Hazard Ranking System Issue Analysis:
Alternative Methods for Ranking the Persistence
of Hazardous Substances in Surface Water
MITRE
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Hazard Ranking System Issue Analysis:
Alternative Methods for Ranking the Persistence
of Hazardous Substances in Surface Water
Ming P. Wang
November 1987
MTR-86W172
SPONSOR:
U.S. Environmental Protection Agency
CONTRACT NO.:
EPA-68-01-7054
The MITRE Corporation
Civil Systems Division
7525 Colshire Drive
McLean, Virginia 22102-3481
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Department Approval:
MITRE Project Approval:
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ABSTRACT
This report addresses possible modifications to the persistence
ranking method in the current HRS to better reflect the environmental
attenuation potential of hazardous substances in surface water. The
joint effect of several important processes, including
biodegradation, hydrolysis, photolysis, volatilization, free-radical
oxidation, and sorption, is evaluated using steady-state models for
idealized water bodies. Two alternatives are proposed which rank the
persistence of substances according to the expected change of
substance concentration over the HRS target distance limit.
Alternative I considers all six processes mentioned above. Its
application requires field measurements to quantify the fraction of
substance sorbed and the subsequent sedimentation loss of the sorbed
chemicals. Alternative II considers all processes except sorption;
its application does not require field measurements. In streams and
rivers, the majority of substances are expected to be ranked as
persistent (i.e., less than 50 percent reduction in concentration)
unless sedimentation loss of the sorbed substances is significant.
In general, substances are expected to be less persistent in lakes
and reservoirs than in streams and rivers because of the longer
reaction time in lakes and reservoirs and because lakes and
reservoirs are good sediment traps.
Suggested Keywords: Persistence, Chemical persistence, Hazard
substance ranking, Hazard Ranking System.
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ACKNOWLEDGEMENT
The author wishes to thank Lawrence Kushner and Stu Haus for
their guidance and William W. Duff, Gerald R. Goldgraben, Denton
Langridge, Steve McBrien, Andrew M. Platt, David C. Roberts, and
Vicki Ziegenhagen of The MITRE Corporation for their assistance in
the preparation of this report.
Additionally, the author wishes to thank Francois M. M. Morel
and David A. Dzombak of Massachusettes Institute of Technology, and
Bob Ambrose and Dave Brown of EPA-ERL at Athens, Georgia, for
contributing helpful information.
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TABLE OF CONTENTS
Page
LIST OF FIGURES vii
LIST OF TABLES viii
1.0 INTRODUCTION 1
1.1 Background 1
1.2 Issue Description 3
1.3 Objectives of the Study 5
1.4 Scope of Work 6
1.5 Approach 6
1.6 Review of Persistence Factors in Other Ranking Systems 8
1.7 Organization of the Report 12
2.0 MECHANISMS AFFECTING THE PERSISTENCE OF HAZARDOUS 15
SUBSTANCES IN A SURFACE WATER ENVIRONMENT
2.1 Introduction 15
2.2 Mode gradation, Hydrolysis, Photolysis, Free-Radical 21
Oxidation, and Volatilization
2.3 Sorption 25
2.3.1 Organics 28
2.3.2 Metals 29
2.4 Effect of Sorption on Other Transformation Processes 32
3.0 MODELS OF SUBSTANCE FATE FOR IDEALIZED WATER BODIES 37
3.1 Overview 37
3.2 Streams and Rivers 38
3.2.1 General Model, Considering Both Settling and Decay 39
3.2.2 Model With Decay Only 41
3.2.3 Model With Settling Only (i.e., No Decay) 42
3.2.4 Model With Settling Only, With Partition 43
Coefficient as a Function of Suspended Solids
Concentration
3.3 Lakes and Reservoirs 44
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TABT.F, OF CONTENTS (Concluded)
4.0 ALTERNATIVES TO THE CURRENT HRS PERSISTENCE RANKING 49
METHOD FOR THE SURFACE WATER PATHWAY
4.1 Overview 49
4.2 Alternative I 50
4.2.1 Streams and Rivers 51
4.2.2 Lakes and Reservoirs 59
4.3 Alternative II 64
5.0 DISCUSSION AND CONCLUSIONS 71
5.1 Comparison of the Two Alternative Persistence Ranking 71
Methods
5.2 Comparison With the Current HRS Persistence Ranking Method 73
6.0 BIBLIOGRAPHY 83
APPENDIX A—REVIEW OF PERSISTENCE FACTORS IN OTHER SITE 91
RANKING SYSTEMS
APPENDIX B--ILLUSTRATIVE HALF-LIVES OF SUBSTANCES IN 101
STREAMS/RIVERS
APPENDIX C—ILLUSTRATIVE HALF-LIVES OF SUBSTANCES IN 111
LAKES/RESERVOIRS
APPENDIX D—LOGARITHM OF N-OCTANOL-WATER COEFFICIENTS LOG Pow 121
APPENDIX E—-THE SELECTION OF METHODOLOGY IN ESTIMATING 139
PARTITION COEFFICIENT OF METALS
APPENDIX F—TIME OF TRAVEL IN STREAMS AND RIVERS OF THE 145
SURFACE WATER PATHWAY
APPENDIX G—METHODOLOGY FOR CALCULATING HALF-LIVES 149
APPENDIX H—GLOSSARY 155
VI
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LIST OF FIGURES
Figure Number Page
1 A SCHEMATIC DIAGRAM SHOWING THE IMPORTANT 40
PROCESSES AFFECTING FATE OF SUBSTANCES IN A
SURFACE WATER BODY
2 A SCHEMATIC DIAGRAM SHOWING THE IMPORTANT 45
PROCESS AFFECTING FATE OF SUBSTANCES IN AN
IDEALIZED LAKE OR RESERVOIR
3 PERSISTENCE RANKING METHOD FOR SUBSTANCES IN 52
STREAMS AND RIVERS—ALTERNATIVE I
4 MEAN CONCENTRATION OF SUSPENDED SEDIMENT AT 57
NASQAN STATIONS DURING 1976 WATER YEAR. MAP AT
BOTTOM IS CODED TO SHOW MEAN DATA FOR STATIONS
REPRESENTING FLOW FROM THE ACCOUNTING UNIT
5 PERSISTENCE RANKING METHOD FOR SUBSTANCES IN 60
LAKES AND RESERVOIRS—ALTERNATIVE I
6 CHURCHILL'S TRAP EFFICIENCY CURVE 63
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LIST OF TABLES
Table Number Page
1 SUMMARY OF PERSISTENCE FACTORS IN OTHER 10
RANKING SYSTEMS
2 RELATIVE IMPORTANCE OF PROCESSES AFFECTING 16
THE FATE OF PRIORITY POLLUTANTS IN SURFACE
WATER
3 PERCENT OF A SUBSTANCE REMAINING AS A FUNCTION 23
OF THE NUMBER OF HALF-LIVES ELAPSED
4 EMPIRICAL RELATIONSHIP BETWEEN METAL PARTITION 31
COEFFICIENT (Kg) AND SUSPENDED SOLIDS
CONCENTRATION QSS)
5 CALCULATIONS OF DISSOLVED AND PARTICULATE 33
FRACTIONS OF SELECTED PRIORITY METALS IN
STREAMS AT SPECIFIED SOLID CONCENTRATIONS
6 COMPARISON OF PARTITION COEFFICIENT FOR 56
SEVERAL SUBSTANCES USED TO SCORE TOXICITY/
PERSISTENCE IN THE SURFACE WATER ROUTE OF
PROPOSED AND FINAL NPL SITES
7 CLASSIFICATION OF HAZARDOUS SUBSTANCES BY 67
THEIR HALF-LIVES—STREAMS /RIVERS I
8 CLASSIFICATION OF HAZARDOUS SUBSTANCES BY 78
THEIR HALF-LIVES—STREAMS/RIVERS II
9 THE DOMINANT PROCESS FOR SUBSTANCES WITH 82
HALF-LIFE EQUAL TO OR LESS THAN 1 DAY
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1.0 INTRODUCTION
1.1 Background
The Comprehensive Environmental Response, Compensation, and
Liability Act of 1980 (CERCLA) (PL 96-510) requires the President to
identify national priorities for remedial action among releases or
threatened releases of hazardous substances. These releases are to
be identified based on criteria promulgated in the National
Contingency Plan (NCP). On July 16, 1982, EPA promulgated the
Hazard Ranking System (HRS) as Appendix A to the NCP (40 CFR 300;
47 FR 31180). The HRS comprises the criteria required under CERCLA
and is used by EPA to estimate the relative potential hazard posed
by releases or threatened releases of hazardous substances.
The HRS is a means for applying uniform technical judgment
regarding the potential hazards presented by a release relative to
other releases. The HRS is used in identifying releases as national
priorities for further investigation and possible remedial action by
assigning numerical values (according to prescribed guidelines) to
factors that characterize the potential of any given release to
cause harm. The values are manipulated mathematically to yield a
single score that is designed to indicate the potential hazard posed
by each release relative to other releases. This score is one of
the criteria used by EPA in determining whether the release should
be placed on the National Priorities List (NPL).
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During the original NCP rulemaking process and the subsequent
application of the HRS to specific releases, a number of technical
issues have been raised regarding the HRS. These issues concern the
desire for modifications to the HRS to further improve its capability to
estimate the relative potential hazard of releases. The issues include:
• Review of other existing ranking systems suitable for ranking
hazardous waste sites for the NPL.
• Feasibility of considering ground water flow direction and
distance, as well as defining "aquifer of concern," in
determining potentially affected targets.
• Development of a human food chain exposure evaluation
methodology.
• Development of a potential for air release factor category in
the HRS air pathway.
• Review of the adequacy of the target distance specified in the
air pathway.
• Feasibility of considering the accumulation of hazardous
substances in indoor environments.
• Feasibility of developing factors to account for environmental
attenuation of hazardous substances in ground and surface water.
• Feasibility of developing a more discriminating toxicity factor.
• Refinement of the definition of "significance" as it relates to
observed releases.
• Suitability of the current HRS default value for an unknown
waste quantity.
• Feasibility of determining and using hazardous substance
concentration data.
• Feasibility of evaluating waste quantity on a hazardous
constituent basis.
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• Review of the adequacy of the target distance specified in
the surface water pathway.
• Development of a sensitive environment evaluation
methodology.
• Feasibility of revising the containment factors to increase
discrimination among facilities.
• Review of the potential for future changes in laboratory
detection limits to affect the types of sites considered for
the NPL.
Each technical issue is the subject of one or more separate but
related reports. These reports, although providing background,
analysis, conclusions and recommendations regarding the technical
issue, will not directly affect the HRS. Rather, these reports will
be used by an EPA working group that will assess and integrate the
results and prepare recommendations to EPA management regarding
future changes to the HRS. Any changes will then be proposed in
Federal notice and comment rulemaking as formal changes to the NCP.
The following section describes the specific issue that is the
subject of this report.
1.2 Issue Description
The issue addressed in this report is the feasibility of
developing factors to account for environmental attenuation of
hazardous substances in surface water. Environmental attenuation is
used here to refer to the loss of substances from a medium of
concern through physical, biological and chemical processes.
Dilution may be an important physical mechanism for contaminant
attenuation, but it is not considered in this study.
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Persistence is used in the HRS to reflect the resistance of
hazardous substances to environmental attenuation while moving from
the release location to a target within a specified distance. In the
current HRS, persistence is based only on the biodegradability of
substances. Each substance is given an integer score from 0 to 3
using a look-up table on which nonpersistent substances are assigned a
value of 0, moderately persistent substances are assigned a value of 1
or 2, and highly persistent substances are assigned a value of 3. For
substances not in the table, the persistence ranking value is assigned
as follows:
Substance Assigned Value
Easily biodegradable compounds 0
Straight chain hydrocarbons 1
Substituted and other ring compounds 2
Metals, polycyclic compounds and
halogenated hydrocarbons 3
EPA has received public comments during both the National
Contingency Plan (NCP) and National Priorities List (NPL) rulemakings
that question the number of loss processes considered in the current
HRS persistence ranking method. These comments indicate that, while
biodegradation is an important mechanism affecting persistence of
chemicals in the aquatic environment, it is not necessarily the most
important attenuation mechanism for all hazardous substances.
Commenters, therefore, suggested that other physiochemical mechanisms
should be considered in rating persistence.
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In response to these comments, EPA is evaluating the
feasibility of developing factors to account for environmental
attenuation of hazardous substances in ground and surface water.
This report is a part of that effort.
The major attenuation mechanisms for any substance depend not
only on its chemical characteristics, but on the environment in which
it is found. For example, photolysis (i.e., a reaction caused by
absorption of sunlight) has been identified as an important attenu-
ation mechanism for several photoreactive compounds in surface water
(Zepp et al., 1984), but it is not likely an attenuation mechanism
in ground water. Similarly, the contribution of volatilization to
removal of pollutants in ground water is considerably smaller than
that in surface water (Zoeteman et al., 1980). Because the
mechanisms affecting attenuation in ground water and surface water
may be quite different, it is appropriate that these environments be
examined separately. This study focuses on the surface water
environment. The attenuation of hazardous substances in the ground
water environment is addressed in a companion study by Sayala (1987).
1.3 Objectives of the Study
The objectives of this study are:
• To identify the joint effect of several important processes
on the fate of hazardous substances in surface water.
• To evaluate the feasibility of incorporating these processes
in the HRS.
• To propose alternative persistence ranking schemes for the
surface water pathway.
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1.4 Scope of Work
Persistence of hazardous substances in the current HRS is
discussed in relation to the type of surface water environment in
which the hazardous substance travels: either streams and rivers or
lakes and reservoirs. Since the targets evaluated in the HRS surface
water pathway are limited to those within a target distance limit,
persistence is also evaluated over a target distance limit, considering
both transfer and transformation processes.
This study evaluates the persistence of hazardous substances in
the surface water environment by considering several physiochemical
processes. Their processes include five decay processes (biodegrad-
ation, photolysis, hydrolysis, free-radical oxidation, and
volatilization) and one equilibrium process (sorption). The paper
also addresses the combined effect of various processes on attenuation.
1.5 Approach
In order to consistently assess the contribution of each process
considered, quantitative information on each of the processes is
required. Thus, the feasibility of accounting for all these environ-
mental attenuation mechanisms in the HRS depends on the availability
of quantitative information such as rate constants (or half-lives) for
decay processes and partition coefficients for sorption. Existing
ranking systems were examined to determine whether an existing
mechanism could be adopted. None of these systems, however, contained
the required data as discussed below.
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To obtain the necessary quantitative information, the
literature was searched for half-lives (e.g., biodegradation half-
life, volatilization half-life) of hazardous substances in the
surface water environment and for partition coefficients of these
hazardous substances. Data on half-lives and partition coefficients
were found to be available for many hazardous substances. For other
hazardous substances these data may be estimated (e.g., see
Appendix G). Therefore, it was considered feasible to use such
quantitative information for the screening purposes of the HRS.
Steady-state models were then used to estimate the effects of
the five decay processes and sorption on hazardous substances in
surface water. For streams and rivers, the spatial variation of
cross-sectionally averaged substance concentration was described by
a one-dimensional (i.e., cross-sectionally integrated) mass balance
equation. Lakes and reservoirs were described as idealized fully-
mixed tank reactors. The solutions of these steady state models
allow the concentration resulting from the combined effect of all
six processes to be easily estimated.
Based on the results of these calculations, two alternative
methods for assigning persistence ratings to substances in the HRS
are proposed. In both methods, the persistence value assigned to a
substance depends on the expected reduction in total concentration
(i.e., dissolved and particulate) of the substance over the target
distance limit. The higher the expected reduction, the lower the
relative ranking value assigned to the hazardous substance.
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1.6 Review of Persistence Factors in Other Ranking Systems
The following 11 systems were identified for review of treatment
of persistence (see Appendix A for more detail about these systems):
• JRB Methodology
• HARM
• HARM II
• CSR
• S.P.A.C.E. for Health
• ADL
• SAS
• PERCO
• Dames and Moore Methodology
• Action Alert System
• RAPS
The last 2 systems (Action Alert System and RAPS) do not consider
persistence explicitly. Rather, they include methodologies for
estimating the effect of environmental attenuation on the concen-
tration of hazardous substances. Nonetheless, it is informative to
compare the loss processes considered in these 2 systems with the
processes considered in the current HRS.
The review of these systems focused on how the persistence
factors are used in the various systems and how persistence is
defined and evaluated. When more than one migration pathway is
considered in a system, the review focused only on the surface water
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pathway. The review findings are presented in Appendix A and are
summarized in Table 1.
Despite the variation in the value assigned to each of the four
persistence ranks, seven systems (JRB Methodology, HARM, HARM II,
GSR, S.P.A.C.E. for Health, ADL, Dames and Moore Methodology) use the
same criteria as those in the current HRS to evaluate persistence of
hazardous substances. That is, all seven systems define persistence
in terms of the biodegradability of the substance. Qualitative
guidelines are used for ranking hazardous substances in each system.
PERCO modifies the HRS persistence ranking criteria to give
higher persistence ratings than the other systems. This modification
was made because of the recognition that even relatively biodegradable
substances may require days to disappear from the environment.
Consequently, areas located within several miles downstream of a
waste site may not benefit from potential biodegradation.
Three systems (SAS, AAS, RAPS) require quantitative information,
such as half-life or decay/loss rate. SAS considers a substance as
persistent if it has an environmental half-life longer than six
months. The AAS requires that the overall loss rate of a substance
be estimated as the sum of the individual loss rates due to
hydrolysis, photolysis, free-radical oxidation and volatilization.
RAPS also uses a decay rate in estimating the environmental
concentration of the substance. However, there is no elaboration in
the RAPS documentation on the types of processes which have been
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TABLE 1
SUMMARY OF PERSISTENCE FACTORS IN OTHER RANKING SYSTEMS
System
JRB Methodology
HARM
HARM II
GSR
S.P.A.C.E. for
Health
ADL Methodology
Dames and Moore
Loss Process
Considered
HRS1
HRS
HRS
HRS
HRS
HRS
HRS
Criteria for
Ranking Persistence
HRS1
HRS
HRS
HRS
HRS
HRS
HRS
Look-up
Table
HRS1
NA
NA
NA
HRS
HRS
NA
Methodology
PERCO
Biodegradation
SAS
NA2
Action Alert
System
RAPS
Photolysis,
volatilization,
hydrolysis, free-
radical oxidation
Not explicity
specified
Easily biodegradable
compounds and straight
straight chain
hydrocarbons
(Moderately Persistent)
Substituted and other
ring compounds, metals
polycyclic compounds
and halogenated
hydrocarbons (Highly
Persistent)
Persistent, if half-life
greater than 6 months
Nonpersistentj if half-
life equal to or less
than 6 months
NA
NA
NA
NA
NA
NA
NA
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TABLE 1 (Concluded)
Footnotes
1-Same processes or criteria considered as the current HRS; that is,
only biodegradation is considered and substances are classified into
four ranks according to the following criteria:
Criteria Rank*
Easily biodegradable compounds Nonpersistent
Straight chain hydrocarbons Low persistent
Substituted and other ring compounds Moderately persistent
Metals, polycyclic compounds and Highly persistent
halogenated hydrocarbons
*The numerical value assigned may be different in different
systems.
available or not applicable.
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considered. Since RAPS was developed specifically to address
radioactive waste sites, decay may refer only to radioactive decay.
None of the systems reviewed provide an improved methodology
readily adaptable for use in the HRS.
1.7 Organization of the Report
This report is divided into five sections. Section 2 is an
overview of the several important transfer and transformation
processes which may act upon a hazardous substance in a typical
surface water environment. It illustrates the need to consider loss
processes in addition to biodegradation. It also describes the
functional relationship between the concentration of a substance and
the various processes identified. These functional relationships
serve as the building blocks for models introduced in Section 3.
Section 3 describes the models used to derive the variation of
the concentration of a substance over the target distance limit.
The models include all the important processes which have been
identified in Section 2.
Section 4 describes two alternative persistence ranking methods
which may be used in place of the method currently used in the HRS.
Both alternatives are based on modeling results obtained in
Section 3. However, the alternatives differ in that Alternative II
does not consider sorption and the subsequent settling loss while
Alternative I does.
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Section 5 compares the two proposed alternatives described in
Section 4. It also compares the two proposed alternatives with the
persistence ranking method currently employed in the HRS.
There are eight appendices in this report. Appendix A
summarizes the reviews of persistence factors in other site ranking
systems. Appendix B lists illustrative half-lives of substances in
streams and rivers. Appendix C lists illustrative half-lives of
hazardous substances in lakes and reservoirs. Appendix D lists the
logarithm of N-octanol-water partition coefficients. Appendix E
explains the rationale for selecting the method of estimating
partition coefficient of metals in natural environments. Appendix F
evaluates the range of 3-mile travel times in streams and rivers.
Appendix G outlines the methodology for calculating half-lives and
Appendix H is the glossary.
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2.0 MECHANISMS AFFECTING THE PERSISTENCE OF HAZARDOUS SUBSTANCES IN
A SURFACE WATER ENVIRONMENT
2.1 Introduction
As a substance enters a water body, in addition to being diluted and
transported by the flow, it may also be subjected to several transfer and
transformation processes, including: biodegradation, hydrolysis,
photolysis, volatilization, free-radical oxidation, and sorption.
Various studies have indicated that these processes are important in
affecting the aquatic fate of substances (e.g., Callahan et al., 1979;
Lyman et al., 1982; Mills et al., 1985; Delos et al., 1984; and Mabey
et al., 1982). Of these processes, only volatilization and sorption do
not change the composition of a substance, rather they move the substance
from water to other environmental media (i.e., air and sediment).
The relative importance of some of these processes in affecting the
aquatic fate of organic priority pollutants is summarized in Table 2.
In many instances, biodegradation has been identified as insignificant
in affecting the fate of substances. For example, for most of the
halogenated aliphatic hydrocarbons, biodegradation is either an
insignificant process or its importance is not known. For these
substances, volatilization is generally the prevailing fate-affecting
mechanism. This table clearly illustrates the limitations of the
present persistence ranking method and the need for a modification of
the HRS.
The remaining sections of this chapter present the formulations
commonly used to describe the effects of these six processes on the
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TABLE 2
RELATIVE IMPORTANCE OF PROCESSES AFFECTING THE FATE OF PRIORITY POLLUTANTS IN SURFACE WATER
Process
Compound
Sorption Volatilization Biodearadation Photolysis-Direct Hydrolysis
Pesticides
Acrolein
Aldrin
Chlordane
ODD
DDE
DDT
Dleldrin
Endosulfan and Endosulfan Sulfate
Endrln and Endrin Aldehyde
Heptachlor
Heptachlor Epoxlde
Hexachlorocyclohexane (o,P,6 isoraers)
-Hexachlorocyclohexane (Lindane)
Isophorone
TCDD
Toxaphene
PCBs and Related Compounds
Polychlorinated Biphenyls
2-Chloronaphthalene
Haloeenated Aliphatic Hydrocarbons
Chloromethane (methyl chloride)
Dichloromethane (methylene chloride)
Trichloromethane (chloroform)
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TABLE 2 (Continued)
Compound
Process
Sorptlon Volatilization Biodeeradation Photolysis-Direct Hydrolysis
Halogenated Aliphatic Hydrocarbons (Concluded)
Tetrachloromethane (carbon tetrachloride) ?
