PB82-256884
Retention and Transformation of Selected Pesticides and Phosphorus in
Soil-Water Systems: A Critical Review
Florida Univ., Gainesville
Prepared for
Environmental Research Lab.
Athens, GA
May 1982
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EPA 600/3-82-060
Hay 1982
P.BS2-256884
RETENTION AND TRANSFORMATION OF SELECTED PESTICIDES
AND PHOSPHORUS.IN SOIL-WATER SYSTEMS:
A CRITICAL REVIEW
Grant No. R-805529-01
Editors
P.S.C. Rao and J.M. Davidson
Soil Science Department
University of Florida
Gainesville, Florida 32611
Project Officer
Charles N. Smith
Technology Development and Applications Branch
Environmental Research Laboratory
Athens, Georgia 30613
ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
ATHENS. GEORGIA 30613
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TECHNICAL REPORT DATA
(Please read lauructions on themtrse before completing)
1. REPORT NO. " 2.
EPA-&00/3-82-060 ORD Report
4. TITLE AMD 9US-TITLB
Retention ami Transformation of Selected Pesticides and
Phosphorus 1n Soil-Water Systems: A Critical Review
S. REPORT DATE ¦
May 1982
B. PERFORMING ORGANIZATION CODE
7. AUTHORtS*
8, performing organization report no.
9. PERFORMING ORGANIZATION NAME AND AOORESS
Soil Science Department
University of Florida
Sainesv11le, Florida. 32611
io. program element no.
AARB1A
11. contract/brant no.
R-805529-01
17.9PONSO«INOJ»a6NCVNAMEAND.ADOnSS3
Environmental Research Laboratory—Athens GA
Office of Research and. Development
;llvSv • Environmental.Rrotection Agency
Athens., Georgia' 306T 3
13. TYPC OPREPORT ANO PERIOD COVEREO
Final:, 11/77-10/79
14. SPONSORING AGENCY CODE
EPA/600/01
."^SUPPLEMENTARY NOTES .
Editors: P.S.C. Rao: and J.M. Davidson
»6. ABSTRACT
The current stater of-the-art for measuring or estimating pesticide retention and
transformation parameters required in nonpoint source pollution models was reviewed. .
A data base of sorption partition coefficients, degradatiln rate coefficients, and
half-Hves for a broad spectrum of pesticides was compiled from a literature survey.
Adsorption partition coefficients normalized with respect to soil organic carbon con-
tent were approximately constant across soils for a given pesticide. Octanol-water
partition coefficients were good predictors of pesticide adsorption parameters. Chem-
ical persistence in soils for a large number of pestlcldes/has been measured under a
variety of soil environmental conditions. These data were used to calculate first-
order decay coefficients and. half-lives. The-variability of these degradation parame-
ters for a given pesticide across several soils was within d factor of two. Multiple
regression equations that correlated degradation (or disappearance) rates with soil .....
properties could not be developed from the iiterature data because of inadequate Infor-
mation regarding soil physical, chemical, and environmental conditions during the
pesticide degradation studies. Seasonal losses by runoff from agricultural fields
were generally less than 0.5 - 1.0 % of the total amount applied. Although pest1ti
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NOTICE
Mention of trade names or commercial products does not
constitute endorsement or recommendation for use.
it
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FOREWORD
Environmental protection efforts are Increasingly directed towards
preventing adverse health and ecological effects associated with specific
compounds of natural or human origin. As part of this Laboratory's
research on the occurrence, movement, transformation, impact and control of
environmental^contaminants, the: Technology. Dev$lopment and, Applications
Branch: develops management and engineering..toolsfor¦ &ssses=s1iifg and con*
trolling adverse environmental effects of nonirrlgated agriculture and
of silviculture.
Surface, anil.groundwaters. may:, under certain conditions, be adversely
affected fcy the presence and/or accumulation of phosphates and pesticides
resulting from, the application of these chemicals to agricultural lands to
maintain current production levels. Because of their'water pollution
potential, it 1s important that we understand their fate in the field and
distribution in the solid and liquid phases leaving agricultural fields
during runoff events.; This report presents, based on an extensive' Wterature
review, first-order degradation rate Coefficients and sorption, partition
coefficients for a large number of pesticides. The coefficients were
evaluated across soils and for different environmental conditions. Transfor-
mation rate coefficients and sorption properties of inorganic phosphate
were also considered and are presented. The coefficients and soil parameters
measured and reported in this manuscript were selected based on their
previous and present use 1n nonpoint source pollution, simulations models
developed for describing retention and transformation of phosphorus and
pesticides within the soil surface and runoff.
David W. Duttweller
Director
Environmental Research Laboratory
Athens, Georgia
iii
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ABSTRACT
The current state-of-the-art for measuring or estimating pesticide reten-
tion and transformation parameters required in non-point source pollution
(NPS) models was reviewed. A data base of sorption partition coeffic:nts,
degradation rate coefficients * and haIf olives for a broad spectrum of
pesticides'was compiled from a'1iterature survey. Adsorption partition
coefficients normalized with respect to soil organic carbon content were
approximately constant across soils for a given pesticide. Octanol-water
partition coefficients were good predictors of pesticide adsorption para-
meters. Chemical persistence in soils for a large number of pesticides has
been measured under a-variety of soil environmental conditions. These data
•were.used to calculate first-order decay coefficients and half-lives. The
variability of these degradation parameters for a given pesticide across
several soils was within a factor of two. Multiple regression equations
which correlated degradation (or disappearance) rates with soil properties
could not be developed from the literature data because of inadequate
information regarding soil physical, chemical and environmental conditions
during the pesticide degradation studies. Seasonal losses by runoff from
agricultural fields were generally less than 0.5 - 1.0% of the total
amount applied. Although pesticide concentrations on the sediment-phase
of the runoff are larger than those in the water-phase, pesticide carried
in the water-phase accounted for greater than 90% of the total mass emission
during a given runoff event.
Phosphate sorption parameters (primarily Langmuir constants) werp
collected from the literature or computed from published adsorption isotherms.
Statistical analysis showed that Langmuir sorption parameters, Smax and k,
each normalized with respect to extractable Fe and Al, were significantly
correlated to the extractable metals. The correlations gave higher R2
values and lower probability levels of significance for oxalate extractable
Fe and Al than for citrate-dithionite-bicarbonate extractions. Correlations
for other parameters with extractable Fe and Al were less significant. The
composition and degree of crystallinity of Fe, Al oxhydroxides appear to *
be the dominant factors in controlling phosphate sorption. Lack of uni-
formity in experimental methods used for determining Langmuir sorption
parameters was noted during the literature survey. Development of standard-
ized methodology (protocols) for this purpose appears essential for
quantification of appropriate sorption parameters.
This report was submitted in partial fulfillment of Grant No. R-805529-01
by the University of Florida under the partial sponsorship of the U.S. Environ-
mental Protection Agency. This report covers the period 1 November 1977 to
31 October 1979, and work was completed as of 31 October 1980.
iv
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CONTENTS
Foreword 1H
Abstract .
Figures v1i
Tables . ix
Acknowledgnents . . . .xvii
1. Introduction , .1
2. Conclusions , . . *. ... • • « • • ..•«•»¦ > .3
3. Reconmenda tions . . . . .5
4. Retention of Pesticides in Soils ..
..Measur-i&g--Nsstic1 7
Time-Dependence ofi.AdsprptionrDesorptloh . . » . . . .11
:Non-S.i.n9ularity of Ads.arption-Pesorption . . . .13
Estimation of Adsorption Partition Coefficients .'. .16
Influence orf Soil Organic Carbon .... . . . . . . .16
Octanbl-Master Partitioning . v . . .. . . . . . . . . ^9
Effects of Soil-Particle Size. .. ...... .. . . . .. . . . .27
Pesticide Losses in Runoff ............... .28
Summary 30
5. Pesticide Transformations in Soils
Aerobic and Anaerobic Degradation ...... .40
Quantitative Aspects of Pesticide Transformations . . . .41
Estimating Pesticide Degradation and Mineralization Rates.44
Herbicides .45
Insecticides . . 52
Fungicides . . ... . . . . . . . . . . . . . . .56
Summary . . . . . . . . . . . . . . . . . . . . . v57
6. Partitioning of Inorganic Phosphate in Soil-Water Systems .
Introduction ... .. . . . . .. ............... .. ¦» . . 74
Models for Equilibrium Sorptfon-Desorptlbh of Phosphate .79
Correlation of Phosphate Sorption Parameters and Selected
Soil Properties . . 85
Estimated Partition Coefficients for Phosphate . . . . ; .104
Laboratory Measurement of Phosphate Sorption. Parameters .113
Models for Time-Dependence of Phosphate Sorption-
Desorption . .116
Mechanisms of Phosphate Sorption . . . . i . ... . . i .127
Thermodynamics of Phosphate Sorption Processes ... . . .131
Summary . . . . . J 133
v
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Literature Cited .134
Appendices
A. Tables of Pesticide Adsorption Isotherm Parameters 158
B. Tables of Pesticide Transformation Rate Coefficients 200
C. Tables of Phosphate Sorp-tion Parameters 268
vi
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FIGURES
Number Page
4-T Graphical representation of the error introduced by the assump-
tion of linearity when the adsorption isotherms are nonlinear.
The. numbers on the lines are the values of Freundich constant
N (see Eqs. 4-4 and 4-8) , . . . ... . . . .10
4-2 Errors introduced by the assumption that adsorptton-desorptlon
isotherms are -singular.when- they are .nonslngular (see Eqs. 4-20,
4r?l) . . ... . . , . .17
4-3 RS1 ationsni p 'between • Koc affd Kqw values for*|test1cide'$ reported
in the literature 26
6-1 Inorganic orthophosphate spfeciation in Aqueous solutions as a
function of. pH . . . ... . . .1 ......... .7.7
6*2 Solubil i ty. tMiagrara fotf- Selfitted solid . phosphate: phases '-(Stumm
and Leckle, 1971) . . . . .... . . . . . . . . . .92
6-3 Relationship between Langmulr k normalized with respect to CDB
extractable Fe + Al and CDB extractable Fe + A1 for selected
soils ..93
6-4 Relationship between normalized Smax and COB extractable Fe + Al
for selected soils ....... . . .. . . V .... . . . . . . . . . .94
6-5 Relationship between Ink and InSmax fo^ selected soils. Numbers
refer to REF 1n Table 6-2 , . . . . .... . . . .... . . . .96
6-6 Relationship between InSntax anct In CDB (Fe + Al) for selected
soils. Numbers refer to REF In Table 6-2 . . . ... . . .... .97
6-7 Relationship between IntSmax/fCDB Fe + Al)] and 1n(CDB Fe + Al):
for selected soils. Numbers refer to REF In Table 6-2 . . . . . .98
6-8 Relationship between IntS^ax/foxFe + Al)] and ln(oxFe + Al) for
selected soils. Numbers refer to ftEF in Table 6-2 . . . 99
6-9- Relationship between Ink and In(oxfe) for selected-soils:
Numbers refer to REF in Table 6-2 . ^ .100
6—1-0: Relationship, between .Ink arid ln(oxFe. + A.l.) for. selected soils-
Numbers refer to REF in Table 6-2 . ...... ..... , . . .101
v1i
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6-11 Relationship between ln(k/oxFe) and ln(oxFe) for selected
soils. Numbers refer to REF in Table 6-2
6-12 Relationship between ln[k/(oxFe + A1)] and ln(oxFe + A1) for
selected soils. Numbers refer to REF in Table 6-2 .
6-13' Phosphate sorption isotherms for isotherms 5 and 49 (Table A6-4'\
Solid lines were computed from S = kSmaxC using the parameters
indicated in the figure 105
6-14 Degree of error in using S1 = k^axC compared to the Langmuir
form, S = kSmaxC/(l + k£)» as a function of equilibrium phos-
phate concentration for various values of k .107
6-15 Relationship of the approximate expression for K[)(=kSm^x) and
CDB Fe + A1 for selected soils. Numbers refer to REF in
Table 6-2 103
6-16 Relationship of .the.approximate expression (Kn = kS^v)
normalized with respect to CDB Fe + A1 and CDB Fe + AT for
selected soils. . Numbers refer to.REF in Table 6-2 109
6-17 Phosphate sorption-desorption isotherms for a soil incubated in
the presence of phosphate (Barrow and Shaw, 1975) . . .110
viii
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TABLES
No. Page
4-1 Summary of Adsorption Partition Coefficient Values Compiled
from Published Literature for Several Pesticides and Related
Organic Compounds . . . . .20
4-2 Summary of Octanol-Water Partition Coefficients,(Kw) for
Pesticides Compiled from Literature. . .... .... ..... .23
4-3 Adsorption Partition Coefficients (l4 ami IW) for Various
Particle-Size fractions of Hickory Hill Sediment.
(Adapted from Karidchoff and Brown, 1978).,. . . . . . . „ . . .29
4-4 Influence of Kq and ps on the Pesticide Lost in the Water-
Phase of the Runoff. Values Shown are % of the Total Loss . . . .29
5-1 Common And Chemical Names of Selected Pesticides . . ..... ..... . .....46
5-2 Degradation Rate Coefficients and Half-Lives for Several Pesticides
under Laboratory and Field Conditions 58
5-3 Grouping of Pesticides Based on their Persistence* 1n Soils under
Laboratory Incubation Conditions . .... . . * •. . . . . . . . .61
6-1 Assumptions Underlying the Derivatlons.pf Adsorption Equations . .80
6-2 Sunmary of phosphate sorption parameters ana soil chemical
properties used 1n linear regression analysis . .. . .87
6-3 Summary of means, standard deviations, and coefficients of varia-
tion of sorption parameters and extractable Fe and A1 89
6-4 Sunmary of estimates obtained from linear regression correlations
of phosphate sorption parameters and extractable Fe and A1 . . . .95
6-5 Effects of time of desorption and solution/soil ratio during
desorptlon on Kq values obtained on a soil previously incubated
with phosphate ........... ill
6-6 Rate constants and activation energies for indigenous feftosphate
release from Thiokol silt loam.* . . . . . . . . .119
6-7 Rate constants of phosphate adsorption by CaCfl^ and, Carfcaol/in.ite 121
ioc
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No.
6-8 ¦ Observed rate constants for the disappearance of phosphate from
solutions in the presence of kaolinite and o Al^O^ at 25 3C ... .1^4
6-9 Values obtained when Eq. (3-50)* was fitted to the changes in
concentration of phosphate when soils were incubated at a range
of temperatures
A1 Adsorption Isotherm Parameters (K, N, Kg and KqC) for Ametryne
and selected soil properties' compiled from the literature. .
A2
A3
A4
Adsorption Isotherm Parameters (K, N, Kg and IW) for Ami ben
and selected soil properties compiled from the literature 160
Adsorption Isotherm Parameters (K, N, Kq and Kg.) for Atrazine
and selected soil properties compiled from the literature. . . . J61
Adsorption Isotherm Parameters (K, N, Kq and Kq^) for Carbofuran
and selected soil properties compiled from the literature 163
A5 Adsorption Isotherm Parameters (K,..N, Kg and KqC) for Chlorobro-
muron and selected soil properties compiled from the literature. .163
A6 Adsorption Isotherm Parameters (X,"NV Kq and Kqc) for Chloxoxuron
and selected soil properties compiled from the literature 164
A7 Adsorption Isotherm Parameters (K, N, Kq and Kq.) for Chlorthiamid
and selected soil properties compiled from the literature 164
Adsorption Isotherm Parameters (K, N, Kq and K^) for Cis-Telone
and selected soil properties compiled from the literature
A8
A9 Adsorption Isotherm Parameters (K, N, Kq and KqC) for Dicamba
and selected soil properties compiled from the literature 165
A10 Adsorption Isotherm Parameters (K, N, Kg and KgC) for Dimethyla-
mine and selected soil properties compiled from the literature . .166
All Adsorption Isotherm Parameters (K, N, Kq and Kqp) for Dipropetryn
and selected soil properties compiled from the literature 166
Adsorption Isotherm Parameters (K, N, Kq and KqC) for Disulfoton
and selected soil properties compiled from the literature 157
A12
A13 Adsorption Isotherm Parameters (K, N, Kg and KqC) for Diuron
and selected soil properties compiled from the literature 168
A14
Adsorption Isotherm Parameters (K, N, Kg and KqC) for Fenuron
and selected soil properties compiled from the literature 172
x
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fto. Page
A15 Adsorption Isotherm Parameters (K, N, Kq and Kqc) for Lindane
and selected soil properties compiled from the literature. . . . .172
A16 Adsorption Isotherm Parameters (K, N, Kq and Kgr) for Linuron
and selected soil properties compiled from the literature. . . . .173
A17 Adsorption Isotherm Parameters (K, N, Kq and Kqc) for Malathion
and selected soil properties compiled from the literature 175
A18 Adsorption Isotherm Parameters (K, N, Kq and KqC) for Methyl
Parathion and selected soil properties compiled from the
literature . 176
A19 Adsorption Isotherm Parameters (X, N'» Ko and Kgg j for Methyl Urea
and selected soil properties compiled from the literature.. . .... .176
A20 Adsorption Isotherm Parameters (K, N, Kn and KqC.) for fletobro-
muron and selected soil properties compiled from the literature.. .177
A2T Adsorption Iiotherm Parameters (K, N, Kq and IW) for Mono! inuron
and selected soil properties compiled from the literature. . . ~ .178
A22 Adsorption Isotherm, Parameters (K, N, Kq and Kqc) for Meburon
and selected soil properties compiled from the literature. . . . .179
A23 Adsorption Isotherm Parameters (K, N, Kq and K^) for p-Chloroanl-
line and selected soil properties compiled from the literature . .179
A24 Adsorption Isotherm Parameters (K, N, Kq and Kqc) for Parathion
and selected soil properties compiled from the literature. . . . .180
A25 Adsorption Isotherm Parameters (K, N, % and Kqt) for Phenyl Urea
and selected soil properties compiled from the literature. . . . .180
A26 Adsorption Isotherm Parameter's-£K, Ny Kb and Koc) for P1c lor am
and selected soil properties compiled from the Titerature. . . . .181
A27 Adsorption Isotherm Parameters (K, N, Kq and K^) for Promethone
and selected soil properties compiled from the literature 182
A28 Adsorption Isotherm Parameters (K, N, Kq and K^) for Prometryne
and selected soil properties compiled from the literature 183
AZ9 Adsorption Isotherm Parameters (K, N, Kq and IW) for Propazlne
and selected soil properties compiled from.the Titerature. . . . .185.
A30 Adsorption Isotherm Parameters (K, N, Xq and IW) for Simazine
and selected soil properties compiled from the literature. . ; . ,187
xi
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No.
A3! Adsorption Isotherm Parameters (K, N, Kq and K^) for Terbacil
and selected soil properties compiled from the literature 193
A3~2 Adsorption Isotherm Parameters (K, N, Kq and KqC) for Thimet
and selected soil properties compiled from the literature 1^3
A33 Adsorption Isotherm Parameters (K, N, Kq and Koc) for trans-telone
and selected soil properties compiled from the literature 194
A34 Adsorption Isotherm Parameters (K, N, Kp and Kqq) for Trithion
and selected soil properties compiled from the literature 1[K
A35 Adsorption Isotherm Parameters (K, N, Kg and Kgr) for 2,4-D acid
and selected soil properties compiled from the literature 195
A36 Adsorption Isotherm Parameters (K, N, Kg and KqC) for 2,4-D amine
and selected soil properties compiled from the literature. . . . .196
A37 Adsorption Isotherm Parameters (K, N, Kq and KoC) for 2,4,5-T
and selected soil properties compiled from the literature 196
A38 Adsorption Isotherm Parameters (K, N., Kg and KqC) for Denobil
and selected soil properties compiled from the literature 197
A39 Article Number used in Tables Al-38 and the corresponding
literature citation 199
B1 Solvent extractable 2,4-D disappearance rates in laboratory
incubated soils under aerobic conditions 201
B2 Solvent extractable 2,4-D disappearance in the field 202
14
B3 Mineralization rates of C-ring labeled 2,4-D in soils under
aerobic conditions 203
B4 Solvent extractable 2,4,5-T disappearance rates in soils incubated
in the laboratory under aerobic conditions 204
.B5 Solvent extractable 2,4,5-T disppearance rates under field
conditions . . . . 205
B6 Solvent extractable atrazine disappearance rates under field
conditions 206
B7 Solvent extractable simazine disappearance rates in the field . .207
B8 Solvent extractable atrazine disappearance rates in soils incubated
in the laboratory under aerobic conditions 208
xii
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Wo. Page
B9 Solvent extractable simazine disappearance rates 1a soils under
aerobic laboratory Incubation . . . . . . . . .... ..... . . . .209
14
BIO Mineralization rates In soils from ring-labeled C-atrazlne under
aerobic conditions . . ¦•¦'. 210
Bll Solvent extractable trlfluralin disappearance rates In soils
Incubated In the laboratory under aerobic conditions 211
B12 Solvent extractable trtfluralin disappearance rates In soils
incubated in the laboratory under aneroblc conditions ...... .212
B13 Solvent extractable trlfluralin disappearance rates in the field . .213
B14 Solvent extractable brpmac 1.1 disappearance rates in soils incubated
In the laboratory under aerobic conditions . . . . . . . . ... . .214
BT5 Solvent extriretable terbac.il • disappearance rates insoite incubated
in the laboratory under aerobic conditions . . . . ..... . . . .215
B16 Mir»era11tatioh for bratotiliAsoils umlSf aertftJic condition? . . . 216-
.B1.7 MineralizatirCm.rates. for terbacl.l in soils under aerobic:
conditions . •,... . . . .... . . .. . .... ...... « . . . . . . ... . .217
B18 Solvent extractable bromacil disappearance rates 1n the field . . .218
B19 Solvent extractable terbacil disappearance rates 1n the field . . .219
B20 Solvent extractable Unuron disappearance rates 1n soils incubated
in the laboratory under aerobic conditions ... . . . . . . . . . .220
B21 Solvent extractable llnuron disappearance rates 1n the field ... .221
B22 Solvent extractable diuron disappearance, rates in the field . .'¦.-.222
B23 Solvent extractable dlcamba disappearance rates in soils Incubated
in the laboratory under aerobic conditions . . . . . .223
B24 Solvent extractable dlcamba diseppearance rates In the field . . . .225
B25 Solvent extractable picloram disappearance rates in soils incubated
in the laboratory under aerobic conditions ............. . 226
B26 Mineralization rates for carboxy-1-labeled picloram In soils
under aerobic conditions . . . . . . . . ..... . . . . . . . . .228
B27 Solvent extractable picloram disappearance rates in the field . . .230
*1.11.
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No. Pa25
B28 Solvent extractable dalapon disappearance rates in soils under
laboratory aerobic incubation 231
B29 Solvent extractable TCA disappearance rates in soils incubated
in the laboratory under aerobic conditions 232
B30 Solvent extractable TCA disappearance rates in the field .233
B31 Solvent extractable'glyphosate disappearance rates in soil under
greenhouse conditions. ... .234
B32 Mineralization rates for'glyphosate in soils incubated in the
laboratory under aerobic incubation 235
B33 Solvent extractable parathion disappearance rate in soils under
laboratory aerobic incubation 236
B34 Solvent extractable parathion disappearance rates in the flooded
soils incubated in the laboratory 237
B35 Solvent extractable parathion disappearance' rates in'the field . . .238
B36 Solvent extractable methyl parathion.disappearance'rates in soils
incubated in the laboratory under aerobic conditions 239
B37 Solvent extractable diazinon disappearance rates in soils incubated
in the laboratory under aerobic conditions 240
B38 Solvent extractable diazinon disappearance rates in flooded soils
incubated in the laboratory 241
B39 Solvent extractable fonofos disappearance rates in the field
(complex first-order) 242
B40 Solvent extractable fonofos disappearance rates in the field
(simple first-order) 243
B4-1 Solvent extractable malathion disappearance rates in soils
incubated in the laboratory under aerobic conditions 244
B.42 Solvent extractable phorate disappearance rates in soils
incubated in the laboratory under aerobic conditions 245
B43 Solvent extractable phorate disappearance rates in the field . . . .246
B44 Solvent extractable carbofuran disappearance rates in soils
incubated in the laboratory under aerobic conditions 247
B45 Solvent extractable carbofuran disappearance rates in flooded
soils 248
xiv
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No. Page
B46 Solvent extractable carbofuran disappearance rates 1n the field . .249
14
B47 Mineralization rates of C-labeled carbofuran In soils under
aerobic conditions . .................. 250
B48 Solvent extractable carbaryl disappearance rates In soils
incubated 1n the laboratory under aerobic conditions 251
B49 Solvent extractable carbaryl disappearance rates 1n the field . . .252
B50 Solvent extractable DDT disappearance rates 1n the field 253
B51 Sol vent extractabl e KIT. di sappearance .rates In f looded or anaerobic
soils incubated 1n the laboratory 255
B52 Solvent extractable aldrin and dleldrln disappearance rrates In
the field i ¦. ». . . .« ¦ « • • . . « «. • «.;« ¦ i*, ¦ . • ! . »¦» .256
B53 Solvent extractable aldrin and dleldrln disappearance rates In
soils incubated 1n the laboratory under aerobic conditions .... .257
B54 Solvent extractable endrin disappearance rates In the field . . . .258
B55- Sol vent: axtraitable endrln disappearance »ate -fb\ flooded ;soils. ..
under laboratory Incubation conditions ....... .259
B56 Solvent extractable chlordane disappearance rates In the field . . .260
B57 Solvent extractable heptachlor disappearance rates 1n the field . .261
B5& Solvent extractable heptachlor disappearance rates 1n soils under
laboratory aerobic incubation . . . ... . . . ........ . .262
B59 Solvent extractable lindane disappearance rates in the field . . . .263
B60 Solvent extractable lindane disappearance rates in soils Incubated
under aerobic conditions 264
B61 Solvent extractable lindane disappearance rates.in flooded soils
1n laboratory studies . . . .265
B62 Solvent extractable PCP disappearance rates In flooded soils . . . . 266
B63 Solvent extractable PCP disappearance rates in soils incubated in
the laboratory under aerobic conditions .... 267
CI Correlation coefficients between sorption maxima and selected
soil properties, ty Ballaux and Peaslee (1975) . . . . .... . . . . 269
xv
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No. Ps"e
C2 Correlation coefficients between phosphate sorption parameters
and soil properties taken from Vijayachandran and Harter (1975). . .ci{)
C3 Phosphate sorption correlated with extractable A1 and Fe by
Williams et al. (1958). . . cl\
C4 Regression equations resulting from correlations of phosphate
sorption and Tamm extractable Fe or Al (Williams et al., 1968) . . .272
C5 Correlation coefficients of phosphate sorption parameters versus
physical-.and chemical properties of the soils, their clay frac-
tions, and bottom sediments used by McCallister and Logan
(1958) . . 273
C6 Correlation and regression coefficients for phosphate sorption
and properties for the tropical and British soils (Lopez-Hernand
and..Bur.uham., 1974) .274
C7 Correlation coefficients and regression equations between phos-
phate retention and soil properties for A and B horizons
(Sanders, 1965) . .275
C8 Regression equations of phosphate retention on aluminum and iron
values for soil groups.(Saunders, 19§5) . . . . . .276
C9 Correlation coefficients for soil groups between phosphate
retention"1' and aluminum and iron values (Saunders, 1965) 277
CIO Langmuir constants published in literature 278
Cll Description of soils used by Ballaux and Peaslee (1975) 285
C12 Description of soil used by Vijayachandran and Harter (1975) . . . .28f>
C13 Description of soils used by Syers, et al. (1973) 287
C14 Description of soils-used by El-Nennah (1975) 288
C15 Description of soils used by Holford et al. (1974) 289
CI6 Description of soils used by Myszka and Janowska (1973) 290
C17 Description of gels used by Rajan and Perrott (1975) 291
C18 Description of gels used by Rajan (1975) 292
CI9 Description of limestones used by Holford and Mattingly (1975) . . .293
C20 Description of soils used by Weir and Soper (1962) 294
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No. Page
C21 Description of soils and sediments used by McCallister and Logan
(1973) . ... .295
C22 Regression parameters from phosphate adsorption isotherms
IS
using S = S - ^ (^-) as the regression model. (S^ and 1/k)
are regression coefficients) 296
C23 Descriptions of soils and experimental parameters used by Minns
and Fox (1976) from whose isotherms Langmuir parameters given
in Table A3-4 were computed 299
C24 Description of soils awl experimental parameters used .by Hoiford
and Mattlngly (1976) and Russell (1963) from whose isotherms
Langmuir parameters were computed . . . . . > . . . . .300
G25 Experimental, .parameters used by Hope arid Syers (1976) from
whose' 1 sothienns Lan^iiftiiy'pirantieters were cwrtputed: ... . . . . . . » .301
C26 ExpeHrterttal;: parameters used by ..Si ngh.and.Tabatabal (1976) from"
whose Isotherms Langmuir parameters were computed . ...¦-... . . .302
C27 Experimental parameter used by Edzwald et. al ; (-19:76:): from whose
Isotherms Lahgmulr parameters were computed; , ...... .303
C28 Experimental parameters used by Barrow (1972) from whose
isotherms Langmuir parameters were computed ... , . . . . . . . .304
C29 Experimental parameters used by Ryden at al. .(1977a,b) from whose
Isotherms Langmuir parameters were computed ..... . .305
C30 Experimental parameters used by Ryden aind Syers (1975) from whose
Isotherms Langmuir parameters.were computed . . ... .306
C31 Data, used for calculating Langmuir constants (listed in
Table A3-4) from isotherms . . . . ... . . ... . . . . 309
C32 Freumllich constants found-in ,literature .. .. .^ . . . . . . ... ., .321
xvii
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ACKNOWLEDGEMENTS
The authors are indebted to Dr. P. V. Rao, Statistics Department, Univer-
sity of Florida for his assistance in statistical analyses of the data pre-
sented in this report. The following members of the Soil Science Department,
University of Florida provided technical assistance in data collection and
analyses: Mr. R. E. Jessup, Mr. D. P. Kilcrease, Mr. D. Forbes, and
Mrs. Rupei-Shu Li. Computer retrieval of the pesticide and phosphorus liter-
ature was accomplished with the assistance of Mr. G. T. Kovalik, Hume Library,
University of Florida. Expert typing of the draft and final versions of this
report was done by Mrs. Katherine B. Williams. Special thanks are extended
to Mr, C. N. Smith and Mr, L, A.. Mulkey of Environmental Research Laboratory,
USEPA,"Athens',*'GA. for over-all•'project coordination and guidance.
The project investigators wish to express their appreciation to the
Center for Environmental Programs in the Institute of Food and Agricultural
Sciences, University of Florida for partial financial support during the pro-
ject period. The project investigators are also indebted to their colleagues
in the Department of Soil Science and the Department of Food Science and
Human Nutrition, University of Florida for their assistance and suggestions
during the development of this report.
xviii
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SECTION 1
INTRODUCTION
The Federal Water Pollution Control Act Amendments of 1972, Public Law
No. 92-500, specifies that the Administration of the Environmental Protec-
tion Agenty shall, 1n cooperation with other agencies, provide guidelines
for. identifying arid-evaluating the nature and extent of nonpotnt. pollution
sources. Because fertilizers and pesticides play such a major role in
todays agriculture, runoff from fields Involved with agricultural production
has long been suspect of being a major ncmpoi-nt pollution source. " Although
i t is diffiailt to conceive of a situation In which, all posslble- environ-
merrtal risks associated with the; use of agricultural c^CTicalS- couW- be
eliminated, management practices cart be used that wlTl significantly reduce
these risks.. Nonpo-int agricultural pollutants of primary concern are sedi-
ment, nitrogen, phosphorus, and pesticides. The Tatter two poMutants can
be transported from an agricultural field by bath the water and sediment
phases.
Several models (stochastic, aitfrtrlca] anra deteiurtnistic) exist for
estimating water and sediment transport from small fields and watersheds.
More than 45 years of erosion research by the U.S. Department of Agriculture
1n cooperation with state agricultural experiment stations has resulted in
the development of numerical relationships for estimating annual soil losses
from fields. Because of the success of these.models and their previous
calibration for specific regions, most agricultural chemical transport
models were developed by"piggybacking" the components for chemical transport
to the hydrologic and sediment transport models. The sediment and agricul-
tural transport models were developed in order to simulate the impact of
agricultural production on water quality. The models also have the potential
to be used by state and local agencies 1n developing and/or identifying
land use management practices that will provide the least risk to the
environment.
Many of the existing chemical transport simulation models have been
calibrated to describe the behavior of a given plant nutrient or pesticide
at a given location and for a specific cultural system. The feasibility
of continuing to calibrate the simulation models for a wide range of
chemicals and management practices is not practical. Therefore, general
relationships for estimating the basic coefficients required to describe
adsorption and transformations of agricultural chemicals in the soil surface
region subject to erosion.are needed. Also the confidence that can be
attached to the independently measured or estimated, coefficients used in
the chemical transport models for describing adsorption and transformation
processes must be quantified.
1
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Numerous equilibrium adsorption studies have been conducted using
various pesticides and phosphorus sources as well as different soils. The
validity of the equilibrium adsorption assumption based on relatively shcrt
term experiments (less than 72 hours) and the reversibility of the adsarr-
tion-desorpticn process has been questioned by several researchers. Adsorp-
tion associated with short term laboratory experiments may not be relevant
for the long contact periods encountered under natural field conditions.
Also, recent experiments involving "bound" pesticide residues point out zhc.
problem associated with assuming reversible adsorption, especially that
occuring during sediment and water transport from an agricultural field r.r
watershed. The bound pesticide residue question suggests that some c; t'u:
pesticide transformation or disappearance data available in the literature
may be in error.and not suitable for estimating transformation rate
coefficients of the original parent compound.
The primary emphasis of the present report will be to present an
extensive and reliable data base of the principal coefficients for describ-
ing adsorption and transformation characteristics of phosphorus and a
broad spectrum'of pesticides used across a range of soil types. This infor-
mation was obtained from an extensive .literature search using various
computer information retrieval packages (data banks such as CANE, BIOS IS,
etc.). The dependence of these retention and transformation coefficients on
selected soil properties was evaluated. The information presented in this
report would be helpful in estimating the values of the retention-and trans-
formation parameters required in various non-point source pollution models.
2
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SECTION 2
CONCLUSIONS
1. A large data base exists for estimating partition coefficients for pesti-
cide retention in soils. An analysis of these data indicated that
errors associated various simplifying assumptions (e.g., linear and sin-
gular isotherms; instantaneous equilibrium) appear to be within a factor
of 2 or 3. Such errors may be tolerable for most nonpoint source pollu-
tion modeling applications.
2. For a given pesticide, adsorption partition coefficients based on Soil
organic carbon were fairly constant regardless of soil type. Further-
more, octanol?water partition coefficients Were-good predictors of pesti-
cide adsorption partition coefficients.
3. Persistence 1n soils of a Urge number of pesticides under a broad range
of soil environmental condition has been reported. A data base was com-
piled for first-order decay constants (k.) and hal.f-1 ives (t, >?.) for pes-,
ticide disappearance it) soils. '
Over the wide range in soil and environmental conditions under which de-
gradation was measured, the coefficient of variation of the average k
and t-j/2 va1ues for a given pesticide was surprisingly small ( 1Q0 days). Pesti-
cides in the first. group are 2,4-D, 2,4,5-T, d.icamFa, parathion^ methyl
parathion, and malathion. Moderately persistent pesticides are atrazine,
simaztne» trifluralin, diuron, terbacil, carbaryl^ and carbofuran. Most
chlorinated hydrocarbon pesticides, were grouped as persistent.
3
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7. Formation of "bound pesticide residues" confounds the problem of estimat-
ing pesticide degradation rates. Differentiation must be made between
•the rate constants for (i) disappearance of parent compound and (ii) pes-
ticide mineralization. The first rate constant does not take into account
formation of bound residues or accumulation of metabolites, while the
second rate constant represents a total breakdown of the pesticide mole-
cule. Therefore, half-lives based on parent compound disappearance are
generally larger than those based on pesticide mineralization.
8. Seasonal pesticide losses by runoff from agricultural fields, in general,
are less than 0.5% of the amount applied. Although pesticide concentra-
tions in the sediment-phase are larger than those in the solution-phase,
pesticide carried in the water accounts for >90% of the total loss for a
given runoff event; exceptions to this generalization are highly sorbed
pesticides (e.g., diquat, chlorinated hydrocarbons) and runoff with high
sediment loads.
9. A broad.range of Langmuir isotherm parameters were compiled for phosphate
sorption by soils and other solid adsorbents. Based upon limited amount
of data available, the sorption parameters were found to be significantly
correlated with extractable ("active") Fe and A1.
10. A lack of uniformity in experimental methods used in determining the
Langmuir sorption parameters or phosphate sorption indices was noted.
Development of standardized nethodology (or protocols) for this purpose
appears to .be essential for .quantification of phosphate sorption param-
eters.
11. "Active" Fe and A1 appear to be measured by oxalate extraction rather
than by citrate-dithionite-bicarbonate extraction. Crystal!inity of Fe
and A1 oxyhydroxides play a dominant role in determining inorganic phos-
phate sorption.
12. A "universal" partition function for inorganic phosphorus retention in
soils can be developed provided proper input parameters are measured.
These parameters include the measurement of "active" Fe and A1, time-,
dependence of phosphate adsorption-desorption, and phosphate sorption
isotherm parameters.
4
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SECTION 3
RECOMMENDATIONS
1. Measurement of octanol-water partition coefficients for a broad spectrum
of pesticides should be continued.. Special emphasis should be given to
recently developed highrpressure liquid chromatography (HPLCJ methods
for estimating octanol-water partition.coefficients. Also, this concept
should be extended for Ionic and ionizableorganic compounds.
2. Further evaluation of factors responsible for the measured nonslngular-
ity 1ji. pestid-.dft. adsorption-desorpt1 on Isotherms 1s essential.
3. The relative contributions of various particle-size fractions of soils
to pesticide retention should.be measured. Such data are now available
only for a limited number of organic compounds and not for a wide-range
of soil pesticide combinations. This Information will be used to
evaluate! the significance of runoff sediment "enrichment" by fines
in estimating total pesticide losses.
4. The disappearance rate of solvent-extractable parent compound should
not be used.as the only measure of pesticide degradation rate 1n soil-
water systems. The potential for significant accumulations of toxic
metabolites (specially under anaerobic conditions) and formation of
"Bound residues" must be taken into account.
5. Mineralization rate (i.e., total breakdown of pesticides to carbon
dioxide, water, and inorganic ions) should be used as 1ndex of pesticide
degradation rate because it represents total detoxification of the pesti-
cide. Because mineralization rates are generally smaller than parent
compound disappearance rates, the former provides a more, conservative
estimate of the pesticide degradation rate.
6. The rates and mechanisms of bound pesticide residue formation 1n soils
as well as the release characteristics and environmental toxicity of
these residues should be characterized. Special attention should also
be given to.rates pf formation and release of bound residues under an-
aerobic environments (encountered by sediment-bound pesticide residues
in streams, rivers, lakes, etc.)
7. Empirical regression equations are needed for describing the dependence
of pesticide degradation rates on soil environmental variables (temper-
ature and soil-water content or potential) in order to estimate degra-
dation rates for a given pesticide in various soils under several
environmental conditions.
5
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8. Simple experimental methods for measuring and/or estimating pesticide
degradation rates should be developed.
9. Standardized methodology (protocols) should be developed for measuring
phosphate sorption parameters, "active" soil components (Fe and A1
oxyhydroxides and solubilized Ca) involved in phosphate retention, and
the time-dependence of phosphate sorption-release in soil-water systems.
10. Further testing of various phosphate sorption models is required in
order to deyelop appropriate sorption parameters.
11. A quantitative index needs to be defined for the "crystal 1inity" of the
Fe and A1 oxyhydroxides in soils. Such an index will be used in devel-
oping a "universal" partition function for phosphate retention by soils,
in concept to pesticide partition coefficients based on soil organic
carbon.
6
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SECTION 4
RETENTION OF PESTICIDES IN SOILS
P.S.C. Rao and J.M. Davidson
METHODS FOR MEASURING PESTICIDE RETENTION
Over the past two decades a number of experimental methods were proposed
for measuring pesticide adsorpt.ion-desorption. in soi.lswater systems,..... The
basic objective of all these methods has been 'to measure the relationship at
equilibrium between the pesticide solution and adsorbed phase .concentrations.
Based upon the manner in which^ e^iilbrium.betweefl/.the.adsoT'Bert -and tffe
adsorbate 1s achieved, the adsorption methods can be grouped under "batch-
equilibrium" or "flowrequ1libr1umn methods. within each group, several
methods with minor variations, can be found. Because of their simplicity, trie
batch.methods are most widely used, while the flow methods have not received
equal attention.
In the batch methods, a known weight (iM) of air-dry soil Is suspended
in a pesticide solution of known volume (V,ml) and initial concentration
(Cf, yg/ml). This suspension is agitated for a pre-determ1ned time (from 1 hr
to 48 hrs) and the solution pesticide concentration (Ce, vg/ml) Is determined
after filtration or centrifigatlon (speeds ranging from 500 6 to 60,000 G)
to obtain a clear supernatent solution. Any change in solution concentration
(i.e., AC 3 Ci - Ce) is attributed to adsorption on the soil. Therefore, the
adsorbed phase concentration (Se, ug/g soil) at equilibrium is calculated as
follows:
Se = (V/m) (AC) [4-1]
Measurement of Se at several values of Ce then yields the adsorption isotherm.
An alternate, but less common,, procedure is the direct determination.of the
adsorbed-phase concentration by extraction of the soil with appropriate
organic solvents. In another variation of the batch method, the soil and
solution phases were separated during equilibration by a semi-permlable mem-
brane such as dialysis tubing or colloidon membrane (Bailey and White, 1964;
Hayes et al., 1968).
In the flow-equilibration methods, pesticide solution of known concentra-
tions. (C0» Rg/ml): is continually passed through.a. "flow cell" in which a known
weight of soil is either maintained 1n suspension (Grice and Hayes, 1972;
Grice et al., 1973) or is packed as a thin pad (Green and Corey., 1972; Burc-
hill. et al., 19731. A series of small volume fractions, of .the effluent solu-
tion are collected and the pesticide concentrations.in each.of these fractions
7
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is determined. A plot is then made of the effluent concentration (Cn) in sa'Ji
fraction versus cumulative effluent volume (Vn). By assuming that instanton-
ious equilibrium is achieved between the. solut.ion'and the adsorbed'phases dur-
ing displacement thrqugh the' flow, cell, the amount adsorbed can be calculated:
V
mS = C Vn - V C - / nC dV [4-2]
noncno i. j
where, Sn = adsorbed concentration (yg/g), Co = input concentration (yg/ml),
Vp = cumulative effluent volume (ml), Cn = effluent concentration (yg/ml)
at Vn, Vp = solution volume in the flow cell, and m = weight of soil in the
flow cell. Note that in Eq. [4-2], the three terms on the r.h.s. represent,
respectively, total amount of pesticide in input in solution within flow cell,
and total outflow. By performing the above calculation at selected values
of Vn or Cn, the flow cell method yields several S vs. C values from a single
displacement experiment. Unfortunately, the assumption of instantaneous
equilibrium is not necessarily satisfied for all soil-pesticide combinations.
In fact, a similar flow cell technique was used to measure the kinetics
of adsorption-desorption reactions in soils.
In the flow-through method proposed by Green and Corey (1971) a pesticide
solution of known concentration (C0) was displaced through a thin pad of soil
until inflow and outflow concentrations were equal. The total amount of (T)
pesticide adsorbed by the soil and that in the solution in the soil pad were
quantitatively extracted by a suitable organic solvent and measured. The
amount of pesticide adsorbed (S) by the soil was computed as:
s = i [T " VCJ [4-3]
m L o
where, V is the volume of solution (ml) retained by the soil pad. This
method is superior to other flow methods because (i) no assumptions regarding
adsorption kinetics are involved, and (ii) increases precision because the
amount adsorbed is directly quantified in contrast to batch methods. However,
like the batch method, the flow'method yields only one adsorption value, the
S value associated with C0. Thus, several soil pads exposed to a range of C0
values are required for determination of an adsorption isotherm.
The degree of success and acceptance of a given method depends primarily
upon (i) the specific pesticide-soil combination, (ii) the ease with which
large numbers of measurements may be performed, (iii) the intended applica-
tion of adsorption data, and (iv) the precision of measurement. Green et al.
(1976) present an excellent review of the above methods. They concluded that
although the flow-equilibration methods offered obvious advantages (increased
precision, maintaining the soil structure), batch methods will continue to be
extensively used because of their simplicity. The batch method, in fact, is
specified in the "Protocol for Adsorption Tests" published by the U.S. Envi-
ronmental Protection Agency (1975).
