
tion concerning observed photochemical  vapor phase  reactions  under  laboratory
and field  conditions for  a  number  of additional  pesticides as  shown  in  Table
3-62.   Some compounds require ozone,  an hydroxyl  radical,  or  hydrocarbon free
radicals  to photoreact while others  display a reaction rate  enhancement
in the  presence of  an  oxidant  (Table 3-62).  Pesticides  not  amenable  to
photodecomposition  included  toxaphene,   methyl bromide,  and sulfuryl  fluoride
(Vikane).

     Polynuclear  aromatic  hydrocarbons  (PNA) are known to readily  decompose in
the air medium  upon  reaction with  ozone, NOX and  SOX (NAS  1972).    PNAs  are
not readily volatile  as  a class  due  to their partitioning  into the soil
medium, making  vapor phase  photodecomposition  of these  materials  in  soils
under  ambient conditions an  insignificant pathway for their degradation.

     Information  regarding  the  photooxidation  of  other  organic  compounds
within the vapor  phase  is  generally lacking but information from the pesticide
investigations indicates that major photoreactions within the  atmosphere  are
secondary reactions,  i.e., reaction of the model  compound with photochemical ly
produced reactive species  such as radicals, ozone, singlet oxygen, etc.   The
major  secondary reactions that occur are those  between these  organic  vapors
and the OH radical  or  ozone, of  which the OH radical is  the  photoactive
species of  greatest  reactivity  (Laniaire et  al .  1982).   The international
standard hydroxide  radical environmental  concentration of  4x10^ molecules/cm^
(Lamaire et al . 1982) provides a basis  for  estimating  lifetimes of compounds
within the atmosphere if reaction rates  of the compound, or its  homologs, with
the hydroxide radical  are  known.

    The half life of  the chemical in air may be determined  as  follows:

    1.   The reaction  rate  expression takes the form

    dC/dt = -kohKOH-lenv [C]                                         (3-109)

where

    dC/dt    =   rate of compound decomposition,  mole/sec

              =   bimolecular  hydroxide radical  rate  constant,  I/mole-sec
     [H"]env  =  environmental hydroxide radical  concentration,  4xl05
                molecules/cm3 = 6645xlO~19 moles/cm3

     [C]       =  component concentration, mole/cm3

     Integration of Equation 3-109 yields:
                                     207

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TABLE 3-62.   PESTICIDE  PHOTOCHEMICAL REACTIONS IN THE  VAPOR-PHASE
                (SUMMARY) (WOODROW ET AL. 1983)
            Used by permission,  see Copyright Notice
Chemical
Trifluralin
Parathion
Folex
DEF
Molinate

Chloropicrin
Aldrin
Dieldrin
DDT
DDE
Telone

Tetrachloro-
ethylene
Reaction observed in
lab field
yes yes
yes yes
yes
yes no
yes no

yes yes
yes
yes
yes
yes
yes

yes
Effect of
oxidant Major pathway
rate enhanced -NR2 - -NH
/ R
rate enhanced P -*S * P -*0
P(III) * P(V)0
required P(SR)0 - P(OH)0
required -CH2N- ->- -C(0)-N-
^ N-C(0)-S-J N-H
C13C-N02 -> C1-C(0)-C1
Xc = cx^>'-xc"
* photodieldrin
^CH-CC13->=CC12
>=CC12 -^C=0
required ^Tc=CHCl * ^CH-
C(0)-C1
^C^CL.^CCl-
                                                    C(0)-C1+C1-C(0)-C1
                                   208

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     In C/C0 = -k0H-[OH']env t                                         (3-110)

     2.  Component half life occurs when  c/c0  =  1/2  therefore

     In 1/2 = -0.693 = -koH[OH]env ti/2                              (3-111)

     ti/2 = 0.693/(kOH'[OH0]env)                                        (3-112)
Table 3-63  contains  a number of kgn0  values  for  various compounds in  air  as
presented by Lamaire et al .  (1982)  and Cupitt  (1980).   Additional  krj^0  values
will be required to  allow  the evaluation of atmospheric  residence  time  of the
full  range  of  materials   anticipated  to  be  generated  from  hazardous  waste
si tes .

Biological Interactions--
     Biological interactions in  terms  of enhancement  of volatility  of  biologi-
cal metabolic end products,  and the impacts of photodecomposition  products  on
biological activity become important in the  evaluation  of the  significance and
applicability  of  vapor phase  reactions  for  the  treatment of  materials   at
hazardous waste sites.

     The major  evaluation  of photodecomposition  products has been related  to
atmospheric reaction  of ozone,  NOX and  SOX  with the numerous hydrocarbons
found  in  urban air.    These  analyses  are  concerned with  the  impact of the
oxidizer/hydrocarbon  reactions  on  photochemical   smog  production  (National
Academy of  Sciences  1976).   Of  concern,  from  a hazard mitigation  standpoint,
is  the  production  of  hazardous  compounds   as  photodecomposition products  of
parent compounds of less hazard.   Such  occurrences  have been documented,  e.g.,
aldrin photooxidation to  the more  toxic  doeldrin  and paraoxon formation from
parathion (Crosby 1971) along with  the detection  of  phosgene from the  photo-
oxidation of chloropicrin,  and  the formation  of  PCBs  from the  photoreaction
of  DOT  (Woodrow et  al . 1983),  and the  potential  for  such occurrences with
additional parent compounds would be expected  to be  high.   Full  evaluation  of
the potential   for  hazardous photodecomposition product formation is not
possible  at  this  time  due  to  a lack  of  general   information  related to the
nature of photodecomposition products  formed,  and  further research is  needed
in this area.

     Studies of the  enhancement  of  compound  volatility  due  to  biological
activity are few and  a general  lack  of  information  exists.   Studies concerning
the enhanced volatility of mercury from soils  due to biological  activity have
recently  been   reported (Landa  1978,  Rogers  and McFarlane 1979)  and only
through more research related to microbial degradation/vapor phase  interaction
will an understanding of this process be obtained.

     The  use of photochemical reactions  for  the  enhancement of  compound
biodegradation   is an  additional  area  of  interest  for  hazard  mitigation from
hazardous  waste sites.   The major photolysis process  in  the  vapor phase  is one
of compound  oxidation and  it would be expected  to  aid  in  microbial  degradation
through the oxidation of  resistant  complex  structures  (Crosby 1971,   Sims and
Overcash 1983).  Information regarding this aspect of the  vapor phase  photo-
lysis  process  is also lacking and research related  to  aqueous phase photolysis
microbial  degradation enhancement  presently underway  (Oupont  and  Sims  1983)
may shed light  upon  its  usefulness  as a treatment option  in  soil  systems.

                                     209

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TABLE 3-63.  RATE CONSTANTS FOR THE HYDROXIDE RADICAL REACTION  IN AIR WITH
           VARIOUS ORGANIC SUBSTANCES, Kni,0 IN UNITS OF  /MOLE-SEC
             (ADOPTED FROM LEMAIRE ET ALVH(1980) AND CUPITT  (1980))
              Substance                             log kQ 0
                                                       air
        Acetaldehyde                                  9.98
        Acrolein                                     10.42
        Acrylonitrile                                 9.08
        Ally! chloride                               10.23
        Benzene                                       8.95
        Benzyl chloride                               9.26
        Bis(chloromethyl)ether                        9.38
        Carbon tetrachloride                         <5.78
        Chlorobenzene                                 8.38
        Chloroform                                    7.78
        Chloromethyl methyl ether                     9.26
        Chloroprene                                  10.44
        o-,m-,p-cresol*                              10.52
        p-cresol                                     10.49
        Dichlorobromobenzene*                         8.26
        Diethyl ether                                 9.73
        Dimethyl nitrosarnine                         10.37
        Dioxane                                       9.26
        Epichlorohydrin                               9.08
        1,2-epoxybutane                               9.16
        Epoxypropane                                  8.89
        Ethanol                                       9.28
        Ethyl acetate                                 9.06
        Ethyl propionate                              9.03
        Ethylene dibromide                            8.18
        Ethylene dichloride                           3.12
        Ethylene oxide                                9.08
        Formaldehyde                                  9.78
        Hexachlorocyclopentadiene                    10.55
        Maelic annydride                             10.56
        Methanol                                      5.78
        Methyl acetate                                3.04
        Methyl chloroform                             6.36
        Methyl ethyl ketone                           .-.32
        Methylene chloride                            7.93
        Methyl iodide                                 6.38
        Methyl propionate                             8.23
        Nitrobenzene                                  7.56
        Nitromethane                                  8.81
        2-nitropropane                               10.52
        n-nitrosodiethylamine                        10.19
        Nitroscetpylurea                              9.89
                                     210

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                  TABLE 3-63.  CONTINUED
      Substance                             log k
                                               ai
n-propylacetate                               9.41
Perch!oroethylene                             8.01
Phenol                                       10.01
Phosgene                                   nonreactive
Polychlorinated biphenyls                    <8.78
Propanol                                      9.51
Propylene oxide                               8.89
Tetrahydrofuran                               9.95
Toluene                                    9.52, 9.56
Trichloroethylene                             9.12
Vinylidene chloride                           9.38
o-,m-,p-xylene*                               9.98
                            211

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                                     2-15

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                                  APPENDIX A

               PARAMETERS FOR ASSESSING SOIL/WASTE INTERACTION


Compound Name:  Acenaphthene

Compound Properties:                                                Structure

M.W.           154.2    Water solubility    3.47 mg/1
M.P.            96.2    Log Kow             4.33
B.P.                    Chemical class
Sp. gr.                 Chemical reactivity
Vapor pressure 2.0xlO"2 torr (20C)

	Adsorption in Soils	

Adsorption Parameters     	Soil Properties	

                                                       Percent (%)
                  Vir
_pH	    CEC       QC        Sand      SiltClay
                             Degradation in Soils
  Degradation Parameters      _   _ Soil Properties __
                                     Mo is-
                     Initial  Temp,  ture                    Percent (%)
        KS      n     cone.    C    _  pH    CEC    PC   Sand  S i 1 1 ~CTay
       "OTTTS           500
0.3    2.81              5    15-25
                           Volatilization in Soils
Volatilization Parameters        _     Soil Properties __
                                          Moisture   Bulk     Temp.
                                 QC (%)   _  Density    C     Porosity

                                       246

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Compound Name:
                Aldicarb [2-methyl-2-(methylthio)-propion aldehyde
                0-(methylcarbamoyl)oxime]
Compound Properties:

M.W.     162.2
M.P.
B.P.
Sp. gr.
Vapor pressure
                                                                      Structure
                                Water solubility
                                Low K
                                     QW
                                Chemcial
                                Chemical
                        class
                        reactivity
                                  40000
                                  0.85
     ppm
                              Adsorption in Soils
Adsorption Parameters

  K       N       Kor
 0.17
 0.20
 0.62
 0.88
 3.47
         0.93
         0.95
         0.86
         0.85
         0.89
33
18,
23
23
18.9
                                            Soil Properties
Percent (%)
PH
7.30
6.83
5.00
7.30
6.98
CEC
5.71
6.10
21.02
37.84
77.34
OC
0.51
1.07
2.64
3.80
18.36
Sand
77
83
37
21
42
Silt
15
9
42
55
39
Clay
8
8
21
24
19
                             Degradation in Soils
  Degradation Parameters
                                              Soil Properties
tl/2

0
0
0
0
<0
Ks n
.00273
.0087
.0420
.0322
.0032
Mois-
Initial Temp, ture
cone. C 0

PH
5.
7.
7.
7.

4
8
5
5

CEC
0
1
0
0

OC
.58
.16
.15
.15
Percent (%)
Sand Silt


Clay

                           Volatilization in Soils
Volatilization Parameters

         KwKQ
                                 OC (%)
                                         	Soil  Properties
                                          MoistureBulkTemp.
                            0
Density    C
Porosity
                                       247

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Compound Name:   Aldrin [l,2,3,4,10,10-Hexachloro-l,4,4a,5,8,8a-hexachloro-l,4-
                endoexo-5, 8-dimethanonaphthalene]
Compound Properties:

M.W.           364.9
M.P.           104
B.P.
Sp. gr.
Vapor pressure 2.3lxl-~-> torr
                 (20C)
                                              Structure
           Water  solubility  0.025 ppm
           Log Kow           -0.14
           Chemical  class
           Chemical  reactivity
                              Adsorption in Soi1s
Adsorption Parameters


  K       N       K,
                   nr
        0.7783   253d
                       Soil  Properties
               CEC
                                  Percent (%)
          SandSTTt
Clay
                             Deqradation in Soils
  Degradation Parameters
                         Soil  Properties
tl/2
       0.0149
       0.0165
       0.0061
       0.0096
       0.0038
                Mois-
Initial   Temp,   ture
 cone.     C      0
                                                             Percent (%)
pH    CEC    QC   Sand' Silt  Clay
7.8         0.93
8.6         0.15
                           Volatilization in Soils
Volatilization Parameters
                           Soil Properties
                                          Moisture   Bulk     Temp.
                                 PC (%)      e      Density    C      Porosity
aThese are average values from three soils.
                                        248

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Compound Name: 2-Ammoanthracene

Compound Properties:
           Structure
M.W. 193.2 Water solubility
M.P. Log Kow
8. P. Chemical class
Sp. gr . Chemical reactivity
Vapor pressure
Adsorption in
Adsorption Parameters
1.3 yg/1
4.13
Soils
Soil Properties
Percent (%)
K N
321.6
329.2
304.1
259.5
79.0
103.7
145.1
191.9
283.0
458.7
531.9
502.1
875.2
688.7
Knr
26580
15904
13338
36039
52659
94276
30225
41248
42878
35287
28292
30069
36772
48537
pH

7.79
7.74
7.83
8.32
8.34a
4.54a
7.79
7.76
5.503
7.60
7.55
6.70
7.75
CEC
3.72
23.72
19.00
33.01
3.72
12.40
18.86
11.30
15.43
8.50
8.33
8.53
31.15
20.86
Degradation in
Degradation

Parameters



Initial Temp.
t!/? K,
n cone
C

Mois-
ture
0
OC
1.21
2.07
7.28
0.72
0.15
0.11
0.48
0.95
0.66
1.30
1.88
1.67
2.38
1.48
Soils
Soil


pH
Sand
67.5
3.0
33.6
0.2
82.4
7.1
2.1
15.6
34.6
0.0
50.2
26.1
17.3
1.6

Properties


CEC OC
Silt
13.9
41.8
35.4
31.2
10.7
75.6
34.4
48.7
25.8
71.4
42.7
52.7
13.6
55.4



Percent (
Sand Si
Clay
18.6
55.2
31.0
68.6
6.8
17.4
61.6
35.7
39.5
28.6
7.1
21.2
69.1
42.9



X)
It Clay
                           Volatilization in Soils
Volatilization Parameters
Soil Properties
                                          Moisture   Bulk     Temp.
                                 OC (%)       6     Density     C      Porosity
aSoils; all others are sediments.
                                        249

-------
Compound Name:  6-aminochrysene

Compound Properties:
                                                                   Structure
M.W.
M.P.
B.P.
Sp. gr
Vapor

243.2
210-211'C
pressure

Water solubility 0.155
Log Kow 4.99
Chemical class
Chemical reactivity
Adsorption in Soils
ug/i


Adsorption Parameters
K
                   nr
1688.8
               143427
               150519
               174232
               149817
               382185
               624022
               192553
               136025
               215835
                67070
               139149
                87363
               164844
               114108
                                            Soil Properties
PH
CEC
                                                       Percent  (%)
                                             OC
                                                      Sand
                                          Silt
               Clay
                             Degradation in Soils
  Degradation Parameters
                                              Soil Properties
                Mois-
Initial   Temp,   ture
 cone.     C      0
                                            pH
                                                  CEC
                                                             Percent  (%)
OC   Sand  Silt  Clay
                           Volatilization in Soils
Volatilization Parameters
                                 QC  (%)
                                         	Soil Properties
                                          Moisture   Bulk     Temp.
                                                    Density
                                                 Porosity
                                        250

-------
Compound Name:  Anthracene

Compound Properties:

M.W.           178.2          Water solubility 0.075 mg/1  (15C)
M.P.           216C          Log Kow          4.45
B.P.           342C          Chemical class
Sp. gr.                       Chemical reactivity
Vapor pressure 196xlQ-4 torr (20C)

                              Adsorption in Soils	
                                       Structure
Adsorption Parameters

  K       N       K,
                Soil Properties
                   or.
PH
CEC
                           Percent (%)
OC
Sand
Silt
Clay
                             Degradation in Soils
Degradation Parameters

tl/2
175
143
108
138
129
3.5
42
36
45
43
39
43

Volati

oir
0.004
0.005
0.006
0.005
0.005
0.198
0.017
0.019
0.015
0.016
0.018
0.016

1 ization
Initial
n cone.
3.4
13.7
10.3
11.4
40.0
36.4
25000
41
0.41
47
0.49
62
0.60
Vol
Parameters
Soil Properties
Mois-
Temp. ture Percent (%)
"C G pH CEC OC Sand Silt Clay
<15
15-25
15-25
15-25
15-25
15-25
>25






at il ization in Soils
Soil Properties
                                 OC (%)
              Moisture
                 9
                 Bulk
                Density
                 Temp.
                  C
                Porosity
                                        251

-------
Compound Name:   Anthracene-9-Carboxylic acid

Compound Properties:
M.W.
M.P.
B.P.
Sp. gr.
Vapor pressure
            222.2
                                                           Structure
             Water solubility  85 pg/1
             Log Kow           3.11
             Chemical  class
             Chemical  reactivity
                              Adsorption in Soils
Adsorption Parameters
  K
       N
 K,
   27
   49
   96
   47
   84
   82
                   nr
10.03
 2,
 1
13
 6
 5
 9
66
78
27
45
59
88
 7.50
 463
 265
 349
 760
1227
2564
2090
 280
 270
1021
 343
 335
 415
 507
                                         Soil Properties
pH
CEC
                                                       Percent (%)
ocr
Sand
STTt
Clay
                             Degradation in Soils
  Degradation Parameters
                                           Soil Properties
                                     Mois-
                     Initial  Temp,  ture
                      cone.    "C      6
                                         pH
                                 CEC
                                                          Percent  (%)
                             OC
                          Sand  Silt  Clay
                           Volatilization in Soils
Volatilization Parameters
                                             Soil Properties
                                          MoistureBulk
                                 OC  (%)       9      Density
                                                            Temp.
                                                             C
                                                     Porosity
                                         252

-------
Compound Name:  Atrazine [2-chloro-4-ethylamino-6-isopropylamino-l,3,5-
                triazine]
Compound Properties:
M.W.
M.P.
B.P.
Sp. gr.
215.7
173-175C
Vapor pressure 1.4xlO"6 mm Hg (30C)
Water solubility  70 mg/1 (20C
                  33 mg/1 (278C)
Log Kow           2.68
Chemical class
Chemical reactivity
                                                   Structure
                              Adsorption in Soils
Adsorption Parameters
Soil Properties

Percent (%)
K
6 .03
0.89
0.62
0.62
0.21
2.61
1.2
0.4
0.7
0.8
1.6
1.2
1.9
1.5
2.5
1.5
1.5
1.1
2.0
1.1
2.9
2.8
1.8
3.5
4.1
3.7
2.9
9.5
10.3
10.6
11.8
13.8
12.3
17.4
N Knr
0.73 155.8
1.04 98.9
0.79 110.7
0.93 124.0
1 80.8
0.85 174
1200
100
140
89
178
100
146
100
167
100
94
69
118
78
107
90
53
92
89
57
37
101
104
84
87
99
87
113
PH
7.3
5.6
5.6
7.4
6.5
6.8
7.0
6.6
6.2
4.9
5.7
5.9
6.1
5.8
6.7
6.2
5.8
6.9
6.4
6.7
6.6
6.5
6.9
6.5
5.7
7.6
7.2
6.8
5.3
7.1
7.1
6.9
6.5
6.5
CEC
54.7
6.8
5.2
35.8
5.1
20.0
25.4
10.2
10.6
11.0
9.2
12.4
14.0
11.0
30.1
13.9
10.3
20.2
21.5
22.3
24.8
25.9
29.2
26.9
27.4
25.7
42.0
44.6
51.3
37.6
11.2
50.4
61.3
82.1
OC Sand
3.87 18.4
0.90 65.8
0.56 93.8
0.50 56.7
0.26* 77
1.503 16
0.1
0.4
0.5
0.9
0.9
1.2
1.3
1.5
1.5
1.5
1.6
1.6
1.7
1.8
2.7
3.1
3.4
3.8
4.6
6.5
7.8
9.4
9.9
12.6
13.6
14.0
14.1
15.4
Silt Clay
45.3 38.3
19.5 14.7
3.0 3.2
16.4 22.9
18 5
68 16
42.8
8.2
15.8
13.9
20.3
28.5
10.3
17.9
27.8
33.5
21.0
22.0
35.2
37.1
61.6
63.4
31.9
25.9
30.2
28.1
33.8
20.1
29.5
28.4
8.1
17.6
51.2
28.7
^Reported as OM.
                                        253

-------
Compound Name:   Atrazine (continued)
Compound Properties:

M.W.            215.7         Water solubility  33 mg/1 (27'C)
M.P.            173-175C     Log Kow           2.68
B.P.                          Chemical class
Sp.  gr.                       Chemical reactivity
Vapor pressure 1.4xlO'6 mm Hg (30C)

                              Adsorption in Soils	
                                                                   Structure
Adsorption Parameters

  K       N
                  187
                  117
                  115
                  119
                  134
                  108
                   97
                                            So i1 Properties

pH
b. 5
5.9
6.8
6.9
6.8
5.6
6.7
6.9

CEC
84.3
92.3
94.2
83.1
106.7
126.9
131.1
123.1

OC
lb.8
18.6
18.9
20.0
22.9
23.6
25.9
27.1
Percent (%)
Sand Silt Clay
19.4
31.4
11.2
12.8
7.3
32.1
24.9
18.8
                             Degradation in Soils
  Degradation Parameters
                                              Soil Properties
*1Z2L  J<
       0.5l31
       0.0063
       0.0064
       0.0133
       0.0149
                Mois-
Initial   Temp,   ture
 cone.     C      0
                                            6.5
                                            6.5
                                            6.8
                                            6.4
                                                  CEC
                                                             Percent (%)
     OC
    CT5F
    1.16
                                                              Sand  Silt  Clay
                           Volatilization in Soils
Volatilization Parameters
                                 OC (%)
                                                Soil Properties
                                          Moisture
                                              G
"BuTF
Density
                                                               Temp.
                                                               C
                                                 Porosity
                                         254