Chloroethane (ethyl chloride)
1,1-Dichloroethane (ethylidene dichloride)
1,2-Dichloroethane (ethylene dichloride)
1,1,1-Trichloroethane (methyl chloroform)
1,1.2-Trichloroethane ?
1,1,2,2-Tetrachloroethane ?
Hexachloroethan ?
Chloroethene (vinyl chloride) +
1,1-Dichloroethene (vinylidene chloride) ?
1,2-trans-Dichloroethene
Trichloroethene
Tetrachloroethene (perchloroethylene)
1,2-Dichloropropane ?
1,3-Dichloropropene ?
Hexachlorobutadiene +
Hexachlorocyclopentadiene +
Bromomethane (methyl bromide)
Bromodichloromethane ?
Dibromochloromethane ?
Tribromomethane (bromoform) ?
Dichlorodifluoromethane ?
Trichlorofluoromethane ?
Haloeenated Ethers
Bis(choromethyl) ether
Bis(2-chloroethyl) ether
Bis(2-chloroisopropyl) ether
2-Chloroethyl vinyl ether -
•H-
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TABLE 2 (Continued)
Process
Compound
Sorotion Volatilization Blodegradation Photolvsis-Dlrect Hydrolysis
oo
Halogenated Ethera (Concluded)
4-Chlorophenyl phenyl ether
4-Bromophenyl phenyl ether
Bls(2-chloroethoxy) methane
Monocvcllc Aromatlcs
Benzene
Chlorobenzene
1,2-Dlchlorobenzene (o-dlchlorobenzene)
l-3,Dlchlorobenzene (m-dichlorobenzene)
1,4-Dlchlorobenzene (p-dichlorobenzene)
1,2,4-Trichlorobenzene
Hezachlorobenzene
Ethylbenzene
Nitrobenzene
Toluene
2,4-Dinitrotoluene
2,6-Dinitrotoluene
Phenol
2-Chlorophenol
2,4-Dlchlorophenol
2,4,6-Trlchlorophenol
Pentachlorophenol
2-Rltrophenol
4-Hltrophenol
2,4-Dinitrophenol
2,4-Dlmethylphenol (2,4-xylenol)
B-chloro-m-cresol
4,6-Dlnltro-o-cresol
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TABLE 2 (Continued)
Compound
Process
Sorption Volatilization Biodeeradation Photolysis-Direct Hydrolysis
Phthalate Esters
Dimethyl phthalate
Diethyl phthalate
Di-n-butyl phthalate
Di-n-octyl phthalate
Bis(2-ethylhexyl) phthalate
Butyl benzyl phthalate
Polycyclic Aromatic Hydrocarbons
Acenaphthene3
Acenaphthylene3
Fluorene3
Naphthalene
Anthracene
Fluoranthene3
Phenanthr ene3
Benzo(a)anthracene3
Benzo(b)fluoranthene3
Benzo(k)fluoranthene3
Chrysene3
Pyrene3
Benzo(ghi)perylene3
Benzo(a)pyrene
Dibenzo(a,h)anthracene3
Indeno(1,2,3-cd)pyrene3
Nitrosamines and Misc. Compounds
Dimethylnitrosamine
Diphenylni t rosamine
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TABLE 2 (Concluded)
Process
Compound Sorptlon Volatilization Biodegradatlon Photolysis-Direct—Hydrolysis
Nltrosamlnea and Misc. Compounds (Concluded)
Di-n-propylnitrosamine - - - ++
Benzidine + - ? -f
3,3^- Dichlorobenzidine -H- - - + ~
1,2-Dlphenylhydrazine (Hydrazobenzene) + - ? + -
Acrylonitrile - + 1 -
Source: Hills et al. (1985).
•fCould be an important fate process.
•f+Predominate fate determining process.
-Rot likely to be an important process.
?Importance of process uncertain or not known.
Ifiiodegradation is the only process known to transform polychlorinated bipenyls under environmental conditions, and
only the ligher compounds are measurably biodegraded. There is experimental evidence that the heavier polychlorinated
biphenyls (five chlorine atoms or more per molecule) can be photolyzed by ultraviolet light, but there are not data to
indicate that this process is operative in the environment.
2Based on information for 4-nitrophenol.
3Based on information for PAHs as a group. Little or no information for these compounds exists.
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fate of a substance in the aquatic environment. The decay processes
are generally expressed as kinetic processes; sorption is generally
described as an equilibrium process (Fiksel and Segal, 1982, and
Delos et al., 1984). The five decay processes are described
together in Section 2.2 and sorption is described in Section 2.3.
These formulations are used in Section 3 for modeling the combined
effect of all these processes on the fate of substances in the two
types of surface water.
2.2 Biodegradation, Hydrolysis, Photolysis, Free-Radical Oxidation,
and Volatilization
Biodegradation, hydrolysis, photolysis, free-radical oxidation,
and volatilization are generally regarded as irreversible loss
processes for hazardous substances (Delos et al., 1984). The loss
rates are often expressed in terms of first-order kinetics because
of the low concentrations of hazardous substances expected in the
environment (Mabey et al., 1982). The first-order decay
coefficients for individual processes are additive; together they
form an aggregate decay coefficient:
Y = Y+Y+Y+Y+Y
B H P V 0
where "Y = Aggregate decay rate, in
VB - Biodegradation rate, in (time)"1
YJJ = Hydrolysis rate, in (time)"-*-
Yp = Photolysis rate, in (time)"1
Vv = Volatilization rate, in (time)"1
YQ = Free-radical oxidation rate, in (time)"-'-
This aggregate decay coefficient can be taken as a measure of
the persistence of the substance if sorption is not considered. An
21
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alternative way to describe the persistence of a hazardous substance
is to calculate its half-life (Mabey et al., 1982). The half-life
^1/2^ is tne Ien8tn of time required for the initial concentration
to be halved as a result of the decay loss. The half-life of a
hazardous substance is not dependent on the initial concentration for
the first order kinetics and is calculated by means of the following
equation:
t1/2 - (In 2)/Y (2)
or it may be calculated from the individual half-lives:
tl/2 " L : - _
(3)
(ti/2>V 0
where (ti/2)fl = Biodegradation half-life, defined as (In 2)/YB
(t1/2)n = Hydrolysis half-life, defined as (In 2)/YH
(ti/2)p = Photolysis half-life, defined as (In 2)/Yp
(t1/2)y = Volatilization half-life, defined as (In 2)/Vv
= Oxidation half-life, defined as (In 2)/V0
Table 3 shows the percent of substance remaining as a function
of the number of half-lives elapsed.
The feasibility of using half-life, as defined above, as a factor
in the HRS to account for environmental attenuation of substances
depends on the amount of data available. Fortunately, the half-life
may be estimated for a large number of hazardous substances, and it is
possible to rank the persistence of hazardous substances based on
their estimated half-lives. Appendices B and C present illustrations
of the estimated half-lives for over 250 substances in streams and
rivers and in lakes and reservoirs, taking into account biodegrad-
22
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TABLE 3
PERCENT OF A SUBSTANCE REMAINING AS A FUNCTION
OF THE NUMBER OF HALF-LIVES ELAPSED
Number of Half- Percent Substance
Lives Elapsed Remaining
0.11 90
1.0 50
2.0 25
3.3 10
4.3 5
6.6 1
10.0 0.1
13.0 0.01
23
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ation, hydrolysis, photolysis, volatilization, and free-radical
oxidation as appropriate. The only difference between the two
tables results from the fact that the volatilization half-life of a
substance in streams and rivers is different from that in lakes and
reservoirs (Lyman et al., 1982 and IGF, 1984).
Estimated decay rates (or half-lives) have in the past been
used for screening purposes (Fiksel and Segal, 1982; ICF, 1984; and
Mabey et al., 1982). This is especially useful for ranking the
persistence of substances in streams and rivers. As shown in
Section 4, because of the short expected travel time within the
target distance limit, the effects of these decay processes are
insignificant for substances with half-lives longer than one day.
Thus, there is no need to discriminate among substances with half-
lives longer than one day. It should be noted that in Appendices B
and C, a default value of 999 days is assigned to metals to represent
their persistent nature. In the case of metals, as well as other
elements, the only applicable decay process for estimating
persistence is volatilization because elements are conserved in
transformation reactions.
The majority of the information used to derive Appendices B
and C was collected from four sources: (1) "Exposure Profiles
Prepared in Support of RCRA Risk-Cost Analysis Model" (Environ,
1984); (2) "Screening Hydrolytic Reactivity of OSW Chemicals"
(Wolfe, 1985); (3) "Physio-Chemical Properties and Categorization of
24
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RCRA Wastes According to Volatility" (U.S. EPA, 1985); and
(4) "Technical Background Document to Support Rulemaking Pursuant to
CERCLA Section 102, Volumes 1, 2 and 3" (Environmental Monitoring
and Services, Inc., 1985).
The first source provides estimated half-lives for 58 organic
substances in the surface water environment. The second source gives
values for the Henry's constants of the substances; these were then
used to estimate the volatilization half-lives of the substances.
The third source addresses the hydrolytic reactivity of many
hazardous organic compounds listed in Appendix VIII of the RCRA
Subtitle C Hazardous Waste Regulations (40 CFR 261). The fourth
source provides a review of biodegradation, hydrolysis and
photolysis. Most of the information from this source is qualitative;
nonetheless, it is useful in identifying substances with expected
half-lives longer than five days.
2.3 Sorption
Surface water always carries with it some suspended load.
Suspended load refers to particles which are carried into the main
flow and lose contact with the river or lake bed. These particles
travel at a velocity almost equal to the flow velocity (Garde and
Ranga Raja, 1977). They interact with substances in water through
sorption and may influence the aqueous fate of those substances.
The fate of a sorbed substance is closely related to the fate of the
suspended solid material onto which it is sorbed. As the suspended
25
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solids settle out of the water column, they carry along with them
the sorbed substances. As they are re-entrained, they also carry
with them the sorbed substances.
In modeling the environmental fate of substances, sorption is
generally considered to be an equilibrium partition between the
water and suspended solids. The sorption potential of a substance
is often characterized by the partition coefficient (K ) of the
substance, which is defined as follows:
K'-t
where r is the sorption density, (i.e., the amount of substance
sorbed per unit mass of solid), and C, is the remaining substance
concentration in solution (i.e., the dissolved substance
concentration).
Sorption density is calculated by dividing the sorbed
particulate substance concentration (C ) by the suspended solid
concentration (SS). Therefore, the partition coefficient is also
expressed as:
K _ Particulate substance concentration/(SS)
Dissolved substance concentration
Since the interest of this study is to estimate the ratio
between the particulate and dissolved substance concentrations,
equation (5) is rearranged to:
Particulate substance concentration _£ = _ (GO)
Dissolved substance concentration C, p
26
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Alternately,
Dissolved substance Dissolved Total Substance
• x
concentration fraction concentration
that Is, C _ 1
K (SS) + 1 "
P
Particulate m Particulate Total substance
substance fraction concentration
concentration
r K (SS)
that is, p - R ?ss)+1 C (8)
P
It needs to be stressed here that the product of solid concen-
tration (SS) and partition coefficient (K ) defines the distribution
of a substance between the dissolved phase and the particulate phase.
3
Thus, a partition coefficient of 10 I/kg does not indicate the
relation of the particulate substance concentration to the dissolved
substance concentration. Rather the value of 10 I/kg would have to
be multiplied by the solid concentration (e.g., 200 mg/1 or 2 x 10
kg/1) to obtain a ratio of 0.2. In fact, particulate substance
concentrations range from 0.02 to 0.5 of the dissolved substance
concentrations in typical U.S. streams and rivers with suspended
solids ranging from 20 to 500 mg/1 (Britton et al., 1983).
The effect of sorption is much less in surface water than in
ground water. In ground water the major interacting solid phase is
the soil or rock matrix, the concentration of which far exceeds the
suspended solids concentrations typically encountered in surface
waters. Moreover, since the suspended solids travel at virtually
27
-------
the same velocity as the surface water flow, sorption would not
affect the total chemical concentration in surface waters until
there is a net loss of the particulate substance from the water
column due to sedimentation (Delos et al., 1984).
In the absence of actual data, a partition coefficient (K )
can be estimated using the methods described in Sections 2.3.1 and
2.3.2, incorporating basic environmental parameters and readily
available information on substances.
2.3.1 Organics
Most of the organic chemicals of concern under CERCLA are
hydrophobic, unionized compounds with only a limited degree of
polarity. The sorption of these chemicals on natural particles
(such as soils or suspended solids or sediments in streams) is
primarily driven by their hydrophobic nature and, therefore, is
dependent on the organic content of the particles (Karickhoff,
1984). For such cases, Karickhoff (1984) suggested that the
partition coefficient K be related empirically to the
octanol-water partition coefficient (K ) of the chemical and the
ow
organic carbon fraction of the particle (f ) as follows:
Kp = 0.41 x KOW x foc (9)
Measured values of K for organic chemicals have been found as low
-3 7
as 10 and as high as 10 , encompassing a range of ten orders of
magnitude. Several methods are available for calculating K from
the physical and chemical properties of the chemical. It is possible
28
-------
to estimate log K with an uncertainty of no more than 0.1 to
0.2 logarithm units (or from 25 to 50 percent of the K value)
(Lyman et al., 1982). Appendix D lists log K values for a
number of hazardous substances frequently encountered at NPL sites.
2.3.2 Metals
Many studies have been made to help assess, monitor and control
metals present in surface water. In these studies, metals are
generally reported in two fractions: the dissolved and the
particulate fractions. From the distribution of metals in the
dissolved and particulate fractions, Forstner and Wittmann (1979)
suggested that the alkali metals and alkaline earth metals, such as
sodium and calcium, are present predominantly in dissolved form;
iron and aluminum (and manganese under normal conditions in rivers)
are almost totally transported by means of solid particles; and
trace metals, such as cadmium and zinc distributions, are present in
both forms.
A more recent and extensive analysis of water-sediment
partition coefficients for priority pollutant metals was conducted
by HydroQual (Delos et al., 1984). Data were retrieved from the
water quality file STORET, a computer database maintained by EPA.
Overall, approximately 20,000 data points on nine priority metals
were available for analysis.
One objective of the HydroQual study was to calculate partition
coefficients for priority metals and, wherever possible, to relate
29
-------
the coefficients to appropriate environmental variables. HydroQual
concluded that:
• A pronounced relationship exists between partition
coefficients for the various priority metals and suspended
solids concentrations.
• No consistent correlation was found among partition
coefficients and other environmental factors, including pH,
alkalinity, temperature or BOD.
Since first noted by Kurbatov et al. (1951), pH has been
considered the primary variable that governs the extent of inorganic
adsorption (Schindler, 1981). Therefore, the absence of pH effect
observed in the HydroQual study calls for careful evaluation. An
analysis of this phenomenon is provided in Appendix E.
The regression results from the HydroQual study are summarized
in Table 4. In this table, the partition coefficient (K ) is
expressed as a function of suspended solids concentration (SS) as
follows:
K = a(SS)b (10)
The values of a and b differ with the type of metal and the
type of water body. This simple relationship allows the partition
coefficient of metals to be calculated from suspended solids
concentration.
Substituting equation (10) into equation (6), the following
relationship is obtained:
Particulate metal concentration 1+b (11)
Dissolved metal concentration
30
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TABLE 4
EMPIRICAL RELATIONSHIP BETWEEN METAL PARTITION COEFFICIENT (Kp)
AND SUSPENDED SOLIDS CONCENTRATION (SS)
Streams
Metal
Arsenic
Cadmium
Chromium
Copper
Lead
Mercury
Nickel
Silver3
Zinc
No. of
Records
1635
254
345
2722
1545
369
1394
—
2253
a
0.48xl06
4.00xl06
3.36X106
1. 04x10 6
0.31xl06
2.91xl06
0.49xl06
—
1.25xl06
b1
-0.7286
-1.1307
-0.9304
-0.7436
-0.1856
-1.1356
-0.5719
—
-0.7038
2
-0.993
-0.998
-0.914
-0.994
-0.350
-0.990
-0.974
—
-0.995
No. of
Records
1
296
211
577
411
169
285
—
914
Lakes
a
3.52X106
2.17X106
2.85xl06
2.04X106
1.97xl06
2.21xl06
—
3.34xl06
b1
—
-0.9246
-0.2662
-0.9000
-0.5337
-1.1718
-0.7578
—
-0.6788
2
—
-0.993
-0.818
-0.955
-0.965
-0.962
-0.970
—
-0.849
!KP = a(SS)b, where Kp is in the units of liter Kg/SS is in the unit of ing/liter.
^Correlation coefficient.
^Insufficient data to perform regression.
Source: Delos et al., 1984.
-------
Since b is negative for all metals studied, equation (11) suggests
that the distribution of metals in the particulate and dissolved
phases may become less dependent on the concentration of suspended
solids. This is especially true for cadmium (b = -1.13), chromium
(b = -0.93), and mercury (b = -1.14). For these three metals, the
ratio of particulate metal concentration to dissolved metal
concentration almost becomes independent of suspended solids
concentration.
Table 5 presents calculated values of the partition coefficient
and dissolved and particulate fractions of selected priority metals
in streams and rivers at several specified suspended solids
concentrations. The partition coefficient decreases with an
increase of solids concentration for all metals listed. However,
the distribution of metals between the dissolved and particulate
phases is less dependent on the solids concentration, particularly
for cadmium, chromium and mercury. Over a range of 1 to 500 mg/1
suspended solids concentration, the particulate fractions of cadmium,
chromium and mercury differ by less than 20 percent and for all
practical purposes, it may be assumed that the particulate/dissolved
distributions of the three metals are insensitive to suspended solids
concentration in this range.
2.4 Effect of Sorption on Other Transformation Processes
Substances sorbed on a solid enter a microenvironment, which is
governed by the surface characteristics of the solid. This
32
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TABLE 5
CALCULATIONS OF DISSOLVED AND PARTICULATE FRACTIONS OF SELECTED
PRIORITY METALS IN STREAMS AT SPECIFIED SOLID CONCENTRATIONS
Arsenic
Cadmium
Chromium
Copper
ss1
mg/1
1
50
200
500
1
50
200
500
1
50
200
500
1
50
200
500
K2
1/ig
4. 8x10 5
2.8xl04
l.OxlO4
5.2xl03
4.0xl06
4.8xl04
l.OxlO4
3.6xl03
3.36xl06
8.8xl04
2.4xl04
l.OxlO4
1.04xl06
5.7xl04
2.0xl04
l.OxlO4
3
Dissolved
Fraction
0.68
0.42
0.33
0.28
0.20
0.29
0.33
0.36
0.23
0.18
0.17
0.16
0.49
0.26
0.20
0.16
A
Particulate
Fraction
0.32
0.58
0.67
0.72
0.80
0.71
0.67
0.64
0.77
0.82
0.83
0.84
0.51
0.74
0.80
0.84
33
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TABLE 5 (Concluded)
ss1
mg/1
Lead 1
50
200
500
Mercury 1
50
200
500
Nickel 1
50
200
500
Zinc 1
50
200
500
K2
l/ig
3.1xl05
l.SxlO5
1.2xl05
9.8xl04
2.91xl06
3.4xl04
7. 1x10 3
2. 5x10 3
4.9xl05
5.2xl04
2.4xl04
1.4xl04
1.25xl06
S.OxlO4
3.0xl04
1.6xl04
Dissolved
Fraction
0.76
0.12
0.04
0.02
0.26
0.37
0.41
0.44
0.67
0.28
0.17
0.12
0.40
0.20
0.14
0.11
4
Particulate
Fraction
0.24
0.88
0.96
0.98
0.74
0.63
0.59
0.56
0.33
0.72
0.83
0.88
0.60
0.80
0.86
0.89
^-Suspended solids concentration in stream.
2Partition coefficient, calculated from regression equations in
Table 4.
3Calculated as [Kp (SS) + I]'1.
4Calculated as (1.0 - dissolved fraction).
34
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microenvironment differs from the bulk aquatic environment. The
sorbed substance, therefore, is likely to have reaction rates
different from those of the dissolved substance, but it is not
always possible to estimate the extent or direction of these
differences.
Baughman et al. (1980) showed that the dissolved fraction of
the compounds studied was available for biodegradation while the
particulate fraction was not. On the contrary, Mills et al. (1985)
suggested that, since bacteria grow readily on the surface of solid
particles, the presence of sediment can increase the rates of
microbial metabolism. The volatilization rate is a function of the
dissolved substance concentration; therefore, the presence of
particulate material slows down volatilization by reducing the
concentration of the dissolved chemical (Mackay and Shiu, 1984).
Neutral hydrolysis rates for several organic chemicals were found to
be the same for both the dissolved and the sorbed chemical, but
alkaline hydrolysis rates were found to be slower for the sorbed
chemicals (Macalady and Wolfe, 1984). Zepp and Scholtzhauer (1981)
reported that the photolysis rates of DDE sorbed on aqueous
suspension of well-characterized sediments are affected by the
length of time that the DDE is sorbed on the sediments. The DDE is
sorbed onto two types of sediment sites—sites at which DDE reacts
at a higher rate than when it is dissolved in water; and other sites
at which the chemical is nonreactive. Thus, the overall photolysis
35
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rate becomes limited by diffusion of DDE from the unreactive to the
reactive sites.
These difficulties indicate that it is not possible to
generalize as to the effect of sorption on other transformation
processes. A conservative approach is taken in this report which
assumes zero decay by means of biodegradation, hydrolysis,
volatilization, free radical-oxidation, or photolysis for the sorbed
substances.
36
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3.0 MODELS OF SUBSTANCE FATE FOR IDEALIZED WATER BODIES
3.1 Overview
Simple fete and transport models are used in this section to
illustrate the effect of the various loss processes on the persistence
of a substance in surface water.
Persistence of a substance may be defined as the capability of a
substance to resist a reduction of its concentration despite the
several loss* processes acting upon it by the environment. Therefore,
the persistence of a substance, if evaluated over a specified distance,
is related to the reduction of the substance concentration over that
distance. In this presentation, a logical choice for this distance of
interest is the target distance limit in the surface water pathway
which is currently defined as 3 stream miles (or 1 mile in static
surface water, such as a lake) downstream of the probable point of
entry to surface water or downstream of the furthest measurement
supporting an observed release (40 CFR 300, 47 FR 31180, July 16,
1982). As a result, the models described in this section are formu-
lated with the objective of estimating the change of a substance
concentration over those distances. The loss processes incorporated
in the models are:
*Dilution is not considered a loss process in this report.
37
-------
• The decay processes—biodegradation, hydrolysis, photolysis,
volatilization and free-radical oxidation.