ADSORPTION ISOTHERM MODELS
Various mathematical relationships have been used to describe equilibrium
pesticide adsorption-desorption in soil-water systems. Among the more
8
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successful are the FreundUch and Langmuir equations. The FreundUch equation
is stated as:
S ° KCN [4-4]
where, S =» amount pesticide adsorbed (ug/g soil), C 3 solution-phase pesticide
concentration (ug/ml), and K and N are empirical coefficients ttiat depend on
the soil-pesticide system. Taking natural logarithms of both sides of
Eq.[4-43 yields,
In S = In K + N In C. [4-5]
Thus, the coefficients K and N may be obtained, respectively, as the intercept
and..slope of log-log plots of S versus C. The Langmuir equation may be
stated as
k C
J + k C
S = -^TTr [4-6]
where, Smaoc ^.njax^nww.-adsorption capacity (vg/g soi l )., k = Langmuir coeffi-
cient relatM to adsorption, bonding energy (ml/ug), and S and C are as definv
ed earlier; The more commonly used linear form of the langmuir equation is,.
Ia ft— + C4'7]
max max
It 1*S evident from Eq. [4-7] that from a plot of C/S versus l/C, the coeffi-
cients k and %£* can be calculated.
The Langmuir model was originally developed to describe adsorption of
gases on homogeneous surfaces. Three important assumptions made 1n deriving
Eq. [4-6] are (i) the energy of adsorption 1s the same for all sites and 1s
independent of degree of surface coverage, (11) adsorption occurs only on
localized "sites," With no.interaction betweerf adjoining adsorbed molecules,
and (111)''the adsorption maximum (Smax) represents a monolayer coverage.
Given these fairly restrictive assumptions, it Is not surprising that the
Langmuir equation generally fails to describe pesticide adsorption in such a
complex and heterogeneous media as soils. The ability of the. FreundUch equa-
tion to describe pesticide adsorption on soils, both at low and high concen-
trations, 1s well-documented (Hamaker and Thompson, 1972;, Davidson et al.,
1978; Rao and Davidson, 1979). Although 1t 1s generally suggested that the
FreundUch equation has no conceptual basis, Eq. [4-4] can be derived from
the Langmuir equation: if the energy of adsorption is assumed to decrease with
Increasing surface coverage (Thomas and Thomas, 1967).
For solution concentrations similar to those associated with agricultural
eco-systerns, Eqs. [4-4] and [4-6] may be assumed to be linear,
S = Kp C [4-8]
when N - 1 in Eq. [4-4] and when kC«l in Eq. [4-6]. The Kg vahje has units
of ml/g and Is commonly referred to is the adsorption partition, coefficient.
9
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10.0
Deviation From Linear Isotherm
1.0
1.0
0.1
10.0
0.1
SOLUTION CONIC., jjg/ml
FIGURE 4-1. Graphical representation of the error introduced by
the assumption of linearity when the adsorption
isotherms are nonlinear. The numbers on the lines
are the values of Freundlich constants N (see Eq. 4-4
and 4-8).
10
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The error introduced by assuming the adsorption Isotherm to be linear
depends upon the values of C and N. This error can be represented as the
ratio of Eq. [4-4] and Eq. [4-8] and is equal to C"-l". A plot of CN-1 versus
C in the range of 0.1 to 10 ug/ml and for N values ranging from 0.5 to 1.0
is shown in Figure 4-1. It may be noted that an error factor of 1.0 repre-
sents perfect agreement between linear and nonlinear isotherms. Thus, for"
C < 1.0, the amount adsorbed in under-predicted, while for C > 1.0, the
amount adsorbed is over-predicted by assuming linearity. However, for
0.1 < C < 10.0 and 0.5 < N < 1.0, as shown in Figure 4—1, the maximum devia-
tion will be by a factor of 3, 1f Eq. [4-8] was used instead of Eq. [4-4].
Such errors may be tolerable for many practical applications as in nonpoint
source pollution models. However, for large solution concentrations, such as
those encountered under pesticide waste disposal sites, the amount adsorbed
could easily be over-estimated by an order of magnitude or more (Davidson et
al., 1978; Rao and Davidson, 1979).
TrME DEPENDENCE OF ADS0RPTI0N-DES0RPTI0N
A majority of the literature deals with the partitioning of pesticides
at' equilibrium between the soil .and solution phases while a very few re-
searchers have investigated the rate at which equilibrium is achieved. Under*
conditions of steady or transient water flow in soils, sufficient time may
not be available to achieve instantaneous local equilibrium for pesticide
adsorption-desorption. Consequently, many investigators studying pesticide
movement have had to. measure the kinetics of the adsorption-desorptlon
processes..
The amount of pesticide adsorbed with time was assumed to follow revers-
ible non-linear kinetics to yield the following rate expression (Van fienuch-
ten et al., 1974):
where, ky and k2 are, respectively, the kinetic rate coefficients (hi—1) for
forward and backward reactions, 9 is soil-water content (cmVcm^), p is soil
bulk density (g/cm^), t is time (hr), and C and S are as defined previously.
Note that at equilibrium (i*e., 3S/3.t .= 0), Eg. [4-9] reduces to Eq. [4-4]
with the Freundlich coefficient K equal to (ekj/pk?). Lapidus and Amundson
(1952) and Oddson et al. (1.970) ..used,'Eq. [4-9] with *1=1, which describes
reversible first-order processes leading to a linear isotherm at equilibrium.
A detailed study of 2,4-D herbicide adsorption kinetics on three clay
minerals (illite, kaolinite, and montmorillonite) was reported by Haque et al.
(1968). The rate expression used by these, authors was:
where, $ = qt/9$» 9t 1s amount adsorbed (pg/g) at time t (hrs), qe is amount
adsorbed .at equilibrium (t ¦* ® ) , and k' is. the adsorption rate constant
(hr-1). Note that in Eq^ [4-10}, the rate of adsorption is proportional to
3S
at
[4-9]
[4-103-
1.1
-------
the distance from equilibrium. In deriving Eq. [4-10], it was assumed that
the reverse reaction, the desorption rate, was small enough to be neglected.
This assumption was satisfied by using large amounts of clay (reactive sur-
face available for adsorption) and low 2,4-D solution concentration. Further
refinements to Eq. [4-10] were made by accounting for the change in free
energy of activation with surface coverage. The calculated values for k'
ranged from 1.98 X 10-3 to 7.88 X 10-3 hr-1. The k' value was shown to de-
crease nonlinearly with increasing clay surface area and decreasing tempera-
ture.' Hague et al. (1968) concluded that the rate-limiting step in
adsorption was diffusion to the reactive sites within the clay matrix and not
the kinetics of reaction at the site.
Lindstrom et al. (1970) proposed a model for the kinetics of adsorption-
desorption processes. Their model was an extension of an earlier model
derived by Fava and Eyring (1956) who considered only adsorption. A second
improvement incorporated by Lindstrom et al. was that the "sticking probabil-
ity" (Langmuir, 1918) for the adsorbate on the adsorbent surface was allowed
to vary with degree of surface coverage. Their model also allowed for
adsorption and desorption energies- to change with surface coverage. This
model may be stated as
k 0
|| = [k2 exp (BS)] [(^.) C exp (-2SS) - S] [4-11]
where., B is similar to the surfa e stress coefficient described by Fava and
Eyring (1956), and other parameters are as defined for Eq. [4-9]. For
equilibrium conditions (3S/3t = 0), Eq. [4-11] reduces to:
S = [^4 [C exp (-2BS)]. [4-12]
The above equation may be rearranged as
0k,
In (S/S) = In -[-rM - 28S [4-13]
p *2
Therefore, the parameters 3 and (ek-|/pk2) may be evaluated from the slope and
intercept, respectively, of plots of In (S/C) versus S for various equilibrium
solution concentrations. The usefulness of Eqs. [4-12] and [4-13] for de-
scribing picloram movement in saturated soil columns was evaluated by van
Genuchten et al. (1974). They found that both kinetic models described mea-
sured data reasonably well at low pore-water velocities, but not at large
velocities.
The conceptual models described above are valid for homogeneous surfaces
because a single adsorption mechanism or a single type of adsorption site
is assumed to be responsible for adsorption. In soils, a variety of reactive
components exist and this assumption may not be valid. For instance each
reactive component of the soil (e.g., organic matter, clay minerals, etc.)
may provide different adsorption sites which vary in energies and kinetics
of adsorption-desorption. A further complicating factor is that not all
adsorption sites may be equally accessible. Leenheer and Ahlrich (1971)
reported that although 60% of the reaction was completed in only 1 minute,
12
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adsorption of carbaryl and parathion on organic matter continued at a slow
rate for another 2 to 3 hours. These authors suggested.that the rate-
limiting step for times .greater than 1 to 2 minutes was pesticide diffusion
to adsorption sites in the interior of the organic matter. Similar obser-
vations of Initial rapid reaction followed by a slow reaction over long
times have been reported by several authors (Hamaker et al,, 1966; Weber and
Gould, 1966; Wahid and Sethunathan, 1978).
NON-SINGULARITY Of ADSORPTION-OESORPTION
The implicit assumption made 1n most adsorption studies is that adsorp-
tion-desorptlon have the same characteristics and that Eqs. [4-4] - [4-8] can
be used to describe both adsorption and desorption isotherms. However, re-
cent research indicates that for several soil-pesticide systems, the
adsorption-desbrption, processes may .be non-singular and perhaps may even be
irreversible. Non-singularity Is said to exist..when, for a given equilibrium
solution -concentration , more .pesti.c1de is retained on the soil.during the
desorption phase than during the adsorption'phase. Some of the early data in
tfris. regard; was.presented. Swanson and Dutt (1973) and Horns by and Davidson
(1973). Similar resal ts fo^'a- .tergeniimber of .sail -pes tic.i4e * iystens; ha ve
been reported (yah Geiiuchten et al., 1974; Rap, .1974; Farmer and Aochi, 1974;
¦Murray et al1975; Peck, 1977). In sp1te of considerable .research*,,in this
area, the physical>chemicaT ^sis for the experimentally measured non-singu-
larity remains unclear at the present time/ Rtikhtar''(1976) conducted a
comprehensive study to examine the:relationship..betwfeen non-singularity and
the mechanismsy fcit»etics., and energies of ad$oipt.t©ij?desorptfon processes.
He found that the degree of non-singularity was directly proportional to the
amount adsorbed prior to initiation of desorption, the rate of adsorption,
and the adsorption energy. Mukhtar (1976) also presents an excellent review
of related work.
Based upon the observations reported, three major causes for the non-
singularity may be identified: (i) artifacts created, due to some aspect of
the method, (11) failure to establish complete equilibrium during adsorption
phase, and (iiij chemical and/or microbial transformations of the pesticide
during the course of the experiment! Each of these factors is discussed
below 1n detail.
Common to all studies dealing with non-singularity Is the batch equilib-
rium method. The adsorption isotherm points are measured as described in an
earlier section. Desorption Is initiated by centrifuging the "equilibrated"
soil-pesticide systems, removing a known volume of pesticide solution, replac-
ing with an equal volume of pest1c1de-free solution, and resuspending the
soil-pesticide solution. The procedure is repeated to develop desorption
isotherms initiated from a point on the adsorption isotherm. This procedure
then, involves repeated centrifligation and resuspension of the soil followed
by prolonged (up to 24 hours for each step) agitation. Such a treatment
could cause a breakdown of the soil particles, thus increasing the number of
adsorption sites during the desorption phase of the experiment (Savage and
Wauchope, 1974). A slow solvent action of .the aqueous solution could also
unmask new adsorption sites and increase thesites available pesticide adsorp-
tion (Harice* 1967). However, both these factors were found not to be
-------
significant in some experiments (Mukhtar, 1974; Rao and Davidson, 1980).
Diuron herbicide adsorption isotherms for soils subjected to a 30-minute sari-
cation pre-treatment were the same as those for unsonicated soils (Mukhtar,
1974). Sonication was expected to be a much harsher treatment and as a result
breakdown the soil structure more than agitation or tumbling which is coi'imcnly
employed. Identical pesticide adsorption isotherms were obtained for soils
samples with and without a pre-treatment which consisted of prolonged tumbl-
ing (up to 3 days) with centrifugation and resuspension once each day (Rao
and Davidson, 1980).
Rao et al. (1978) investigated the possibility that the centrifugal :)n-
resuspension step in the batch method might be inducing the observed non-
singularity. These authors measured adsorption-desorption isotherms for
several soil-pesticide systems using the batch method as described earlier
and two modifications of the batch method. Modifications were designed to
eliminate the centrifugation step and were: (i) a water-immiscible organic
solvent as a third phase to desorb the pesticide from the soil and aqueous
phases (3-phase method), and (ii) desorption by dilution of the soil-water-
pesticide system (Dilution method). For all soil-pesticide combinations
studied, nonsingular adsorption-desorption isotherms were obtained using the
"standard" batch method. The adsorption-desorption isotherms measured, using
the modified batch method, were nonsingular for certain soil-pesticide combi-
nations. Rao et al. (1978) concluded that the pesticide adsorption mechanism
played an important role in determining whether centrifugation induced non-
singularity. These authors recommended that the dilution method rather than
the "standard" batch method be routinely used for measuring adsorption-
desorption isotherms. The reasons as to why centrifugation induces non-
singularity are unknown at the present time and further experiments are need-
ed in this regard.
Failure to establish complete equilibrium between the soil and pesticide
prior to initiation of desorption has been cited as another cause of non-
singularity (Snoeyinketal, 1969). Diffusion-controlled migration of pesti-
cide to adsorption sites within the soil organic matter and/or clay matrix
would result in a psuedo-equilibrium (Hance, 1969; Adamson, 1967; Rao et al.
1979). Based on such conceptualization, Selim et al. (1976) proposed a two-
site model for adsorption-desorption. Using this model, they were able to
simulate non-singularity when desorption was initiated prior to when adsorp-
tion equilibrium was attained.
Chemical and microbiological transformations of the pesticide during the
course of the experiment have also been suggested to cause the apparent non-
singularity in pesticide adsorption-desorption isotherms. Hamaker and Thomp-
son (1972) postulated that a portion of the adsorbed pesticide is held
stronger than the remainder and that this fraction tends to increase with
time. They also suggest that wetting and drying the soil may enhance this
effect. Knight et al. (1970) observed that diquat and paraquat undergo
slight rearrangement with time and become more difficult to desorb from a
soil. Cheng et al. (1979) demonstrated that a significant portion of the
non-singularity observed in 2,4,5-Tisotherms could be explained by accounting
for microbial degradation of the parent compound. It is not a common prac-
tice to sterilize or to add antibiotics to minimize the microbial activitv iri
14
-------
soils during the adsorption experiments. However, microbial degradation will
not be a significant factor for the more persistent pesticides. Chemical
transformations, such ai surface-catalyzed iiydrolysls of s-rtrlazine herbi-
cides, may also have similar effects as microbial degradation. This aspect
has hot been thoroughly Investigated.
A critical evaluation of the existing literature, which includes many
conflicting reports, Indicates that while non-singularity of pesticide
adsorptton-desorption: isotherms may often be an artifact, it could be real
and significant for certain compounds. Furthermore, under field conditions
which involve long contact times between the soil and pesticide, several of
the factors discussed earlier operating simultaneously could become signifi-
cant and lead to an apparent non-singularity. Therefore, 1t is important to
assess quantitatively the.errors introduced by not accounting for non-
singularity.
As indicated earlier, for-non^singular .isotherms.,-the preaftdlich: coeffi-
cients in Eq. [4-4] are different for adsorption and desorption. Thus,
Sa * *aCN* {4-14]
V
Sd. » l^c • [4-15]
where, the subscripts a and d denote, respectively , the adsorptl on and
desorption:iSotherms. Van Genuchteri et al. (1974);.aBtkmg others.,.have shown,
that the degree of non-singularity is dependent on the maximum amount adsorb-
ed tSm) before initiation of desorption. This relationship was expressed as
VS <>16]
where, B = Nd/N^. Eq. [4-16] can be restated in terms of the maximum solu-
tion concentration (Qn) prior to desorption as
N -N.
K„ = K.a Cma [4-173
Substitution of Eq. [4-17] for Kj in Eq. [4*15] yields,
N -N, N.
si ' KaCr c C4">«
The ratio S
-------
are singular. Van Genuchten et al. and others have shown that the value of
was related to Na and Sm; however, an average value of 6 = 1/2-3 was found *r>
be satisfactory (1.e., Na = 2.3 Nj). Using this relationship in Eq. [4-19]
gives
Si , c 0.5652K, c-0.5652Na [?.201
5, m
a
A further simplification of Eq. [4-20] is possible, if it is assumed that
10 pg/ml is the' largest value of Cm under normal agricultural field condi-
tions. Thus,
^ = (10°-5652"a) (C-0-5652"a) [4-21]
The assumption that Cm = 10 ug/ml is useful for illustrating errors
introduced when non-singularity'is not taken into account. The relationship
between Sd/Sa and C, given by Eq. [4-21], is presented graphically in
Fig. 4-2 for Cm - 10 yg/ml and several Na values that cover the range of mea-
sured values for a broad spectrum of pesticides. Similar curves can be gen-
erated for any other value of Cm using Eq. [4-20]. As evident in Fig. 4-2,
the error (i.e., the ratio Sd/Sa) is greater at low solution concentrations
and decreases with' increasing non'l inearity (Na
-------
(^=10jug/ml
SOLUTION CON C., og/ml
FIGURE 4-2. Errors introduced by the assumption that adsorption-desorption isotherms are
singular when, they are non-singular (see Eq. 4-20, 4-21).
-------
that soil organic matter content was the single best predictor of the adsorp-
tion isotherm parameters. Based on such results, Lambert et al. ('1965) hava
assumed that soil organic matter was the only soil constituent responsible r;r
pesticide adsorption. They-proposed the use of an adsorption partition co-
efficient (Kom)»
where Som is the quantity of pesticide (yg) adsorbed per gram of soil
organic matter and C is the corresponding solution concentration (yg/ml)
Lambert et al. (1965) obtained nearly constant Kom values for monuron -
tion for several soils ranging in organic matter content from 1.5 to 4.8f0.
Organic matter content was calculated by multiplying the experimentally deter-
mined value of organic carbon content by a conversion factor. Because various
authors have used different conversion factors (ranging from 1.7 to 2.0),
Hamaker and Thompson (1972) recommended that soil organic carbon content be
used to normalize pesticide adsorption partition coefficients. This param-
eter, denoted as Kqc, is equal to:
_ yg adsorbed/qm organic carbon ra..?7i
oc yg/ml solution L - J
Note that from Eq. [4-23],
(Kn) (100)
Koc = %QC [4-24]
where %0C is the organic carbon content of the soil, and Kg is the adsorp-
tion partition coefficient.
In deriving Eq. [4-24], it was assumed the Kq is linearly proportional
to %0C. For high %0C combined with low clay content, the organic matter may
be "piled up" resulting in less available adsorptive surface per unit weight
of OC (Hamaker et al., 1966). Similarly, for low OC contents, the "efficien-
cy" of OC appears to increase (Lambert et al., 1965; Hilton and Yuen, 1963;
Walker and Crawford, 1968; Shin et al., 1970). The variability in Kqq values
for a given pesticide was suggested to be due to the differences in "efficien-
cy" of the soil organic carbon among soils (Lambert, 1968). He proposed the
use of an empirical constant (n) based on a standard soil to account for the
variability. For example, a value of fi = 0.5 for a given soil would imply
that the soil organic carbon would only be 50% as "efficient" as that in the
standard soil. No data are presently available to establish whether the £2
value is a constant for a given soil regardless of the pesticide. Further-
more, selection of a "standard" soil would be somewhat ambiguous. Consider-
ing the practical utility of a "universal" adsorption partition coefficient
for each pesticide which is essentially independent of the soil type, the
errors introduced by above discussed factors may be relatively minor.
An exhaustive literature search was performed to compile adsorption
isotherm parameters (K, Kg, N, Koc) for a number of pesticides and related
compounds. The list of compounds included in this search was prepared on the
basis of "benchmark" pesticides (Goring et al., 1973; George Washington Univ.,
18
-------
1976; Sanborn et aT., 1977) and cover a broad spectrin,of herbicides, insecti-
cides, and fungicides frequentlyjiied in agri^Tture: A,complete listing of
K, Kq, N,. and KqC values is included in the appendix of this report, while
only overall means and coefficients of variation (CV) are shown 1n Table 4-1.
It is evident from the data presented in Table 4rl that the CV values
for K (or Kg) ranged from 13.5% to 158.5%, while the CV for Kqc are much
lower. This supports the previous suggestions that Kgr may be a universal
adsorption partition coefficient for each pesticide, me values of N are not
as variable as the K values; the overall mean and CV for N are, respectively,
0.87 and 14.8%. Therefore, the assumption of linear isotherms required in
using KqC values is apparently not valid for many pesticides. The error in-
troduced by assuming linear isotherms (N = 1),. however, are within a factor
of two or three as demonstrated earlier (See, Fig. 4-1).
There seem to be three major reasons tor the rather large variability in
the Kqc values shown in Table,4-U First, the. relationship between Kg and
%0C may be nonlinear; However, multiple regression analysis using this data
base did not reyeal.any consistent or significant trends in tfrls regard.
Second, although the, varlability in, Kqc values from .a.gi ven .referfertce-were
generally low.|CV = 40-60%), the CV'for KqC values pooled from several refer-
ences was ^generally higher.... This trend suggests that experimental methods
employed by varlousauthorsmay not/ have been the same. For example, shaking
methods contact time allowed between pesticide and soil, temperature, and the
analytic method; used, to assay the pesticide will contribute to the variabil-
ity noted. 'The third, factor was whether the adsorption parameters K, or. Kn
were- derived from aft entire isotherm or at a single concentration. Recall
that K s Kq for linear Isotherms, while for nonlinear isotherms Kg 1s concen-
tration-dependent. Therefore, adsorption coefficients determined from single
point measurement can yield under-estlmates of the actual value of K. The
results presented 1n this section clearly point out the need for standardiza-
tion of experimental methods (or protocols) for measuring adsorption iso-
therm parameters.
Octariol-Water Partitioning
In spite of two decades of extensive research efforts, the adsorption
isotherm parameters are available only, for..few .of the .large .number of pesti-
cides and related organic compounds currently 1n use. Therefore,, several
attempts have been, made to develop methods for predicting the adsorption par-
tition coefficients from available physical-chemical parameters of the pesti-
cides and soils. The concept of Kqc discussed earlier, 1s one such method.
Two methods based on extra-thermodynamic linear free energy concepts are dis-
cussed 1n this section.
Several authors (Weber, 1966; Ward and.Holly, 1966) have shown a close
relationship between the chemical structure and pesticide adsorption on soils.
Based upon such observations, Lambert (1969) derived a linear relationship
between the "parachor" and the adsorption partition coefficient (Kqc)• Para-
chor is an additive and constitutive function of molecular structure and is
related to molar volume (Vmj and surface tension (r) as follows: P = Vmrl/4.
IS
-------
Table 4-1. Summary of Adsorption Partition Coefficient Values Compiled from Published
Literature for Several Pesticides and Related Organic Compounds.
Number
K or Kq
N
K
In K
of
AC
oc
Pesticide
Soils
Mean (%CV)
Mean (%CV)
Mean (5£CV)
Mean (%CV)
AMETRYNE
32
6.16(65.1)
388.4(57.1)
5.808(9.8)
AMI BEN
12
1.40(145.2)
189.6(149.7)
3.748(52.0)
ATRAZINE
56
3.20(89.8)
0.86(9.9)
163.0(49.1)
4.966(10.7)
BROMACIL
2
72.0(102.1)
CARBOFURAN
5
1-05(111.8)
0.96(6.5)
29.4(30.0)
3.336(9.9)
CHLOROBROMURON
5
37.22(121.2)
0.74(8.8)
995.6(55.1)
6.804(6.9)"
CHLORONEB
1
1652.9(-)
CHLOROXURON
5
234.0(71.1)
4343.3(28.8)
8.343(3.5)
CHLORPROPHAM
36
816.3(—
CHL0RTH1AMID
6
5.57(39.7)
96.3(27.5)
4.549(7.2)
CIODRIN
3
74.8(59.1)
DDT
2
243118.0(65.0)
DICAMBA
5
0.11(103.9)
1.18(13.7)
2.2(73.5)
0.611(94.3)
DICHLOBENIL
34
3.0(70.9)
224.4(77.4)
5.223(11.0)
DIMETHYL AMINE
5
14.0(77.3)
1.00(0.5)
434.9(19.8)
6.058(3.4)
DIPROPETRYNE
5
13.5(91.5)
0.86 3.9)
1180.8(74.9)
6.874(10.2)
DISULFOTON
20
32.3(91.7)
0.92(10.3)
1603.0(144.2)
7.027(9.8)
DIURON
84
8.9(150.8)
0.83(28.8)
382.6(72.4)
5.680(14.8)
FENURON
10
2.11(120.8)
0.87(13.2)
42.2(84.7)
3.536(17.2)
LINDANE
3
20.1(13.5)
1080.9(13.0)
6.980(1.9)
(Continued)
-------
Table 4-1 (Continued)
Pesticide
Number
of
Soils
K or Kd
Mean (ICV)
N
Mean (XCVJ
oc
Mean (%CV)
In K
oc
Mean (SKCV)
LINURON
MALATHION
METHYL PARATHION
METHYL UREA
METOBROMURON
HONOLINURON
MONURON
NEBURON
p-CIILOROANILINE
PARATHION
PHENYL UREA
PICLORAM
PROMETONE
PROMETRYNE
PROPAZINE
SIMAZINE
TELONE (els)*
TELONE (trans)*
TERBACIL
THIMET
TR1THI0N
2,4-D
2.4-D AMINE
2.4,5-T
33
20
7
5
4
10
18
5
5
4
5
26
29
38
36
147
6
6
4
4
4
9
3
4
21.2
34.1
12.7
100.2)
167.1)
67.2]
3.5(80.1
6.7(62.8)
12.3(83.6
7,6 122.5)
166.8(68.3)
16.8(79.4
21.9(63.7)
4.9(91.9)
0.63(150.2)
7.2(147.5'
10.8(123.8
3.1(135.8
2.3(158.5
54.8(78.6
93.2(72.0
0.78(145.0)
8.8(77.7
74.6(26.6)
0.78(128.6)
2.0(112.5)
1.6(87.3)
0.71(6.6)
0.94(12.9)
0.76(15.7
0.76(10.1
0.83(20.6
0.70(2.6
1.03(2.9
0.85(13.2)
0.81 (4*4.}
0.82(5.3)
0.95(3.6)
0.78(5.2)
0.93(6.1
0.97(4.2
0.94(7.4
1.01(4.0
0.75(9.0
862.8
1796.9
5101.5
58.8
271.5
284.3
183.5
3110.5
$61.5
10650.3
76.3
25.5
524.3
614.3
153.5
138.4
798.1
1379.0
41.2
3255.2
46579;7
19.6
109.1
Stf.l
(72.3)
(65.9)
113.6)
15.1;
37.1
55.2
60.8
23.5
33.6
74.6
12.3
138.
143.
99. i:
37.0,
12.6
44.3
45.4
42.2
49.5
80.2
72.4
30.2
45.3
• w f
).5)
1.6)
6.55(10.1)
7.303(8.6)
7.673(20.9)
4.1166(3.7)
5.553(6.6
5.514(9.9
5.069(10.7)
8.018(3.2)
6.286(5.3)
9.042(8.9)
4.324(3.8)
2.692(36.4)
5.721(17.4
6.100(12.9
4.949(9.2)
4.625(15.5)
6.598(6.8)
7.140(6.6)
3.646(12.3)
7.984(6.7)
10.419(10.0)
2.823(19.1)
4.657(7.2)
4.296(11.6)
*Vapor-soild adsorption
-------
Comparison of parachor values for various compounds is therefore equivalent tc
comparison of their molar volumes modified to account for the differences in
surface tension. Using the data of.Hancefor seven phenyl urea herbicides,
Lambert (1967) confirmed the -linear relationship between P and KoC. Hovvever,
Briggs (1969) found poor correlations between P and Kqc- It was pointed out
by Hance (lg^) that the concept of parachor should be used only with un-
ionized molecules that do not form hydrogen bonds. Because of difficulties
in calculating the'parachor values .for pesticides, this concept has not been
thoroughly tested: However, important theoretical advances in molecular
structure-activity relationship are now being made (Hopfinger and Klopman,
1978; Hopfinger and Battershell, 1976; Forsythe and Hopfinger, 1978).
Lambert and coworkers (1965, 1966, 1967, 1968) have suggested that the
role of soil organic matter in adsorption of neutral organic molecules was
similar to that of an organic solvent in liquid-liquid extraction. They fur-
ther state that KoC values should be related to pesticide partitioning be-
tween water and an immiscible organic solvent. Although various organic
Solvents could potentially be used, a considerably large data base and sound
theoretical basis currently exists for 1-octanol water partition coefficients
(Leo et al., 1971). More recently several authors have reported Kqc values
for a range of pesticides and industrial organic wastes (Metcalf and Lu, 1978;
Karickhoff and Brown, 1978; Briggs, 1973; Chiou'et al., 1977; Kenaga, 1975;
Karickhoff et al., 1979). A linear relationship between log KqW and log Kg-
values for 30 pesticides was reported by.Briggs. Similarly, Karickhoff (19/9)
obtained the following relationships for s-triazines and dinitro-aniline
herbicides
log Kqc = 0.94 log KQW + 0.02 [4-25]
and for polycyclic aromatic hydrocarbons (Karickhoff and Brown, 1978),
log K = 1.0 log K +0.21 [4- 5]
•OC ow
Koy( values for several pesticides reported in the literature are summarized in
Table 4-2. These Kow values.were paired with available Kqc values (see
Table 4-1) and were used to obtain the following regression equation (r? =
0.91)
log Kqc = 1.029 log KQW+0.18 [4-27]
A graphical representation of Eqs. [4-25] and [4-27], along with the data for
13 pesticides, is presented in Fig. 4-3. An excellent agreement between
Eqs. [4-25], [4-26], and [4-27] is apparent. This is especially important
considering the fact that the data used to develop Eq. [4-27] was obtained
from several references.
It is apparent from the above discussion that octanol-water partition
coefficients may be good predictors of adsorption partition coefficients for
pesticides. Furthermore, KqW values have also been successfully used as pre-
dictors of bioaccumulation potentials and bioactivity indicators for a wide
range of environmental contaminants (Metcalf and Lu, 1978; Chiou et al., 1977)
22
-------
Table 4-2. Stannary of Octanol-Water partition Coefficients (K )
for Pesticides Compiled from Literature,
Pesticide
Analytic
Method
ow
Log K
ow
A. INSECTICIDES
ALOICARB1
ALTOSID1,
CARBARYL1
CARBOFURAN1
CHLORDANE1 ,
CHLORPYRIFOSi
CHLORPYRIFOS,
CHLORPYRIFOS
CHLORPYRIFOS*. METHYL*
CHLORPYRIFOS, METHYL3
DDD*
DDE*-
DDE ,p>p2
DBT2
DOT p.p?
DDVPl
DIALIF0R3
DIAZINONl
DICHL0FENTHI0N3
DICIFOLl
DIELDRINl
DINOSEBl
ENDRINl
ETHOXYCHLORl
FENITROTHION3
HCB2
HEPTACHLOR1
LEPTOFOSl
LEPTOPHQS3
LINDANE1
MALATHION1
MALATHION3
METHOMYL1
METHOXYCHLOR1
METHOXYCHLOR4 ,
METHYL PARATHJON1
PARATHION3
PERMETHRINl
?
5.OOOOOE+OO
6.98970E-01
3H
1.76000E+02
2.24551E+00
14C
6.51000E+02
2.81358E+00
14C
2.07000E+02
2„31597E+00
?
2.10800E+Q3
3.32387E+00
GC
2.05900E+03
3.31366E+00
?
6.60000E+04
4.81954E+00
GC
T.28825E+05
5.11OOOE+OO
?
1«97000E+03
3.29447E+00
GC -
2.04170E+04
4.30999E+00
?
1-15000E+05
5.06070E+00
?
7..3445QE+04
4.:86596E+00
7
4.89779E+05
5.69000E+00
?
3.70000E+05
5.56820E+00
?
K54882E+06
6.19000E+00
GC
1.95000E+02
2.29003E+00
GC
4.89780E+04
4.69000E+00
GC
1.05200E+03
3.02202E+00
GC
1.38038E+05
5.14000E+00
?
3.46100E+03
3.53920E+00
14C
4.93000E+03
3.69285E+00
GC
1:..980OOE+G2
2..29667E+00
?
1..6190QE+03
3.20925E+00
?
.1. T8000E+03
3.07188E+00
GC.
2.29900E+03
3.36154E+00
?
1.66000E+06
6.22011E+00
?
7.36600E+03
3,86723E+00
14C
4.12200E+03
3.61511E+00
GC
2.04174E+06
£.31000E+00
GC
6.43000E+02
2.80821E+00
14C
2.30000E+02
2.36173E+00
GC
7.76000E+02
2.88986E+00
UV
1.20000E+01
1.07918E+00
3H
2.05000E+03
3.31175E+00
GC
1.20000E+05
5..07918E+00
14C
2.07600E+03
3.31723E+00
GC
6.45500E+03
3.80990E+00
GC
7.53000E+02
2.87679E+00
(Continued)
23
-------
Table 4-2. (Continued)
AnaTyti c
Pesticide. Method KQw Log Kqw
PHORATE1
?
8.23000E+02
2.91540E+00
PHOSALOME^
PHOSMET ,
PROPOXUR
RONNEL3
GC
1.99530E+04
4.30001E+00
GC
6.76000E+02
2.82995E+00
7
2.80000E+01
1.44716E+00
GC
7.58580E+04
4.88000E+00
TERBUFOS1
?
1.67000E+02
2.22272E+00
TOXAPHENE1
?
1.69500E+03
3.22917E+00
B. HERBICIDES
ALACHLOR1
GC
4.34000E+02
2.63749E+00
ATRAZINE
14C
2.12000E+02
2.32634E+00
ATRAZINE1
BIFENOX1,
BROMACIL1 ,
CHLORAMBEN1
T4C
2.26000E+02
2.35411E+00
14C
1.74000E+02
2.24055E+00
7
1.04000E+02
2.01703E+00
U V
1.30000E+01
1.11394E+00
CHLOROPROPHAM'l
.GC
1.16000E+03
3.06446E+00
DALAP0N2
?
5.70000E+00
7.55875E-01
DALAPON. NA SALT2
DICAMBAl
7
l.OOOOOE+OO
O.OOOOOE+OO
14C
3.00000E+00
4.77121E-01
DICHLOBENIL*
UV
7.87000E+02
2.89597E+00
DIURONl
UV
6.50000E+02
2.81291E+00
MONURONl
UV
1.33000E+02
2.12385E+00
MSMAl
AA
8.00000E-04
3.09691E+00
NITROFENl
?
1.24500E+03
3.09517E+00
PARAQUAT .2HCL1
14C
l.OOOOOE+OO
O.OOOOOE+OO
PICLORAM2
?
2.0O000E+00
3.01030E-01
PROPACHUORl
7.
4,lOOOOE+Ol
1,61278E+00
PROPANILl
?
1.06000E+02
2.02531E+00
SIMAZINEl
14C
8.80000E+01
1.94448E+00
TERBACIL"
14C
7.80000E+01
K89209E+00
TRIFLURALINl
14C
1.15000E+03
3.06070E+00
2,4-D
14C
4.16000E+02
2.61909E+00
2,4-Dl
14C
4.43000E+02
2.64640E+00
2,4-05
7
6.46000E+02
2.81023E+00
2,4,5-T2
1
7.00000E+00
8.45098E-01
2,4,5-T, BUTYL ESTER2
?
6.40000E+04
4.80618E+00
2,4,5-T OCTYL ESTER2
14C
9.09000E+02
2.95856E+00
(Continued)
24
-------
Table 4-2. (Continued)
Analytic
Pesticide Method KQW Log KQW
C. FUNGICIDES
BENOMfL1 GC 2.64000E+02 2.42160E+00
CAPTAN* UV 3.30000E+01 1.51851E+00
PGP1 14C 1.42900E+04 4.15503E+00
References
1. Metcalf, R.L.,and P.Y.LU. 1978; Partition coefficients as
measures, of btoacctimutetliOn potential for organic •compoumte.
EPA report (in press).
2. Kenaga, E.E. 1975. Partitioning and uptaike of pesticides by
b1 ologitat systems, In. EwironmefrtaT Gtynanrtcs of Pesticides
(eds: R. Haque and O". Freed), Plenum Press, N.Y. p. 217-275.
3. Ghlouv C.T., V.H. Freed, D.W. Schraeddlng, and R.L. Kohnert. 1977.
Partition coefficients and bioaccumulatlon of selected organic
chemicals. Environ. Sc1. Techhol. 11:475-478.
4. Kafickhoff, S.H., and D»S. Brown. 1978. Paraquat, sorption as a.
function of particle size In natural sediments. J. Environ! Qual.
7:246-252.
5. Leo, A., C. Hanchi and D: Elklns. 1971. Partition coefficients
and their uses. Chem. Rev: 71:525-616.
25
-------
O)
o
1. Atrazine
2. Bromacil
3- Carb'ofuran
4- 2,4-D
5. Dicamba
6. Dichlobenil
7. Diuron
8. Lindane
9- Malathion
10-Methyl Parathion
11. Simazine
12.Terbacil
13. DDT
Figure 4-3. Relationship between KqC and KqW values for pesticides
reported in the literature. Tne solid line is a plot of
Eq. 4-27. The dashed lines are plots of Eqs. 4-25 and
4-26 and represent best-fit lines for data reported for
s-triazines, dinitroanalines, and polycyclic aromatic
hydrocarbons.
26
-------
Measurement of Kow values should yield a valuable data base for
future use.
Effects of Soil-Particle Size
The adsorption partition coefficients reported thus far in this manu-
script are for whole soils. The distribution of the. adsorbed pesticide be-
tween the various size fractions of the soil was not given any consideration.
Because of the larger specific surface area and higher organic carbon content,
the finer fractions are expected to adsorb larger quantities of pesticides
than the coarser fractions such as sand. A limited amount of work in this
area has been reported by Karickhoff and Brown (1978) and Karickhoff et al.,
(1979). These authors studied the adsorption of two pesticides and several
polycyclic aromatic hydrocarbons on several sediments and reported that the
total amount, of pesticide, adsorbed by the whole soil (denoted S,. u/g..soil)
can be written as,
S = :?¦ f1 S1 [4-28]
1-1
where, S1 i£ the amount adsorbed {u9/g size*fract10ff) and f* 1s the fraction
of the total, soil mass represented by ith size-fraction. Assuming a linear
adsorption isotherm, . Eq. [4r28] can be restated as:
S.*." f1 S1 = z fy id C > iCv C [4-29]
i.-l 1-1 v" 0
where, Kn and kJ are the average partition coefficients for the whole soil
and the ittl size fraction. It is apparent from Eq. [4-29] that,
Kd =kJ f1. [4-30]
It follows from Eqs. [4-28] and [4-30] that,
S1 = Kp (S/Kjj) [4-31]
Therefore, the amount of pesticide adsorbed on any particle-size fraction ca'n
be estimated given the mass fraction and partition coefficient for each size
fraction and the adsorbed concentration for the whole soil (sediment).
Karickhoff and Brown (1978) and Karickhoff et al. (1979) have measured
the adsorption of two pesticides and several polycyclic aromatics as a func-
tion particle-size on several natural sediments. They reported that adsorbed
concentrations varied over orders of magnitude among individual size frac-
tions with a pronounced preference towards the fine silt and clay fractions.
Differences In amount adsorbed were directly related to the organic carbon
content variations associated with each particle-size fraction. Based on
these findings, Eq. [4-30] can be restated as follows
" • *1 f 1 C4-32]
i=l oc
27
-------
where, kL. are the adsorption partition.coefficients "normalized" with re-
spect to the organic carbon content, OCV of the i™ size.
The Kow values for sand-sfze fraction were less than half of those for
finer size fractions (silt and clay); the sand fraction thus dilutes the
effects of the fines. A portion of their data for adsorption of pyrene and
methoxychlor on one sediment are shown in Table 4-3. Based on similar data
for other natural sediments, Karickhoff et al. (1979) recommended measurement
of Kjc values for sediment fines (-< 50 size) only. They also found excel-
lent agreement between Koc values and K0y values (See Eq. 4-25). Thus, the
problem of predicting the distribution of the amount adsorbed onto various
s;ize-fractions reduces to that of determining the following parameters:
(i) mass fraction and organic carbon content of the fines, and (ii) determin-
ing the-"Kow 'vilue for the compound of interest. Further testing of this
approach is urgently needed, especially for a variety of soil-pesticide com-
binations,
PESTICIDE LOSSES IN RUNOFF
For each runoff event, a certain amount of the applied pesticide is lost
both in the runoff water as well;as with- the sediment in the runoff. The re-
lative amounts 'of pesticide lost in each of these two phases may be estimated
as follows (Mulkey and Falco, 1977):
Where, ps is the sediment concentration in the runoff (g/ml), Kg is the
average adsorption partition coefficient (ml/g), Fw is the fraction pesticide
'lost "irr the water phase, and Fs is the fraction of pesticide loss associated
with ttie sediment phase. In deriving Eqs. [4-35] and [4-36] it was assumed
that the adsorption-desorption isotherms were linear and singular and that
sorption equilibrium is achieved instantaneously. Limitations of these
assumptions were discussed in earlier sections.
Using Eq. [4-35] the values of Fw were calculated for a broad range of
Ps and Kq values. These are listed in Table 4-4. It is evident that most of
the pesticide (> 9030 is lost in the water phase of the runoff, except for
highly adsorbed pesticides (Kq > 100) or for high sediment loads (ps > 1000).
Data from recent field studies (Smith et al., 1978; Leonard et al., 1979)
confirm these conclusions. It should be recognized that the pesticide concen-
trations in the sediment-phase are generally much larger than those in the
water-phase. However, because of much larger volume of water in the runoff
compared to the sediment mass, the total pesticide loss in the water-phase is
greater.
Wauchope (1978) presents an excellent review of the literature on pesti-
cide losses measured in runoff from agricultural watersheds. The data he
F„ ¦ [1 - psKd]-'
[4-35]
[4-36]
28
-------
Table 4-3. Adsorption. Partition Coefficients (Kq and K^)
for Various Particle-Size Fractions of Hickory
Hill Sediment.
(Adapted from Karickhoff and Brown, 1978)
Part1ele-S1ze
Pyrene
Methoxychlor
Fraction
% OC
A-
icL X 10"5
oc
A
K* X 10"5
oc
SAND
0.13
4?
0.32
53
0.41
COARSE SILT
3.27
3000
0.92
2600
0.80
MEDIUM SILT
1.98
2S00
1.30
1800
0.91
FINE SILT
1.34
1500
1 - TO
1400
1.00
CLAY
1.20
1400
1.20
1-100.
0.92
Table 4-4. Influence of Kg and ps on the Pesticide Lost 1n
the Water-Phase of the Runoff. Values Shown,
are % of the Total Loss.
Adsorption
Partition
Coeff,,
Rq (ml/g)
Sediment Concentration, p3 (m
9/1)
TO2
103
M4'
105
TO5
10"1
99.99
99ii99
99.90
99.01
90.01
O
O
99.99
99.90
99.01
90.91
50. Off
101
99.90
99.01
90.91
50.00
9.09
102
99.01
90.91
50.00
9.09
0.99
TO3
90.91
50.00
9.09
0.99
0.11
29
-------
compiled demonstrated that total pesticide losses in the runoff were in gen-
eral less than 0.5% of the amount applied; paraquat herbicide and organo-
chlorine insecticides that are highly sorbed to the soil were the exceptions.
Single event losses as high as 10% were recorded when the runoff event occur-
red on the site shortly after pesticide application. However, the probabil-
ity of such events, termed "catastrophic" events, appears to be low under
most field conditions. The total pesticide loss in each runoff event general-
ly decreased exponentially with time and was strongly correlated with the
total amount of pesticide remaining in the runoff active zone (0-1 cm depth)
of the soil surface (Leonard et al., 1979; Smith et al., 1978). Therefore,
the pesticide losses in runoff are dependent upon the "available" amount of
pesticide in the surface soil, which in turn is determined by the persistance,
retention, and mobility of the pesticides.
SUMMARY
A considerably large data base exists for estimating the partition co-
efficients for pesticide retention on soils. Errors associated various
simplifying assumptions (e.g., linear and singular isotherms; instantaneous
equilibrium) appear to be within a factor of 2 or 3 and may be tolerable for
most NPS pollution applications. For a given pesticide, adsorption partition
coefficients based on soil organic carbon were fairly constant regardless of
soil type. Furthermore, pctanol' water partition coefficients are good pre-
dictors of adsorption partition coefficients. More research in this area
would be helpful.