-------
Compound Name:   Benefin [N-butyl-N-ethyl-a, a, crtrifluoro-2, 6-dinitro-N,
                N-dipropyl-p-toluidine]
Compound Properties:

M.W.           335.3
M.P.
B.P.
Sp. gr.
Vapor pressure
                                      Structure
Water solubility
Log Kow
Chemical class
Chemical reactivity
                              Adsorption in Soils
Adsorption Parameters
K N Knr
Soil Properties

pH CEC OC
Percent (%)
Sand Silt Clay
                             Degradation in Soils
Degradation Parameters
tl/2 Ks
1/ba
663
168a
543
Initial Temp.
n cone. C
30
15
30
Soil Properties
Mois-
ture
0 pH
7
6
6
Percent (%)
.6"
.6
.6
.6
CEC
~TT
11
19
19
74
.4
.4
.4
OC
o!g
1.2
1.2
Sand
3& 5"4
2b 64
8b 35
8b 35
Silt
20
45
45
Clay
14
20
20
                           Volatilization in Soils
Volatilization Parameters
                  Soil Properties
                                          MoistureBulkTemp.
                                 OC (_%)      e      Density    "C     Porosity
Reported in months.
Reported as OM.
                                        255

-------
Compound Name:  1,2-benzanthracene (benz(a)anthracine)

Compound Properties:
                                         Structure
M.W.           228.2          Water solubility
M.P.           162C          Log Kow
B.P.                          Chemical class
Sp. gr.                       Chemical reactivity
Vapor pressure 5.0x10-9 torr (20C)

	Adsorption in Soils
                       0.014 mg/1
                       5.61
Adsorption Parameters

  K       N       Knr
                 Soil Properties
pH
CEC
                            Percent (%)
                  OC
                                                      Sand
Silt
Clay
  Degradation in Soils
Degradation
"Hi" 0.816
134 0.005
41 0.017
142 0.005
41 0.017
154 0.005
Parameters
Initial Temp.
n cone. C
7
0.07
8.2
0.1
9.7
0.15
Soi
Mois-
ture
e PH
6.1
6.1
6.1
6.1
6.1
6.1
1 Properties
Percent (%)
CEC OC Sand Silt
0.75
0.75
0.75
0.75
0.75
0.75


Clay

Volatilization in Soils
Volatilization Parameters
KW ^w^D ^C (*)

Soi
Mo isture
0
1 Properties
Bulk
Density
Temp.
C
Porosity
             256

-------
Compound Name:  Benzene

Compound Properties:
M.W.
M.P.
B.P.
Sp. gr.
Vapor pressure
78.1
                                                    Structure
Water solubility
Log Kow
Chemical  class
Chemical  reactivity
                              Adsorption in Soils
1.8  g/1
2.13
Adsorption Parameters
Soil Properties
Percent (%)
K
2 .43
1.8*
30. 9a
4.43
0.35

N
0.89
0.94
1.08
0.99


Degradation




Kor pH CEC
92 5.6
100 7.8
4.2
6.6
31.4
Degradat
Parameters

Initial Temp.
17
29
80
80
14
ion in

Mois-
ture
OC
2.6
1.8
0
0
1.10
Soils
Soil


Sand
1
15


9

Propert


Silt
68
51


68

ies

Percent (
Clay
31
34
loot"
100C
21



%)
*U2_  -1
                      cone.     "C      9
                            PH
                    CEC
       OC
Sand  Silt  Cla\
                           Volatilization  in  Soils
Volatilization Parameters
                                Soil  Properties
                                          Moisture   Bulk      Temp.
                                 OC  (%)       Q      Density  _'C     Porosity
Reported in terms of ng to convert  to  g multiply by (10~3)
t>Al -Montmori llonite
cCa-Montmorillonite
                                       257

-------
Compound Name:  Benzo(b)fluoranthene

Compound Properties:

M.W.           252.3          Water solubility
M.P.           167            Log Kow
B.P.                          Chemical class
Sp.  gr.                        Chemical reactivity
Vapor pressure 5.0x10'7 torr (20C)

 	Adsorption in Soils
                      0.0012 mg/1
                      6.57
                                        Structure
Adsorption Parameters

  K       N       K
                Soil Properties
PH
CEC
                           Percent (%)
OC
Sand
Silt
Clay
                             Degradation in Soils
Degradation Parameters
Soil Properties
Mois-

^&-
98
85
123
73
130

Volati

0.010
0.007
0.008
0.006
0.010
0.006

1 izat ion
Initial Temp, ture
n cone. C 0
33
0.33
46
0.57
53
0.8
Vol atil izat ion
Parameters

pH
6.1
6.1
6.1
6.1
6.1
in Soi

Percent (%)
CEC OC Sand Silt Clay
O./b
0.75
0.75
0.75
0.75
0.75
Is
Soil Properties
                                          Moisture   BulK     Temp.
                                 OC (_%)       9     Density     C      Porosity
                                       258

-------
Compound Name:  Benzo(k)fluoranthene

Compound Properties:

M.W.           252.3          Water solubility
M.P.           217            Log Kow
B.P.                          Chemical class
Sp.  gr.                        Chemical reactivity
Vapor pressure 5.0x10-7 torr (20C)

 	Adsorption in Soils
                                                          Structure
                                        0.00055
                                        6.84
Adsorption Parameters
                                  Soil Properties
  K
N
                  lxnr
pH
CEC
                                                       Percent (%)
Sand
Silt
Clay
Degradation in
Degradation
TUO" 0.^07
89 0.008
87 0.008
94 0.007
100 0.007
87 0.008
Parameters
Initial
n cone.
1.7
0.1
2.6
0.15
2.7
0.17

Temp.
'C


Mo i s -
ture
0

Soils
Soi
pH
FTT
6.1
6.1
6.1
6.1
6.1

1 Properties
Percent (%)
CEC OC Sand Silt Clay
0.75
0.75
0.75
0.75
0.75
0.75
                           Volatilization in Soils
Volatilization Parameters
k" Y \(

OC (%)
Soil Properties
Moisture Bulk Temp.
G Density C

Porosity
                                        259

-------
Compound Name:  1,12-benzoperylene

Compound Properties:

               276.3
M.W.
M.P.
B.P.
Sp.  gr.
Vapor pressure
                                                                    Structure
Water solubility
Log Kow
Chemical  class
Chemical  reactivity
                              Adsorption in Soils
Adsorption Parameters Soil Properties
Percent (%)
K N Koc PH CEC OC
Sand Silt Clay
                             Degradation in Soils
  Degradation Parameters
                                              Soil Properties
                                     MOIS-
                     Initial   Temp,  ture
                      cone.     C      9
                                            pH
                    CEC
                                                             Percent (%)
OC   Sand  Silt  Clay
                           Volatilization in Soils
Volatilization Parameters
                                                Soil Properties
                                          MoistureBulk     Temp.
                                 OC (%)       9      Density    C     Porosity
                                       260

-------
Compound Name:  Benzo(a)pyrene  [3,4-benzopyrene]

Compound Properties:

M.W.           252.3          Water  solubility
M.P.           179            Log Kow
B.P.                          Chemical class
Sp. gr.    .                   Chemical reactivity
Vapor pressure 6.85x10" 7 torr (20C)

                              Adsorption  in Soils
                           Structure
          0.0038  mg/1
          6.04
Adsorption Parameters Soil Properties
K

N Koc pH CEC OC
Percent (%)
Sand Silt Clay
                             Degradation  in Soils
  Degradation Parameters

^g-
694
57
294
147
264
30
420
175
2
2
5
406
66
37

Ks n
0.014
0.001
0.012
0.002
0.005
0.003
0.023
0.002
0.004
0.347
0.347
0.139
0.002
0.011
0.019
Initial
cone.
0.048
0.01
3.4
9.5
12.3
7.6
18.5
17.0
32.6
1.0
0.515
1.00135
0.0094
0.545
28.5
    Soil Properties

Temp.
C
~25
>25
>25
Mois-
ture
0 pH
"57T
6.1
6.1
6.1
6.1
6.1







Percent (%)
CEC OC Sand Silt Clay
0.75
0.75
0.75
0.75
0.75
0.75






                          Volatilization in Soils
Volatilization Parameters
                                 OC (%)
      Soil
Moisture
Properties
"EUTS
          Density
Temp.
  C
                  Porosity
                                       261

-------
Compound Name:  Benzo(a)pyrene [3,4-benzopyrene] (continued)

Compound Properties:
                                                             Structure
M.W.           252.3          Water solubility
M.P.           179            Log KQW
B.P.                          Chemical class
Sp.  gr.                        Chemical reactivity
Vapor pressure 6.85x10-7 torr (20C)

 	Adsorption in Soils
                                            0.0038 mg/1
                                            6.04
Adsorption Parameters

  K       N       K,
                                     Soil Properties
                   or
                     PH
                             CEC
                                                Percent (%)
                         OC
                       Sand
       Silt
Clay
                             Degradation in Soils
  Degradation Parameters
tl/2
  39
   7
   5
   3
   4
   6
  92
  79
 100
  83
  92
 120
0
0.018
0.099
0.139
0.231
 .173
 ,116
0.008
0.009
0.007
0.008
0.008
0.006
0.
0.
              Initial
              cone.

              29.2
             910.0
 19.5
 19.5
 19.5
130.6
130.6
 36
  0.36
 55
  0.41
 69
                                       Soil Properties
                       Temp.
                       'C
>25
>25
>25
>25
>25
>25
                 Mois-
                 ture
                   0
                                    6.1
                                    6.1
                                    6.1
                                    6.1
                                    6.1
                  CEC
                          Volatilization in Soils
                        0.75
                        0.75
                        0.75
                        0.75
                        0.75
                                                             Percent  (%)
OC   Sand  Silt  Clay
Volatilization Parameters
                                         Soil Properties
                                          Moisture   Bulk     Temp.
                                 OC (%)       9     Density     C      Porosity
                                        262

-------
Compound Name:  Bromoform

Compound Properties:

M.W.           252.8
M.P.             8.3C
B.P.
Sp. gr.
Vapor pressure 5.6 mm (25C)
                                              Structure
           Water solubility  3190 mg/1 30C
           Log Kow
           Chemical class
           Chemical reactivity
                              Adsorption in Soils
Adsorption Parameters

  K       N       KQC
                       Soil Properties
       PH
CEC
                                  Percent (%)
OC
Sand
 Silt
Clay
                             Degradation in Soils
  Degradation Parameters
tl/2
                Mois-
Initial   Temp,   ture
 cone.     C      0
                         Soil  Properties
        pH
     CEC
                                                             Percent (%)
   OC
Sand  Silt  Cla\
                           Volatilization in Soils
Volatilization Parameters
                                 QC (%)
            Soil  Properties
      MoistureBulk
       Density
                                         Temp.
                                           C
                                  Porosity
                                       263

-------
Compound Name:   Bromomethane

Compound Properties:
                                               Structure
M.W. 94.95
M.P. -93C
B.P.
Sp. gr.
Vapor pressure

Adsorption Parameters

K N Kor
Water solubility 900 mg/1 (20C)
Log Kow 1.19
Chemical class
Chemical reactivity

Adsorption in Soils
Soil Properties
Percent (%)
pH CEC OC Sand Silt








Clay
                             Degradation in Soils
  Degradation Parameters
                         SoilProperties
tl/2
                Mo i s -
Initial   Temp,   ture
 cone.     C     Q
CEC
                                                             Percent (%)
OC   Sand  SiltClay
                           Volatilization in Soils
Volatilization Parameters
                           Soil  Properties
                                          Moisture   Bulk     Temp.
                                 OC (%)      0      Density    C     Porosity
                                       264

-------
Compound Name:
 Carbofuron [2,3-dihydro-2, 2-dimethylbenzofuron-7-yl
 methyl carbonate]
Compound Properties:
M.W.
M.P.
B.P.
Sp. gr.
Vapor pressure
219.2
                                                     Structure
Water solubi1ity
Log Kow
Chemical class
Chemical reactivity
                              Adsorption in Soils
Adsorption Parameters
          N
  14.7
  61.6
  51.9
  36
  39
  29
                   .5
                   .7
                   .6
         1.08
         0.98
         1.07
         0.88
  52.0

 210
  93
 324
  39
                             Soil Properties
Percent (%)
pH







6.1
6.6
6.8
7.0
CEC
1.7
7.5
34.4
24.8
27.7
55.5
72.4




OC
0.4
1.2
2.7
3.1
3.5
7.8
16.8
43.7
1.62
1.45
0.41
Sand







52
71
45
91.5
Silt







34
22
30
1.5
Clay







14
7
14
7
                             Degradation in Soils
  Degradation Parameters
                               Soil  Properties
       0.0/68
       0.0079
                     Initial
                      cone.
               Temp.
                C
     Mois-
     ture
       0
ElL

8.5
CEC
                 Percent  (%)
OC   Sand  Silt  Clay
                           Volatilization in Soils
Volatilization Parameters
                                 So i1  Properties
                                    "Bulk
                                          Moisture
                                 OC (%)       0     Dens it
                              Temp.
                               8C
                                                       Porosity
                                       265

-------
Compound Name:   Carbon tetrachloride (tetra chloromethane)

Compound Properties:
M.W.           153.8
M.P.           -23C
B.P.
Sp.  gr.
Vapor pressure  99 mm (20C)
    Water solubility  1160 mg/1 (25'C)
                       800 mg/1 (20C)
    Log Kow            2.73
    Chemical class
    Chemical reactivity

  Adsorption in Soils
                                        Structure
Adsorption Parameters
  <
                Soil Properties
PH
CEC
                                                       Percent (%)
OC
Sand
Silt
Clay
                             Degradation in Soils
  Degradation Parameters
                  Soil Properties
                                     Mois-
                     Initial  Temp,  ture
                      cone.    "C      0
                      CEC
                                 Percent (%)
                     OC
                 Sand  Silt  Cla\
                           Volatilization in Soils
Volatilization Parameters
                    Soil Properties
                                          Moisture   Bulk     Temp.
                                 OC (%)       0     Density    C     Porosity
                                       266

-------
Compound Name:  C6A-15646 [3-(3-chloro-4-methy1phenyl)-l,l-dimethylurea]
Compound Properties:

M.W.            212.7
M.P.
B.P.
Sp. gr.
Vapor pressure
                                                                  Structure
                               Water solubility   70  g/1
                               Log Kow
                               Chemical class
                               Chemical reactivity
                              Adsorption in Soils
Adsorption Parameters

  K       N       Koc
  .18
  .49
  .89
  .61
  .80
 4.61
 4.07
16.13
2,
2.
2,
3.
6,
0.79
0.81
0.88
0.81
0.90
0.89
0.86
0.74
150
146
203
148
249
246
333
346
                           pH
8
7.9
7.6
7.7
5.1
7.8
4.6
                                           Soil Properties
Texture

   S
   S
   S
   S
  S cl
   S
   S
   S
0.06
0.58
0.81
0.87
0.93
1.10
0.70
2.67
                                                      Percent (%)
                                             Sand
                                             STU
Clay

 9.8
15.0
13.0
 6.8
31.5
10.6
18.3
                                                                        4.5
                             Degradation in Soils
  Degradation Parameters
                                             Soil Properties
M/?
                    Initial
                     cone.
                              Temp.
                               C
                            Mois-
                            ture
                              G
                          PH
                      CEC
                                           Percent (%)
                       OCSand  SiltClay
                           Volatilization in Soils
Volatilization Parameters
                                               Soil Properties
                                          Moisture   Bulk     Temp.
                                 OC (%)      Q      Density    "C     Porosity
                                        267

-------
Compound Name:  Chlorobenzene

Compound Properties:
                                                Structure
M.W. 112.6
M.P. -45C
B.P. 131-132*C
Sp. gr.
Vapor pressure

Adsorption Parameters
K N Knr
0.91 - 82.7
Water solubility
Log Kow
Chemical class
Chemical
Adsorption

pH CEC
14
react iv
i n Soil
Soil

OC
1.10
490 mg/1 (20-25C)
2.84
ity
s
Properties
Percent (%)
Sand Silt
9 6.8





Clay
21
                             Degradation in Soils
  Degradation Parameters
tl/2
                         Soil  Properties
                Mois-
Initial   Temp,   ture
 cone.     "C      0
pH
CEC
                                                             Percent (%)
OC   Sand  Silt  Clay
                           Volatilization in Soils
Volatilization Parameters
                           Soil  Properties
                                          Moisture   Bulk     Temp.
                                 QC (%)       e      Density    "C     Porosity
                                       268

-------
Compound Name:  Chlorobromiiron [3-(4-bromo-3-ch1orophenyl 0-1-methoxy-l-
                methylurea]
Compound Properties:
M.W.
M.P.
B.P.
Sp. gr.
Vapor pressure
              293.5
                                                                   Structure
                                Water solubility  50 ug/1
                                Log Kow
                                Chemical class
                                Chemical reactivity
                              Adsorption in Soils
Adsorption Parameters
  K
6.
7.
   .98
   .98
 14.10
 19.10
 28.10
 39.80
128.00
 N

0.70
0.67
0.59
0.80
0.80
0.63
0.50
                 1533
                  684
                  561
                  772
                 1186
                 1502
                 3262
                 2758
                                          Soil Properties

pH
8.5
8.5
7.9
7.6
7.7
5.1
7.8
4.6

Texture
S
S
S
S
S cl
S
S
S

oc
0.06
0.58
0.81
0.87
0.93
1.10
0.70
2.67
Percent (%)
Sand Silt Clay
9.8
15.0
13.0
6.8
31.5
10.6
18.3
4.5
                             Degradation in Soils
Degradation Parameters

                   Initial
              n     cone.
                                              Soil Properties
                              Temp.
                               C
                                   Mois-
                                   ture
                                     G
                                                  CEC
                                                             Percent (%)
                                                OC   Sand  Silt  Clay
                           Volatilization in Soils
Volatilization Parameters
                                 OC (%)
                                              Soil  Properties
                                        Moisture^
                                           9
                                                    ~5UTF
                                                    Density
                                                     Temp.
                                                      C
                                                                    Porosity
                                       269

-------
Compound Name:  Chloroethane (gas)

Compound Properties:
M.W.      64.5
M.P.      -138.3C
B.P.
Sp.  gr.
Vapor pressure  457 mm (0"C)
                700 mm (10C)
               1000 mm (20C)
                1.7 atm (30C)
Water solubility  3330 mg/1 (0*C)
                   740 mg/1 (20"C)
Log Kow            1.43
Chemical class
Chemical reactivity
                              Adsorption in Soils
                                     Structure
Adsorption Parameters Soil Properties
Percent (%)
K N Knr pH CEC OC
Sand Silt Clay
                             Degradation in Soils
  Degradation Parameters
              Soil Properties
                                     Mois-
                     Initial  Temp,  ture
                      cone.    C      0
            pH
CEC
                             Percent (%)
OC   Sand  Silt  Clay
                           Volatilization in Soils
Volatilization Parameters
                Soil Properties
                                          Moisture   Bulk     Temp.
                                 OC (%)       Q     Density    "C     Porosity
                                        270

-------
Compound Name:  Chloroethene [Vinylchloride]  (gas)

Compound Properties:
                                     Structure
M.W.      62.5
M.P.      -153/-160C
B.P.
Sp. gr.
Vapor pressure  240 mm (-40C)
                580 mm (-20'C)
               2660 mm (25C)
Water solubility  1.1 mg/1 (25C)
Log Kow
Chemical class
Chemical reactivity
                              Adsorption in Soils
Adsorption Parameters

  K       N       IW
                                            Soil Properties
                            pH
    CEC
                                                       Percent  (%)
Sand
Silt
Clay
                             Degradation in Soils
  Degradation Parameters
              Soil  Properties
                                     Mois-
                     Initial  Temp,  ture
                      cone.    "C      9    pH
                  CEC
                             Percent (%)
   PC   Sand  Silt  Clay
                           Volatilization in Soils
Volatilization Parameters
                Soil  Properties
                                          Moisture   Bulk     Temp.
                                 PC (%)      6      Density    C     Porosity
                                       271

-------
Compound Name:  Chloroform [trichloromethane]

Compound Properties:
M.W.      119.4
M.P.      -64C
B.P.
Sp.  gr.
Vapor pressure  160 mm (20C)
                                Water solubility  8000 mg/1 (20C)
                                                  9300 mg/1 (25eC)
                                                 10000 mg/1 (158C)
                                Log Kow          1.96
                                Chemical class
                                Chemical reactivity
                                                                     Structure
                              Adsorption in Soils
Adsorption Parameters Soil Properties
Percent (%)
K N Knr pH CEC OC
Sand Silt Clay
                             Degradation in Soils
  Degradation Parameters
                                              Soil Properties
                                     Mois-
                     Initial  Temp,  ture
                      cone.    "C      0
                                            PH
CEC
                                                             Percent (%)
OC   Sand  Silt  Clay
                           Volatilization in Soils
Volatilization Parameters
                                                Soil Properties
                                          Moisture   Bulk     Temp.
                                 OC (%)       e     Density    "C     Porosity
                                       272

-------
Compound Name:  Chloromethane (gas)

Compound Properties:
M.W.       51
M.P.      -97.7C
B.P.
Sp.gr.
Vapor pressure 5.0 atm (20C)
               6.7 atm (30C)
Relative vapor
  density      1.8 (air = 1)
          Water solubility  4000 cm3/!
          Log Kow           0.91
          Chemical class
          Chemical reactivity
                              Adsorption in Soils
                                               Structure
Adsorption Parameters

  K       N       K,
                   DC,
      PH
CEC
                      Soil Properties
                                 Percent (%)
OC
Sand
Silt
Clay
                             Degradation in Soils
  Degradation Parameters	
                                     Mois-
                     Initial  Temp,  ture
M/2
cone.
   0
                        Soil Properties
                                                  CEC
                                       Percent  (%)
                                   OC   Sand  Silt  Cla\
                           Volatilization in Soils
Volatilization Parameters
                          Soil Properties
                                          Moisture   Bulk     Temp.
                                 QC (%)       0     Density     8C      Porosity
                                       273

-------
Compound Name:
Chlorpyrifos [0,0-diethyl  0-3,5,6-trichloro-2-pyridyl
phosphorothioate]
Compound Properties:

M.W.      350.6
M.P.
B.P.
Sp. gr.
Vapor pressure
                Water solubility  1.12
                Log Kow           5.11
                Chemical  class
                Chemical  reactivity
                              Adsorption in Soils
ppm
                                                     Structure
Adsorption Parameters
                            Soil Properties
Percent (%)
K

N
24.51 0.86
36.84
147.24
388.95
7095
103.3
101.7
13.4
0
0
0
1
0
0
0
.77
.91
.98
.09
.98
.99
.98
KOC
4806
3443
5577
10236
16236
6377
7014
3268
pH CEC

6.
5.
7.
6.
6.
6.
7.
3 5
83 6
00 21
30 37
1
6
8
0
.71
.10
.02
.84




Degradation
Degradat




ion


Parameters

In it


ial
ti/2 Kg n cone.
120
120




1
0.