• The sedimentation loss of the sorbed chemical.*
In the HRS, surface water is classified into two broad categories:
streams/rivers and lakes/reservoirs. The primary difference in the
hydrodynamic properties of these two classes of water bodies is that
streams and rivers tend to be advection dominated, whereas lakes and
reservoirs tend to be dispersion dominated. Consequently, a one-dimen-
sional model** (with the axis taken along the direction of the flow in
stream) is often used to describe streams and rivers and a fully mixed
system is often used to describe lakes and reservoirs (Thomann, 1972).
3.2 Streams and Rivers
The model described in this section is the standard one-dimen-
sional, steady-state model (Thomann, 1972). It predicts the steady-
state concentration (cross-sectionally averaged) profile along the
river reach downstream of the substance entry point.
*For purposes of developing options, this paper treats sorption
followed by settling as a loss process. However, hazardous
substances which are removed from the water column by sorption and
sedimentation may still be available to ecosystems through uptake
by benthic organisms. Also, the hazardous substances may be
available to human populations and ecosystems through resuspenslon.
Consequently, EPA may not wish to treat sorption followed by
settling as a loss process. Options presented in Chapter 4 allow
for both possibilities.
**A one-dimensional model does not describe the variation of concentr-
ation over the cross-section of the stream and river. Such a model
is applicable in describing the variation of a concentration which is
averaged over the cross-section, or in regions where the substance is
fully mixed across the cross section such as in region downstream of
the mixing zone.
38
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3.2.1 General Model, Considering Both Settling and Decay
Figure 1 is a schematic diagram of the model. The total
substance concentration (C) in the water column consists of two
parts — the dissolved substance concentration (C,) and the
particulate substance concentration (C ). The dissolved and the
particulate substances are assumed to be in equilibrium partition as
previously described in equations (7) and (8) which are as follows:
d i + K
P
(7)
v"
K (SS)
C (8)
P l + K
The dissolved substance decays at a rate which represents the sum
of all the decay processes described in Section 2.2. Since this
study assumes no decay loss for particulate substances (Section 2.4),
the particulate substance is considered to be lost through settling
at a rate g, which is the same as the settling loss rate of
suspended solids (SS). Both Y and g are in units of (time)
Assuming that the longitudinal dispersion is negligible (Fischer
et al., 1979), the equations which describe the variation of the
substance and suspended solids concentrations along the river reach
during the steady-state are as follows:
- ai • -* CP -
u d - -g (SS) (13)
where: x ** Distance downstream of the entry point of the chemical.
u = Mean flow velocity.
39
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SUBSTANCE:
Decay Loss Rate (r)
Total Substance Concentration (C)
Dissolved
Substance
Concentration
(Cd)
Equilibrium
Partition
Paniculate
Substance
Concentration
(Cp)
C = Cd +
Sedimentation
Rate
(9)
SUSPENDED SOLIDS:
Sedimentation
Rate
(g)
FIGURE 1
A SCHEMATIC DIAGRAM SHOWING THE IMPORTANT PROCESSES
AFFECTING FATE OF SUBSTANCES IN A SURFACE WATER BODY
40
-------
Equation (12) may be solved using the solution for SS, as well as
equations (7) and (8). The solution for SS is:
SS . ~8 u (14)
SSo
and the solution for C is:
-V* -8
C u 1 + e U
e
with a = Kp-SS0
where Co = Total substance concentration at the entry point of
the substance (i.e., at x = 0).
SS0 = Suspended solids concentration at the entry point of
the substance (i.e., at x = 0).
x = Travel time; the time required by substance to travel
u from the entry point to a point at x distance downstream.
The sedimentation rate g, needed for the calculation of C,
generally is not known beforehand, but is calibrated with field data
on suspended solids concentration using equation (14). In the
remainder of this report, when information on sedimentation rate is
indicated as necessary, the measurement of suspended solids
concentration needs to be made at more than one location so as to be
a representative measurement.
3.2.2 Model With Decay Only
In some instances , sedimentation is not a significant loss
process either because the substance of interest has little sorption
potential, because limited sedimentation has occurred between the
*In the case of metals, whose Kp has been found to be a function of
SS, a different solution is needed and is presented in Section 3.2.4.
41
-------
two locations at which suspended solids concentrations have been
measured, or because of the reasons indicated in Section 3.1. The
solution for these cases may be obtained by letting g approach zero
in equation (15). A simpler way to find the solution is to
reformulate the governing equation for this simplified case by
dropping the sedimentation loss term from equation (12):
u ^2 = _YC. (16)
dx d
There is no need to write an equation for SS because, with no
settling SS remains constant with distance. Therefore, equation (16)
is solved by substituting equation (7) into it and the solution for
C becomes:
r ~YfH £
£- = e d U (17)
o
where f as)
42
-------
3.2.4 Model With Settling Only, With Partition Coefficient as
a Function of Suspended Solids Concentration
This special case of the possible decay processes illustrates
the effect of very long persistence for selected substances. In
particular, this case shows how metals, which are of interest due to
their potential hazard, might behave.
The partition coefficients for metals have been shown to be a
function of suspended solids concentration (Section 2.3.2):
K = a(SS)b (10)
P
where a and b are regression coefficients given in Table 4. The
relationship between the dissolved and the particulate metal
concentrations is :
C 1 + b
7^ = a(SS) (11)
Cd
or we may write:
1 + a(SS)1 + b
The equation which describes the change of SS remains the same:
u d ^J/ = -g (SS) (13)
The governing equation for C is simplified from equation (12) by
dropping the decay loss term:
U ll = ~8 Cp (20)
This equation may be solved by using the solution for SS that is,
equation (14) and by using equation (19). The solution for C is:
43
-------
- - a * Pe ,
where p - a(SSo)1+b
3.3 Lakes and Reservoirs
The model is a standard steady-state model and it considers a
lake as a fully raised tank reactor with constant inflow and
outflow. That is, there is no concentration gradient in the lake
and the outflow concentration is the same as the concentration in
the lake. It describes the steady-state (lake concentration)
averaged over the lake volume of interest* in relation to the
external input. Figure 2 is the definition sketch of the idealized
lake or reservoir under this model assuming contaminants are brought
into the lake at concentration C. by the inflow. As in the case
in streams and rivers, the total substance concentration (C) in the
water column of lakes and reservoirs consists of two parts—the
dissolved substance concentration (C,) and the particulate
substance concentration (C ). The dissolved and the particulate
substances are assumed to be in equilibrium partition as described
in equations (7) and (8):
C.
+ K (SS)
P
K (SS)
r = P r
p 1 + K (SS) L
*Refers to the lake volume within the specified target distance limit.
44
-------
Inflow
(Concentration Cj)
Mixing
Decay Loss Rate (r)
\ Total Substance Concentration (C)
Dissolved
Substance
(Cd)
Equilibrium
Partition
C = Cd + Cp
Partk
Subs
(C
;ulate
tance
ntration
p)
Outflow
(Concentration C)
Sedimentation
Rate
(9)
FIGURE 2
A SCHEMATIC DIAGRAM SHOWING THE IMPORTANT PROCESS
AFFECTING FATE OF SUBSTANCES IN AN IDEALIZED LAKE OR RESERVOIR
45
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The dissolved substance decays at a rate which represents the
sum of all the decay processes described in Section 2.2. Since this
study assumes no decay loss for particulate substances (Section 2.4),
the particulate substance is considered to be lost through settling
at a rate g, which is the same settling loss rate of suspended
solids (SS). Both V and g are in units of (time) .
At steady state, the relationships between the inflow concen-
trations of substance (C.) and suspended solids (SS.) and the
volume-averaged concentration of substance (C) and suspended solids
(SS) in lakes and reservoirs are described by the following equations:
0 = Q (C -C) -g C - C. (22)
V i P d
0 = Q (SS -SS) -g (SS) (23)
V i
where: Cj_ = Inflow concentration.
C = Average substance concentration in the volume of water.
V = Volume of the water defined from the inflow location to
the target distance limit. During the stratification
period, this only refers to the volume which lies above
the thermocline.
Q = Flow rate.
SS^ = Inflow suspended solids concentration.
SS = Average suspended solids concentration in the volume of
the water.
The solution for C is:
C_ = 1 (24)
C± 1 + fpg 4- fdY) T
and the solution for SS is:
SS - 1 (25)
1 + gT
46
-------
where T is the hydraulic retention time, defined as V/Q, f is the
particulate fraction of the substance, f, is the dissolved fraction of
the substance. The values of f and f, are calculated as follows:
P d
K (SS)
fp = Kp ?SS> + 1 (26)
fd = K (SS) + 1 (26)
P
where K is partition coefficient which may be estimated using
equation (9) for nonpolarized organics, or estimated by using
equation (10) and coefficients in Table 4 for priority pollutant
metals.
If no settling takes place (i.e., g = 0), the solution for C is
simplified to:
C_ = 1 (28)
ci 1 + fd ^T
If no decay takes place (i.e., Y = 0), the solution for C is:
C_ = 1 (29)
C± 1 + f p gT
47
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4.0 ALTERNATIVES TO THE CURRENT HRS PERSISTENCE RANKING METHOD FOR
THE SURFACE WATER PATHWAY
4.1 Overview
This section describes two persistence ranking methods which
may be used as alternatives to the current HRS method. Both
alternatives are based on the expected reduction of the substance
concentration over the target distance limit.* The less the
reduction of concentration as a result of the loss processes
identified in Section 2, the greater the substance's persistence is
deemed to be and the higher the rating value assigned to it. The
first alternative considers the joint effect of sorption,
biodegradation, hydrolysis, photolysis, volatilization, and
free-radical oxidation. The kinetic information on the latter five
processes has been compiled in Appendices B and C. The settling
loss of substances through sorption, however, cannot be quantified
without site measurement. If EPA decides not to consider settling
as a loss process or if it is not practical within CERCLA site
inspections to require additional site measurement to determine the
settling loss, a second alternative is proposed which ranks
substances according to only biodegradation, hydrolysis, photolysis,
*The target distance limit in the surface water pathway is defined as
3 stream miles (or 1 mile in static surface water, such as a lake)
downstream of the probable point of entry to surface water or down-
stream of the last measurement of an observed release in streams
or rivers.
49
-------
free-radical oxidation, and volatilization. In both alternatives,
the appropriate equations from Section 3 are used to calculate the
expected reduction in concentration of substances in both streams
and rivers and in lakes and reservoirs.
Four ranking categories are proposed for both alternatives.
These categories are as follows: "persistent," if the reduction in
concentration is less than 50 percent over the target distance
limit; "moderate," if the reduction in concentration is between
50 percent and 90 percent over the target distance limit; "low," if
the reduction in concentration is between 90 percent and 99.9 percent
over the target distance limit; "nonpersistent," if the reduction in
concentration is greater than 99.9 percent over the target distance
limit.
The two methodologies are described in the following sections
according to the type of water body and the type of substance of
interest. Whenever possible, a sensitivity analysis section is
provided to offer preliminary assessment of the relative importance
of some parameters.
4.2 Alternative I
This alternative considers the effects of both sorption and
decay processes. The procedure for ranking substances differs
according to the type of substance (metals vs. organics) and the
type of water body concerned (streams and rivers vs. lakes and
reservoirs).
50
-------
4.2.1 Streams and Rivers
The details of the proposed Alternative I ranking method are
shown in Figure 3.
4.2.1.1 Metals. In streams and rivers, if the substance of
concern is a metal, equation (21) is used to calculate C/C .
Based on the value of C/C , the metals are classified in one of
the four rank categories:
Rank Criteria
Persistent 0.5 < C/CO
Moderate 0.1 < C/C0 < 0.5
Low 0.001 < C/C0 < 0.1
Nonpersistent C/CO < 0.001
Five parameters are needed for the calculation: suspended
solids concentration at the beginning and the end of thte target
distance limit, travel time within the target distance limit, and
coefficients a and b for estimating the partition coefficient. The
travel time can be estimated from flow velocity.* In the absence of
an explicit measurement, a default value of 0.1 days is recommended,
which is a representative three-mile travel time in streams and
rivers (Appendix F). The values of a and b are given in Table 4.
The two suspended solid concentrations must be measured.
4.2.1.2 Organics. The expected concentration change is
calculated using equation (15), which considers the simultaneous
*Flow velocity varies with time. Choice of the period during which the
measurement is made should be based on the degree of conservativeness
intended.
51
-------
Streams/Rivers
Metals
Calculate C/C0 using Eq.(21)
Persistent; if C/GO> 0.5
Moderate; if 0.5> C/CQ> 0.1
Low; if 0.1 >C/C0> 0.001
Non-persistent; if 0.001 > C/C0
Organics
Calculate C/Q, using Eq.(15)
• Persistent; if C/Co> 0.5
• Moderate; if 0.5>C/CQ> 0.1
• Low; if 0.1>C/Co> 0.001
• Non-persistent; if 0.001 >C/C0
Parameters:
• Two suspended solids concentrations
within the target distance limit
• Travel time1
• Coefficients a, b^
Parameters:
• Two suspended solids concentrations
within the target distance limit
• Partition coefficients
• Half-life 4
* Travel time
• Organic carbon fraction of the
suspended solids
1 A value of 0.1 days is recommended based on the current MRS target distance limit (See Appendix F).
* Available in Table 4
^ Calculated as (0.41 x KQWX fow ); KQW values are available in Appendix D.
4 Calculated as 0.693/half-life; illustrations of the values of half-lives are available from Appendix B.
FIGURES
PERSISTENCE RANKING METHOD FOR SUBSTANCES
IN STREAMS AND RIVERS - ALTERNATIVE I
52
-------
effect of decay loss and sedimentation loss resulting from sorption.
An appropriate simplified equation [equation (17) or (18)] may be
used to replace equation (15), if either decay loss or sedimentation
loss dominates the fate of the substance.
The substance are classified into four rank categories according
to the same criteria used to classify metals:
Rank Criteria
Persistent 0.5 < C/CO
Moderate 0.1 < C/CO < 0.5
Low 0.001 < C/C0 < 0.1
Nonpersistent C/CO < 0.001
Six parameters are needed for the calculation: suspended solids
concentration at the beginning and the end of the target distance
limit, travel time within the target distance limit, decay loss rate,
octanol-water partition coefficient and organic carbon fraction of the
suspended solids. The last two parameters are used to estimate the
partition coefficient of organic substances by means of equation (9):
Kp = 0.41 x foc x KQW (9)
The values of K for a number of substances can be obtained
ow
from data in Appendix D. The decay loss rate can be estimated from
the half-life (t,/2) of th£ substance by:
Y _ 0.693 (30)
" ti/2
Illustrations of half-lives in streams and rivers are listed for more
than 250 substances in Appendix B. The travel time can be estimated
from measurement of flow velocity. In the absence of measurement, a
53
-------
value of 0.1 day is recommended, which is a representative three-
mile travel time in streams and rivers (Appendix F).
In addition to these data, the organic fraction of the suspended
solids and the two suspended solids concentrations must be measured
to evaluate either metals or organics. In comparison with the
metals, organic substances require one additional measurement—the
organic carbon fraction of the suspended solids. For both metals
and organics, these measurements are necessary in order to quantify
the effect of sorption.
4.2.1.3 Sensitivity Analysis
Decay Loss
Assuming 0.1 days of travel time, in the absence of settling
loss, a substance needs to have a half-life of less than 0.1 days to
be ranked other than persistent (e.g., moderate). Of the more than
250 chemicals listed in Appendix B, only 18 chemicals (approximately
7 percent) have a half-life of less than 0.1 days. Therefore, in
streams and rivers, the majority of substances are expected to be
ranked as persistent unless settling loss is significant enough to
affect their ranks.
Metals vs. Organics
With only a few exceptions, decay loss is negligible for
organic chemicals over the travel time assumed. Consequently, the
persistence rank of a substance, be it organic or metal, largely
depends on its sedimentation loss.
54
-------
At a given site, the sedimentation loss of a substance depends
on the partition coefficient of the substance. The greater the
partition coefficient, the greater the fraction present in
particulate form which may settle out. Metals, because of their
high partition coefficients (Table 6), are expected to be attenuated
more through sedimentation loss than organic substances.
Settling Loss With Regard to Geographic Location of the Site
A geographical distribution of the suspended solids concen-
tration is shown in Figure 4. On the east and west coast, the
suspended solids concentration is low—mostly in the range of 0 to
50 mg/1; thus, the effect of sorption may be insignificant for many
substances (see Sections 3.2 and 3.3). Many states in the Mountain
Region and quite a few states in the Central Region have much higher
suspended solid concentrations (200 mg/1 to above 500 mg/1). In
these states, the effect of sorption would be important. On the
other hand, it is likely that suspended solids in these regions are
mostly inorganic. If the hazardous substance of concern is organic,
then, despite the high suspended solids concentration, the low
organic content of the suspended solids may cause sorption to be
unimportant (see equation (9)).
For most of the organic chemicals, because of the negligible
decay loss expected over the travel times considered, the value of
C/C is estimated using equation (18):
o
55
-------
TABLE 6
COMPARISON OF PARTITION COEFFICIENT FOR SEVERAL SUBSTANCES
USED TO SCORE TOXICITY/PERSISTENCE IN THE SURFACE
WATER ROUTE OF PROPOSED AND FINAL NPL SITES
Substance Name
Site Frequency
Log K
Metals
Lead
Trichloromethane (chloroform)
Chromium
Arsenic
Cadmium
Mercury
Zinc
Copper
Nickel
143
80
67
55
44
31
18
13
5
5.0
1.0
4-6.5
3.7-5.7
3.6-6.6
3.4-6.5
4.2-6.1
4.0-6.0
4.1-5.7
Organics
Tetrachlorome thane (carbon
Pentachlorophenol
Benzene
Trichloroethylene (TCE)
Lindane
Phenol
Benzo-a-pyrene
Chlordane
tetra chloride)
23
31
13
18
10
8
11
9
1.8
4.0
1.6
1.4-2.0
2.0
0.5
4.0
2.0
^Number of sites at which the substance is reported present
according to the NPL technical data base as of November 2, 1986.
bOrganics: Calculated by means of equation (9) using the KQW
value from Appendix C and assuming foc to be 0.25
(which refers to suspended solids with high organic
content). Thus, the calculated partition coefficients
represent the high values of those may be expected in
the natural environment.
Metals: Taken from Table 5; that is, the estimated Kp values
over a range of suspended solids concentration from 1
500 mg/1.
to
56
-------
ea-
se—
§ 49-
o
t 47
< 42
CO
0 35-
o:
UJ
1 28 —
2 21-
14 —
7 —
0
01
Mean-947
Number of stations-328
Standard deviation-6101
^
^
|
1
^
^^Bti^^-^^
— 21
— 19
- 17
-15
13
- II
- 6
- 4
- 2
0
o
UJ
1 2 5 10 20 50 100200500 1
2 5 10 20 50 100 200 500
thousands
MEAN CONCENTRATION OF SUSPENDED SEDIMENT, IN MILLIGRAMS PER LITER
EXPLANATION
Concentration of suspended
sediment, in milligrams per liter
O
0-50
51-200
201-500
501-2000
2000-84,900
Stations monitoring
flow from the
Great Lakes
Water Resources
Region boundary
Accounting Unit
boundary
Source- Britton et at (1983). o 200 400 eoo KILOMETERS
FIGURE 4
MEAN CONCENTRATION OF SUSPENDED SEDIMENT AT NASQAN STATIONS DURING
1976 WATER YEAR. MAP AT BOTTOM IS CODED TO SHOW MEAN DATA FOR
STATIONS REPRESENTING FLOW FROM THE ACCOUNTING UNIT.
57
-------
~8 —
C_ _ 1 + ae U
C ~ 1 + a
o
where ct = Kp.(SSo)
The value of -gp represents the expected change of suspended solids
concentration over the target distance limit (see equation (14)).
In the limiting case where the value of a is much smaller than 1
(i.e., the particulate fraction is much less than 1, indicating that the
majority of the substance is present in a dissolved state), the value of
C/C approaches 1, and little settling loss is expected. Thus, the
suspended solids concentration itself may dictate the persistence of
some substances regardless of the change of the suspended solids
concentration between the two locations of interest. At a suspended
solids concentration of 20 mg/1 (typical of eastern regions), organic
3 7
substances with partition coefficients less than 10 * will be
persistent. At a suspended solids concentration of 500 mg/1, fewer
substances will be ranked as persistent (i.e., only substances with
2 3
partition coefficients less than 10 ' ). In the limiting case where
the value of a approaches 1 the persistence ranking of substances
depends on settling loss.
Moreover, the suspended solids concentration at a given site and
the detection limit of suspended solids automatically limit the maximum
quantifiable percent removal of suspended solids at that site (or the
lowest persistence rank possible for a substance according to its
sedimentation loss). This can be seen by assuming that the detection
58
-------
limit for suspended solids is about 4 mg/1 (U.S. EPA, 1979). If we
are interested in examining a site with a suspended solids
concentration of 20 mg/1, the maximum sorption loss detectable would
be 16 mg/1, or 80 percent. At this hypothetical site, no substance
would be ranked as being either "non per sis tent" or low persistent"
as a result of settling loss. Similarly, at a site with a higher
suspended solids concentration of 500 mg/1, the maximum detectable
sorption loss is about 99 percent, and using the methodology
outlined in Section 4.2.1, no substance would be ranked as
"non per sis tent" on the basis of settling loss.
4.2.2 Lakes and Reservoirs
4.2.2.1 The Ranking Method. The details of the proposed
ranking method to be used for substances in lakes and reservoirs are
shown in Figure 5 . Persistence ranking of substances in lakes and
reservoirs is based on the ratio between the expected concentration
at the target distance limit (C) and the inflow concentration (C ):
Rank Criterion
Persistent 0.5 <
Moderate 0.1 < C/C± < 0.5
Low 0.001 < C/Ci < 0.1
Nonpersistent C/C± < 0.001
The ratio C/C. is calculated using equation (20). Parameters
needed for the calculation are decay rate, settling loss rate,
dissolved (or particulate) fraction and hydraulic retention time.
Decay rate (Y) is calculated using the estimated substance half-life
(t. *«); illustrations of half-lives are presented in Appendix C:
59
-------
Lakes/Reservoirs
All Substances
Calculate C/Cj using Eq. (24)
Persistant; if C/C j> 0.5
Moderate; if 0.5> C/C j> 0.01
Low; if 0.01 > C/C j> 0.001
Non-persistent; if 0.001 > C/C j
Parameters:
• Hydraulic retention time
• Suspended solids concentration
• Partition coefficient^
• Decay rate 2
• Organic carbon fraction of the suspended solids
1 For organics, calculated as 0.41 x f oc x K^ ; 1^, is available in Appendix D.
For metals, calculated using equations in Table 4 and the suspended
solids concentration.
2 Calculated as 0.693/half-life; illustrations of half-lives are available from
Appendix C.