Seasonal pesticide losses by runoff from agricultural fields, in general,
are less than 0.5% of the amount applied. Although pesticide concentrations
in the sediment phase are larger that those in the water phase, pesticide
carried in the water phase accounts for > 90% of the total loss for a given
runoff event. Highly sorbed pesticides (e.g., paraquat and diquat, chlorinat-
ed hydrocarbon insecticides) are the exceptions to this rule.
REFERENCES FOR SECTION 4
Adams, R. T., and F. M. Kurisu. 1976. Simulation of pesticide movement on
small agricultural watersheds. Environ. Systems Lab., Calif. Report
prepared for USEPA, Athens, Ga. EPA 600/3-76-066. 324 pp.
Adamson, A. W. 1967. Physical chemistry of surfaces. Interscience, N.Y.
Bailey, 6. W., and J. L. White. 1964. Pesticide-Soil Colloid Interactions.
Unpublished Progress Report, Grant EF-00055, Purdue Univ. 63 pp.
Bowman, M. C., M. S. Schecter, and R. L. Carter. 1965. Behavior of
chlorinated insecticides in a broad spectrum of soil types. J. Agri.
Food Chem. 13:360.
Briggs, G. G. 1969. Molecular structure of herbicides and their sorption
by soils. Nature 223:1288.
30
-------
Briggs, G. G. 1973. A simple relationship between soil sorption of
organic chemicals and their octanol/water partition coefficients.
Proc. 7th British Insecticides and Fungicides Conf. 11:475-478.
Briggs, G. G., and J. E. Dawson. 1970. Hydrolysis of 2,6-dichlorobenzo-
nltrile in soils. J. Agr1. Food Chem. 18:97-99.
Bruce, R.. R., L. A. Harper, R. A. Leonard, W. M. Snyder, and A. W. Thomas.
1975. A model for runoff of pesticides from small upland watersheds.
Joum. Environ. Qual. 4:541 -548.
Burchill, S., M. H. Cardew, M. H. B. Hayes, and R. J. Smedley. 1973.
Continuous flow methods for studying adsorption of herbicides by soil
dispersions and soil columns. Proc. European Weed Res. Coun. Symp.,
Herbicides-Soil pp. 70-79.
Bomside, 0. C., and T. L. Lavy. 1966. Dissipation.of Dicamba*. Weeds
14:211-214.
Chenif, H. H. 7977. Persona-l conrnutricat 1 ooUnpublished data.
Cheung, M..W. 1973. Equilibrium a«l. kinetic processes of the interactions
of 4-amino-3,5»6-tr1chlorop1coliftic acid (plcloram) and 0,0-diethyl-0-
p-n1trophenyl. phosphorothioate (parathion) with soils. Unpublished
Ph.D. Thesis., Univ. of Calif., Davis.
Chiou, C..T., V. H. Freed; D. U'. Schmfiddlng, and R. I. Kohnert. 1977.
Partition coefficients and bioaccumulation of sellected organic
chemicals. Environ. Sci. Techno!. 11:475-478.
Colbert, F. 0., V. V. Volk, and A. P. Appleby. 1975. Sorption of atrazine,
terbutryn, and GS-14254 on natural and 1ime-ammended soils. Weed Sci.
23:390-394.
Crawford, N.. H., and A. S. Donigian, Jr. 1973. Pesticide transport and
runoff model for agricultural lands. EPA-660/2-74-013. 212 pp.
Dao, T. H., and T. L. Lavy. 1978. Atrazine adsorption on soils as
influenced by temperature, moisture content, and electrolyte concen-
tration. Weed Sci. 26:303-308.
Davidson, J. M., L. T. Ou, and P. S. C. Rao. 1978. Adsorption, movement,
and biological degradation of high concentrations of selected pesti-
cides in soils. Proc. 4th Annual Res. Symp. "Land Disposal of
Hazardous Wastes." EPA-600/9-78-016. pp. 233-244.
Day, B. E., L. S. Jordan, and V. L. Jolliffe. 1968. The influence of
soil characteristics on the adsorption and phyto-toxicity of simaxine.
Weed Sci. 16:209-213.
Donigian, Jr., A. S., and N. H. Crawford. 1976; Modeling pesticides and
nutrients on agricultural lands. EPA-6Q0/2-76-043 . 318 :pp.
31
-------
Environmental Protection Agency. 1975. Guidelines for Registering Pesti-
cides in United States. Federal Register. 40(123):26802-26928.
Farmer, W. J., and Y. Aochi. 1974. Picloram sorption by soils. Soil Sci.
Soe. Amer. Proc. 38:418-423.-
Fava, A., and H. Eyring. 1956. Equilibrim and kinetics of detergent
adsorption - A generalized equilibrim theory. J. Phys. Chem. 60:890.
Forsythe, K. H., and A. J. Hopfirrger. 1978. A quantitative model of
biomolecular solvation. (Manuscript in review).
Frere, M. H. 1978. Models for predicting water pollution from agricul-
tural watersheds. Ln Cortf. on Modeling and Simulation of Land, Air,
and Water Resource Systems. Int. Fed. Inf. Processes, Ghent, Belgium,
pp. 501-509.
Frere, M. H., C. A. Onstad, and H. N. Holtan. 1975. ACTM0, an agricul-
tural chemical transport model. AR5-H-3, USDA, Washington, D.C. 54 p.
Furmidge, C. G,. L., and J. M. Osgerby. 1967. Persistance of herbicides in
soil. J. Sci. Food Agric.. ' 18:269-273.
Gaynor, J. D., and V. V. Volk. 1976. Surfactant effects on picloram
adsorption by sotl-&. Meed Sci. 24.:,54.9-553,.¦
Geissbuhler, H., C. Haselback, and H. Aebi. 1963. The fate of N'-
(4-chlorophenoxy)-phenyl-N,N-dimethylurea (C-1983) in soils and plants.
Weed Res. 3:140-153.
George Washington Univ. 1976. A literature survey of benchmark pesticides.
The George Washington Uni-v, Medical Center., March 1976. 252 pp.
Goring, C. A. I., J. W. Hamaker, and D. A. Laskowski. 1973. A proposed
approach toPR-70-15 guidelines for studies to determine the impact
of•pesticides in the environment. Unpublished paper,-.presented at
¦the .Pesticide Division meetings of the Am. Chem. Soc., Dallas, Texas.
Graham-Bryce, I. J. 1967. Adsorption of disulfoton by so.i l. ;J. Sci.
Food Agric. 18:72-77.
Green, R. E., and J. C. Corey. 1971. Pesticide adsorption measurement by
flow equilibration and subsequent displacement. Soil Sci. Soc. Amer.
Proc. 35:561-565.
Green, R. E., and S. R. Obien. 1969. Herbicide equilibrium in relation to
soil water content. Weed Sci. 17:514-519.
Green, R. E., J. M. Davidson, and J. W. Biggar. 1976. An assessment of
methods for determining adsorption-desorption of organic chemicals.
Proc. Intern. Congress on Agrochemicals in Soils, ISSS, Israel.
(In press).
32
-------
Grice, R. E., and M. H. B. Hayes. 1972. A continuous flow method for
studying adsorption and desorption of pesticides In soils and soil
colloldel systems. Proc. 11th..British Weed Control Conf. 2:784-791.
Grlce, R. E., M. H. B. Hayes, P. R. Lundte, and M. H. Cardew. 1973.
Continuous flow method for studying adsorption of organic chemicals
by a humic add preparation. Chem. & Ind. (London) pp. 233-234.
Grover, R. 1971. Adsorption of picloram by soil colloids and various
other adsorbents. Weed Sci. 19:417-418.
Grover, R. 1974. Adsorption and desorption of trlfluralin, triallete,
and diallete by various adsorbents. Weed Sci, 22:405-408.
Grover, R. 1975. Adsorption and desorption.of urea herbicides in soils.
Can. J. Soil Sci. 55:127-135.
Grover, R. .1977. Mobility of dicamba., picloram* and; 2,4-D in soil
columns. Weed Sc1. 25:159-162.
Grover, R., and R. J. Hance. 1969. Adsorption of some herbicides by
soil and roots. Can. J. Plant Sci. 49:i78-380.
Grover, R., and A. E. Smith. 1974. Adsorption studies with the acid and
dlmethylaml-ite forms of 2*4-D and dicaraba* Can., J. Soil Sci. 54:179-
186.
Hamaker, J. W., and J. M. Thompson. 1972. Adsorption. In (eds. C.A.I.
Goring and J.W. Hamaker) Organic Chemicals 1n the Environment, Mercel
Dekker Inc., N.Y. pp 51-139.
Hamaker, J. W., C. A. I. Goring, and C. R. Youngson. 1966. Sorption and
leaching of 4-aminp-3,5,&-trich:loropico:l1n1c acid in soils. Organic
Pesticides in the Environment,. Adv. In Chera. 60:23-37.
Hance, R. J. 1965. The adsorption' of urea afftf some of Its derivatives by
a variety of soils. Wefcd Res. 5:98-107.
Hance, R. J. 1967. The speed of attainments of sorption equilibria in
some systems ihvolv1ng herblcides. Weed Res. 7:29-36;
Hance, R. J. 1969. An empirical relationship between chemical structure
and the sorption of some herbicides by soils. Jour. Agric. Food Chem.
17:667-668.
Hance, R. J. 1976. Adsorption of glyphosate by soils. Pest. Sci. 7:363-
366.
Haque, R., F. T. Lindstrom, V. H. Freed, and R. Sexton. 1968. Kinetic
study of the sorption of 2,4-0 on some.clays. Environ. Sci. Tech.
2:207-211.
33
-------
Harris, C. I. 1966. Adsorption, movement, and phytotoxicity of monuron
and s-triazine herbicides in soils. Weeds 14:6-10.
Harris, C. I., and T. J. Sheets. 1965. Influence of soil properties on
adsorption and phytotoxicity of CIPC, diuron, and simazine. Weeds
13:215-219.
Hayes, M. H. B., M. Stacey, and J. M. Thompson. 1968. Adsorption of
s-triazines by soil organic matter preparations. hi Isotopes and
Radiation in Soil Organic Matter Studies, IAEC, Vienna, pp. 75-90..
Helling, C. S. 1971. Pesticide mobility in soils: III. Influence of
soil properties. Soil Sci. Soc. Amer. Proc. 41:743.
Hilton, H. W., and Q. H. Yuen. 1963. Adsorption of several pre-emergence
herbicides by Hawaiian sugarcane soils. J. Agric. Food Chem. 11:230-
234.
Hopfinger,-A. J., and R. D.'Battershell. 1976. Application of SCAP to drug
design. 1. Prediction of octanol-water partition coefficients using
solvent-dependent conformational analyses. Jour. Medicinal Che.
19:569-573.
Hopfinger, A. J.,.and 6. Klopman. 1978. A QSAR study of nitrosamine
carcinogenicity using aqueous, 1-octanol solution free energies and
the associated partition coefficients as correlation features.
Chemical-Biological Interactions, Vol. 20.
Hornsby, A. G., and J. M. Davidson, 1973. Solution and adsorbed fluo-
methuron concentration distribution in a water-saturated soil:
Experimental and predicted evaluation. Soil Sci. Soc. Amer. Proc.
37:823-828.
Jamet, P., and M. A. Piedallu. 1975. Mouvement du carbofuran dans differ-
ent types de sols. Phytiatrie-Phytopharmacie 24:279-296.
Karickhoff, S. W., and D. S. Brown. 1978. Paraquat sorption as a function
of particle size in natural sediments. J. Environ. Qual. 7:246-252.
Karickhoff, S. W., D. S. Brown, and T. A. Scott. 1979. Sorption of hydro-
phobic pollutants on natural sediments. Manuscript in publication.
(Personal communication).
Kay, B. D., and D. E. Elrick. 1967. Adsorption and movement of Lindane
in soils. Soil Sci. 104:314-322.
Kenaga, E. E. 1975. Partitioning and uptake of pesticides by biological
systems. In Environmental Dynamics of Pesticides (eds. R. Haque and
V.H. FreedJ7 Plenum Press, N.Y. pp. 217-275.
King, P. H., and P. L. McCarty. 1968. A chromatographic model for pre-
dicting pesticide migration in soils. Soil Sci. 106:248-261.
34
-------
Knight, B. A. G., J. Coutts, and T. E. Tomllnson. 1970. Sorption of ionized
pesticides by soil. In Sorption and Transport Processes 1n Soils. Soc.
Chem. Ind. (London), pp. 54-62.
Konrad, J. G.,and G. Chesters. 1969. Degradation 1n soils of clodrin,
an organophosphate Insecticide. J. Agri. Food Chem. 17:226-230.
Koren, E.. G. L. Foy, and F. M. Ashton. 1969. Adsorption, volatility, and
migration of thiocarbamate herbicides in soil. Weed Sci. 17:148-153.
Lambert, S. H. 1966. The Influence of so1l-mo1sture on herblcidal response.
Weeds 14:273-275.
Lambert, S. M. 1967. Functional relationship between sorption in soil and
chemical structure. J. Agric. Food Chem. 15:572-576.
Lambert, S. M. 1968. Omega.(fl) a useful index of soil sorption aquilibria.
J. Agrlc. .Food Chan. 16:340-343.
Lambert, S.. M. , P". E, Porter,,and fl'., Schieifersteln. 1965. Movement ind
sorption of chemicals applied to soils. Weeds 13:185-190.
Langmulr, I. .1918. J. Amer.'Chem; Soc. 40:1361. As cited by Llndstrom
et al. See ref. 21.
Lapidus, and Nv R. Amundson. 1952. Mathematics, of adsorption fh beds.
VI. The effect of longitudinal diffusion 1n Ion exchange and chromato-
graphic columns. J. Phys. Chem. 56:984-988.
Leenheer, J. A., and J. L. Ahlrich. 1971. A kinetic and equilibrium study
of the adsorption of carbaryl and parathion upon soil organic matter
surfaces. Soil Scl. Soc. Amer. Proc. 35:700-704.
Leo, A., C. Hanch, and D. El kins. 1971. Partition coefficients and their
uses. Chem. Rev. 71:525-616.
Leonard, R. A., G. W. Langdale, and Wl G. Flemming. 1979. Herbicide runoff
from upland piedmont watersheds—Data and Implications for modeling
pesticide transport. Jour. Environ. Qua!. 8:223-229.
Liestra, M. 1970. Distribution of 1,3-d1chloropropene over the phases of
soil. J. Agri. Food Chem. 18:1124-1126.
Lindstrom, F. T., R. Haque, and W. R. Coshow. 1970. Adsorption from
solution. III. A new model for the kinetics of adsorption-desorptlon
processes. J. Phys. Chem. 74:495-502.
Liu, L. C., H. Cibes-Viade, and F. &. S. Koo. 1970. Adsorption of ametoyne
and ditiron by soils. Weed Sc1. 18:470-474.
Macnamara, G., and S. J. Toth. 1970. Adsorption of Llnuron and malathion by
soils and clay minerals. Soil Sci. 109:234-240.
35
-------
Majka, J. T., and T. L. Lavy. 1977. Adsorption, mobility, and degradation
of cyamazine and diuron by soils. Weed Sci. 25:401-406.
McGlamery, M. D., and F. W. Slife. 1966. The adsorption and desorption ^
atrazine as affected by pH, temperature, and concentration. Weeds
14:237-239.
Metcalf, R. L., and P. Y. Lu. .1978. Partition coefficients as measures of
bioaccumulation potential for organic compounds. EPA report (in press).
Mukhtar, M. 1976, Desorption of adsorbed ametryn and diuron from solT^
and soil components in relation to rates, mechanisms, and energy of
adsorption reactions. Unpublished Ph.D. Dissertation, Univ. of Hawaii.
Mulkey, L. A., and J. W. Falco. 1977. Sedimentation and erosion control
implications for water quality management.
Murray, D. S., P. W. Santelman, and J. M. Davidson. 1975. Comparative
adsorption, desorption, and mobility of dipropetryn and prometryn in
soil. J. Agric. Food Chem. 23:578-582.
Obien, S. R., and R. E. Green. 1969. Degradation of atrazine in four
Hawaiian soils. Weed Sci. * 17:509-514.
Oddson, J. K., J. Ketey, and L. V. Weeks. 1970. Predicted distribution
of organic chemicals in solution and adsorbed as a function of position
and time for various chemical and soil properties. Soil Sci. Soc. Amer.
Proc. 34:412-417.
O'Connor, G. A., and J. V. Anderson. 1974. Soil factors affecting the
adsorption of 2,4,5-T. Soil Sci. Soc. Amer. Proc. 38:433-436.
Peck, D. E. 1977. The adsorption-desorption of diuron by fresh water sedi-
ments. Unpublished M.S. Thesis, Univ. of Calif. Riverside.
Rao, P. S. C. 1974. Pore-geometry effects on solute dispersion in aggre-
gated soils and evaluation of a predictive model. Ph.D. Dissertation,
Univ. of Hawaii.
Rao, P. S. C., and J. M. Davidson. 1979. Adsorption and movement of select-
ed pesticides at high concentrations in soils. Water Res. 13:375-380.
Rao, P. S. C., and J. M. Davidson. 1980. Unpublished Manuscript.
Rao, P. S. C., J. M. Davidson, and D. P. Kilcrease. 1978. Examination of
nonsingularity of adsorption-desorption isotherms for soil-pesticide
systems. Agron. Abstr. p. 34. (Manuscript submitted to Soil Sci. Soc.
Amer. Jour.)
36
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Rao, P. S. C., J. M. Davidson, R. E. Jessup, and H. M. Selim. 1979. Evalua-
tion of conceptual models for describing non-equilibrium adsorption-
desorption of pesticides during steady-flow in soils. Soil. Sci. Soc.
Amer. Jour. 43:22-28.
Rhodes, R. C., I. J. Belasco, and H. L. Pease. 1970. Determination of
mobility and adsorption of agricultural chemicals in soils. J. Agri.
Food Chem. 18:524-528.
Roberts, H. A., and B. J. Wilson. 1965. Adsorption of chlorpropham by dif-
ferent soils. Weed Res. 5:348-350.
Sanborn, J. R., B. M. Francis, and R. L. Metcalf. 1977. The degradation
of selected pesticides in soil: A review of published literature.
EPA-600/9-77-022.
Savage, K. E., and R. D. Wauchope. 1974. Fluometuron adsorption-desorption
equilibria in soils. Weed Sci. 21:106-110.
Schliebe, K. A., 0. C. Burnside, and T. L. Lavy. 1965. Dissipation of
Ami ben. Weeds 13:321-325.
Selim, H. M., J. M. Davidson, and R. S. Mansell. 1976. Evaluation of a
two-site adsorption-desorption model for describing solute transport
in soils. Proc. Summer Computer Simulation Oonf., Washington, D.C.
pp. 444-448.
Sheets, T. J., A. S. Crafts, and H. R. Drever. 1962. Influence of soil
properties on the phytotoxiclty of ^s-triazines. J. Agric. Food Chem.
10:458-462.
Sherbourne, H. R., and V. H. Freed. 1954. Adsorpton of 3 (p- chlorophenyl)-
1,1-dimethyl urea as a function of soil constituents. J. Agric. Food
Chem. 2:937.
Shin, Y. 0., J. J. Chodan, and A. R. Wolcott. 1970. Adsorption of DDT by
soils, soil fractions, and biological materials. J. Agri. Food Chem.
18:1129-1133.
Smith, C. N., R. A. Leonard, G. W. Langdale, and G. W. Bailey. 1978. Trans-
port of agricultural chemicals from upland piedmont watersheds.
EPA-600/3-78-056.
Snoeyink, V. L., W. J. Weber, Jr., and H. B. Mark, Jr. 1969. Sorption of
phenol and nitrophenol by active carbon. Environ. Sci. Technol.
3:918-926.
Swanson, R. A., and G. R. Dutt. 1973. Chemical and physical processes that
affect atrazine movement and distribution in soil systems. Soil Sci.
Soc. Amer. Proc. 37:872-876.
37
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Talbert, R. E., 0. H. Fletchall. 1965. The adsorption of some s-triaziries
in soils. Weeds 13:46-52.
Talbert, R. E., R. L. Runyan, and H. R. Baker. 1969. Behavior of amiben
and dinoben derivatives in Arkansas soils. Weed Sci. 17:10-15.
Thomas, J. M., and W. J. Thomas. 1967. Introduction to the Principles
of Heterogeneous Catalysis. Academic Press, N.Y.
van Bladel, R., and A. Moreale. 1976. Influence of soil properties on
adsorption of pesticide-derived aniline and p-chloroaniline. J. Soil
Sci. 27:48-57.
van Bladel, R., and A. Moreale. 1977. Adsorption of herbicide-derived
p-chloroaniline residues in soils: A predictive equation. J. Soil Sci.
28:93-102.
van Genuchten, M. Th., J. M. Davidson, and P. J. Wierenge. 1974. An evalua-
tion of kinetic and equilibrim equations for the prediction of pesticide
movement through porous media. Soil Sci. Soc. Amer. Proc. 38:29-35.
Wahid, P. A., and N. Sethunathan. 1978. A sample method to study pesticide
sorption in soils at short time intervals. Soil Sci. 126:56-58.
Walker, A., and D. V. Crawford. 1968. The role of soil organic matter in
adsorption of the triazine herbicides by soils. Isotopes and Radiation
in Soil-Organic Matter Studies., IAEC, Vienna pp. 91-108.
Walker, A., and D. V. Crawford. 1970. Diffusion coefficients for two
triazine herbicides in six soils. Weed Res. 10:126-132.
Ward, T. M., and K. Holly. 1966. The sorption of s-triazines by model
nucleophiles as related to their partitioning between water and
cyclohexane. Jour. Colloid. Interface Sci. 22:221-230.
Wauchope, R. D. 1978. The pesticide content of surface water draining
from agricultural fields: A Review. Jour. Environ. Qual. 7:459-472.
Weber, J. B. 1966. Molecular structure and pH effects on the adsorption
of 13 s-triazine compounds on montmorillonite clay. The Amer.
Minerologist 51:1657-1670.
Weber, Jr., W. J., and J. P. Gould. 1966. Sorption of organic pesticides
from aqueous solution. Adv. Chem. Series 60:280-305.
Wildung, R. E., G. Chesters, and D. E. Armstrong. 1968. Chloramben (amiben)
degradation in soil. Weed Res. 8:213-225.
Williams, J. D. H. 1968. Adsorption and desorption of simazine by some
Rothamsted soils. Weed Res. 8:327-335.
38
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Yaron, B., A. R. Swoboda, and G. W. Thomas. 196.7. ATdrin adsorption by
soils and clays. J. Agrl. Food Chem* 15:671-675.
39
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SECTION 5
PESTICIDE TRANSFORMATIONS IN SOILS
L.T. Ou, J.M. Davidson, P.S.C. Rao, and W.B. Wheeler
Three important aspects of pesticide degradation are: mechanism, path-
way, and rate of degradation. Photochemical, chemical, and microbiological
transformations are generally considered to be the principal pesticide de-
gradation mechanisms in soils. Among these, photodecomposition is of little
practical significance for pesticides located below the soil surface, while
microbiological transformations are of major importance because they result
in an extensive breakdown (H2O, CO2, and simple inorganic ions) of the pesti-
cide molecule.
AEROBIC AND ANAEROBIC DEGRADATION
Soil and environmental factors that determine pesticide degradation
rates are: soil type, soil-water content, pH, temperature, clay and organic
matter content. The most profound and yet frequently unpredictable factor in-
fluencing pesticide degradation rate is soil microbial activity. The nature
and composition of the microbial populations as well as the soil environment-
al variables that control their activity are important factors in pesticide
degradation. Temperature and soil-water content are two environmental fac-
tors that have been intensively studied in this regard. In general, these
studies have shown that increased microbial activity at higher temperatures
have enhanced pesticide degradation. For example, picloram herbicide degra-
dation was low at 5°C, while more extensive degradation occurred at 30°C or
50°C depending on soil type (Guenzi and Beard, 1976). The half-lives of pes-
ticides have also been shown to increase with decreasing soil-water content
(Guenzi and Beard, 1976; Walker, 1976a,b). Higher adsorption and lower
microbial activities may be responsible for the reduced degradation at low
soil-water contents. At high soil-water contents (approaching saturation),
pesticide degradation rates may be determined by the relative rate of decom-
position under aerobic versus anaerobic conditions.
The soil surface is generally aerobic. However, as the soil-water con-
tent approaches saturation and/or the surface becomes submerged under water,
the availability of atmospheric oxygen is reduced. Oxygen trapped in the
soil is quickly depleted by the activity of the aerobic soil microorganisms
for these cases. Thus, within a short period of time, the soil environment
becomes anaerobic. Except for a thin layer (few mm thick) at the water-soil
surface interface, the soil changes from an oxidized state to that of a re-
duced state (Sethunathan, 1973). Anaerobic environments are also encountered
40
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when soil, is carried by runoff water and results in sediment at the bottom
of ponds, streams, rivers or other bodies of water. The rates and pathways
of pesticide degradation under unaerobic;conditions (flooded or submerged)
may differ significantly from those for aerobic conditions.
Some compounds when present 1n a highly oxidized state tend to resist
microbial degradation, but are susceptible to reductive decomposition under
anaerobic conditions {Goring et al;, 1975). for example, chlorinated.hydro-
carbon and organophosphorus insecticides degrade sTowly under aerobic condi-
tions but degrade more rapidly under an unaerobic environment (MacRae et al.,
1967; Raghu and MacRae, 1966; Castro and Yoshida, 1971; Guenzl and Beard,
1967, 1968; Sethunathan and MacRae, 1969; Sethunathan, 1973). Also, the tr1-
fluralln herbicide has been reported to degrade more rapidly 1n anaerobic
rather than aerobic soils (Parr and Smith, 1973). Pesticide mineralization,
as indicated, by COg production,.may be low for anaerobic conditions, but sub-
stantial quantites of intermediate metabolites frequently accumulate in an-
aerobic soils. Pesticide metabolites, equally or more toxk than parent
compound (ODD and DOE from DDT), produced 1n fr reduced environment on the
other hand, are. more susceptible to decomposition under oxidative than under
reducti ve conditions..
QUANTITATIVE ASPECTS OF PESTICIDE TRANSFORMATIONS
Numerous reviews are presently available, that deal with transformations,
metabolic pathways,.and persistence,, and to some extent half-lives «f pesti-
cides and related toxic organic chemicals la soils (Kearny and Helling, 1969;
Helling et al., 1971; Edwards, 1972; Crosty, 1973* Srthunatharii 1973;
Hastumura, 1974; Howard et al., 1975; Kaufmanj 1976; Sanborn et al., 1976;
Laveglia and Dahn, 1977). However, none of these reviews systematically dis-
cuss pesticide degradation kinetics or attempt to relate soil and environ-
mental properties, with rates of pesticide degradation in soils. Hamaker
(1966, 1972) has presented an excellent discussion of the quantitative aspects
of pesticide degradation in soil. Two basic types of rate models considered
were:
where, C is concentration (mg/g), t Is time (days), k. is kinetic rate coeffi-
cient (days-1), n 1s order of the reaction, Vmx is maximum rate approached
with Increasing concentrations, and a is a constant. It should be noted that
when n = 1, Eq. [5-1] reduces to the case of. first-order kinetics, while
Eq. [5-2] reduces to the case of zero-order kinetics When C » a. Goring et
al. (1975) compared pesticide degradation processes, using these rate equa-
tions. Walker (1976a,b) reported that the degradation of slmailne, prome-
tryne, and linuron herbicides in field soils followed first-order kinetics
(i.e., nal in.Eq. [5-1].
[5-1]
a§3 *
[5-2]
41
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Among soil and environmental factors, soil temperature and soil-wairr
content are the two most important factors, that influence pesticide degra-
dation rates in soils. Soil temperature and soil water-content influence
soil microbial activity which, in turn, governs the biological degradation
rate. Moreover, chemical and photochemical decomposition, and volatili-
zation of pesticides are also affected by the changes of soil temperature
and soil-water content. Walker (1974, 1976a,b, 1978a,b) used the relation-
ship between degradation rate coefficient ( k]) and temperature, and rate
coefficient and soil-water content to predict solvent-extractable parent
chemical disappearance rates of a number of herbicides under field condi-
tions. Assuming first-order kinetics, the half-lives or k] values for
herbicides in soils under a range of controlled conditions can be expressed
in two equations:
where, A and B are constants, t-j^' t'l/2' ar)d f'lfZ are half-lives at tem-
peratures T, T], and T2, respectively, M is soil moisture content aE is
Arrhenius activation energy constant, and-R is gas constant (1.984 x 10~3
kcal/mole-deg). Using these relationships, Walker and coworkers simulated
herbicide disappearance rate in the field with a fair success. Predicted
values were generally higher than observed values. Smith and Walker (1977)
developed an empirical expression that describes the dependence of pesticide
degradation rates on soil temperature plus soil-water coefficient. They
assume a linear increase in the rate coefficient (k-]) with increasing value
of the product (M * T), where M is the soil-water content, and T is soil
temperature. This relationship can be stated as follows:
where, a and 3 are empirical constants specific to a given pesticide, but not
necessarily for a given soil type. Smith and Walker (1977) used Eq. [5-5] to
successfully describe herbicide asulam degradation under field conditions.
Given the vast complexity of the soil-water-pesticide systems, approaches
given by Eq. [5-5] may be sufficiently accurate to describe the pesticide
degradation rate dependence on soil temperature and soil-water content.
Pesticide degradation rates under field conditions have generally been
measured as the rate of disappearance of organic solvent-extractable parent
compound. Few reports include quantitative data on rates of metabolite accu-
mulation from pesticide degradation in soils. Two specific drawbacks should
be kept in mind when organic solvent-extractable parent compound disappear-
ance rate is used as a measure of pesticide degradation. First, even though
the parent compound itself may have degraded, significant amounts of various
metabolites may accumulate. Some of these metabolites could be equally or
more toxic and/or persistent in soils. Secondly, a significant portion of
the parent compound and/or its metabolites may become "bound" to the soil.
Consequently, in such cases the degradation rate measured from disappearance
of parent compound would over-estimate the true degradation rate. An
[5-4]
[5-3]
k-. - aMT + 3
[5-5]
42
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alternate method of measuring pesticide degradation rate in soils, under Tab-
oratory Incubation conditions, has been to monitor the rate of 14c02 evolu-
tion from soils incubated with He-labeled pesticides. Depending upon the
specific position of the Unlabel on the pesticide molecule, evolution
rate may or may not represent the total mineralization rate. The mineraliza-
tion rate measured using l^C-ring labeled compounds is generally lower than
parent compound disappearance rates.
BOUND PESTICIDE RESIDUES
In most studies dealing with persistance of pesticides 1n soils, the
pesticide residual level remaining in the soil has been measured by extrac-
tion with organic solvents. However, use of ^C-labeled pesticides in these
experiments has revealed that losses from degradation and volatilization plus
the l^C-labeled pesticide extracted by organic solvents cot/Id not account for
100? of the added 14c-pest1cide. A substantial fraction of applied pesticide
was apparently bound to the soil and could not be recovered by exhaustive
extraction with organic solvents. The amount of bound pesticide residues Is,
therefore, determined by combusting a. soil sample after exhaustive solvent
extraction and quantifying the carbon dioxide produced.
Over the last few years considerable attention has been given to bound
pesticide residues. The most comprehensive work has taken the form of the
book entitled "Bound and Conjugated Pesticide Residues" edited by Kaufman et
al. (1976-). This review 1s a compilation of papers presented at a symposium
sponsored by the Pesticide Chemistry Division of the American Chemical
Society. A working definition of a soil-bound pesticide residue is "that
unextractable and chemically unidentifiable pesticide residue remaining in
fulvlc acid, humlc acid, and^iunyin fractions of the soil after exhaustive
sequential extraction with noripolar and polar organic solvents."
The presence of these bound residues has focused new attention on pesti-
cides perslstance. Pesticides previously classified as nonpersistant 1n soils
may actually be more persistant than originally thought. Johnson and Stans-
bury (1965) reported that the half-Hfe of carbaryl Insecticide in soil was
about 8 days and that this Insecticide was totally degraded within 40 days.
However, Kazano etal. (1972) reported that substantial amounts (ranging
from 20 to 60% of the original radioactivity) of the ^c-carbaryl remained in
the soil even after 32 days of Incubation. Bartha (1971) and Chlska and
Kearny (1970) found the bound residues of herbicide propanil to range from
50 to 801 of that applied. Similar findings for fonofos were reported by
Flashlnski and Lichtenstein (1974). Ambrosl etal. (1977) have studied the
perslstance and metabolism of the organo-phosphate insecticide phosalone In
two soils, and found rapid disappearance of this pesticide to be accompanied
by a large build-up of bound residues.
The amount of bound pesticide residues appears to Increase with time
(Katan et al., 1976; Lichtenstein et al., 1977). The bound residues gradually
reached about 40, 10, 35, and 30t, respectively* for methyl parathion, dlel-
drin, dyfonate, and DDT during a 28 day incubation (Lichtenstein et al.,
1977). The exact mechanisms for pesticide binding in soils are not well
understood at this. time. The binding of parathion and propanil apparently
-------
involves soil microorganisms. The amount of bound residues declined drasti-
cally in sterile soils and also at low temperatures (Chiska and Kearny, 1970;
Katan et al., 1976). However, binding..o.f fonofos did not depend upon soil
microbial activity (Lichtenstein et al., 1977). Soil organic matter also
appears to play an important role in pesticide binding to soils. The amount
of bound pesticide residue was higher in soils with a higher organic matter
content than in those soils containing a low organic matter content (Katan et
al., 1976). Furthermore, a majority of bound carbaryl residue was found to
be linked to humic substances (Kazano et al., 1972). Fractionation of the
bound residues of phosalone insecticide showed (Aimbrosi et al., 1977) that
the distribution of decreased in the order of fulvic acid > humic acid >
humin; under flood conditions, however the 14C distribution was altered to
.fulvic'acid V' humin > humic acid. Based on such findings, a two-step binding
mechanism based on a microbial process and a physical-chemical process that
leads to a strong covalent-type bonding of pesticides through organic sub-
stances.in soil have been postulated (Katan et al., 1976; Hsu and Bartha,
1976).
ESTIMATING PESTICIDE DEGRADATION AND MINERALIZATION RATES
In this review, pesticides were divided into three main classes based on
their agricultural use: herbicides, insecticides and fungicides. Chemicals
within each class were subdivided into groups according to their chemical
structure. For example, herbicides were grouped as phenoxyalkanoic acids,
dinitroanilines, and s-triazines while insecticides were grouped as carba-
mates, chlorinated hydrocarbons, and organophosphates. Because of the number
of chemicals and the volume of literature available, only pesticides which
were now in wide use or were used widely in the past were considered. Chemi-
cals with structural similarities tend to have similar physicochemical proper-
ties and exhibit similar biological responses. Hence, degradation rates in
soils for the chemicals not listed in this review can be estimated using the
data for structurally related compounds. Degradation rate constants were re-
ported, if already shown in the literature. However, the majority of the
literature did not provide rate constants and/or half-lives. In these cases, ,
rate constants and half-lives for pesticides in soils were calculated by the
reviewers assuming that degradation followed first-order kinetics. The fol-
lowing, equations were used to calculate rate coefficients and/or'half-lives:
Where C] and C? are pesticide concentrations at time ti and t2 (days), k-| is
rate constant (day-!), and t]/2 is half life (days). Attempts were not made
to calculate k-| and ti/2 for pesticide degradation rates which were originally
expressed in regression equation form. Rate constants for each pesticide were
divided into aerobic, and anaerobic (including flooded with water) incubation.
Rate constants and half-lives from laboratory studies were expressed in two
ways: (1) as solvent-extractable parent-chemical disappearance rates and
[5-6]
_ 0.693
1/2 " k.
[5-7]
44
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(2) mineralization.rates. In attempts to correlate key soil properties with
pesticide degradation rates, the following properties were used: pesticides
concentration, organic matter and clay content, pHr temperature, soil-water
content, and soil depth (field studies only). These properties are listed
along with calculated rate constants and half-lives. Arrhenius activation
energy constants were listed if available.
The common and chemical name of each pesticide considered 1n this manu-
script 1s presented in Table 5-1.
Herbicides
2,4-D and 2,4,5-T--
Phenoxyalkanoic acid herbicides 2,4-0 and 2,4,5-T are widely used to
control broad leaf weeds,. Microbial.degradation appears: to be the major fac-
tor 1n the disappearance of 2,4-D and 2,4,5-T as well as other phenoxyalkanolc
acid herbicides in soils and water~ Some soil microorganisms:can utilize
2,4-D as their sole source of energy. For example," 2,4,5-T was degraded to
CO2, H2O and chloride by two.mixed bacteria through cometabollsm 1n the pres-
ence of a second carbon source (Ou and Sikka, 1977). Very little degradation-
has been shown to occur.in sterile soils treated with either herbicide. Sol-
vent extractable'2,4*-D disappearance rates (k]) in soils incubated 1n the
laboratory under aerobic conditions were 2.1.x 10~2 to 1.7 x TO"! day-' with
an average of (6.6 * 4.9) x. 10"2 day-1 (Table Bl). This corresponds to half
lives of 4 to 34 days with an average of 16 ± 9 days. The 2,.4-D degradation
rate appeared to be related to total soil bacterial population which probably
reflects the higher 2,4-D degrading bacteria population in these soils.
Solvent-extractable 2,4-D disappearance rates at field sites were generally
higher than these observed for laboratory studies. The half lives for 2,4-D
in the field-were < 1 to 15 days with an average of 5 t 5 days. This corre-
sponds to a k] of < 0.7 to 4.6 x 10-2 day-1 and an average of 3.6 ± 3.0 da!y->
(Table B2). Solvent extractable 2,4-D disappearance rates in flooded soils,
according to Yashida and Castro. (1975), were not significantly different from
those associated with aerated soils, i.e., 3.6 xlO"2 day-1 vs 5.0 x 10-2
day-1.
The mineralization rates for 2,4-D 1n soils Incubated in the laboratory
under aerobic conditions receiving 50 ppm or less were in the range of.2.8 x
10-2 to 6.3 x 10-2 day-1 with an average of (5.1 ± 1.2) x 10"2 day-1
(Table B3). The average rate coefficient corresponds to a half life of 11 to
25 days (15 ± 5 days). Both solvent extractable parent chemical disappear-
ance rates and mineralization rates for 2,4-0 under aerobic laboratory con-
ditions were similar. This suggests that the disappearance of 2,4-D 1n soils
was mainly due to complete degradation by the soil microorganisms.
The half lives for 2,4,5-T in soils 1n the laboratory were 14 to 64 days
with an average of 33 + 22 days. This corresponds to rate constants, ki, of
1.1 x 10-2 to 5.0 x 10-2 day-1 with an average of (2.9 ± 1.5) x 10-2 day-1
(Table B4). Solvent extractable 2,4,5-T disappearance rates in the field
were 9.9 x 10-3 to 7,4 x 10-2 day-' with an average of (3.5 ± 2.9) x .10:2
(Table B5) which corresponds to half lives of 8 to 31 days with an average
of.16 ± 11 days.
45
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Table 5-1. Common and Chemical Names of Selected Pesticides.
Common Name Chemical Name __
Aldrin 1,2,3,4,10,10-Hexachloro-l,4,4a,5,8,8a-hexahydro-l,4-
endo-exo-5,8-ctimethanonaphthalene
Atrazine 2-Chloro-4-ethylamino-6-isopropylamino-s-triazine
Bromaci1 5-Bromo-3-sec-butyl-6-methy1uraci1
Captan N-(Trichloromethy1thio)-4-cyclohexene-l,2-dicarboximide
Carbaryl 1-Naphthyl N-methylcarbamate
Carbofuran 2,3,Di hydro-2,2-dimethyl-7-benzofuranyl methyl carbamate
Chlordane 1,2,4,5,6,7,8,8-0ctachloro-2,3,3a,4,7,7a-hexahydro-
4,7-methanoindene (principal constituent)
2,4-0 2,4-Dichlorophenoxyacetic acid
Dalapon 2,2-Dichloropropionic acid
p,p'-DDT 1,1,l-Trichloro-2,2-bis(p-chlorophenyl) ethane
o.p'-DOT 1,1,l-Trichloro-2-(0-chlorophenyl)-2-(p-chlorophenyl)
ethane
Diazinon 0,0-diethyl 0-(2-isopropyl-4-methyl-6-pyrimidinyl)
phosphorothioate
Dicamba 3,6-Dichloro-0-anisic acid
Dieldrin 1,2,3,4,10,10-Hexachloro-6,7-epoxy-l,4,43,5,6,7,8,88-
Octahydro-1,4-endo-exo-5,8-dimethanonaphthalene
Diquat 6,7-Dihydrodipyrido (1,2-a:21,1'-C) pyrazidinium ion
Diuron 3-(3,4-dichlorophenyl)-l,1-dimethyl urea
Endrin 1,2,3,4,10,10-Hexachloro-6,7-epoxy-l,4,4a,5,6,7,8,8a-
octahydro-1,4-endo-endo-5,8-dimethanonaphthalene
Glyphosate N-(Phosphonomethyl) glycine
Fonofos O-Ethyl S-phenyl ethylphosphorodithioate
Continued
46
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Table 5-1.
(Continued)
Cannon Name
Chemical Name
Heptachlor
1,4 »5,6,7,8,8-Heptachloro-3a,7,7a-tetrahydro-4,7-
methanoindene
Lindane
f-1,2,3,4,5,6-Hexachlorocyclohexane
Ungron
3-(3,4-D1chlorophenyl)-lTmetho*y-l-methylurea
Malathion
S-[T ,2-Bi s(ethoxycarbony.1 )ethy 1 ]0 .Q-dlefchyl phosphoro-
dithioate
Methylparathion
0,0-Dfmettiyl O-para-n.litrophenyl phosphtfrOthtoate
Nttraltn
4-Methyl sulfonyl-2.6-rdln1trio-"N,N-d1 propylaniHtre..
Paraquat
1,11-Dimethyl-4,4'-bi pyrldy11um fon
Parathion
0,0-Dlethyl 0-para-nltropheriyl phosphorothioate
PCP
Pentech Vorophenol
Phorate
0,0-D1ethyl-S-;ethylth1p methyl phosphorodlthloate
PIcloram
4-Am1no-3,5,6-tr1chlorop1col1n1c. acid
S1maz1ne
2-Chloro-4,6-bts(etlty1am1no)-s-triaz1ne
2,4,5-T
2,4,5-Trich! orophenoxyaceti-c acid
TCA
Trichloroacetic acid
Terbacll
3-Tert-butyl-5-chloro-6-methyluraci1
Trifluralin
a,o,o-Tri f1uoro-2,6-d1n1tro-N,N-dipropy1-p-to!u1d1ne
47
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Atrazine and Simazine--
Atrazine and simazine are widely used s_-triazine herbicides in agricul-
ture. Application rates of atrazine and simazine in field studies were
generally in the range of 1 to 4.5 kg/ha (0.4 to 2 vg/g). Half lives for
atrazine in the field ranged from 12 to 53 days with an average half lite of
20 ± 11 days. Rate constants, k-], were in the range of 1.3 x 10~2 to 5.3 x
10-2 day-1 with an average of (4.2 ± 1.4) x 10~2 day-1 (table B6). Half
lives and k] values were calculated based on first-order kinetics. Half
lives and ki for simazine in the field were 11 to 246 days (64 ± 60 days) and
2.8 x 10-3 to 6.2 x 10~2 day-1 [(2.2 ± 2.1) x 10*2 day-1], respectively
(Table 87). Walker (1976a) reported that simazine degradation in his soil
appeared to follow first-order kinetics, as well as Michaelis-Menten enzyme
kinetics.
Solvent-extractable atrazine disappearance rates in soils incubated in
the laboratory tended to be higher than under field conditions. Half lives
and k] values for atrazine under aerobic laboratory incubation were in the
range ,of. 24 to.109 days (48 ± 33 days) and 6.3 x 10~3 to 2.9 x 10~2 day-1
[(1.9 ±'0:9) x-10-2 day—'3¦ respectively (Table B8). Incubation tempera-
tures were 13.2 to 31.2°C. Half lives were shortened as the incubation tem-
perature increased. Half lives at 13.2°C and 31.2°C were 109 and 35 days,
respectively (Zimdahl, et al., 1970). Half lives at 95°C were less than
3 days (Hance, 1969). Solvent extractable simazine disappearance rates and
half lives in soils held under conditions of aerobic laboratory incubation
were 16 to 234 days (75 ± 55 days), and-3.0 x 10" 3 to 4.3 x 10-5 day-1, re-
spectively [(1.4 + 1.0) x 10"2"day-l]. Arrhenius activation energy constants
for atrazine and simazine were 10.8 and 9.2 to 13.7 kcal/mole, respectively
(Walker, 1976a,b; Zimdahl et al., 1970).