1


Temp.
'C
20
20

Mo is
ture
9


OC
0.51
1.07
2.64
3.80
43.7
1.62
1.45
0.41
in So i 1 s
Soi
-

pH
6.2
6.2
Sand
77
83
37
21
52
71
56
91.5

1 Properties


CEC OC
20 1.74
20 1.74
Silt
15
9
42
55
34
22
30
1.5



Percent (
Sand Si
Clay
8
8
21
24
14
7
14
7



%)
It












Clay
51
-
-
51
Volatilization Parameters
           Volatilization in Soils __       	

                   	Soil  Properties
                                          MoistureBulKTemp.
                                 OC (%)       9     Density    C     Porosity
                                        274

-------
Compound Name:  Chrysene [1,2 benzophenanthrene]

Compound Properties:

M.W.      228.2 '                Water solubility  0.002 mg/1
M.P.      254C                 Log Kow           5.61
B.P.      448"C                 Chemical class
Sp. gr.                         Chemical reactivity
Vapor pressure 6.3xlQ-7 torr (20"C)

                              Adsorption in Soils       	
Adsorption Parameters

  K	N       Knr
                                            Soil Properties
                                                                     Structure
                            PH
CEC
                                                       Percent (%)
OC
Sand
Silt
Clay
                             Degradation in Soils
Degradation Parameters
tl/2
10.5
5.5
Ks n
0.067
0.126
Initial
cone.
4.4
500
5
Mo i s -
Temp, ture
C 0
15-25
15-25
Soil Properties
Percent (%)
pH CEC OC Sand Silt Clay

                           Volatilization in Soils
Volatilization Parameters
                                                Soil  Properties
                                          Moisture   Bulk     Temp.
                                 OC  (%)        0      Density    C     Porosity
                                       275

-------
Compound Name:  Cyanazine [2-[[4-Chloro-6-(ethylamino)-5-triazine-2-ylJamino]-
                2-methyl  propionitrile]
Compound Properties:

M.W.      206.2'
M.P.
B.P.
Sp. gr.
Vapor pressure
Water solubility
Log Kow
Chemical class
Chemical reactivity
                              Adsorption in Soils
                                     Structure
Adsorption Parameters
Soil Properties
Percent (%)
K
4.6
3.4
N
0.96
0.86
K0(-
368
453
pH CEC
6^7 8.'2
OC
1.25
0.75
Sand
11
90
Silt
63
8
Clay
26
5
                             Degradation in Soils
  Degradation Parameters
                                     Mois-
                     Initial  Temp,  ture
                      cone.    C      0
              Soil Properties
                  CEC
                             Percent (%)
OC   Sand  Silt  Clay
                           Volatilization in Soils
Volatilization Parameters
                Soil Properties
                                          MoistureBulk     Temp.
                                 OC (%)      0      Density    C     Porosity
                                       276

-------
Compound Name:  2,4-0 [2,4-Dichlorophenoxy acetic acid]

Compound Properties:
                                                              Structure
M.W.
M.P.
B.P.
Sp. gr.
Vapor pressure
  221.0
  135-138C
  160"C
                Water solubility  900 mg/1 (25C)
                Log KQW           2.81
                Chemical  class
                Chemical  reactivity
                              Adsorption in Soils
Adsorption Parameters
                  K,
                   oc
 1.30
 0.78
 0.47
 0.13
 0.31
 0.36
 0.09

 1.90
 0.21
1.00
0.98
1.01
1.00
0.97
1.01
0.79

0.90
0.86
 21.4
 10.8
 12.
  5.
 13.
 14.
  8.
109
 45.7
                                    Soil Properties
                    pH
                    CEC
                 "OT
                   Percent (%)
                           Silt
          Sand
5.9
7.7
6.5
7.7
          08
          20
          75
          41
          36
          48
          47,
          45,
          53,
7.5

5.9
7.7
19.0
31.1
1.03

1.74
0.46
 5.3
69.3
69.0
81.6

12
39
33.2
41.2
27.5
25.3
12.3
16.0
10.4

61
30
                             Degradation  in Soils
                  Clay
20.
13.
19.
69
18.
15.0
 8.0

27
31
  Degradation Parameters
                                      Soil Properties
tl/2
Ks n
0.1733
>0.0768
0.1386
0.1733
0.2731
Initial
cone.

                                     Mois-
                               Temp.  ture
                                C     0
                                     pH   CEC
                                                      Percent  (%)
                                10
                                         OC
                                        "2723

                                        1.91
                                        1.62
                                        1.86
                                   Sand   Silt   Clay
                           Volatilization  in Soils
Volatilization Parameters
  K,,
                         OC (%)
                          Moisture
                             0
                                        Soil Properties
                          Bulk
                         Density
                          Temp.
                           C
                          Porosity
                                        277

-------
Compound Name:  2,4-D amine

Compound Properties:

M.W.      236.1
M.P.      85-87C
B.P.
Sp.  gr.
Vapor pressure lx!0~y mm Hg
                 9 28C
                                                    Structure
               Water solubility 3xl06 mg/1  @ 20C
               Log Kow
               Chemical  class
               Chemical  reactivity
                              Adsorption in Soils
Adsorption Parameters
  K
 0.65
 0.76
  gr
119.4
 72.2
135.7
                           Soil  Properties
PH
5.6
9.6
CEC
54.7
6.8
5.6
Percent (%)
OC
3.87
0.90
0.56
Sand
18.4
65.8
93.8
Silt
45.3
19.5
3.0
Clay
38.3
14.7
3.2
                             Degradation in Soils
  Degradation Parameters
                             Soil Properties
tl/2   J
-------
Compound Name:  Dialifor

Compound Properties:

M.W.
M.P.
B.P.
Sp. gr.
Vapor pressure
           Water solubility
           Log  Kow
           Chemical  class
           Chemical  reactivity
                                                Structure
                              Adsorption in Soils
Adsorption Parameters

  K       N       K
                   nr
                       Soil  Properties
       PH
CEC
                                  Percent (%}
    Sand
TTTt
Clay'
                             Degradation in Soils
  Degradation Parameters
                         Soil  Properties
tl/2
140"
150
                Mois-
Initial   Temp,   ture
 cone.     "C      0
        PH
CEC
                                                             Percent  (%)
Sand  Silt  Clay
  1
  0.1
                           Volatilization in Soils
Volatilization Parameters
                           Soi1  Properties
                                          Moisture   Bulk     Temp.
                                 PC (%)       0     Density    C     Porosity
                                        279

-------
Compound Name:  1,2,5,6-dibenzanthracene [dibenz[a,b]anthrancene]

Compound Properties:
M.W.   278.4
M.P.   262"C
B.P.
Sp. gr.
Vapor pressure Ixl0~iu torr
                (20C)
    Water solubility  0.5 ug/1
    Log Kow           5.97
    Chemical  class
    Chemical  reactivity
                              Adsorption in Soils
                                         Structure
Adsorption Parameters

  K	N       KQC
                Soil Properties
pH
CEC
                           Percent (%)
OC
Sand
Silt
Clay
                             Degradation in Soils
Degradation Parameters
Soil Properties
Mois-

t]/2
21
18
130
183
99
141
119
190

Vol ati

I/
0.033
0.039
0.005
0.004
0.007
0.005
0.007
0.004

1 ization
Initial Temp, ture
n cone. C 0
97000 >25
25000 >25
57
57
93
4.54
147
3.46
Vol atil ization
Parameters

pH


6.1
6.1
6.1
6.1
6.1
6.1
in Soi

Percent (%)
CEC OC Sand Silt Clay


0.75
0.75
0.75
0.75
0.75
0.75
Is
Soil Properties
                                          Moisture   Bulk     Temp.
                                 OC (%)       9     Density     C      Porosity
                                        280

-------
Compound Name:  1,2,5,6-dibenzantnracene

Compound Properties:

       278.3
                                                                     Structure
M.W.
M.P.
B.P.
Sp.  gr.
Vapor pressure
Water solubility  249  g/1
Log Kow           6.50
Chemical  class
Chemical  reactivity
                              Adsorption in Soils
Adsorption Parameters Soil Properties

K N
20461
34929
18361
18882
1759
2506
14497
25302
20192
7345
55697
39809
19254
39840

Degradation


ti/? K,
Percent (%)
Knr pH CEC OC Sand Silt Clay

1690971
1687404
805292
2622453
1172847
2277875
3020262
2663317
3059425
565014
2962603
2383765
808991
2691870
Degradation in Soils
Parameters Soil Properties
Mo i s -
Initial Temp, ture Percent (%)
n cone. C 0 pH CEC OC Sand Silt Clay
                           Volatilization in Soils
Volatilization Parameters
                                                Soil Properties
                                          Moisture   Bulk
                                 OC (%)      y      Density
                                                              Temp.
                                                               C
                                      Porosity
                                       281

-------
Compound Name:  Dibenzothiophene

Compound Propert i es :
                                                              Structure
184.27
99-100C
M.W.
M.P.
B.P.
Sp. gr.
Vapor pressure
Water solubility  1.47
Log Kow           4.38
Chemical  class
Chemical  reactivity
                              Adsorption in Soils
   ppm
Adsorption Parameters
                                     Soil Properties

K
117.5
180.6
167.1
60.8
9.4
5.8
49.7
179.9
65.1
101.4
276.0
176.3
338.6
134.5

N
-
-
-
-
-
-
-
_
_
_
-
.
_
-

Kgr
9/11
8725
7329
8444
6267
5273
10354
18937
9864
7800
14681
10557
16328
9088

PH
6 .35
7.79
7.44
7.83
8.32
8.34
4.54
7.79
7.76
5.50
7.60
7.55
6.70
7.75

CEC
3.72
23.72
19.00
33.01
3.72
12.40
18.86
11.30
15.43
8.50
8.33
8.53
31.15
20.86
Degradation in
Degradation


*fr
24


U.U29
0.029
Parameters

In it


ial Temp
n cone. C
69
0.

57

Mois-
ture
0



OC
1.21
2.07
2.28
0.72
0.15
0.11
0.48
0.95
0.66
1.30
1.88
1.67
2.38
1.48
Soils
Soi


pH
S7T
6.1
Percent (%)
Sand Silt Clay
18.6
55.2
31.0
68.6
6.8
17.4
63.6
35.7
39.5
28.6
7.1
21.2
69.1
42.9

1 Properties

Percent (%)
CEC OC Sand Silt Clay
O./b
0.75
                           Volatilization  in Soils
Volatilization Parameters
                                         Soil Properties
                                 OC  (%)
                                   Moisture
                                       9
 Bulk
Density
                               Temp.
                                c
Porosity
                                        282

-------
Compound Name:  1,2-bibromo, 3-chloropropane

Compound Properties:

       236.3
M.W.
M.P.
B.P.
Sp.  gr.
Vapor pressure
Water solubility
Log Kow
Chemical  class
Chemical  reactivity
                              Adsorption in Soils
                                                                     Structure
Adsorption Parameters
K N Koc
Soil Properties
Percent (%)
pH CEC OC Sand Silt Clay
                             Degradation in Soils
  Degradation Parameters
                                              Soil  Properties
                                     Mois-
                     Initial  Temp,   ture
                      cone.     "C      0    pH
                                                  CEC
                                                             Percent (%)
                         OC   Sand  Silt  Clay
                           Volatilization in Soils
Volatilization Parameters
                                                Soil  Properties
                                          MoistureBulk
                                 OC (%)        9     Density
                                                              Temp.
                                                               C     Porosity
                                       283

-------
Compound Name:  Dibromomethane [methylene bromide]

Compound Properties:
M.W.   173.9
M.P.   -52.8C
B.P.
Sp. gr.
Vapor pressure 340 mm (20C)
    Water solubility  3218 mg/1 (20aC)
                      5033 mg/1 (30C)
    Low Kow
    Chemical  class
    Chemical  reactivity

  Adsorption  in Soils	
                                         Structure
Adsorption Parameters

  K	N       KQC
                Soil Properties
pH
CEC
                           Percent (%)
OC
Sand
Silt
Clay
                             Degradation in Soils
  Degradation Parameters
                  Soil Properties
                                     Mois-
                     Initial  Temp,  ture
                      cone.    C      Q
                pH
              CEC
                                 Percent (%)
                 Sand  STlt  Claj
                           Volatilization in Soils
Volatilization Parameters
                    Soil Properties
                                          Moisture    Bulk      Temp.
                                 QC  (%)       G     Density     C      Porosity
                                         284

-------
Compound Name:  Dicamba [3,6-dichloro-2-methoxybenzoic acid]

Compound Properties:

       221.0
M.W.
M.P.
B.P.
Sp.  gr.
Vapor pressure
                                                                     Structure
           Water solubility  4470 mg/1
           Low Kow           -1.69
           Chemical  class
           Chemical  reactivity
                              Adsorption in Soils
Adsorption Parameters
Soil Properties
Percent (%)
K N Knr
0.11 0.72
0.00
0.00
0.00
0.00
PH

6.5
7.7
7.8
7.5
CEC OF
6.08
3.75
2.41
2.36
1.03
Sand
47.5
53.3
5.3
69.3
81.6
Silt
33.2
27.5
25.3
12.3
10.4
Clay
20.3
19.2
69.5
18.5
8.0
                             Degradation in Soils
  Degradation Parameters
                                              Soil Properties
tl/2
        Ks
       0.2140
       0.2140
       0.0486
       0.0982
       0.0217
       0.0407
       0.0267
Initial
 cone.
Temp.
 C
                                     Mois-
                                     ture
                                       5%
                                      10%

                                      25%
                                      35%
                       7.5
                       7.5
                       5.2
                       7.7
                       7.7
                                                             Percent (%)
pH    CEC    PC   Sand  Silt  Clay
                          1.86
                          1.86
                          6.79
                          2.43
                          2.43
                                                        1.91
                                                        1.62
                                                        2.20
                           Volatilization in Soils
Volatilization Parameters
                                                Soil Properties
                                 QC (%)
                                          Mo isture
                                              0
                                Bulk
                               Density
                                Temp.
                                 C
                          Porosity
                                        285

-------
Compound Name:  Dicapthon [0-(2-chloro-4-nitropheny1)  0,0-dimethyl-
                phosphorothioate]

Compound Properties:
                                                Structure
M.W. 297.7
M.P. 53C
B.P.
Sp. gr.
Vapor pressure
Adsorption
K
Parameters
N Knr
Water solubility
Low Kow
Chemical class
Chemical react ivi
Adsorption in Soils
Soil

pH CEC OC
ty
Properties
Percent (%)
Sand Silt Clay
                             Degradation in Soils
  Degradation Parameters
                         Soil  Properties
 43
                Mois-
Initial   Temp,   ture
 cone.     C      e
  071
                                            pH
CEC
                                                             Percent (%)
OCSandSiltCla\
                           Volatilization in Soils
Volatilization Parameters
                           Soil Properties
                                          Moisture   Bulk     Temp.
                                 OC (%)       9      Density    C     Porosity
                                       286

-------
Compound Name:  1,2-dichlorobenzene

Compound Properties:

       147.0
M.W.
M.P.
B.P.   180.5C
Sp.  gr.
Vapor pressure
Water solubility  150 mg/1
Log Kow           3.38
Chemical class
Chemical reactivity
                              Adsorption in Soils
                                                                     Structure
Adsorption Parameters
Soil Properties
Percent (%)
K N Knr
3.54 - 321.6
PH

CEC
14
OC
1.10
Sand
9
Silt
68
Clay
21
                             Degradation in Soils
  Degradation Parameters
                                              Soil  Properties
                                     Mois-
                     Initial  Temp,  ture
                      cone.    C      0    pH
                                                  CEC
                                                             Percent (%)
                         OC   Sand  Silt  Clas
                           Volatilization in Soils
Volatilization Parameters
                                                Soil  Properties
                                          Moisture   Bulk     Temp.
                                 OC (%)      6      Density    C     Porosity
                                       287

-------
Compound Name:  1,3-dichlorobenzene

Compound Properties:

       147.0
M.W.
M.P.
B.P.   173C
Sp. gr.
Vapor pressure
Water solubility  134 mg/1
Log Kow           3.38
Chemical  class
Chemical  reactivity
                              Adsorption in Soils
                                                                     Structure
Adsorption Parameters
K N Knr pH CEC
3.23 - 293.3 14
Soil Properties
Percent (%)
OC
1.1
Sand
9
Silt
68
Clay
21
                             Degradation in Soils
  Degradation Parameters
                                              Soil Properties
                                     Mois-
                     Initial  Temp,  ture
                      cone.    C      0
                                                  CEC
                                                             Percent (%)
                         OC   Sand  Silt  Cla\
                           Volatilization in Soils
Volatilization Parameters
                                                So i1 Properties
                                          TToisture   Bulk     Temp.
                                 OC (%}       Q     Density    C     Porosity
                                        288

-------
Compound Name:   1,4-dichlorobenzene

Compound Properties:
M.W.   147.0
M.P.    53.5C
B.P.   174.1C
Sp. gr.
Vapor pressure
           Water solubility  137 mg/1
           Log Kow           3.39
           Chemical  class
           Chemical  reactivity
                              Adsorption in Soils
                                                Structure
Adsorption Parameters
Soi
1 Properties
Percent (%)
-j
K
.01
N Kn
273
r pH CEC
.8
14
OC
1.

1
Sand
9
Silt Cl
ay
68 21
                             Degradation in Soils
  Degradation Parameters
                         Soil  Properties
tl/2
Initial
 cone.
                              Temp.
Mois-
ture
  e
pH
CEC
                 Percent (%)
OC   Sand  Silt  Cla\
                           Volatilization in Soils
Volatilization Parameters
                           Soil  Properties
                                          Moisture   bulk     Temp.
                                 OC (%)       6     Density     C     Porosity
                                        >89

-------
Compound Name:   l,4-Dichloro-2-butene

Compound Properties:
M.W.
M.P.     3.5C
B.P.
Sp.  gr.
Vapor pressure
Water solubility
Low Kow
Chemical  class
Chemical  reactivity
                              Adsorption in Soils
                                     Structure
Adsorption Parameters Soil Properties
Percent (%)
K N Knr pH CEC OC
Sand Silt Clay
                             Degradation in Soils
  Degradation Parameters
              Soil Properties
                                     MblS-
                     Initial   Temp,  ture
                      cone.    C      0
            PH
CEC
                             Percent
OC   Sand  Silt  Clay
                           Volatilization in Soils
Volatilization Parameters
                Soil Properties
                                          MoistureBulkTemp.
                                 OC (%)      9      Density    C     Porosity
                                       290

-------
Compound Name:  Dichlorodifluoromethane (gas)

Compound Properties:
M.W.     120.9
M.P.     -111C
B.P.
Sp. gr.
Vapor pressure
                                     Structure
Water solubility  280 mg/1 (25C)
Low Kow           2.16
Chemical class
Chemical reactivity
                              Adsorption in Soils
Adsorption Parameters Soil Properties
K

N Koc pH CEC OC
Percent (%)
Sand Silt Clay
                             Degradation in Soils
  Degradation Parameters
MX?
              Soil  Properties
                                     Mois-
                     Initial   Temp,   ture
                      cone.     C      9
            PH
CEC
                             Percent
bandSTTt  CTaj
                           Volatilization  in Soils
Volatilization  Parameters
                Soil  Properties
                                          MoistureBulk
                                 OC  (%)       0      Density
                              Temp.
                               C
                    Porosity
                                       291

-------
Compound Name:   1-1-Dichloroethane
Compound Properties:
          99.0
          -97.4C
M.W.
M.P.
B.P.
Sp.  gr.
Vapor pressure
                 70 mm (0C)
                180 mm (20'C)
                234 mm (25'C)
                270 mm (30C)
Water solubility
Low Kow
Chemical  class
Chemical  reactivity
                             5500 mg/1
                             1.79
                              Adsorption in Soils
                                                                     Structure
                                                            ;20C)
Adsorption Parameters

  K       N       i>nr
                                            Soil Properties
PH
CEC
                                                       Percent (%)
                                             OC
                                                      Sand
                                          Silt
                                        Clay
                             Degradation in Soils
  Degradation Parameters
MX?
                                              Soil Properties
                Mois-
Initial   Temp,   ture
 cone.     C      0
                                            pH
                                                  CEC
                                                             Percent (%)
                         OC   Sand  S iIt  Clay
                           Volatilization in Soils
Volatilization Parameters
                                                Soil Properties
                                          Moisture   Bulk     Temp.
                                 OC (%)      9      Density     JC      Porosity
                                        292

-------
Compound Name:  1-2-Dichloroethane

Compound Properties:
          99
          -35.4C
M.W.
M.P.
B.P.
Sp.  gr.
Vapor pressure
                 40 mm (10'C)
                 61 mm (20C)
                105 mm (30C)
Water solubility  8690 mg/1 (20C;
                  9200 mg/1 (O'C)
Low Kow           1.48
Chemical class
Chemical reactivity
                              Adsorption in Soils
                                                                     Structure
Adsorption Parameters
K N Knr
Soil Properties

pH CEC OC
Percent (%)
Sand Silt Clay
                             Degradation in Soils
  Degradation Parameters
                                              Soil  Properties
                                     Mois-
                     Initial  Temp,  ture
                      cone.    C      9
                                            pH
                  CEC
                                                             Percent (%)
OCSand  Silt  Clay
                           Volatilization in Soils
Volatilization Parameters
                                 QC (%)
                                                Soil  Properties
                                          Moisture
                                             9
                    "SUIT
                    Density
     Temp.
      C
Porosity
                                       293