FIGURES
PERSISTENCE RANKING METHOD FOR SUBSTANCES
IN LAKES AND RESERVOIRS - ALTERNATIVE I
60
-------
Y = 0.693 (30)
tl/2
The settling loss rate can be estimated by means of equation (25) If
the concentrations of suspended solids are available. The estimation
of dissolved fraction is described in Section 2.3. Measurements
required include suspended solids concentrations in the inflow and
in the lake or reservoir (or outflow). If the substance of interest
is an organic substance, the measurement of the organic fraction of
the suspended solids is also required. Hydraulic retention time (T)
is calculated as follows:
T = I (31)
where Q is the flow rate and V is the volume of water between the
inflow location and the target distance limit. During stratification
periods, the volume is further restricted to the portion which lies
above the thermocline. Assuming this volume of water can be
estimated from the morphological information of the lake or
reservoir, flow rate is the parameter that requires measurement.
The total number of measurements is, therefore, four: the suspended
solids concentrations in the inflow and in the body of the lake or
reservoir, the organic carbon fraction of the suspended solids, and
the inflow rate.
61
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4.2.2.2 Sensitivity Analysis
Decay Loss
The time a substance spends over the target distance limit is
generally much longer in lakes and reservoirs than in streams and
rivers. Therefore, the longer reaction time available in lakes and
reservoirs enables decay processes to become more significant in
affecting the fate of substances. Assuming that the reaction time is
on the order of days to years, biodegradation and volatilization can
become significant decay processes in addition to hydrolysis and
photolysis (Appendix B).
Settling Loss
When a stream enters a lake or reservoir, the flow velocity
begins to decline and the suspended solids will begin to be deposited.
Thus, lakes and reservoirs may be considered as sediment traps.
Based on data collected from Tennessee Valley Authority
reservoirs, Churchill (Vanoni, 1975) relates the percentage of
incoming sediment passing through a reservoir to the sedimentation
index (SI) of the reservoir (Figure 6). Sedimentation index is
defined as the hydraulic retention time (in seconds) divided by the
mean flow velocity (in feet per second). The mean flow velocity is
calculated by dividing the flow rate (Q) by the average cross-
sectional area (A). Thus, SI is expressed as:
81 = Q7A
62
-------
100
60
40
20
10
Percentage of 4
incoming silt
passing
through
reservoir
1
0.6
0.4
0.2
0.1
10*
I I I I I I I
Curve for fine silt discharged
from an upstream reservoir
J I I I I I I L_LJ I I 1_LJ I I I I I I III
105 106 107 108
Sedimentation index of reservoir = period of retention/mean velocity
10s
Source: Vanoi, 1975.
FIGURE 6
CHURCHILL'S TRAP EFFICIENCY CURVE
63
-------
where A is the area. Expressing area as the ratio of volume to
length of the reservoir, equation (32) may be written as:
31 •
-------
The importance of decay reactions depends on the travel time between
two points. However, the time a substance spends over the target
distance limit is distinctively different for streams and rivers than
for lakes and reservoirs. In streams and rivers, the three-mile
travel time is expected to be much less than a day; whereas, in lakes
and reservoirs, the hydraulic retention time mostly falls in the range
of days to years. Thus, the difference in the time scales associated
with the two types of water bodies warrants different substance
classification schemes.
For streams and rivers, the substances are classified as follows:
Rank C/C Criterion
o_
Persistent 0.5 < C/CO 0.1 days < half-life
Moderate 0.1 < C/CO < 0.5 0.033 days < half-life < 0.1 days
Low 0.001 < C/C0 < 0.1 0.01 days < half-life < 0.033 days
Nonpersistent C/CO < 0.001 half-life <0.01 days
For lakes/reservoirs, the substances are classified as follows:
Rank C/C Criterion
Persistent 0.5 < C/C± 5 days < half-life
Moderate 0.1 < C/C± < 0.5 0.5 days < half-life < 5 days
Low 0.001 < C/Ci < 0.1 0.005 days < half-life < 0.5 days
Nonpersistent C/C± < 0.001 half-life < 0.005 days
In both cases, instead of using C/C and C/C. as the criteria
as in Alternative I, the explicit criterion used for the ranking is the
half-life of the substance. (This is to facilitate the classification
process. Illustrations of the expected half-lives of substances are
listed in Appendices B and C.) These half-life criteria have been
determined based on the corresponding C/C or C/C. value shown next
to them using the methodology described below.
65
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In the case of streams and rivers, C/C is calculated using the
following equation:
(34)
which is essentially equation (17) with the dissolved fraction (fj)
equal to 1. The value of — used for calculation is 0.1 days.
With each value of C/C , equation (34) is used to solve for and
half-life is calculated as ln2/Y.
In the case of lakes and reservoirs, C/C. is calculated using
the following equation:
VT
(35)
which is essentially equation (24) with the dissolved fraction (f, )
equal to 1 and the particulate fraction (fj) equal to 0. The value
of T is assumed to be one week (7 days). With each specified value
of C/C. , equation (35) is used to solve for Y and half-life is
calculated as ln2/Y.
Based on half-life values, rating tables may be prepared for
each type of water body with substances arranged according to their
ranks. Table 7 is an e ample of such a table indicating the ranks
of substances for streams and rivers using half-life values from
Appendix B. Appendix C contains illustrations of half-lives for
substances in lakes and reservoirs. Half-lives for all substances,
including those in Appendices B or C, need to be calculated using
the methodology presented in Appendix G.
66
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TABLE 7
CLASSIFICATION OF HAZARDOUS SUBSTANCES BY THEIR HALF-LIVES--STREAMS/RIVERS I*
Rank: Nonoerslstent (i.e.. half-life 5 0.01 day)
Acetyl chloride
Benzothrlchlorlde
Dlmethylcarbamoyl chloride
Methyl Isocyanate
Benzal chloride
Bls(chloromethyl) ether
Malelc anhydride
Phthalic anhydride
Rank: Low (I.e.. 0.033 day < half-life s 0.01 day)
1,2-Dlphenylhydrazlne
Benzene sulfonyl chloride
Chloromethyl methyl ether
Methyl chlorocarbonate
Toluene dllsocyanate
ON
Rank: Moderate (I.e.. 0.033 dav-< half-life < 0.1 day)
3,3'-Dlchlorobenzldine Dimethyl sulfate
Phenol
Rank: Persistent (I.e.. 0.1 day < half-life)
Acenaphthylene
Acetonltrlle
Acroleln
Acrylonitrile
Allyl Alcohol
Anthracene
Asbestos
Benzene
Benzidlne
Benzo(b)fluoranthene
Benzyl chloride
BIs-2-chloromethoxymethane
Bromopropyl phenyl ether (4-)
Acetaldehyde
Acetophenone
Acrylamlde
Aldrln
Ammonium Plcrate
Arsenic
Benzacrldlne (3,4-)
Benzene, 1,3.5-trinltro
Benzo(a)anthracene
Benzoqulnone (p-)
Bloxlrane (2,2'-)
Bromoacetone
Bruclne
Acetone
Acetylamlnofluorene (2-)
Acrylic acid
Aldlcarb
Aniline
Arsenic III oxide
Benzanthracene (1,2-)
Benzenethlol
Benzo(a)pyrene
Benzotrichlorlde
Bis (2-chloroisopropyl) ether
Bromemethane
Butanol (n-)
*Assuming a travel distance of 3 miles in 0.1 days.
-------
TABLE 7 (Continued)
Rank: Persistent (I.e.. 0.1 < half-Life') (Continued)
00
Butanone (2-)
Chlorambucil
Chloro-2,3-epoxypropane (1-)
ChloroacetaLdehyde
Chloroethene
ChlorophenoX (o-)
Chromium
Cresols
Cyclohexane
Cyclophosphamide
DDD
Di-n-octylphthalate
Dibenz(a.h)anthracene
Oibutylphthalate
Dichlorobenzene (1,4-)
Dichloroethane (1.2-)
Dichloroethylene (trans) (1,2-)
Dichlorophenol (2,6-)
Dieldrin
Diethylene dioxide (1,4-)
Diisopropyl fluorophosphate
Dlmethylamine
Dlmethylfuran
DimethyIphenol (2,4-)
Dinitrotoluene (2,4-)
Dloxane (1,4-)
Endosulfan
Ethyl acrylate
Ethyl methacrylate
Ethylene dibromide
Ethylenebis(dithiocarbamic acid)
Formaldehyde
Furfural
Hexachlorobenzene
Cadmium
Chlordane
Chloro-m-cresol (4-)
Chloroaniline (p-)
Chloroethyl vinyl ether (2-)
Chlorophenyl thiourea (l-o-)
Chrysene
Crotonaldehyde
Cyclohexanone
D (2,4-)
DDT
Di-n-propylnitrosamine
Dibenzopyrene (1,2,7,8-)
Dichloro-2-butene (1,4-)
Dichlorodifluoromethane
Dichloroethene
Dlchloromethane
Dichloropropane (1,2-)
Diepoxybutene (1,2,3,4-)
Diethyl phthalate
Dimethoate
Dimethylbenz[a]anthracene (7,12-)
DimethyInitrosamine
Dimethyl phthalate
Dinitrotoluene (2,6-)
Dipropylamine
Endrin
Ethyl carbamate
Ethyl methanesulfonate
Ethylene oxide
Fluoranthene
Formic acid
Glycldylaldehyde
Hexachlorobutadiene
Carbon tetrachlorlde
Chlomaphaz ine
Chloro-o-toluldlne (4-)
Chlorobenzene
Chloromethane
Chloropropionitrile (3-)
Copper
Curoene
Cyclohexyl-4,6-dinitrophenol (2-)
D salts and esters (2,4-)
Daunomyc in
Diallate
Dibromo-3-chloropropane (1,2-)
Dichlorobenzene (1,2-)
Dichloroethane (1,1-)
Dichloroethylene (cis) (1,2-)
Dichlorophenol (2,4-)
Dichloropropane (1,3-)
Diethyl-o-pyrazlnyl-
phosphorothioate (0.0)
Diethylstllbestrol
Dimethoxybenzidine (3,3-)
Dimethylbenzidine (3,3-)
Dimethylphenethylamine (a,or-)
Dinitro-o-cresol (4,6-)
Dinoseb
Disulfoton
Epichlorohydrin
Ethyl ether
Ethyl-4,4'-dichlorobenzllate
Ethylenimine
Fluoroace tamlde
Fur an
Ueptachlor
Hexachlorocyclohexane (a-)
-------
TABLE 7 (Continued)
Rank: Persistence (i.e.. 0.1 days < half-life) (Continued)
Hezachlorocyclopentadiene
Hydraz ine
Isosafrole
Lindane
Mercury
Hethapyrilene
Methyl ethyl ketone
Methyl methacrylate
Methyllacetonitrile (2-)
Methylene chloride
Mltomycln C
Naphthylamine (1-)
Nickel
Nitro-o-toluidlne (5-)
Nltrophenol (4-)
Nitroso-n-ethylurea (n-)
Nitrosodiethanolamine (n-)
Nltrosoplperidine (n-)
Octachlorocamphene
Paraldehyde
Pentachloroethane
Pentadlene (1,3-)
Phenyl-thiourea (n-)
Plcollne (2-)
Propane nltrlle
Pyrene
Reserplne
Safrole
Silver
Strychnine
Hexachloroethane
Indeno(1,2,3-cd)pyrene
Kepone
Malononitrile
Methanethlol
Methorny1
Methyl hydrazine
Methyl parathion
Methylcholanthrene (3-)
Methylenebls (2-chloroanlllne) (4,4
Naphthalene
Naphthylamine (2-)
Nickel carbonyl
Nitrobenzene
Nitropropane (2-)
Nitroso-n-methyl urethane (n-)
Nitrosodiethylamlne (n-)
Nitrosopyrrolidlne (n-)
Osmium tetroxide
Parathion
Pentachloronitrobenzene
Phenacetin
Phorate
Pronamide
Propane sultone (1,3-)
Pyrldinamlne (4-)
Resorcinol
Selenium
Silvex
T (2.4,5-)
Hexachlorohexahydro-exo,
exo-d ime thanonaphthalene
Isobutanol
Lead
Melphalan
Methanol
Methyl aziridine
Methyl iodide
Methyl-2-pentanone (4-)
Methylene bromide
-) Methylthiouracil
Naphthalenedione (1,4-)
Naphthylthiourea (a-)
Nicotine
Nitroglycerin
Nitroso-di-n-butylamine (n-)
Nitroso-n-methylurea (n-)
Nltrosomethylvinylamine (n-)
0-Nitrotoluene
PCB-1254
Pentachlorobenzene
Pentachlorophenol
Phenylmercurie acetate
Phosgene
Propanamlne (1-)
Propyn-1-ol (2-)
Pyridine
Saccharin
Selenium dioxide
Streptozotocin
Tetrachlorobenzene (1,2,4,5-)
-------
TABLE 7 (Concluded)
Rank: Persistence (I.e.. 0.1 days < half-life) (Concluded)
Tetrachloroethane (1,1,1,2-) Tetrachloroethane (1,1,2,2-) Tetrachloroethene
Tetrachloroethylene Tetrachloromethane Tetrachlorophenol (2,3,4,6-)
Tetrahydrofuran Tetranltromethane Thlfanox
Toluene Toluenediamine Toluldlne hydrochlorlde (o-)
Toxaphene Trlchloroacetaldehyde Trlchloroethane (1,1,1-)
Trlchloroethane (1,1,2-) Trlchloroethene Trichloroethylene
Trlchloromethyl mercaptan Trichloromonofluoromethane Trichlorophenol (2,4,5-)
Trichlorophenol (2,4,6-) Trls(2,3-dlbromopropyl)phosphate Uracll.5-[bis
(2-chloromethyl)amlno]
Warfarin Xylene Zinc
-------
5.0 DISCUSSION AND CONCLUSIONS
The current HRS considers biodegradability of hazardous
substances as the sole mechanism affecting their persistence in the
environment. Biodegradation, however, is only one of several
physical, biological and chemical processes that play a role in the
persistence of substances in the environment and, in some instances,
may be insignificant relative to other processes. This study has
examined alternatives for incorporating in the HRS the consideration
of five additional processes: hydrolysis, photolysis, volatilization,
free-radical oxidation, and sorption. Of these, sorption has been
identified as the process having the greatest effect in streams and
rivers over the distances currently considered in the HRS. Dilution
is not considered in this study but may, under some circumstances,
overshadow these processes and should be examined independently.
5.1 Comparison of the Two Alternative Persistence Ranking Methods
The two alternative persistence ranking methods described in
Section 4 differ in the number of environmental attenuation processes
considered. Alternative I considers the effect of sorption and the
decay processes of biodegradation, hydrolysis, photolysis,
free-radical oxidation, and volatilization. Alternative II considers
the effect of only the five latter decay processes. A comparison of
the two alternatives are discussed below.
If sorption is not considered, substances may be ranked
according to their estimated decay half-lives. Therefore,
71
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Alternative II would be more easily implemented since it requires
only look-up tables that can be prepared from estimated half-lives.
However, if sorption followed by settling is truly a loss
process, the omission of the sorption process may significantly
alter the accuracy of an estimate of actual environmental attenuation
potentials among substances. This is especially true for streams
and rivers where sorption, followed by settling, may potentially be
the dominant loss mechanism for a majority of substances over the
target distance limits considered. In lakes and reservoirs these
substances may be less persistent than in streams and rivers because
of the longer reaction time in lakes and reservoirs and because
lakes and reservoirs tend to be good sediment traps.
Metals, because of their high partition coefficients, are more
likely to be affected by sorption than organics. If sorption is not
included in ranking the persistence of substances, metals will
always be considered as the most persistent group.
Alternative I could be considered preferable based on the
assumption that the persistence of substances is solely a function
of various loss mechanisms in the surface water column. However,
Alternative I disregards possible ecological effects caused by
contaminated sediments or other effects from the resuspension of the
contaminated sediments. Alternative II would be a better mechanism
to consider these effects.
Another potential disadvantage of Alternative I is that, when
sorption is considered, site measurements are required in order to
72
-------
quantify the settling loss rate between the two locations of
interest. Parameters requiring measurement include: suspended
solids concentrations near the point of entry and at a downstream
location, and organic carbon content of the suspended solids.
Suspended solids concentration has been included in most water
quality monitoring programs. For eample, the U.S. Geological
Survey routinely measures the suspended solids concentration on its
NASQAN stations (Britton et al., 1983). Although it is unlikely
that the NASQAN stations will provide information for the variation
of suspended solids concentration within less than a three-mile
distance, the information from the two nearest NASQAN stations may
provide useful guidelines on the design of the sampling program for
determining suspended solids concentrations for use in persistence
ranking. In addition, programmatic decisions can be made which
further simplify or even dictate the extent of the sampling
program. For example, EPA could decide that the low-flow period is
the critical period (because of its lower dilution capacity), and
that sampling should be conducted during this period.
5.2 Comparison With the Current HRS Persistence Ranking Method
The two alternatives discussed in Section 4, in addition to
being more theoretically sound than the current method in the HRS,
offer the advantages of consistency and traceability in comparison
with the current persistence ranking method. In both alternatives,
the persistence rank of a substance is based on the expected change
73
-------
of the substance concentration over the target distance limit
currently specified in the HRS.
Different effects are expected on the current persistence ranks
of substances if either of the two proposed alternatives are used.
The application of Alternative I could be expected to lower the
ranking of a substance (e.g., from persistence to moderate) if the
sedimentation loss is significant at the site or if biodegradation
is not the dominant decay process. The application of Alternative II
could be expected to lower the ranking of a substance if biodegrad-
ation is not the dominant decay process.
Even without sorption and subsequent sedimentation loss, the
consideration of hydrolysis, photolysis, free-radical oxidation, and
volatilization, in addition to biodegradation, may affect the
current persistence ranking of substances. The ranks of some
substances may be lowered, compared with their current HRS
persistence ranks, because their half-lives are very short as a
result of decay processes other than biodegradation. For example,
bis(chloromethyl)ether, currently ranked as "persistent," would be
ranked as "nonpersistent" in streams and rivers because of its short
half-life (less than 0.01 days) due to rapid hydrolysis.
Other substances, however, may have their rank values increased
(e.g., from low to persistent). Ranks could be increased because
the qualitative basis in the current method may not be consistent
with the quantitative evaluation of half-life in the proposed
74
-------
method. For example, a substance currently ranked low may actually
have a longer biological half-life than a substance currently ranked
moderate. Additionally, the proposed ranking methods consider the
effect of travel time or residence time (i.e., the available time
for reaction) in the environment whereas the current method does
not. As a result, the proposed ranking methods are not likely to
produce the same grouping as the existing HRS method.
In fact, more substances would likely be classified as
persistent with the application of either of the proposed
alternatives than under the present system. Of the more than 250
hazardous substances listed in Appendix B, more than 90 percent are
ranked as persistent in streams and rivers under Alternative II.
This result might initially appear illogical because the more
decay processes considered, the less persistent a chemical might be
expected to be. However, it should be noted that the current
persistence ranking method differs from the proposed alternatives
not only in the number of decay processes considered but also in the
manner in which the "break" points of different ranks are selected.
The current method ranks substances according to a qualitative
relative estimate of biodegradability without assessing the
significance of a particular rate of biodegradation in a given
environment. Because of the relatively short travel time expected
over the target distance limit in streams and rivers (0.1 days),
many chemicals which are usually considered easily biodegradable
75
-------
would be regarded as persistent according to the proposed
methodologies. For example, acetone with a biodegradation half-life
of five days is currently classified as easily biodegradable and is
currently ranked as "nonpersistent." However, it would be classified
as persistent in streams and rivers according to the proposed
alternatives because only a one percent change in concentration is
expected from the point of entry to the target distance limit.
EPA may consider extending the target distance limit in surface
water in view of the findings from Burger and Rushner (1986). For
illustrative purposes, if the target distance limit is extended to
15 miles, then substances would be ranked as follows according to
Alternative II:
Streams and Rivers
(assuming 0.5 day travel time)
Rank
Persistent
Moderate
Low
Nonpersistent
C/C
o_
0.5 < c/c0
o.i < c/c0 < 0.5
o.ooi < C/GO < o.i
< o.ooi
Criterion
0.5 days < half-life
0.1 days < half-life < 0.5 days
0.05 days < half-life < 0.1 days
half-life < 0.05 days
Lakes and Reservoirs
(assuming 30 days travel time)
Rank
Persistent
Moderate
Low
Nonpersistent
c/c
Criterion
0.5 <
0.1 < C/Ci < 0.5
0.001 < C/Ci < 0.1
< 0.001
20 days < half-life
2 days < half-life < 20 days
0.02 days < half-life < 2 days
half-life < 0.02 days
76
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Even under these conditions, only a small number of substances are
expected to be ranked as less than persistent in streams and rivers,
as illustrated in Table 8.
The possibility of limiting the ranking of substances to
biodegradation processes rather than considering the other decay
processes also has been evaluated. Thirty-two substances listed in
Appendix B have half-lives of one day or less. The dominant decay
processes for these 32 substances are tabulated in Table 9.
Hydrolysis is the dominant process for 16 of these substances,
including all of the substances with half-lives less than 0.01 days.
Volatilization dominates this decay of 6 other substances, and
photolysis dominates 3 other substances. Biodegradation is the
dominant process for only 3 of the substances, illustrating the
inadequacy of this factor as the sole criterion for ranking the
persistence of substances in surface water.
77
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TABLE 8
CLASSIFICATION OF HAZARDOUS SUBSTANCES BY THEIR HALF-LIVES--STREAMS/RIVERS II*
Rank: Nonperslstent (i.e.. half-life < 0.05 day)
Acetyl chloride
Benzothrichloride
Dimethylcarbamoyl chloride
Methyl chlorocarbonate
Toluene dilsocyanate
Benzal chloride
Bis (chloromethyl) ether
Diphenylhydrazine (1,2-)
Methyl isocyanate
Benzene sulfonyl chloride
Chloromethyl methyl ether
Maleic anhydride
Phthalic anhydride
Rank: Low (i.e.. 0.05 day < half-life & 0.1 day)
Dichlorobenzidine (3,3'-) Dimethyl sulfate
Phenol
00
Rank: Moderate (i.e. . 0.1 day < half-life < 0.5 day)
Benidine
Heptachlor
Benzyl Chloride
Hexachlorocyclopentadiene
Dipropylamlne
Rank: Persistent (I.e.. 0.5 day < half-life)
(Aminomethyl)-3-lsoxazolol (5-)
Acetone
Acetylaminofluorene (2-)
Acrylic acid
Aldicarb
Aniline
Arsenic (lll)oxide
Benzanthracene (1,2-)
Benzenethiol
Benzo(b)fluoranthene
Benzyl chloride
Acenaphthylene
Acetonitrile
Acrolein
Acrylonitrile
Allyl Alcohol
Anthracene
Asbestos
Benzene
Benzo(a)anthracene
Benzoquinone (p-)
Bioxirane (2,2-)
Acetaldehyde
Acetophenone
Acrylamide
Aldrin
Ammonium Picrate
Arsenic
Benzacridine (3,4-)
Benzene, 1.3,5-trinitro
Benzo(a)pyrene
Benzotrichlorlde
Bis (2-chloroisopropyl) ether
*Assuming a travel distance of 15 miles in 0.5 days.