Mineralization rates for atrazine in soils were much lower than the sol-
vent extractable parent chemical disappearance rates. In fact, mineraliza-
tion rates for 14c-ring labeled atrazine were 2.0 x 10-4 to 6.7 x 10-5 day-1
corresponding to half lives of 3,465 to 10,343 days (Table B10). No informa-
tion regarding simazine mineralization rates was reported.
Trifluralin and Nitralin—
Dinitroaniline herbicides, trifluralin and nitralin are generally incor-
porated into a soil for preemergence control of specific grasses and broadleaf
weeds. Trifluralin concentrations used in laboratory studies were in the
range of 1 to 10 ug/g. At these'concentrations, the solvent-extractable tri-
fluralin disappearance rates in soils under aerobic incubation generally
followed first-order kinetics, and the half lives and rate constants were in
the range of 33 to 375 days (132 ± 109 days) and 1.8 x 10*3 to 2.1 x 10~2
day-1 (Table Bll), respectively [(8.4 + 5.5) x 10-3 day"1]. Arrhenius activa-
tion energy constants were 14.9 to 16.5 Kcal/mole. Under anerobic incubation,
including flooded conditions, solvent-extractable trifluralin disappearance
rates were generally higher than under aerobic incubation, and were in the
range of 9.9 x 10*3 to 2.0 x 10"! day-1 (Table B12). This corresponds to half
lives of 4 to 70 days (average 28 days). Increasing temperature and soil
moisture enhanced trifluralin volatilization in soils which enhanced the sol-
vent extractable trifluralin disappearance rate. Mineralization rates for
'^C-labeled trifluralin (labeled at -CF3) were very low and were in the range
48
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of 1.0 x 10" 3 to 1.7 x 10"3 day-1 corresponding to 405 to 683 days with an
average of 544 days (Massersmlth et al.» 1971). Solvent extractable triflur-
alin disappearance rates In field soils generally followed first-order
kinetics, and were 1n the range of 1.0 x 10-2 to-4.7 x 10-2 day-1 (Table B13)
[(2.0 ±1.3) x 10-2 day-'] corresponding to 15 to 69 days (46 ± 19 days). It
was reported recently that solvent extractable trifluralln disappearance rates
followed complex first-order kinetics better than simple first-order kinetics
(Lafleur et al., 1978; Zimdahl and Gv
-------
(Usorol and Hance, 1974). The Arrherius activation energy constants for
linuron were in the range of 10.9 to 13.1 kcal/mole. The average solvent ex-
tractable linuron disappearance rate constant under field conditions in one
report (Smith and Edmond, 1975) was (3.4 t 1.4) x 10-3 day"' (Table B21)
which corresponds to an average half life of 230 ± 88 days.
Solvent extractable diuron disappearance rate constants in the field were
in the range of 1.3 x 10*3 to 5.2 x 10-3 day-1 (Table B22) with an average of
(3.1 + 1.8) x 10-3 day-1 corresponding to half lives 133 to 657 days with an
average of 328 ± 212 days. No degradation rates for diuron from laboratory
studies could be obtained or derived. Reports for diuron degradation in field
soils were primarily bioassays for determining pesticide residues. By com-
paring the average solvent extractable linuron disappearance rate in the
field, it appears that the solvent extractable diuron disappearance rate in
laboratory experiments would be somewhat lower than that for linuron.
Dicamba--
Dicamba, a benzoic acid herbicide, is used as a selective herbicide for
pre- and post-emergence control of annual broadleaf and grassy weeds in
cereals. The half lives for dicamba disappearance from soils incubated in the
laboratory under aerobic conditions were 1n the range of -0 to 32 days with an
average of 14 ± 12 days. This corresponds to solvent extractable dicamba dis-
appearance rate constants of 2.2 x 10-2 to - « day*1 (Table B23). Even
though dicamba rapidly disappeared from soils, especially at field capacity
moisture levels (Smith, 1973) and for temperatures above 15°C (Smith and
Cullimore, 1975), mineralization rates were much lower with half lives of
309 days for 14c-ring labeled dicamba and 147 days for l^C-carboxy-labeled
dicamba. Substantial amounts of the metabolite 3,6-dichlorosalicylic acid
were accumulated in soils (Smith, 1974). The Arrhenius activation energy was
calculated to be 17.1 + 6.1 kcal/mole for the temperature range 10° to 30°C.
Degradation rates from 30 to 40°C were either the same or lower (Smith and
Cullimore, 1975). No anerobic incubation studies were reported.
Solvent extractable dicamba disappearance rate constants for field condi-
tions were in the range of 7.2 x 10-2 to 1.0 x 10-1 day-1 with an average of
(9.3 ± 1.5) x 10-2 day-1 (Table B24) corresponding to half lives 6 to 10 days
(8 ± 1 day).
Picloram--
Picloram is a substituted picolinic acid herbicide and is the only promi-
nant member of the family of pyridine derivatives that has been studied exten-
sively. The solvent extractable picloram disappearance rate constants for
soils incubated in the laboratory under aerobic conditions were in the range
of 3.8 x 10~4 to 2.4 x 10*2 day-' (Table B25) with an average of (6.9 ± 4.5) x
10-3 day-1 corresponding to'half lives of 29 to 1,804 days with an average of
201 ±312 days. Two of the degradation rate constants (out of 44) were ex-
tremely low. If these two rate constants were excluded, the average degrada-
tion rate constant would be (7.3 ± 4.3) x 10"3 day-1 corresponding to an
average half life of 138 + 93 days. Microbial degradation appears to be the
major process for the disappearance of picloram from soils since very little
degradation occurred in sterile soils (Goring and Hamaker, 1971). Increasing
50
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organic matter and temperature as well as adequate moisture Increased dis-
appearance rates. Arrhenius activation energy was reported to be 4.5 to 6.3
kcal/mole (Meikle et al.,. 1973). Solvent extmtable plcloram disappearance
rate constants under flooded conditions appeared to be the same as for those
under aerobic.conditions, i.e., 4.7 x 10-3 day-t vs 4.3 x 10-3 day-1 (Yoshlda
and Castro, 1975)* Mineralization rates under aerobic conditions were much
lower than that of the disappearance rates. Mineralization rates for carboxy-
Cl4.iabeled plcloram 1n soils at temperatures of 15° to 30°C were In the
range of 5.0 x 10-6 to 4.0 x 10-3 day-1 (Table B26) with an average of (8.0 ±
8.9) x 10"4 day-1 corresponding to half lives of 175 to 69,300 days with an
average of 8,600 ± 15,845 days^ Because of this, 1t appeared that substantial
amounts of picloram metabolites could be accumulating in soils, although this
has not been reported.
The solvent extractable picloram disappearance rate constants m tne
field were in the range of 8.3 x 10-3 to 5.7 x 10-2 day-1 (Table B27) with an
average of (3.3 ± 1.7) x 10-2 day-I corresponding to half lives of 12 to 84
days with an average of 31 ± 24 days.
Dalapon and TCA—
Dalapon and.TCA are two. common chlorinated aliphatic ac.1d herbicides..
According to Namdeo. (1972), the average half life for dalapon in soil was
15 days corresponding to solvent extractable dalapon disappearance.rate con-
stants of 4.7 x 10-2 day-1 (Table 823). The solvent extractable TW dis-
appearance rate 1n solIs greatly increased as sotTmoisture and organic
matter contents increased (McGrath, 1976; Smith, 1974). Solvent extractable
TCA disappearance rate constants in soils were in the range of 8.9 x 10-3 to
1.2 x 10-1 day-1 (Table B2?) with an average of (5.9 ± 6.1) x 10-2 day-1 cor-
responding to half lives 4 to 144 days with an average of 46 ± 55 days. De-
gradation was mainly microbial. The average solvent extractable TCA
disappearance rate 1n the field* according to McGrath (1976) was 4.6 x 10"2
day-1 (Table B30) corresponding to a half life of. 15 days.
Glyphosate—
Glyphosate 1s a, broad spectrum post-emergence herbicide. Degradation of
glyphosate in soils is mainly a microbial process. Very little glyphosate was
degraded 1n sterile soil (Rueppel et al., 1977; Sprankle et al., 1975). De-
gradation rates including solvent extractable glyphosate disappearance rates
and mineralization rates varied greatly from one soil to another depending up-
on soil type. The solvent extractable glyphosate disappearance rate constants
were from 5.3 x 10-3 to 2.3 x 10-1 day-' (Table B31) with an average of (1.0
± 1.2) x 10-1 day-1 corresponding to half lives from 3 to 130 days with an
average of 38 ± 53 days. The mineralization rate constants for glyphosate
were from 1.3 x 10~4 to 2.3 x 10_2 day-1 (Table B32) with an average of (8.6
± 8.0) x 10"3 day-1 corresponding to half lives of 30 to 5,177 days with an
average of 903 ± 1,732 days. The mineralization rates for 14c-glyphosate la-
beled at various positions were all about the same (Rueppel et al., 1977).
Bound residues were formed and one metabolite, amlnomethylphosphonic acid, was
detected in soils (Nontiura and Hilton, 1977; Rueppel et al., 1977). No degra-
dation data obtained in the field have been reported.
51
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Diquat and Paraquat--
Oiquat arid paraquat are the two most important bipyridylum herbicides.
Theyiare used as salts, diquat as the dibromide and paraquat as the dichlo-
ride. Both diquat and paraquat are rapidly and completely adsorbed to soil
particles. Even though a number of soil microorganisms including bacteria
and fungi could utilize either herbicide as a nitrogen source or a sole car-
bon source in synthetic media (Burns and Audus, 1970; Baldwin et al., 1966;
Tu and Bollen, 1968'), the disappearance of the herbicides in soils was slow
in soils. Strong adsorption to soil clays and organic matter apparently
rendered them inaccessible to soil microorganisms. Although a few publica-
tions reported degradation of diquat and paraquat in soils, one report could
be used for calculating disappearance rate constants (Fryer et al., 1975).
The average solvent extractable paraquat disappearance rate in the field was
1.5 x 10-3 day-1 (o - 4.9 x 10-4 day-1) corresponding to a half life of
4,747 days. The solvent extractable paraquat disappearance rate constants
for a sandy loam soil in laboratory were 9.3 x 10-4 to 2.2 x 10-3 day-1 with
an average of 1.6 x 10-3 day-1 corresponding to half lives 316 to 743 days
with an average of 487 days.
Insecticides
Parathion, Methylparathion and Diazinon—
Parathion, methylparathion and-diazinon are the three'most widely used
organophosphorothioate insecticides. The insecticides can be hydrolyzed bio-
logically or chemically-in soils. However, the microbial hydrolysis rate is
much'higher than'the chemical hydrolysis rate (Bro-Rasmussen et al., 1968;
Kishk et al., 1976; Saltzman et al., 1976; Sethunathan and McRae, 1969; Yaron,
1975). Only microbial degradation leads to complete detoxication of the chem-
icals to C02, H2O and simple inorganic phosphate. The solvent extractable
parathion disappearance rate constants for soils under laboratory aerobic in-
cubation were in the range of 5.0 x 10-3 to 3.3 x 10-2 day-1 (Table B33) with
an average of (2.1 ± 1.4) x 10-2 day-1 corresponding to half lives 18 to
78 days with an average.of 35 ± 29days. Parathion was degraded very slowly .
in air dry soils with an average half life of 244 ± 108 days (Mingelgrin and
Yaron, 1974). Solvent extractable parathion disappearance rate constants in
flooded soils were higher than in aerated soils, and were in the range of
3.2 x 10"2 to 4.3 x 10-1 day-1 (Table B34) with an average of (1.1 ± 1.2) x
10-1 day-1 corresponding to half lives of 2 to 22 days with an average of
11 ± 7 days. The solvent extractable parathion disappearance rate constants
•in the field were in the range of 2.4 x 10"2 to 2.3 x 10-1 day-1 (Table B35:)
with an average of (5.7 ± 5.8) x 10-2 day-1 corresponding to half lives of
3 to 29 days with an average of 18 ± 8 days. No mineralization rates for
parathion in soils were reported. However, bacteria that completely degraded
parathion to CO2, and H2O were isolated. (Munnecke and Hsieh, 1974; Sid-
daramappa et al., 1973).
The average solvent extractable methylparathion disappearance rate con-
stants from two soils incubated aerobically in the laboratory was 1.6 x 10"!
day-1 (Table B36) corresponding to an average half-life of 5 days. The sol-
vent extractable methylparathion disappearance rate constant in the field,
according to Lichtenstein and Schulz (1964), was 4.6 x 10-2 day-1 correspond-
ing to a half life of 15 days.
52
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Substantial amounts of both Mc-parathfon and I^C-methylparathlon became
bound to soils (Katan et al., 1976; Lichtenstein et al., 1977). If l^C-acti-
vlty bound to soil was considered to be parent chemical> the solvent extract-
able parent chemical disappearance rate will be lower. For example, the
solvent extractable ^C-pa rath ion disappearance rate constant 1.n Piano silt
loam was 8.9 x 10-3 day-1, but after taking into account the bound residue 1t
was 5.0 x 10-3 day-1 (Katan et al., 1976). The solvent extractable 14c-
methylparathlon disappearance rate constant 1ti Piano silt loam was 9.5 x 10~?
day-), and when bound residues were considered the rate constant was 2.5 x
10-2 day-1 (Lichtenstein et al., 1977).
Solvent extractable diazinon disappearance rate constants 1n soils incu-
bated in the laboratory under aerobic conditions were in the range of 5.6 x
10*3 to i .0 x 10-i day-1 (Table B3.7) with an average of (2.3 ± .2.5) .x 10*2
day-1 corresponding to half lives 7 to 125 days with an average of 48 s
30 days. The average Arrhenius activation energy constant under aerobic con-
ditions was 12.0 ± 1.8 kcal/mole (a. calculated, value in Getzirr; 1968). The
mineralIzat.ipn rate constant in soil incubated under aerobic conditions, was
2.2 "x. 10-2 'corresponding to. a.half ...life 32 days /(iGetzia,... 19.67;):*. . A. dlazl.non.
hydrolysis product, 2-isbprbpyl-4-methyl-6-hydr6^y-pyrimidine was detected.
Nonextractable. l^residues were, foiled steadily,, arid, about 354 of the total
14C-act1vity was bound to Sultan silt loam in 16 weeks. Diazinon disappeared
rapidly from flooded soils, the solvent extractable diazinon disappearance
rate.constants were ^0 x 15T?vtp Mb-l-tlajH- (Table B38) with an averaige
of - (9,.6 ±,6vl.) x l0-2.day-1 cojr^sfionding to Jialf Tiyes 4 to ;i7 ^ays 'with. an
average of 10 ± 5 days. Hi&eVef,''''mflrieralIzatioh' rates' in flooded soils were
very low with an average of (1.1 ± 0.3) x 10*4 day-1 corresponding to a half
life of 6,833 ± 1,858 days (Sethunathan and McRae, 1969; Sethunathan and
Yoshlda, 1969). This discrepancy indicated that significant amounts of metab-
olites could be accumulating 1n the flooded soils. In fact, over 302 of
metabolites 2-1sopropyl-4-methyl-6-hydroxvpyrimid1ne were detected after
9 days of Incubation (Laanio et al., 1972). No degradation rates for field
cases were reported.
Fonofos, Malathion and Phorate--
Fonofos, malathion and phorate are commonly used organodlthlophosphorus
Insecticides. The solvent extractable fonofos disappearance rate constant
for a soil incubated in the laboratory under aerobic conditions was 2.8 x 10~2
day-1 corresponding to a half life of 25 days (Lichtenstein et al., 1977).
Bound residues from 14c-1abeled fonofos were rapidly formed in soil, and 35%
of the applied ^-activity was non-extractable after 28 days. Solvent"
extractable fonofos disappearance rates 1n the field appeared to follow com-
plex, first-order kinetics—an initial rapid, disappearance followed by a slow-
er disappearance rate. Average ti/2 and tV«2 values (IC11gemg1 and Terriere,
1971; Schutz and Lichtenstein, 19717 were z4 and 102 days (Table 839)., re-
spectively. If simple first-order kinetics were employed, the average sol-
vent extractable fonofos disappearance rate constant was 1.2 x 10-2 day-1
(Table B40) corresponding to a half life 60 days.
Microbial degradation and chemical hydrolysis.are,the two main factors
contributing to the disappearance of malathion from soils and water. Chemical
53
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hydrolysis increased as pH increased (Konrad et al., 1969; Walker and
Stojanovic, 1973). Malathion disappearance was much more rapid in non-
sterile soils than in sterile soils. Solvent extractable malathion disappear-
ance rate constants in nonsterile soils were in the range of 3.3 x TO"' to
2.5 day-1 (Table B41) with an average of 1.4 ± 1.0 day-' corresponding to half
lives of 0.2 to 2.1 days with an average of 0.8 + 0.7 day. Malathion also
disappeared rapidly in water and sediment with half lives of 3 and 2 days,
respectively (Walker, 1976).
Solvent extractable phorate disappearance rate constants in soils in the
laboratory under aerobic conditions varied greatly (Getzin and Chapman, 1960;
Getzin and Shank, 1970), (8.9 ± 1.2) x 10-2 day-1 vs 8.4 x 10-3 day-1
(Table B42). The difference may be due to the analytical methods used since
the average solvent extractable phorate disappearance in the field was (1.0 ±
0.3) x 10-2 day-1 (7.9 x 10~3 to 1.4 x 10"2 day-1 (Table B43) corresponding
to an average half life of 75 ± 18 days. GC was used for all field studies,
and the half life of 82 days reported in one of the laboratory studies also
used GC for analysis.
Carbaryl" and Carbofuran—
.The methyl carbamate insecticides carbaryl and carbofuran are broad spec-
trum systematic pesticides. The degradation rate for carbofuran in soils
appears to increase as the soil pH increases and organic matter content de-
creases (Caro et al., 1973; Getzin, 1973). The solvent extractable carbofur-
an disappearance rate constants in soils incubated in the laboratory under
aerobic conditions were in.the ranae of 7,5 x 10-3 to 1.1 x 10-1 with an
average of (4.7 ±4.1) x 10"2 day-1 (Table B44) corresponding to half lives
of 6 to 93 days with an average of 37 ± 35 days. The average solvent ex-
tractable carbofuran disappearance rate constant in flooded soils was (2.6 ±
1.3) x 10_2 (Table B45) corresponding to an average half life 44 ± 42 days
(Venkateswarlu et al., 1977). The degradation rate decreased as soil pH
decreased and organic matter content increased. The solvent extractable car-
bofuran disappearance rate in a flooded soil was lower than that in an
aerated soil which had a pH above 5. The solvent extractable carbofuran dis-
appearance rate constants for the field were in the range of 5.9 x 10-3 to
2.2 x 10-2 day-1 (Table B46) with an average of (1.6 ± 1.4) x 10-2 day-1
corresponding to half lives 31 to 117 days with an average of 68 ± 42 days.
The average mineralization rate constant for 14C-labeled carbofuran (Getzin,
1973) was 1.3 x 10-3 day-1 (Table B47), corresponding to a half life of
535 days. Carbofuran phenol was the major metabolite found in soils.
Solvent extractable 14c-carbonyl labeled carbaryl disappearance rate con-
stants for soils held under aerobic conditions in the laboratory were 2.1 x
10"2 to 7.3 x 10-2 day-1 (Table B48) with an average of (3.7 ± 2.1) x 10_2
day-1 corresponding to half lives 9 to 34 days with an average of 22 ± 9 days
(Kazano et al., 1972). In the same report, mineralization rate constants were
9.5 x 10-4 to 1.4 x 10-2 day"1 with an average of (6.3 ± 6.4) x 10" 3 day-1
corresponding to half lives 51 to 728 days with an average of 309 ± 284 days.
The mineralization rate constants may not represent the total ring structure
breakdown, since the position of l^C was on the side chain. Solvent extract-
able carbaryl disappearance rate constants for the field were 2.8 x 10*2 to
1.9 x 10"! day-1 (Table B49) with an average of (10.0 ± 8.0) x 10*2 day-1
54
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corresponding to half lives 4 to 25 days with an average of 12 ± 11 days.
However, some of the data were derived using an analytical method which con-
verts carbaryl to arnaphthol prior to measurement (Johnson and Stansbury,
1965). Thus, this method would not be able to differentiate between the
a-naphthol already present as a result of metabolism and the a-naphthol de-
rived from the hydrolysis of carbaryl. One report indicated a 40-day lag
phase (Caro et al., 1974).
DDT, Aldrln, Dieldrin, Endrin, Chlordane, Heptachlor and Lindane—
DDT, aldrln, dieldrin, endrin, chlordane, heptachlor and lindane were
widely used chlorinated hydrocarbon Insecticides several years ago. This
group of Insecticides 1s generally very persistent 1n the environment, and
their half lives in soils are generally over one year.
DDT 1s the representative chemical of the chlorinated hydrocarbon Insec-
ticides. Two major metabolites of DDT are ODD (1,1-dichloro-2,2-b1s(p-
chlorophenyl)ethane) and DDE (1,1-d1chloro-2»2-bis(p-chloropheny1Methylene).
DDD and DDE are as toxic and persistent as the parent chemical DDT. There-
fore, the solvent extractable parent chemical disappearance rates reflect the.
combined disappearance of:DDEi DDD and DDT. Solvent extractable DDT dis-
appearance rate : constants w^re- in .the range of.'1.2. x 10-4 to 6.5 x 10-3 day-1
(Table B50) with an average of (1.3 ± 1.7 J x 10-4 day-1 corresponding to half
lives 106 to 5,675 days with ah average of,1,657 ± 1,629 days. Under anaero-
bic conditions, DDT disappeared rapidly fnxn soils while the concentration of
metabolites Increased. The DDT disappearance rate increased as the incuba-
tion temperature Increased (Guenzi and Beard, 1976). Solvent extractable DDT
disappearance rate constants.for anaerobic soils at temperatures below 40°C
were 3.6 x lO"4 to 7.3 x 10"3 day"' (Table 851) with an average of (3.5 ± 2.9)
x 10"3 day-' corresponding to an average half life of 692 ± 854 days. Bound
residues (up to 341 of total 14c-activity)\were formed 1n 14C-DDT treated
soils under aerobic and anaerobic Incubation (Guenzi and Beard, 1976;
Lichtenstein et al., 1977).
Degradation rates In soils for aldrln and.dieldMn were reported to-
gether, since their physlochemical characteristics are similar. The solvent
extractable aldrin and dieldrin disappearance rate constants for the field
cases were 7.0 x 10-5 to 9.6 x 10" 3 day-1 (Table 852) with an average of
(2.3 ± 2.3) x 10-3 day-1 corresponding to an average half life of 1,237 ±
2,454 days. The solvent extractable a.ldr1n and dieldrin disappearance rate
constants for soils under laboratory aerobic incubation conditions reported
by Lichtenstein et al. (1977) and Lichtenstein and Schulz (1959) appeared to
be higher than that from the field soils, 1.3 x 10"2 (Table B53) vs 2.3 x 10-3
day-1.
According to one report (Guenzi et al., 1971), solvent extractable endrin
disappearance rate constants for fields under flooded or nonflooded conditions
were 5.3 x 10-3 and 1.5 x 10^3 day-1 (Table B54) corresponding to half lives
130 and 468 days, respectively. The average solvent extractable endrin dis-
appearance rate constant 1n flooded soils under laboratory studies was (3.0 ±
1.6) x 10-2 (Table B55), corresponding to an average half life of 31 i 19
days.
55
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The average half life for chlordane (a and y isomers) in the field was
about the same as that for aldrin and.dieldrin, (1,214 ± 2,453 days) and sol-
vent extractable chlordane disappearance rate constants were in the range
of 6.9 x TO-5 to-8.0 x'10-2 day-i (Table B56) with an-average of (2.4 ± 2.5)
x 10-3 day-1.
Solvent extractable heptachlor disappearance rate constants for field
•cases'were 7.8 x 10-3 to 1.4 x 10:2 day-' (Table B57) with an average of
(4.6 + 5.5) x 10_3 day-1 corresponding to an average half life of 426 ±
352 days. The average half life for heptachlor in soils incubated aerobical-
ly in the laboratory was 63 days (Table B58) (Lichtenstein and Schutz, 1959).
Solvent extractable lindane disappearance rate constants for field cases
were in the range of 6.0 x 10"4 to 7.9 x 10-3 day-1 (Table B59) with an
average of (2.4 ± 1.9) x 10-3 day-1 corresponding to half lives 88 to 1,146
days with an average of 450 ± 280 days. Solvent extractable lindane dis-
appearance rate constants for soils under laboratory aerobic and flooded con-
ditions (Mathur and Saha, 1977) were 2.6 x 10-3 (Table B60) and 4.6 x 10-3
.day-1 (Table B61) corresponding to half lives of 276 and 174 days,..respec-
tively.
Fungicides
PCP and Captan—
PCP (pehtachlorophenol) is used as a wood preservative, and until a few
years ago, it was a major herbicide used in rice paddy fields. PCP dis-
appears in soils and water by chemical, microbiological and photochemical
processes. Numerous soil fungi and bacteria degrade PCP, and numerous chlori-
nated phenols from mono- to tetra-chlorinated phenols were detected in PCP
treated soils (Kaufman, 1976, 1978). Microbial degradation appeared to be the
most important factor for the disappearance of PCP from soils. No degradation
was found in sterile soil (Watanabe, 1978). Solvent extractable PCP dis-
appearance rate constants for flooded soils were much higher than those for
aerobic soils. Solvent extractable PCP disappearance rate constants for
flooded soils were in the range of 1.1 x 10-2 to 1.2 x 10"! day1 (Table B62)
with an average of (7.0 ± 3.1) x 10"2 day-1, corresponding to half lives 6 to
64 days with anaverage of 15 ±15 days. Whereas, the solvent extractable
PCP disappearance rate constant under aerobic conditions, according to one
report. (Kauwatsuka and Igarashi, 1975), was 7.1 x 10-3 to 3.9 x 10-2 day-1
(Table B63) with an average of (2.0 ± 1.2) x 10*2 day-1 corresponding to half
lives 18 to 97 days with an average of 48 ± 29 days. The solvent extractable
PCP disappearance rate constant for a field case in one report (Watanabe,
1977) was higher than 5.0 x 10-2 day-1, corresponding to a half life of less
than 14 days.
Captan is a widely used chlorinated hydrocarbon fungicide. No reports
were found describing the use of chemical analyses for determining captan
residues in soils. However, the half lives of captan using bioassays appeared
to be no more than 3 days (Agnihotri, 1971; Griffith and Mattews, 1969).
56
-------
SUtMARY
A sunnary of the data presented In the Appendix (Tables Bl-863) 1s given
in Table 5-2. The k and T1/2 values computed using field data are based on
the disappearance of the parent compound (solverit-extractable). Rate coeffi-
cients and half-lives calculated on the basis of mineralization (IftCOg
evolution) as well as solvent-extractable parent compound disappearance under
laboratory conditions are also Included. Unless otherwise specified, the
laboratory studies were performed under aerobic conditions and Involved mea-
surement of T4C02 evolution from 14C-ring labeled compounds. The means
and coefficient of variation values for k and t|/2 are shown 1n Table 5-2.
In most cases, the half-11 ves of pesticides under fteltl conditions are much
lower than under laboratory conditions;. Tfrfs can be attributed to the fact
that under field conditions a multitude of factors and processes contribute
to the disappearance of the pesticide, while laboratory studies are. generally
designed to be conducted under controlled conditions. Coefficient of varia-
tion (S CV) values in; Table 5-2 are less than 10(K, In a majority of the cases.
Considering the range 1 n soil and environmental conditions urider which degra-
dation was measured* the CV 1s rather small. Thus, the degradation rate carr
be. estimated within a factor of 2*4 for mostpesticides using data presently
available.
The data presented in Table. 5?3 consists of; only tj/2 values from
laboratory (aerobic) studies rather than f1«1d data for the following reasons:
(1) greater analytic reliability because of GC or '^C-assay, and (11) ti/z
values from laboratory studies are generally smaller and provide more conserv-
ative estimates than field data. As shown 1n Table 5-3, most chlorinated
hydrocarbons are grouped as persistent, while carboxyalkanolc acid herbicides
are nonperslstent. s-tr1az1nes, substituted ureas, and carbamate pesticides
are grouped as the moderately persistent compounds.
The half-Hves of pesticides in Soils varied over a wide range from less
than a few dsys to more than a year (basedon the sol vent extractable parent
chemical disappearance rates under aerobic, conditions). Pesticides were
placed into three groups based on their half-lives in soils (Table 5-3):
non-persistent (ti/2 < 20 days), moderately persistent (20 < ti/2 < 100
days) and persistent Ttj/2 > 100 days). Pesticides 1n the "First group
(non-persistent) are readily biodegradable. Microbial degradation 1s the
main factor in the disappearance of these chemicals 1n soils. Chemical
degradation, photodecomposltion and volatilization may contribute to the
disappearance of these pesticides, but they are believed to be minor
factors. Chemicals which fall into this group are 2,4-0, 2,4,5-T, dlcamba,
dalapon, methyl parathlon, malathlon, and captan. Microorganisms may be
Involved In the degradation of the second group (moderately persistent) of
pesticides, since degradation rates in sterile soils were generally Tower
than those in non-sterile soils. However, soil microorganisms that
extensively degrade these chemicals to C02, 'Hjp, and simple inorganic
salts could not be isolated. It appears ttoat microbial degradation of these
compounds Is due to cometaibolism. Chemical degradation, photodecomposltion,
evaporation and binding may also play key roles in the. disappearance of these
chemicals from soils, furthermore, significantamounts of metabolites may
accumulate in soils because of microbial cooetabollsBU chemical degradation
57
-------
Table 5-2. Degradation Rate Coefficients and Half-Lives for Several Pesti-
cides under Laboratory and Field Conditions.
Rate Coeff. (day-1) Half-Life (days)
Pesticide Mean %CV Mean SCV
A. HERBICIDES
2,4-D
Lab.*
0.066
74.2
16
56.25
Lab.
0.051
23.5
15
33.3
Field
3.6
83.3
5
100.0
2,4,5-T
Lab.
0.029
51.7
33
66.7
Lab.*
0.035
82.9
16
68.8
ATRAZ1NE
Lab.*
0.019
47.4
48
68.8
Lab.
0.0001
70.4
6900
71.5
Field
0.042
33.3
20
50.0
SIMAZTNE
Lab.*
0.014
71.4
75
73.3
Field
0.022
95.5
64
93.8
TRIFLURALIN
Lab.*
0.008
65,5
132
82.6
Lab.* (anaerobic) 0.025
-
28
-
Lab. (chain)
0.0013
-
544
-
Field
0.02
65.0
46
41.3
BROMACIL
Lab.*
0.0077
49.4
106
42.5
Lab.
0.0024
116.2
901
116.2
Field
0.0038
100.0
349
76.8
TERBACIL
Lab.*
0.015
33.3
50
' 26.0
Lab.
0.0045
124.0
679
124.5
Field
0.006
55.0
175
88.6
LINURON
Lab.*
0.0096
19.8
75
18.7
Field
0.0034
41.2
230
29.3
DIURON
Lab.
•
Field
0.0031
58.1
328
64.6
DICAMBA
Lab.*
0.022
80.2
14
85.7
Lab. (ring)
0.0022
-
309
Lab. (chain)
0.0044
-
147
-
Field
0.093
16.1
8
12.5
(Continued)
58
-------
Table 5-2. (Continued)
Rate Coeff. (day1) Half-Life (days)
Pesticide Rean lev Mian icv
PICLORAM
Lab.*
0.0073
58.9
138
67.4
Lab.
0.0008
111.3
8600
184.2
Field
0.033
51.5
31
77.4
DALAPON
Lab.*
0.047
-
15
-
TCA
Lab.*
0.059
103.4
46
119.6
Field
0.073
-
22
-
GLYPHOSATE
Lab.*
0.1
121.0
38
139.5
Lab.
0*0086
93.0
903
191.8
PARAQUAT
Lab.*
0.0016
•
487
Field
0.00015
-
4747
-
B. INSECTICIDES
PARATHION
Lab..*
0.029
48.3
35
82.9
Field
0.057
101.8
18
44.4
METHYL PARATHION
Lab,*
0.16
4
Field
0.046
-
15
-
DIAZINQN
Lab*
0.023
108.7
48
62.5
Lab.
0.022
-
32
. -
F0N0F0S
Lab.*
0.012
-r
60
MALATHION
Lab.*
1.4
71.4
0.8
87.5
PHORATE
Lab.*
0.0084
82
Field
0.01
30.0
7.5
24.0
CARBOFURAN
Lab.*
0.047
87.2
37
94.6
Lab.
0.0013
-
535
•
Lab.*
(anaerobic) 0.026
50.0
44
95.4
Field
0.016
87.5
68
61.8
(Continued)
59
-------
Table 5-2. (Continued)
Rate Coeff.
. -(day-1)
Half-Life (dayi.
Pesticide
Mean
%CV
Mean
;.CV
CARBARYL
Lab.*
Lab. (chain)
Field
0.037
0.0063
0.10
56.8
101.6
79.2
22
309
12
40.9
91.9
91.7
DDT
Lab.*
Lab.* (anaerobic)
0.00013
0.0035
130.8
82.9
1657
692
98.3
123.4
ALDRIN and
DIELDRIN
Lab.*
Field
0.013
0.0023
100.0
53
1237
198.4
ENDRIN
Lab.* (anaerobic)
Field (aerobic)
Field (anaerobic)
0.03
0.0015
0.0053
53.3
31
460
130
61.3
CHLORDANE
Field.
0.0024
104.2
1214
202.1
HEPTACHLOR
Lab.*
Field
0.011
0.0046
119.6
63
426
82.6
LINDANE
Lab.*
Lab. (anaerobic)
0.0026
0.0046
-
266
151
-
C. FUNGICIDES
PCP
Lab.*
Lab. (anaerobic)
Field
0.02
0.07
0.05
60.0
44.3
48
15
14
60.4
100.0
CAPTAN
Field
0.231
3
_
~These rates are based on the disappearance of solvent-extractable parent
compound under aerobic incubation conditions, unless stated otherwise.
60
-------
Table 5-3. Grouping of Pesticides Based on Their Persistence* in Soils under
Laboratory Incubation Conditions.
NON-PERSISTENT
ti/2 < 20 days
MODERATELY PERSISTENT
20 < ty2 £ 1°° toys
PERSISTENT
t|/2 > 100 days
2,4-D
2.4.5-T
Dicamba
Dalapon
Methyl Parathion
Malathion
Captan
Atrazioe
Simazine
Terbacil
Linuron
T.CA.
GTyphosate
Parathion
Diazinon
Fonofos
Phorate
Carbofuran
Carbaryl
Aldrin
Oieldria
Endrin
Heptachlor
PCP
Trlfluralin
Bromaci1
Picloram
Paraquat
cor
Chiordane
Lindane
^Persistence as determined by the rate of disappearance of the solvent-
extractable parent compound under aerobic laboratory incubation conditions.
61
-------
and photodeconposition. Unlike the first group of pesticides, solvent
extractable parent chemical disappearance rates are generally much highar
than mineralization rates. Mineralization rates 1n soils for the third group
(persistent pesticides) are nearly zero, and there are generally no clear
differences between solvent-extractable parent-chemical disappearance rates
in sterile and non-sterile soils. Most of the chlorinated hydrocarbon
insecticides belong to this group.
Even though a large number of literature citations describing the soil-
mediated degradation of pesticides were reviewed, efforts failed to establish
multiple regression equations which correlated degradation rates with soil
properties. Part of the problem arises in that many reports fail to give
soil physlochemical characteristics, incubation temperature and moisture
tension. Soil organic matter content, moisture tension, and temperature
appear to be important factors in the degradation of pesticides. These
factors are also related to microbial activity.
REFERENCES FOR SECTION 5
Agnihotri, V. P. 1971. Persistence of captan and Its effects on microflora,
respiration, and nitrification of a forest nursery soil. Can. J.
Microbiol. 17:377-383.
Alton, J. D. and J. F. Stritzke. 1973. Degradation of dicamba, picloram,
and four phenoxy herbicides in soils. Weed Sci. 21:556-560.
Baldwin, B. C., M. G. Bray, and M. J. Curl. 1966. The microbial decomposi-
tion of paraquat. Biochem. J. 101:15.
Beynon, K. I., G. Stoydin, and A. N. Wright. 1972. A comparison of the
breakdown of the triazlne herbicides cyanazine, atrazine and simazine in
soils and in maize. Pest. Biochen. Physiol. 2:153-161.
Bovey, R. W., C. C. Bowler, and M. G. Merkle. 1969. The persistence and
movement of picloram In Texas and Puerto R1can soils. Pest. Monitoring
J. 3:177-181.
Bro-Rasmussen, F., E. Noddegard, and K. Yoldum-Clousen. 1968. Degradation of
diazinon in soil. J. Sc1. Food Agr. 19:278-281.
Burge, W. D. 1971. Anaerobic decomposition of DDT in soil. Acceleration by
volatile components of alfalfa. J. Agr. Food Chem. 19:375-378.
Burns, R. G. and L. J. Audus. 1970. Distribution and breakdown of paraquat
in soil. Weed Res. 10:49-58.
Caro, J. H., H. P. Freeman, D. E. Glottelty, B. C. Turner, and W. M. Edwards.
1973. Dissipation of soil incorporated carbofuran in the field. J.
Agr. Food Chem. 21:1010-1015.
62
-------
Caro, J. H.» H. P. Freeman, and B. C. Turner. 1974. Persistence 1n soil and
losses in runoff of sol1-Incorporated carbaryl In a small watershed.
J. Agr. Food Cherc. 22:860-863.
Clay, D. V. 1973. The persistence and penetration of large doses of simazine
In uncropped soil. Weed Res. 13:42-50.
CHath, M. M. and W. F. Spencer. 1971. Movement and persistence of dleldrln
and lindane In soil as Influenced by placement and Irrigation.. Soil Sc1.
Soc. Amer. Proc. 35:791t795.
Crosby, D. 6. 1973. The fate of pesticides 1n the environment. Ann. Rev.
Plant Physiol. 24:467-492.
Duseja, D. R. and E. E. Holmes. T978. Field persistence and movement of
trlfluralln 1n two soil types. Soil Sc1. 125:41-48.
Edwards, C. A. 1972. In_Organic Chemicals In the Soil Environment, eds.
Goring, C. A..I., and J. W. Hamaker, Vol. 2, pp. 515-568. Marcel Dekker,
New York.
Foster, R. K. and R. B. McKercher. 1973. Laboratory Incubation studies of
chlorophenoxyacetlc acids in chernozemlc soils. Soil Biol. Blochem.
5:333-337.
Fryer, J. D., R. J. Hance and J. W. Ludwlg. 1975. Long-term persistence of
paraquat 1n a sandy Toam sail. Weed Res. 15:189-194.
Gardiner, J. A., R. G. Rhodes, J. B. Adams, Jr., and E. J. Soboczenskl. 1969.
Synthesis and studies with 2-14c-labeled bromacll and terbacll. J. Agr.
Food Chem. 17:980-986.
Getzln, L. W. 1967. Metabolism of dlazlnon.and zinophos 1n soils. J. Econ.
Entomol. 60:505-508.
Getzln, L. U. 1968. Persistence of dlaz.lnon and zinophos In soil: Effects
of autoelaving, temperature, moisture, and activity. J. Econ. Entomol.
61:1560-1565.
Getzln, L. W. 1973. Persistence and degradation of carbofuran 1n soil.
Environ. Entomol. 2:461-467.
Getzin, L. W. and R. K. Chapman. 1960. The fate of phorate in soils. J. Econ.
Entomol. 53:47-51.
Getzln, L. W. and C. H. Shark, Jr. 1970. Persistence, degradation, and
b1oact1v1ty of phorate and Its oxidative analogues 1n soil. J. Econ.
Entomol. 63:52-58.
Gibson., W. P. and R. G. Bums. 1977. The.breakdown of mala.thlon in. soil and
soil components. Microbial Ecol. 3:2T9-230
63
-------
Glass, B. L. 1972. Relation between the degradation of DDT and the iron
redox system in soils. J. Agr. Food Chem. 20:324-327.
Goring* C. A. I. and J. W. Hamaker. 1971 - The degradation and movement of
picloram in soil and water. "Down to Earth 27(1):12-15.
Goswami, K. P. and R. E. Green. 1971. Microbial degradation of the herbicide
atrazine and its 2-hydroxy analog in submerged soils. Environ. Sci.
Techno!. 5:426-429.
Gowa,. T. K. S. and N. Sethunathan. 1976. Persistence of endrin in Indian
rice soils under flooded conditions. J. Agr. Food Chem. 24:750-753.
Gowa, T. K. S. and N. Sethunathan. 1977. Endrin decomposition in soils as
influenced by aerobic and anaerobic conditions. Soil Sci. 125:5-9.
Green, R. E., K. P. Goswami, M. Mukhtar, and H. Y. Young. 1977. Herbicide
from cropped watersheds in stream and estuarine sediment in Hawaii.
J. Environ.. Quality 6:145-154.
Griffith, R. L. and S. Matthews. 1969. The persistence in soil of the
fungicidal seed dressings captan and thiram. Ann. Appl. Biol. 64:113-
118.
Guenzi, W; 0. and W. E. Beard. 1976. Picloram degradation in soils as
influenced" by soil water 'content and-temperature. J. Environ. Quality
5:189-192.
Guenzi, W. D. and W. E. Beard. 1976. DDT degradation in flooded soil on
related to temperature. J. Environ. Quality 5:391-394.
Guenzi, W. D., W. E. Beard, and F. G. Viets, Jr. 1971. Influence of soil
treatment on persistence of six chlorinated hydrocarbon insecticides in
the field. Soil Sci.'Soc.-Amer. Proc. 35:910-91
Hall, J. K. and N. L. Hartwig. 1978. Atrazine mobility in two soils under
conventional tillage. J. Environ. Quality 7:63-68.
Hamaker, J. W. 1972. Decomposition: Quantitative aspects. Di Organic
Chemicals in the Environment, eds. Goring, C. A. ¦¦and J-. W. Hamaker
Marcel Dekker, New York.
Hance, R. J. 1969. Further observations of the decomposition of herbicides
in soil. J. Sci. Food Agr. 20:144-145.
Hance, R. J. 1974. Soil organic matter and the adsorption and decomposition
of the herbicide atrazine and linuron. Soil Biol. Biochem. 6:39-42.
Harris, C. R. and W. W. Sums. 1975. Persistence of velsicol HCS-3260
(AG-chlordane) in mineral and organic soil. Proc. Entomol. Soc.
Ontario 106:34-38.
64
-------
Helling, C. S., P. C. Kearney, and W. Alexander. 1971. Behavior of pestir
cides 1n soils. Adv. Agron. 23:14?-240.
Hill, G. D., J. W. McGahen, H. M. Baker, 0. W. Finnerty, and C. W. Bingeman.
1955. The fate of substituted urea herbicides In agricultural soils.
Agron. J. 47:93-104.
Howard, P. H., J. Saxena, P. R. Ourkins, and L.-T. Ou. 1975. Review and
evaluation of available techniques for determining persistence and
routes of degradation of chemical substances 1n the environment.
USEPA.
Joshi, 0. P. and N. P. Datta. 1975. Persistence and movement of simazine
in soil. J. Indian Soc; Soil Set. 23;263-265.
Johnson, D. P. and H. A. Stansbury. 1955. Adaptation of sevln Insecticide
(carbaryl) residue method to various crops. J. Agr. Food.Chemv
13:235-238.
Katsn, J. , T. W. ruhremann, and- E; Pv lichterrsteln. T-976. Binding of
[l$C] parathion in soil: A reassessment by pesticide persistence.
Science 193:891.-894.
Kaufman, D. D. 1976. Phenols. In herbicides, pp. 665-707, eds. Kearney,
P. C, and D. D. Kaufman. Marcel Dekker, Inc., New York.
Kauffitan, D. D. 1976." Soil degradation and persistence pf benchmark pesti-
cides. In A Literature Survey of Benchmark Pesticides, pp. 19-71.
USEPA. "*"
Kaufman, D. 0. 1978. Degradation of pentachlorophenol in soil, and by
soil microorganisms. l£ Pentachlorophenol, pp. 27-39, ed. Rao, K. R.,
Plenum Press, Hew York.
Kauwatsuka, S. and M. Igarashi. 1975. Degradation of PCP In soils, II.
The relationship between tha degradation of PCP and the properties of
soils, and the identification of the degradation products of PCP.
Soil Sci. Plant Nutr. 21:405-411.
Kazano, H., P. C. Kearney, and D. D. Kaufman. 1972. Metabolism of methyl-
carbamate insecticides in soils. J. Agr. Food Chem. 20:975-979.
Kearney, P. C. and C. S. Helling. 1969. Reactions of pesticides 1n soils.
Residue Rev. 25:25-44.
Kearney, P. C., J. R. Plimmer, W. B. Wheeler, and A. Konston. 1976. Per-
sistence and metabolism of dinitroaniltne herbicides in soils. Pest.