-------
Compound Name:   1,2 Dichloropropane

Compound Properties:
                       Structure
M.W. 113 Water solubility 2700 mg/1 (20C)
M.P. -100/-80C Low Kow
B.P. Chemical class
Sp. gr. Chemical reactivity
Vapor pressure 42 mm (20C)
50 mm (25'C)
66 mm (30C)
Adsorption in Soils
Adsorption Parameters Soil Properties
Percent (%)
K N Kor pH CEC OC
Sand Silt Clay
                             Degradation in Soils
  Degradation Parameters
Soil Properties
                                     Mois-
                     Initial   Temp,  ture
                      cone.     C      0    pH
    CEC
               Percent (%)
OC   Sand  Silt  Clay
                           Volatilization in Soils
Volatilization Parameters
  Soi1 Properties
                                          Moisture   Bulk     Temp.
                                 OC (%)       G     Density    "C     Porosity
                                        294

-------
Compound Name:   1,3 Dichloropropane

Compound Properties:

          113
M.W.
M.P.
B.P.
Sp. gr.
Vapor pressure
Water solubility
Low Kow           2.00
Chemical class
Chemical reactivity
                              Adsorption in Soils
                                                                     Structure
Adsorption Parameters
K N Knr
Soil Properties

pH CEC OC
Percent (%)
Sand Silt Clay
                             Degradation in Soils
  Degradation Parameters
                                     Mois-
                     Initial  Temp,  ture
                      cone.    C      0
                                              Soil Properties
                                            PH
                  CEC
                                                             Percent (%)
bandSiltCTa\
                           Volatilization in Soils
Volatilization Parameters
                                                Soil Properties
                                          Moisture   Bulk     Temp.
                                 OC (%)       e     Density    C     Porosity
                                        295

-------
Compound Name:  Dieldrin [1,2,3,4,10,10-hexachloro-b, 7-epoxy-l,4,4a,5,6,7,3,
                8a-ortanydro-exo-l,4-endo-5,8-dimethanonaphthalene]
Compound Properties:

M.W.      380.9
M.P.      176-177'C
B.P.
Sp. gr.
Vapor pressure 1.78x10'' torr
                 ' 25*C
                                                 Structure
           Water solubility
           Low Kow           2.00
           Chemical class
           Chemical reactivity
                              Adsorption in Soils
Adsorption Parameters
Soil Properties


Percent (%)
K
39
147
265
198
260
297
1507
13937
117
66
17.8
N Koc
9750
12250
9815
6387
7429
3960
8970
1.08 31892
0.91 7222
0.89 4552
0.88 4341
pH







6.1
6.6
6.8
7.0
CEC
1.7
7.5
34.4
24.8
27.7
55.5
72.4




Degradation
OC Sand
0.4
1.2
2.7
3.1
3.5
7.5
16.8
43.7 52
1.62 71
1.45 56
0.41 91.5
in So i 1 s
Silt







34
22
30
1.5

Clay







14
7
14
7

  Degradation Parameters
                         Soil Properties
tl/?
       0.0002
       0.0001
                Mo i s -
Initial  Temp,  ture
 cone.    *C      0    pH    CEC
	778-  	
                       7.8

      Volatilization in Soils
                                                             Percent (%)
 OC   Sand  Silt  Clay
T573S        ~~
0.29
Volatilization Parameters
                           Soil Properties
                                          Moisture   Bulk     Temp.
                                 OC (%}      e      Density    "C     Porosity
                                        296

-------
Compound Name:   7,12-dimethylbenz(a)anthracene

Compound Properties:
                                                           Structure
M.W.
M.P.
B.P.
Sp. gr.
Vapor pressure
256.3
122-123C
Water solubility  24.4 yg/1
Low Kow           5.98
Chemical class
Chemical reactivity
                              Adsorption in Soils
Adsorption Parameters Soil Properties

K N
2371
2646
5210
1346
611
1028
562
3742
1895
1617
5576
2679
6777
3740

Degradation


tl/2 K5
Percent (%)
Kor pH CEC OC Sand Silt Clay
195998
127812
228499
186986
407496
934225
117161
393907
287196
124347
296580
160391
284743
252735
Degradation in Soils
Parameters Soil Properties
Mois-
Initial Temp, ture Percent (%)
n cone. "C 0 pH CEC OC Sand Silt Clay
                           Volatilization in Soils
Volatilization Parameters
                                      Soil Properties
                                          MoistureBulk
                                 _OC (%)       Q     Density
                                                    Temp.
                                                            Porosity
                                        297

-------
Compound Name:  2,6-dinitro-N(3-pentyl )-a,ct,ct-trif"luoro-p-toluidine

Compound Properties:                                                  Structure

          391.4
M.W.
M.P.
B.P.
Sp. gr.
Vapor pressure
Water solubility
Low Kow
Chemical class
Chemical reactivity
                              Adsorption in Soils
Adsorption Parameters Soil Properties
K

N Knr pH CEC OC
Percent (%)
Sand Silt Clay
                             Degradation in Soils
Degradation Parameters


ti/o Ks
168"
603
1083
423

Volatil ization
Mo i s -
Initial Temp, ture
n cone. C 0
15
30
15
30
Volati 1 ization
Parameters
Soil Properties







Percent (%)
pH
7.6
7.6
6.6
6.6
in Soi

CEC

11.
19.
19.
is
Soil
OC Sand
4
4
4
4

0.93U
0.93b
1.28b
1.28b

64
64
35
35

Silt
20
20
45
45

Clay
14
14
20
20

Properties
Reported in months.
bReported as OM.
                                          Moisture    Bulk      Temp.
                                 QC  (%)       e      Density    C     Porosity
                                        298

-------
Compound Name:  Oiuron [3-(3,4-dichlorophenyl)-l, 1-dimethylurea]

Compound Properties:
                                     Structure
M.W. 233.1
M.P. 158-159C
B.P.
Sp. gr.
Vapor pressure

Adsorption Parameters

K N Koc
14.3 0.77 1144
6.5 0.74 867
Water solubility
Low Kow
Chemical
Chemical

Adsorption


pH CEC
6.7 2U .
6.7 8.2

class
react ivi

in Soils
Soil

OC
7 1.25^
0.75a
42 (25'C)


ty


Properties
Percent (%)
Sand Silt
11 63
90 5








Clay
26
5
                             Degradation in Soils
  Degradation Parameters
             So i1 Properties
       0.0064
       0.0072
                                     Mois-
                     Initial  Temp,  ture
                      cone.    C      0
           pH
           O'
           6.4
CEC
                            Percent  (%)
OC   Sand  Silt  Cla\
                           Volatilization in Soils
Volatilization Parameters
	Soil Properties	
         MoistureBulkTemp.
OC (%)      0      Density    "C     Porosity
                                       299

-------
Compound Name:   Ethyl benzene

Compound Properties:
Adsorption Parameters

  K       N       K,
TT
                   nr
                  165
                            pH
CEC
14
                                            Soil Properties
            OC
            1.10
                                                       Percent
                                                Structure
M.W. 106.2
M.P. -94.97C
B.P. 136*C
Sp. gr.
Vapor pressure 7 mm
12 mm





(20'C)
(30C)

Water solubility 140 mg/1
152 mg/1
206 mg/1
Low Kow 3.15
Chemical class
Chemical reactivity
Adsorption in Soils
(15C)
(20C)
(30C)




                                 Sand
      Silt
       68
Clay
 21
                             Degradation in Soils
  Degradation Parameters
                         Soil  Properties
tl/2
Initial
 cone.
                              Temp.
                                     Mois-
                                     ture
                                       0
        pH
                 CEC
                         Percent (%)
OC   Sand  Silt
                           Volatilization in Soils
Volatilization Parameters
                           Soil  Properties
OC (%)
      Moisture
          G
                                                     Bulk
                                                    Density
                                         Temp.
                                          "C
                                                                      Porosity
                                        300

-------
Compound Name:  Fluometuron [1,1-Dimethyl-3- , , -trifluoro-m-tolyl)urea]

Compound Properties:                                                 Structure

          232.2
M.W.
M.P.
B.P.
Sp. gr.
Vapor pressure
 0.4
         0.98    40.4
  Water solubility  79.4 mg/1
  Low Kow           3.44
  Chemical class
  Chemical reactivity
                              Adsorption in Soils
Adsorption Parameters
Soil Properties
Percent (%)
K
0.90 '
0.80
N
_a
KOC
120
107
pH CEC OC
/.I U./b
7.1 0.75
Sand
25
25
Silt
43
43
Clay
32
32
6.6
9.2
0.99
46
37.6
16.4
                             Degradation in Soils
  Degradation Parameters
                                              Soil Properties
                                     MoTs-
                     Initial  Temp,  ture
                      cone.    C      0    pH
                                                  CEC
                                                             Percent  (%)
                           OC   Sand  Silt  Cla\
                           Volatilization in Soils
Volatilization Parameters



aN is assumed to be one.
                                                Soil Properties
                                          Moisture   Bulk     Temp.
                                 OC:_(%_)       e     Density    "C     Porosity
                                        301

-------
Compound Name:  Fluoranthene

Compound Properties:

M.W.      202.2
M.P.      Ill
B.P.
Sp. gr.
Vapor pressure 6.0x10- (20"C)
Water solubility  0.26 mg/1
Low Kow           5.33
Chemical  class
Chemical  reactivity
                              Adsorption In Soils
                                     Structure
Adsorption Parameters

  K       N       K
            Soil Properties
                       Percent (%}
                   nr
    CEC
Sand
Silt
Clay
                             Degradation in Soils
  Degradation Parameters
              Soil Properties
tl/2
44
182
105
143
109
175
133
Kc; n
0.016
0.004
0.007
0.005
0.006
0.004
0.005
Initial
cone.
3.9
18.8
23.0
16.5
20.9
44.5
72.8
Mois-
Temp. ture Percent (%)
C 0 pH CEC OC Sand Silt Clay
15-25
15-25
15-25
15-25
15-25
15-25
                           Volatilization in Soils
Volatilization Parameters
                Soil Properties
                                          MoistureSulkTemp.
                                 OC (%)       9      Density    C     Porosity
                                        302

-------
Compound Name:   Fonofos [0-Ethyl  S-phenyl ethylphosphonodithioate]

Compound Properties:                                                 Structure

          230.3
M.W.
M.P.
B.P.
Sp. gr.
Vapor pressure
Water solubility
Low Kow
Chemical class
Chemical reactivity
                              Adsorption in Soils
Adsorption Parameters Soil Properties
Percent (%)
K N Knr pH CEC OC
Sand Silt Clay
                             Degradation in Soils
  Degradation Parameters
  46
                                              Soil Properties
                                     Mois-
                     Initial  Temp,  ture
                      cone.     C      0
                                                  CEC
                                            8.2
                                                             Percent (%)
                         OC   Sand  Silt  Clay
                        ITS'  ~ZTT  ~5D~  ~3TT
                         2.0   30    20    50
                           Volatilization in Soils
Volatilization Parameters
                                          Moisture
                                 QC (%)       9      Density
                                                SoJJ Properties
                                                     BulkTemp.
                                                               C
                                      Porosity
                                       303

-------
Compound Name:  HCB [Hexachlorobenzene]

Compound Properties:
M.W.
M.P.
B.P.
Sp. gr.
Vapor pressure
 248.8
 230 C
 323-326C
                                                            Structure
               Water solubility
               Low Kow           4.13
               Chemical  class
               Chemical  reactivity
                              Adsorption in Soils
Adsorption Parameters
  K
 4193
  276
  136
 N
0.99
0.93

 5835
11525
                                   Soil Properties
Percent (%)
PH
?!l
4.5
CEC
72.4
18.1
13.1
OC
16.81
4.73
1.18
Sand
15. 7
6.1
1.1
Silt
50.8
61.4
64.3
Clay
33.5
32.5
34.6
                             Degradation in Soils
  Degradation Parameters
                                     Soil Properties
        Ks
                            MoTs-
            Initial  Temp,  ture
             cone.    *C      0
                                                             Percent (%)
                           PH
CEC
OC   Sand  Silt  Clay
                           Volatilization in Soils
Volatilization Parameters
                                       Soil Properties
                                          Moisture   Bulk
                                 OC (%)       9     Density
                                                      c
                                                     Porosity
                                       304

-------
Compound Name:   HCH [Hexachlorocyclohexane]
Compound Properties:
Structure
M.W. 290.8
M.P. 157-158'C (a)
309C (B)
112. 5C (Y)
B.P.
Sp. gr.
Vapor pressure
2.15x10-5 torr (a)
2.0x10-7 torr (8)
0.14 mm Hg (y)
Water solubility 1
0.
Low Kow 4
O i
3,
Chemical class
Chemical reactivity
(40C)
Adsorption in Soils
Adsorption Parameters
.63 ppm @ 25C (a.)
,70 ppm 9 25C (g)
.14 (Lindane)
,81 (a)
.81 (6)
Soil Properties
Percent (%)
K
"28 . 18
52.48
70.79
501.20
5.13
39.81
79.43
158.50
8.91
25.12
31.62
446.70
295
7.91
45.1
665
13.1
10.2
6.9
N
1.60
1.26
0.94
1.16
0.82
1.20
0.80
0.80
0.90
0.80
0.80
1.10
0.92
0.80
O.S4
0.98
0.96
0.97
0.99
Kqc
640b
3143
2212
3510
1166
2384
2482
1110
2025
1504
988
3128
1635
2274
1313
1522
809
703
1679
pH
b.ZU
6.30
5.20
3.30
6.20
6.30
5.20
3.30
6.20
6.30
5.20
3.30



6.1
6.6
6.8
7.0
CEC
ia.o
42.8
19.2
28.9
18.6
42.8
19.2
28.9
18.6
42.8
19.2
28.9
18
0.35
3.5




OC
0.44
1.67
3.20
14.28
0.44
1.67
3.20
14.28
0.44
1.67
3.20
14.28



43.7
1.62
1.45
91.5
Sand
/y.b
69.6
45.6
63.6
79.6
69.6
45.6
63.6
79.6
69.6
45.6
63.6



52
71
56
91.5
Silt
4.8
6-8
7.8
6.8
4.8
6.8
7.8
6.8
4.8
6.8
7.8
6.8



34
22
30
1.5
Clay
ib.b
23-6
45.6
29.6
15.6
23.6
45.6
29.6
15.6
23.6
45.6
29.6



14
7
14
7
                                       305

-------
Compound Name:  HCH [Hexachlorocyclohexane] (Continued)
                             Degradation in Soils
  Degradation Parameters
Soil  Properties


tl/2










Mo i s -
Initial Temp, ture Percent (%)
Ks n cone. "C 0 pH CEC OC Sand Silt Clay
U.UU22 /.8 U.bb
0.0026 7.8 0.29
0.0011
0.0014
0.0048
0.0147
0.0264
0.0074
0.0263
0.0264
0.0139
                           Volatilization in Soils
Volatilization Parameters
  Soil Properties
                                          Moisture   Bulk
                                 OC (%)      9      Density
                Temp.
                 C
Porosity
                                        306

-------
Compound Name:   Hexachlorocyclopentadiene

Compound Properties:
                                                            Structure
M.W.
M.P.
B.P.
Sp. gr.
272.8
9/10'C


Vapor pressure 0.08 mm (25


Adsorpt

K
1 mm (78-79

ion Parameters

Nv
OC
Water solubility


Low Kow
*C) Chemical class
*C) Chemical reactivi
Adsorption in Soils
Soil

pH CEC OC
0.8 ppm
1.8 ppm
2.0 ppm


ty

Properties
Percent (%}
Sand Silt Clay
                             Degradation in Soils
  Degradation Parameters
                                     Soil Properties
        Ks
                            Mois-
            Initial   Temp,   ture
             cone.     C      0
                 CEC
                                                             Percent (%)
OC   Sand  Silt  Clay
                           Volatilization in Soils
Volatilization Parameters
                                       Soi1  Properties
  KW
KwKD
         Moisture   Bulk
CC (%)      S      Density
                                                              Temp.
             Porosity
                                        307

-------
Compound Name:  Hexachloroethane

Compound Properties:                                                 Structure

M.W.      236.76                Water solubility  50 mg/1 (22C)
M.P.      187C                 Low Kow
B.P.                            Chemical class
Sp. gr.                         Chemical reactivity
Vapor pressure  0.4 mm (20C)
                0.8 mm (30*C)

	Adsorption in Soils	

Adsorption Parameters     	Soil Properties	
                                                       Percent  (%7
  K	    N       KQC       pH      CEC      OC       Sand     Silt     Clay
                             Degradation in Soils
  Degradation Parameters      	Soil Properties	
                                     Mois-
                     Initial  Temp,  ture               	Percent  (%)	
        Ks      n     cone.    C      9    pH    CEC    OC   Sand  Silt   Cla}
                           Volatilization  in Soils
Volatilization Parameters        	Soil Properties	
                                          Moisture   Bulk      Temp.
                                 OC  (%)       G     Density     C      Porosity
                                        308

-------
Compound Name:   Idomethane

Compound Properties:

M.W.      142
M.P.     -66.1  C
8.P.
Sp. gr.
Vapor pressure   400 mm (25C)
                                                Structure
           Water solubility   14 g/1  (20C)
           Low Kow           1.69
           Chemical  class
           Chemical  reactivity
                              Adsorption in Soils
Adsorption Parameters

  K       N       Koc
                       Soil  Properties
       PH
CEC
                                  Percent  (%)
OC
Sand
Silt
Clay
                             Degradation in Soils
  Degradation Parameters
                         Soil  Properties
H/2
                Mois-
Initial   Temp,   ture
 cone.     C      0
        pH
     CEC
                                                             Percent (%)
   OC   Sand  Silt  Cla\
                           Volatilization in Soils
Volatilization Parameters
                                 OC (%)
                           Soil  Properties
                     Moisture
                        0
                "BuTF
                Density
                 Temp.
                  C
                Porosity
                                       309

-------
Compound Name:  Indeno(l,2,3-Cd)-pyrene

Compound Properties:
M.W.      289.3
M.P.      163
6.P.
Sp. gr.
Vapor pressure  1.0x10-10
                  torr (20C)
    Water solubility  0.062 mg/1
    Low Kow           7.66
    Chemical  class
    Chemical  reactivity
                              Adsorption in Soils
                                         Structure
Adsorption Parameters

_J<	N       Koc
pH
CEC
                Soil Properties
                           Percent (17
OC
Sand
Silt
Clay
                             Degradation in Soils
  Degradation Parameters
                                     Mois-
                     Initial  Temp,  ture
                      cone.    C      Q
                  Soil Properties
                pH
                         Percent (%)	
              CEC    OC   Sand  Silt  Clay
                           Volatilization in Soils
Volatilization Parameters
         KwKD
                    Soil Properties
              Moisture   Bulk     Temp.
     OC (%)       e     Density     C     Porosity
                                        110

-------
Compound Name:  Linuron[3-(3-4-dichlorophenyl)-l-methoxy-l-methylurea]

Compound Properties:                                                  Structure

          249.1
M.W.
M.P.
B.P.
Sp. gr.
Vapor pressure
               Water solubility  75 ug/1
               Low Kow
               Chemical  class
               Chemical  reactivity
                              Adsorption in Soils
Adsorption Parameters
  K
   30
   80
   90
   50
   93
18.20
12.80
23.10
         J_

        0.84
        0.85
        0.79
        0.73
        0.94
        0.82
        0.77
        0.86
 Koc
1916
 470
 345
 655
 492
 913
1049
 497
Soil Properties

PH
8.5
8.5
7.9
7.6
7.7
5.1
7.8
4.6

Texture
S
S
S
S
S cl
S
S
S
Percent (%)
OC Sand Silt
0.06
0.58
0.81
0.87
0.93
1.10
0.70
2.67

Clay
4.8
15.0
13.0
6.8
31.5
10.5
18.3
4.5
                             Degradation in Soi 1 s
  Degradation Parameters
                                              Soil Properties
                                     M01S-
                     Initial  Temp,  ture
                      cone.    C      e
                                            PH
       0.0047
                                 CEC
                                                             Percent (%)
OC   Sand  Silt  Cla\
                           Volatilization in Soils
Volatilization Parameters
                                                Soil  Properties
                                         Moisture
                                 OC (%)
                                             0
                                   "BUTF
                                   Density
     Temp.
      C
Porosity
                                       311

-------
Compound Name:  Malathion [0,0-dimethyl  S-(l,2-di)(ethoxycarbonyl)ethy)-
                phosphorodithioate]
Compound Properties:
       Structure
M.W. 330.4
M.P. 2.9C
B.P. 156-157C
Sp. gr.
Vapor pressure
Adsorption
K 1
Parameters
1 Knr
Water solubility
Low Kow
Chemical class
Chemical react ivi
Adsorption in Soils
Soil

pH Texture OC
145 mg/1
ty
Properties
Percent (%)
Sand Silt



Clay
                             Degradation in Soils
Degradation Parameters
Soil Properties
Mois-

tl/2







Volati
Initial Temp, ture
KS n cone. C 0
2.9173
2.4618
1.2681
0.4152
1.9832
1.9026
Volati 1 izat ion
1 izat ion Parameters

pH
7.2
6.4
3.8
5.3
7.4
7.2
in Soi

Percent (%)
CEC OC Sand Silt Clay



0.64
1.80
2.73
Is
Soil Properties
                                          Moisture   Bulk
                                 QC (%)       0     Density
Temp.
 c
Porosity
                                        312