-------
TABLE 8 (Continued)
Rank: Persistent (I.e.. 0.5 day < half-life) (Continued)
Sis-2-chloromethoxymethane
Bromopropyl phenyl ether (4-)
Butanone (2-)
Chlorambucil
Chloro-2,3-epoxypropane (1-)
Chloroacetaldehyde
Chloroethene
Chlorophenol (o-)
Chromium
Cresols
Cyclohexane
Cyclophosphamide
ODD
Di-n-octylphthalate
Dibenz(a,h)anthracene
Dibutyl phthalate
Dichlorobenzene (1,4-)
Dichloroethane (1,2-)
Dtchloroethylene (trans) (1,2-)
Dichlorophenol (2,6-)
Dieldrin
Diethylene dioxide (1,4-)
Diisopropyl fluorophosphate
Dimethylamine
DimethyInltrosamine
Dimethyl phthalate
Dinitrotoluene (2,6-)
Diphenylhydraz ine (1,2-)
Endrln
Ethyl carbamate
Ethyl methanesulfonate
Ethylene oxide
Fluoranthene
Bromoacetone
Bruc ine
Cadmium
Chlordane
Chloro-m-cresol (4-)
Chloroanlline (p-)
Chloroethyl vinyl ether (2-)
Chlorophenyl thiourea (l-o-)
Chrysene
Crotonaldehyde
Cyc1ohexanone
D (2,4-)
DDT
Di-n-propylnitrosamine
D ibenzopyrene (1,2,7,8-)
Dichloro-2-butene (1,4-)
Dichlorodifluoromethane
Dichloroethene
Dlchloromethane
Dichloropropane (1,2-)
Dlepoxybutene (1,2,3,4-)
Diethylphthalate
Dimethoate
DimethyIbenz[a]anthracene (7,12-)
Dimethylphenethylamine (0,0-)
Dinitro-o-cresol (4,6-)
Dinoseb
Disulfoton
Epichlorohydrin
Ethyl ether
Ethyl-4,4'-dichlorobenzilate
Ethylenimine
Fluoroacetamide
Bromemethane
Butanol (n-)
Carbon tetrachlorlde
Chlornaphaz ine
Chloro-o-toluidine (4-)
Chlorobenzene
Chloromethane
Chloropropionitrile (3-)
Copper
Cumene
Cyclohexyl-4,6-dinitrophenol (2-)
D salts and esters (2,4-)
Daunomyc in
Diallate
Dibromo-3-chloropropane (1,2-)
Dichlorobenzene (1,2-)
Dichloroethane (1,1-)
Dichloroethylene (cis) (1,2-)
Dichlorophenol (2,4-)
Dichloropropane (1,3-)
Diethyl-o-pyrazinyl-
phosphorothioate (0.0)
Diethylstilbestrol
Dimethoxybenzidine (3,3-)
Dimethylbenzidine (3,3-)
Dimethylphenol (2,4-)
Dinitrotoluene (2,4-)
Dioxane (1.4-)
Endosulfan
Ethyl acrylate
Ethyl methacrylate
Ethylene dibromide
Ethylenebis(dithiocarbamic acid)
Formaldehyde
-------
TABLE 8 (Continued)
Rank: Persistence (i.e., 0.5 days < half-life) (Continued)
GO
O
Formic acid
Glycidylaldehyde
Hexachlorocyclohexane (a-)
Hydrazine
Isosafrole
Lindane
Mercury
Methapyrilene
Methyl chlorocarbonate
Methyl iodide
Methyl-2-pentanone (4-)
Methylene bromide
Methylthiouracil
Naphthalenedione (1,4-)
Naphthylthiourea (a-)
Nicotine
Nitroglycerin
Nltroso-dl-n-butylamine (n-)
Nitroso-n-methylurea (n-)
Nitrosomethylvinylamine (n-)
0-Nitrotoluene
PCB-1254
Pentachlorobenzene
Pentachlorophenol
Phenylmercuric acetate
Phosgene
Propanamine (1-)
Propyn-1-ol (2-)
Pyridlne
Saccharin
Selenium dioxide
Streptozotocln
Fur an
Hexachlorobenzene
Hexachloroethane
Indeno(l,2,3-cd)pyrene
Kepone
Malononitrile
Methanethiol
Methorny1
Methyl ethyl ketone
Methyl methacrylate
Methyllacetonitrile (2-)
Methylene chloride
Mitomycin C
Naphthylamine (1-)
Nickel
Nitro-o-toluidine (5-)
Nitrophenol (4-)
Nitroso-n-ethylurea (n-)
Nitrosodiethanolamlne (n-)
Nitrosopiperidine (n-)
Octachlorocamphene
Paraldehyde
Pentachloroe thane
Pentadlene (1,3-)
Phenyl-thiourea (n-)
Picoline (2-)
Propanenitrile
Pyrene
Reserpine
Safrole
Silver
Strychnine
Furfural
Hexachlorobutadiene
Hexachlorohexahydro-exo,
exo-dimethanonaphthalene
Isobutanol
Lead
Melphalan
Methanol
Methyl aziridine
Methyl hydrazlne
Methyl parathion
Methylcholanthrene (3-)
Methylenebis
(2-chloroanlllne) (4.4'-)
Naphthalene
Naphthylamine (2-)
Nickel carbonyl
Nitrobenzene
Nitropropane (2-)
Nltroso-n-methyl urethane (n-)
Nltrosodiethylamine (n-)
Nitrosopyrrolidine (n-)
Osmium tetroxide
Parathion
Pentachloronltrobenzene
Phenacetln
Phorate
Pronamlde
Propane sultone (1,3-)
Pyridinamine (4-)
Resorcinol
Selenium
Silvex
T (2,4.5-)
-------
TABLE 8 (Concluded)
Rank: Persistence (i.e.. 0.5 days < half-life) (Concluded)
oo
Tecrachlorobenzene (1,2,4,5-)
Tetrachloroethene
Tetrachlorophenol (2,3,4,6-)
Thlfanox
Toluldlne hydrochlorlde (o-)
Trlchloroethane (1,1,1-)
Tr ichloroethy1ene
Trichlorophenol (2,4,5-)
Uracll,5[bls(2-chloromethyl)amlno
Zinc
Tetrachloroethane (1,1,1,2-)
Tetrachloroethylene
Tetrahydrofuran
Toluene
Toxaphene
Trlchloroethane (1,1,2-)
Trlchloromethyl mercaptan
Trichlorophenol (2,4,6-)
Warfarin
Tetrachloroethane (1,1,2,2-)
Tetrachlorome thane
Tetranltromethane
Toluenedlamlne
Trlchloroacetaldehyde
Trichloroethene
Trlchloromonofluoromethane
Trls(2,3-dlbroitopropyl)phosphate
Xylene
-------
OO
TABLE 9
THE DOMINANT PROCESS FOR SUBSTANCES WITH HALF-LIFE EQUAL TO OR LESS THAN 1 DAY
Dominant Process
Hydrolysis and
Half-Life, Free-Radical Volatilization and Free-Radical
t. ,., (days) Biodegradation Hydrolysis Photolysis Volatilization Oxidation Biodegradatlon Oxidation
< 0.01 12
0.01 < ti/2 < 0.1 1 1 1 1
0.1 < t!/2 < 1 2 3 2 6 1 1 1
Note: Numbers shown in the table represent the total number of substances belonging to the identified category.
0.01 day = 15 minutes
0.1 day = 2.4 hours
-------
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89
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APPENDIX A
REVIEW OF PERSISTENCE FACTORS IN OTHER SITE RANKING SYSTEMS
This appendix reviews the persistence factors that have been
incorporated in 11 other systems used to rank the threat posed by
hazardous waste sites. The review focuses on how the persistence
factors are used in the various systems and how persistence is
defined and evaluated in the various ranking systems. If more than
one transport pathway is considered, the review focuses on the
surface water pathway. Important similarities and differences
between these factors and the HRS persistence factor are identified.
The 11 ranking systems reviewed are:
• JRB Methodology
• HARM
• HARM II
• CSR
• ADL
• S.P.A.C.E. for Health
• Dames and Moore Methodology
• PERCO
• SAS
• Action Alert System
• RAPS
91
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A.I JRB Methodology
The JRB methodology was developed by JRB Associates, Inc. to
evaluate the relative potential environmental impact among land based
hazardous waste disposal sites (JRB, 1980). It considers four
generic areas: receptors, pathways, waste characteristics, and waste
management practices.
Waste characteristics are evaluated based on nine factors,
including a persistence factor. In considering persistence, each
waste is assigned an integer value of 0, 1, 2, or 3 depending on the
biodegradability of the waste:
Characteristics Rating Scale Levels
Easily biodegradable compounds 0
Straight chain hydrocarbon 1
Substituted and other ring 2
compounds
Metals, polycyclic compounds 3
and halogenated hydrocarbons
A look-up table was prepared for more than one hundred chemicals.
Both the persistence rating criteria and the look-up tables from
the JRB methodology are adopted in the current HRS.
A.2 HARM
The Hazard Assessment Rating Methodology (HARM) is used by the
U.S. Air Force to rank hazardous substance sites for priority
attention for follow-on site investigations and confirmation
activities under Phase II of the Air Force's Installation
92
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Restoration Program (IRP). HARM is designed to use data developed
during the Record Search (Phase I) portion of the IRP (Engineering-
Science, 1983). Record Searches are essentially equivalent to EPA
Preliminary Assessments.
The HARM score is developed from four subscores: receptors,
pathways, waste characteristics, and waste management practices. A
total risk is estimated by averaging and normalizing the first three
subscores.
Waste persistence is one of the three factors considered in
waste characteristics. Depending on the persistence of the waste,
each waste is assigned a value called "persistence multiplier."
Persistence Criteria Persistence Multiplier
Metals, polycyclic compounds, 1.0
and halogenated hydrocarbons
Substituted and other ring 0.9
compounds
Straight chain hydrocarbons 0.8
Easily biodegradable compounds 0.4
Despite the difference in values assigned to each rank, the criteria
used in HARM are the same as those used in the current HRS.
A. 3 HARM II
The Hazard Assessment Rating Methodology II (HARM II) is a
modification and extension of the HARM system that is intended to
permit the use of site-specific monitoring data in setting
priorities. HARM II is used by the U.S. Air Force in Phase II of
93
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the IRP program to set priorities for detailed site investigations and
possible remedial action (Barnthouse et al., 1986).
When the measured contaminant concentration is used to assess the
health and ecological hazards of contaminants, there is no need to
evaluate persistence. In the absence of measured concentration data,
the persistence multiplier (M ) is used with several other factors
to calculate the health hazard score and the ecological hazard score.
The persistence multiplier used in HARM II is the same as that
defined in HARM, and therefore is based on the same criteria as is
employed in the current HRS.
A.4 CSR
The Confirmation Study Rating (CSR) model is used by the
U.S. Navy in the Navy Assessment and Control of Installation
Pollutants (NACIP) Program to assign priorities for further study to
hazardous substance sites. The CSR model is based on the HARM system
and the JRB model, but differs from them in several areas including
the waste characteristics scoring approach (Luecker, 1982).
Nonetheless, persistence, which is one of the 13 factors considered in
the waste characteristics section, is evaluated according to the
identical criteria as those in the JRB model. Since persistence in
the current HRS is adopted from the JRB model, persistence in the CSR
model is evaluated in the same manner as in the current HRS.
94
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A.5 ADL
The Arthur D. Little, Inc. (ADL) system is an adaptation of the
HRS that was developed for the Chemical Manufacturers Association
(Fiksel and Segal, 1982).
Persistence is one of the seven factors considered in evaluating
the amount of waste released from a site. Persistence of waste is
evaluated in the same manner as in the current HRS.
A.6 S.P.A.C.E. for Health
The System for Prevention, Assessment, and Control of Exposures
and Health Effects from hazardous sites (S.P.A.C.E. for Health) was
developed by the Centers for Disease Control (CDC) for use in public
health assessments of hazardous sites (French et al., 1984; Kay and
Tate, 1984). The system is used to assign priorities to sites, based
on the potential of the site to endanger human health.
Site characteristics is one of four factors used in S.P.A.C.E.
for Health for determining the site priority. Site characteristics
include seven factors, and the persistence of the five most hazardous
substances at a site is one of the factors considered. Persistence of
a substance is determined by using the same look-up tables that are in
the current HRS.
A.7 Dames and Moore Methodology
The Dames and Moore Methodology was developed to evaluate waste
disposal sites with respect to their potential for ground and surface
water contamination (Dames and Moore, undated).
95
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It consists of four rating areas. One of these rating areas is
Material Hazards Rating, which includes persistence as one of seven
rating factors. Persistence of a hazardous substance is assigned a
rating value of 0, 1, 2, or 3, depending on the biodegradability of
the hazardous substance. The criteria for evaluating the
biodegradability of a hazardous substance are the same as those in the
current HRS. No look-up table is presented.
A.8 PERCO
The Prioritization of Environmental Risks and Control Options
(PERCO) model (Arthur D. Little, Inc., 1983) was developed for the
Massachusetts Department of Environmental Quality Engineering for use
in ranking contaminated sites in terms of immediate and long-term
environmental and human health hazards. The ranking is used to
provide a rationale for allocation of state remedial action funds.
PERCO evaluates the potential risks posed by a site by
considering the following six migration paths: air, ground water,
surface water, soil/direct contact, fire/explosion, and flood.
In the surface water pathway, an attenuation score is used to
identify sites with similar characteristics. Persistence of waste is
one of the factors considered in the attenuation score. There is no
clear description on how persistence is ranked in the surface water
pathway; however, in scoring persistence of hazardous substances
through flood, PERCO suggests using the following criteria:
96
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Criteria Persistence score
Easily biodegradable compounds 2
and straight chain hydrocarbons
Substituted and other ring compounds; 3
metals, polycyclic compounds and
halogenated hydrocarbons
This scoring scheme differs from the current HRS in that
persistence scores become higher for most substances: substances
that receive a score of 0 or 1 in the current HRS will receive a
score of 2 in PERCO; substances that receive a score of 2 or 3 in
the current HRS will receive a score of 3 in PERCO.
PERCO made the changes based on the consideration that areas
less than several miles downstream of a waste site may not
necessarily benefit from any lack of long-term persistence.
A. 9 SAS
The Site Assessment System (Michigan, 1983) is used to assess
and prioritize release sites for further investigation and possible
remedial action.
Persistence is one of the seven factors considered in
evaluating the chemical hazard of a substance. Persistence is
defined as follows:
Criteria Persistence Score
Half-life in soil, air or 5
water < 6 months
Half-life in soil, air or 0
water < 6 months
97
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No tables are available on the expected half-lives for various
substances considered.
A.10 The Action Alert System
The Action Alert System (AAS) was developed to support the
Monitoring and Data Support Division, Office of Water Regulations and
Standards (OWRS), U.S. EPA. The purpose of the AAS is to serve as a
screening tool that separates large numbers of priority pollutants
into more manageable clusters (Fiksel and Segal, 1980).
The underlying conceptual framework for the Action Alert System
consists of a hierarchy of data elements. Environmental concentration
of the toxic pollutant is required to evaluate the effect and the
hazard.
Environmental concentration is estimated using information on the
release rate of the substances and their environmental fates. The
term "persistence" is not explicitly used. Instead, rates are
estimated for several environmental loss processes in predicting the
environmental fate of substances. The loss processes considered are
hydrolysis, photolysis, free-radical oxidation, and volatilization.
A. 11 RAPS
The Remedial Action Priority System (RAPS) was developed for the
U.S. Department of Energy to more realistically assess the risks posed
by radioactive waste constituents. RAPS considers four major pathways
for contaminant migration: ground water, overland, surface water, and
atmosphere (Whelan et al., 1986).
98
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In estimating the contaminant concentration in the surface water
pathway, RAPS uses the steady-state, vertically integrated mass
balance equation:
in which
f£ = 0 at y = 0 and y = B
dy
where C = Dissolved in-stream contaminant concentration.
u = Average stream flow velocity.
Ey = Lateral or transverse dispersion coefficient.
B = Width of stream.
Y = Degradation/decay constant (0.693/half-life).
There is no further elaboration on the number of processes
which are considered in estimating the degradation/decay constant.
In the case of the examples illustrated in the reference document,
arsenic is given a half-life of 8 years and Strontium-90 is given a
half -life of 28.5 years.
99
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APPENDIX B
ILLUSTRATIVE HALF-LIVES OF SUBSTANCES IN STREAMS/RIVERS
The half-life values presented in this appendix are based on a
limited sample of comprehensive literature review articles. As a
result, the half-life values in the appendix may not be the best
available estimates. Moreover, the values in these review articles
may not have been estimated in a manner consistent with the
methodology described in Appendix G. As a result, these half-life
values should be used for illustrative purposes only. Specifically,
these values were collected for preliminary assessment on the
availability of the data, and to estimate the feasibility and
sensitivity of the proposed ranking methods.