Biochem. Physiol. 6:229-238.
Khan, S. U. 1977. Determination of terbaclt: in soil by gas-liquid chroma-
tography with 63141 electron capture detection- :Bui1. Environ. Contamin.
Toxicol. 18:83-88.
65
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Khan, S. U. and P. B. Marriage. 1977. Residues of atrazine and its metabo-
lites in an ochard soil and their uptake by oat plants. J. Agr. Food
Chem. 25:1408-1414.
Khan, S. U., P. B. Marriage and W. J. Saidak. 1976. Persistence and move-
ment of diuron and 3,4-dichloroaniline in an orchard soil. Weed Sci.
24:553-586..
Kiigemgi, U. and L. C. Terriere. 1971. The persistence of zinophos and
dyfonate in soil. Bull. Environ. Contamin. Toxicol. 6:355-361.
Kishk, F. M., T. El-Essawi, S. Abdel-Ghafar, and M. B. Abou-Donia. 1976.
Hydrolysis of methyl parathion in soils. J. Agr. Food Chem. 24:305-307.
Konrad, J. 6., G. Chester, and D. E. Armstrong. 1969. Soil degradation of
malathion, a phosphorodithioate insecticide. Soil Sci. Soc. Amer. Soc.
33:259-262.
Kuhr, R. J., A'. C. Davis, and J. B. Bourke. 1974. Dissipation of guthion,
sevin; polyram, phygon and systox from apple orchard soil. Bull.
Environ. Contamin. Toxicol.' 11:224-230.
Laanio, T. L., G. Dupuis, and H. 0. Esser. 1972. Fate of 14C-labeled
diazinon in rice, paddy soil, and pea plants. J. Agr. Food Chem.
20:1213-1219.
Lafleur, K. S., W. R. McCaskill, and G. T. Gale, Jr. 1978. Trifluralin .
persistence in Cangaree soil. Soil Sci. 126:285-289.
Lavegila, J. and P. A. Dahm. 1977. Degradation of organophosphorus and
carbamate insecticides in the soil and by microorganisms. Ann. Rev.
Entomol. 22:483-513.
Leistru, M., J. H. Smelt, and R. Zandvoort. 1975. Persistence and mobility
of bromacil in orchard soils. Weed Res. 15:243-247.
Liechtenstein, E. P., L. J. DePew, E. L. Eshbaugh, and J. P. Sleesman. 1960.
Persistence of DDT, aldrin, and lindane in some midwestern soils. J.
Econ. Entomol. 53:136-142.
Lichtenstein, E*. P., T. W. Fuhremann, and K. R.'Schulz. 1971. Persistence
and vertical distribution of DDT, lindane, and aldrin residues 10 and
15 years after a single soil application. J. Agr. Food Chem. 19:
718-721.
Lichtenstein, E. P., J. Katan, and B. N. Anderegg. 1977. Binding of "per-
sistent" and "nonpersistent" ^C-labeled insecticides in an agricultural
soil. J. Agr. Food Chem. 25:43-47.
Lichtenstein, E. P. and K. R. Schulz. 1959. Breakdown of lindane and
aldrin in soils. J. Econ. Entomol. 52:118-124.
66
-------
Llchtensteln, E. P. and K. R. Schulz. 1959. Persistence of some chlorinated
hydrocarbon Insecticides as Influenced by soil types, rate of applica-
tion, and temperature. J. Econ. Entomol. 52:124-131.
Llchtensteln, E. P. and K. P. Schulz. 1964. The effects of moisture and
microorganisms on the persistence and metabolism of some organophos-
phorus Insecticides 1n soils, with special emphasis on parathion. J.
Econ. Entomol. 57:618-627.
Llchtensteln, E. P., K, R. Schluz. T. W. Futoremann, and T. T. Liaing. 1970.
Degradation of aldrln and heptachlor 1n field soils during a 10 year
period, translocation Into crops. J. Agr. Food Chem. 18:100-106.
Lutz, J. F., G»E. Byers, and T. J. Sheets. 1973. The persistence and
movement of plcloram and 2,4,5-T in sails. J. Environ.1 Quality 4:
485-488.
Marriage, P. B., W. J. Saidak, and F. G. Von Stryk. 1975. Residues of
atrazfne, slmazine, linuron, and diuron. after,repeated .annual applica-
tions 1n a peach orchard. Weed Res. I5:373-379.
Mathur, S. P., N. A. Hamilton., R. Greenhalgft, X. A. Macml 1 lan, and S. U.
Khan. 1976. Effect of microorganisms antf pers-istence of field-
applied carbofuran and dyfonate 1n a humlc melsol. Can. J. Soil Sci.
56:89-96.
Mathur, S. P. and J. G. Saha. 1977. Degradation of Hndane-14c in a
mineral soil and in an organic soil. Bull. Environ. Contamln. Toxicol.
17:424-430.
Matsumura, F. 1974. In Survival in Toxic Environments, eds. Khan, M. A. Q.
and 0. P. Bederka, Jr., pp. 129-154. Academic Press, New York.
McGrath, D. 1976. Factors ttiat influence the persistence of TCA in soil
Weed Res. 16:131-137.
Meikle, R. W., E. A. Williams,, and C. T. Redeman. 1966. Metabolism of
tordon herbic1de (4-am1no-3,5,6-tr1chloropicolinic acidJ in cotton
and decomposition in soil. J. Agr. Food Chem. 14:384-387.
Meikle, R. W., C. R. Youngson, R. T." Hedlund, ,'C. A. 'I, Goring^.J. W*.Hamaker,
and W. W. Addington.. 1973. Measurement and prediction of picloram
disappearance rates from soil. Weed Sci. 21:549-555.
Menzer, R. E., E. L. Fontanllla, and L. P. Ditman. T970. Degradation of
disulfoton and phorate 1n soil influence by environmental factors and
soil type. Bull. Environ. Contamln.. Toxicol. 5:1-5.
Menges, R. M. and S. Tamez. 1974. Movement and persistence of bensulide
and trifluralin in irrigated soil. Weed Sci- 22:67-71.
67
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Merkle, M. G., R. W. Bovey, and F. S. Davis. 1976. Factors affecting the
persistence of picloram in soil. Agron. J. 59:413-415.
Messersmith, C. G., 0. C. Burnside, and T. L. Lavy. 1971. Biological and
non-biological dissipation of trifluralin from soil. Weed Sci. 19:
288-290.
Miller, C. H., T. J. Monaco, and T. J. Sheet. 1976. Studies of nitralin
residues in soils. Weed Sci. 24:288-291.
Mingelgrin, U. and B. Yaron. 1974. The effect of calcium salts on the
degradation of parathion in sand and soil. Soil Sci. Soc. Amer. Proc.
-38:914-917.
Moshier, L. T. and D. Penner. 1978. Factor influencing microbial degrada-
tion of in soil. Weed Sci. 26:686-691.
Moyer, J. R., R. J. Hance, and C. E. McKone. 1972. The effect of adsorption
of adsorbents on the rate of degradation of herbicides incubated with
soil. Soil. Biol. Biochem. 4:307-311.
Munnecke, 0. M. and D. P. H. Hsieh. 1974. Microbial decontamination of
parathion and p-nitrophenol in aqueous media. Appl. Microbiol'. 28:
212-217.
Namdeo, K. N. 1972. Persistence of dalapon in grassland soil. Plant Soil
31:445-448.
Nash, R. G. and E. A. Woolson.. 1967. Persistence of chlorinated hydro-
carbon insecticides in soils. Science 157:924-927.
Normura, N. S. and H. W. Hilton. 1977. The adsorption and degradation of
glyphosate in five Hawaiian sugar cane soils. Weed Res. 17:113-121.
Obien, S. R. and R. E. Green. 1969. Degradation of atrazine in four
Hawaiian soils. Weed Sci. 17:509-514.
Ou, L.-T., J. M. Davidson, and D. F. Rothwell. 1978. Response of soil
microflora to high 2,4-D applications. Soil Biol. Biochem. 10:443-445.
Ou, L.-T., D. F. Rothwell, W. B. Wheeler, and J. M. Davidson. 1978. The
effect of high 2,4-D concentrations on degradation and carbon dioxide
evolution in soils. J. Environ. Quality 7:241-246.
Ou, L.-T. and H. C. Sikka. 1977." Extensive degradation of silvex by syner-
gistic action of aquatic microorganisms. J. Agr. Food Chem. 25:
1336-1339.
Parr, J. F. and S. Smith. 1973. Degradation of trifluralin under laboratory
conditions and soil anaerobiosis. Soil Sci. 115:55-63.
68
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Probst. G.^Wv, T. Golab, R. J. Herberg, F. J* Holzer, S. J. Parka, C. V. D.
Shans, and J. B. Tepe. 1967. Fate of trlfluralin in soils and plants.
J. Agr. Food Chem. 15:592-599.
Radosevlch, S. R. and W. L. Wlnterlin. 1977. Persistence of 2,4-D and
2,4,5-T in chaparral vegetation and soil. Weed Sci. 25:423-425.
Rajaram, K. P. and N. Sethunathan. 1975. Effect of organic sources as
the degradation of parathion in flooded diluvial soil. Soil Sci.
119:296-300.
Roadhouse, F. E. B. and L. A. Birk. 1961. Penetration of and persistence
in soil of the herbicide 2-chloro-4,6-bis(ethylaraino)-s-trazine
(simazine). Can. J. Plant Set. 41:252-259.
Rueppel, M. L., B. B. Brightwell, J. Schaefer, and J. T. Marvel. 1977.
Metabolism and degradation of glyphosate in soil and water. J. Agr.
Food Chem. 25:517-526.
Satfher, R. M. G., G. F. Ludvikv antl- Ji. M. Denting. 1971, Bioat'tivity and
persistence of some parathion formulations in soil. J. Econ. Entomol.
65:329-332.
Saltzman, S., U. Mingelgrln, and B. Yaron. 1976. Role of water in the
hydrolysis of parathion and methylparathion on kaolintte. 0. Agr.
Food Chem. 24:739-743.
Sanborn, J. R., B. M. Francis, and R. L. Hetcalf. 1976. The degradation of
selected pesticides 1n soil: A review of the published literature.
USEPA.
Savage, K. E. 1973. Nitralin and trlfluralin persistence in soil. Weed
Sci. 21:285-288,
Savage, K.E. and W. L. Barrentine. 1969. Trlfluralin persistence as
affected by depth of soil incorporation. Weed Sci. 17:349-352.
Schulz, K. R. and E. P. Lichtenstein. 1971. Field studies on the persis-
tence and movement of dyfonate in soil. J. Econ. Entomol. 64:283-287.
Scifres, D. J. and T. J. Allen. 1973. Dissipation of dicamba from grass-
land soils of Texas. Weed Sci. 21:393-396.
Sethunathan, N. 1973. Degradation of parathion in flooded acid soils.
J. Agr. Food Chem. 21:602-604.
Sethunathan, N. 1973. Microbial degradation of Insecticides in flooded
soil and in anaerobic cultures. Resi
-------
Sethunathan* N. and I. C. MacRae. 1969. Persistence and biodegradation of
diazlnon in submerged soils. 0. Agr. Food Chem. 17:221-225.
Sethunathan, N. and T. Yoshida. 1969. Fate of diazinon in submerged
soil accumulation-of hydrolysis product. J. Agr. Food Chem. 17:
1192-1195.
Sethunathan, N. and Y. Yoshida.- 1973. Parathion degradation in submerged
rice soils in the Philippines. J. Agr. Food Chem. 21:504-506.
Siddaramappa, N., K. P. Rajaram, and N. Sethunathan. 1973. Degradation of
parathion by bacteria isolated from flooded soil. Appl. Microbiol.
26:846-849.
Skipper, H. D. and V. V. Volk. 1972. Biological and chemical degradation
of atrazine in three Oregon soils. Weed Sci. 20:346-347.
Sikka, H. C. and D. E. Davis. 1966. Dissipation of atrazine from soil by
corn, sorghum and Johnson grass. Weeds. 14:289-293.
Strons, G. J., R. Frank and R. M. Dell. 1977. Picloram residues in sprayed
MacDonald-Cartier freeway right-of-way. Bull, Environ. Contamin.
Toxicol. 18:526-533.
Smith, A. E. 1972. Persistence of trifluralin in small field plots as
analysis by a rapid gas chromatographic method. J. Agr. Food Chem.
20:829-831.
Smith, A. E. 1973. Degradation of dicamba in prairie soils. Weed Res.
13:373-378.
Smith, A. E. 1974; Breakdown of the herbicide dicamba and its degradation
product 3,6-dichlorosalicyclic acid in prairie soils. J. Agr. Food
Chem. 22:601-605.
Smith, A. E. 1974. Degradation of trichloroacetic acid in Saskatchewan
soils. tSoil Biol. Biochem. 5:201-212.
Smith, A. E. and D. R. Cullimore. 1975. Microbiological degradation of the
herbicide dicamba in moist soils at different temperatures. Weed
Res. 15:59-63.
Smith, A. E. and G. S. Edmond. 1975. Persistence of linuron in Saskatchewan
soils. Can. J. Soil Sci. 55:145-148.
Smith, A. E. and A. Walker. 1977. A quantitative study of asulam persis-
tence in soil. Pest. Sci. 8:449-456.
Spencer, W. F., M. M. Cliath, D. R. Davis, R. C. Spear, and W. J. Pependorf.
1975. Persistence of parathion and its oxidation to paraoxon on the
soil surface as related to worker reentry into treated crops. Bull.
Environ. Contamin. Toxicol. 14:265-272.
70
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Sprankle, P., W. F. Meggitt, and 0.-Penner. 1975. Adsorption, mobility,
and microbial degradation of glyphosate in the soil. Weea Sci. 23:
229-234.
Stewart, D. K. R. and D. Chlsholm. 1971. Long-term persistence of BHC,
DDT, and chordane 1n a sandy loam soil. Can. J. Soil Sci. 51:379-383.
Stewart, D. K. R. and S. 0. Gaul. 1977. Persistence of 2,4-D and 2,4,5-T
and dlcamba in a Dykeland soil. Bull. Environ. Contamln. Toxicol.
18:210-218,
Suett, D. L. 1975. Persistence and degradation of chlorfenvinphos, chlo-
mephos, disulfoton, phorate and pir1m1phos-ethyl following spring and
late-sunner soil application. Pest. Sci. 6:385-393.
Suzuki, M., Y. Yamato, and T. Watanabe. 1977. Residue 1n soil, organo-
chlorine insecticide residues in field soils of the Kita Kyusha
dlstrict-rJapan 1970-74. Pest. Monitoring J. 11:88-93.
Tafurl, F., H. BusinelH, L. Scarponi, and C. Marucchini. 197-7'. Dieldrin
and movement .of AG Chlordane in soil and Its residue in alfalfa. J.
Agr. Food Chem. 25:353-358.
Talekar, N. S., L.-T. Sun, £.-M. Lee, and J.-S. Cheri. 1977. Persistence
of some, insecticides jn subtropical soil. J. ,Agr. FoodChera. 25:
348-352,
Tu, C. M. and VI. B. Bollen. 1968. Interaction between paraquat and microbes
in soils. Weed Res. 8:38-45.
Usorol, N. J. and R. 0. Hance. 1974. The effect of temperature and water
contents oh the rate of decomposition of the herbicide linuron. Weed
Sc1. 16:19-21.
Venkateswarlu, K., T. K. Siddarame Gowda, and -N. Sethunathan. 1977. Per-
sistence and blodegradation of carbofuran in flooded soil. J. Agr.
Food Chem. 25:533-53&.
Voerman, S. and A. F. H. Besemer. 1975. Persistence of dleldrln, lindane,
and DDT 1n a light sandy soil and their uptake by grass. Bull. Environ.
Contamin. Toxicol. 13:501-505.
Walker, A, 1974. A simulation model for prediction of herbicide persistence.
J. Environ. Quality 3:396-401.
Walker, A. 1976a. Simulation of herbicide persistence in soil. I. Sima-
zlne and prometryne. Pest. Sci. 7:41-49.
Walker. A. 1976b. Simulation of herbicide persistence in soil. II.
Simazine and linuron in long-term experiments. Pest. Sci. 7:50-58.
71
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Walker, A. 1978a. The degradation of methazole in soil. I. Effects of
soil type, soil temperature, and soil moisture content. Pest. Sci.
9:326-332.
Walker, A. 1978b. "Simulation of the persistence of eight soil-applied
herbicides. Weed Res. 18:305-313.
Walker, W. W. .1976. Chemical and microbiological degradation of malathion
and parathion in an estuarine environment. -J. Environ. Quality 5:
,210-215,
Walker, W. U: and B. J. Stojanovic. 1973. Microbial versus chemical
degradation of malathion in soi1. J. Environ. Quality 2:229-232.
Ware, G. W., B. Estesen, W. C. Kronland, and W. B. Cahill. 1977. DDT
volatilization from desert and cultivated soils. Bull. Environ.
Contamin. Toxicol. 17:317-322.
Watanabe,.I. 1977. Pentachlorophenol-decomposing and PCP-tolerant bacteria
in field soil, treated with PCP. Soil Biol. Biochem. 9:99-103.
Watanabe, I. 1978. Pentachlorophenol (PCP) decomposing activity of field
Soils treated annually with PCP. Soil Biol. Biochem. 10:71-75.
Wheeler, W.B., C. D. Stratton, R. R. Twilley, L.-T. Ou, D. A. Carlson, and
J. M. Davidson. 19.79. Trifluralin degradation and binding in soil.
J. Agr. Food Chem. 27:702-706.
Wilkinson, A. T. S. and D. G. Finlayson. 1964. Toxic residues in soil
9 years after treatment with aldrin and heptachlor. Science Feb. 14,
681-682.
Willis, G. H., J. F. Parr, S. Smith, and B. R. Carrol. 1972. Volatiliza-
tion of dildrin from fallow soil as affected by different soil water
regimes. J. Environ. Quality 1:193-196.
Wilson, .R. G., Jr. and H. H. Cheng. 1976-. Breakdown and movement of 2,4-D
in the soil under field conditions. Weed Sci. 24:461-466.
¦Wilson, R1. G.-,-0r. and H. H. Cheng. 1978. Fate of 2,4-D in a Naff silt
loam soil. J. Environ. Quality 7:281-286.
Wilson, D: M. and P. C. Olaffs. 1973. Persistence and movement of a- and
Y,- chlordane in soil following treatment with high purity chlordane
(velsical"HCS-3260). Can. J. Soil Sci. 53:465-472.
Wolf, D. C. and J. P. Partin. 1974. Microbial degradation of 2-carbon-
l^bromacil and terbacil. Soil Sci. Soc. Amer. Proc. 38:921-925.
Yaron, B. 1975. Chemical conversion of parathion on soil surfaces. Soil
Sci. Soc. Amer. Proc. 39:639-642.
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Yoshida, T. and T. P. Castro. 1975. Degradation of 2,4-0, 2,4,5-T, and
picloram 1n two Philippines soils. Soil Sci. Plant Nutr. 21:397-404.
Zlmdahl, R. L. and S. M. Gwynn. 1977. So.11 degradation of three dinitro-
anHlnes. Weed Sc4. 25:247-251.
Zlmdahl, R. L., V. H. Freed, H. L. Montgomery, and W. R. Furtlck. 1970.
The degvacation of trlazlne and uracil herbicides in soil. Weed Res.
10:16-26.
Ambrosi, D., P. C. Kearney, and J. A. Macchia. 1977. Persistence and meta-
bolism of phosalone 1n soil. Jour. Agrlc. Food Chen. 25:342-347.
Bartha, R. 1971. Fate of herbicide-derived chloroanilines in soil. Jour.
Agrlc. Food Chem. 19?385-387.
Chiska, H., and P. C. Kearney. 197€. Metabolism of propanil .in soil s.
Jour. Agrlc. Food Chen. 18:854-858.
Flashlnski, S. J., and E. P.' LichtenStein, 1974. Degradation of dybonate
in soil incubated with Rhz6pus arrhiius. Can. Jour. Hlcrob. 20:871-875.
Hsu., T. S., and R. Bartha. 1976. Hydrolyzable and non-hydroTyzable 3,4-
dlchloroanlline-humus complexes and their respective rates of blodegra-
dation. Jour. Agric. Food Chem. 24:118-122.
73
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SECTION 6
PARTITIONING OF INORGANIC PHOSPHATE IN SOIL-WATER SYSTEMS
V. E. Berkheiser, J. J. Street, P. S. C. Rao, and T. L. Yuan
Phosphorus has been implicated as a primary factor contributing to eu-
trophication of surface water supplies (0hle,1953; Mackenthun, 1965; Stewart
and Rohlick, 1967; Vollenweider, 1968; Lee, 1970). The contribution of soil-
applied phosphorus to runoff from watersheds in agricultural areas needs to
be. elucidated'/ A prerequisite to understanding the role of P-fertilizer in
runoff is an assessment of the interaction of phosphorus and soil constitu-
ents '('e.g. clay minerals, metal oxides, etc.). The nature of phosphorus-
soil reactions is complex, as evidenced by the large number of investigative
papers in the literature (Beckett and White, 1964; Ozanne and Shaw, 1967;
Kafkafi et al., 1967; Fox and Kamprath, 1970; Gunary, 1970). The complex na-
ture of P reactions with soils and soil constituents have been extensively
investigated and will be discussed in the following sections of this report.
Since soil 1s a dynamic chemical and biological system in a constant
state of flux and disequilibrium, interpretation of research in closed arti-
ficial systems should be made with caution. It is hoped that research con-
ducted by this group of investigators can add to the understandings thus far
established. The primary research objectives, to be elaborated on later, are
to quantitatively and qualitatively assess the processes responsible for
partitioning of inorganic phosphorus between the solution phase and the solid
phase of soils. The reaction of soluble phosphorus with soils must begin
with an assessment of the chemical forms of P involved, the nature of the
soil constituents, and the kinetics and reversibility of the reaction.
Soil phosphorus is generally divided into two broad categories: inor-
ganic- P,, that associated with the soil mineral particles; and organic P,
that which forms an integral part of the soil organic matter fraction. The
organic-P fraction, which may constitute 20 to 80 percent of the total soil
phosphorus, is inert in its org.anic form. It is only after mineralization
that it becomes involved in the chemical reactions discussed in this review.
The nature of P retention by soils has been postulated to include pre-
cipitation of discrete P minerals, surface adsorption on minerals, microbial
immobilization, plant uptake, and precipitation of mixed P solid phases (Hsu,
1954). The importance of any one or combination of these mechanisms is de-
pendent on a host of variables that is often difficult to evaluate. This
report will discuss some of the literature related to these processes involv-
ing soil phosphorus.
74
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During the past 10 to 15 years there has been a tremendous Increase 1n
the amount of research dealing with the chemistry of soil phosphorus. This
rapid growth In conjunction with the wide range, of disciplines conducting the
research has generated some confusing nomenclature with regard to the forms
of phosphorus occurring In soils. This confusion In terminology reflects the
complexity of soil phosphorus. The inorganic solT phosphorus forms generally
encountered in the literature include the following: soil solution Inorganic
phosphate, fertilizer phosphate* adsorbed phosphate (rapidly reacting), ad-
sorbed phosphate (slowly reacting), and discrete crystalline phosphates.
Other terminology that may be grouped under the aforementioned phases in-
clude: occluded P, non-occluded P, 1sotop1cally exchangeable P, resin-extrac-
table P, "sorbed P", precipitated P, exchangeable soil P, "surface phosphorus",
labile, and non-labile P.
The soil solution phase mediates a multitude of phosphorus transforma-
tion reactions in soils. The Inorganic phosphorus in the soil solution takes
part in many complex equilibria; some of these are within the liquid phase
only (homogeneous, equilibria) and others occur between the solid and aqueous
phase; (heterogeneous equi 1 Ibrta). The overall equilibrium, expressed as
psolid ^solution is heavily biased by the reaction to the left and soil
phosphorus can *be classified as "sparingly soluble."
Phosphorus 1n Soil Solution
Phosphorus occurs in nature; almost exclusively as. phosphatei the fully
oxidized state, with formal oxidation number V and coordination number 4.
Phosphate occurs 1n all knownminerals as orthophosphate, the Ionic form be-
ing represented as
3-
[6-1]
or as [POtJ3". The distribution of the several acid and base species of
orthophosphates in solution 1s governed by pM. Information on the pH-
dependent distribution of the different species is required 1n interpreting
the solubility behavior, complex formation and sorption processes of phos-
phorus in the soil-water system. Orthophosphorlc acid dissociates stepwise
1n aqueous systems releasing a total of three protons as pH increases.
0
ir
HO—P—OH [6-2]
1
I
0
H
Orthophosphorlc Acid
0
1
0--P-0
I
75
-------
log k°
H3P(V«-* H+ + H2PO4
H2P0; 4—» H+ + HPOfT
HPOg" < > H+ + P02r
-12.33
-2.12
-7.22
[6-3]
[6-4]
[6-5]
Thus it can be seen from equations 6-3 through 6-5 that a change in the pH
results in a subsequent change in the ratio of the different_orthophosphate
species. If the solution pH is 2.12 the ratio of H3P0il/H2P0^_is unity and
solution gH's of 7.22 and 12.33., respectively, result in H2P0^/HP0§" and
HP0£~/P03 ratios being unity. Thus in interpreting the chemistry of phos-
phorus in the soil-water system it is pertinent that notice be given to the
pH of the system. A plot showing the orthophosphate species as the logarithm
of the mole fraction of the total P in solution is given as a function of pH
in Figure 6-V. As can be readily seen from Figure 6-1, the H2PO4 and HP0£
ions are the predominanty species that can be expected to take part in phos-
phate; sorption reactions in the soil solution of most agricultural soils in
the pH range of 4.0 to 8.5.
The concentration of phosphorus in the soil solution is of the order of
1 to 0.1 pg P/ml. It varies with the properties of both the solid and the
aqueous phases of the soil and also with the solid/solution ratio. The cheir -
ical species of solution phosphorus are a function-of the reactions of proto-
nation and soluble complex ion formation. These species include H3POlt, H2P04,
HPO^", POrf, and the soluble complexes of these ions. The degree of complexa-
tion and the predominance of a particular phosphoric acid species can be cal-
culated from a knowledge of the pH, the complexing cation concentration, and
the cation-phosphate complex stability constant, and the ionic strength of the
medium (Sillen and Martell, 1964). The ionic species H2P0(;~ are the predomi-
nant phosphoric acid dissociation products in solution in most soils (pH range
4.0-8.5). Since the soil solution will contain several kinds of metallic
cations (i.e., Ca2+, Mg2+, K+, Fe3+, Al3+, etc.) capable of forming complexes
with H2P0^ and HP0^+, a part of the solution phosphorus will, exist as soluble
metallic-phosphate complexes (i.e., CaH2P0{, CaHP0°, FeH2P0$'f, etc.). In
some cases the degree of complexation of solution phosphorus may be a signi-
ficant part of the total soil solution phosphorus (Larsen, T965-, T966a; Weir
and Soper, 1963; Taylor and Gurney, 1962a). The chemical speciation of soil
solution phosphorus is an important part of the chemical reactions that govern
the distribution of soil applied P between the solution phase and the solid
phase.
Discrete Crystalline Phosphates
Based on the "Solubility Product" principle it has been postulated that
Fe, Al, and Ca may precipitate out soil solution phosphorus (Kittrick and
Jackson, 1957; Hemwell, 1957; Charkravarti and Talibudeen, 1962; Shipp and
Matelski, 1960). However, the general occurrence of discrete Fe and Al phos-
phates as factors controlling soluble P levels in soils seems doubtful on the
basis of ion product data presented by Bache (1964) and the experimental ob-
servations of Hsu (1964). It is not surprising to find conflicting published
76
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H3PQ4 H2PQ4*"
-2
-4
-6
- -Q
-10
6
4
a
10
PH
Figure 6-1. Inorganic orthophosphate speciation in aqMeou$ solutions as a function
of pH.
-------
research concerning the presence of discrete solid phase phosphorus compounds
based on the solubility product values published for "pure" well-defined
crystalline compounds. The lack of agreement between 'phosphorus.concentra-
tion in the soil solution and the solubility of a pure crystalline compound
does not exclude the presence, of such a compound. The problem of incongruent
dissolution and'complex formation, impurities, and degree of crystallinity
can all contribute to the disparity between calculated and observed solubility
products (Bjerrium, 1949; Greenwald, 1942; Ericsson, 1949; Taylor and Gurney,
1962a; Raupach, 1963).
The use of solubility diagrams to evaluate the upper limits of P soluble
in soils is a valid and useful aid in understanding phosphate reactions in
soils (Stumm and Morgan, 1970; Lindsay and Vlek, 1977; Griffin and Jurinak,
1974). The solubility diagram presented in Figure 6-2 was adapted from stumm
and Leckie (1971) and assumes a Ca2+ activity of 10~3M, F" activity controlled
by CaF2, and an Al3+ and Fe3+ activity controlled by A1(0H)3 and Fe(0H)3,
respectively. As evident in Figure 6-2, Al3+ and Fe3+ control P solubility
at low pH values and Ca2+ controls the P level under alkaline conditions. The
preceding discussion on discrete P minerals is- by no means conclusive and
there exist'many other possible P minerals. Sill en and Martell (1964) have
listed some relevant sparingly soluble phosphorus salts of magnesium, calcium,
¦aluminum, iron, and potassium, while Nriagu (1976) has recently evaluated
several geologically important phyochate minerals.
Although Hsu (1976) discussed the terms precipitation and adsorption, it
is difficult to distinguish between the initial reaction of precipitation and
adsorption. As a result, these two phenomenon are often grouped together as
"sorption." There is probably a continuum in terms of reaction rates between
the various adsorbed and crystalline phosphates. Thus, their distinction on
a kinetic basis is difficult (Larsen, 1967) and must be largely arbitrary ex-
cept under special conditions such as "microsites" around fertilizer granules.
The presence of discrete solid phases is probably a more important mech-
anism for controlling soluble P levels in the vicinity of phosphate fertilizer
particles than in the bulk soil. The presence of Fe and A1 phosphates has
been reported as temporary soil-fertilizer reaction products around fertiliz-
er granules (Lindsay and Stephenson, 1959; Huffman, 1969). The presence of
discrete phosphorus solid phases, whether'around a fertilizer particle or on
the surface of a P-enriched site of some other mineral, is a feasible and
likely mechanism for P retention in soil.
It has been postulated that phosphate adsorption (chemical) and precipi-
tation are basically the same mechanism, both being a fundemently attrac-
tion between A1 (or Fe) and phosphate (Mattson et al., 1951; Kittrick and
Jackson, 1957; Hsu and Rennie, 1962). Hsu (1964) has suggested that phosphate
adsorption is a special case of precipitation in which Al or Fe remains as the
constituent atom of the corresponding metal hydroxide or oxide; however, he
also elaborates on the practical point that conceptually there are some basic
differences in the two processes.
78
-------
Because of the large volume of literature and apparent contradictory
evaluation of the magnitude of phosphate sorptlon-desorption by soils, an
attempt was made here to determine a universal partition function from the
literature data. Phosphorus sorptlon-desorption and transformations in the
current version of the Agricultural Runoff Management (ARM) model (Donigan et
al., 1977} can be depicted as follows:
This model assumes that all reaction rates are first-order in phosphate con-
centration In the corresponding phases and that the forms of phosphate can be
described as shown above. The present discussion is restricted to the rela-
tionship between .the inorganic phosphate in sorbed and solid phases and that
In solution phase.
This report represents the first effort at a quantitative review of phos-
phate sorption literature. In this, review, discissions of sorption.mechanisms
as well as kinetic and equilibrium models are brought to focus 1n quantifying
and.predicting the relation between solution and solid phase concentrations
of phosphate, in .soil-water systems. Attempts at correlating Langmuir sorption
parameters with selected soil chemical properties will be discussed as a sim-
ple means of predicting the partition function for other soils given only the
chemical properties.
MODELS FOR EQUILIBRIUM SORPTION-DESORPTION OF PHOSPHORUS
Three equations, developed for gas-sol1d systems, have been adapted for
use in modelling the sorption of phosphate 1ons on charged surfaces. These
are the Langmuir, Freundlich, and Temlctn equations. Each equat.1on. can. be
developed from statistical mechanical considerations'of gas adsorption by
clean surfaces. Table 6-1 lists the assumptions underlying the derivation of
each equation. The added restriction of electroneutrality xzjn-t; = 0,. where
nj is the number of ions or ionized sites each with a charge of Zi, has made
applications of these equations to electrolyte systems somewhat empirical.
When applied to natural systems of a composite nature such as soils and sedi-
ments, these equations have been found to describe the adsorption of phos-
phate less than satisfactorily over a wide range of phosphate concentrations
(0-500 pg P/ml).
By far the most widely used model is the Langmuir equation which was
originally applied to phosphate adsorption on soils by Olsen and Watanabe
(1957). The simple Langmuir equation is written.
where, C = solution concentration; of phosphate (ng P/mT|,.S = adsorbed
PLANT PHOSPHATE
SOLUTION PHOSPHATE ^ ORGANIC PHOSPHATE
kM
A0S0RBE0 PHOSPHATE
79
-------
Table 6-1. Assumptions underlying the derivations of adsorption equations
Equation Assumptions and general methods for deriving equations
Langmuir Localized monolayer adsorption (adsorbate nonmobilo)
Heat of adsorption Q constant over entire monolayer
No lateral interactions of adsorbate molecules
Smax and k are independent of temperature
Rate of desorption set equal to rate of adsorption
Freundlich Localized monolayer adsorption
No lateral interactions of adsorbate molecules
Exponential frequency distribution f(Q) of adsorption
sites such that f(Q) = ae-Q/nRT
f(Q) combined with the Langmuir equation give the
Freundlich
Temkin Sites vary in Q according to Q = Q0 (1 - a9) where 0 is
the fractional surface coverage
Q substituted into Langmuir equation
80
-------
phosphate at concentration c (ug P/g soil), Smax 3 adsorption maximum at which
phosphate forms a monolayer on the solid surface (ug P/g soil), and k » a
constant related to the bonding energy of the phosphate on the solid surface
(ml/yg P).
Conceptually, Eq. [6-6] can be used to measure the amount of phosphate
that a soil can adsorb. The equation has been utilized in describing the
fertility status of soil phosphate (Olsen and Watanabe, 1957; Fox and Kamp-
rath, 1970). Since the parameter k is related to the bonding energy of phos-
phate to the soil, it has been regarded as an "intensity" factor by several
workers. The magnitude has been empirically and erroneously Interpreted as
the "bonding" energy of the phosphate to the soil. However, since k is
related to the energy of adsorption, it may find usefulness in describing
partitioning of phosphate between sol id and sol ution phases. The Smax term
has been related to "quantity" factors and as measure of the capacity of a
soil to retain phosphate. Both terms allow qualitative measures of phosphate
availability to agricultural crops.
The quantitative measurement of phosphate partitioning between solution
and solid phases remains largely undescribed. Causes of this deficiency rest
largely in the lack of detailed, knowledge of the structure and composition of
the solid surface with which the phosphate reacts. Adsorption potential
energies of surfaces 1n soil systems are not usually uniform 1n distribution.
Each mineral and type of organic matter can be expected to adsorb phosphate
with different adsorption energies. Surface areas contributing to each type
of adsorbent are not likely to be equal.
Because of this non-uniformity of site populations, Syers et al. (1973)
used a curve splitting technique, similar to the method developed by Shapiro
and Fried (1959), to describe phosphate sorption by Brazilian soils. The
Langmuir equation, originally proposed to describe sites of more than one
population (Langmuir, 1918)', was written
. _ V S 'max. cy k" SMmajt c r [5.7-1
s 1 + k'c 1 + k"c Lt) /J
where the symbols are as defined for Eq. [6-6]; primes refer to site popula-
tions 1 and 2, respectively. In a similar manner, Holford et al. (1974)
adapted the mult1-s1te Langmuir equation to phosphate adsorption. Their
equation was written the same as Eq. [6-7].
Holford et al. (1974) evaluated both the single-surface and two-surface
equations and found correlation coefficients of 0.99 for the single-surface
model (Eq. 6-6) and 1.00 for the two-surface expression (Eq. 6-7). Using re-
gression coefficients for k and Smax, they found that Eq. [6-6] underesti-
mates phosphate adsorption at 1owT0-2 ug P/ml) and high (> 12 ug P/ml-for
slightly adsorbing soils) equilibrium phosphate concentrations. Both of these
studies concluded that two populations of sites exist in soils for adsorption
of phosphate. The strongly adsorbing population was characterized by high
k values which were two orders of magnitude larger than thos« for the more
weakly adsorbing population.
81
-------
Several empirical modifications of the Langmulr equation were introduced
by Gunary (1970). Four equations were fitted to phosphate adsorption data of
24 soils by least-squares regression analysis and were written:
c/y = a + be [6-8a]
cy = a^ + b-jC + d^ [6-8b]
c/y = a2 + bgC + d2 c [6-8c]
log c/y = a3 + b3 Tog c [6-8d]
Eq. [6-8a] is seen to be in the form of the Langmuir equation and Eqs [6-8b]
and [6-8c] are modifications thereof. Eq. [6-8d] is a modification of the
Freundlich equation. From their statistical analysis, they concluded that
Eq. [6-8c] described the data better than the Langmuir equation. Eq. [6-8c]
always, gave Smax values that were 1.5 to 2 times that obtained from the
Langmuir expression. Unfortunately, no theoretical foundation for Eqs. [6-8a-
8d) was given and thus makes insight into the causes of phosphate adsorption
difficult.
The Freundlich adsorption equation was first applied to phosphate adsorp-
tion by Low and Black (1950). In their study of the correlation of phosphate
adsorption with release of A1 and $i from kaolinite, the equation used to ex-
press adsorption of phosphate was
s = kC1/n [6-9]
where, s = phosphate adsorbed (ug P/g kaolinite), k = a constant (not neces-
sarily equal to the Langmuir k), c s equilibrium concentration of phosphate
(pg P/ml), and 1/n = constant. The authors reported values of k = 0.562 and
1/n = 0.388 for their kaolijiit? sample.
Fitter and Sutton (1975) used a modified Freundlich equation
s + a = bCk [6-10]
where, s = phosphate adsorbed in the experiment (ug P/g soil), a = constant
.which •corrects, for- phosphate already present in the soil (jj.g P/g .soil), Q =
equilibrium concentration of phosphate (pg P/ml), and b, k ="constants. This
equation appeared to describe phosphate sorption data on 29 soils from
England. The value of a was determined by multiplying resin-extractable phps-
phate by a factor of 2.
Bache and Williams (1971) have used the Temkin for describing phosphorus
adsorption by soils. The Temkin equation is stated as:
r— = ir m (Ac) [6-n]
max
where, R = gas constant (cal mole"^ deg"^), T = absolute temperature (°K),
A,b are constants, and other symbols are as defined for Eq. [6-6]. The
82
-------
phosphorus adsorption Isotherms plotted according to the Tonkin equation were
reported to deviate from linearity in a manner similar to that from Langmuir
plots. Bache and Williams (1971) proposed a sorption Index, dS/d In C, ob-
tained from the slopes of a plot of S versus In C. Comparison of this sorp-
tion Index with other indices gave significant correlations in most cases.
For the soils tested by Backe ahd Williams (197?), correlation coefficients
of 0.99 and 0.28 were obtained, respectively* for regression of sorption Index
with the Langmuir constant and k.
The above expressions are all denied for gas adsorption by sol Ids and as
such do not explicitly contain terms which consider 1on1c Interactions. A
model of Ionic adsorption onto variable change mineral surface was derived by
Bowden et al. (1973, 1977). Their derivation was based on the Stern model of
the electrl cai double layer which- ts present at, the ..interface between e.lectro-
lyte solution and a solid surface composed of 1on1zable species. The model
unlike others, accounts for specific adsorption of ionic species from solu-
tion. This specific adsorption changes the potential
-------
6 = integral electrical capacitance of the region between the Stent
layer and diffuse layer (G can be computed using plots of the churtj;:
in charge of the Stern layer with the change in pH)
Nj = maximum number of ions adsorbed in the Stern layer
Z.j = charge on ion i
C.j = concentration of ion i in the bulk solution
F,R = Faraday and gas constants, respectively
a^j = activity of hydrogen ions in bulk solution
a. = charge density at the interface between the Stern and diffuse
layers
q =vcharge, density at the interface between the solid surface and the
Stem layer
¥d,¥s = potentials at the isopective interfaces
= permittivity of the medium in the diffuse layer.
Other models for the adsorption of gases and vapors on solids have been
introduced (Adamson, 1975). Each model attempts to describe the phenomenon
of adsorption from basic physical and quantum parameters. Often the models
apply to clean surfaces with uniform surface potentials quite unlike those
found in soil systems. Recently, models have appeared which include surface
heterogeneity in the treatment. In addition a promising area of study would
appear to be the inclusion of the additional condition of electroneutrality
in gas-solid adsorption models.
The models described above, explain the experimental data satisfactorily
in most cases for a given isotherm or solid phase. In nearly all cases,
statistical fits of experimental data showed that the models predicted phos-
phate adsorption with correlation coefficients of 0.9 or higher. Because of
assumptions made in model derivations, the "goodness-of-fit" does not neces-
sarily correspond to "correctness" of the model when applied to other solids.
Such solids may differ in bonding structure, porosity, crystallinity, and
content of impurities. As a consequence of these variables, correlations of
soil chemical and/or physical properties with sorption parameters obtained
using the adsorption models would not be straightforward. The degree to
which soil properties are correlated with sorption parameters has been test-
ed and is the subject of the next section of this report. If the models are
taken to describe phosphate adsorption adequately, the lack of correlation
of node! parameters with soil properties likely results from inaccurate char-
acterization of the adsorption mechanisms and poor description of sites.
84
-------
CORRELATIONS OF PHOSPHATE SORPTION PARAMETERS AND SELECTED SOIL PROPERTIES
Much effort has been directed/toward a mathematical formulation which
relates soil chemical and physical properties with phosphate sorption and
release. The requirement for a model which predicts the amount of phosphate
released from watersheds provides the need fbr such a function. The appro-
priate partition function will have several characteristics:
1) It will apply to a wide variety of soil conditions and compositions,
2) Predictions of phosphate partitioning will have a minimum amount of
error; e.g., less than or equal to a factor of two,
3) The function will be mathematically tractable to expedite computa-
tions, and
4) The function will be based upon soil properties which are easily
measured 1n the laboratory.
In order to develop such a partition function, two approaches, are ev1-
dent.. Firstj the soil can be divided into its particular set of organic and
Inorganic constituents and phosphate sorption quantified on each fraction.
In this way, a universal partition function based on a measurable set of soil
properties could, presumably, be derived. -Second, phosphate sorption^
desorption can be quantitatad on all Individual types of soil. Statistical
correlations of the sorption parameters with the soil properties would give
the partition function. Both approaches appear concurrently in the litera-
ture. If, however, one type of soil constituent dominates the sorptlon-
desorption process, it would seen worthwhile to Investigate 1n detail the
sorption processes unique to that particular constituent.
Several authors have statistically correlated.soil chemical properties
with phosphate sorption parameters. The scHl properties have Included pH,
CaCOj content,.particle size distribution, extractable Fe and Al (by several
methods), and organic carbon content. Phosphate sorption parameters have
consisted of a single-valued sorption index (phosphate adsorbed .at a single
level of added phosphate), constants from the Langmulr and Freundlich equa-
tions, and the Bache and Williams Index. These correlation .coefficients (and
linear regression equations, In some cases.} are presented In Appendix C,
Tables C1-C9. Most emphasis has been placed on the effect of Fe and A1 con-
stituents In the. soil which form relatively insoluble complexes and precipi-
tates with phosphate. Although the influence of organic matter on phosphate
adsorption has been debated,.organic matter appears to effect phosphate ad-
sorption in an indirect manner. Organically complexed Fe3+ and AT3+ are the
most likely sites for adsorption on organic matter surfaces (Weir and Soper,
1963 and Syers et al., 197l).
The oxyhydroxy Fe and Al constituents of the soils which have been re-
ported play a major role in determining the sorption of phosphorus In sails
(Ryde et al., 1977a,b). Based on such reports, we have attempted to normal-
ize the Langmulr sorption parameters with:respect to extractable Fe and Al
content of a wide range of soils aid sediments with an intent to derive
-------
"universal" coefficients applicable to all soils. This approach is similar
to that used to estimate pesticide adsorption coefficients based solely on
soil organic carbon.