-------
Compound Name:  MCPA [4-chloro-2-methy1phenoxyacitic acidjarbonyl)ethy)-
                phosphorodithioate]
Compound Properties:
                           Structure
M.W. 200.6
M.P. 120"C
8. P.
Sp. gr.
Vapor pressure
Adsorption Parameters
K N Kor
Water solubility 890 mg/1
Low Kow -1.41
Chemical class
Chemical reactivity
Adsorption in Soils
Soil Properties
Percent (%)
pH Texture OC Sand Silt Clay
                             Degradation in Soils
  Degradation Parameters
    Soil Properties
                                     Mois-
                     Initial   Temp,   ture
                      cone.     'C      0    pH
                              ~
        CEC
                   Percent (%)
     OC   Sand  Silt  Clay
          3072  3275  TO"
                           Volatilization  in  Soils
Volatilization  Parameters
      Soil Properties
Moisture
                                 QC  (%)
"EuTF
Density
Temp.
 C
                            Porosity
                                       313

-------
Compound Name:  Methoxychlor [l,l,l-Trichloro-2, 2-bis(p-methoxypheny1)-
                ethane]
Compound Properties:

M.W.     345.65
M.P.      89C
B.P.
Sp. gr.
Vapor pressure
                                                                      Structure
                                Water solubility  0.12 mg/1
                                Low Kow           4.30
                                Chemical class
                                Chemical reactivity
                              Adsorption in Soils
Adsorption Parameters
                                            Soil Properties
                                                       Percent  (%)
 J<_

  53
2600
1800
1400
1100
   8.3
2200
1700
2300
2400
  95
2500
2000
2100
          N
                  lac_
                 41000
                 80000
                 91000
                100000
                 92000
                  9700
                 80000
                 73000
                 80000
                 73000
                 17000
                 86000
                100000
                 93000
                            pH
Texture
                OC
               0.13
               3.27
               1.98
               1.34
               1.20
               0.086
               2.78
               2.34
               2.84
               3.29
               0.57
               2.92
               1.92
               1.99

Degradation in Soils
Sand
Silt
Clay
  Degradation Parameters
                                               Soil  Properties
Initial Temp.
ti/2 KS n cone. "C
0.0046
0.0033
Mois-
ture
9 pH CEC
4.8
6.5
Percent (%)
OC Sand
0.58
1.16
Silt Clay

                            Volatilization  in  Soils
Volatilization Parameters
                                                 Soil  Properties
                                  OC  (%)
                                           Moisture
                                              0
                    Bulk
                   Density
        Temp.
          c
       Porosity
                                         314

-------
Compound Name:   3-Methylcholanthrene

Compound Properties:
                                    Structure
M.W.
M.P.
8. P.
Sp. gr.
Vapor pressure

268.3 Water solubility 3.23 pg/1
179-180'C Low Kow 6.42
280C Chemical class
Chemical reactivity

Adsorption in Soils
Adsorption Parameters Soil Properties

K N
15140
30085
8273
15820
2257
2694
30627
23080
20642
16231
24506
20972
17127
37364

Degradation


H/2 KS
Percent (%)
Knr pH CEC OC Sand Silt Clay
1251210
1453404
362845
2197250
1504538
2449190
6380703
2429456
3127521
1248534
1303532
1255821
719633
2524581
Degradation in Soils
Parameters Soil Properties
Mois-
Initial Temp, ture Percent (%)
n cone. *C G pH CEC OC Sand Silt Clay
                           Volatilization  in Soils
Volatilization Parameters
         KwKp
               Soil Properties
         MoistureBulkTemp.
OC (%)       9     Density    "C     Porosity
                                        215

-------
Compound Name:  Methyl parathion [0-0-dimethy1-0-p-nitrophenyl phosphoro-
                thioate]
Compound Properties:
                                                                     Structure
          263.2
          35-36'C
M.W.
M.P.
B.P.
Sp.  gr.
Vapor pressure
                9.5xlO-6 mm
                  Hg (20C)
                               Water solubility  55-60
                               Low Kow           1.91
                               Chemical  class
                               Chemical  reactivity
                              Adsorption in Soils
      mg/1 (258C;
Adsorption Parameters
13.39
 3.95
 2.72
 3.57
         0.75
         0.85
         0.86
         0.61
                 346.0
                 438.6
                 486.4
                 714.5
                                            Soil Properties
Percent (%)
PH
7.3
5.6
5.6
7.4
CEC
54.7
6.8
5.2
35.8
OC
3.87
0.90
0.56
0.50
Sand
18.4
65.8
93.8
50.7
Silt
45.3
19.5
3.0
16.4
Clay
38.3
14.7
3.2
22.9
                             Degradation in Soils
Degradation Parameters

                   In itial
              n     cone.
                                              Soil Properties
                              Temp.
                               c
                                     Mois-
                                     ture
                                       0
                                                            Percent (%}
                                           PH
CEC
OC   Sand  Silt  Clay
                           Volatilization in Soils
Volatilization Parameters
  K
   w
         KWKD
                                	Soil Properties	
                                         MoistureBulkTemp.
                                OC (%)       6     Density    "C     Porosity
                                        316

-------
Compound Name:  Metobromuron [3-(p-bromophenyl )-l-methoxy-l-methylurea]

Compound Properties:                                                 Structure

          259.1
M.W.
M.P.
8.P.
Sp. gr.
Vapor pressure
               Water solubility  350 ug/1
               Low Kow
               Chemical  class
               Chemical  reactivity
                              Adsorption in Soils
Adsorption Parameters

  K       N       Kor
   52
   09
   20
   95
 4.54
  ,18
  ,12
10.20
         0.58
         0.78
         0.82
         0.82
         0.85
         0.80
         0.82
         0.81
2100
 204
 154
 134
 281
 330
 501
 219
Soil Properties

pH
8.5
8.5
7.9
7.6
7.7
5.1
7.8
4.6

Texture
S
S
S
S
S cl
S
S
S
Percent (%)
OC Sand Silt
0.06
0.58
0.81
0.87
0.93
1.10
0.70
2.67

Clay
9.8
15.0
13.0
6.8
31.5
10.6
18.3
4.5
                             Degradation in Soils
  Degradation Parameters
                                              Soil  Properties
tl/2
                                     Mois-
                     Initial   Temp,   ture
                      cone.     *C      0
                           pH
CEC
                                                             Percent (%)
OCSandSiltClay
                           Volatilization in Soils
Volatilization Parameters
                                                Soil  Properties
                                          Moisture   Bulk     Temp.
                                 OC (%)      0      Density    "C     Porosity
                                        317

-------
Compound Name:  Mono!inuron [3-(p-chlorophenyl)-l-methoxy-l-methylurea]

Compound Properties:                                                 Structure
M.W.      214.6
M.P.
B.P.
Sp. gr.
Vapor pressure
                       Water solubility  580 yg/1
                       Low Kow
                       Chemical  class
                       Chemical  reactivity
                              Adsorption in Soils
Adsorption Parameters

  K       N       Knr
   43
   28
   20
   90
 3.41
 4.19
 6.35
12.70
0.50
0.86
0.60
0.81
0.91
0.82
0.87
0.90
2025
 321
 225
 334
 211
 224
 520
 273
Soil Properties

PH
8.5
8.5
7.9
7.6
7.7
5.1
7.8
4.6

Texture
S
S
S
S
S cl
S
S
S
Percent (%)
OC Sand Silt
0.06
0.58
0.81
0.87
0.93
1.10
0.70
2.67

Clay
9.8
15.0
13.0
6.8
31.5
10.6
18.3
4.5
Degradation in
Degradation
tl/2
Ks
Parameters
n
Initial
cone.
Temp.
c
Mois-
ture
0
Soils
Soil
PH





Properties
CEC

OC
Percent
Sand
(X)
Silt

Clay
                           Volatilization  in Soils
Volatilization Parameters
                                       Soil Properties
                                          Moisture    Bulk      Temp.
                                 OC (%)       6     Density     "C      Porosity
                                        318

-------
Compound Name:  Naphthalene

Compound Properties:

M.W.      128.2
M.P.       80.2'C
B.P.
Sp. gr.
Vapor pressure  4.92x10-2 torr
                  (20'C)
    Water solubility  30 mg/1
    Low Kow           3.37
    Chemical class
    Chemical reactivity
                              Adsorption in Soils
                                         Structure
Adsorption Parameters

  K       N       Knr

                 1300
                Soil Properties
PH
CEC
                           Percent (%)
OC
Sand
Silt
Clay
                             Degradation in Soils
Dearadation Parameters
0.12
125
4
KS n
5.78
0.005
0.173
Initial
cone.
7.0
7.0
25000
Soil Properties
Mots-
Temp, ture Percent (%)
C 0 pH CEC OC Sand Silt Clay
15-25
>25
                           Volatilization in Soils
Volatilization Parameters
     	Soil  Properties	
              MoistureSulkTemp.
     OC  (%)       0      Density    "C     Porosity
                                       319

-------
Compound Name:  Parathion [0,0-Diethyl  0-(p-nitrophenyl)  phosphorothioate]

Compound Properties:                                                 Structure
M.W.      291.3
M.P.        6C
B.P.      37SC
Sp. gr.
Vapor pressure
3.78x10-5 torr
  (20'C)
Water solubility  6.54 ppm
                  24 ppm (25'C)
Low Kow           3.40
Chemical class
Chemical reactivity
                              Adsorption in Soils
Adsorption Parameters
Soil Properties
Percent (%)
K
4.61
8.98
29.16
32.13
201.47
7.67
12.30
38.02
125.90
213.80
457.10
349
18.9
16.3
5.2
N
0.83
0.83
0.88
0.80
0.81
1.04
1.05
1.11
1.05
1.03
1.02
0.95
0.99
1.01
0.98
KOC
904
839
1105
845
1097
1743
1309
2277
3934
4792
3200
799
1166
1124
1264
PH
7.30
6.83
5.00
7.30
6.98
6.2
6.25
6.30
5.20
3.50
3.30
6.1
6.6
6.8
7.0
CEC
5.71
6.10
21.02
37.84
77.34
18.6
26.6
42.8
19.2
21.2
28.9




OC
0.51
1.07
2.64
3.80
18.36
0.44
0.94
1.67
3.20
4.76
14.28
43.7
1.62
1.45
0.41
Sand
77
83
37
21
42
79.6
75.9
69.6
45.6
53.6
63.6
52
71
56
91.5
Silt
15
9
42
55
39
48
3.4
6.8
7.8
12.8
6.8
34
22
30
1.5
Clay
8
8
21
24
19
15.6
20.7
23.6
45.6
33.6
29.6
14
-t
I
14
7
                             Degradation in Soils
  Degradation Parameters
                              Soil Properties
tl/2    KS
 180
 110
                     Mois-
     Initial  Temp,  ture
      cone.    *C      0
                                                             Percent  (%)
       1       20
       0.1     20
                           Volatilization in Soils
Volatilization Parameters
                                Soil Properties
                                          MoistureBulk     Temp.
                                 OC (%)       9      Density     "C     Porosity
                                        320

-------
Compound Name:  PBBs [polybrominated biphenyls]

Compound Properties:
                                                Structure
M.W.
M.P.
B.P.
Sp. gr.
Vapor pressure

Water solubility










Low Kow
Chemical
Chemical

Adsorption
Adsorption Parameters

K N
36ia 1.99
1443 1.89
883 1.77

KOC
2142
3044
7458

PH
7.2
7.1

CEC
72.4
18.1
4.50 13.1

class
react ivi

in Soils
Soil

OC
16.81
4.73
1.18


ty


Properties
Percent (%)
Sand Silt
15.7 50.8
6.1 61.4
1.1 64 . 3







Clay
33.5
32.5
34.6
                             Degradation in Soils
  Degradation Parameters
                         Soil  Properties
tl/2
Initial
 cone.
Temp.
 'C
Mois-
ture
  e
PH
CEC
                                                             Percent (%)
OC   Sand  Silt  Clay
                           Volatilization  in  Soils
Volatilization  Parameters
^Reported in
                           Soil  Properties
                     Mo isture
                                 OC  (%)
                        0
                      "WTF
                      Density
                         Temp.
                          C
                          Porosity
                                        321

-------
Compound Name:  Pentachloroethane

Compound Properties:
                                                Structure
M.W.
M.P.
B.P.
Sp. gr
Vapor


202.3
-29C

.
pressure 3.4 mm
6 mm

Adsorption Parameters

K

N KOC
Water solubility
Low Kow
Chemical class
Chemical reactivity
(20C)
(30'C)
Adsorption in Soils
Soil Properties
Percent (%)
pH CEC OC Sand Silt Clay
                             Degradation in Soils
  Degradation Parameters
                         Soil  Properties
tl/2
                Mois-
Initial   Temp,   ture
 cone.     "C      G
PH
CEC
                                                             Percent (%)
OC   Sand  Silt  Clay
                           Volatilization in Soils
Volatilization Parameters
                           Soil  Properties
                                          MoistureBulkTemp.
                                 OC (%)      3      Density    *C     Porosity
                                        322

-------
Compound Name:  Phenanthrene

Compound Properties:

M.W.     178.2
M.P.     100'C
B.P.     340C
Sp. gr.
Vapor pressure  6.8xlO"4 torr
                  (20C)
    Water solubility  1.6 mg/1
    Low Kow           4.46
    Chemical class
    Chemical reactivity
                              Adsorption in Soils
                                         Structure
Adsorption Parameters

  K       N       Koc
                23000
                Soil Properties
PH
CEC
                           Percent (%)
OC
Sand
Silt
Clay
                             Degradation in Soils
Degradation Parameters
ti/2 Ks n
26 0.027
35 0.198
Initial
cone.
2.1
25000
Temp.
c
15-25
>25
Soil Properties
Mois-
ture Percent (%)
0 pH CEC OC Sand Silt Clay

                           Volatilization in Soils
Volatilization Parameters

         KWKD
    	Soil  Properties	
              MoistureBulkTemp.
    OC  (%)       e      Density    C     Porosity
                                       323

-------
Compound Name:  Phorate [0,0-Diethyl S-[(ethy1thio)methy1 phosphorodithioate;
                di ethyl s-( ethyl thiomethyl )phosphorothiol athionate]

Compound Properties:
                                                                     Structure
M.W.     260.4
M.P.     <-15C
B.P.     75-78C
Sp.  gr.
Vapor pressure  8.4xl0'4 torr
                  (20'C)
Water solubility 20 ppm
50 ppm
Low Kow 3.33
Chemical class
Chemical reactivity
@ room temp
                              Adsorption in Soils
Adsorption Parameters

  K       N       Kn/~
 2.14
 4.86
 8.63
13.73
74.79
         0.94
         0.91
         0.92
         0.88
         1.01
419.6
454.2
326.9
361.3
407.4
                                            Soil Properties
Percent (%)
PH
7.3
6.83
5.00
7.30
6.98
CEC
5.71
6.10
21.02
37.84
77.34
OC
0.51
1.07
2.64
3.80
18.36
Sand
77
83
37
21
42
Silt
15
9
42
55
39
Clay
8
8
21
24
19
                             Degradation in Soils
  Degradation Parameters
tl/2
  18
  14
                     Initial
                      cone.
                                              Soil Properties
Mois-
Temp. ture
C 9 pH CEC
7.1
8.0
Percent (%)
OC Sand Silt Clay
1.5a 20 50 30
2.0a 30 20 50
                           Volatilization in Soils
Volatilization Parameters
                                                Soil Properties
         KwKp                    OC

Reported as OM (OC = OM/1.724).
                                          Mo i s ture   Bulk     Temp.
                                              B      Density     *C     Porosity
                                        324

-------
Compound Name:   Phosmet

Compound Properties:

M.W.
M.P.
B.P.
Sp. gr.
Vapor pressure
Water solubility
Low Kow
Chemical class
Chemical reactivity
                              Adsorption in Soils
                                     Structure
Adsorption Parameters
K N Koc
Soil Properties
Percent (%)
pH CEC OC Sand Silt Clay
                             Degradation in Soils
Degradation
H
12
60
51
Ks
-
Parameters
n
-
Initial
cone.
1
0.1
Temp.
c

Mois-
ture
8

Soil Properties
Percent (%)
pH CEC

OC

Sand Si

It

Clay

                           Volatilization in Soils
Volatilization Parameters

  KW     KWKD
                Soil  Properties
          Moisture   Bulk     Temp.
 QC (%)       e      Density    "C     Porosity
                                       325

-------
 Compound Name:  Picloram  [4-Amino-3,5,6-trichloro-picolinic  acid]

 Compound Propert1es:
M.W. 241.5
M.P.
B.P.
Sp. gr.
Vapor pressure
 oLrucuure
Water solubility 426 mg/1
Low Kow 3.47
Chemical class
Chemical reactivity
Adsorption in Soils
Adsorption Parameters
K
0.6843
0.6643
0.6393
0.6143
0.5293
0.4993
0.2973
0.3143
0.2973
0.043
0.976b
0.533b
0.310b
0.409b
O.llSb
0.070b
0.75
0.49
0.31
0.23
0.24
.0
0.24
0.09
N *
0.841
0.850
0.861
0.822
0.840
0.841
0.886
0.815
0.835
0.92
0.849
0.816
0.829
0.743
0.838
0.596
-
-
_
-
^oc pH
5.60
5.60
5.60
5.68
5.68
5.68
7.40
7.40
7.40
7.14
5.60
5.68
6.97
7.40
6.40
7.14
7.9
6.5
7.9
8.1
8.2
8.0
8.1
6.9
CEC
20
20
20
19
19
19
41
41
41
8
20
19
14
41
12
8




Soil Properties

Percent (%)
OC Sdnd c  i * ^ i . .,
2.44
2.44
2.44
2.09
2.09
2.09
1.39
1.39
1.39
0.54
2.44
2.09
1.39
1.39
0.93
0.54
7.20
6.08
3.75
14.72
2.48
2.41
2.36
1.03
Jill, i, | ay
18
1 0
io
10
97
97
27
33
33
8
18
27
83
33
9
8
n s
20.3
19.2
57.3
15.0
69.5
18 "5
8.0
3These constants are determined at 1:5 soil/solution ratio.
These constants are determined at 1:2 soil/solution ratio.
                                       326

-------
Compound Name:   Picloram [4-Amino-3,5,6-tri'ch1oro-picol inic acid]
                (continued)

                             Degradation in Soils
Degradation Parameters Soil Properties
tl/2
Ks n
0.0025
0.0044
0.0050
0.0354
0.0258
0.0268
0.0269
0.0048
Mois-
Initial Temp, ture
cone. *C 3 pH
4.8
6.3
5.5
5.8
5.8
Percent (%}
CEC OC Sand Silt Clay
1.68
1.10
0.99
1.10
1.10
1.62
                           Volatilization in Soils
Volatilization Parameters        	Soil Properties	
                                          Moisture   Bulk     Temp.
  Kw     KwKp                    OC (%)       9      Density    C     Porosity
                                        327

-------
Compound Name:.  Prometone [2-methoxy-4,6-bis(isopropylamino)-l,3,5-triazine]
Compound Properties:                                                  Structure
M.W. 225.3
M.P.
PKl = 4.3
8. P.
Sp. gr.

Adsorption Parameters

. * N Koc
1.4
0.4
0.5
1.1
0.9
1.3
1.5
1.4
0.7
1.6
1.4
1.5
1.8
1.3
2.1
2.3
1.6
2.7
2.7
2.7
2.4
5.4
7.9
6.7
7.4
9.8
9.5
11.3
11.9
13.1
14.4
18.5
17.2
25.6
21.7
16.7
Vapor pressure
Water solubility 750 ppm






pH
7.0
6.6
6.2
4.9
5.7
5.9
6.1
5.8
6.7
6.2
5.8
6.9
6.4
6.7
6.6
6.5
6.9
6.3
5.7
7.6
7.2
6.8
5.3
7.1
7.1
6.9
6.5
6.5
6.5
5.9
6.8
6.9
6.8
5.6
6.7
6.9
Low KQW
Chemical
Chemical
Adsorption


CEC
25.4
10.2
10.6
11.0
9.2
12.4
14.0
11.0
30.1
13.9
10.3
20.2
21.5
22.3
24.8
25.9
29.2
26.9
27.4
25.7
42.0
44.6
51.3
37.6
li.2
50.4
61.3
82.1
84.3
92.3
94.2
85.1
106.7
120.9
131.1
123.1
1.94
class
reactivity
in Soils
Soil Properties
Percent (%)
OC Sand Silt
0.1
0.4
0.5
0.9
0.9
1.2
1.3
1.5
1.5
1.5
1.0
1.6
1.7
1.8
2.7
3.1
3.4
3.8
4.6
6.5
7.8
9.4
9.9
12.6
13.6
14.0
14.1
15.4
15.8
16.6
18.9
20.0
22.9
23.6
25.9
27.1






Clay
42.8
8.2
15.8
13.9
20.3
28.5
19.3
17.9
27.8
33.5
21.0
22.0
35.2
37.1
61.6
63.4
31.9
25.9
30.2
28.1
53.8
20.1
29.5
28.4
8.1
17.6
31.2
28.7
19.4
31.4
11.2
12.8
7.3
32.1
24.9
18.8
                                       328

-------
Compound Name:  Prometone [2-methoxy-4,6-bis(isopropylamino)-l,3,5-triazine]
                (continued)


	Degradation in Soils	

  Degradation Parameters      	   	Soil Properties	
                                     Mo is-
                     Initial  Temp,  ture               	Percent (%)	
tj/2    Ks      n     cone.    *C      9    pH    CEC    PC   Sand  Silt  Clay
                           Volatilization in Soils
Volatilization Parameters        	Soil Properties	
                                          MoistureBulkTemp.
  Kw     KwKp                    PC (%)      6      Density    C     Porosity
                                       329

-------
Compound Name:   Prometryne [2-methlthio-4,6-bis(isopropylamino)-l,3,5-triazine]
Compound Properties:                                                  Structure
M.W. 241.3
M.P. 118-120'C
PKi = 4.05
B.P.
Sp. gr.