101
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TABLE B-l
ILLUSTRATIVE HALF-LIVES OF SUBSTANCES IN STREAMS/RIVERS
Dominant
Waste Name
Acenaphthylene
Acetaldehyde
Acetone
Acetonitrile
Acetophenone
Acetyl Chloride
Acetylaminofluorene (2-)
Acrolein
AeryI amide
Acrylic acid
Acrylonitrile
Aldicarb
Aldrin
Allyl alcohol
Ammoniun Picrate
An iIi ne
Anthracene
Arsenic
Arsenic III oxide
Asbestos
a-naphthylthiourea
Benzacridine (3,4-)
Benzal chloride
Benzanthracene (1,2-)
Benzene
Benzenethiol
Benzene, 1,3,5-trinitro
Benzensulfonyl Chloride
Benzidine
Benzoquinone (p-)
Benzotrichloride
Benzo(a)anthracene
Benzo(b)fluoranthene
Benzo(a)pyrene
Benzyl Chloride
Bioxirane (2,2-)
Bis(chloromethyl)ether
Bis-2-chloroisopropyl ether
8is-2-chloromethoxymethane
Bromoacetone
Bromoform
Bromomethane
Process
H P V
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
Half-life
0 (days)
3.8
1.0
5.0
7.0
<13
0.00000006
>365
2.6
>»365
2.1
>365
2.8
8
<32
<47
1.3
999
999
999
>365
999
0.005
999
1.3
1.8
1.9
0.0026
* 0.262
>5
0.002
3.8
3.8
1.2
0.37
29
0.00029
3.4
>365
175
2.3
1.2
References &
Comments
4a
4
1,2,3
4
1,2.3
1,2.3
1,2,3
1,2,3
1,2,3
1.2,3
4
1,2.3
1,2,3
1,2,3
1,2,3; explosive
1,2,3
5
1,2,3
1,2,3
7
1,2,3
1,2.3
1,2,3
1,2,3
4
1,2,3
1,2,3
1,2,3
6
1,2,3
1.2,3
4a
4a
4a
1,2,3
1,2,3
1
1,2,3
1,2,3
1,2,3; poisonous gas
1,2,3
1,2,3
102
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TABLE B-l (Continued)
Waste Name
Bromopropyl phenyl ether (4-)
Brucine
Butanol (n-)
Butanone (2-)
Cadmium
Carbon tetrachloride
Chlorambucil
Chlordane
Chlornaphazine
Chloroacetaldehyde
Chloroaniline Cp-)
Chlorobenzene
Chloroethene
Chloroethyl vinyl ether (2-)
Chloroform
Chloromethane
Chloromethyl methyl ether
Chloronapthalene (B-)
Chlorophenol (o-)
Chloropropionitrile (3-)
Chloro-2,3-epoxypropane (1-)
Chloro-m-cresol (4-)
Chloro-o-toluidine (4-)
Chromiifn
Chrysene
Copper
Cresols
Crotonaldehyde
Cumene
Cyclohexane
Cyclohexanone
Cyclohexyl-4,6-dinitrophenol (2-
Cyflophosphamide
Oaunomycin
ODD
DDT
D(2,4)
D(2,4) salts and esters
Diallate
Dibenzopyrene (1,2,7,8-)
Dibenz(a,h)anthracene
Dibromo-3-Chloropropane (1,2-)
Dominant
Process
B H P V 0
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
+
Half-life
(days)
2.0
>365
19.0
6.3
999
1.3
<365
4.2
<365
1.25
57
1.4
1.0
1.5
1.2
0.9
0.00029
2.1
>5; <37
4.1
4.9
18
999
6
999
8
12
1.4
1.1
2.2
<365
>365
2.2
7.4
999
>365
3.2
999
3.8
3.2
References &
Comments
1,2,3
1,2,3
1,2,3
1,2,3
1,2,3
1,2,3
4
1,2,3
4
1,2,3
4
1,2,3
1,2,3
4
1,2,3
1,2,3
1,2,3
1,2,3
1,2,3
1,2.3
1,2,3
1,2,3
4a
1,2,3
1,2,3
1,2,3
1,2,3
1,2,3
1,2,3
1,2,3
1,2,3
,2,3
,2,3
,2,3
,2,3
,2,3
,2,3
4a
1,2,3
103
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TABLE B-l (Continued)
Dominant +
Process Half-life References &
Waste Name B H P V 0 (days) Comments
Dibutylphthalate * >80 1-2'3
Dichlorobenzene (1,2-) * 1.5 *
Dichlorobenzene (1,4-) * 1.5 *
Dichlorobenzidine (3,3'-) * °-06 5
Dichlorodifluoromethane * '•* 1,2,3
Dichloroethane (1,1) * 1-3 1,2,3
Dichtoroethane (1,2-) * !•* 1,2,3
Dichloroethene (1,1-) * 1.0 4
Dichloroethyl ether * 8.2 1,2,3
Dichloroethylene (1,1-) * 1.2 1,2,3
Dichloroethylene (CIS) (1,2-) * 1.2 1,2,3
Dichloroethylene (trans) (1,2-) * 1.2 1,2,3
Dichloromethane * 1.2 4
Dichlorophenot (2,4-) * 6.0 4
Dichlorophenol (2,6-) * 6.0 4
Dichloropropane (1,2-) * 1.4 4
Dichloro-2-butene (1,4-) * 3.8 1,2,3
Dieldrin * 28 1,2,3
Diethylphthalate * 6.4 1,2,3
Diethylstilbesterol 999 1,2,3
Diethyl-o-pyrazinyl- (0,0) 1,2,3
phosphorothioate * 28.3 1,2,3
Diisopropylfluorophosphate * 23.3 1,2,3
Dimethoate 289 1,2,3
Dimethoxybenzidine (3,3'-) 999 1,2,3
Dimethyl sulfate * 0.05 1,2,3
Dimethylamine 999 1,2,3
Dimethylbenzidine (3,3'-) 999 1,2,3
Dimethylbenz[A]anthracene (7,12-) 999 1,2,3
Dimethylcarbamoyl chloride * 0.0029 1,2,3
Dimethylnitrosamine 999 1,2,3
Dimethylphenethylamine (a,a-) * 11.1 1,2,3
Dimethylphenol (2,4-) * 3.0 4
Dimethylphthalate * >12 1,2,3
Dinitrotoluene (2,4-) * 12 4a
Dinitrotoluene (2,6-) * 0.35 5
Dinitro-o-cresol (4,6-) 75; <150 1,2,3
Dinoseb * 3.1 1,2,3
Dioxane (1,4-) * 200 1,2,3
Diphenylhydrazine (1,2-) * 0.03 6
Dipropylamine * 0.33 1,2,3
Disulfoton >5; <67 1,2.3
104
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TABLE B-l (Continued)
Dominant +
Process Half-life References &
Waste Name B H P V 0 (days) Comments
Di-n-octylphthalate 1,2,3
Di-n-propylnitrosamine * 25 1,2,3
Endosulfan * >5; <14 1,2,3
Endrin >5; <68 1,2,3
Epichlorohydrin * 3.5 4
Ethtlene oxide * 3.6 1,2,3
Ethyl acrylate * 2.6 1,2,3
Ethyl carbamate >365 1,2,3
Ethyl ether * 1.2 1,2,3
Ethyl methacrylate * 2.4 1,2,3
Ethylene dibromide * 2.0 1,2,3
Ethylenimine * 5.0 1,2,3
Ethylmethanesulfonate * 0.8 1
Ethyl-4,4'-dichlorobenzilate >7.2 1,2,3
Etylenebis(dithiocarbamic acid) >365 1,2,3
Fluoranthene * 15 4a
Fluoroacetamide >365 1,2,3
Formaldehyde * .9 4
Formic acid 1,2,3
Furan * 1.1 1,2,3
Furfural * 0.6 1,2,3
Glycidylaldehyde * 29 1,2,3
Heptachlor * * 0.5 4,6
Hexachlorobenzene * 2.0 4
Hexachlorobutadiene * 1.5 4
Hexachlorocyclohexane (a-) >365 1,2,3
Hexachlorocyclopentadiene * 0.2 4a
Hexachloroethane * 1.1 4
Hexachlorohexahydro-exo.exo- 1,2,3
dimethanonaphthalene * 2.4 1,2,3
Hydrazine * 75; <145 1,2,3
Indeno(1,2,3-cd)pyrene * 3.8 4a
Isobutanol * 3.4 1,2,3
Isosafrole * * >1; <47 1,2,3
Kepone 1,2,3
Lead 999
Maleic anhydride * 0.0003 1
Malononitrile >365 1,2,3
Helphalan <365 1,2,3
Mercury * 1.7 3
Methanol * 2.4 1,2,3
Hethomyl >365 1,2,3
105
-------
TABLE B-l (Continued)
Waste Name
Methyl aziridine
Methyl Chlorocarbonate
Methyl ethyl ketone
Methyl hydrazine
Methyl iodide
Methyl methacrylate
Methyl isocyanate
Methyl parathion
Methylcholanthrene (3-)
Methylene bromide
Methylene chloride
Methylenebis(Z-chloroaniline) (4,4'-)
Methyllacetonitrile (2-)
MethylthiouraciI
Methyl-2-pentanone (4-)
Mitomycin C
Naphthalene
Naphthalenedione (1,4-)
Naphthylamine (1-)
Naphthylamine (2-)
Nickel
Nickel carbonyl
N i cot i ne
Nitrobenzene
Nitroglycerin
Nitrophenol (4-)
Nitropropane (2-)
Nitro-o-toluidine (5-)
n-Nitrosodiethanolamine
N-Nitrosodiethylamine
N-Nitrosomethylvinylamine
N-Nitrosopiperidine
N-Nitrosopyrrolidine
N-Nitroso-di-n-butylamine
N-Nitroso-N-ethylurea
N-nitroso-N-methyl urethane
N-Nitroso-N-methylurea
N-Phenylthiourea
Octachlorocamphene
0-Nitrotoluene
Osmium tetroxide
Paraldehyde
Dominant
Process
B H P V
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
•f
Half-life
0 (days)
6.1
0.000024
2.0
<25
1.5
1.7
0.0058
90
2.0
2.2
1.2
>365
>365
>365
2.4
999
1.4
44
5.0
999
1.6
>365
12.5
* 14
1.2
2.6
999
250
3.3
2.9
14
1.8
31
1.8
69
>365
2.5
1.4
6.6
6.0
References &
Comments
1.2,3
1,2,3
4
1.2,3
1,2,3
1,2,3
1
1,2,3
1,2,3
1.2,3
1,2.3
1.2,3
1,2,3
1,2,3
1,2.3
1.2,3
1,2,3
1,2,3
1,2,3
1.2,3
1,2,3
1,2,3
4
2; explosive
6
1,2.3
1.2,3
1,2,3
1.2,3
1,2,3
1,2.3
1.2,3
1,2,3
1,2.3
1,2,3
1.2,3
1,2,3
1,2,3
5
1,2.3
1,2.3
106
-------
TABLE B-l (Continued)
Waste Name
Parathion
PCB-1254
PentachIorobenzene
Pentachloroethane
Pentachloroni trobenzene
Pentachlorophenol
Pentadiene (1.3-)
Phenacetin
Phenol
Phenylmercuricacetate
Phorate
Phosgene
Phosphine
Phthalic anhydride
Picoline (2-)
Pronamide
Propanamine (1-)
Propane nitrile
Propane sultone (1,3-)
Propyn-1-o1 (2-)
Pyrene
Pyridinamine (4-)
Pyridine
p-Nitroaniline
Reserpine
Resorcinol
Saccharin
Safrole
Selenium
Selenium dioxide
Silver
Si Ivex
Strychnine
T(2,4,5)
Tetrachlorobenzene (1,2,4,5-)
Tetrachloroethane (1,1,1,2-)
Tetrachloroethane (1,1,2,2)
Tet rachIoroethene
TetrachIoroethyIene
Tetrachloromethane
Tetrachlorophenol (2,3,4,6-)
Tetrahydrofuran
Dominant +
Process Half -life
B H P V 0 (days)
* * 35
* 2.0
* 2.1
* 1.8
* 2.1
* 150
* 1.0
* 140
* 0.1
2.9
* 4.0
* 0.96
* 0.002
* 7.1
* 27
* 6.7
* 5.6
<365
NHYF
* 1.3
* 34
* 2.0
* 3
* 5
>365
* * >1;<19
999
260
999
999
999
999
* 3.9
* 1.6
* 1.8
* 1.4
* 1.6
* 1.5
* 1.8
* 2.2
References &
Comments
4
4
1,2,3
1,2,3
1,2,3
4a
1,2,3
1,2,3
4b
6
4
1,2,3
2; poisonous gas
1.2,3
1,2,3
1,2,3
1,2,3
1,2,3
1,2,3
1,2,3
5
1,2,3
4
1.2,3
1,2,3
1.2,3
1,2,3
1,2,3
7
3
1,2,3
1,2,3
1.2,3
1,2,3
1,2.3
4
4
1,2.3
1.2,3
1.2,3
1.2.3
107
-------
TABLE B-l (Continued)
Dominant +
Process Half-life References &
Waste Name B H P V 0 (days) Comments
Tetranitromethane * 34 1.2.3
Thiofanox <365 1.2,3
Toluene * 1.0 4
Toluene diamine * 30.0 4a
Toluene diisocyanate * 0.0016 1
Toluidine hydrochloride (a-) * 25 1,2,3
Toxaphene * 2.0 4
Trichloroacetaldehyde * 1.7 1,2,3
Trichloroethane (1,1,1-) * 1-3 4
Trichloroethane (1,1,2-) * 1.8 1,2,3
Trichloroethene * 1.3 4
Trichloroethylene * 1.4 1,2,3
Trichloromethyl mercaptan * 3.2 1,2,3
Trichloromonofluoromethane * 1.4 1,2,3
Trichlorophenol (2,4,5-) * 36 1,2,3
Trichtorophenol (2,4,6-) * 13 4
Tris(2,3-dibromopropyl)phosphate * 5.6 1,2,3
Triflurallin * 0.63 5
Urcil,5[Bis-2-chloromethylamino] >365 1,2,3
Warfarin 180 1,2,3
Xylene * 1.5 4
Zinc 999
+ A half-life of 999 days is assigned for elements and substances
with every long half-lives.
1. Wolfe (1985)
2. Environmental Monitoring and Services, Inc. (1985)
3. Estimate using a method similar to that described in ICF
(1984), except that the diffusion coefficients were
estimated using the formula sugested by HydroQual (1982).
The Henry's constants were from U.S. EPA (1985).
4. Environ (1984)
4a. Modified from Environ (1984), the photolysis half-life in Environ
(1984) is for mid-day, near surface situation and is multiplied
by a factor of 30 to represent a daily-average, depth-average
situation with the assumptions of a 2m depth of water and a
diffusion attenuation coefficient of 10 m-1.
108
-------
TABLE B-l (Concluded)
Dominant +
Process Half-life References &
Waste Name B H P V 0 (days) Comments
4b. Photolysis uas one of the dominant processes according to Environ
(1984), however, after the adjustment for a typical surface
water environment as described in 4a, biodegradation becomes
the only dominant process.
5. Modified from Zepp et al., (1984), the literature value is
multiplied by a factor of 30 to represent a daily-average,
depth-average situation with the assumption of a 2m depth of
water and a diffusion attenuation coefficient of 10m-1.
6. Estimated by using the oxidation constants given in Mabey et al.
(1982), and assuming peroxy radical conc.= 10E-9H,
single oxygen conc.=10E-12M.
7. Callahan et al., (1979)
109
-------
APPENDIX C
ILLUSTRATIVE HALF-LIVES OF SUBSTANCES IN LAKES/RESERVOIRS
The half-life values presented in this appendix are based on a
limited sample of comprehensive literature review articles. As a
result, the half-life values in the appendix may not be the best
available estimates. Moreover, the values in these review articles
may not have been estimated in a manner consistent with the
methodology described in Appendix G. As a result, these half-life
values should be used for illustrative purposes only. Specifically,
these values were collected for preliminary assessment on the
availability of the data, and to estimate the feasibility and
sensitivity of the proposed ranking methods.
Ill
-------
TABLE C-l
ILLUSTRATIVE HALF-LIVES OF SUBSTANCES IN LAKES/RESERVOIRS
Waste Name
Acenaphthytene
Acetaldehyde
Acetone
Acetonitrile
Acetophenone
Acetyl Chloride
Acetylaminofluorene (2-)
Acrolein
AeryI amide
Acrylonitrile
Aldicarb
ALdrin
AUyl alcohol
Ammoniun Picrate
Aniline
Anthracene
Arsenic
Arsenic III oxide
Asbestos
a-Chlorophenylthiourea (1-)
a-naphthylthiourea
Benzacridine (3,4-)
Benzal chloride
Benzanthracene (1,2-)
Benzenethiol
Benzene
Benzene, 1,3,5-trinitro
Benzensulfonyl Chloride
Benzidine
Benzo(a)anthracene
Benzo(b)fluoranthene
Benzo(a)pyrene
Benzoquinone (p-)
Benzotrichloride
Benzo[a]pyrene
Benzyl Chloride
Benzylchloride
Bioxirane (2,2-)
Bis-2-chloroisopropyl ether
Bis(chloromethyl)ether
Bis-2-chloromethoxymethane
Bromoacetone
Dominant +
Process Half -life
B H P V 0 Days
* 3.8
* * 1.0
* 5
* 7.0
19
* 0.0000006
>365
* 6
999
* * 5.1
>365
* 17
* 8
* 43
* 53
* 1.3
999
999
999
>365
>365
999
* 0.005
999
* 7.8
* 7.0
* 11.5
* 0.0026
* 0.262
* 3.8
* 3.8
* 1.2
>5
* 0.002
999
* 0.37
* 8.7
* 29
* 11.7
* 0.000129
>365
• 182
References
& Comments
4a
4
1,2,3
4
1,2,3
1,2,3
1,2,3
1,2,3
1,2,3
4
1,2,3
1,2,3
1,2,3
1,2,3
1,2,3
5
1,2,3
1,2,3
7
1,2,3
1,2,3
1,2,3
1,2,3
1,2,3
1,2,3
4
1,2,3
1,2,3
6
4a
4a
4a
1,2,3
1,2,3
1,2,3
1,2,3
1,2,3
1,2,3
1,2,3
1
1,2,3
1,2,3
112
-------
TABLE 0-1 (Continued)
Waste Name
Bromoform
Bromomethane
Bromopropyl phenyl ether (4-)
Brucine
Butanol (n-)
Butanone (2-)
Cadmium
Carbon tetrachloride
Chlorambucil
Chlordane
Chlornaphazine
Chloroacetaldehyde
Chloroaniline (p-)
Chlorobenzene
Chlorodane
Chloroethene
Chloroethyl vinyl ether (2-)
Chloroform
Chloromethane
Chloromethyl methyl ether
Chloconapthalene (B-)
Chlorophenol (o-)
Chloropropionitrile (3-)
Chloro-2,3-epoxypropane (1-)
Chloro-m-cresol (4-)
Chloro-o-toluidine (4-)
Chromium
Chrysene
Copper
Cresols
Crotonaldehyde
Cumene
Cyclohexane
Cyclohexanone
Cyclohexyl-4,6-dinitrophenol (2-)
CycIophosphamide
Daunomycin
ODD
DDT
D(2,4)
D(2,4) salts and esters
Dial late
Dominant
Process
8 H P V 0
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
* *
*
*
*
*
*
*
+
Half-life
Days
13
6.7
12.8
>365
24
11
999
7.3
>365
16
>365
6.1
63
7.8
15.7
5
7.4
6.6
4.3
0.00029
10.0
>5; <44
46.6
10
>365
26
999
6
999
8
>5; <16
4
6
13
13
>365
>365
15
21
999
>365
>5; <15
References
& Comments
,2,3
.2.3
,2.3
.2,3
,2,3
,2.3
1,2,3
4
1,2,3
1,2.3
1.2.3
1.2,3
1,2,3
4
4
1,2.3
1.2,3
4
1.2.3
1,2,3
1,2.3
1,2,3
1,2,3
1.2,3
1,2,3
1.2.3
1.2.3
4a
1,2.3
1,2.3
1,2,3
1,2.3
1,2,3
1,2,3
1,2.3
1,2,3
1,2,3
1.2,3
1,2,3
1.2,3
1,2,3
1.2.3
113
-------
TABLE C-l (Continued)
Waste Name
Dibenzopyrene (1,2,7,8-)
D i benz[a,h]anthracene
Dibromo-3-Chloropropane (1,2-)
Dibutylphthalate
Dichlorobenzene (1,2)
Dichlorobenzene (1,4)
Dichlorobenzidine (3,3'-)
Dichlorodifluoromethane
Dichloroethane (1,1)
Dichloroethane (1,2)
Dichloroethene (1,1)
Dichloroethyl ether
Oichloroethylene (1,1-)
Dichloroethylene (CIS) (1,2-)
Dichloroethylene (trans) (1,2-)
Dichloromethane
Dichlorophenol (2,4)
Dichlorophenol (2,6)
Dichloropropane (1,2-)
Dichloropropane (1,3-)
Dichloro-2-butene (1,4-)
Dieldrin
Diethylenedioxide (1,4-)
Diethylphthalate
Diethylstilbesterol
Diethyl-o-pyrazinyl- (0,0)
phosphorothioate
Di isopropylfluorophosphate
Dimethoate
Dimethoxybenzidine (3,3'-)
Dimethyl sulfate
Dimethylamine
Dimethylbenzidine (3,3'-)
Dimethylbenz[A]anthracene (7,12-)
Dimethylcarbamoy chloride
Dimethylfuran
Dimethylnitrosamine
Dimethylphenethylamine (a,a-)
Dimethylphenot (2,4)
Dimethylphthalate
Dinitrotoluene (2,4-)
Dinitrotoluene (2,6-)
Dominant
Process
B H P V 0
Half-life
Days
999
3.8
14
>80; <230
8.5
8.5
0.06
7.8
6.9
7.0
2.7
16
6.8
6.8
6.8
5.8
6.0
6.0
7.5
7.6
10
>5; <42
>5; <200
16
999
25
32
290
999
0.05
999
999
999
0.0029
0.15
999
19
3.0
>12
12
0.35
References
& Comments
1,2.3
4a
1.2,3
1,2,3
4
4
5
1,2,3
1,2,3
1,2,3
4
1,2,3
1.2.3
1,2,3
1.2,3
4
4
4
.2,3
.2,3
.2,3
.2,3
.2,3
.2,3
.2,3
,2.3
,2,3
,2,3
,2.3
,2.3
,2.3
,2,3
,2,3
,2.3
5
1,2.3
1.2,3
4
1,2,3
4a
5
114
-------
TABLE C-l (Continued)
Waste Name
Dinitro-o-cresol (4,6-)
D i noseb
Dioxane (1,4-)
Diphenylhydrazine (1,2-)
Dipropylanrine
Disulfoton
Di-n-octylphthalate
Di-n-propylnitrosamine
Endosulfan
Endrin
Epichlorohydrin
Ethtlene oxide
Ethyl acrylate
Ethyl acrylate
Ethyl carbamate
Ethyl ether
Ethyl Hethacrylate
Ethylene dibromide
Ethylenimine
Ethylmethanesulfonate
Ethyl-4,4'-dichlorobenzilate
Etylenebis(dithiocarbamic acid)
Fluoranthene
Fluoroacetamide
Formaldehyde
Formic acid
Furan
Furfural
Glyeidylaldehyde
Heptachlor
Hexachlorobenzene
HexachIorobutadi ene
Hexachlorocyclohexane (a-)
HexachlorocycIopentadi ene
Hexachloroethane
Hexachlorohexahydro-exo,exo-
dimethanonaphthaiene
HexachIoropropene
Hydrazine
Ideno(1,2,3-Cd)pyrene
Isobutanol
Isosafrole
Dominant
Process
B H P V 0
*
*
*
*
* *
*
* *
* *
*
*
*
*
*
*
*
*
* *
*
*
*
* *
*
*
*
*
* *
*
*
*
4-
Half-life
Days
>5; <160
14
205
0.03
0.33
>5; <36
999
31
>5; <29
>5; <83
4.7
4.3
8.1
5.5
>365
6
8.6
11
5
0.8
>7.2; <458
>365
15
999
1.6
237
5.3
0.6
75; <29
0.5
11.0
7.3
>365
0.02
2.6
16
13
>5; <147
3.8
3.4
>5; <55
References
& Comments
1.2,3
1,2,3
1,2,3
6
1.2,3
1,2,3
1,2,3
1,2,3
1,2,3
1,2,3
4
1,2,3
1,2,3
1,2,3
1,2,3
1,2,3
,2,3
,2,3
,2,3
,2,3
,2,3
,2,3
4a
1,2,3
4
1,2,3
1,2,3
1,2,3
1,2,3
4,6
4
4
1,2,3
4a
4
1,2,3
1,2,3
1.2,3
1,2,3
4a
1,2,3
1,2,3
115
-------
TABLE C-l (Continued)
Waste Name
Kepone
Lead
Lindane
Maleic anhydride
Malononitrile
Melphalan
Methanol
Hethapyriline
Methomyl
Methyl aziridine
Methyl Chlorocarbonate
Methyl ethyl ketone
Methyl hydrazine
Methyl iodide
Methyl methacrylate
Methyl parathion
Methylcholanthrene (3-)
Methylene bromide
Methylene chloride
Methylenebis(2-chloroaniline) (4,4'-)
Methyllacetonitrile (2-)
MethylthiouraciI
Methyl-2-pentanone (4-)
Mitomycin C
Naphthalene
Naphthalenedione (1,4-)
Naphthylamine (1-)
Naphthylamine (2-)
Nickel
Nickel carbonyl
Nicotine
Nitrobenzene
Nitroglycerin
Nitrophenol (4-)
Nitropropane (2-)
Nitro-o-toluidine (5-)
n-Nitrosodiethanolamine
N-Nitrosodiethylamine
N-Nitrosomethylvinylamine
N-Nitrosopiperidine
N-Nitrosopyrrolidine
N-Nitroso-di-n-butylamine
Dominant
Process
B H P V 0
Half-life
Days
999
>365
0.0003
>365
>365
2.4
>365
5.2
0.000024
3.3
38
8.7
7.4
90
13
11
6.2
>365
>365
>365
8.0
999
6.2
60
51
5
999
9.9
999
18.8
14
6.4
11
999
256
7.9
4.1
20.0
9.6
References
& Comments
1.2.3
1,2.3
1,2,3
1,2.3
1.2,3
1,2,3
1.2.3
1.2.3
1,2.3
1.2.3
4
1,2,3
1,2.3
1,2,3
1,2.3
1.2,3
1,2.3
1,2.3
1.2,3
1.2,3
1,2.3
1.2.3
1,2,3
1,2,3
1.2,3
1.2.3
1,2.3
1,2,3
1,2,3
1.2,3
1,2,3
6
1.2,3
1,2,3
1.2.3
1.2.3
1.2,3
1.2,3
1.2,3
1.2,3
116
-------
TABLE C-l (Continued)
Waste Name
N-Nitroso-N-ethylurea
N-nitroso-N-methyl urethane
N-Nitroso-N-methylurea
N-Phenylthiourea
OctachIorocamphene
Osmium tetroxide
0-Nitrotoluene
Paraldehyde
Parathion
PCB-1254
PentachIorobenzene
PentachIoroethane
Pentach I oron i t robenzene
PentachIorophenol
Pentadiene (1,3-)
Phenacetin
Phenol
Phenylmercuricacetate
Phorate
Phosgene
Phosphine
Phthalic anhydride
Picoline (2-)
Pronamide
Propanamine (1-)
Propane nitrile
Propane sultone (1,3-)
Propyn-1-o1 (2-)
Pyrene
Pyridinamine (4-)
Pyridine
p-Nitroaniline
Reserpine
Resorcinol
Saccharin
Safrole
Selenium
Silver
Si Ivex
Strychnine
T(2,4,5)
Tetrachlorobenzene (1,2,4,5-)
Dominant
Process
B H P V 0
*
*
*
*
*
*
*
* *
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
it
*
+
Half-life
Days
37
8.7
75
>365
18
18
1.4
13
35
2.0
13
11
14
>365
5.3
150
0.1
2.9
4.0
0.96
3.34
0.002
12.5
38
11
9.3
<365
999
1.3
39
2.0
180
23
5
>365
>1; <27
999
999
999
999
999
14
References
& Comments
1,2,3
1,2,3
1,2,3
1,2,3
1.2,3
1.2,3
5
1,2,3
4
4
1.2.3
1.2,3
1.2,3
1,2,3
1.2,3
1,2,3
4b
6
4
,2.3
.2.3
.2.3
.2.3
,2.3
,2.3
,2,3
,2.3
,2,3
5
1,2,3
4
1,2,3
1,2,3
1,2,3
1.2.3
1,2,3
7
1,2,3
1,2,3
1,2,3
1.2,3
1,2,3
117
-------
TABLE C-l (Continued)
Dominant +
Process Half-life References
Waste Name B H P V 0 Days & Comments
Tetrachloroethane (1,1,1,2-) * 9.8 1,2,3
Tetrachloroethane (1,1,2,2) * 8.6 4
Tetrachloroethene * 7.9 4
Tetrachloroethylene * 9.7 1,2,3
Tetrachtoromethane * 9.2 1,2,3
Tetrachlorophenol (2,3,4,6-) * 12 1,2,3
Tetrahydrofuran * 6.7 1,2,3
Tetranitromethane * 43 1,2,3
Thiofanox * >365 1,2,3
Toluene * 7.9 4
Toluene diamine * 30.0 4
Toluene diisocyanate * 0.002 1
Toluidine hydrochloride (a-) * 32 1,2,3
Toxaphene * 14.2 4
Trichloroacetaldehyde * 9 1,2,3
Trichloroethane (1,1,1) * 7.2 4
Trichloroethane (1,1,2-) * 11 1,2,3
Trichloroethene * 7.2 4
Trichloroethylene * 8.3 1,2,3
Trichloromethyl mercaptan * 11 1,2,3
Trichloromonoftuoromethane * 8.5 1,2,3
Trichlorophenol (2,4,5-) * 45 1,2,3
Trichlorophenol (2,4,6) * 13 4
Trinitrotoluene (2,4,6) 15 4a
Tris(2,3-dibromopropyl)phosphate * 28 1,2,3
Urcil,5[Bis-2-chloromethylamino] * <365 1,2,3
Warfarin * 180 1,2,3
Xylene * 9.0 4
Zinc 999
+ A half-life of 999 days is assigned for elements and substances
with very long half-lives.