A literature search was performed to obtain information from as many
soils as possible from which a correlation could be derived with a reasonable
amount of error. Of those papers reporting sorption parameters, nearly all
were based upon the Langmuir equation, though a few Freundlich constants were
found. In some cases, Langmuir sorption parameters were computed from pub-
lished isotherms. Langmuir parameters are tabulated in Tables C6 and C22
along with the corresponding descriptions of soils and methods in Tables Cll-
C21 and C23-C30, respectively. Those articles which contained chemical
analyses of Fe3+ or Al3+, in addition to sorption parameters, are summarized
in Table 6-2. Overall means, standard deviations, and coefficients of vari-
ation are given in Table 6-3. For purposes of analysis, natural logarithms
of the values, and parameters normalized with respect to Fe3+, Al3+, or Fe3+
+ A13+ are also listed in Table 6-3.
The Langmuir parameter S^x ranges from 4,420 to 12.6 yg P/g soil with a
mean of 434 ug P/g soil and a CV of 168%. Corresponding values for the
Langmuir k show a: range of 23.8 to 0.41 with a mean of 4.8 and a CV
of 109. Coefficients of variation were considerably lower for logarithmic
values of Smax and k, 25 and 101, respectively. An even greater improvement
in lowering the variability of Smax and k values was obtained when these
parameters were normalized with respect to extractable Fe and A1. The CV
values for logarithms of normalized parameters were on the order of 10-20 for
normalized k and 40 to 80 for normalized Sm, .
max
Two important conclusions emerge from the above correlations. First, a
significant relationship exists between extractable "active" A13+ and Fe3+ in
the soils tested within individual studies. The "active" Fe3+ and A13+
appear to be more consistently extracted by a reagent containing oxalic acid
(Saunders, 1965; Williams et al., 1958; Sree Ramulu et al., 1967), as an acid
oxalate solution (Tamm, 1932), or as ammonium oxalate-oxalic acid solution
(Schwertmann, 1964). In contrast to the oxalate methods, analyses which
employ dithionite to reduce Fe3+ to Fe2+ probably extract more Fe3+ than is
active in phosphate sorption. The interiors of iron-containing oxyhydroxide
crystals and interlayers Of phyllosilicates probably contribute "nonactive"
Fe and Al which is not likely to participate in sorption of phosphate. In
addition to differences in extractants used, inconsistancy in methods among
laboratories appear to account for the large variability observed in extract-
able Fe and Al. This variability is not surprising since chemical methods of
analysis employ several steps which vary from experimenter to experimenter.
Time of reaction with the reducing agent, temperature of the reaction mixture,
presence of light (in the method of Schwertmann, 1964), and pH of the buffer
system are some of the experimental variables. Lack of consistency indicates
a need for standardization of Fe and Al extractions when relating the data
to phosphate sorption.
Second, the single point isotherm has been the most popular in determin-
ing the phosphate sorption parameter. This method has not been uniform from
86
-------
Table 6-2. Sunrnary of phosphate sorption parameters and soil chemical prop-
erties used in linear regression analysis.
SOIL
REF*
t ml
*• ug P
^max
CDB
Oxalate
pg P/g soil
Fe3+
AU+
Fe3+
A13+
PH
ALLIGATOR
1
148
17.2
0.150
6.3
CRIOER
1
100
15.2
0.150
m
6.7
GRANADA
1
092
13.1
0.100
•
6.8
PAMBROKE
097
14.4
0-140
•
7.0
ZANESVILLE
1
123
12.6
0.110
7.0
VENAGO
2
847.0
0.380
0.110
4.7
HUMATAS
2
•
684^0
0,160
0.044
4.4
CATALINA
2
•'
683.0
0.220
0.056
4.9
CORDZAL
2
• '
468v0
0J10
0.044
4.2
EUTAM
2
•
390.0
0.200
0.078
4.7
AGAWAN
2
•
341.0
0.2OO
0.089
6.3
DAVIDSON
2
323.0
0.b30
0.096
6.5
GEORGEVILLE
2
•
262.0
0.850
0.096
5.5
COTO
2
• .
252.0
0.130
0.093
4.5
COOLVILLE
2
228.0
O.fclO
0,067
4.6
WANPUN
2
211.0
0.200
0.033
7.1
VALLERS
2
175.0
0.045
0.007
7.7
PUTNAM
2
«
128.0
0.210
0.033
6.0
EDINA
2
«
102.0
0.160
0.026
6.1
PORTSMOUNT
2
• -
126.0
0.039
0.067
5.0
WEBSTER
2
•
83.0
0.160
0.019
6.8
CLERMONT
2
9
58.0
0.170
0.026
6.5
NACOGDOCHES
2
•
55.0
1.750
0.110
6.7
SAO GABRIEL
3
4.80
73.0
0.020
0.026
0
012
0
009
5.2
CAMBIA
3
4.70
224.0
0.100
0.067
0
032
0
040
5.1
DUROX
3
10.90
990.0
0,410
0.190
0
026
0
033
3.7
WEBSTER
4
0.44
328.0
0.270
' *,
6.1
IDA
4
0.41
253.0
0.130
•
8.0
SOIL1
5
13.50
1040.0
0.930
0.440
4.2
S0IL2
5
23.80
451.0
0.140
o.no
5.2
SOIL3
5
9.90
1385.0
0.380
0.190
6.2
EGMONT
6
2.02
4420.0
0.120
0.780
7.1
OKAIHAU
6
2.51
2150.0
0.790
0.120
5.0
WAIKAKAHI
6
6.33
275.0
0.100
0.081
7.7
PORIRUA
6
2.72
461.0
0.790
0.120
5.0
LM52
7
7.11
112.0
0.170
«
#
LM67
7
6.44
124.0
0.600
* .
LM70
7
9.95
105.0
0.380
•
ROSELINS 1
8
1.69
287.0
0.360
0.094
0
280
0
100
6.4
BROUGHTON
8
4.89
209.0
0.380
0.094
0
120
0
TOO
7.3
Continued
87
-------
Table 6-2. (Continued).
SOIL
REF*
, ml
^max
yg P/g soil
CDB
Oxalate
pH
C' yg P
FeJ+ Al^+
FeJ+ AH+
ROSELINS 11
8
2.85
249.0
0.450 0.087
0.240 0.120
6.0
PAULDING
8
4.35
216.0
0.310 0.110
0.280 0.200
6.5
LENAWEE
8
0.80
244.0
0.580 0.170
0.290 0.130
5.4
BLOUNT
8
2.15
199.0
0.380 0.080
0.620 0.200
6.7
HOYTVILLE
8
1.49
258.0
0.290 0.080
0.190 0.150
7.1
*1 = Ballaux and Peaslee (1975); 2 = Vijayachandran and Harter (1975);
3 = Syers et al. .(1973); 4 = Singh and Tabatabai (1976); 5 = Barrow (1972);
6 = Ryden and Syers (1975); 7 = Holford and Mattingly; 8 = McCallister and
Logan (1978).
88
-------
Table 6-3. Summary of means, standard deviations,, and coefficients of
variation of sorption parameters and extractable Fe and Al.
STANDARD
VARIABLE* N MEAN DEVIATION C.V.
K
27
212.6
452.0
212.5
SMAX
45
434.2
728.8
167.8
FE1
45
0.3
0.3
97.1
ALT
35
0.1
0.1
122.9
FE2
10
0.2
0.1
87.1
AL2
10
0,1
0.0
61.2
PH
42
5.9
1.1
18.5
FEAL1
35
0.4
0.3
83.7
FEAL2
10
0.3
0.2
75.7
LNFEAL1
35
-1.0
0.8
-77.4
LNFEAL2
10
-1-5
1.1
-73.3
SMAX1
45
2225.6
5t3T.1
244.0
.SMAX2
35
5385.0
5132.1
95.3
SHAX3-
35
130T,5
1.1:01.0
84.5
SMAX4
10
5825.6
11570.5
198.6
SHAX5
10
5641.8
8846.8
156.8
SMAX6
10
2779.6
504612
181.5
IC1
27
1656.6
3552.3
214.4
K2
17
54.5.
59.1
108.2
K3
17
20.9
31.2
149.2
K4
10
105.4
166.1
157.5
K5
10
111.9
178.2
159.2
K6
10
53.1
83.7
157.6
LNSMAX1
45
6.8
1.3
19.5
LNSMAX2
35
8.2
0.7
9.0
LNSMAX3
35
6.8
0.9
14.3
LNSMAX4
10
7.5
1.3
18.4
LNSMAX5
10
8.0
1.0
12.9
LNSMAX6
10
7.0
1.2
17.5
LNK1
27
3.7
2.8
76.0
LNK2
17
3.5
1.1
31.8
LNK3
17
2.2
1.2
58.4
LNK4
10
3.2
1.8
58.7
LHK5
TO
3.6
1.5
41.9
LNK6
10
2.6
1.7
64.6
LNFE1
45
-1.4
0.8
-58.6
LNAL1
35
-2.5
0.8
-33.5
LNFE2
10
-2.0
1.2
-61.4
LNAL2
10
-2.5
0.9
-38.7
LNSMAX
45
5.3
1.3
24.5
LNK
27
2.3
2.4
105.4
*See Table 6-4 forexplanation of symbols used for variables.
89
-------
study to study. Saunders (1965) used a modification of the method developed
by Piper (1942). His modified method presumably fully saturates phosphate
sorption sites by shaking 24 hours in a pH 4.6 NaOAc-HOAc buffer containing
0.032 M KH2PO4 (500 pg P/100 g air-dried soil). Williams et al. (1958) used
Piper's method directly which saturates the soil with phosphate in 1 IN
(NH4)3P04 buffered at pH 4.0. Excess phosphate was removed with alcohol, and
the adsorbed phosphate was extracted with 0.125 N NaOH. In contract to ad-
soption at pH 4, Willi-ams et al. (1958) also measured adsorption at pH 2.6 by
shaking the soil in a solution of 2.5 volume % HOAc and KH2PO4 equivalent to
67 ng P/100 g soil. P adsorbed was computed as P added + acetate extractable
P (on untreated soil) - P remaining in solution. In another study, phosphate
retention was measured on California soils by adding 32P_iabelled monocalcium
phosphate to the soil (Sree Ramulu et al., 1967). Phosphate level was
10.2 yg P/5 g soil in H2O solution with no buffer.
In addition to Piper's method, Lopez-Hernandez and Burnham (1974) used
an adsorption index x/log C proposed by Bache and Williams (1971). A solu-
tion of phosphate (155 yg P/100 g soil), presumably KH2PO4 (although the
compound was not stated in the article) was used from which P adsorbed was
calculated by difference. The time of reaction was not indicated.
In contrast to the one-point isotherms discussed above, adsorption
maxima have been determined from multipoint Isotherms. Vijayachandran and
Harter (1975) developed adsorption isotherms on a variety of soils using a
1 hr reaction time in order to obtain an index of "reactive" sites. Ryden et
al. (1976) found however, that a reaction time of 40 hours was required for
equilibrium to be attained. Most Investigators have used a shaking time of
24 hours.
The trends indicated above indicate that Langmuir sorption parameters
may be correlated with a measure of "active" Fe and Al. As previously dis-
cussed, k is related (in the Langmuir model) to the energy of adsorption of
phosphate by solid surfaces. It is not considered to be a partition coeffi-
cient in that Kpartition = S/C, where S = amount of phosphate adsorbed per
weight of soil, and C 3 solution concentration of phosphate in equilibrium
with the solid surface. As stated in a previous section, the Langmuir con-
stant can be pictured in several ways. In the sense of -energies of inter-
actions,. k can be written as
k = k0eQ/RT [6-17]
where, k0 = N a tq/UitMRT)!/^ n = Avagadro's number, o = area of one adsorp-
tion site, Tg = residence time of a molecule on the surface when there is no
interaction between the molecule and the surface, M = molecular weight of the
adsorbing molecule, R 3 gas constant, T = absolute temperature, and Q = inter-
action energy of the molecule with the surface (Adamson, 1976). The Langmuir
k which is obtained from an adsorption experiment on a heterogeneous medium
such as soil represents a composite of all adsorbing surfaces. That is,
Qtotal =.z=]xi qi = RTln 1^ C6"18]
90
-------
where Qtotal 1s the total Interaction energy per weight of composite, qi is
the Interaction energy for a particular type of constituent per weight of
constituent in the composite, and xj is,the fraction of 1 In the composite.
Thus, an Increase in the value of tne observed k may indicate that an in-
crease in Q occurred.
Since the largest qf for phosphate adsorption on soils appears to be due
to "active" Iron and aluminum oxyhydroxides, the expected trend for k would
Increase exponentially with the fractional composition of those "active"
metals. However, as previously discussed, the measurement of the "active"
fraction is difficult. Figure 6-3 shows that, 1n contrast to the expected
trend, the k (normalized to Fe + Al) decreases 1n general with CDB extractable
Fe and Al.
By similar considerations, one would expect that S^x normalized to
extractable Fe + Al would be Independent of extractable Fe and Al. Apparent-
ly the situation 1s not so simple as Fig. 6-4 illustrates.
Several authors nave Indicated that Fe .aniil-AT 1h active fbms are re-
sponsible for sorption of phosphate. In addition to their summaries, phos-
phate sorption parameters and soil chemical properties which were collected
in the present study have also been plotted. Table 6-4 summarizes these
correlations; In general, our correlation, based on soils and rocks from
several locations,, show more significant results for.1) oxalateextractable
Fe and AT and 2) sorption parameters normalized with respect to the corre-
sponding extractable Fe and/or Al. These results, agree with those of
Saunders (1965) and Williams et al. (1958).
Data from several of the correlations In Table 6-4 were plotted
(Figures 6-5 to 6-12) In order to determine visually the trends Indicated in
Table 6-4 and the variations among Individual studies. The numbers plotted
in the figures represent the REF 1n Table 6-2. It is readily seen that any
relationship between sorption parameters and -soil properties obtained by sta-
tistical analysis of one group of soils cannot necessarily be extrapolated to
all soils. For example, the plot of In Smax versus In k 1n Fig. 6-5 shows
that intercepts and slopes of linear regressions of the data are different
for REF 3 and 8. Comparison of these references, shows that in the first case
In k is nearly Independent of In Smax whereas, 1n the second case In Smax 1s
Independent of In k. The differences apparently result from the inability to
quantify active Al and Fe. Differences In pH may account for some of the
variability.
Several conclusions can be drawn from the study of relationship between
phosphate sorption parameters and selected soil properties. Oxalate extract-
able Fe and Al are more significantly related to the Langmuir phosphate
sorption parameters than are CDB extractable Fe and AT, Oxalate extraction
appears to be more suitable for measurement of. the "active" Fe and Al than
CDB. Variability among authors 1s quite high and thus Indicates a need for
standarization of Fe and Al analyses as well as..methods for measuring phos-
phate sorption.parameters.
91
-------
/ AIPQ
u -4
7H -6
-10
2 4
6 8 10
PH
Figure 6-2. Solubility diagram for selected solid phosphate phases (Stumm and
Leckie, 1971).
-------
JS
S
$ 8
Q 60
E 40-
ra 20}-
3.
I*
< 6
I 4
5 2-
1-
°
oSoil pN>6 0 ° oo
•Soil 50
-------
lO
-p*
2000
1000
800
600
400
< 20C-
~
S 100
% 80
g 60
E 40
Q.
O)
3. 20h
^ 10
~ 8
6
4
2
1
Ll
X
CO
£
to
AA
A
•
A
A O
•
A
o o
o
o A
A A
gP O
o
2 4 6 810 20 40 60 100 200
CDB (Fe + AI), mmoles/g soil x 10^
Figure 6-4. Relationship between normalized S and CDB extractable Fe + A1 for
selected soils. 1 x
-------
Table 6-4. Summary of estimates obtained from linear regression correlations
of phosphate sorption parameters and extractable Fe and A!.
Dependent*
Variable
Independent Inter-
Variable cept
Std. error
of
Intercept Slope
Std. error
of slope
PR>F+,
%
R2 C.V.t+
LNSMAX
LNFEAL1
6.26
0.25
0.503
0.184
1.01
0.18 15.6
LNFEAL2
5.59
0.36
0.070
0.191
72.2
0.02 12.0
LNFE1
5.98
0.37
0.449
0.217
4.46
0.09 23.6
LNAL1
7.68
0.40
0.761
0.148
0.01
0.45 12.8
LNFE2
5.55
0.42
0.033
0.171
85.3
0.004 12.1
LNAL2
5.84
0,59
0.140
0.221
54:5
0.048 11.8
LNK
KNFEAL1
1.23
0.32
-0.T86
0.276
51 ..1
0.03 64.6
LNFEAL2
0.46
0.34
r0.414
0.180
5.1
0.40 56.2
LNFE1
1.00
0,90,
-0.937
0.542
9.6
0.11 101.7
LNAL1
1.58
0.67
0.090
0v300
7618
0:008 65.4
LNFE2
0.28
0.37
-0.393
0.154
3.36
0.45 53.7
LNAL2
0.063
0.62
-0.414
0.231
11.0
0.29 61.1
LNSMAX1
LNFE1
5.98
0.37
-0.551
0.217
1;5
0.13. 18.5
LNSMAX2
LNAL1
7.68
-0*40
-0,239
O.T46
11.1
0.075 8.9
LNSMAX3
LNFEAL1
6.26
0.25
-0.497
0.184
1.09
0.18 13.2
LNSMAX4
LNFE2
5.55
0.42
-0.567
0.171
0.05
0.80 8.7
LNSMAX5
LNAL2
5.84
0*59
-0.860
0.221
0.46
0.65 8.1
LNSMAX6
LNFEAL2
5.59
0.36
-0.930
0.191
0.12
0.75 9.3
LNKl
LNFE1
1.00
0.90
-1.937
0.542
0.15
0.34 63.1
LNK2
LNAL1
1.58
0.67
-0.910
0.300
0.85
0.38 25.9
LNK3
LNFEAL1
1.23
0«32
-1.186
0.276
0.06
0.55 40.4
LNK4
LNFE2,
0.28
0,37
-1.393
0J54
0.01
0.91 18.5
LNK5
LNAL2
0.06
0.62
-1.414
0.231
0.03
0.82 18.6
LNK6
INFEAL2
0.46
0.34
-1.414
0.180
0.01
0.88 23.2
K
SMAX
280.6
99.0
-0.130
0.095
18.4
0.07 209.1
LNK
LNSMAX
8.44
1.17
-1.163
0.215
0.01
0.54 73.0
~Symbols for variables represent the following: SMAX ° Lang.. Smax; K = Lang,
k; FE, AL ® extractable Fe and Al, respectively; FEAL 3 extractable Fe + Al;
suffixes 1, 2 on independent variable 3 citrate-dithionite-blcarbonate and
oxalate extractant, respectively; suffixes on dependent variable = normalized
variable with respect to the corresponding Independent variable; LN = natural
logarithm of variable.
^Probability level at which regression is significant. PR>F = 0.01X fs equiv-
alent to a = 0.0001.
^Coefficient of variation.
95
-------
K£>
cr>
32
24
1.6
f OS
O.O
-OS
~b
5
3
2.0 2.8 3.6
4.4 52
I n S
60 6.8 7.6 8.4
MAX
Figure 6-5. Relationship between Ink and InS for selected soils. Numbers refer
to REF in Table 6-2. mx
-------
is
9.0
7.8
6.6
x
<
2 5 .4
42
30
,6
2 2
% 2
6
a
e
5
3
6
2
a
6
-33 -2.7 -2.1 -15 -09
»n (CDB Fe * Al)
-03
03
0.9
Figure 6-6. Relationship between lflSmax an(J 'n (Fe + AT) for selected soils.
Numbers refer to REF in Table 6-2,
-------
6
lO
oo
80
70
£ 60
DQ
Q
(J
50
(n
E
CO
£ 40
30
^ 2
I 2
2
5
2 3
8
J3
2
8
-30 -24 -18 -1-2 -0-6
In (CDB Fe*AI)
00 06
Figure 6-7.
Relationship between lnCSmay/fCDB Fe + Al)] and ln(CDB Fe + Al) for
selected soils. Numbers refer to REF in Table 6-2.
-------
vo
to
10.0
< 92
4
1)
g 64
ML. 76
68
60
i
-4.2
8
8#
8
8
-3.6 -30 -24 -1.8
In (ox Fe> AI)
-12
-1.6
00
Figure 6-8. Relationship between lnCS^/foxFe + A1)] and 1ri(oxFe + A1) for selected
soils.. Numbers refer to REF In Table 6-2.
-------
56
40
o
o
j*:
c
24
08
-0-8
¦ 3
8
-42 -
-I I L.
8
8
8
8
8-
8
3-6 -30 -24 -1-8 -12
In (Ox Fe)
¦ ¦
-06 00
Figure 6-9. Relationship between Ink and ln(oxFe) for selected soils. Numbers refer
to REF in Table 6-2.
-------
72
5 6
40
^ 24
c
08
-08
i i
8
8
8
8
8
8
8
¦ ' ' ¦ ¦ I J I L_
-42 -36 -30 -24 -18 -12 -06
In (ox Fe* Al)
Figure 6-10. Relationship between Ink and ln(oxFe + Al) for selected soils. Numbers
refer to REF in Table 6-2.
-------
o
ro
6-0
50
-------
50-
3
3
o
bO
40
< 30
+
* 20
S
£
1-0
OOL
j j_
8
8 a
88
8
8
_i JU
-42 -3 6 -3-0 -24 -18 -12 -06
In Cox Fe ~ Al)
00
Figure 6-12. Relationship between ln[k/(oxFe + Al)] and 1n(oxFe + Al) for selected
soils. Numbers refer to REF In Table 6-2.
-------
ESTIMATION OF A PARTITION COEFFICIENT FOR PHOSPHATE
We describe here the first known attempt to develop a phosphate partition
function Kg which is based on soil chemical properties. The Langmuir equation
is used as the adsorption model and literature data are used to compute values
for K[|. Because of extreme variability in the relationship between soil
chemical parameters and phosphate sorption, the attempt did not successfully
describe Kq in a meaningful way.
A partition coefficient Kq which describes the relation between solid
forms of phosphate (adsorbed phosphate and precipitated phosphate compounds)
and solution phosphate ideally can be expressed in terms of Langmuir sorption
parameters. Conditions which effect the magnitude of Kq include:
1) phosphate concentration in the solution in contact with the solid phase,
2) time after which phosphate has been placed in contact with soil before a
desorption event, 3) time elapsed during a desorption event, 4) solution pH,
and 5) soil chemical properties. Amounts and crystallinities of Fe and A1
hydrous oxides appear to dominate other properties in acid soils, and solu-
tion Ca2+ concentrations in basic soils are significant.
Although there appears to be no sound theoretical basis for using the
Langmuir equation to describe ionic adsorption by solids in aqueous systems,
the model allows the calculation of parameters which are useful on an empir-
ical basis. The Langmuir equation is used as a mathematical model in this
report, primarily because of the large volume of Langmuir sorption parameters
reported in the literature. Other equations (Freundlich, Temkin) are being
tested to determine their usefulness in computing a Kp.
A partition function for phosphate sorption for a single soil can be
described by the Langmuir equation. Rearrangement of the Langmuir equation
gives for the partition coefficient, Kg,
KD [6-19]
Based on this equation, K[) is a function of the equilibrium solution concen-
tr'ation' of" phosphate. A few computations using the data in Table C31 show
that the dependence of Kp upon C follows the expected trend.
However, if kC « 1, Eq. (6-19) can be put into the form,
kD - I - ksMx
In' this approximation, Kq is independent of C, and S is directly proportional
to C. Thus, Eq. (6-20) represents a linear adsorption isotherm or the
Freundlich equation in which the exponent of C is equal to 1. Figure 6-13
shows a plot using data from Tables C22 and C31 which illustrates the suit-
ability of this approximation. Large deviations from the linear plot occur
in the soil with the higher k.
104
-------
Isotherm
Isotherm
49
o>
SYMBOL ISOTHERM
49
0.4 06 08
02
Figure 6-13. Phosphate sorption Isotherms for Isotherms 5 and 49 (Tatle C22).
Solid. Tines were computed from S = kSi. C using the parameters
indicated in the figure.
10S
-------
Errors involved in using Eq. (6-20) can be evaluated by combining
Eq. (6-19) and £q. (6-20) to give
S'/S = T + kC [6-21]
where S1 = kS^v C, and 5 comes from Eq. (6-19). The quotient S'/S represents
the degree to which S' approximates S. Figure 6-14 shows a plot of Eq. (6-21)
as a function of C up to 2 ug P/ml in the equilibrium solution (a reasonable
limit of phosphate concentrations rn soils) for various values of k. A factor
of 2 was taken to be a reasonable limit for S'/S. The figure shows that for
low values of k (examples can be taken from Tables CIO and C22), S'/S is
small, and S' thus represents an acceptable approximation to S. As long as
the solution concentration of P is equal to or less than 1/k, an acceptable
error results.
Prediction of phosphate sorption behavior and a partition function on an
unknown soil is associated with appreciable errors. The above treatment has
regarded Kn (=kSmax) as an intrinsic property which is characteristic of the
behavior of a given soil. Ko values, estimated from the compilation of data
in this report, were found to range from 100,000 ml/g soil to 1.0 ml/g soil.
A mean Kg plus or minus a standard error would appear to have less than
..desirable value in describing adsorption-desorption behavior.
We attempted unsuccessfully to quantify Kp as a function of 1) extrac-
table A1 and/or Fe, 2) pH, and 3) exchangeable Ca2+ content of soils using
literature data. Several soil chemical parameters, which are difficult, if
not impossible, to quantify from the literature, introduce variability in Kp.
Figure 6-15 shows a plot of Kd and CDB extractable Fe + Al. The correlation
between Kp and CDB Fe + Al is not satisfactory, as would be expected from the
statistical analyses presented in the previous section which indicate a
probable relationship between k and S^x. Normalization of Ko with respect to
CDB Fe + Al yields similar results as shown in Figure 6-16. Degree of
crystal Unity of Fe and Al oxtiy.droxides and the concentration range to which
Kq applies"-(i .e,, whether kC « 1) also introduce variabilities in Kq.
Because of the concentration dependence of Kq, another factor which
affects its magnitude is the elapsed time after an adsorption or desorption
event. During this time the phosphate comes to equilibrium with the soil
solution..^ Barrow and Shaw (1975). have given a semiempirical relationship
which included"the times during "which added phosphate came to equilibrium -wi.th
the soil and the time during which desorption occurred. Their model is des-
cribed in more detail in a later section.
An important feature of their model described both adsorption and de-
sorption limbs of the isotherm as they changed with time of incubation with
100 ug P/g soil. Figure 6-17 illustrates the non-singularity involved in such
adsorption experiments on one soil. An estimate of the amount of phosphate
entering the soil solution during a desorption event can be obtained from such
a plot if S and C are known when the desorption begins. Kinetics of the
adsorption and desorption apparently control the degree of non-singularity.
Table 6-5 lists the approximate Kn values obtained at various times for soil
incubated for 18 days at 42°C with 1000 pg P/g soil, and solution:soi1 ratios
106
-------
2.0
k=i.o
Q5
18
1.4
12
1.0
0.4
2.0
08
12 1.6
C,jjg P/ml
Figure 6-14. Degree of error 1n using S' = kSmaxC compared to the Langmulr form,
S = kSmaxC/(l + kC), as a function of equilibrium phosphate concen-
tration for various values of k.
-------
176
144
'O
112
o
80
o
oo
48
6
16
6
3
88 g
8 8 8
8
Q2
0.6 10 14 18
CDB Fe*AI mmoles / g soil
2.2
Figure 6-15. Relationship of the approximate expression for Kp(=kS,j,ax) and CDB Fe + A1
for selected soils. Numbers refer to REF in Table 6-2.
-------
44r
5
s
36
<28
J?
§20
u
12
6
02
8
_8_
6
6
06 10
CDB Fe ~ Al
14
mmoles/g soil
1B
22
Figure 6^16. Relationship of the approximate expression (Kq = kSmax) normalized with
respect to CDB Fe + Al and CDB Fe + Al for selected soils. Numbers
refer to REF In Table 6-2.
-------
cn
1000
cn
~ 800
600
cl 400
a a 2 days incubation at 42
o* 18days incubation at 42
200
O 20 4.0 6.0
Solution Concentration
jug P/ml
Figure 6-17. Phosphate sorption-desorption isotherms for a soil incubated in the
presence of phosphate (Barrow and Shaw, 1975).
-------
Table 6-5. Effects of time of desorptton and solution/soil ratio during
desorption on Kq values obtained on a so>1l previously incu-
bated with phosphate.
Soln.:
Time,
K0.
Soil ratio
br
ml/g soil
5:1
1
1,245
4
828
8
620
500:1
2
11,127
6
8,120
17
5,750
Ill
-------
of 5:1 and 500:1. Lack of kinetic data prevents evaluation of this effect
on a broad scope of soils. The.following, conclusion'can. be arrived at 'on the
basis -of the analysis presented in this section.
1. A standardized method for determination of sorption parameters is re-
quired in order for consistency from laboratory to laboratory.
2. A partition coefficient can be calculated as the product kSmax, based
upon the assumption that the Langmuir equation expresses the true adsorption.
This product allows the estimation of solution-soil partitioning of phos-
phorus up to a solution concentration equal to 1/k within a factor of two.
3. The K[) normalized with respect to extractable Fe + A1 is not significant-
ly related to Fe and A1 as in the case of pesticide adsorption described by
koc*
PHOSPHATE IN RUNOFF WATERS
Modeling phosphate concentrations in runoff waters requires a knowledge
of 1) quantities of phosphate already present in the soil, 2) distribution of
phosphate with particle size of the soil, 3) the rate at which phosphate is
released from soil, and 4) the quantity released during the time of a desorp-
tion event. A review has recently, appeared which discusses transformations
and quantities of phosphate in runoff (Logan, 1980).
The effect of the quantity of phosphate already present in the soil has
been considered by Barrow and Shaw (1975) and was discussed in the previous
paragraph (Fig. 6-17). Apparently, phosphate was held in a less soluble form
after soil with added phosphate was incubated. The fraction of phosphate
released from the soil during the equilibrium desorption experiment varied
from 0.03 to 0.16 (Fig. 6-17). Thus, based on the data by Barrow and Shaw
(1975),. a soil containing 500 mg P/g soil, may be expected to release 15 mg
P/g soil, in equilibrium with a solution containing 2 mg P/ml.
Runoff sediments become enriched in finer particle-size fractions and
the phosphate is more concentrated in the sediment because of its association
with'silt and cTay fractions. The particle size .distribution of the runoff
sediment is a function of the erosion rate, nature and geomorphological
.position of the ,soi 1 -(Logan, 1980).. Plant nutrients, including phosphate,
were enriched in the finer fractions of sediments when compared to concen-
trations existing in the soil before erosion (Stoltenberg and White, 1953).
Total phosphate was also concentrated in the silt and clay fractions of two
New Zealand soils (Syers et al., 1969). An approximately linear relation-
ship between available phosphate in eroded sediment and solution phosphate
concentration was found in a controlled field plot study on a' Russell silt
loam soil (Romkens and Nelson, 1974). They proposed a simple laboratory test
to measure phosphate concentration in runoff water. The method involved
overnight equilibration of soil with 0.1 N NaCl and measurement of extract
phosphate. However, this measurement was not related to soil chemical prop-
erties.
112
-------
The rate at which phosphate 1s released from the soil was discussed in
the previous paragraph (Table 6-5).
EXPERIMENTAL CONDITIONS WHICH AFFECT MEASURSIENt OF PHOSPHATE SORPTION
PARAMETERS
In selecting parameters for the phosphate adsorption model, standard-
ization of measurement procedure by which the parameters are measured seems
to be of first concern. The following are the factors Which need to be taken
into consideration.
a) Temperature effect. In relating the amount of phosphate adsorption
to solution concentration, constant temperature is essential because the re-
lationship is temperature dependent. Gardner and Jones (1973) equilibrated
an Aridisol (Calciorthid) and a Spodosol (Fragiothod) from Idaho with a
O.OTM CaClg solution containing varied amounts of phosphate at 5° and.20°C
and found that the adsorption rate decreased as the equilibration temperature
was lowered. The rate of desorptlon was affected similarly. They found
phosphate in the equilibrated solution at 5e and 20 °C. The reduction reached
23 and 15?, respectively, for Fragiorthod and Calciorthod with high phosphate
pretreatment. Barrow and Shaw (1975) conducted experiments in which soils
with varying amounts of added phosphate were incubated at different tempera-
tures. The amount of phosphate extracted by shaking 15 minutes in 0.01M
CaCl2 decreased as incubation temperature increased. Conversely, when soils
were incubated at one temperature and phosphate was measured at another, an
increase In temperature of measurement resulted in high, solution concentra-
tions of phosphate. Both of these effects can be explained on the basis of
kinetics of phosphate transformation from an adsorbed to a crystalline pre-
cipitate phase in a system which is not at true equilibrium when measurements
were taken.
b) pH effect. As the pH of the soil usually affects the chemical re-
activity of some soil constituents, its. effect on phosphate adsorption has
been taken into consideration;in many phosphate' Sorption- studies. There were
studies where no attempt was made to control the pH of the suspension, as
Table C23 indicates. Bache:and Williams (1971J obtained the value of their
proposed single-point phosphate sorption index, x/log c, for a limed field
soil at pH 6.5 which differed only by 3%.from the value obtained on its un-
limed. analogue,at. pH .4.3, They suspected that the effects of j>H in the. range
normally encountered in acid soils are likely to be small compared with dif-
ferences between soils. Lopez-Hernandez and Burnham (1974b) did not find a
significant correlation between pH and phosphate retention for a group of
mixed soils but they did find a highly significant decrease in retention with
increasing pH for a group of pedologically similar soils differing mainly in
ptt. In an earlier study, Obihara and Russell (1972) showed that,the.amounts
of phosphate adsorbed by the soils decreased substantially with increasing
pH with two breaks in the curves at about pH 6.4 and 11.6.
c) Salt effect.. In phosphate adsorption studies, phosphate has often
been added with an electrolyte, usually a neutral salt such as NaCl, KC1, or
CaCl2- A recent study by Helyar et al. (1976) . showed that the phosphate
adsorption isotherm for a 11 gibbsite suspension in the equilibrium phosphate
m
-------
concentration range of 0.1 to 1000 yM was not affected by the presence of
0.02M NaCl -or KC1 or 0.01M. MgCl2- However, increasing CaCl2 fronrO'to
0.02M increased the phosphate,adsorption over the range of 1-100 pM final
phosphate concentration after 24 hours of equilibrium at pH 5.5 and 26°C.
They proposed that the affect of Ca on phosphate adsorption was not due to
bulk precipitation of di- or octo-calcium phosphate but rather epitaxial
complexation of 2(H2P04~) ions with Ca2+ on the 001 surface of gibbsite.
Ryden and Syers (1975) and Ryden et al. (1977) working with soils found that
ionic strength and cation species influenced the amount of adsorption
throughout the final phosphate concentration range of 0 to 10 pg P/ml during
40 hours of contact. At infinite time, the equilibrium concentration was
independent of ionic strength and cation species. They concluded that the
composition of the solution affected only the rate at which equilibrium was
attained. Singh and Tabatabai (1978) equilibrated 3 g of soil with 30 ml of
0.01M solutions of various salts containing 0-50 pg P/ml by shaking at 23°C
for 24 hours and found that chlorides of K, Na, Li, Ca, and Mg, Ca sulfate
and nitrate, and KHCO3 increased the phosphate adsorption by 6 soils they
used.
d) Time effect. It has been generally agreed upon from the kinetic
studies that phosphate adsorption involves two stages of reaction; the first
proceeds rapidly and the second may continue for many weeks or months. The
initial rate of adsorption is complete within a few hours and a slower re-
action continues for longer periods. The time required to establish equili-
brium depends on the soil and clay materials. The equilibrium time used by
various workers ranged from 16 hours (Larsen and Widdowson, 1964) to
48 hours (Ryden et al., T977). Hope and Syers (1976) found that phosphate
adsorption isotherms of three soils with widely different phosphate adsorp-
tion capacities showed a dependence on solution to soil ratio at a final
phosphate concentration of 0.5 pg P/ml after 40 hours of contact. However,
adsorption equilibrated continued in samples up to 146 hours. Ryden et al.
(1977) found an initially rapid decrease in solution phosphate concentration
with soils, hydrous Fe oxide gel, and natural goethite. It was followed by
a much slower decrease between 43 and 192 hours. They concluded from the re-
solution of the sorption isotherms that the increase in phosphate sorption
with time involved an appreciable shift of phosphate from a more physically
sorbed form to a chemisorbed from involving the diffusion of- phosphate into
"structurally porous" amorphous material
e) Effect of accumulation of CO2 and aeration. The redox status of
soil suspensions while shaking or stirring has been shown to be an important
factor in the sorption and release of phosphate (Patrick and Khalid, 1974).
The degree of aeration is also important in order to prevent accumulation of
CO2 in the sample containers. The variability of CO2 concentrations in soil
solutions causes a variation in equilibrium phosphate concentrations (Larsen
and Widdowson, 1964).
f) Concentration range. Concentration ranges of phosphate used by
various authors in phosphate adsorption studies varied considerably. Both
low and high concentration ranges have practical values. While the low
ranges reflect the phosphate concentration in soil solution, the high concen-
tration range may simulate the situation which may be found in the fertilizer
114
-------
zone. Rajan (1975) found several Inflection points in the phosphate adsorp-
tion isotherms when a large amount of phosphate was added. Effects on Kq
were discussed in a previous section.
g) Solid to solution ratio. The effect of solid to solution ratio on
phosphate adsorption has been noted (Larsen and Court, 1960; Fcrdham, 1963).
However, a great variation in the solid-solution ratio has been found in
published reports. Larsen and Widdowson (1964) studied the soil to solution
ratio effect on equilibrium phosphate concentration 1n O.OlMCaCl2 solution
in their phosphate potential study and suggested that the ratio effect was
Induced by CO2 due to a variation 1n biological activity and soil aeration.
The effect of COz on phosphate adsorption and release was interpreted by
Patrick and Khalid (1974) as resulting from microbial reduction of Fe3+ in-
soluble phosphates to the more soluble Fe2+ form. Recently, Hope and Syers
(1976) found that more phosphate was adsorbed by the soil at a soil/solution
ratio of 1:5 than 1:40 for a given level of phosphate above a final concen-
tration of 0.5 yg P/ml. However, the phosphate adsorption from various soil/
solution ratios appeared to be the same at equilibrium when the phosphate
concentration was estimated by extrapolation of the linear relationship be-
tween solution phosphate and the reciprocal of time to zero (or t •*¦ <»).
h) Effect of previously accumulated phosphate. Bache and Williams
(1971) have shown that the same two soils with different amounts of previous-
ly sorbed phosphate gave two different adsorption Isotherms. When the ini-
tially sorbed phosphate was taken into consideration, the two Isotherms
became coincident. Barrow (1974) showed that after 12 months of incubation
and 3 years 1n the field, previous phosphate additions reduced the capacity
of the soils to adsorb further phosphate. Previously sorbed phosphate was
less exchangeable which suggested that it had been converted into a form
which occupied the sites and blocked than from further reaction. The effect,
however, was not linear.. Low levels of phosphate application produced a
larger effect per unit of added phosphate than high levels.
Isotopically exchangeable phosphate
In order to develop a measurement of the amount of phosphate available
to plants, several workers have .adapted, radioisotopic techniques to soil
phosphate chemistry. Such experiments record the fraction of the radio-
isotope (usually 32p_iabelled phosphate) left in solution after .a. period of
equilibration. The technique has several advantages from an experimental
point of view; however, interpretations of the disappearance of the radio-
isotope from solution vary among authors. Advantages of the radioisotope
method have included: 1) the absence of complexing reagents, acids, or bases
comnonly employed for phosphate extracting Which alter the chemical composi-
tion of the soil-water system (Amer et a!., 1955), and 2) the potential of
the method to distinguish between, the various mechanisms of phosphate dis-
appearance (Russell, et al, 1954; lieser, et al<, 1945). However, the mathe-
matical treatment of the isotopic exchange kinetics 1s'usually based upon an
equation for a group of simultaneous first order reactions (Russell et al.,
1954), or expressions which include a consideration for the diffusion of the
ion to the reacting surface-(.Lieser, 1.945)> The formulations: based upon
115
-------
phenomenological classification of reactions provide little insight regarding
reaction mechanise as in the case of mechanistic formulations in reaction
kinetics.
Disappearance of radioisotope labelled phosphate from solutions appar-
ently follows a similar reaction sequence as unlabelled phosphate. That is,
the radioisotope unremoved by a rapidly exchangeable pool of phosphate in
hydroxyapatite slurries reduced 32p activity to solution levels of 10« of
the initial activity after 100 minutes of reaction time. Slower disappear-
ance continued for 400 minutes (Avnimelech, 1968). The rapidly exchangeable
32p was assumed to be complete within a few seconds after dilution. An inter-
mediate pool continued for several minutes, and a slow pool removed 32p from
solution for several hours. The three reactions occurred simultaneously, of
course. The author suggested that the intermediate pool was identical with
a layer on the surface of the original mineral.
Experiments with soils have generally shown that a slowly exchanging and
a rapidly exchanging fraction exists under field conditions. The process of
isotopic reaction with the rapidly exchanging fraction is complete within
24 hours while the slower exchange reaction occurs for longer periods
(Talibudeen, 1958).
The radioisotope-exchange technique has also been used to estimate
existing adsorbed phosphate in soil matrices (Holford et al., 1974; Bache
and Williams, 1971). From the relation (3-22), adsorbed phosphate can be
estimated.
Pe " Psol + Ps " "WF CO"22]
where Pe = total isotopically exchangeable P, Psoi = total phosphate in
solution (including nonradioactive species), Ps = isotopically exchangeable
adsorbed .phosphate, and F '= fraction of radioactive phosphate exchange after
24 hours.• This treatment assumes that only- surface adsorbed phosphate is
measured.
MATHEMATICAL EXPRESSIONS USED TO DESCRIBE TIME-DEPENDENCE OF PHOSPHATE
SORPTION
In describing the time-dependence of phosphate sorption-desorption by
soils, most researchers apply rate expressions commonly used in dealing with
solutions. Extrapolations of these expressions to the case of solution-solid
kinetics presents several problems. The concentration terms in kinetics ex-
pressions implies that any molecule or ion of reactant is capable of reaction.
In liquid-sol id systems however, only those atoms or ions in the surface
layer and not those in the interior of the particle are available to react.
Thus, a factor describing the concentration of reactive surface sites should
be included in such rate expressions. An alternative approach has been used
which expresses surface concentrations of phosphate in terms of an adsorption
model.
116
-------
Several attempts of describing the kinetics of phosphate sorption-
desorption have been reported in the literature and are sunmarized in this
section.. Rate expressions derived from simple reaction schemes appear to des-
cribe the phenomenon of phosphate sorption rather than the mechanism of the
sorption process. Tib studies were found which reduce the solution-solid
system to a set of elementary reactions from which the rate law was derived.
In general, 1t 1s not possible to deduce the mechanism of a reaction from the
rate law alone (Smith, 1970). Other experimental methods such as spectrosco-
py must be used to fully elucidate the reaction mechanism.
However, the rate laws described in the literature for the sorption of
phosphate do allow the experimenter to empirically calculate the importance
of several variables relative to phosphate partitioning. Of these variables,
the presence of certain mineral species-and their crystallinities, time, and
temperature seem to.be the most influential in controlling phosphate sorp-
tion-desorption.
Several authors have developed mathematical expressions to describe the
appearance and disappearance of phosphate from solutions in contact with
solids of various compositions. One form of the rate expression 1s the para-
bolic diffusion law (Laidler, 1965) which may be written as
C = R \/T+ a [6-23]
where C is the quantity of substance appearing In .solution 1n time t, R is a
measure of diffusion and a is a constant. Cooke (1966) used an empirical re-
lation Eq. (6-24) to describe phosphate release from British agricultural
soils; his equation 1s as follows:
P " R J~t + b [6-24]
Where P is the quantity of phosphate released in time tV R is a measure of a
diffusion and b is a constant. Both R and b.were suggested to describe
capacity and intensity factors of the soil to-iuiiP'ly. phosphate to the soil
solution. Unfortunately, no correlation of R or b with soil chemical param-
eters was reported. Their results indicated that phosphate release was dif-
fusion controlled.
Another form of Eq. (6-23) was used by Evans and Jurlnak (1976) to de-
scribe phosphate release from a desert soil with .high,pH and carbonate1 con-
tent. In their experiments, release of phosphate from the soil to an anion
exchange resin was followed with time according to a scheme involving three
simultaneous first order reactions outlined by Amer et al. (1955). A kinetic
expression for each reaction may be reduced to
log (C0- C) = log Cn- kflt [6-25]
where C0 1s the Initial amount of unadsorbed phosphate present which partici-
n .
pates in the nth reaction (C 1s equal to £ C«), C is the amount of phosphate
0 1=1 1
-------
released from the soil and adsorbed by the resin after time t, kp is the rate
constant of reaction n, and Cn is the amount of phosphate initially present
for reaction n in the unadsorbed phase.