Adsorption Parameters

K N Knc
3.3
1.8
3.1
4.7
6.2
3.8
3.6
6.2
8.2
3.8
4.8
5.8
5.4
5.4
6.2
6.5
8.2
10.2
9.8
12.2
14.2
28.3
39.7
33.1
34.7
56.4
49.2
44.9
47.5
54.9
53.3
63.8
75.1
77.6
106.6
83.8
Vapor pressure
Water solubility 48 ppm






PH
7.0
6.6
6.2
4.9
5.7
5.9
6.1
5.8
6.7
6.2
5.8
6.9
6.4
6.7
6.6
6.5
6.9
6.3
5.7
7.6
7.2
6.8
5.3
7.1
7.1
6.9
6.5
6.5
6.5
5.9
6.8
6.9
6.8
5.6
6.7
6.9
Low Kow
Chemical
Chemical
Adsorption


CEC
25.4
10.2
10.6
11.0
9.2
12.4
14.0
11.0
30.1
13.9
10.3
20.2
21.5
22.3
24.8
25.9
29.2
26.9
27.4
25.7
42.0
44.6
51.3
37.6
11.2
50. *
61.3
82.1
84.3
92.3
94.2
85.1
106.7
120.9
131.1
123.1

class
reactivity
in Soils
Soil Properties
Percent (%)
OC Sand Silt
0.1
0.4
0.5
0.9
0.9
1.2
1.3
1.5
1.5
1.5
1.0
1.6
1.7
1.8
2.7
3.1
3.4
3.8
4.6
6.5
7.8
9.4
9.9
12.6
13.6
14.0
14.1
15.4
15.8
16.6
18.9
20.0
22.9
23.6
25.9
27.1






Clay
42.8
8.2
15.3
13.9
20.3
28.5
19.3
17.9
27.3
33.5
21.0
22.0
35.2
37.1
61.6
63.4
31.9
25.9
30.2
28.1
53.8
20.1
29.5
28.4
8.1
17.6
31.2
28.7
19.4
31.4
11.2
12.8
7.3
32.1
24.9
18.8
                                       330

-------
Compound Name:  Prometryne [2-methlthio-4,6-bis(isopropylamino)-l,3,5-triazine]
                (continued)


	Degradation in Soils	

  Degradation Parameters      	Soil Properties	
                                     Mois-
                     Initial  Temp,  ture               	Percent  (%)	
tj/2     Ks     n.     cone.    'C      9    pH    CEC    QC   Sand  Silt  Clay
       0.0238   -                           7.0         1.16                18
                           Volatilization in Soils
Volatilization Parameters                       Soil Properties
                                          Moisture   Bulk     Temp.
  Kw     KwKp                    PC (%)       0      Density    C     Porosity

^Reported as OM (OC = OM/1.724).
                                       331

-------
Compound Name:   Propazine [2-chloro-4,6-bis(isopropylamino)-l,3,5-triazinej



Compound Properties:                                                  Structure
M.W. 229.7
M.P.
8. P.
Sp. gr.
Vapor pressure

Adsorption Parameters

K N Koc
1.1
0.5
0.9
1.4
1.4
2.3
2.4
1.5
2.7
1.2
2.0
2.1
2.6
3.0
3.9
3.9
3.5
4.3
4.7
5.7
4.9
12.9
16.2
16.5
19.0
20.5
18.0
24.3
21.4
27.4
34.0
31.6
42.8
45.7
42.5
40.0
Water solubility 8.6 ppm (20C)







pH
7.0
6.6
6.2
4.9
5.7
5.9
6.1
5.8
6.7
6.2
5.8
6.9
6.4
6.7
6.6
6.5
6.9
6.3
5.7
7.6
7.2
6.8
5.3
7.1
7.1
6.9
6.5
6.5
6.5
5.9
6.8
6.9
6.8
5.6
6.7
6.9
Low Kow
Chemical
Chemical

Adsorption


CEC
25.4
10.2
10.6
11.0
9.2
12.4
14.0
11.0
30.1
13.9
10.3
20.2
21.5
22.3
24.8
25.9
29.2
26.9
27.4
25.7
42.0
44.6
51.3
37.6
11.2
50.4
61.3
82.1
84.3
92.3
94.2
83.1
106.7
126.9
131.1
123.1

class
reactivity

in Soils
Soil Properties
Percent (%)
OC Sand Silt
0.1
0.4
0.5
0.9
0.9
1.2
1.3
1.5
1.5
1.5
1.6
1.6
1.7
1.8
2.7
3.1
3.4
3.8
4.6
6.5
7.8
9.4
9.9
12.6
13.6
14.0
14.1
15.4
15.8
16.6
18.9
20.0
22.9
23.6
25.9
27.1







Clay




20.3
28.5
19.3
17.9
27.3
33.5
21.0
22.0
35.2
37.1
61.6 -
63.4
31.9
25.9
30.2
28.1
53.8
20.1
29.5
28.4
8.1
17.6
31.2
28.7
19.4
31.4
11.2
12.8
7.3
32.1
24.9
18.8
                                      332

-------
Compound Name:  Propazine [2-ch1oro-4,6-bis(isoprop.ylamino)-l,3,5-triazine]
                (continued)


	Degradation in Soils	

  Degradation Parameters      	   	Soil Properties	
                                     Moi-s_

                     Initial  Temp,  ture               	Percent  (%)	
ti/2     Ks    _n	   cone.    *C      0    pH    CEC    PC   Sand  Silt  C1 ay
       0.0108                               4.8         0.58
       0.0056                               6.5         1.16
                           Volatilization in Soils
Volatilization Parameters        	Soil Properties	
                                          MoistureBulkTemp.
                                 PC (%)       8      Density    C     Porosity
                                       333

-------
Compound Name:   Pyrene (benzo(def)phenanthrene)
Compound Properties:
Structure
M.W. 202.24
M.P. 156*C
B.P.
Sp. gr.
Vapor pressure






6.85x10-7
(3 20C

Adsorption Parameters

K N
42
3000
2500
1500
1400
994
2100
3000
3600
3800
68
3200
2300
2500
760
1065
1155
614
101
71
277
783
504
723
1119
806
1043
994

KOC
32000
92000
130000
110000
120000
11000
76000
130000
120000
120000
12000
110000
120000
110000
62860
51469
50650
32256
67467
64706
57763
82421
76316
59546
59515
48236
43807
67189
Water solubility 0.14 mg/1
Low Kow 4.88
Chemical class
Chemical reactivity
torr

Adsorption in Soils
Soil Properties
Percent (%)
pH CEC OC Sand Silt Clay
0.13
3.27
1.98
1.34
1.20
0.086
2.78
2.34
2.89
3.29
0.57
2.92
1.99
2.26














                                       334

-------
Compound Name:  Pyrene (benzo(def)phenanthrene) (continued)


	Degradation in Soils	

  Degradation Parameters      	   	Soil Properties	
                                     MoTs^
                     Initial  Temp,  ture               	Percent (%)	
tj/2    Ks      n     cone.     *C      9    pH    CEC    PC   Sand  Silt  Clay
 35    0.020    -       3.1
 10.5  0.067    -     500
  3    0.231    -       5
                           Volatilization in Soils
Volatilization Parameters        	Soil Properties	
                                          MoistureBulkTemp.
                                 QC (%)      e      Density    "C     Porosity
                                       335

-------
Compound Name:  Silvex [2,(2,4,5-Trichlorophenoxy)propionic acid]

Compound Properties:
M.W.     269.5
M.P.     181.6'C
8.P.
Sp. gr.
Vapor pressure
                                     Structure
Water solubility
Low Kow
Chemical  class
Chemical  reactivity
                              Adsorption in Soils
140 mg/1  (25"C)
Adsorption Parameters
Soil Properties
Percent (%)
K
42.1
34.2
162
N
0.639
0.987
1.05
KOC
2786
4682
440
PH
6.09
6.07
6.25
CEC
39.6
34.5
42.0
OC
1.51
0.73
36.8
Sand
4.0
6.5
8.3
Silt
79.6
81.5
80.2
Clay
16.4
12.0
11.5
                             Degradation in Soils
  Degradation Parameters
       0.0330
       0.0495
       0.0462
                      cone.
              Soil Properties
Temp.
C

Mois-
ture
0 pH

Percent (%}
CEC OC Sand Silt
1.91
1.62
2.20

Clay
                           Volatilization in Soils
Volatilization Parameters
                Soil Properties
                                          Moisture   Bulk     Temp.
                                 OC (%)       Q     Density     "C      Porosity
                                        336

-------
Compound Name:  Tebuthiuron [l-(5-tert-butyl-l,3,4-thiodiazo1-2-yl)-l,3-
                dimethylurea]
Compound Properties:

M.W.     216.3
M.P.
B.P.
Sp. gr.
Vapor pressure
                                     Structure
Water solubility    2500 ppm (25C)
Low Kow
Chemical class
Chemical reactivity
                              Adsorption in Soils
Adsorption Parameters
Soil Properties
Percent (%)
K
2.4
1.2
0.5
0.1
N Knr
_a
PH
6.3
6.1
6.1
6.7
CEC
9.2
13.3
6.7
0.6
OC
2.55b
2.49b
O.Slb
0.17b
Sand
30
57
58
95
Silt
52.2
30.5
33.8
3
Clay
17.8
12.5
8.2
2
                             Degradation in Soils
  Degradation Parameters      	^
                                     Mois-
                     Initial  Temp,  ture
              Soil  Properties
tl/2
                      cone.
                               c
       0
CEC
                             Percent (%)
OC
Sand  Silt  Cla\
                           Volatilization in Soils
Volatilization Parameters
aAssumed to be 1.
Reported as OM.
                                 OC (%}
         	Soil  Properties
          MoistureBulkTemp.
             e
  Density    *C
             Porosity
                                       337

-------
Compound Name:  Terbacil  [3-tert-butyl-5 chloro-6 methyluraci1]

Compound Properties:
M.W.     216.7
M.P.     175-177'C
B.P.
Sp. gr.
Vapor pressure  4.8x10-' mm
                  Hg (29.5'C)
                                Water solubility   710 mg/1 (25C)
                                Low Kow
                                Chemical class
                                Chemical reactivity
                              Adsorption in Soils
                                                                     Structure
Adsorption Parameters
 _K_

 2.46
 0.38
 0.12
 0.38
_N_

0.88
0.99
0.88
0.93
                 63.6
                 42.2
                 21.4
                 76.0
                                            Soil Properties
Percent (%)
PH
7.3
5.6
5.6
7.4
CEC
54.7
6.8
5.2
35.8
OC
3.87
0.90
0.56
0.50
Sand
18.4
65.8
93.8
50.7
Silt
45.3
19.5
3.0
16.4
Clay
38.3
14.7
3.2
22.9
                             Degradation in Soils
  Degradation Parameters
                                              Soil Properties
tl/2
                                     Mois-
                     Initial  Temp,  ture
                      cone.    "C      0
                                                             Percent
                                   PH
CEC
OC   Sand  Silt
                           Volatilization  in Soils
Volatilization Parameters
                                         	Soil Properties
                                          Moisture
                                 OC (%)
                                              0
                                             Bulk
                                           Density
            Temp.
             "C
             Porosity
                                       333

-------
Compound Name:
       Terbufos [0,0-diethyl S-[(l,l-dimethylethylthio)methyl]
       phosphorodith ioate]
Compound Properties:

M.W.     262.4
M.P.
B.P.
Sp. gr.
Vapor pressure
                                                            Structure
                       Water solubility   5.07
                       Low Kow            3.68
                       Chemical class
                       Chemical reactivity
                              Adsorption in Soils
                                       ppm
Adsorption Parameters
 3.14
10.58
 7.90
20.55
50.79
0.95
0.94
0.96
0.97
0.97
616
989
299
541
277
                                   Soil Properties
Percent (%)
pH
7.3
6.83
5.00
7.30
6.98
CEC
5.71
6.10
21.02
37.84
71.34
OC
0.51
1.07
2.64
3.80
18.36
Sand
77
83
37
21
42
Silt
15
9
42
55
39
Clay
8
8
21
24
19
Degradation in
Degradation
n/2 KS
12
11
Parameters
Initial Temp.
n cone. C


Mois-
ture
e

Soils
Soi
pH
7.1
8.0

1 Properties
Percent (%)
CEC OC Sand Silt
1.5 20 50
2.0 30 20



Clay
30
50
                           Volatilization in Soils
Volatilization Parameters
                                 QC (%)
                                	Soil  Properties
                                 MoistureSulkTemp.
                                 _  _ 0      Density    C
                                                     Poros ity
                                       339

-------
Compound Name:  1,1,1,2-Tetrachloroethane

Compound Properties:

         167.9
M.W.
M.P.
B.P.
Sp. gr.
Vapor pressure
Water solubility
Low Kow
Chemical class
Chemical reactivity
                              Adsorption in Soils
                                                                     Structure
Adsorption Parameters
K N Koc
Soil Properties

pH CEC OC
Percent (%)
Sand Silt Clay
                             Degradation in Soils
  Degradation Parameters
                                              Soil Properties
M/2
                                     Mo is-
                     Initial  Temp,  ture
                      cone.    C      0
            pH
                                                  CEC
                                                             Percent  (%)
Sand_  Silt  Clay
                           Volatilization  in Soils
Volatilization Parameters
                                                Soil Properties
                                          Moisture    Sulk
                                 OC  (%)       9     Density
                                                               Temp.
                                                                       Porosity
                                       340

-------
Compound Name:  1,1,2,2-Tetrachloroethane

Compound Properties:
                                         Structure
M.W.     167.9
M.P.     -42.5/43.8'C
B.P.
Sp. gr.
Vapor pressure  5 mm (20C)
                8.5 mm (30'C)
    Water solubility   2900 mg/1 (20'C)
    Low Kow
    Chemical class
    Chemical reactivity
                              Adsorption in Soils
Adsorption Parameters

  K       N       Koc
                Soil Properties
PH
CEC
                           Percent (%}
OC
Sand
Silt
Clay
                             Dearadation in Soils
  Degradation Parameters
                  Soil Properties
                                     Mois-
                     Initial  Temp,  ture
                      cone.    *C      9    pH
                      CEC
                     OC
                                 Percent (%)
                 Sand  Silt  Clay
                           Volatilization in Soils
Volatilization Parameters
                    Soil  Properties
                         BUTI<	
                                          Moisture
                                 OC (%)       9      Density
                          Temp.
                           c
                                          Porosity
                                        341

-------
Compound Name:   Tetrachloroethylene

Compound Properties:
                                                Structure
M.W. 165.8
M.P. -22.7'
B.P.
Sp. gr.
Vapor pressure

Water solubility 150 mg/1 (25C)
C Low Kow 2.60
Chemical class
Chemical reactivity
14 mm (20'C)
24 mm (30'C)
45 mm (40'C)
Adsorption in Soils
Adsorption Parameters Soil Properties
K N
Percent (%)
Knr pH CEC OC Sand Silt Clay
                             Degradation in Soils
  Degradation Parameters
                         Soil  Properties
tl/2
                Mois-
Initial   Temp,   ture
 cone.     *C      9
pH
CEC
                                                             Percent (%)
OC   Sand  Silt  Cla\
                           Volatilization in Soils
Volatilization Parameters
                           Soil  Properties
                                          Mo i sture   Bulk      Temp.
                                 QC (%)       6     Density     "C      Porosity
                                        342

-------
Compound Name:   Toluene (methylbenzene)

Compound Properties:
                                                                     Structure
          92.1
         -95.1*C
M.W.
M.P.
B.P.
Sp. gr.
Vapor pressure
Water solubility
                10 mm (6.4'C)
                22 mm (20"C)
                40 mm (31.8'C)
Low- Kow
Chemical
Chemical
class
reactivity
           470 mg/1 (16C)
           515 mg/1 (20C)
           2.60
                              Adsorption in Soils
Adsorption Parameters
Soil Properties

Percent w
K
3.52
2.69
0.90
N
1.008
1.002
0.996
Knr
37.4
46.4
155.2
pH CEC
5.4
5.1
4.3
OC Sand
9.40
5.80
0.58
Silt Clay

                             Degradation in Soils
  Degradation Parameters
                                              Soil Properties
                                     M01S-
                     Initial  Temp,  ture
                      cone.    C      0
                                                             Percent (%)
                                                  CEC
                         OC   Sand  Silt  Clay
                           Volatilization in Soils
Volatilization Parameters
                                                Soil Properties
                                          Moisture   Bulk     Temp.
                                 OC (%}       Q     Density     *C      Porosity
                                        343

-------
Compound Name:  1,2,4-trichlorobenzene

Compound Properties:
M.W.     181.4
M.P.      17C
B.P.     213C
Sp. gr.
Vapor pressure
           Water  solubility    49  mg/1
           Low  Kgw              4.02
           Chemcial  class
           Chemical  reactivity
                              Adsorption in Soils
                                                Structure
Adsorption Parameters
K N Kor
9.52 - 865.7

pH CEC
14
Soil Properties
Percent (%)
OC Sand Silt
1.1 9 68


Clay
21
                             Degradation in Soils
  Degradation Parameters
                         Soil  Properties
tl/2
Initial
 cone.
                              Temp.
Mois-
ture
  0
                 Percent (%)
PH
CEC    OC   Sand  Silt  Cla\
                           Volatilization in Soils
Volatilization Parameters
                           Soil Properties
                                 OC (%)
                     Moisture
                         0
                Bulk
               Density
                  Temp.
                   'C
                    Porosity
                                        344

-------
Compound Name:  1,1,1-trichloroethane

Compound Properties:
                                         Structure
M.W.     133.4
M.P.     -32'C
B.P.
Sp. gr.
Vapor pressure  100 mm (20C)
                155 mm (30C)
    Water solubility   4400 mg/1 (20"C)
    Low Kow            2.49
    Chemcial class
    Chemical reactivity
                              Adsorption in Soils
Adsorption Parameters

  K       N       K
                Soil Properties
PH
CEC
                           Percent (%)
OC
Sand
Silt
Clay
                             Degradation in Soils
  Degradation Parameters
                                     Mois-
                     Initial  Temp,  ture
                      cone.    *C      0
                  Soil Properties
                      CEC
                                 Percent (%)
                     OC   Sand  Silt  Clav
                           Volatilization in Soils
Vo1 ati1izat ion Parameters

         KwKQ
     QC (%)
             	Soil Properties
              Moisture
         0
       "BuTlT
       Density
                          Temp.
                Porosity
                                       345

-------
Compound Name:  1,1,2-trichloroethane

Compound Properties:
M.W.     133.4
M.P.     -357-36.7C
B.P.
Sp.  gr.
Vapor pressure  19 mm (20C)
                32 mm (30C)
                40 mm (35*C)
                                     Structure
Water solubility   4500 mg/1 (20C)
Low KQW
Chemcial class
Chemical reactivity
                              Adsorption in Soils
Adsorption Parameters
            Soil Properties
                            PH
    CEC
                                                       Percent (%)
OC
Sand
 Silt
Clay
                             Degradation in Soils
  Degradation Parameters
              Soil Properties
                                     Mois-
                     Initial  Temp,  ture
                      cone.    C      0
            PH
     CEC
                             Percent (%)
   OC
Sand  Silt  Cl_ay
                           Volatilization in Soils
Volatilization Parameters
                Soil Properties
                                          Moisture   Bulk     Temp.
                                 OC (%)      9      Density    "C     Porosity
                                        3*6

-------
Compound Name:  Trichloroethylene

Compound Properties:
M.W.     131.5
M.P.     -87C
B.P.
Sp. gr.
Vapor pressure  20 mm (O'C)
                60 mm (20'C)
                95 mm (30'C)
                                                Structure
           Water solubility   1.10 mg/1  (25C)
           Low KQW            2.29
           Chemcial  class
           Chemical  reactivity
                              Adsorption in Soils
Adsorption Parameters

  K       N       Koc
                       Soil  Properties
       PH
CEC
                                  Percent (%}
OC
Sand
Silt
Clay
                             Degradation in Soils
  Degradation Parameters
                         Soil  Properties
tl/2
                Mois-
Initial   Temp,   ture
 cone.     C       Q
        PH
     CEC
                                                             Percent (%)
   QC   Sand  SjM1  Clay
                           Volatilization in Soils
Volatilization Parameters
                           Soil  Properties
                     MoistureBulk
                                 OC (%)
                        9
                Density
                 Temp.
                  c
                Porosity
                                       347

-------
Compound Name:  Trichloromethane

Compound Properties:                                                 Structure

M.W.     137.4                  Water solubility   1100 mg/1 (25C)
M.P.     -lll'C                 Low Kgw            2.53
B.P.                            Chemcial class
Sp. gr.                         Chemical reactivity
Vapor pressure 0.904 atm (20C)
               1.29 atm (30*C)

	Adsorption in Soils	

Adsorption Parameters     	Soil Properties	
                                                       Percent~T%T
 J<	    N       KQC       pH      CEC      QC       Sand     Silt     Clay
                             Degradation in Soils
  Degradation Parameters      	Soil Properties	
                                     Mois-
                     Initial  Temp,  ture               	Percent  (%)	
        Ks      n     cone.    *C      0    pH    CEC    OC   Sand  Silt  Clay
                           Volatilization  in Soils
Volatilization Parameters        	Soil Properties	
                                          MoistureBulkTempT
                                 OC  (%)   	G     Density    "C      Porosity
                                        348

-------
Compound Name:  Trifluraline [a,a,a-trif1uoro-2,6-dinitro-N, N-dipropyl-p-
                toluidine]
Compound Properties:
Structure
M.W. 335.3 Water solubility :
M.P. 48.5-49C Low Kow
B.P. 139-140C Chemcial class
Sp. gr. Chemical reactivity
Vapor pressure 1.99x10-4 mm
Hg (29.5"C)
Adsorption in Soils
Adsorption Parameters
1 mg/1 (27C)
Soil Properties
Percent (%)
K
2.73
0.46
0.24
1.60
N
1.15
1.05
1.06
1.18
KOC
75.7
50.7
43.2
177.8
pH
7.3
5.6
5.6
7.4
CEC
54.7
0.90
0.56
0.50
OC
3.87
0.90
0.56
0.50
Sand
18.4
65.8
93.8
50.7
Silt
45.3
19.5
3.0
16.4
Clay
38.3
14.7
3.2
22.9

Degradation Parameters
Degradation
in Soils




Soil Properties
Mois-
Initial Temp, ture
ti/2 Ks n cone
375a
90a
2733
75a

Volatilization Parameters

- Kw KwKp
C 0
15
30
15
30
Volatil ization
pH CEC
OC
7.6 11.4 0.93b
7.6 11.4 0.93t>
6.6 19.4 ,
6.6 19.4 .
in Soils
L.28&
L.28b