1. Wolfe (1985)
2. Environmental Monitoring and Services, Inc. (1985)
3. Estimate using a method similar to that described in ICF
(1984), except that the diffusion coefficients were
estimated using the formula suggested by HydroQual (1982).
The Henry's constants were from EPA (1985).
118
-------
TABLE C-l (Concluded)
Dominant +
Process Half-life References
Waste Name B H P V 0 Days & Comments
4. Environ (1984)
4a. Modified from Environ (1984), the photolysis half-life in Environ
(1984) is for mid-day, near surface situation and is multiplied
by a factor of 30 to represent a daily-average, depth-average
situation with the assumptions of a 2m depth of water and a
diffusion attenuation coefficient of 10 m-1.
4b. Photolysis was one of the dominant processes according to Environ
(9184), however, after the adjustment for a typical surface
water environment as described in 4a, biodegradation becomes
the only dominant process.
5. Modified from Zepp et al., (1984), the literature value is
multiplied by a factor of 30 to represent a daily-average,
depth-average situation with the assumption of a 2m depth of
water and a diffusion attenuation coefficient of 10m-1.
6. Estimated using the oxidation constants given in Mabey et al.
(1982) and assuming peroxy radical conc.=10E-9M,
single oxygen conc.=10E-12M.
7. Callahan et al., (1979)
119
-------
APPENDIX D
LOGARITHM N-OCTANOL-WATER COEFFICIENTS (LOG Pow)
Table D-l presents a range of log P values from a
computerized data base (Technical Database Services, Inc., 1985).
For a limited number of substances found at waste sites, and which
are not included in the computerized data base, MITRE calculated
log P values or found log P values in the literature. These
ow ow
values are presented in Table D-2.
121
-------
TABLE D-l
LOGARITHM N-OCTANOL-WATER COEFFICIENTS
Substance Name
1,1, 1 -TRICHLOROETHANE /EPA/
1,1,2, 2 -TETRACHLOROETHANE
1,1, 2 -TRICHLOROTRIFLUOROETHANE
1,1-DICHLOROETHANE /BPA/
1, 1-DICHLOROETHYLENE/VlNYLIDINE CHLORIDE/
1 , 2 , 3-TRICHLOROBENZENE
1,2,3- TRIMETHYLBENZENE
1,2,4, 5 -TETRACHLOROBENZENE
1 , 2 ,4-TRICHLOROBENZENE
1,2,4- TRIMETHYLBENZENE
1,2,5 , 6-DIBENZANTHRACENE
1,2-DIBROMOETHANE
1,2-DICHLOROETHANE /BPA/
1,2-DICHLOROETHYLENE -CIS
1,2-DICHLOROETHYLENE -TR
1 , 3 , 5-TRIMETHYLBENZENE/MESITYLENE/
1,3,5- TRINITROBENZENE
1,3 -BUTADIENE /BPA/
1 , 3 - DICHLOROBENZENE
1,4- NAPHTHOQUINONE
(Source: Technical Database Services, Inc., 1985)
122
CAS Number
71-55-6
79-34-5
76-13-1
75-34-3
75-35-4
87-61-6
526-73-8
95-94-3
120-82-1
95-63-6
53-70-3
106-93-4
107-06-2
156-59-2
156-60-5
108-67-8
99-35-4
106-99-0
541-73-1
130-15-4
Log Pow
2.49
2.39
3.16
1.79
2.13
3.99
3.66
4.82
4.12
3.78
6.50
1.96
1.48
1.86
2.09
3.42
1.18
1.99
3.38
1.78
-------
TABLE D-l (Continued)
Substance Name
1-BUTENE /BPA/
1-CHLOROBUTANE /BPA/
1 - ETHYL- 1 -NITROSOUREA/ENU/
1 - ETHYL- 2 - METHYLBENZENE
1 -METHYL- 1 - NITROSOUREA
1 - PROPENE , 1 - PHENYL
2,2' -DICHLOROETHYLETHER
2,2, 2 -TRICHLORO- 1 , 1 - ETHANEDIOL/CHLORALHYDRATE
2,3,4, 5 -TETRACHLOROPHENOL
2,3,4,6- TETRACHLOROPHENOL
2 , 3 ,4-TRICHLOROPHENOL
2 , 3 , 4-TRICHLOROPHENOL
2,3,5, 6 -TETRACHLOROPHENOL
2,3, 5 -TRICHLOROPHENOL
2,3, 6 -TRICHLOROPHENOL
2 , 3-DICHLOROPHENOL
2,4,5- TRICHLOROPHENOL
2,4, 6 -TRICHLOROPHENOL
2,4,6- TRINITROTOLUENE
2 , 4-DICHLOROPHENOL
CAS Number
106-98-9
109-69-3
759-73-9
611-14-3
684-93-5
637-50-3
111-44-4
302-17-0
4901-51 3
58-90-2
15950-66-0
15950-66-0
935-95-5
933-78-8
933-75-5
576-24-9
95-95-4
88-06-2
118-96-7
120-83-2
Log Pow
2.40
2.64
-0.15
3.53
-0.16
3.35
1.29
1.61
5.05
4.10
3.51
3.51
4.88
4.56
3.46
2.52
3.72
3.62
1.60
3.30
123
-------
TABLE D-l (Continued)
Substance Name
2,4- DIMETHYLPHENOL
2 , 4-DINITROPHENOL
2 , 4-DINITROTOLUENE
2 , 5 -DICHLOROPHENOL
2,6-DICHLOROPHENOL
2-BUTANONE
2-HEXANONE
2-NITROGUANIDINE
2 - PENTANONE
2 -PICOLINE/2 -METHYL PYRIDINE/
3,3' -DICHLOROBENZIDINE
3,4, 5 -TRICHLOROPHENOL
3, 4 -DICHLOROPHENOL
3-METHIO-4-AMINO-6-T-BU-l,2,4-TRIAZINE-5-ONE
3-METHIO-4-AMINO-6-T-BU-l,2,4-TRIAZINE-5-ONE
4 , 4 ' - 1 - PROPYLIDENE- DIPHENOL/DIPHENYLOLPROPANE
4.4--PCB
4,4'-STILBENEDIOL,A,A'-DIETHYL/DES/
4-AMINOPYRIDINE
4 - NITROQUINOLINE - 1 - OXIDE
CAS Number
105-67-9
51-28-5
121-14-2
583-78-8
87-65-0
78-93-3
591-78-6
556-88-7
107-87-9
109-06-8
91-94-1
609-19-8
95-77-2
21087-64-9
21087-64-9
80-05-7
2050-68-2
56-53-1
504-24-5
56-57-5
Log Pow
2.30
1.50
1.98
3.20
2.34
0.29
1.38
-0.89
0.91
1.11
3.51
4.01
2.86
1.70
1.70
3.32
5.58
5.07
0.26
1.02
124
-------
TABLE D-l (Continued)
Substance Name
6-AMINOCHRYSENE
7 , 12 -DIMETHYLBENZC A) ANTHRACENE
A , A , A - TRI CHLOROTOLUENE
A- CHLOROTOLUENE
A-NAPHTHYLAMINE
A- NAPHTHYLTHIOUREA/ANTU/
ACENAPHTHENE
ACETANILIDE , 4 - ETHOXY/PHENACETIN/
ACETIC ACID
ACETIC ACID, ETHYL ESTER
ACETIC ACID, METHYL ESTER
ACETIC ACID, BUTYL ESTER
ACETIC ACID.PROPYL ESTER
ACETONE
ACETONITRILE
ACETOPHENONE
ACETYLENE /BPA/
ACRIDINE
ACRYLAMIDE
ACRYLIC ACID, BUTYL ESTER
CAS Number
218-01-9
57-97-6
98-07-7
100-44-7
134-32-7
86-88-4
83-32-9
62-44-2
64-19-7
141-78-6
79-20-9
123-86-4
109-60-4
67-64-1
75-05-8
98-86-2
74-86-2
260-94-6
79-06-1
141-32-2
Log Pow
4.98
5.80
2.92
2.30
2.25
1.66
3.92
1.58
-0.17
0.73
0.18
1.82
1.24
-0.24
-0.34
1.73
0.37
3.40
-0.67
2.36
125
-------
TABLE D-l (Continued)
Substance Name
ACRYLIC ACID, METHYL ESTER
ACRYLIC ACID, ETHYL ESTER
ACRYLONITRILE
ADIPIC ACID
ALACHLOR/LASSO/
ALACHLOR/LASSO/
ALDICARB/TEMIK/
ALLYL ALCOHOL
ANILINE
ANILINE, N-METHYL
ANTHRACENE
ARGON /BPA/
AZOBENZENE , 4 - DIMETHYLAMINO
B-NAPHTHYLAMINE
BENZALDEHYDE
BENZENE
BENZIDINE
BENZO(A)PYRENE
BENZOIC ACID
BENZONITRILE
CAS Number
96-33-3
140-88-5
107-13-1
124-04-9
15972-60-8
15972-60-8
116-06-3
107-18-6
62-53-3
100-61-8
120-12-7
7440-37-1
60-11-7
91-59-8
100-52-7
71-43-2
92-87-5
50-32-8
65-85-0
100-47-0
Log Pow
0.80
1.32
-0.92
0.08
3.52
3.52
0.70
0.17
0.90
1.82
4.45
0.74
4.58
2.28
1.48
2.13
1.34
5.97
1.87
1.56
126
-------
TABLE D-l (Continued)
Substance Name
BENZOPHENONE
BENZOTHIAZOLE
BIPHENYL
BROMOBENZENE
BROMOCHLOROMETHANE
BUTANE /BPA/
BUTANOL
BUTOXYETHANOL
BUTYL BENZOATE
BUTYLAMINE
BUTYLBENZENE
BUTYLBENZYLPHTHALATE
BUTYRALDEHYDE
CAPTAN
CARBOFURAN
CARBON TETRACHLORIDE /BPA/
CHLORAMBUCIL/NCS 3088/
CHLOROBENZENE
CHLORODIFLUOROMETHANE/FREON-22/ BPA/
CHLOROFORM
CAS Number
119-61-9
95-16-9
92-52-4
108-86-1
74-97-5
106-97-8
71-36-3
111-76-2
136-60-7
109-73-9
104-51-8
85-68-7
123-72-8
133-06-2
1563-66-2
56-23-5
305-03-3
108-90-7
75-45-6
67-66-3
Log Pow
3.18
2.01
3.95
2.99
1.41
2.89
0.88
0.83
4.21
0.88
4.26
3.97
0.88
2.35
2.32
2.83
1.70
2.84
1.08
1.97
127
-------
TABLE D-l (Continued)
Substance Name
CHLOROTRIFLUOROMETHANE/FREON 13/BPA/
CYCLOHEXANE /BPA/
CYCLOHEXANOL
CYCLOHEXANONE
CYCLOHEXYLAMINE
CYCLOPROPYLBENZENE
CYTOXAN/CYCLOPHOS PHAMIDE/
DDE
DDT
DECANE
DEMETONTHIOL
DI- (P-AMINOPHENYL)METHANE
DI - 2 - ETHYLHEXYLPHTHALATE
DI - I - PROPANOLAMINE
DIBENZOFURAN
DIBUTYL ETHER
DICHLORODIFLUOROMETHANE/FREON-12/BPA/
DICHLOROFLUOROMETHANE/FREON- 2 I/ BPA/
DICOFOL
DIETHANOLAMINE
CAS Number
75-72-9
110-82-7
108-93-0
108-94-1
108-91-8
873-49-4
50-18-0
72-55-9
50-29-3
124-18-5
298-04-4
101-77-9
117-81-7
110-97-4
132-64-9
142-96-1
75-71-8
75-43-4
115-32-2
111-42-2
Log Pow
1.65
3.44
1.23
0.81
1.49
3.27
0.63
4.87
3.98
5.01
1.93
1.59
3.98
-0.82
4.12
3.21
2.16
1.55
3.54
1.43
128
-------
TABLE D-l (Continued)
Substance Name
DIETHYLAMINE
DIETHYLPHTHALATE
DIMETHOATE
DIMETHOXYMETHANE
DIMETHYLAMINE
DIMETHYLFORMAMIDE
DIMETHYLPHTHALATE
DINOSEB
DIOXANE
DIPHENYLAMINE
DIPHENYLNITROSAMINE
DIPROPYLAMINE
DIPROPYLNITROSAMINE
DODECANOIC ACID/LAURIC ACID/
ETHANE /BPA/
ETHANE -1,2- DIOL/ETHYLENE GLYCOL/
ETHANOLAMINE
ETHION
ETHYL CHLORIDE/BPA/
ETHYL ETHER
CAS Number
109-89-7
84-66-2
60-51-5
109-87-5
124-40-3
68-12-2
131-11-3
88-85-7
123-91-1
122-39-4
86-30-6
142-84-7
621-64-7
143-07-7
74-84-0
107-21-1
141-43-5
563-12-2
75-00-3
60-29-7
Log Pow
0.57
2.47
0.50
0.00
-0.38
-1.01
1.56
2.30
-0.42
3.34
3.13
1.73
1.36
4.20
1.81
-1.93
-1.31
5.07
1.43
0.77
129
-------
TABLE D-J. (Continued)
Substance Name
ETHYLAMINE
ETHYLBENZENE
ETHYLENE
ETHYLENE OXIDE /BPA/
FLUORANTHENE
FLUORENE
FLUOROACETAMIDE
FLUOROFORM/BPA/
FORMALDEHYDE
FORMALDEHYDE
FORMIC ACID
FURAN /BPA/
FURFURAL
GLYCEROL /BPA/
GLYCERYL TRINITRATE
HEPTANE
HEXACHLORO -1,3- BUTADI ENE
HEXACHLOROBENZENE
HEXACHLOROCYCLOHEXANE , ALPHA ISOMER//124/356/
HEXACHLOROCYCLOHEXANE , BETA ISOMER//135/246/
CAS Number
75-04-7
100-41-4
74-85-1
75-21-8
206-44-0
86-73-7
640-19-7
75-46-7
50-00-0
50-00-0
64-18-6
110-00-9
98-01-1
56-81-5
55-63-0
142-82-5
87-68-3
118-74-1
319-84-6
319-85-7
Log Pow
-0.13
3.15
1.13
-0.30
5.20
4.18
-1.05
0.64
0.35
0.35
-0.54
1.34
0.41
-1.76
1.62
4.66
4.74
4.13
3.80
3.78
130
-------
TABLE D-l (Continued)
Substance Name
HEXACHLOROCYCLOHEXANE/BHC/ GAMMA ISOMER
HEXACHLOROCYCLOPENTAD I ENE
HEXACHLOROETHANE
HEXACHLOROPHENE /PKA2=11.33/
HEXANE
HYDRAZINE
HYDRAZOBENZENE
HYDROCYANIC ACID /BPA/
I-BUTANOL
I-PROPANOL
I-PROPYLAMINE
IMIDAZOLIDONE , 2 -THIO/ETHYLENETHIOUREA/
INDENE
ISOPROPYLBENZENE
M-CHLOROPHENOL
M- DIHYDROXYBENZENE/RESORCINOL/
M-DINITROBENZENE
M-XYLENE
MALATHION
MALEIC ACID HYDRAZIDE /3 , 6-DIHYDROXYPYRIDAZIN
CAS Number
58-89-9
77-47-4
67-72-1
70-30-4
110-54-3
302-01-2
122-66-7
74-90-8
78-83-1
67-63-0
75-31-0
96-45-7
95-13-6
98-82-8
108-43-0
108-46-3
99-65-0
108-38-3
121-75-5
123-33-1
Log Pow
3.61
5.04
3.82
2.62
3.90
-2.07
2.94
-0.25
0.76
0.05
-0.03
-0.66
2.92
3.66
2.50
0.80
1.49
3.20
2.89
-0.84
131
-------
TABLE D-l (Continued)
Substance Name
METHACRYLIC ACID, ETHYL ESTER
METHACRYLIC ACID, METHYL ESTER
METHACRYLONITRILE
METHANE /BPA/
METHANOL
METHOMYL
METHOMYL
METHOXYCHLOR
METHYL BROMIDE /BPA/
METHYL CHLORIDE/BPA/
METHYL IODIDE
METHYLAMINE
METHYLHYDRAZINE
METOLACHLOR
METOLACHLOR
MORPHOLINE
MUSCIMOL
N.N-DIMETHYLANILINE
N - METHYLCARBAMATE , 1 - NAPHTHYL
N-NITROSODIBUTYLAMINE
CAS Number
97-63-2
80-62-6
126-98-7
74-82-8
67-56-1
16752-77-5
16752-77-5
72-43-5
74-83-9
74-87-3
74-88-4
74-89-5
60-34-4
51218-45-2
51218-45-2
110-91-8
2763-96-4
121-69-7
63-25-2
924-16-3
Log Pow
1.94
1.38
0.68
1.09
-0.64
1.08
1.08
3.31
1.19
0.91
1.69
-0.57
-1.05
3.13
3.13
1.08
-2.39
2.31
2.36
1.92
132
-------
TABLE D-l (Continued)
Substance Name
N-NITROSODIETHYLAMINE
N-NITROSODIMETHYLAMINE
N-NITROSOPIPERIDINE
N-NITROSOPYRROLIDINE
NAPHTHALENE
NITROBENZENE
NITROETHANE
NITROMETHANE
NONANE
0-AMINOPHENOL
0-CHLOROPHENOL
0-CHLOROTOLUENE
0-DIBUTYLPHTHALATE
0-DICHLOROBENZENE
0-DINITROBENZENE
0 - DIOCTYLPHTHALATE
0- ETHYL CARBAMATE/URETHANE/
0-HYDROXYBENZOIC ACID/SALICYLIC ACID/
0-METHYLBENZENESULFONAMIDE
0-NITROPHENOL
CAS Number
55-18-5
62-75-9
100-75-4
930-55-2
91-20-3
98-95-3
79-24-3
75-52-5
111-84-2
95-55-6
95-57-8
95-49-8
84-74-2
95-50-1
528-29-0
117-84-0
51-79-6
69-72-7
88-19-7
88-75-5
Log Pow
0.48
-0.57
0.63
-0.19
3.59
1.85
0.18
-0.33
4.51
0.62
2.17
3.42
4.72
3.38
1.58
5.22
-0.15
2.26
0.84
1.26
133
-------
TABLE D-l (Continued)
Substance Name
0-PHTHALIC ACID
0-TOLIDINE
0-XYLENE
OCTANE
OCTANOL
P-AMINOPHENOL
P-CHLOROANILINE
P-CHLOROBIPHENYL
P-CHLORO PHENOL
P-DICHLOROBENZENE
P - DIHYDROXYBENZENE/HYDROQUINONE/
P-DINITROBENZENE
P-NITROANILINE
P-NITROPHENOL
P-NITROTOLUENE
P-XYLENE
PARALDEHYDE
PARAOXON
PARATHION
PENTACHLOROBENZENE
CAS Number
88-99-3
119-93-7
95-47-6
111-65-9
111-87-5
123-30-8
106-47-8
2051-62-9
106-48-9
106-46-7
123-31-9
100-25-4
100-01-6
100-02-7
99-99-0
106-42-3
123-63-7
311-45-5
56-38-2
608-93-5
Log Pow
0.73
2.34
2.77
5.18
3.15
0.04
1.83
4.90
2.35
3.39
0.59
1.46
1.39
0.76
2.37
3.15
0.67
1.69
2.15
5.52
134
-------
TABLE D-l (Continued)
Substance Name
PENTACHLOROETHANE
PENTACHLORONITROBENZENE/QUINTOZENE/
PENTACHLOROPHENOL
PENTANE /BPA/
PENTANOL
PHENANTHRENE
PHENOL
PHENOL , 4 - CHLORO , 3 -METHYL
PHENOXYACETIC ACID ,2,4, 5 -TRI CHLORO
PHENOXYACETIC ACID , 2 , 4 - DICHLORO
PHENTERMINE
PHENYLARSONIC ACID /PKA2-8 . 48/
PHENYLMERCURIC ACETATE
PHENYLTHIOUREA
PHORATE/THIMET/
PHOSPHINE SULFIDE,TRIS-(1-AZIRIDINYL)/NSC 639
PHOSPHORIC ACID
PHTHALIC ANHYDRIDE
PIPERAZINE
PROARGYL ALCOHOL/2 - PROPYN - 1 - OL/
CAS Number
76-01-7
82-68-8
87-86-5
109-66-0
71-41-0
85-01-8
108-95-2
59-50-7
93-76-5
94-75-7
122-09-8
98-05-5
62-38-4
103-85-5
298-02-2
52-24-4
7664-38-2
85-44-9
110-85-0
107-19-7
Log Pow
3.05
4.22
5.01
3.23
1.40
4.46
1.48
3.10
3.13
2.81
1.90
0.06
0.71
0.73
3.56
0.53
-1.86
1.60
-1.17
-0.38
135
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TABLE D-l (Continued)
Substance Name
PROPANOL
PROPENAL/ACROLEIN/
PROPIONALDEHYDE
PROPIONIC ACID
PROPIONITRILE
PROPYLAMINE
PROPYLENE /BPA/
PROPYLENE OXIDE
PYRENE
PYRIDINE
QUINOLINE
QUINONE
STYRENE
TEREPHTHALIC ACID
TETRACHLOROETHYLENE
TETRAFLUOROMETHANE /BPA/
TETRAHYDROFURAN /BPA/
THIOPHENOL
THIOUREA
TOLUENE
CAS Number
71-23-8
107-02-8
123-38-6
79-09-4
107-12-0
107-10-8
115-07-1
75-56-9
129-00-0
110-86-1
91-22-5
106-51-4
100-42-5
100-21-0
127-18-4
75-73-0
109-99-9
108-98-5
62-56-6
108-88-3
Log Pow
0.30
-0.01
0.59
0.33
0.16
0.48
1.77
0.03
4.88
0.62
2.02
0.20
2.95
2.00
3.40
1.18
0.46
2.52
-0.98
2.69
136
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TABLE D-l (Continued)
Substance Name
TRICHLOROETHYLENE
TRICHLOROFLUOROMETHANE/FREON-11/BPA/
TRIETHYLAMINE
TRIETHYLPHOSPHATE
TRIFLURALIN
TRIMETHYL ORTHOFORMATE
TRIS- (2 , 3-DIBROMOPROPYL) -PHOSPHATE
UREA
VINYL ACETATE
WARFARIN
CAS Number
79-01-6
75-69-4
121-44-8
78-40-0
1582-09-8
149-73-5
126-72-7
57-13-6
108-05-4
81-81-2
Log Pow
2.29
2.53
1.44
0.80
3.06
0.25
3.71
-1.09
0.73
0.05
137
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TABLE D-2
LOGARITHM N-OCTANOL-WATER COEFFICIENTS (LOG POW) FOR SELECTED ORGANIC
SUBSTANCES FOUND AT NATIONAL PRIORITIES LIST SITES
Substance Name
Log Pow
Source
Acenaphthalene
B enz ( A) an. thr acene
Benzo(B)fluoranthene
Benzo(K)fluoranthene
1,12-Benzoperylene
Creosote (coal tar)
Chrysene
Dibenz(A,H)acridine
m-Dlchlorobenzene
Beta hexachlorocyclohexane (Beta BHC)
Delta hexachlorocyclohexane (Delta BHC)
3-Methylcholanthrene
1-Methylphenanthrene
Methylnaphthalene
Napthol
2-Pentanone (Methyl propyl ketone)
2,3-Phenylene pyrene
1,2,3,4-Tetrachlorobenzene
Trlbromomethane (Bromoform)
Trimethyl benzene
2,3,4-Trinitrotoluene (TNT)
2,4,5-Trlnitrotoluene (TNT)
3.74 U.S. EPA, 1981
5.61 U.S. EPA, 1981
6.06 U.S. EPA, 1981
6.06 U.S. EPA, 1981
6.51 U.S. EPA, 1981
3.98 Callahan et al., 1979
4.98 Leo et al., 1971
5.73 U.S. EPA, 1981
3.44 Veith et al., 1980
3.80 Callahan et al., 1979
4.14 Callahan et al., 1979
6.97 U.S. EPA, 1981
5.00 U.S. EPA, 1981
4.22 MITRE*
2.84 Leo et al., 1971
0.84 MITRE*
6.51 U.S. EPA, 1981
4.60 Chiou, 1985
2.39 MITRE*
4.04 MITRE*
2.01 MITRE*
2.01 MITRE*
*Calculated by Leo's Fragment Constant Method as specified in Lyman et al.,
1982.