For the soil used by Evans and Jurinak, analysis of the data showed that
the phosphate release could.be adequately described by three simultaneous
first-order reactions. Reaction durations were reported at approximately
1 to 2 hours, 8 to 16 hours, and 2 to 4 days, respectively. Rate constants
and activation energies from the studies are listed in Table 6-6.
The above treatment by Evans and Jurinak was derived from the consider-
ations of Amer et al. (1955). In Amer's treatment, three "desorption" re-
actions (reactions which cause appearance of phosphate in solution) were
assumed to occur simultaneously. Phosphate desorted from the soil into
solution was adsorbed by an anion exchange resin and could be designated as
Pri, Pr2 and Pr3, respectively for each of the fast, intermediate, and slow
reactions. The fundamental rate expressions relating phosphate adsorbed by
the resin with time were as follows:
dPn .
dt
kl'Psl
[6-26]
dP*_
dt
k2 Ps2
[6-27]
and
dPr3_
dt
k3 Ps3
[6-28]
where Pri are as described above, k-f' are rate constants, and Psi are the
amounts of unadsorbed soil P that are present at time t. Integration of the
above expressions gave Pri = Cj (1 - e -kit) with Psn- = Ci - Pr-j; when the
three resulting expressions are1 combined equation (6-29) resulted:
Pr ' Prl + Pr2 + Pr3 " "
(Cle~fc' 1 * C2e"k2't+ C3e"k3 t) [6"29]
where C-j are the amounts-j>f unadsorbed phosphate remaining on the soil
associatedwith'each reaction at t = 0. By a series of computations, the
three rate constants were evaluated to give k] = 2.6 X 10-3 sec-1,
kg' - 1.25 X 10-4 'sec-l, and k3 = 4.2 X 10-6 see*! for four Iowa soils.
Another rate expression was given by Kuo and Lotse (1974) for phosphate
sorption by kinetic and gibbsite. Their treatment was based upon the
Freundlich adsorption equation and was written
£=-k(P0-P) [6-30]
118
-------
Table 6-6. Rate constants and activation energies for indigenous phosphate
release from Thiokol silt loam.*
Surface so1l:0-3 cm Subsoil:28-40 cm
TPS 3o®5 ! TPc 5o*c
ki (sec-1)
.19X10"1*
. 51 xl 0-®4
.30x10"**
^xlO"4 .41X10"4*
. 41 xl O"1*
k2 (sec"1)
.llxlO'5
.27x10"5
.16x10"5
.15x10"5 .llxlO"5
.26x10"5
k3 (sec-1)
.87xl0~6
.13x10"6
.12xl0"6
. 15xl0"6 .93x10"6
.19x10"®
AE(ji(kcal/mole)
2.8
3.3
A^difkcal/mole)
2.3
3.3
AEditkcal/mole)
2.0
T.7
*From Evans and Jurinak (1976),
T19
-------
wnere P is the amount of phosphate in solution, P0 is the amount of phosphate
already adsorbed by the soil, and.k is the rate constant. The factor
(1 - e-^t) was inserted into the Freundlich equation (x = kC"/m) to give
xm = k(l - e'k2t)Cn
where x was the amount of phosphate adsorbed per gram of soi1, k was the
Freundlich constant, k2 was the rate constant, C was the solution phosphate
concentration, and m and n were constants. Rearrangements and transforma-
tions led to the expression
x = A1/m Cn/m t1/m [6-31]
where A = kk2.
Eq. (6-31) was approximated by
x = kCQ t1/m [6-32]
where C0 was the initial phosphate concentration, and kC0 = A^m Cn/'m. In
the latter case, n/m was assumed to be much less than unity; however, Low and
Black (1950) reported an n/m value of 0.388 which is hardly "much less than
unity" as the authors state. Unfortunately, none of the rate constants were
evaluated by Kuo and Lotse.
Kuo and Lotse (1972) also studied the time-dependent adsorption of phos-
phate by CaC03 and Ca-kaolinite. The basic rate expression obtained by them
was derived from a simple Langmuir adsorption model and was
x)(M - x) - k^ x [6-33]
where x is the amount of phosphate adsorbed by the soil, C0 is.the initial
concentration of phosphate, M is equal to the amount of phosphate required
to form a monolayer on the soi-V.surface, and k] and k_i are forward and
reverse rate'constants, respectively. Integration of Eq. ('6-33)"yields,
1n {a'+'b } = +' ln ( f~Hb C6-34]
where A = [1/4(CQ + M + ^-*-)2 - CQM]1/2
and k , ,
B = 1/2 (CQ + M + !-)
Only one of two possible solutions for k] was evaluated by the authors (none
was given for k_i), and their results are presented in Table 6-7. It should
be noted that ki is a mixed second order rate constant.
120
-------
Table 6-7. Rate constants of phosphate: adsorption by CaC03 and
Ca-kaolintte.
Initial .
P K1
concentration
CaC03
Ca-kaolinite
ppm
1/ppm second
1/ppm hour
0
0.12
1
0.086
2
0.070
4
0.043
0.0058
12
0.0095
20
0.0017
-------
Based on a three-site Langmuir-type adsorption equation, McLaughlin et
al. (197-7) developed a time-dependent adsorption equation for phosphate on
hydrous ferric oxide gel... .Th^ir equation was as follows:
PT = amount of phosphate added
C = solution concentration of phosphate
V = volume of solution
\ = adsorption capacity for phosphate in region I of
i(Tnmai; the isothenn>
Abj » change in adsorption maximum for region I
bit, brTT = adsorption capacities for phosphate in regions II
11 111 and III.
Ktt, Kttt = constants'related to energies of adsorption in regions
*1 111 TT TTT
From previous work, the authors had shown that adsorption in regions II and
III was essentially complete after 17 hours. By measuring changes in the
adsorption maximum bj in region I (in a separate experiment by maintaining
solution concentrations below 0.16 yg P/ml) as a function of time, a plot of
bI (= bI(initial) + abl) versus time allpwed the authors to compute.C (by
numerical methods) at any time t.
It is not surprising that the authors obtain good fits to their time
-dependent data since the constants bn, bin, Kit-, Km, and bi(in.jtial)
used in the model are estimated from statistical "fits" to Langmuir plots of
the adsorption data. The quantity C is therefore merely a back-calculation
using the same data. In addition, this expression gives no kinetic informa-
tion; i.e., no rate constants were included in the expression. It seems
likely that this model has little value in terms of predicting the type and
magnitude of phosphate adsorption mechanisms.
A simple first-order rate expression was used by Chen et al. (1973a) to
determine rate constants for adsorption of phosphate by a-AKO, and kaolin-
ite. Their rate law
[6-35]
where
II and III.
f ¦ "Kobs
[6-36]
122
-------
where, k0bs a observed rate constant,/ (?) = solution concentration of phos-
phate, was limited to the slow disappearance of phosphate from solution which
occurred for times greater than two days. A new mineral pihase was found by
electron microscopy which contained AP+ and phosphate. In addition, Kgbs
Increased with decreasing pH, which indicated that the observed slow reaction
was a result of dissolution of the mineral structures with subsequent pre-
cipitation of the aluminum phosphate mineral. Values for Kobs are presented
in Table 6-8. Enfield et al. (1976) compared the ability of five functions
to describe the kinetics of phosphate sorption during steady water flow 1n
packed soil columns.
The kinetic functions tested were as follows:
1). A first-order Eq. (6-37) using a linear adsorption isotherm previous-
ly used by Lapidus and Amundson, (1952),
ff - o(kS-C) [6-37]
where, S = amount phosphate adsorbed, C ° solution phosphate concentration,
a = adsorption rate coefficient of phosphate,, and k = linear adsorption par-
tition coefficient.
This equation assumes that the a 1s Independent of S and that k is a
single-valued constant descriptive of a linear relation between S and C.
2). Later workers (Hornsby and Davidson, 1975) used the function
|| » g(mCn - S) [6-38]
where, 8, and m are constants analogous to those In Eq. (6-37), and n is a
constant which allows for non-11near1ty between S and C.
3). An emperical function formulated by Enfield (1975) was given as
|f = aCbSd [6-39]
where, a, b, d are constants.
The last two of the five functions were inserted into a model in which
the rate of Increase of phosphate 1n a soil particle (SaVg) was limited to
diffusion of the phosphate through the spherical soil particle (Skopp and
Warrick, 1974),
Sava e p(0 - £ 4 e*P f-KjVt/r2) [6-40]
avg / j-1 j*
where, r = radius of the soil particle, k = diffusion coefficient of phos-
phate through the particle, F(C) = adsorption function relating S and C, and
Savg = average phosphate concentration In the-soil particle.
1,23
-------
Table 6-8. Observed rate constants for the disappearance of phosphate
from solutions in the presence of kaolinite and a - A1?D,
at 25"C. 1 J
pH of Kobs (dai'"1)
suspension Kaolinite o - Al^O^
3.5
0.0560
0.0240
4.3
—
0.0219
4.5
0.0224
—
5.3
0.0110
—
6.0
—
0.0071
6.2
0.0030
—
124
-------
Initial phosphate 1n the particle was assumed to be..zero and concentra-
tion of phosphate at the surface of the particle is constant.
Both Freundlich and Langmuir-type functions were used for F(C); that is,
the Freundlich equation
4). F(C) = a^C^ [6-41]
where a, and bj are constants, and the Langmuir equation
5). F(C) = ma| » kC [6-42]
where, Sma*amount of phosphate required to complete a monomolecular- on
solid soil surfaces,It = a constant related to the binding energy of phos-
phate to the solid.surfaces.
Phosphate adsorption kinetic data was obtained'from twenty-five.soils;'
and regression coefficients .were obtained for each of the models presented
above. Using these regression coefficients 1n the 1ntegrated rate expres-
sions, the authors compared calculated and observed amounts of phosphate
adsorbed at each measurement time. These correlations showed that the ex-
pressions using Eq. (6-40.) predicted the experimental data 1n one more con-
sistently than the other expressions.
Attempts at correlating the.regression coefficients obtained from the
above treatments with soil chemical and physical properties were unsuccessful.
Single and multiple regressions analyses were used.
Overman and Chu (1977a, b, and c) presented a kinetic model derived from
a reaction sequence
K k
P + Ssi&A.-^F + S. [6-44]
d
where, P = concentration of phosphate.in solution, S c concentration of ad-
sorptive sites 1n the. soil, A = concentration of adsorbed phosphate, F - con-
centration of fixed phosphate, ka = rate coefficient for adsorption, k
-------
phosphate adsorption, kr = as defined above, Ps = steady-state solution con-
k. + k
central on of phosphate, and K = —r
When corrections were made for solution pH (which affected the distribu-
tion of phosphate species), the rate expressions closely described the ad-
sorption reaction for Lakeland fine sand. Since only one soil was used in
that study, correlation with soil chemical properties was not made.
The reaction scheme upon which the study was based is similar to the one
outlined by Chen et al. (1973) in which the phosphate in solution comes to a
rapid equilibrium and subsequently undergoes a slow reaction to a precipitat-
ed phosphate compound.
A semi-empirical approach to the kinetics of phosphate sorption-desorp-
tion was outlined by Barrow and Shaw (1975). By considering a phosphate-soil
system which contained three compartments A, B, and C, and allowing them to
react according to
A?± Br^C,
they derived an expression which accounted for 99% of the variation in solu-
tion phosphate concentrations for Australian soils.
According to their derivation, the rate of phosphate transfer from B to
C is given by
$r=k(l-a)n [6-46]
where, a = proportion of phosphate transferred from B to C, n = a constant,
k = reaction rate, and t = time.
Integration and simplification of Eq. (6-46) gave
1 - a = (kt/b-j )~bl [6-47]
where, b^ = l/(n - 1), and (n - 1) kt >> 1.
The relationship between Compartments A and B had been found previously
(.Barrow, 1973) to follow the Freundlich equation
where the terms have meanings as described for Eq. (6-41). Temperature
effects on the rate of reactions were described by the Arrhenius equation
K = Ae"E/RT [6-49]
126
-------
where, k = rate constant* A <= frequency factor, E = activation energy associ-
ated with the reaction where the rate 1s described by k, and R,T = gas con-
stant and temperature.
Combination of Eqs. (6-47), (6-48), and (6-49) and simplification yields,
lnx^ ° K + B] InP - Bg lnt + Bj/T + ... [6-50]
where. K = (l/b2) In (m/a) - (l^/bg) In (Vbi), Bi » l/b2, B2 = bi/b*.
B3 = b-j (E/b2)R, and m = proportionality constant 1f the amount of phosphate
initially adsorbed was proportional to the phosphate added, and P = concentra-
tion of phosphate added to the soil. It 1s of Interest to consider that a,
b2, b|, mi and E are all parameters which have values -determined by a parti-
cular set of properties associated with, a given soli. The values of K and
B3 could thus be calculated from a suitable set of measurements* Unfortunate-
ly* Eq. (6-50) was used only as a regression equation in the author's studies.
In addition to.the lack of computation of the regression parameters from in-
dependent measurements, the rate constant appears to describe only the adsorp-
tion reaction rather than desorptlon. The equation was successful, however,
1n describing the effects of time, temperature, and added phosphate upon the
phosphate remaining in solution. Results obtained from several soils are
listed in Table 6-9. Of the models reviewed, the one proposed by Barrow and
Shaw appears to be the most satisfactory in describing phosphate sorption.
Their approach encompasses several experimental variables such as 1) Incuba-
tion times of addedphosphate with the soil, 2) temperature of incubation,
and 3) phosphate already present in the soil in addition to the times during
which adsorption and desorption occur.
MECHANISMS OF PHOSPHATE SORPTION
The failure of various types of single-site adsorption equations (i.e.,
Langmulr) to describe phosphate retention by various soil and soil components
has been generally.assumed to arise from the involvement of more than one
mechanism and/or adsorption site (Muljadi et al ., 1966; Syers et al., 1973;
Rajan et al., 1974). The complex, nature of whole soils has led to the use of
relatively simple systems such as the "pure" hydrous oxides and oxides of
aluminum and iron and silicate clay minerals to model the sorption process
of soils. Consequently, numerous investigators have tried to elucidate the
mechanisms involved in.phosphate sorption by hydrous metal oxides and sili-
cate clay minerals (Chakravarti and Talibudeen 1962; Muljadi et al., 1966;
Parf.itt et al., 1977; Kingston et al., 1972; Chen et al., 1973b; Rajan, 1975).
The terms adsorption, desorptlon, "sorption," and precipitation used 1n
discussing reaction mechanisms of phosphate and soil components are often
times used interchangeably but should be delineated as follows: A sorption
reaction involves the removal of phosphate from solution by its concentration
in a solid phase. This may be physical sorption, which 1s reversible and
results in a small decrease 1n energy; or it may be chemisorption. which is
partly or completely irreversible and results in a large decrease in energy.
Precipitation is the renoval of two or more .opponents from a, solution by
the^r mutual combination Into a new solid-phase compound. As stated earlier
127
-------
Table 6-9. Values obtained when Eq. (3-50)* was fitted to the changes in concentration of phosphate
when soils were incubated at a range of temperatures.
Equivalent values of
Proportion No. Coefficients of Eq. (3-50) primary coefficients
Soil no. of variation of
acc. for .obs. K B-j ^ b2 E, cal/mole
1
0.992
12
-36.4
2.51
0.676
5465
0.269
0.391
16070
4
0.985
12
-41.3
2.69
0.655
6610
0.243
0.371
20060
5
0.997
12
-37.1
2.45
0.687
5940
0.280
0.407
17160
6
0.987
48
-42.2
2.85
0.704
6673
0.247
0.351
18820
7
0.986
12
-34.3
2.52
0.647
5463
0.270
0.397
16780
9
0.982
12
-39.2
2.55
0.872
7105
0.342
0.342
16190
11
0.994
12
-39.6
2.22
0.742
7078
0.273
0.367
18940
13
0.990
84
-35.4
2.45
0.600
65$1
'0.245
0.408
21680
16
0.990
11
-32.4
2.93
0.604
5556
0.206
0.340
18290
*Eq. (3-50): In Xj = K + In P - B? In t + Bo/T where X] is the solution concentration of phosphate
is the concentration of phosphate added, t is time in days and T°K is the temperature.
-------
there is a fine line between precipitation and chemisorption and this has
been discussed in the literature (Wild, 1950; Hsu, 1964; Lersen, 1967).
The term chemica1 sorption wi11 be used to Include both adsorption of
phosphate through surface ligand exchange and adsorption by incorporation of
phosphate into the clay structure. Research to elucidate the mechanisms of
phosphate retention by soils 1s hindered by the complex nature of the many
different soil components, therefore much of the work has been performed on
individual clay minerals, metal oxides and hydroxides. The exact physical
and chemical characteristics of naturally occurring hydrous oxides of Fe and
A1 1s still being researched and presents some problems 1n the interpretation
of synthetically prepared materials.
Iron and Aluminum Oxides
Many studies have shown the removal of orthophosphate from solution by,
solid A1 and Fe hydrous oxides (Wild, 1950). The amount of phosphate sorbed
1n these reactions varies with the temperature, the time of reaction, and the
phosphate concentration and pH of the solution. An important electrochemical
property of these oxides is the influence of the solution pH on their surface
charge. In acid and neutral solutions the oxides carry a net positive charge
with.positive and neutral sites on their Surface. Recent studies of surface
charge and ligand exchange.(Rajan et al.,1974; Rajan, 1976) at constant pH,
using hydrous alumina, have indicated that monovalent phosphate is adsorbed
on positive sites displacing water that wfis coordinated to the oxide surface,
with neutralization of the positive charge Eq. (6-51),
OH, + OH9PO»
/ 2 v / 2 4
Al + H9P0" 5= AT + H;,0 [6-51]
\ \
0H2 OH^
Hydrous aluminum oxide has a structure in which aluminum atoms are link-
ed by hydroxide or oxide bridges (Hemand Roberson, 1967; Hsu, 1968).
OH 0
/ \ / \
Al Al Al AT [6-52]
\ / \ /
OH 0
hydroxide oxide
At the surface of the polymeric structure the coordinate positions of the
terminal atoms are occupied by aquo AI-H2O, and hydroxo Al-OH groups. The
relative proportion of the aquo and hydroxo groups 1s determined by the sus-
pension pH and in turn determines the surface charge:
129
-------
H,0 + H,0 ° OH "
/ V / v /
A1 A1 . 11 > A1 [6-53]
\ A +H+ \ >+H+ \
H20 OH n OH
(Parks, 1965). Specific adsorption of phosphate can occur by ligand exchange
with aquo, hydroxo, or ol groups. In acid solution the reactivity of these
groups to ligand exchange is in the order aquo >. hydroxo > ol (Thomas and
Kremer, 1935; Graham and Thomas, 1947). Ligand exchange of phosphate with
aquo groups would add negative charge to the surface but would not increase
the concentration of the hydroxl ions in the solution (Eq. 6-51). In con-
trast the exchange of phosphate with hydroxo groups would not affect the sur-
face charge, but would release equivalent amounts of hydroxyl ions into the
solution (Eq. 6-54).
0H? ° 0H?
/ 2 ^ / 2
A1 + H?P0. r—* A1 + OH [6-54]
\ \
OH GHsPOa
When the adsorption sites on the surface are saturated the hydrous oxide
carries no net change. Additional adsorption evidently occurs by the disrup-
tion of hydrous oxide polymers into smaller units with a comcomintant in-
crease in adsorption sites. Adsorption of phosphate on this new surface has
been found to make the surface negative (Rajan et al., 1974).
Several studies have indicated that short-range order (amorphous)
hydrous ferric oxide (Fe gel) like their aluminum analogs play an important
role in the sorption of inorganic phosphate by soils (Williams et al., 1958;
Saunders, 1965; Syers et al., 1977) and sediments (Mortimer, 1941; Syers et
al., 1973).
Much of the indirect experimental evidence dealing with the fixation of
phosphate by iron oxides supports the idea of coordination of Fe3+ to phos-
phate ions (Atkinson et al., 1972; Hingston et al., 1967). The initial re-
action of phosphate with hydrous ox-ides of iron, like their aluminum counter-
parts, can be described by Eq. (6-55) and (6-56) depending on the degree of
protonation of single co-ordinated-OH groups.
Fe— 0H9 + Fe-H9p0,
p&h — X, tH*0 [6-55]
Fe-OH Fe-OH
X + h2po" X + 0H" t6"563
Fe-OH Fe-^PO,
2 4
130
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Russel et al. (1974) and Parfitt et'dT; (1975) have demonstrated that in
Fe gel samples, dried prior to P sorption studies, the mechanism of retention
was the formation of a binuclear co-ordinated complex at the surface of the
gel. Other workers (Kyden et al1977) have made. this, same postulate and
envision a condensation reaction to proceed as shown in Eq. (6-57),
Aluminum Silicates
The principal types of crystalline aluminum silicates are kaolinitio
(1:1) and montmorlllonitic (2:1) clays. It has been known for some time that
there are two principle types of reactions Involved in phosphate retention by
aluminum silicates. At low concentrations (<0.3 x 10"3m) of phosphate,
which most likely corresponds to less than full coverage of the fast reaction
sites, phosphate is adsorbed by these clays on aluminum atoms situated at the
edge face of crystals (Mii.ljadl. et al., 1966; Rajan and Fox, 1975). At higher
phosphate concentrations-exceeding the complete coverage of fast reaction
sites there is evidence that sorption by displacing clay structural silicate
occurs (Low and Black, 1947¦> and 1950; Refenberg and Buckwold, 1954; Rajan,
1975). The reaction mechanisms for sorption by clay minerals are probably
similar to those for sorption by oxyhydroxlde compounds of Feand Al.
Miscellaneous Soil Components
Calcium carbonate may be present 1n alkaline and some neutral soils and
subsequently may influence the sorption of phosphate In these soils. Litera-
ture values for the sorption capacity.of calcium, carbonate are between that
of crystalline Clay minerals and hydrous oxides of iron and aluminum (Hol-
ford, 1974; Kuo and Lotse, 1972). Phosphate retention on calcium carbonate
is Initially a rapid mono-layer sorption and this may be followed by precipi-
tation of CaHPOa at higher phosphate concentrations. (Cole et al., 1953;
Griffin and Jurlnak, 1973).
THERMODYNAMICS OF PHOSPHATE SORPTION PROCESSES
Several authors have used thermodynamic treatments to assist in char-
acterizing phosphate sorption. Two thermodynamic quantities discussed have
been the enthalpy of adsorption and the free energy change upon adsorption of
the phosphate entity. Eath of these quantities can be obtained for certain
well defined systems and have important restrictions placed upon them in the
derivations of the,1r .associated relationships. The following treatment was
adapted from Denbigh 0971).
Consider a vessel which contains a solid adsorbent, aqueous solution of
H2PO4, and supporting inert electrolyte. The content of water is such that
its mole fraction 1s constant throughout any adsorption process. The thermo-
dynamic system will consist only of the phosphate species, associated ca-
tions, and the adsorbent with its associated anions. The process under
131
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consideration is the reversible transfer of the phosphate species from solu-
tion to the solid phase. At equilibrium,
2 = 0 [6-58j
where, = stoichiometric coefficient, = chemical potential of species i.
The chemical potential wi is defined as
"here " rePre"
sents a partial molar quantity of the species in (6-60). The same^assump-
tions apply to the use of (6-63) as in the use of (6-61). H° and H must be
132
-------
known for each respective species. Low and Slack used the van't Hoff ex-
pression to compute AH* for the adsorption of phosphate by.kaol1n1te. The
value of calculating such a thermodynamic property from this type of system
has been useful only on a relative basis. The observation that phosphate
sorption increases with temperature has been explained by several authors as
a result of positive &H° (endothermic) values (Low and Black, 1950; Haseman
et a!., 1950). However, other authors (Barrow and Shaw, 1975) have noted
that less phosphate is adsorbed at higher temperatures (at equal solution
concentrations). Differences in these observations would appear to result
from non-equilibrium conditions at the time of measurement and a change in
the rate of sorption-desorption reactions with temperature rather than the
occurrence of an endothermic adsorption process.
In addition to this limitation, (6-63) applies only to reversible pro-
cesses. Lack of proof of reversibility 1s conmon to all studies reviewed.
This review has focused on the quantification of the inorganic phosphate
sorption-desorption processes 1n soil-water systems. There appears to be a
general agreement in the literature that the disappearance of phosphate from
soil solution results from a fast Initial sorption reaction followed by a
much slower transformation of phosphate to crystalline precipitates. The
mechanisms of these transformations have not been elucidated to date.
Kinetics of the transformations have only been determined at a phenomenologi-
cal level rather than from a mechnlstlc process-oriented standpoint. Hence,
an important part of the information required for determining a phosphate
partition function is absent.
The following conclusions can be drawn based on our review of the phos-
phate sorption literature.
1. A universal partition function cannot be developed for soils using
literature data. Variations 1n measurement of the "active" Fe and Al,
and time-dependence of phosphate sorption appear to be the two most
significant parameters.in a phosphate partition function. These param-
eters have not been reported adequately in the literature for use 1n a
partition function.
2. "Active" Fe and Al appear to be measured quantitatively by oxalate
extraction rather than by citrate-di thionite-bicarbonate extraction.
Crystallinlty of Fe and Al oxyhydroxides appears to be a dominant factor
determining phosphate sorption.
3. Time-dependent disappearance of phosphate during sorption and reappear-
ance during desorption has not been, fully explained and has been modeled
successfully by the procedure of Barrow end Shaw (1975).
4. A broad range of Langmuir sorption, parameters, was,found, for phosphate
sorption by soils and other solid sorbents. Based on a limited amount
of data, the sorption parameters;were found to be significantly corre-
lated with oxalate-extractable Fe and Al.
133
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5. Lack of uniformity in experimental methods used in determining the
Langmuir sorption parameters was' noted. Development of standardized
methodology, (protocols) for this-purpose appears essential fo.r-quanti-
fication of appropriate sorption parameters.
Tie following recommendations are made based on this review:
1. Further testing of phosphate sorption models is required to determine
the most suitable sorption parameter.
2. Standardized methodology (protocols needs to be developed for measure-
ment of sorption parameters, "active" species involved in phosphate
sorption, and the time-dependence of sorption and desorption.
3. Quantification of a "crystal!inity" index for Fe and A1 oxyhydroxides
in soils is essential in describing phosphate sorption.
4. The final result must be a partition function which describes the rela-
tive concentrations of phosphate in solid and solution phases. The
function should include the variables of Fe and A1 content of the soil
(and any other chemical properties that might be required), times of the
sorption-desorption processes, and the suitable sorption parameters.
REFERENCES FOR SECTION 6
Adamson, A. W. 1976. Physical Chemistry of Surfaces. John Wiley and Sons,
NY. Third edition. Chapter 14.
Aiba, S., and H. Ohtake. 1977. Simulation of PO4-P balance in a shallow
and polluted river. Water Res. 11:159-164.
Alston, A. M., and K. W. Chin. 1974. Rock phosphate and superphosphate as
sources of phosphorus for subterranean clover on an acid sandy soil.
Aust. J. Exp. Agric. Anim. Husb. 14:358-361.
Amer, F., D. R. Bouldin, C. A. Black, and F. R. Duke. 1955. Characteriza-
tion of soil phosphorus by anion exchange resin adsorption and P32_
equilibration. Plant Soil 6:391-408.
Arambarri, P., and 0. Talibudeen. 1959. Factors influencing the iso-
topically exchangeable phosphate in soils. Plant Soil 11:343-354.
Atkinson-, R. J., F. J. Hingston, A. M. Posner, and J. P. Quirk. 1970. Elo-
vich equation reactions, at solid-liquid interfaces. Nature 226:148-
149.
Atkinson, R. J., P. M. Posner, and J. P. Quirk. 1972. Kinetics of iso-
topic exchange of phosphate at the «-Fe00H (goethite)-aqueous solution
interface. J. Inorg. Nucl. Chem. 34:2201-2211.
32 45
Avnimelech, Y. 1968. Analysis of P and Ca Exchange Between Hydroxy-
apatite and its Equilibrium Solution. Israel J. Chem. 6:375-385.
134
-------
Bache, B. W. 1964. 'Aluminum and iron phosphate studies relating to soils
11. Reactions between phosphate and hydrous oxides, j. Soil Sci.
15:110-116.
Bache, B. W., and E. G. Williams. 1971. A phosphate sorption index of
soils. J. Soil Sci. .22:289-301.
Ballaux, J. C., and 0. E. Peaslee. 1975. Relationships between sorption
and desorption of phosphorus by soils. Soil Sci. Soc. Am. Proc.
39:275-278.
Barber, S. A. 1977. Application of Phosphate Fertilizers: Methods, Rates
and Time of Application in Relation to the Phosphorus Status of Soils.
Phosphorus Agric. 70:109-115.
Barone, J. P., and G. H. Nancollas. 1977. The seeded growth Of calcium
phosphates: The effect of soil/solution ratio in controlling the
nature of the growth phase. J. Colloid Interface Sci. 62:421-431.
Barrow, N. J. 1972. Influence of solution concentration of calcium.on
the adsorption of phosphate, sulfate, and molybdate by soils. Soil
Sc1. 113:175-180.
Barrow, N. J. 1973. Relationship between a soil's ability to adsorb
phosphate and the residual effectiveness of superphosphate. Aust.
0. Soil Res. 11:57-63.
Barrow, N. J. 1974. On the displacement of adsorbed anions from soil:
1. Displacement of moTybdate by phosphate and by hydroxide. Soil
Sc1. 116:423-431.
Barrow, N. J. 1974. On the displacement of adsorbed anions from soil:
2. Displacement of phosphate.by arsenate. Soil Sc1. 117:28-33.
Barrow, N. J. 1974. The slow reactions between soil and anions. 1.
Effects of time, temperature, and water content of a soil on the
decrease in effectiveness of phosphate for plant growth. Soil Sc1.
118:380-386.
Barrow, N. 0. 1974. Effect of previous additions of phosphate on phos-
phate adsorption by soils. Soil Sc1. 118:82-89.
Barrow, N. J. 1975. Chemical form of inorganic phosphate in sheep faeces.
Aust. J. Soil Res. 13:63-67.
Barrow, N. 0. .1975. The response to phosphate of two annua1 pasture
species. 1. Effect of the soil's ability to adsorb phosphate on
comparative phosphate..requirement; Aust. J. Agric. Res. 26:137-143.
Barrow, N.. J. 1977. Phosphorus uptake and utilization by tree seedlings.
Aust. J. Bot. 25:571-584.
135
-------
Barrow, N. J., P. G. Ozanne, and T. C. Shaw. 1967. Nutrient potential and
capacity. 1. .The concepts of nutrient potential and capacity and
their application to soil potassium and phosphorus. Aust. J. Agric.
16:61-76.
Barrow, N. J., and T. C. Shaw. 1974. Factors affecting the long-term
effectiveness of phosphate and molybdate fertilizers. Commun. Soil
Sci. Plant Anal. 5:355-364.
Barrow, N. J., and T. C. Shaw. 1975. The slow reactions between soil and
anions: 2. Effect of time and temperature on the decrease in phos-
phate concentration in the soil solution. Soil Sci. 119:167-177.
Barrow, N. J., and T. C. Shaw. 1975. The slow reactions between soil and
anions. 3. The effects of time and temperature on the decrease in
isotopically exchangeable phosphate. Soil Sci. 119:190-197.
Barrow, N. J., and T. C. Shaw. 1975. The slow reactions between soil and
anions. 5. Effects of period of prior contact on the desorption
of phosphate from soils. Soil Sci. 119:311-320.
Barrow, N. J., and T. C. Shaw. 1976. Sodium bicarbonate as an extractant
for soil phosphate. 1. Separation of the factors affecting the
amount of phosphate displaced from soil from those affecting secondary
adsorption. Geoderma 16:91-107.
Barrow, N. J., and T. C. Shaw. 1976. Sodium bicarbonate as an extractant
for soil phosphate. 2. Effect of varying the conditions of extrac-
tion on the amount of phosphate initially displaced and on the
secondary adsorption. Geoderma 16:109-123.
Barrow, N. J., and T. C. Shaw. 1976. Sodium bicarbonate as an extractant
for soil phosphate. 111. Effects of the buffering capacity of a
soil for phosphate. Geoderma 16:273-283.
Barrow, N. J., and T. C. Shaw. 1977. Factors affecting the amount of
phosphate extracted from soil by anion exchange resin. Geoderma
18:309-323.
Barrow, N-. 0., and T. C. Shaw. 1977. The slow reactions between soil and
anions: 6. Effect of time and temperature of contact on fluoride.
Soil Sci. 124:265-278.
Beckett, P. H. T., and R.- E. White. 1964. Studies on the phosphate
potentials'of soils. III. The pool of Labile inorganic phosphate.
Plant Soil 21:253-257.
Beek, J., F. A. M. de Haan, and W. H. van Riemsdijk. 1977. Phosphates in
soils treated with sewage water: 1. General information on sewage
farm, soil, and treatment results. J. Environ, Qua!. 6:4-7.
136
-------
Beek, J., F. A. M. de Haan, and W. H. van Riemsdijk. 1977. Phosphates in
soils treated with sewage water: 11. Fractionation of accumulated
phosphates. J. Environ. Qtial. 6:7-12.
Bhavnagary, H. M., J. S. Vemigopal, and S. K. Majumder. 1977. Preparation
of trlcalcium phosphate by hydrolysis of dicalclum phosphate with
calcium hydroxide. J. Appl. Chem. Blotechnol. 27:393-398.
Biddappa, C. C. 1976. Phosphorus sorption and desorptlon pattern in
four rice soils of Orissa. Madras Agric. J. 63:156-159.
Biddappa, C. C., and S. Patnaik. 1.977. The. correlation of nitrogen and
phosphorus soil tests with response of paddy through modified
Mitscherlich-Bray equation. Mysore J. Agric. Sci. 11:28-33.
Bjerrum, N. 1 i)'t9. "Selected papers," pp. 245-248. Munksgaard, Copenhagen.
Blanchar, R. W., and D. C. Riego. 1977. Pyro- and tripoly-phosphate con-
tents of sediments. Water A1r Soil Pollut. 7:27-31.
Bowden, J. W., M. D. A. Bolland, A.-M. Posner, and 0. P. Quirk. 1973.
Generalized model for anion and cation.adsorption fit oxide surfaces.
Nature Phys. Sci. 245:81-83.
Bowden, J. W., A. M. Posner, and J. P. Quirk. 1973. A model for ion
adsorption on variables charge surfaces. Int. Congr. Soil Sci. Trans.
10th (Moscow, Russia) 11:29-34.
Bowden, J. W., A. M. Posner, and J. P. Quirk. 1977. Ionic adsorption on
variable charge mineral surfaces. Theoretical-charge development and
titration curves. Austr. J. Soil Res. 15:121-136.
Boyd, 6. E., A. W. Adamson, and L. S. Myers, Jr. 1947. The exchange
adsorption of ions from aqueous solutions by organic zeolites: l.L
Kinetics. J. Am.. Chem. Soc, 69:2836-2848.
Brewster, J. ..A-' N- Gancheva., andL P. H. Nye. 1975., The determination
of desorption isotherms for soil phosphate using low volumes of
solution and an anion exchange resin. 0. Soil, Sci. 26:264-377.
Broyer, T. C., C. M. Johnson, and R. P. Huston. 1972. Selenium and nutri-
tion of Astragalus: 11. Ionic sorption interactions among selenium,
phosphate, and the macro- and micronutrient cations. Plant Soil
36:651-669.
Burnbam, C. P. 1973. Extraction JiJethods for aluminum and iron in, relation
to phosphate adsorption. Conntun; Soil SC1. Plant Anal. 4:9-16.
Cabrera, F., L. Madrid, and f. DeArambarri. 1977. Adsorption of phosphate
by various oxides.: theoretical treatment of the adsorption envelope.
J. Soil Sci. 28:306-313.
137
-------
Calvert, D. V. 1975. Nitrate, phosphate, arid potassium movement into
drainage lines under three soil management systems. J. Environ.
Qual. 4:183-186.
Chakravarti, S. N., and 0. Talibudeen. 1961. Phosphate interaction with
clay minerals. Soil Sci. 92:232-242.
Chen, Y. S. R., J. N. Butler, and W. Stumm. 1973a. Kinetic study of
phosphate reaction with aluminum oxide and kaolinite. Environ. Sci.
andTechnol. 7:327-332.
Cho, C. M., J. Strong, and G. J. Racz. 1970. Convective transport of
orthophosphate (P-31 and P-32) in several Manitoba soils. Can. J.
Soil Sci. 50:303-315.
Cloos, P., A. Herbillon, and J. Echeverria. 1968. Allophane-like syn-
thetic silico-aluminas: Phosphate adsorption and availability.
Int. Congr. Soil Sci. Trans. 9th (Adelaide, Aust.) 11:733-743.
Cole, C. V., S. R. 01 sen, and C. 0. Scott. 1953. The nature of phosphate
sorption by calcium carbonate. Soil Sci. Soc. Am. Proc. 17:352-356.
Cooke, I. J. 1966'. A kinetic approach to the description of soil phos-
phate status. J. Soil Sci. 17:56-64.
Cooke, I. J., and J. Hi slop. 1963. Use of anion-exchange resin for the
assessment of available soil phosphate. Soil Sci. 96:308-312.
Dalai, R. C. 1974. Desorption of soil phosphate by anion-exchange resin.
Commun. Soil Sci. Plant Anal. 5:531-538.
Dalai, R. C., and E. G. Hallsworth. 1977. Measurement of isotopic ex-
changeable soil phosphorus and interrelationship among parameters
of quality, intensity, and capacity factors. Soil Sci. Soc. Am.
J. 41:81-86.
Dankiewicz, J., and J. Klimek. 1978. Solid solutions of CaS04-2H20 with
a high degree of isomorphic substitution of phosphates into the gypsum
lattice. Pol. J. Chem. 52:485-491.
Daughtrey, Z. Q., J. W. Gilliam, and E. J. Kamprath. 1973. Phosphorus
supply characteristics of acid organic soils as measured by desorp-
tion -and mineralization. Soil Sci. 115:18-24.
Denbigh-, 1971. The principles of chemical equilibrium. Cambridge
Univ. Press. Chapter 10.
Dick, M. A., and M. A. Tabatabai. 1977. An alkaline oxidation method for
determination of total phosphorus in soils. Soil Sci. Soc. Am. J.
41:511-514.
138
-------
Donigan,. A. S., Jr., D. C.,Beyerlein, H. H. Davis, Jr., and N. H. Crawford.
1977. Agricultural runoff management (ARM) model version II: Re-
finement and testing. Environmental Protection Agency Report
No. EPA-600/3-77-098.
During, C. 1968. Equilibrium concentrations of inorganic phosphate and
phosphate sorption properties in soils under permanent pasture: Some
practical applications. Int. Congr. Soil Set. Trans. 9th (Adelaide,
Aust.) 11:281-292.
Dyanand, S., M. B. Kamath, and N. N. Goswami. 1976. Effect of lime and
phosphate on the uptake and utilization of phosphorus by rice in
acid laterlte soils. 0. Nucl. Agric. Biol. 5:61-64.
Edzwald, J. K. 1977. Phosphorus 1n aquatic systems: the role of the
sediments. Adv. Environ. Sci. Technol. 8:183-214.
Edzwald, J. K., D. C. Toenslng, M. C-Y Leung. 1976. Phosphate adsorption
reactions with soil, clay minerals. Environ. Set. Technol. 10:
485-490.
El-Nennah, M, l^TS-. Phosphate .adsorption by War., Mg- and Ca-| sodium
magnesium, calcium, saturated soil clays. Z. Pflanzenemahr
Bodenkd 1:33-37.
El-Nennah, M., F. M. Abdou, and M. A. Massoud. 1977. The stability of
sparingly soluble phosphates 1n alkaline soils. Phosphorus Agric.
69:29-34.
Enfield, C. G., and B. E. Bledsoe. 1975. Fate of wastewater phosphorus
In soil. J.. Irrig. Drain. Div. Amer. Soc. Civil Eng; 101:145-155.
Enfield, C, G., C. C.Harlin, Jr., and B. E. Bledsoe. 1976. Comparison
of five kinetic models for orthophosphate reactions in mineral soils.
Soi1 Sci. Soc. Am. j. 40 r243-248.
Ericsson. Y. 1949. Enamel-apatite solubility. Investigations into the
calcium phosphate equilibrium between enamel and saliva. Atta
Odontol. Scand. 8, Supply 3.
Evans, R. I., and J. J. Jurinak. 1976. Kinetics of phosphate release
from a desert soil. Soil Sci. 121:205-211.
Evans., T. D., and J.K. Syers. 1971. An application of autoradiography
to study the spactal distribution of 33P-rlabel led orthophosphate
added to soil crumbs. Soil Sc1. Soc. Am. Proc. 35:906-909.
Flskell, J. G» A., and; R. S. Mansel.l. 1975. Dependence of P sorption in.
a Spodosol upon P rate, contact time, and deep tillage. Soil Crop
Sci. Soc. Fla. Proc. 34:34-38.
139
-------
Fitter, A. H., and C. D. Sutton. 1-975. The use of the Freundlich isotherm
for soil phosphate sorption data. J. Soil Sci. 26:241-246.
Fokiri, A. D. 1976. Studies of the transport of iron and phosphorus in
a Podzolic clay loam soil and isotopic indicators. Soviet Soil Sci.
8:321-330.
Fordham, A. W. 1963. The measurement of chemical potential of phosphate
in soil suspensions. . Aust. J. Soil Res. 1:144-156.
Fordhajn, A. W., and U. Schwertman. 1977. Composition and reactions of
liquid manure (guile), with particular reference to phosphate: 1.
Analytical composition and reaction with poorly crystalline iron
oxide (ferrihydrite). J. Environ. Qual. 6:133-136.
Fox, R. L., and E. J. Kamprath. 1971. Adsorption and leaching of P in
acid organic soils and high organic matter sand. Soil Sci. Soc. Am.
Proc. 35:154-156.
Fox, R. L., and E. J. Kamprath. 1970. Phosphate Sorption Isotherms for
Evaluating the Phosphate Requirements of Soil. Soil Sci. Soc. Amer.
Proc. 34:902-907.
Fried, M., C. E. Hagen, J. F. Saiz Del Rio, and J. E. Legget. 1957.
Kinetics of phosphate uptake in the soil-plant system. Soil Sci.
84:427-437.
Gachon, L. 1977. The usefulness of a good level of soil phosphate
reserves. Phosphorus Agric. 70:25r30.
Galindo, G. G., C. Olguin, and E. B. Schalscha. 1972. Phosphate-sorption
capacity of clay fractions of soils derived from volcanic ash.
Geoderma 7:225-232.
Gardner, B. R., and J. P. Jones. 1973. Effects of temperature on phosphate
sorption isotherms and phosphate desorption. Commun. Soil Sci. Plant
Anal. 4:83-93.
Gastuqhe, M. C., J. J. Fripiat, and S. Sokolski. 1963. Fixation du phos-
phore par Tes hydroxydes de fer et d'aluminum amorphes et cristallises.
Pedologic XII1:155-180.
Gebhardt, H., and N. T. Coleman. 1974. Anion adsorpton by allophanic
tropical soils:. I'll-, phosphate adsorption. Soil Sci. Soc. Am. Proc.
38:263-266.
Gillman, G. P. 1973. Studies of some deep sandy soils in Cape York
peninsula North Queesland: 3'. Losses of applied phosphorus and
sulphur. Aust. J. Exp. Agr. Anim. Husb. 13:418-422.
140
-------
Glidewell.C. 1977. Intramolecular non-bonded radii: Application to
synthetic and naturally occurring beryl lates, aluminates, silicates,
germanates, phosphates, and arsenates. Inorg.. Chim.. Acta. 25:77-90.
Glinski, J., Z. Sokolowska, and J. Szczypa. 1976. Sorption of phosphorus
and calcium in artifically flocculated soils. Pol. J. Soil Scl. 9:
11-17.
Gorlach, E., K. Gorlach, and A. Compala. 1969. The effect of phosphates
on the sorption and desorption of molybdates 1n the soil. Agr1-
chimica 13:506-512.
Graham, R. P., and W. P. Thomas. 1947. Reactivity of hydrous alumina
towards acids. J. Ainer. Chem. Soc. 69:816-819.
Greenwald, I. 1942. The solubility of calcium phosphate. I. The effect
of pH and the amount of solid phase. J. Biol. Chem. 143:703-714.
Griffin, ft.-A., and J, J. Jurinaii. 1973. The Interaction of Pttdsph'atfe'
with Calcite. Soil Sci. Soc. Amer. Proc. 37:847-850.
Griffin, R. .A., and J. J. Jurinak. 1973. Test of a new model,for the
kinetics of adsorption-desorption processes. Soil Sci. Soc. Am. Proc.
37:869-872.
Griffin, K. A., and J. J. Jurinak. Kinetic of the phosphate Interaction
with calcite. Soil Sc1. Soc. Amer. Proc. 38:75-79.