Soil Propert

OC (%)
Moisture Bui
c 	
9 Density
Percent (%)
Sand
64
64
35
35

ies
Temp.
c
Silt Clay
20
20
45
45



Poros
14
14
20
20



ity
Reported in months.
^Reported as OM.
                                       349

-------
Compound Name:  Carbaryl  [N-methyl-a-napthylurethene]

Compound Properties:
M.W.     201.2
M.P.
B.P.
Sp. gr.
Vapor pressure
                                Water solubility
                                Low KQW
                                Chemcial  class
                                Chemical  reactivity
                              Adsorption in Soils
                             Degradation in Soils
                                                                     Structure
Adsorption
K
4.87x10-6
2.41x10-6
8.98x10-4
8.42xlO-4
109
4.3
2.9
3.4
Parameters
N
0.438
0.432
0.933
0.893
0.97
0.96
0.98
1.08
Kfir
2.85x10-4
1.41x10-4
0.37
0.35
249
265
200
829
8.1
8.1
7.95
7.95
6.1
6.6
6.8
7.0
Soil Properties
CEC
32.0
32.0
11.6
11.6





OC
1.71
1.71
0.24
0.24
43.7
1.62
1.45
0.41
Percent
Sand
51.5
51.5
51.6
51.6
52
71
56
91.5
(%)
Silt
25.3
25.3
21.6
21.6
34
22
30
1.5

Clay
23.2
23.2
27.0
27.0
14
7
14
7
  Degradation Parameters
                                              Soil Properties
tl/2
                                     Mois-
                     Initial  Temp,  ture
                      cone.    C      0
pH
        CEC
                                                             Percent (%)
                        OC   Sand  Silt  Cla\
                           Volatilization in Soils
Volatilization Parameters
                                                Soil Properties
OC (%)
Mo i s ture
    9
         Bulk
        Density
                                                              Tern p .
                                                               "C
                                                                      Porosity
                                        350

-------
Compound Name:   Chlordane

Compound Properties:

M.W.       409.8
M.P.       103-108.8C
B.P.
Sp.gr.
Vapor pressure  1x10-= torr
                                         Structure
    Water solubility  0.056-1.85 ppm
    Low Kow           2.78
    Chemcial  class
    Chemical  reactivity
                              Adsorption in Soils
Adsorption Parameters

  K       N       W
                Soil Properties
PH
CEC
                           Percent (%)
OC
Sand
Silt
Clay
                             Degradation in Soils
  Degradation Parameters
                  Soil  Properties
      0.00072
      0.0020
                                     Mois-
                     Initial  Temp,  ture
                      cone.    C      9
                pH
              CEC
                                 Percent (%}
            OC   Sand  Silt  Clay
                           Volatilization in Soils
Volatilization Parameters
                    Soil Properties
                                          MoistureBulkTemp.
                                 OC (%)       0     Density    C     Porosity
                                       351

-------
Compound Name:
                Diazinon [0,0-diethyl 0-(2-isopropyl-4-methyl-6-pyrimidyl
                phosphorothioate]
Compound Properties:
M.W. 304.4
M.P.
B.P. 83-84C
Sp. gr.
Vapor pressure 4.1xlO~4 (2
1.1x10-3 W


Water solubility 40 ppm
Low KQW
Chemcial class
Chemical reactivity
Adsorption in Soils
Structure



Adsorption Parameters

  1\       IN       i^nf*
325
 20.1
  5.2
  6.7
         1.00
         1.07
         0.99
         1.08
 744
1240
 359
1630
                                            Soil  Properties
Percent (%)
pH CEC
6.1
6.6
6.8
7.0
OC
43.7
1.62
1.45
0.41
Sand
52
71
56
91.5
Silt
34
22
30
15
Clay
14
7
14
7
                             Degradation  in  Soils
  Degradation Parameters
                                               So i1  Properties
tl/2
Ks n
0.0151
0.0067
0.0242
0.0239
0.0239
0.0248
0.0189
0.0260
0.0166
0.0171
Initial
cone.


Temp.
c
25
15








Mois-
ture
9 PH
6.7
6.7
4.3
4.8
6.5
6.5
4.0
5.4
5.6
5.4

Percent (%)
CEC OC Sand Silt Clay
1.80
1.80
1.80
0.58
1.16
1.16
1.22
1.74
4.18
23.2
                            Volatilization  in  Soils
Volatilization Parameters
                                                 Soil
                                  OC  (*)
Moisture
    0
 Properties
"BUTE
                                                     Density
                                              Temp.
                                               C
                  Porosity
                                        352

-------
Compound Name:
       Endrin [l,2,3,4,10,10-hexach1oro-6,7-epoxy-l,4,4a,5,6,7,8,8a-
       octahydroexo-5,8-dimethanonaphthalene]
Compound Properties:
                                                            Structure
M.W.
M.P.
B.P.
Sp. gr
Vapor


376.9
200 C
184'C
.
pressure



c


2x10-7 torr
9 25C

Water solubility 200
Low Kow 5.6
Chemcial class
Chemical reactivity


Adsorption in Soils
ppb 25'C
(calculated)





Adsorption Parameters

  K       N       Knr
11115
222.5
660.5
 90.4
1.08   25435
0.99   13735
1.12   45572
1.03   22049
                                   Soil  Properties
Percent (%)
pH CEC
6.1
6.6
6.8
7.0
OC
43.7
1.62
1.45
0.41
Sand
52
71
56
91.5
Silt
34
22
30
1.5
Clay
14
7
14
7
Degradation in Soils
Degradation
HZ2 	 KS_
Parameters Soil Properties
Mois-
Initial Temp, ture Percent (%)
n cone. *C 0 pH CEC OC Sand Silt Clay
                           Volatilization  in Soils
Volatilization  Parameters
                                       Soil  Properties
                                          MoistureBulkTemp.
                                 OC (%)       Q      Density    "C     Porosity
                                       353

-------
Compound Name:  Mevinphos

Compound Properties:

M.W.     208.1
M.P.
B.P.
Sp. gr.
Vapor pressure
           Water  solubility
           Low  K,
               Qw,
           Chemcial  class
           Chemical  reactivity


         Adsorption  in  Soils
                                                Structure
Adsorption Parameters
Soil Properties
Percent (%)
K
8.8
N KQC
0.95 20.1
PH
6.1
CEC OC
43.7
Sand
52
Silt
34
Clay
14
                             Degradation  in Soils
  Degradation Parameters
                         Soil  Properties
                MOIS-
Initial   Temp,   ture
 cone.     "C     0
                                                              Percent  (%)
                                            pH
                                            "
CEC
 OC   Sand  Silt  Clay
TJ7Z3"
                           Volatilization  in  Soils
Volatilization Parameters
                           Soil Properties
                                          Moisture    Bulk      Temp.
                                 QC  (%)       6      Density     C     Porosity
                                        354

-------
Compound Nane:  a-napthol (1-hydroxynapthalene, 1-napthol

Compound Properties:
                                                                  Structure
M.W.
M.P.
8.P.
Sp. gr.
Vapor pressure
      144.2
       96.1'C
      184'C
              1 mm (94'C)
             10 mm (142C)
            100 mm (206C)
Water solubility
Low Kgw
Chemcial class
Chemical reactivity
866 mg/1
2.85
                              Adsorption in Soils
Adsorption Parameters
                                         Soil  Properties
          N
               Koc
257.4
 76.5
933.3
 18.2
821.5
243.4
 24.7
761.1
489.
650.
100.
 52.
295
163.9
 76.7
243.4
.7
.6
.4
.1
0.441
0.550
0.310
0.609
0.222
0.357
0.563
0.318
0.283
0.313
0.501
0.642
0.387
0.442
0.549
0.357
12435
3355
129625
12133
746818
8007
5146b
80116
74197
50046t>
5340
3120
12395
11074
8522b
20116

PH
7.79
2.74
7.83
8.32
8.34
6.90
4.54
7.79
7.76
5.50
7.60
7.55
6.70
7.75
6.40
6.35

CEC
24
19
33
4
12
12
19
11
15
9
8
9
31
21
3
4

OC
2.07
2.28
0.72
0.15
0.11
3.04
0.48
0.95
0.66
1.30
1.88
1.67
2.38
1.48
0.90
1.21
Percent (%}
Sand Silt Clay
55.2
31.0
68.6
6.8
17.4
52.6
63.6
35.7
39.5
28.6
7.1
21.2
69.1
42.9
22.5
18.6
                             Degradation in Soils
  Degradation Parameters
tl/2
                                  Mois-
                  Initial   Temp,   ture
                   cone.     C       n
                                           Soil  Properties
                                                             Percent (%)
            pH    CEC    OC   Sand  Silt  Clay
                           Volatilization in Soils
Volatilization Parameters
                                 OC (%)
                                             Soil  Properties
                                       Moisture
                                          0
                    "TOTF
                    Density
aOriginally reported in umole instead of
     s and the others are sediments.
          Temp.
           *C
Porosity
                                       355

-------
Compound Name:   PCBs [polychlon'nated biphenyl]
Compound Properties:

M.W.
M.P.
B.P.
Sp. gr.
Vapor pressure
                                     Structure
Water solubility
Low Kow         3.47
Chemcial class
Chemical reactivity
                              Adsorption in Soils
3.54
Adsorption Parameters
Soil Properties
Percent (%)
K N
1300
1290
1370
620
1250
1090
1210
540
1180
990
580
420
1270
1080
650
510

Degradation

Koc
54167
92143
171250
155000
42083
77857
151250
135000
49167
70714
72500
105000
52917
77143
81250
127500

Parameters

pH CEC
6.3
6.1
6.4
6.5
6.3
6.1
6.4
6.5
6.3
6.1
6.4
6.5
6.3
6.1
6.4
6.5
Degradation in

Mois-
OC
2.4
1.4
0.8
0.4
2.4
1.4
0.8
0.4
2.4
1.4
0.8
0.4
2.4
1.4
0.8
0.4
Soils
Soil

Sand
55.0
56.0
-
93.0
55.0
56.0
-
93.0
55.0
56.0
-
93.0
55.0
56.0
_
93.0

Properties

Initial Temp, ture
M/2 KS
n cone
c e
pH
CEC OC
Silt Clay
45 <1.0
44 <1.0
-
6.0 2.0
45 <1.0
44 <1.0
-
6.0 2.0
45 <1.0
44 <1.0
-
6.0 2.0
45 <1.0
44 <1.0
_
6.0 2.0



Percent (%)
Sand Silt Clay
                           Volatilization in Soils
Volatilization Parameters
         KwKp
                 Soil Properties
          Moisture    Bulk
 OC  (%)       0     Density
       Temp.
        C
Porosity
                                       356

-------
Compound Name:  2,4,5-T [2,4,5 tricholorophenoxy acetic acid]

Compound Properties:
M.W.     225.5
M.P.     153C
B.P.
Sp. gr.
Vapor pressure
Water solubility
Low Kow
Chemcial class
Chemical reactivity
                              Adsorption in Soils
  228 ppm (25C)
  0.60
                                     Structure
Adsorption Parameters
Soil Properties
Percent (%)
K
5.023
0.74a
N
0.81
0.85
Kor pH CEC OC Sand Silt
167
92.5
5.9
7.7
3.0
0.8
61
31
Clay
27
30
                             Degradation in Soils
  Degradation Parameters
       0.0289
       0.0330
       0.0330
       0.0495
       0.0414
              Soil  Properties
                                     Mois-
                     Initial  Temp,  ture
                      cone.    "C      0
            PH
            5.5
            5.8
CEC
                             Percent (%)
OC   Sand  Silt  Cla\
      1.91
      1.64
      2.20
      0.99
      1.10
                           Volatilization in Soils
Volatilization Parameters
if tr if

OC (%)
Soil Properties
Moisture Bulk Temp.
0 Density C

Porosity
Reported in terms umoles.
                                       357

-------
                                 APPENDIX B

                                  GLOSSARY
Aggregated  media


Aliphatic compounds



Alkali  earth metals



Alkali  metals


An ions
                       

Aromatic compounds



Autochthonous microorganisms




Autotrophic bacteria
Breakthrough  curves  (BTC)
Media with two
and micropores.

Organic compounds
groups  are  linked
carbon chain.
sets  of  pores,  macropore
 in  which  the characteristic
  in  a  straight  or branched
CA

CAR
The  elements  of  group  II  of  the  periodic
table,  including  beryllium,  magnesium,  and
calcium.

The elements of  group  I of the periodic table
including sodium and  potassium.

Atoms or molecules  that  are negatively charged.

Organic  compounds  in  which  characteristic
groups  are  linked  to  a particular six-member
carbon ring which  contains three double bonds.

That part of soil  microbial community which is
capable of utilizing the refractory humic sub-
stances.  The characteristic of these organisms
is slow and  constant  activity.

Bacteria that  fix the carbon  they  need  for
growth from  carbon  dioxide  and (usually) obtain
their energy from light  (photosynthetic) or the
oxidation   of   inorganic  compounds   (litho-
trophic).

A curve of  C/C0 vs. V/V0 where:
  C  = concentration  of  column effluent
  C0 = concentration  of  column influent
  V  = cumulative outflow volume
  V0 = total  water  volume  in soil column

Constituent  attenuation  achieved.

Constituent  attenuation  required at the site.
                                     358

-------
CASSACI



Cations

CEC



Chelate



CIS

Cometabolism  (cooxidation)



Complex  ions

Critical  Depth


Desorption



Direct photodegradation
EH

Equilibrium




ESP




ET
Exchange (outer  sphere
 complex)
Constituent attenuation  achieved  based  on
assimilation capacity  for  degradation  (SSAC)
treatment for immobilization.

Atoms or molecules  that  are  positively charged.

Cation exchange capacity, usually is expressed
in mill iequivalents  of  cations  per  100 grams
of soil.

A  1igand which  contains two  donor atoms so
arranged that both  coordinate simultaneously to
the same central  elements.

Constituent  level  in  the  contaminated soil.

Metabolism   by  microorganism  of  a compound
that the cell  is unable  to  use as  a source of
energy or an essential nutrient.

Designates all  ions other than  monoatomic ones.

End  of  microbially active   zone,  depth  of
groundwater, or end of soil  zone.

The reverse  process  of  sorption, i.e.,  solute
concentration  decrease  at  the  soil   water
interface.

The excitation of  substrate molecules directly
via  absorption  of  light  particles  or   quanta.
Loss  of  absorbed  energy  by  the  substrate
molecules is via  photodegradation  reaction of
dissociation,  dehalogenation,    isomerization,
oxidation or other  deactivation routes.

Excavation and  hauling of contamined  soils.

A  state  in  which  a  chemical  reaction  and its
reverse reaction  are taking  place at equal
rates,  so  that the  concentration  of reacting
constituents is constant.
Exchangeable sodium  ratio
E3P= 	[Na+](me/l)
     concentration  of  total  cations  (me/1)
xlOO
Exogeneous treatment  for  constituent attenua-
tion.

Ions held loosely in the vicinity of a charged
surface site  by electrostatic  forces.
                                      359

-------
Pick's  Law
Fugacity
Heavy metals



Heterocyclic  compounds


Heterotrophic bacteria



Hydrolysis


Hydrophobia bonding



Hysteresis  (nonsingularity)



Immobilization


Ion pairs



Ionic strength
The concentrations  tend  to diffuse  from high
to low  concentration  regions.   Mathematically
Pick's Law is:

J = 0(3c/5x)

where J = mass  flux
      0 = constant  (diffusion constant)
      x = space coordinate
      c = concentration

A  compound's  chemical  potential  energy  or
"escaping tendency"  expressed  in  units  of
pressure.   Fugacity concepts  allow  a steady-
state   equilibrium  estimation  of   compound
partitioning   in mul ticomponent   environments.

Defined  as  metals  that  precipitated  in acid
solution by  hydrogen  sulfide  (Cd,  Cr,  Cu,
Hg, Mn, Ni,  Pb, and  Zn).

Compounds that  have  ring  structure in which one
member is an  element other  than  carbon.

Bacteria  that  derive  their  energy  and  carbon
for survival and  growth  from decomposition of
organic materials.

Reaction  of  an ion with water  to form a weak
acid or base.

Partitioning  between  a  polar   solvent  (e.g.,
water)  and a nonpolar adsorbent surface  (e.g.,
soil  humus).

Retention of  a residual  on  soil at  a  given
equilibrium  concentration,  when desorption
occurs.

Irreversible  sorption of  pollutants  thus pre-
venting leaching.

Short  range  interactions between  closely adja-
cent  ions usually  in  pairs  (e.g.,  CdC03 ,
         and  CaS0).
Total electrolyte content of  a  solution.
                                      360

-------
Koc                           Normalized Freundlich  adsorption  constant  with
                              respect to organic carbon content  of soil.   Koc
                              is defined as:

                              Koc = (K/oc%) x 100   or

                              KOC = (Kd/oc%) x 100

                              where  K  is  nonlinear  Freundlich  adsorption
                              isotherm (N^l),  K
-------
KWK,
   oc
LC

LD

Ligands


LR

Macro cation


MEGs

Mole

Mutualistic  (symbiotic)
     conditions

Oxidation



Oxidizing agent

Permanent surface  charge


Photodegradation
Polymerization



Recalcitrant compounds

Redox

Redox potential
Parameter  used  interchangeably  with  KwK,j  to
described  the  relative  volatility  rate  of  a
compound.   A  large KWKOC or  KwK
-------
Reducing agent

Reduction



Retardation factor  (R)


Sensitized photooxidation
Sensitizing compounds
Singlet oxygen




SAR

Solubility constant



Sorption
Sorption  isotherm
A substance that does the reduction.

A  process  in  which  the  oxidation  state of
a  substance  is  decreased due to gain of elec-
trons.

The  ratio  between  average pore water velocity
and  average pollutant front velocity.

The  transfer of absorbed light energy from
sensitizing  compounds  to  molecular  oxygen to
form  a  highly reactive  singlet  oxygen species,
followed by the  oxidation of substrate molecule
by singlet oxygen.

Organic  compounds  which  absorb light  in  the
visible region  and  transfer  this  absorbed
energy  to  other  molecules  as they  return to a
low energy or ground  state.  Energy transfer to
molecular  oxygen  yields  reactive  singlet
oxygen.   Examples  of  sensitizers  include
riboflavin and methylene  blue.
A  highly reactive species  of
life  time  of 3 y sec which  is
the  transfer  of  energy from
compound to molecular oxygen.

Sodium adsorption  ratio.
oxygen  with a
formed through
a sensitizing
SSAC
The  product  of the concentration  of  the ions
of a  substance  in  a saturated solution of the
substance.

A  physical/chemical   process  in  which  the
increase  of  solute  concentration  evolves  at
the  soil  water  interface.    Sorption  term  is
used without  distinguishing whether  the process
is exchange,  hydrophobic  bonding,  adsorption,
etc.

A  functional  relation   between  the  amount
adsorbed  per  unit  weight  of soil  (S)  and
the  equilibrium  solution  phase   concentration
(C).   As  an  example, Freundlich isotherm which
is expressed  as:

S = K CN

where K and  N are constants.

Site/soil  assimilative or  attenuation capacity.
                                      363

-------
SSACD                         Assimilative capacity  for  degradation  rate
                              (biodegradation  and  photodegradation)   per
                              unit soil  weight.

SSWI                          Site/soil/waste  interaction.

Stoichiometric                 Pertaining to weight  relations  in  a  chemical
                              reaction.

ti/2                          Half-life time,  the time needed for 50%  of
                              the initial concentration to  degrade.  Usually,
                              the concept  of  ty2 is  associated  with  first
                              order  degradation  rate,  in which case  the  ti/2
                              is  independent  of the  initial  concentration.
                              However,   the  ^\f2 can  De generalized as  for
                              other  rate orders, which is not  independent at'
                              the initial  concentration.   ^1/2 is  a  simple
                              tool  for  comparing  degradation   potential  of
                              different compounds.
                                      364

-------
                              COPYRIGHT NOTICE
Figure 3-4



Table 3-11



Figure 3-5




Table 3-12



Figure 3-6



Figure 3-7



Figure 3-8



Figure 3-9




Table 3-13



Table 3-13a
From  Fundamentals  of Soil Science  by
EditiolT    Copyright  1978  by John  Wi ley
NY.  Used by permission of  the publisher.

From  Fundamentals  of Soil Science  by
Editio"rTCopyright  1978  by John  Wi 1 ey
NY.  Used by permission of  the publisher.
                                        H.  D.  Foth.   Sixth
                                        and  Sons,  New York,
                                        H.  0.  Foth.   Sixth
                                        and  Sons,  New York,
From  The Nature  and  Properties  of  Soils by  N.  C.  Brady.
                '.   Copyr ight  1974 by  Macmillan  Publishing
                York,  NY.  Used  by  permission  of the pub-
Eighth  Edition,
Co.,  Inc.,  New
lisher.
From  Fundamentals  of  Soil Science  by
Edition.
NY. Used
From The
Copyright
NY. Used
Copyright 1978 by
by permission of the
Nature and Propert
John Wiley
publisher.
ies of Soi
1974 by Macmillan Publishing
by permission of the
publisher.
and

Is
Co. ,

Sons,

by N.
Inc. ,

New

York,

C. Brady.
New

York,

From  Fundamentals  of  Soil Science  by
EditioTu    Copyright  1978  by John Wi ley
NY.  Used by permission of the publisher.

From  Fundamentals  of  Soil Science  by
Ed i t io~FT    Copyright  1978  by John B"i 1 ey
NY.  Used by permission of the publisher.
                                        H.  D.  Foth.   Sixth
                                        and  Sons,  New York,
                                        H.  D.  Foth.   Sixth
                                        and  Sons,  New York,
From  "The  Soil  Environment"  by  J.  L.  Ahlrichs,  p.  3-26  in
Organic Chemicals  in the Soil Environment   edited  by   C.A.I,
Goring and J.vTHamaker.Copyright 1972 by Marcel  Dekker,
Inc.,  New  York,  NY.    Used  by permission  of the publisher.

From  Concepts in Soil  Science  by  M.  G. Cook  and G.  M. Pace.
Copyright 1978  by  North  Carolina State University,  Raleigh,
NC.  Used by  permission of the publisher.