138
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APPENDIX E
THE SELECTION OF METHODOLOGY IN ESTIMATING PARTITION
COEFFICIENT OF METALS
The HydroQual analysis of field data (Delos et al., 1984)
indicated the absence of pH effect on sorption of priority metals on
natural sorbent in surface water. This finding is contrary to a
wealth of literature which documents the importance of pH on
sorption in surface water.
Since first noted by Kurbatov et al. (1951), the importance of
pH effect on sorption has been progressively recognized. In fact,
pH is generally considered the master variable that governs the
extent of inorganic sorption (Schindler, 1981).
Percent cation and anion adsorption on metal oxides (Dzombak
and Morel, 1985; Leckie et al., 1980; and Benjamin and Leckie, 1981)
and metal adsorption on organics have all been found to strongly
depend on pH. Recall that the partition coefficient (K ) is
defined as:
K _ F _ Solute adsorbed per unit mass or solid
p C Solute remaining in solution
Percent adsorbed / f onnA\~l
= , —-= s (mass of solid;
(100 percent adsorbed)
At a fixed mass of, solids, the increase of the percent adsorption
increases the partition coefficient and the decrease of the percent
adsorption decreases the partition coefficient. Therefore, the pH
effect on the percent adsorption should manifest itself on the
partition coefficient. However, when the field data were analyzed
139
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by HydroQual, no consistent relationship was found between pH and
the partition coefficient.
One plausible cause for the absence of pH effect in the field
data is the presence of organic substance (Morel, 1983). The
presence of natural organic compounds has been suggested to
increase, decrease, or not affect the sorption of metal oxide. In
the absence of sufficient information to predict the effect of
natural organic material on the sorption of metal ions in natural
water, one may consider the data of Davis (1983) on the sorption of
copper on o-Al.O, (Figure E-l).
In the figure, the percent adsorption of copper on alpha-
aluminum oxide is shown for two cases—with and without the presence
of dissolved organic carbon (DOC). The dissolved organic carbon was
extracted from the surface sediment of Lake Urnersee, Switzerland.
In the absence of dissolved organic carbon, the percent copper
adsorbed is characteristic of the cation adsorption on metal oxide—
increasing drastically from 0 percent at pH 4.5 to 70 percent at
pH 7. In the presence of 4.7 mg/1 dissolved organic carbon, the pH
adsorption edge* moves to the left. The percent copper adsorbed
increases from 0 percent at pH 3 to 50 percent at pH 5.5 and
decreases slightly to 40 percent for the pH range of 5.5 to 8.
*The absorption of cations generally increases from nearly 0 to
100 percent over a narrow pH range (1 to 2 pH units). The curve
which shows the dramatic increase of adsorption percentage over the
critical pH range is called the "pH adsorption edge."
140
-------
%Cu (II)
Adsorbed
100
90
80
70
60
50
40
30
20
10
0
3.5
5 x 10~7 M Cu(ll)
50mg/l 7-AI2O3
0.01 M NaCI
DOC Added
Oo
Q 4.7 mg/l
I
4.0
4.5
5.0
5.5
6.0 6.5
pH
7.0
7.5
8.0
8.5
9.0
Source: Davis, 1983.
FIGURE E-1
ADSORPTION OF COPPER ON ALUMINA IN THE PRESENCE
OF NATURAL ORGANIC MATTER
141
-------
The comparison of the two cases indicates that at low pH (i.e.,
pH less than or equal to 6), the organic matter increases the copper
adsorption while at higher pH (pH greater than 6), it decreases the
copper adsorption. The net result is a flattening of the adsorption
curve over the pH range of 5 to 8. If the percent adsorption is
fairly consistent over the range of pH 5 to 8, so is the partition
coefficient. Therefore, the presence of organic matter in the
natural water may be the cause for the lack of pH effect in the
field data analysis.
The gap between the experimental results (of metal sorption on
metal oxides) and their application to natural systems is suggested
by the aforementioned difference between the experimental results
and field data. Most of the experimental studies are on sorption on
metal oxides in the absence of organic matter. Although metal
oxides are important natural sorbents, bare oxide surfaces (i.e.,
hydrated and hydrolyzed but not coated with organic matter) probably
are not the principal sorption sites (Morel, 1983). There is
increasing evidence indicating that organic surfaces, either as
coatings on inorganic particles or as organic matter itself, provide
_2
most of the sorption sites. Bare metal oxides except SiO» are
positively charged near neutral pH (Stumm and Morgan, 1981).
Therefore, the predominance of organic surface is supported by
recent studies indicating that almost all particles in natural
aquatic systems are negatively charged (Davis and Gloor, 1981, and
142
-------
Hunter and Liss, 1979). High surface coverages of organic matter
have been demonstrated for iron oxydroxides precipitated in-situ in
lake water (Tipping, 1981). Hunter (1980) suggested that the
adsorbed organic material could mask the properties of the
underlying solid. However, at present much less is known about
adsorption on organic surfaces than on metal oxide, and to
extrapolate the result from adsorption on metal oxide to account for
the effect of organic surface coating presents considerable
difficulty.
In this study, the HydroQual's result is used because of the
possible lag between the development of theoretical sorption models
from laboratory studies and their application to natural systems.
The HydroQual's result, which indicates that the partition
coefficient is affected only by the suspended solid concentration,
is also used as a screening procedure for metals in rivers and
streams (Mills et al., 1985).
143
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APPENDIX F
TIME OF TRAVEL IN STREAMS AND RIVERS OF
THE SURFACE WATER PATHWAY
The time of travel between two locations in surface water is an
important consideration in evaluating the importance of decay
processes when the decay rates of a substance are known. For
example, if travel time is one day, decay processes with a kinetic
rate of less than 0.1 day are rather unimportant because they
only induce less than 10 percent* concentration difference between
the two locations. In contrast, if the travel time is 20 days, the
process with a kinetic rate of 0.1 day becomes an important
attenuation mechanism because more than 85 percent of the substance
is lost by the time it reaches the downstream location.
Therefore, before proposing a scheme for ranking the
persistence of hazardous organic substances in the surface water
environment, it is necessary to define a time scale of concern.
The time scale of concern is not explicitly defined in the
HRS. Nonetheless, an estimate of the time scale may be made based
on the target distance scale specified in the HRS. In evaluating
the targets for the surface water pathway, the HRS currently uses a
three mile target distance limit. Distance is measured in stream
miles from the probable point of entry of released substance or from
the most downstream point of measured contamination. The time of
*Percent loss = (1 - (exp [-(decay rate) x (travel time)])) x 100%.
145
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travel may then be determined as three miles divided by the stream
velocity.
A three-mile distance corresponds to a relatively short travel
time in most surface water environments. Salomons and Forstner,
(1981) estimate that surface water flow velocity ranges from 101 to
103 cm/sec (0.23 to 23 mph). This suggests a travel time for three
miles ranging from 0.005 to 0.5 days. Table F-l summarizes the
results of several Time of Travel studies conducted by the
U.S. Geological Survey. The flow velocity ranges from 0.16 mph for
the Ohio River from Pittsburgh to Bellaire during a low flow period
to 6 mph in several streams in the Williamette River Basin, Oregon,
during high flow periods. This range of 0.16 to 6 mph flow
velocities corresponds to a range of travel time of 0.021 to
0.78 days for a three-mile distance. Simons (1971) reports that the
U.S. Geological Survey tabulated 2,950 point velocity measurements
and found that fewer than one percent of the measurements exceeded
13 fps (8.9 mph), and that the mean velocity was 4.84 fps
(3.3 mph). The median velocity corresponds to a three-mile travel
time of 0.05 days; it is 0.04 days for the mean velocity.
Based on the information available, 0.1 day is selected as the
representative three-mile travel time in streams and rivers. The
short travel time for streams and rivers clearly suggests that only
substances with half-lives much shorter than one day will experience
significant decay while traveling a distance of three miles.
146
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TABLE F-l
SUMMARY OF TIME OF TRAVEL STUDIES BY U.S. GEOLOGICAL SURVEY
Name of River
Great Miami River
Potomac River
Middle Patuxent River
Little Patuxent River
Patuxent River
Mississippi River
Missouri River
Reach
Dayton to Cleveland, Ohio
Ohio (71.3 miles)
Cumberland, MD to
Washington, DC
(186.1 miles)
Baton Rouge to Plaquemine, LA
Plaquemine to Sunshine
Bridge, LA
Sunshine Bridge to Reserve,
LA
Reserve to New Orleans, LA
Yankton, SD to St. Louis,
MO
Flood Conditions
During the Study
Low stream flow
discharge
(550 cfs In July)
Low flow with 99.9%
exceed ence
High flow with 0.3X
exceedence
Flow in the river is
fairly uniform
Velocity (mob) References
0.28 Bauer, 1968
0.51 Searcy and Davis, 1961
3.4
0.74 Crooks et al., 1967
0.90
0.70
1.44 Stewart, 1967
1.36
1.40
1.24
1.68 - 3.35 Bowie and Petri, 1969
1.34 - 2.32
-------
TABLE F-l (Concluded)
Same of River
Reach
Flood Conditions
During the Study
Velocity (mph)
References
00
Streams in the
Williamette River
Basin, Oregon:
Subreach discharge
for Williamette and
Williamette Rivers
Middle Santiam River
South Santiam River
Ohio River
Pittsburgh to Bellaire
(96.4 miles)
Bellaire to Parkersburg
(88.0 miles)
Parkersburg to Huntington
(127.2 miles)
Huntington to Cincinnati
(158.4 miles)
Low flow 0.4
High 6.0
Low flow 0.2
High flow 6.0
Low flow 0.2
High flow 6.0
Low flow discharge 0.16
High flow discharge 3.75
(404,000 cfs)
Low flow discharge 0.27
(5,375 cfs)
High flow discharge 4.8
(482,500 cfs)
Low flow discharge 0.23
(7,175 cfs)
High flow discharge 4.9
(637,500 cfs)
Low flow discharge 0.34
(9,250 cfs)
High flow discharge 4.4
(822,000 cfs)
Harris, 1968
Steacy, 1961
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APPENDIX G
METHODOLOGY FOR CALCULATING HALF-LIVES
This appendix describes the methodology for calculating the
hydrolysis half-life, the biodegradation half -life, the free-radical
oxidation half -life, the photolysis half -life, and the
volatilization half -life.
G.I Hydrolysis
The hydrolysis half-life (t -./jX. is calculated as follows:
(t1/2)h = 0.693/1^
where K, is the hydrolysis rate constant.
The hydrolysis rate constant K, includes contributions from
acid-catalyzed hydrolysis, base-catalyzed hydrolysis, and
nucleophilic reaction with water (which is often referred to as
neutral hydrolysis). The value of K, is determined as follows
(Lyman et al. , 1982):
Kh = Ka [H+] + Kn + Kb [OH-]
where K^ = Total hydrolysis rate constant, in units of (time)"-'-.
Ka = Acid hydrolysis rate constant, in units of
(M)~l(time)~-l where M is moles per liter.
Kjj = Base hydrolysis rate constant, in units of
KQ = Neutral hydrolysis rate constant, in units of
(time)"1.
[H+] = Hydrogen ion concentration, in units of (M).
[OH+] = Hydroxyl ion concentration, in units of M.
Obtain the values of K , K, , and K from peer-reviewed
a o n
literature or comprehensive review documents such as Wolfe (1985),
Mabey et al. (1982), and Mills et al. (1985). If the hydrolysis rates
149
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are reported for a temperature (T) other than 25°C, multiply the
T-25
reported rates by a temperature adjustment factor of (1.116)
(Wolfe, 1985). This temperature adjustment factor will cause the rate
constant to vary by a factor of 3 for each 10°C change in temperature.
Assume the pH of the water to be in the range of 6 to 9, which
covers most of the pH values in surface water (Britton et al., 1983).
Calculate the value of 1^ at pH 6 (i.e., [H+] = 10~6 M and [OH~] -
10~8 M) and at pH 9 (i.e., [H+] = 10~9 M and [OH~] = 10~5 M).
Select the lower of the two calculated values. Use this as the value of
the total hydrolysis rate constant K, .
G.2 Biodegradation
The biodegradation half-life (ti/?)v is calculated as follows:
(t1/2)b = 0.693/1^
where K, is the biodegradation rate constant, in units of
(time)'1.
Obtain the value of K, from peer-reviewed literature or
comprehensive review documents such as Mills et al. (1985). If the
rate is reported for a temperature (T) other than 25°C, multiply the
25—T
reported value by a temperature adjustment factor of (1.07)
The value of 1.07 is the mean of the lower range 1.04 and the upper
range 1.095 (Delas et al., 1984).
In some cases, the biodegradation rate is specified as a second
order rate constant (e.g., in units of (volume) (cells)
(time)" ), rather than as a first order rate constant (i.e., in
150
-------
unit of (time) ). When a second order rate constant is
specified, multiply the rate specified by an assumed microorganism
concentration of 10 cells/ml* to obtain the value of K. .
G.3 Free-radical Oxidation
Oxidation half-life (t, /0) is calculated as follows:
L/ 2. o
(t1/2)o - 0.693/ko
where K is the total oxidation rate constant.
o
The total oxidation rate includes contributions from oxidation
by peroxyl radicals, oxidation by singlet oxygen, and oxidation by
other unspecified oxidants. The total oxidation rate constant is
calculated as follows (Mabey et al., 1982):
KQ = KRo2 1*0 '] + KlQ2 [102.] + KQX [OX-]
where KRQ = Rate constant for oxidation by peroxyl radical (RO •)•
K10 = Rate constant for oxidation by singlet oxygen (10 •).
= Rate constant for oxidation by other oxldants (OX').
[RO •] = Peroxyl radical concentration.
2
[10 •] = Singlet oxygen concentration.
2
[OX'] = Other oxldants concentration.
Obtain the values of K.., Kln, and 1C from peer-reviewed
KU U OX
literature or comprehensive review documents such as Mabey et al.
-9
(1982). Assume the peroxyl radical concentration to be 10 M and
the singlet oxygen concentration to be 10 M (Mabey et al.,
*This value is roughly the geometric mean of the cell concentration range
of 500 to 106 cells/ml for 40 surface waters as reported by Paris et al.
(1981).
151
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1982). Rate constants for oxidation by other oxidants are rarely
available and need not be included unless available.
G.4 Photolysis
The photolysis half-life (t- ,-) is calculated as follows:
(t1/2)p = 0.693/Kp
where K is the photolysis rate.
The photolysis rate K used in calculating the photolysis
half-life is to be the rate averaged over both a 24-hour day
receiving the mean annual sunlight and the depth of the water body.
Obtain the value of the photolysis rate from peer-reviewed
literature. If the reported value is for a mid-day near surface
situation, multiply the value by 2/Tr* to convert from a mid-day to a
daily average value, and then multiply by 1/30** to convert from near
surface to a depth average value. The value of the photolysis rate
may also be obtained from existing studies that have estimated the
photolysis rate using laboratory data on absorption spectrum and
quantum yield in conjunction with the method specified in Burns
et al. (1982).
*The ratio of daily average to daily-maximum assuming a half
sinusoidal distribution of sunlight over the 12-hour day.
**The ratio of near surface rate to a depth average rate for a water
column of 2 meter depth and light attenuation coefficient of
15 m"1.
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G.5 Volatilization
The volatilization half-life (t/.. ,„) is calculated as
follows:
^1/2^ = °-693/Kv
where K = Volatilization rate, in units of (time)"
Estimate the value of K using the following equation and
parameter values as presented in ICF (1984):
/ i
-1
Kc = 1
v L
[ 1 + RT \
Ko
\
where :
m n
(DC/D°) Hc $ (DC/DW)
11 8 8 8 /
L = Mixing depth of the water body in units of cm; assi
be 200 cm.
K^ = Liquid phase mass transport coefficient of oxygen in the
1 water body in the units of cm hour"1; assumed it to be
8 cm hour"1 in rivers and 1.8 cm hour"-'- in lakes.
D^ = Liquid phase diffusion coefficient of the hazardous
1 substance in water, in units of cm^ sec"1-
D^ = Liquid phase diffusion coefficient of oxygen in water,
1 in units of cm^ sec"-'-.
m = Coefficient depending on the liquid phase turbulence;
assume it to be 0.7.
R = Gas constant, 62.4 torr ("K)"^"1, or
8.205 x 10~5 m3 atm ("K)"1 mol"1-
T = Temperature in unit of °K; assume it to be 298°K.
Hc = Henry's constant in unit of torr M"1 or m3 atm mol"1.
KS = Gas phase transport coefficient for water in units of
cm hour"1; assume it to be 2,100 cm hour"1.
153
-------
D£ = Gas phase diffusion coefficient of the hazardous
substance in air, in units or cm' sec~l-
ifd = Gas phase diffusion coefficient of water in air, in
units of cm^ sec~l.
n = Coefficient depending on the gas phase turbulence; assume it
to be 0.7-
Obtain the value of Henry's constant from peer-reviewed
literature or comprehensive review documents such as EPA (1985). The
ratio of the liquid diffusion constants for the hazardous substance
C 0
and oxygen (D.. /D- ) is related to the ratio of their
molecular weights and is calculated as follows (HydroQual, 1982):
£
D -2/3
where W^ = Molecular weight of hazardous substance.
WQ = Molecular weight of oxygen.
Similarily, the ratio of gas diffusion constants for the
C W
chemical and water (D /D ) is related to the ratio of
g g
their molecular weights and is calculated as follows:
»; IV I18,
where Wy = Molecular weight of water.
154
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APPENDIX H
GLOSSARY
Advection
Biodegradation
First-order Kinetics
Movement of substance by current.
Enzyme-mediated reaction, primarily by
the metabolic activities of bacteria and
fungi; the catalyzed reactions include
oxidation, reduction, hydrolysis.
A reaction where the rate of change of a
substance concentration (c) is only
dependent on the substance concentration,
that is:
Free-radical Oxidation
Fully Mixed Tank Reactor
Half-life
Hydraulic Retention
Time
Hydrolysis
dt
where K is a parameter independent of C.
The oxidation reaction between the
substance with free radicals in water;
the free radicals considered in this
study include singlet oxygen and alkyl
peroxyl radical.
A reactor with no concentration gradient
inside the tank and the outflow concentr
ation is the same as that in the reactor.
The time it takes for the concentration
of a substance be reduced to half of its
initial concentration; it is calculated
as 0.693/(decay rate).
The time it takes for an inflow to fill
up a specific volume of water body,
calculated as V/Q where V is the volume
and Q is the flow rate.
Reaction of a chemical with water;
usually resulting in the introduction of
a dydroxyl into a molecule:
R - X + H20
-*-ROH, + HX
155
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Hydrophobic
Idealized Water Body
Irreversible process
Photolysis
Polarity
Priority Metals
Sorption
Steady-state model
Thermocline
Volatilization
Unionized
Nonwater soluble.
A simplified version of the water body
such as that described in the text: a
stream as a channel with advection as
the dominant transport process and lake
as a fully-mixed reactor.
A reaction which cannot be reversed,
usually proceeds to completion in one
direction.
Photon-activated reaction; molecules
absorb sunlight in ultra violet and
visible portions of the spectrum to gain
sufficient energy to initiate chemical
reaction.
The orientation of a molecule which
cause the separation of the positive
charge nucleus from the negative charged
electron clouds.
Metals on the list of the 129 priority
pollutants designated under the Clear
Water Act, including Sb, As, Be, Cd, Cu,
Pb, Hg, Ni, Se, Ag, Tl and Zn.
A general expression to describe
processes which move a substance from
water to be accumulated in solid; it
includes physical adsorption, chemical
adsorption and ion-exchange.
A mathematical model with describes a
system with constant input and output.
In all lakes of sufficient depth, the
water may be divided into a warm,
turbulent upper region and a cool,
relatively undisturbed lower region.
The plane with maximum rate of decrease
in temperature is defined as thermocline.
Loss of a substance from water to the
atmosphere.
Not ionized; in a nondissociated
molecular form.
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