From  "Chemical,   Spectroscopic, and   Thermal  Methods  for  the
Classification  and Characterization  of  Humic  Substances"
by M.  Schnitzer, p. 293-310 in Humic Substances,  Their  Struc-
ture and
H.
L.
Go
Function
Iterman.
in the
Copyr
Biosphere
Tght
1975
ed i ted by
by Center
D.
for
Povoledo and
Agricultural
                                        365

-------
Figure 3-10



Table 3-14



Table 3-15



Figure 3-11



Figure 3-12



Table 3-17




Figure 3-14
Figure 3-15



Figure 3-16




Figure 3-17




Table 3-29
                Publishing  and  Documentation,
                of  the  publisher.
                              Wageningen.  Used by permission
From  The Nature  and Properties of Soils  by  N.  C.  Brady.
Eighth Edition.
Inc., New  York,
                 Copyright  1974  by Macmi1 Ian Publishing Co.,
                 NY.   Used by  permission  of  the puolisher.
From "The  Mechanism  of Reduction  in  Waterlogged Paddy Soil"
by  Y.  Takai  and  T.  Kamura.    Folia  Microbiol.  (Prague)  11:
135-145,  1966.   Used  by  permission of Folia  Microbiologica.
From  Soil
W.  L.
Inc.,  New
           Fertility
       Nelson.
      Copyright  1975
York, NY.   Used  by
and Fertilizers by  S.  L. Tisdale and
          by  Macmillan  Publishing Co.,
          permission  of  the  publisher.
From Physical Edaphology by S.  A.  Taylor  and G. L. Ashcroft.
Copyright 1972 by  W.  H.  Freeman and  Co.,  San Francisco, CA.
Used by permission  of  the publisher.
From  Fundamentals  of Soil  Science  by
Edition.
NY.  Used
           Copyright  1978
          by permission of
               by~John  Wiley
               the publisher.
                   H.  D.  Foth.   Sixth
                   and  Sons,  New York,
From Soil and Hater Conservation Engineering by G. 0. Schwab,
R.  K.  Frevert, T.  W.  Edminster,  and  K. K.  Barnes.   Second
Edition.   Copyright 1966 by  John  Wiley and  Sons,  Inc., New
York, NY.  Used by permission  of the  publisher.

From  "Factors  Affecting  the  Solubility  of Trace  Metals  in
Soils"  by S.  W.  Mattigod, G.  Sposito, and  A. L.  Page  in
Chemistry in the_Soj_1  Envi ronment.    ASA  Special  Publication
7RT,r98l.   Used  by pe>mi ssion of  the  American Society  of
Agronomy.
          	Equilibria  in Soi 1 s
       1979  by John" Wiley""and
permission of the publisher.
From Chemical
right
                        by  W.  L.  Lindsay.    Copy-
                    "Sons,  New York, NY.   Used  by
From "The Chemistry of Lead and Cadmium in  Soil:   Solid  Phase
Formation" by  J.  Santil lan-Medrano and J.  J.  Jurinak.   Soil
Sci. Soc. Am. Proc.  29:851-856, 1975.   Used by permission  of
the Soil Science Society of America.

From "The Chemistry of Lead and Cadmium in  Soil:   Solid  Phase
Formation" by  J.  Santillan-Medrano and J.  J.  Jurinak.   Soil
Sci. Soc. Am. Proc.  29:851-856, 1975.   Used by permission  of
the Soil Science Society of America.

From  "Factors   Affecting  the  Solubility  of Trace Metals  in
Soils" by S. W. Mattigod,  G.  Sposito,  and  A. L.  Page in  Chem-
istry in the Soil  Environment.   ASA  Special  Publication40,
1981.Used by permission of the American  Society of Agronomy.
                                       366

-------
Figure 3-18
Figure 3-19
Figure 3-20
Figure 3-21
Table 3-30
Table 3-31
Table 3-32
Figure 3-22
Figure 3-23
From  "Chloride  as  a Factor  in  Mobilities of Ni(II),  Cu(II),
and  Cd(II)  in  Soil"  by H.  E.  Doner.   Soil  Sci.  Soc.  Am.  J.
42:882-885,  1978.    Used  by  permission  of  the  SoilScience
Society of America.
From  "Chloride  as a Factor  in  Mobilities of Ni(II),
and  Cd(II)  in  Soil"  by H.  E.  Doner.   Soil  Sci.  Soc
42:882-885,  1978.    Used  by  permission
Society of America.
 Cu(II),
.  Am.  J.
                                                         of the  Soil  Science
From  "Chloride  as a Factor  in  Mobilities of Ni(II),  Cu(II),
and  Cd(II)  in  Soil"  by H.  E.  Doner.   So i 1  Sci.  Soc.  Am.  J.
42:882-885,  1978.    Used  by  permission of  the  SoilScience
Society of America.

From  "Heterogeneous  Equilibria  Involving  Oxides,  Hydroxides,
Carbonates  and  Hydroxide Carbonates"  by  P.  W.  Schindler  in
Equilibrium Concepts in Natural  Water Systems  edited by  R.  F.
Gould.Adv. in Chem. Ser.  No. 67.Copyright  1967  by American
Chemical  Society,  Washington,  DC.   Used by permission  of  the
American Chemical Society.

From  "Trace  Metal  Complexation  by Fluvic  Acid Extracted  from
Sewage  Sludge:    I.  Determination  of Stability Constants  and
Linear  Correlation  Analysis"  by G.  Sposito,  K.  M.  Holzclaw,
and  C.  S.  LeVesque-Madore.   Soil  Sci. Soc. Am. J.  45:465-468,
1981.   Used  by permission  of the  Soil  Science  Society  of
America.

From  "Factors  Affecting  the Solubility of  Trace  Metals  in
Soils"  by  S.  W.  Mattigod,   G.  Sposito,  and A.  L.  Page  in
Chemistry in the Soil Environment.     ASA  Special   Publication
7U^1981.Used by permission of  the American  Society  of
Agronomy.

From  "Soil  Adsorption  of  Cadmium  from Solutions  Containing
Organic Ligands"  by H. A.  Elliott  and  C.  M. Denneny.   _J_i
Environ. Qual.  11:658,663, 1982.   Used  by permission  of  the
Journal of Environmental Quality.

From  "Soil  Adsorption  of  Cadmium  from Solutions  Containing
Organic Ligands"  by H. A.  Elliott  and  C.  M. Denneny.   J_._
Environ. Qua!.  11:658-663, 1982.   Used  by permission  of  the
Journal of Environmental Quality.

From  "Copper  and Cadmium  Reactions with Soils in  Land  Appli-
cations"  by F.  S.  Tirsch,  J.  H.  Baker,  and F.  A.  Diglano.
J. Water Pollution Control  Fed.  51:2649-2660, 1979.   Used  by
                                              Control  Federa-
                permission
                tion.
                           of the  Journalof  Water Pollution
                                        367

-------
Table 3-33      From "Effect of  Soil  pH on Adsorption  of Lead, Copper,  Zinc
                and  Nickel" by R. D. Harter.   Soil  Sci.  Soc. Am. J.  47:47-51,
                1983.   Used by  permission  of the Soil  Science  Society  of
                America.

Figure 3-24     From "Copper  and Cadmium  Adsorption  Characteristics  of  Se-
                lected  Acid and  Calcareous  Soils"  by  N.  Cavallaro and M.  B.
                McBride.    Soil  Sci. Soc.  Am.  J.  42:550-556,  1978.   Used  by
                permission of the Soil  Science  Society  of America.

Figure 3-25     From "Copper  and Cadmium  Adsorption  Characteristics  of  Se-
                lected  Acid and  Calcareous  Soils"  by  N.  Cavallaro and M.  B.
                McBride.    Soil  Sci. Soc.  Am.  J.  42:550-556,  1978.   Used  by
                permission of the Soil  Science  Society  of America.

Table 3-34      From "Copper  and Cadmium  Adsorption  Characteristics  of  Se-
                lected  Acid and  Calcareous  Soils"  by  N.  Cavallaro and M.  B.
                McBride.    Soil  Sci. Soc.  Am.  J.  42:550-556,  1978.   Used  by
                permission of the Soil  Science  Society  of America.

Table 3-35      From "Soil  Sorption  of  Nickel:   Influence of Solution  Compo-
                sition"  by R.  S.  Bowman, M. E. Essington, and G. A.  O'Connor.
                Soil Sci.  Soc. Am. J.  45:860-865,  1981.   Used  by  permission
                of the  Soil  Science  Society of  America.

Table 3-36      From "Soil  Sorption  of  Nickel:   Influence of Solution  Compo-
                sition"  by R.  S.  Bowman, M. E.-Essington, and G. A.  O'Connor.
                Soil Sci.  Soc. Am. J.  45:860-865,  1981.   Used  by  permission
                of the  Soil  Science  Society of  America.

Table 3-37      From "Influence  of  Solution Composition  on  Sorption of  Zinc
                by  Soil"  by M.   A.  Elrashidi  and  G. A.  O'Connor.    Soil  Sci.
                Soc. Am.  J.  46:1153-1158,  1982.    Used by  permission  of  the
                Soil Science Society of America.

Figure 3-28     From "The  Chemistry of  Soil  Processes"  by D.  J.  Greenland
                and  M.  H.  B. Hayes.   John  Wiley and Sons,  Chichester, England,
                1981.  Used by permission  of the  publisher.

Figure 3-29     From "Behavior  of  Chromium  in  Soils:    I.  Trivalent  Forms,
                II.   Hexavalent  Forms"  by  R.  S.  Bartlett and  J.  M.  Kimble.
                J. Environ.  Qual. 5:379-386,  1976.    Used  by  permission  of
                the Journal  of  Environmental  Quality.

Figure 3-31     From "Behavior  of  Chromium  in  Soils:    I.  Trivalent  Forms,
                II.   Hexavalent  Forms"  by  R.  S.  Bartlett and  J.  M.  Kimble.
                J. Environ.  Qual. 5:379-386,  1976.    Used  by  permission  of
                the Journal  of  Environmental  Quality.

Table 3-38      From "Volatility  of Mercury from  Soils  Amended with  Various
                Mercury Compounds"  by  J.  D.  Rogers.    Soil Sci.  Soc.  Am.  J.
                43:289-291, 1979.    Used  by  permission   of  the Soil  Science
                Society of America.
                                       268

-------
Figure 3-37     From  "Solubility  and  Redox  Criteria  for  the  Possible  Forms
                of Selenium  in  Soils"  by H.  R. Geering, E.  E.  Cory,  L.  H.  P.
                Jones, and W.  H.  Alloway.   Soil  Sci. Soc.  Am. Proc. 32:35-40,
                1968.   Used by permission  of the  Soil Science Society  of
                America.

Table 3-39      From "Interaction of Organic  Pesticides with Particular Matter
                in Aquatic and  Soil Systems"  by J. 8. Weber in Fate of Organic
                Pesticides in the Aquatic Environment  edited  by R. F!Gould.
                Copyright 1972  by American Chemical   Society,  Washington,  DC.
                Used by permission of  the American Chemical  Society.   Used  by
                permission of the author.

Figure 3-38     From "Interaction of Organic  Pesticides with Particular Matter
                in Aquatic and  Soil Systems"  by J. B. Weber in Fate of Organic
                Pesticides in the Aquatic Environment  edited  by R.F!Gould.
                Copyright 1972  by ^American  Chemical   Society,  Washington,  DC.
                Used by permission of  the American Chemical  Society.   Used  by
                permission of the author.

Table 3-40      From "Interaction of Organic  Pesticides with Particular Matter
                in Aquatic and  Soil Systems"  by 0. B. Weber in Fate of Organic
                Pesticides in the Aquatic Environment  edited  by R.F!Gould.
                Copyright 1972  by~ Amerfcan  Chemical   Society,  Washington,  OC.
                Used by permission of  the American Chemical  Society.   Used  by
                permission of the author.

Table 3-41      From "Interaction of Organic  Pesticides with Particular Matter
                in Aquatic and  Soil  Systems"  by J. B. Weber in Fate of Organic
                Pesticides in the Aquatic Environment edited  by R. F.  Gould.
                Copyright 1972  by American  Chemical   Society,  Washington,  DC.
                Used by permission of  the American Chemical  Society.   Used  by
                permission of the  author.

Table 3-42      From "Interaction  of Organic  Pesticides with Particular Matter
                in Aquatic and  Soil  Systems"  by J. B. Weber  in Fate of Organic
                Pesticides in the  Aquatic Environment edited  by~~R~;F.  Gould.
                Copyright 1972   by American  Chemical   Society,  Washington,  DC.
                Used by permission of  the American Chemical  Society.   Used  by
                permission of the  author.

Table 3-43      From "A Survey of Sorption Relationships for  Reactive  Solutes
                in Soils"  by  C.  C. Travis and E. K. Etnier.   J.  Environ.  Qua!.
                10:8-17,  1981.   Used by permission of  the Journal  of  Environ-
                mental  Qua!ity.

Figure 3-39     From "Studies in  Adsorption.    Part XI. A System of Classifi-
                cation  of Solution Adsorption  Isotherms  and Its Use  in  Diag-
                nosis  of Adsorption Mechanisms  and in  Measurement  of  Specific
                Surface Areas of  Solids" by H.  Giles, T,  H.  MacEwan, S.  N.
                Nakhaw,  and  D.  Smith.   J.  Chem. Soc.  111:3973-3993,  1960.
                Used  by permission of the Royal Society of  Chemistry,  London,
                England.
                                       369

-------
Figure 3-40     From  "Interaction  of Organic Pesticides with Particular Matter
                in  Aquatic  and  Soil Systems" by J. B. Weber  in Fate of Organic
                Pesticides  in the  Aquatic Environment edited by  R.F.  Gould.
                Copyright1972  by American  Chemical  Society,  Washington, DC.
                Used  by permission of  the American Chemical  Society.   Used by
                permission  of the  author.

Table 3-45      From   "Factors  Influencing  the  Adsorption, Desorption,  and
                Movement  of Pesticides  in  Soils" by G.  W.  Bailey and  J. L.
                White.  Residue Reviews  32:29-93.  Copyright 1970 by Springer-
                Verlag  New .York,   Inc.   Used by  permission  of  the publisher.

Figure 3-43     From  "Estimation  of   Pesticide  Retention  and  Transformation
                Parameters  Required  in  Non-Point  Source  Pollution  Models" by
                P.  S.  C.  Rao  and J.  M. Davidson  in Environmental Impact of
                Nonpoint Source Pollution edited  by M.  R. Overcash  and  J. M.
                Davidson.Copyright19150   by  Ann Arbor  Science  Pub.,   Inc.,
                Ann Arbor,  MI.  Used by  permission of the  publisher.

Figure 3-44     From  "Increased  Cooxidative Biodegradation  of  Malathion in
                Soil  via Cosubstrate  Enrichment"  by G.  J.  Merkel  and  J. J.
                Perry.   J. Agr.  Food Chem.  25:1011-1012, 1977.   Used by
                permission  of the  American Chemical Society.

Figure 3-45     From  "Increased  Cooxidative Biodegradation  of  Malathion in
                Soil  via Cosubstrate  Enrichment"  by G.  J.  Merkel  and  J. J.
                Perry.   J. Agr.  Food Chem.  25:1011-1012, 1977.   Used by
                permission  of the  American Chemical Society.

Table 3-46      From  "Biodegradation  of  Polynuclear Aromatic Hydrocarbon  Pol-
                lutants by  Soil  and  Water  Microorganisms"  by  E.  J.  McKenna.
                Presented  at the   70th Annual  Meeting of  the Am.  Inst.   Chem.
                Eng.,  New  York, NY.   Used  by permission  of the  American In-
                stitute of  Chemical Engineers.

Figure 3-46     From  "Turnover  of  Pesticide  Residues  in Soil" by J. W. Hamaker
                and C.  A.   I. Goring in  Bound and Conjugate  Pesticide Residues
                edited by  D.  0.   Kaufman et  al .  ACS Symposium Series 29.
                Copyright  1976  by American  Chemical  Society,  Washington, DC.
                Used  by permission of  the American Chemical  Society.

Figure 3-47     From  "Turnover  of  Pesticide  Residues  in Soil" by J. W. Hamaker
                and C.  A.   I. Goring in  Bound and Conjugate  Pesticide Residues
                edited by  D.  D.   Kaufman et  al .  ACS Symposium Series 29.
                Copyright  1976  by American  Chemical  Society,  Washington, DC.
                Used  by permission of  the American Chemical  Society.

Figure 3-49     From   Design of Land Treatment Systems for Industrial Wastes  -
                Theory and  Practice by M. R. Qvercash  and D.  Pal .   Copyright
                1979  by Ann Arbor Science Pub.,  Inc., Ann Arbor,  MI.   Used by
                permission  of the  publisher.
                                        370

-------
Table 3-49      From "Land  Disposal  of  Acidic Basic   and Salty  Wastes  from
                Industries"  by D.  Pal,  M.  R.  Overcash, and  P.  W.  Westerman.
                Manuscript  originally printed  in  the  Proceedings of  the
                National  Conference on Treatment and Disposal of Industrial
                Wastewaters  and Residues^   1977.    Avai1ab1e  from  Hazardous
                MaterialsControlResearch Institute,  9300 Columbia  Blvd.,
                Silver  Spring,  MD 20910.   Used by permission  of the Hazardous
                Materials  Control  Research  Institute.

Table 3-50      From "Dissolution  of  Clay Minerals  in Dilute  Organic  Acids
                at Room Temperature" by  W. H. Huang  and  W.  D. Keller.   The
                Am.  Mineralogist  56:1082-1095.   Copyright 1971  by the  MlrP
                eralogicalSociety  of  America.   Used  by permission  of  the
                Mineralogical  Society of America.

Figure 3-50     From Design of Land Treatment Systems for Industrial  Wastes  -
                Theory  and Practice  by  M.  R.  Overcash  and D.  Pal .   Copyright
                1979 by Ann Arbor Science Pub., Inc.,  Ann  Arbor, MI.   Used
                by permission of  the publisher.

Table 3-52      From Design of Land Treatment Systems for Industrial  Wastes  -
                Theory  and Practice  by  M.  R.  Overcash  and D.  Pal .   Copyright
                1979 by Ann Arbor Science Pub., Inc.,  Ann  Arbor, MI.   Used
                by permission of  the publisher.

Table 3-53      From Design of Land Treatment Systems for Industrial  Wastes  -
                Theory  and Practice  by  M.  R.  Overcash  and D.  Pal.Copyright
                1979 by Ann Arbor Science Pub., Inc.,  Ann  Arbor, MI.   Used
                by permission of  the publisher.

Table 3-.S7      From "Adsorption  of Surfactants on Montmoril lonite" by W. F.
                Hower.    Clays and Clay  Minerals  18:97-105,  1970.    Used by
                permission of the  Clay Minerals Society.

Table 3-58      From  "Influence  of  Methods of Pesticide Application on  Sub-
                sequent Desorption from  Soils" by  B. T. Bowman and W. W.
                Sans.   J. Agr.  Food Chem.  30:147-150.   Copyright 1982 by
                American  Chemical  Society, Washington,  DC.   Used by  permis-
                sion of the American Chemical  Society.

Figure 3-51      From  "Influence  of  Methods of  Pesticide Application on  Sub-
                sequent Desorption from  Soils" by  B. T. Bowman  and W. W.
                Sans.   J. Agr.  Food Chem.  30:147-150.   Copyright 1982 by
                American  ChemicalSociety, Washington,  DC.   Used by  permis-
                sion of the American Chemical  Society.

Figure 3-52      From  "Influence  of Methods of  Pesticide Application on Sub-
                sequent Desorption from  Soils" by  B. T. Bowman  and W. W.
                Sans.   J. Agr.  Food CheriK  30:147-150.   Copyright  1982 by
                American  ChemicalSociety, Washington, DC.   Used by permis-
                sion of the American Chemical  Society.
                                      371

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Figure 3-53     From "Mechanisms  of Solute  Transport  in  Soils"  by  D. R.
                Nielsen,  J.  W.  Biggar, and  C.  S.  Simons  in Model ing Waste-
                water Renovation Land Treatment  edited  by   I.  FTIskandar.
                Copyright  1981 by  Wi ley-Interscience, New  York,  NY.   Used by
                permission  of the  publisher.

Figure 3-54     From "Soil   Hydraulic  Properties,  Spatial   Variability,  and
                Soil-Water  Movement"  by 0. R. Nielsen, J.  Matthey, and  J. W.
                Biggar  in Modeling  Wastewater Renovation Land Treatment edited
                by I.  K.  Iskandar.Copyright 1981 by Wiley-Interscience, New
                York, NY.   Used by  permission of the  publisher.

Figure 3-55     From "Soil   Hydraulic  Properties,  Spatial   Variability,  and
                Soil-Water  Movement"  by D. R. Nielsen, J.  Matthey, and  J. W.
                Biggar  in Modeling  Wastewater Renovation Land Treatment edited
                by I.  K.  Iskandar.Copyright 1981 by Wiley-Interscience, New
                York, NY.   Used by  permission of the  publisher.

Figure 3-56     From "Evaluation  of  Conceptual  Process Models  for Solute Be-
                havior  in Soil-Water  Systems" by M. M. Davidson, P.  S. C.  Rao,
                R. E.  Green, and  H. M.  Selim in Agrochemicals in Soils edited
                by A. Banin and U.  Kafkafi.  Copyright 1980 by Pergamon Press,
                London.   Used by permission of the publisher.

Table 3-60      From "Empirical  Equations  for. Some Soil  Hydraulic  Properties"
                by R.  B.  Clapp and 6.  M.  Hornberger.  Water Resour. Res. 14:
                601-604.   Copyright 1978 by American* Geophysical  Union.Used
                by permission of the  American Geophysical Union.

Figure 3-57     From   Chemodynamics,  Environmental Movement of Chemicals in
                Air, Water  and Soil  by  C  T.  Thibodeaux.    Copyright 1979 by
                John Wiley  and Sons,  New York,  NY.   Used  by permission of the
                publisher.

Table 3-62      From "Vapor-Phase Photochemistry  of Pesticides"  by  J. E.
                Woodrow,  D.  G.  Crosby,  and  J.  N.   Seiber.   Residue Reviews
                85:111-125.  Copyright  1983 by Springer-Verlag New York,  Inc.
                Used by permission  of the  publisher.
                                          372

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