Gunary, D. 1970. A new adsorption isotherm for phosphate in soil. J. Soil
'Sc1'. 21 :72-77.
Gunary, D., and C. D. Sutton. 1967. Soil factors affecting plant uptake
of phosphate. J. Soil Sci. 18:167-173.
Gupta, R. K., and T. A- Singh. 1977. Interrelationships among labile
phosphorus kinetics phosphate .potentials and fertilizer response of
rice 1n Sub-Himalayan soil. Agrochlmica 21:123-133.
Hagin, J., £. Segal.l* and Y.. Avnimglech. 1971. Fixation and availability
of added phosphorus in soils as a function of bulk movement and dif-
fusion and the rate of formation of reaction products. Technion-
Israel Institute of Technology, Fertilizer Development and Soil
Fertility Laboratory, final report.
Harrop, D., and A. J. Head. 1977. Temodynamlc properties of phosphorus
compounds. 4. The energy of combustion of tr1phenylphosphine oxide:
a test substance for the combustion calorimetry of organophosphorus
compounds. J. Chen. Thermodyn. 9:1067r\076.
Harter, R. D. 1969. Phosphorus.adsorption sites in soils. Soil Sci. Soc.
Am. Proc. 33r63Q-632.
141
-------
Harter, R. D., and B. B. Foster. 1976. Computer simulation of phosphorus
movement through soils. Soil Sci. Soc. Am. J. 40:239-242.
Baseman, J. F., E. H. Brown, and C. D. Whitt. 1950. Some reactions of
phosphate with clays and hydrous oxides of iron and aluminum. Soil
Sci. 70:257-271.
Haysom, M. B. C. 1974. Phosphate sorption characteristics of Mackay
soils. Proc. Queensl. Soc. Sugar Cane Technol. 41st:43-51.
Helyar, K. R., and D. N. Munns. 1975. Phosphate fluxes in the soil-
plant system: A computer simulation. Hilgardia 43:103-130.
Helyar, K. R., D. N. Munns, and R. 6. Buran. 1976. Adsorption of phos-
phate by gibbsite: 11. Formation of a surface complex involving
divalent cations. J. Soil Sci. 27:315-323.
Hem, J. D., and C. E. Robertson. 1967. Form and stability of aluminum
hydroxide complexes in dilute solution, U. S. Geol. Survey Water
Supply Paper, 1827-A.
Hemwell, J. B. 1957. The tole of clay minerals in phosphorus fixation.
Soil Sci. 83:101-108.
Hernando, V. 1977. The problem of phosphorus in Spanish calcareous soils.
Phosphorus Agric. 70:47-62.
Hill, W. A., H. L. Bohn, and G. V. Johnson. 1974. White phosphorus-
ammonia reaction product as a phosphatic fertilizer in alkaline and
limed acid soils. Agron. J. 66:115-117.
Hira, G. S., and N. T. Singh. 1977. Observed and predicted rates of
phosphorus diffusion in soils of varying bulk density and water con-
tent. Soil Sci. Soc. Am. J. 41:537-540.
Hingston, F. J., R. J. Atkinson, P. M. Posner, and J. P. Quirk, 1967.
Specific adsorption of anions. Nature (Lond.) 215:1459-1461.
Hingston,-F. J., A. M. Posner, and J. P. Quirk. 1971. Competitive adsorp-
tion of negatively charged ligonds on oxide surfaces. I. 5urface
Chemistry, of Oxides. Disc. Faraday Society. 52:334-342.
Holford, I. C. R. 1974. In: Fertilizers and the Environment. D.R. Leece
(Ed.<) Purt. Inct. Agri. Sci.
Holford, I. C. R. 1977. Soil properties related to phosphate buffering
in calcareous soils. Commun. Soil Sci. Plant Anal. 8:125-137.
Holford, I. C. R., and G. E. G. Mattingly. 1975. Phosphate sorption by
Jurassic oolitic limestones calcareous soils. Geoderma 13:257-264.
142
-------
Holford, I. C. R.., and 6. E. G. Mattingly. 1976. Soil phosphate adsorp-
tion and plant availability of phosphate. Plant Soil 44:377-389.
Holford, I. C, R., R. W. M. Wedderburn, and G. E. G. Mattingly. 1974. A
Langmuir two-surface equation as a model for phosphate adsorption by
soils. J. Soil Sci. 25:242-255.
Hope, G. D., and J. K. Syers. 1976. Effects of solution: soil ratio on
phosphate sorption by soils. J. Soil Sci. 27:301-306.
Hornsby, A. G., and 0. M. Davidson. 1973. Solution and adsorbed fluo-
meturon concentration distribution in a water-saturated soli:
Experimental and predicted evaluation. Soil Sci. Soc. Amer. Proc,
37:823-828.
Hsu, P. H. 1964. Adsorption of phosphate by aluminum and iron in Soils.
Soil Set. Soc. Am. Proc. 28:474-478.
Hsu, P. H. 1965. Fixation of phosphate by aluminum and Iron 1n acid soils.
Soil Sci. 99:398-402.
Hsu, P. H. 1976. Comparison of Iron(1,11) and aluminum 1n precipitation
of phosphate from, solution. Water Res. 10:903-907.
Hsu, P. H., and 0. A. Rennie. 1962. Reactions of phosphate in aluminum
systems. 1. Adsorption of phosphatp by X-ray amorphous "aluminum
hydroxide." Can. J. Soil Sci. 42:197-209.
Huang, C. P. 1977. Removal of phosphate by powdered aluminum oxide adsorp-
tion. J. Water Pollut. Control Fed. 49:1811-1817.
Huffman, E. 0. 1969. Behavior of fertilizer phosphates. Trans. Int.
Congr. Soil Sci. 9th. 2:745-754.
Huffman, E. 0. 1970. Fertilizer-soil reactions and the phosphate status
of soils. Phosphorus Agric. 24:13-23.
Humphreys, F. R., and W. I. Pritchett. 1971. Phosphorus adsorption and
movement in, some sandy forest.soils." Soil Sci. Soc. Am. Proc. 35:
495-500.
Hwang, C. P., T. H. Leckie, and P. M. Huartg. 1972. Adsorption of Inorganic
phosphorus by lake sediments. J. Water Pollut. Control Fed. 48:
2754-2760.
Irving, R. J., M. H. Abraham, 0. E. Salmon, A. Martbn, and J. Inczedy. 1977.
Thermochemical aspects of anion exchange reactions. 1. -Exchange re-
actions involving chloride, hydroxide, and orthopho&phate Ions. J.
Inorg. Nucl. Chem. 39:1433-1436.
Jain, 0. M., M. Velayutham, and R. Hasan. 1972. Changes In the dynamics of
phosphate equilibria on storing soil samples. Curr. Sci. 41:489-490.
143
-------
Jensen, H. E. 1970. Phosphate potential and phosphate capacity of soils.
Plant Soil 33:17-29.
Jensen, M. E. 1-971. Phosphate solubility in Danish soils equilibrated
with solutions of differing phosphate concentrations. J. Soil Sci.
22:261-256.
Jones, J. P., and R. L. Fox. 1977. Phosphate sorption curves as a soil
testing technique: A simplified approach. Commun. Soil Sci. Plant
Anal. 8:209-219.
John, M. K. 1972. Factors affecting the adsorption of micro-amounts of
tagged phosphorus by soils. Commun. Soil Sci. Plant Anal. 3:197-205.
Kafkafi, U., A. M. Posner, and J. P. Quirk. 1967. Desorption of phos-
phate from kaolinite. Soil Sci. Soc. Am. Proc. 31:347-353.
Khalid, R. A., W. H. Patrick, Jr., and R. D. Dalaune. 1977. Phosphorus
sorption characteristics of flooded soils. Soil Sci. Soc. Am. J.
41:305-310.
Kinjo, T., and P. F. Pratt. 1971. Nitrate adsorption: 11. In competi-
tion with chloride, sulfate, and phosphate. Soil Sci. Soc. Am.
Proc. 35:725-728.
Kittrick, J. A., and M. L. Jackson. 1957. Electron-microscope observa-
tions of the reactim of phosphate with minerals, leading to a unified
theory of phosphate fixation in soils. J. Soil Sci. 7:81-89.
Krishnappa, M., C. C. Biddappa, and B. V. Venkata Rao. 1975. A kinetic
approach in the study of phosphorus status of red sandy loam soils.
J. Indian Soc. Soil Sci. 23:47-50.
Kunishi, H. M., and A. W. Taylor. 1975. The effect of phosphate applica-
tions on the diffusion coefficients and available phosphate in an
acid soil. J. Soil Sci. 26:267-277.
Kuo, S., and E. G. Lotse. 1972. Kinetics of phosphate adsorption by
calcium carbonate and Ca-kaolinite. Soil Sci. Soc. Am. Proc. 36:
725-729.
Kuo, S., and E. G. Lotse. 1973. Kinetics of phosphate adsorption and
desorption by hematite and gibbsite. Soil Sci. 116:400-406.
Kyle, J. H., A. M. Posner, and J. P. Quirk. 1975. Kinetics of isotopic
exchange of phosphate adsorbed on gibbsite. J. Soil Sci. 26:32-43.
Laidler, K. J. 1965. Chemical Kinetics. McGraw-Hill, NY. p. 318.
144
-------
Lake, C. A., and W. G- Maclntyre. 1977. Phosphate and tripolyphosphate
adsorption by clay minerals and estuarine sediments. Virginia
Polytechnic Inst. Stat. Univ., Virginia Water Resources Res. Center.
Bull. 109.
Lance, J. C. 1977. Phosphate removal from sewage by soil columns. J.
Environ. Qual. 6:279-284.
Langmuir, I. 1918. The adsorption of gasses on plane surfaces of glass,
mica, and platinum. J. Am. Chan. Soc. 40:1361-1403.
Lapidus, L., and N. R. Amundson. 1952. Mathematics of adsorption in beds.
VI. The effect of longitudinal, diffusion, in, i«n-exchange and chro^-
matographlc columns. J, Phys. Chem. 56:984-988.
Larsen, S, 1965. The influence of calcium chloride concentrfctiin fh the
determination of Hme and phosphate potentials of soils. J. Soil Sc1.
16:275-278.
Larsen, S. 1966. The solubility of phosphate in a calcareous soil.
J. Soil .Sci. 17:121-126.
Larsen, S. 1967. Soil phosphorus. Adv. Agron. 19:151-210.
Larsen, S., and M. N. Court- 1961. Soil phosphate solubility. Nature.
189:164-165.
Larsen, S., D. Gunary, and C. 0. Sutton. 1965. The rate of Immobiliza-
tion of applied phosphate in relation to soil properties. J. Soil
Sci. 16:141-148.
Larsen, S., and A. E. Widdowson. 1964. Effect of soil/solution ratio on
determining the chemical potentials of phosphate ions in soil solu-
tions. Nature 203:942.
Leaver, J. P., and E. W. Russell. 1957. The reaction between phosphate
and phosphate-fixing soils. J. Soil Sci. 8:
Lee, G. F. 1970. "Entrophication Information Proyram," Occ. Pap. No. 1,
University of Wisconsin, Madison.
Licthtenwalner, D. C., A. L. Flenner, and N. E. Gordon. 1922. Adsorption
and replacement of plant food in colloidal oxides of Iron and
aluminum. Soil Sci. 15:3.
Lieser, Von K. H., Ph. GutUch, and I. Rosenbaum. 1945. Lebrstuhl fur
Kernchemie, Tectvnlsche Hochschule Darmstadti Radlochim. Acta. 4:216.
Lindsay, W. L., and Vlek, P. G, L. 1977. "Phosphate Minerals," In Miner-
als in Soil Environments (Ed. by J. B. Dixon and S. B. Weed), SSSA,
Madison, Wisconsin.
145
-------
Lindsay, W. L., and H. F. Stephenson. 1959. Nature of the reactions of
morocalcium phosphate monohydrate'i n soils: I. The solution that
reads .with -the soil-.- So.i.1 Sqi-v Soc,.. .Ainejv Proc.- 23;.12-18.
Logan, T. J. 1980. The role of soil and sediment chemistry in modeling
nonpoint sources of phosphorus. In Environmental Impact of Nonpoint
Source Pollution (Overcash, M.R. and Davidson, J.M., editors). Ann
Arbor Science Publishers.
Logan, T.J., and E. D. McLean. 1973. Nature of phosphorus retention and
adsorption with depth in soil columns. Soil Sci. Soc. Am. Proc.
37:351-355.
Lopez-Hernandez, D., and C. P. Burnham. 1973. Extraction methods for
aluminum and iron in relation to phosphate adsorption. Commun. Soil
Sci. Plant Anal. 4:9-15.
Lopez-Hernandez, I. D., and C. P. Burnham. 1974. The covariance of phos-
phate sorption with other soil properties in some British and tropical
soils. J. Soil Sci. 25:196-205.
Lopez-Hernandez, I. D., and C. P. Burnham. 1974. The effect of pH on phos-
phate adsorption in soils. J. Soil Sci. 25:207-215.
Lopez-Hernandez, D., and C. P. Burnham. 1974. Phosphate adsorption by
organic soils in Britain. Int. Congr. Soil Sci. Trans. 10th (Moscow,
Russia) 11:73-80.
Low, P. F., and C. A. Black. 1947. Phosphate-induced decomposition of
kaolinite. Soil Sci. Soc. Amer. Proc. 12:180-184.
Low, P. F., and C. A. Black. 1950. Reactions of phosphate with kaolinite.
Soil Sci. 70:273-290.
Luff, B. B., and R. B. Reed. 1978. Enthalpy of solution of dipotassium
orthophosphate at 25°C. J. Chem. Eng. Data 23:56-58.
Luff, B. B., and R. B. Reed. 1978. Low-temperature heat capacity and
entropy of dipotassium orthophosphate. J. Chem. Eng. Data 23:58-60.
Luff, B. B., and R. B. Reed. 1978. Standard enthalpies of formation of
monopotassiMm and dipotassium orthophosphate. J. Chem. Eng. Data
23:60-62;*'
Lung,'W.-S.y R,,:-Pv'CanaTe, and P. L". Freedman. 1976. Phosphorus models
for eutrophic lakes. Water Res. 10:1101-1114.
Machenthum, K. M. 1965. "Nitrogen and Phosphorus in Water." U. S. Dept.
of Health, Education and Welfare, Public Health Serv., Div. of Water
Supply and Pollution Control, U. S. Govt. Printing Office, Washington,
D. C.
146
-------
McAuliffe, C. D., N. S. Hall, L. A. Dean, and S. B. Hendricks. 1948. Ex-
change reactions between phosphate and, soil : hydroxy!ic surfaces of
soil minerals. Soil Sci. Soc. Am. Proc. 12:119-123.
McCallister, D. L., and T. J. Logan. 1978. Phosphate adsorption-desorp-
tion characteristics of soils and bottom sediments in the Maumee
river basin of Ohio. J. Environ. Qual. 7:87-92.
McDowell, H., T. M. Gregory, and W. E. Brown. 1977. Solubility of
Ca5(P04)3(0H) in the system Ca{0H)2-Ho-P04-H20 at 5, 15, 25, and
37°C. J. Res. Natl. Bur. Stand., Sect. A. pp. 273-281.
McLaughlin, J. R., J. C. Ryden» and Jv K. Syers., 197.7. Development, and
evaluation of a kinetic model, to describe phosphate sorption by
hydrous ferric oxide gel. Geoderma 18:295-307.
Mandal, L. N>., and S. K. Khan. 1976. Influence of different moisture
regimes oh the transformation of applied phosphate 1n rice soils 1n
its availability to rice plants. J. Indian Soc. Soil Sci. 24:3^4-381
Manning, P. 6. 1977. Moessbauer spectral studies of ferric phosphate
interaction in sediments underlying oxic lake waters. Can. Mineral
15:422-426.
Mansell, R. S., H. M. Selira, P. Kanchanasut, J.M. Davidsonr and J. G. A.
F1skelT. 1977. Experimental and simulated transport of phosphorus
through sandy soils. Water Resources Res. 13:189-194.
Marion, G. M., and K. L. Badcock. 1977. The solubilities of carbonates
and phosphates 1n calcareous soils suspensions. Soil Sci. Soc. Am.
J. 4:724-728.
Mattingly, G. E. G. 1975.. Labile phosphate in soils. Soil Sci. 119:
369-375.
Mattson, S..E. Kouteler-Andersson, IC. B. Miller, andK. Vahtrac. 1951„
Phosphate relations of soil and plant. VIII. Electrokinetics,
amphoteric behavior and Kgl. solubility relations. Lantbruks-Hogskol.
Ann. 18:128-153,
May, J., J. R., Mettenry, and J. C. Ritchie!. 1976. Phosphorus 1n the
sediments of Lake Verret-Palourde, Louisiana. J. M1ss. Acad. Sci.
21:413.
Moghimi, A., D. G. Lewis, and J. M. Oades. 1978. Release of phosphate
from calcium phosphates by rhizosphere products. Soil Biol. B1o-
chem. 10:227-281.
Moore, P. B., and A. R. Kampf. 1977. Schoonerite, a niew zinc-manganese-
iron phosphate .mineral. Am. Mineral 62 :246-249.
147
-------
Mortimer, C. H. 1941. The exchange of dissolved substances between mud
and water in lakes. J. Ecol. 29:280-329.
Muljadi, D., A. M. Posner, and J. P. Quirk. 1966. The mechanism of phos-
phate adsorption by kaolinite, gibbsite, and pseudoboehmite. 1.
The isotherms and the effect of pH on adsorption. J. Soil Sci.
17:212-228.
Munns, D. N., and R. L. Fox. 1976. The slow reactions which continue
after phosphate adsorption: Kinetics and equilibrium in some
tropical soils. Soil Sci. Soc. Am. J. 40:46-51.
Myszka, A., and M. Oanowska. 1973. Phosphorus sorption of soils at low
concentrations of the absorbate, determined by a chemical and radio-
metric method. Pol. J. Soil Sci. 6:27-35.
Nagarajah, S., A. M. Posner, and J. P. Quirk. 1970. Competitive adsorp-
tion of phosphate with polygalacturonate and other organic anions on
kaolinite and oxide surfaces. Nature 228:83-85.
Neller, J. R. 1946. Mobility of phosphate in sandy soils. Soil Sci.
Soc. Am. Proc. 11:227-230.
Novak, L. T., and D. C. Adriano. 1975. Phosphorus movement in soils:
soil-orthophosphate reaction kinetics. J. Environ. Qual. 4:261-266.
Novak, L. T., D. C. Adriano, G. A. Coulman, and D. B. Shah. 1975. Phos-
phorus movement in soils: Theoretical aspects. J. Environ. Qual.
4:107-113.
Nriagu, J. 0. 1976. Phosphate-clay mineral relations in soils and sedi-
ments. Can. J. Earth Sci. 13:717-736.
Obihara, C. H., and E. W. Russell. 1972. Specific adsorption of silicate
and phosphate by soils, 0. Soil Sci. 23:105-117.
Ohle, W.' 1953. Phosphorus as the initial factor in the development of
eutrophic waters. Vom Wasser. 20:11-23.
OJ'Sen, S. R., and F. S. Watanabe. 1957. A method to determine a phos-
phorus adsorption maximum of soils as measured by the Langmuir
isotherm.- Soil Sci. Soc. Am. Proc. 21:144-149.
Qlsen, S. R,.,. R. k. Bowman, and F. S. Watanabe. 1977. Behavior of phos-
phorus in the soil and interactions with other nutrients. Phosphorus
Agric. 31:31-46.
Olsen, S. R., R. A. Bowman, and F. S. Watanabe. 1977. Behavior of phos-
phorus in the soil and interactions with other nutrients. Phosphorus
Agric. 70:7-16.
148
-------
Owens, L. D. W. Nelson, and L. E. SorQmers. 1977. Determination of
inorganic phosphorus.in oxalate extTfects of soils. Soil Sci. Soc.
Am,,J. 41:148-149.
Overman, A. R., and R. L. Chu. 1977. A kinetic model of steady state
phosphorus fixation 1n a batch reactor--l. Effect of soil solution
ratio. Water Res. 11:771-775.
Overman, A. R., and R. L. Chu. 1977. A kinetic model of steady state
phosphorus fixation in a batch reactor—11. Effect of pH. Water
Res. 11:777-778.
Overman, A. R., and R.. L, Chu. 1977. A kinetic model;of steady/state.
phosphorus.fixation 1n batch reactor—111. Effect of solution
reaction. Water Res. 11:779—781.
Ozanne, P. G., D. J. Kirton, and T. C. Shaw. 1961. The los~s of phosphorus
from sandy soils. Aust. J. Agric. Res. 12:409-423.
Parfitt, R. L., R. J. Atkinson, and R. St. C. Smart. 1975. The mechanism
of phosphate fixation by Iron oxides. Soil Sci. Soc. Am. Proc.
39:837-841.
Parfitt, R. L. , A. R. Fraser, J. D. Russell, and V. C. Fanner. 1977. Ad-
sorption on hydrous oxides. 11. Oxalate, berwoate, and phosphate on
gibbsite. J. Soil Sci. 28:40-47.
Parfitt, R. L., A. D. Thomas, R. J. Atkinson, and R. St. C. Smart. 1974.
Adsorption of phosphate of imogolite. Clays Clay Mineral 22:455-456.
Parks, G. A. 1965. The isoelectric points.of solid oxides',"solid hy-
droxides and aqueous hydroxo compex systems. Chem Res. 65:177-198.
Patrick, W. H., Jr., and R. A. Khalid. 1974. Phosphate release and sorp-
tion by soils and sediments: effect of aerobic and anerobic condi-
tions. Science 186:53-55.-
Perrott, K. W., A. G. Langdon* and A. T. Wilson. 1974., Sorption of
phosphate by aluminum and iron(111)-hydroxy species on mica surfaces.
Geoderma 12:223-231.
Piper, C. S. 1942. Soil and Plant Analysis, pp. 192-5. Univ. Adelaide.
365 pages.
Porananond, K., and P. G. E. Searle. 1977. The effect of time of fertil-
izer-soil contact, distance of phosphate movement, and fertilizer
solubility on phosphate availability to early growth of lowland rice.
Plant Soil 46:391-404.
Pulford, I. 0., and tt. J. tluncan. 1975. The influence of pyrite oxida-
tion products on the adsorption of phosphate by coal-mine waste.
J. Soil Sci. 26:74-80.
149
-------
Rajan, S. S. S. 1973. Phosphorus adsorption characteristics of Hawaiian
s.oiTs and their relationships to equilibrium phosphorus concentrations
required for max4mim growth of millet. Plant Soil 39:51'9—532.
Rajan, S. S. S. 1975. Phosphate adsorption and the displacement of
structural silicon in an allophane clay. J. Soil Sci. 26:250-256.
Rajan, S. S. 5. 1976. Nature 262:45.
Rajan, S. S. S., and R. I. Fox. 1975. Phosphate adsorption by soils. 11.
Reactions in tropical acid soils. Soil Sci. Soc. Am. Proc. 39:846-851.
Rajan, S. S. S., K. W. Perrott. 1975. Phosphate adsorption by synthetic
amorphous aluminosilicates. J. Soil Sci. 26:257-266.
Rajan, S. S. S., K. W. Perrott, and W. M. H. Saunders. 1974. Identifica-
tion of phosphate-reactive sites of hydrous alumina from proton con-
sumption during phosphate adsorption at constant pH values. J. Soil
Sci. 25:438-447.
Rajan, S. S. S., J. H. Watkinson. 1976. Adsorption of selenite and phos-
phate on an allophane clay. Soil Sci. Soc. Am. Proc. 40:51-54.
Raupach, M. 1963. Solubility of simple aluminum compounds expected in
soils. III. Aluminum ions 1n soil solutions and aluminum phosphates
in soils. Australian J. Soil Res. 1:46-54.
Ray, S. C., and S. C. Das. 1974. Adsorption and desorption of phosphate
in clays and clay constituents in relation to pH and phosphate con-
centration in solution. 1. Clay minerals: hydrogen and aluminum
clays. Indian Agric. 18:235-247.
Ray, S. C., and S. C. Das. 1976. Adsorption and desorption of phosphate
in clays and clay constituents in relation to pH and phosphate con-
centration in solution. 11. Adsorption of phosphate in binary mix-
ture of clay minerals. Indian Agric. 20:39-42.
Rejidy, M. M. T977. Crystallization of calcium carbonate in the presence
of trace concentrations of phosphorus-containing anions. 1. Inhi-
bition by phosphate and glycerophosphate ions at pH 8.8 and 25°C.
C. Cryst. Growth 41:287-295.
Reddy, S., and Y. K. Reddy. 1977. Precipitation of manganese anmonium
phosphate from, homogeneous solution by urea hydrolysis. Indian J.
Chem. 15A:352-353.
Rhodes, E. R. 1977. Simple phosphate sorption index on some soils of
the humid tropics. Plant Soil 46:263-266.
Riemsdijk, W. H. van., F. A. Weststrate, and G. H. Bolt. 1975. Evidence
for a new aluminum phosphate phase from reaction rate of phosphate
with aluminum hydroxide. Nature 257:473-474.
150
-------
Romkens, M. J. M., and D. W. Nelson, 1974. Phosphorus relationships in
runoff from fertilized soils. J. Environ. Qual. 6:10-13.
Rothbaum, H. P., and A. 6. Rohde. 1976. Long-term leaching of nutrients
from magnesium anrnonlum phosphate at various temperatures. N.Z.J.
Exp. Agric. 4:405-413.
Russell, E. W. 1973. The sources of plant nutrients in the soil: Phos-
phate. p. 555-579. In. Soil condition and plant growth. Longman
Press, N.Y.
Russell, E. W. 1973. The sources of plant nutrients in the soil: phos-
phate fertilizers, p. 580-603. In Soil condition and plant growth;
Longman Press, N.Y.
Russell, J. D., R. L. Parfitt, P. R.. Fraser, and V. C. Farmer. 1974. Sur-
face structures of gibbslte,- goethite, and phosphated geothite,
Nature, Lond. 248:220-221.
Russell, R. 0. 1963. Experiments on Cumulative Dressings of Fertilizers
on Calcareous Soils in South-West England. 1.-Description of field
experiments and soil analysis for phosphorus residues. J. Sci.
Food Agric. 14:622-628.
Russell, R. S., J. B. Rickson, and S. N. Adams. 1954. Isotopic equilibria
between phosphates 1n'so1l and their significance in the assessment
of fertility by tracer methods. J. Soil Sci. 5:85-105.
Ryden, J. C., J. R. McLaughlin, and J. K. Syers. 1977a. Mechanisms of
phosphate sorption by soils and hydrous ferric oxide gel. J. Soil
Sci. 28:72-92.
Ryden, J. C..J.R. McLaughlin, and J. K. Syers. 1977b. Time-dependent
sorpton of phosphate by soils and hydrous ferric oxides. J. Soil
Sci. 28:585-595.
Ryden, J. C., and J. K. Syers. 1975. Rationalization of ionic strength
and cation effects on phosphate sorption by soils. J. Soil Sci.
26:395-406.
Ryden, J. C., and J. K. Syers. 1976. Calcium retention in response to
phosphate sorption by soils. Soil Sci. Soc. Am. J. 40:845-846.
Ryden, J. C., and J. K. Syers. 1977. Desorption and isotopic exchange
relationships of phosphate sorbed by soils and hydrous ferric oxide
gel. J. Soil Sci. 28:596-609.
Ryden, J. C., and J. K. Syers. 1977. Origin of the labile phosphate pool
in soils. Soil Sci. 123:353-361.
151
-------
Ryden, J. C., J. K. Syers, and R. F. Harris. 1973. Phosphorus in runoff
?nd streams. Adv. Agron. 25:1-45.
Rydeji, J. C., J. K. Syers, and J. R. McLaughlin. 1977. Effects of ionic
strength on chemisorption and potential-determining sorption of
phosphate by soi'.ls: J. So.il Sci. '28:62-71 .
Sacheti, A. K., and S. N. Saxena. 1972. Availability of some soil phos-
phate reaction products. Indian Soc. Soil Sci. J. 20:219-224.
Sadler, J. M., and J. W. B. Stewart. 1977. Labile residual fertilizer
phosphorus in Chernozemic soils. 1. Solubility and quantity-inten-
sity studies. Can. J. Soil Sci. 57:65-73.
Sahrawat, K. L. 1977. EDTA extractable phosphorus in soils as related
to available and inorganic phosphorus forms. Commun. Soil Sci. Plant
Anal. 8:281-287.
Sanyal, S. K., and D. L. Deb. 1976. Effect of reaction time and reaction
temperature on phosphorus and zinc availability in soil. J. Nucl.
Agric. Biol. 5:54-60.
Sarangamath, P. A., B. N. Shinde, and S. Patnaik. 1977. 32p tracer
studies on the methods of increasing the efficiency of citrate
soluble and insoluble phosphates for rice on acid soils. Soil Sci.
124:40-44.
Sarkar, D., M. C. Sarkar, and S. K. Ghosh. 1977. Reaction products from
fertilizer phosphorus in alluvial soils of West Bengal. Fert. News,
pp. 30-34.
Sarkar, D., M. C. Sarkar, and S. K. Ghosh. 1977. Soil-fertilizer phos-
phorus reaction products in lateritic soils of West Bengal. Fert.
Techno1, 14:43-48.
Sarkar, M. C. 1974. Effect of addition of fertilizers to soils of dif-
ferent textures on the equilibrium phosphate potential of soils.
J. Indian'Soc. Soil Sci. 22:84-85.
Saunders, W. M. H. 1965. Phosphate retention by New Zealand soils and
its relationship to free sesquioxides, organic matter, and other
soil properties. N.Z.J. Agric. Res. 8:30-57.
Sawhney, B. L. 1977, Predicting phosphate movement through soil columns.
C. Environ. Qual. 6:86-89.
Sawhney, B. L., and D. E. Hill. 1975. Phosphate sorption characteristics
of soils treated with domestic waste water. J. Environ. Qual.
4:342-346.
Shapiro, R. E., and M. -ried. 1959. Relative release and retentiveness
of soil phosphates. Soil Sci. Soc. Am. Proc. 23:195-198.
152
-------
Schwertmann, U. 1964. Differenzierung, der Eisenoxide des Bodens durch
Extraktlon mit Aramonliumpxaldt-Lpsung. I. Pfl. Ernahr. i)ung. Bodenk.
105:194-202.
Sharpley, A. N., R. W.. Tillman, and J. K. Syers. 1977. Use of laboratory
extraction data to predict losses of dissolved Inorganic phosphate
in surface runoff and tile drainage. J. Environ. Qual. 6:33-36.
Shipp, R. R., and Matelski. R. P. 1960. A microscopic determination of
apatite and a study of phosphorus in some Nebraska soil profiles. Soil
Sci. Soc. Amer. Proc. 24:450-452.
Shukla, S.. S., J. K. Syers, J. 0. H. Williams, 0. E. Armstrong, and R. F.
Harris. 1971. Sorption of inorganic phosphate by lake sediments.
Soil Sci. Soc. Am. Proc. 35:244-249.
Sil'len, L. G., and A> E. Martell. 1964. Chem. Soc. London, Spec. Publ. 17.
Sinclair, A. G. 1975. Reactions of fused calcium-magnesium phosphate
and superphosphate on a highly phosphate-fixing soil. 1. Particle
size effects. N.Z.,J. Exp. Agric. 3:105-110.
Sinclair, A. G. .1975. Reaction of fused calcium-magnesium phosphate
and superphosphate 6n a highly phosphate-fixing soil. 11. Placement
effects. N.Z.J. Exp. Agric. 3:111-116.
Singh, B. B., and M. A. tabatabai. 1977. Effects of soil properties on
phosphate sorption. Commun. Soil Sci. Plant Anal. 8:97-107.
Singh, B. B., and M. A. tabatabai. 1978. Effects of equilibrating salt
solutions on phosphates sorption by soils. Commun. Soil Sci. Plant
Anal. 7:677-688.
Singhania, R. A., P. K. Qomen, and NvN. Gosiwami. 1976- Transformation
of applied phosphorus in neutral to aTkaline.alluvial and red soils.
J. Nucl. Agric. Biol. 5:81r83.
Skopp., J., and A. W. Warfick. 1974. A two-phase model for miscible dis-
placement of reactive solutes in soils. Soil Sci. Soc. Amer. Proc.
38:545-550.
Smith, E. A., P. T. S. Wflng, and C."I. Mayfield. 1977. Effects of phos-
phorus from apatite on development of freshwater communities. J.
Fish. Res. Board Can. 34:2405-2409.
Smith, 0. M. 1970. Chemical Engineering Kinetics. McGraw-Hill, NY. Chap. 1.
Spencer, W. F. 1957. Distribution and availability of phosphates added
to a Lakeland fine sand. Soil Sci. Soc. Am. Proc. 21:141-144.
153
-------
Sree Ramulu, U. S., P. F. Pratt, and A. L. Page. 1967. Phosphorus fixa-
tion by soils in relation to extractable iron oxide and mineralogical
composition. Soil Sci. Soc. Am. Proc. 31:193-196.
Steele, K. W. 1976. Effect of added phosphorus on the availability and
forms of phosphorus present in two soils of the Manawatu-Rangitikei
sand country. N.Z. 0. of Agric. Res. 19:443-449.
Stewart, K. M., and 6. A. Rohlich. 1967. Entrophication-A Review.
Report to the State Water Control Board, California.
Stilwell, T. C., and T. G. Arscott. 1978. The relationship between fluo-
ride-titratable (reactive) soil aluminum and plant growth. Soil
Sci. 125:28-33.
Stoltenberg, N. L., and J. L. White. 1953. Selective loss of plant
nutrients by erosion. Soil Science Soc. Amer. Proc. 17:406-410.
Sturmn, W., and J. 0. Leckie. 1971. Phosphate Exchange with Sediments.
In Proceedings 5th International Conference on Water Pollution,
Perganmon, New York.
Stunri, W., and J. J. Morgan, 1970. Aquatic Chemistry, Wiley-Interscience,
New York.
Subbarao, Y. V., and R. Ellis, Jr. 1975. Reaction products of polyphos-
phates and orthophosphates with soils and influence on uptake of
phosphorus by plants. Soil Sci. Soc. Am. Proc. 39:1085-1088.
Sudarsanan, K., R. A. Young, and A. J. Wilson. 1977. The structures of
some Cadmium 'Apatites' Cdc(M04.)3 X. 1. Determination of the struc-
tures of Cds(V04)33, CdcfPOahBr, (^.(AcO^Br, and CdnJVO^Br.
Acta -Crystal'Togr. B33:3136-3142.
Sutton, C. D., and D. Gunary. 1969. Phosphate equilibria in soil.
p. 127-134. Iji Rorison, I.H. (ed.) Ecological aspects of the mineral
nutrition of- plants.* Symp. q-f the British Ecological Soc., April
1968.
Syers, i)-.'-K'.;, M-.-.Gr. Broymian, G. W. Smillie, and. R.. B. Corey-. 19731. Phos-
phate, sorption by 'soj-l's'evaluated by»the'L-angrriuir adsorption equation.
Sp.il $ci.>.Soc-. Am/Proe. 37:358-368.
<»$yers, J'. K-.-, T->. [).. Evans-, J'- D'. R." Williams, and J., T. Murdock." 1971.
Phosphate sorption-parameters-of representative soils from Rio Grande
do Sul, Brazil. Soil Sci. 112:267-275.
Syers, J. K., R. Shah, and T. W. Walker. 1969. Fractionation of phos-
phorus in two allivial soils and particle-size separates. Soil
Science 108:283-289.
154
-------
Tahourv, S. A. 1976. The reaction of monocalcium phosphate with kaolinite.
Egypt J. Soil Sci. 16:69-74.
Tahoun, S. A. 1976. The reaction of monocalcium phosphate with calcite.
Egypt 0. Soil Sc1. 16:75-60.
Tallbudeen, 0. 1958. Isotopically exchangeable phosphorus in soils.
111. J. Soil Sc1. 9:120-129.
Tamm, 0. 1932. Uber die oxalatmethode in der chemischen bodenanalyse.
Stockholm Statens. Skogsforskingsinstitute Meddelanden. 27:1-20.
Taylor, A. W., and E. L. Gurney. 1962. Phosphate equilibrium In an
acid soil. Soil Sci. 93:241-245.
Tomson, M. B., J. P. Barone, and G. H. NancoTlas. 1977. Precise calcium
phosphate determination. At. Absorpt. Newsl. 16:117-118.
Turner, F. T., and 0. W. Gilliam. 1976. Effect of moisture and oxidation
status of alkaline rice soils of India and Peru on the adsorption
of soil phosphorus by an anion resin. Plant Soil 45:353-363.
Vakdyanathan, L. V., and P. H. Nye. 1970. The measurement and mechanism
of ion diffusion In soils. VI. The effect of concentration and
moisture content on the counter-diffusion of soil phosphate against
chloride ion. J. Soil Sci. 21:15-27.
Vaidyanathan, L. V., and P. H. Nye. 1971. The measurement and mechanism
of ion diffusion in soils. VII. Counter-diffusion of phosphate
against chloride in a moisture-saturated soil. J. Soil Sc1. 22:
94-100.
Vaidyanathan, L. V., and 0. Tallbudeen. 1968. Rate-controlling processes
in the release of soil phosphate. J. Soil Sci. 19:
Vaidyanathan, L. V., and 0. Tallbudeen. 1970. Rate processes 1n the
desorptlon of phosphate from soils by ion-exchange resins. 0. Soil
Sci. 2:173-183.
Vanderdeelen, J., N. InesPIno, and L. Baert. 1973. Kinetics of phos-
phate adsorption in a soil derived from volcanic ash. Turrialba
23:291-296.
Van Riemsdljk, W. H., F. A. Weststrate, and G. H. Bolt. 1975. Evidence
for a new aluminum phosphate phase: from,reaction rate of phosphate
with aluminum hydroxide. Nature 257:473-474.
Van Rlemsdljk, W. H., F. A. Weststrate,and J. Beek. 1977. Phosphates
1n soils treated with sewage water: 111. Kinetic studies on the
reaction of phosphate with aluminum compounds. J. Environ. Qual.
6:26-29.
155
-------
Vijayachandran, P. K., and R. D. Harter. 1975. Evaluation of phosphorus
adsorption by: a cross section of soil types. Soil Sci. 119:1 T9-1:26.
Vollenweider, R. A. 1968. "Scientific Fundamentals of the Entrophica-
tion of Lakes and Flowing Waters with Particular Reference to Nitrogen
and Phosphorus as Factors in Entrophication." OECD, Paris.
Wang, W. C. 1974. Adsorption of phosphate by river particulate matter.
Water Resour. Bull. 10:662-671.
Webber, M. D., and G. J. Racz. 1970. Soluble complexes in the systems
dicalcium phosphate dihydrate or dimagnesium phosphate trihydrate
equi1ibrated with aqueous salt solutions. Can. J. Soil Sci. 50:
242-253.
Weir, C. C. 1977. Phosphate fixation in Jamaican latosolic soils.
Trop. Agric. (Trinidad) 54:87-93.
Weir, C. C., and R. J. Soper. 1962. Adsorption and exchange studies of
phosphorus in some Manitoba soils. Can. J. Soil Sci. 42:31-42.
White, R. E., and P. H. T. Beckett. 1964. Studies on the phosphate
potentials of soils 1. Plant Soil 20:1-16.
White, R. E., and A. W. Taylor. 1977. Effect of pH on phosphate adsorp-
tion and isotopic exchange in acid soils at low and high additions
of soluble phosphate. J. Soil Sci. 28:48-61.
White, R. E., and A. W. Taylor. 1977. Reactions of soluble phosphate
with acid soils: the interpretation of adsorption-desorption iso-
therms. J. Soil. Sci. 28:314-328.
Wiklander, L. 1950. Kinetics of phosphate exchange in soils. Ann." R.
Agr. Coll. Sweden 17:407-424.
Wild,"A. 1950. Effects of salts on the retention of phosphate by clay
at various pH values.' Trans. 4th I-nt. Gongr. Soil Sci. j Amsterdam.
1: ,1946-1948.
Wildung, R. E., R. L. Schmidt-, and R. C,. Routson. 1977. The phosphorus
status of--eutrophic lake sediments as related to changes in limno-
logicaVconditions—phosphorus mineral components. J.'E-nvi.ron.
Qual. 5:100-104.
Williams, E. G., N. M. Scott, and M. J. McDonald. 1958.' Soil properties.,
and phosphate sorption. J. Sci. Food Agric. 9:551-559.
Wondrausch, J. 1969. Phosphorus sorption in mucky-peat soils. Pol.
J. Soil Sci. 2:97-106.
156
-------
, T. L., and H. L. Brel&nd. 1969. Correlation of A1 and Fe as ex-
tracted by different reagents with phosphate retention in several
soil groups. Soil Crop Sci. Soc. Fla. Proc. 29:78-86.
157
-------
APPENDIX A
Tables of Adsorption Isotherm Parameters
158
-------
Table Al. Adsorption Isotherm Parameters (K.N.Ko and Koc) for Ametryne and selected soil properties
compiled from the literature.
Soil Properties Adsorption Parameters
Soil
Article*
No.
PH
O.C.
(%)
C.E.C.
(me/lOOg)
Kd
K
N
^oc
ALTURA L
6
8.0
2.13
27.6
2.5500E+00
1.1972E+02
COTO t
6
7.7
1.84
14.0
2.5100E+00
T.3641E+02
GUANICA C
6
8.1
2.77
52.1
4.0400E+00
1.4585E+02
RIO PEDftAS SC
6
4.9
2.02
11.5
3.2000E+00
1.5842E+02
CATANO S
6
7.9
1.21
6.9
2.0800E+00
1.7190E+02
HERCEDITA SC
6
8.1
1.38
19.9
2.3800E+00
1.7246E+02
FE CL
6
7.5
1.96
27.6
3.7200E+00
1.8980E+02
HABI CL
6
5.7
2.82
31.0
5.5800E+00
1.9787E+02
AGUADILLA LS
6
7.4
1.44
10.0
3.0800E+00
2.1389E+02
VEGA ALTA SL
6
5.0
2.02
5.6
5.1400E+00
2.5446E+02
CATALINA C
6
4.7
1.09
11.8
2.7800E+00
2.5505E+02
frAternidad c
6
6.3
1.21
36.0
3.3400E+00
2.7603E+02
SAN WON L
6
6.7
1.55
26.1
4.330GE+00
2.7935E+02
NIPE C
6
5.7
3.06
11.9
9.52O0E+OO
3.1111E+02
PANDURA SL
6
5.7
1.15
7.7
3.6300E+00
3.1565E+02
BAYAMON SCL
6
4.7
0.98
5.0
3.2000E+00
3.2653E+02
FRATERNIDAD C
6
5.9
2.42
58.0
8.1400E+00
3.3636E+02
CAYAGUA: SL
6
5.2
1.15
7.3
3.9700E+00
3.4522E+02
AGlrtRRE CL
6
9.0
0.75
14.3
2.7600E+00
3.6800E+02
JOSEFA SL
6
6.0
1.90
16.8
7.160QE+00
3.7684E+02
ALONSO C
6
5.1
1.84
13.8
7.1100E+00
3.8641E+02
C0L050 CL
6
5.7
2.13
23.0
9.16O0E+OO
4.3005E+02
CIALITOS C
6
5.4
2.82
18.6
1.3320E+01
4.7234E+02
HUMATA SCL
6
4.5
0.98
10.1
4.7000E+00
4.7959E+02
MUCARA L
6
5.8
1.90
19.6
1.0460E+0Q
5.5053E+02
TAA SL
6
6.0
0.34
8.0
2.0800E+00
6.1176E+02
MOCA C
6
5.8
2.19
31.0
1.3610E+01
6.2146E+02
Continued
-------
Table A1. (Continued)
Soil Properties Adsorption Parameters
Soil
Article*
PH
O.C.
C.E.C.
No.
{%)
(me/lOOg)
kd
K
N
Koc
VIA L
6
5.1
1.32
39.9
8.4900E+00
6.4318E+02
JUNCOS SC
6
6.2
1.55
13.4
1.0900E+01
,
7.0323E+02
TALANTE SL
6
5.1
0.80
4.0
6.1900E+00
7.7375E+02
TOA L
6
5.3
1.15
13.0
9.7200E+00
8.4522E+02
FORTUNA SCL
6
5.4
1.90
23.3
1.8230E+01
,
9.5947E+02
*See Table A39 for corresponding literature citation. Same comment applies to Tables A2-A38.
Table A2. Adsorption Isotherm Parameters (K.N.Kq and KoC) for Amiben and selected soil properties
compiled from the literature.
Soil Properties Adsorption Parameters
Soil Article* pH O.C. C.E.C.
No. (%) (me/lOOg) Kq K N Koc
POYGAN SICL
36
7.2
5.70
2.4000E-01
4.2105E+00
KEWAUNEE C
36
6.4
2.19
1.1000E-01
5.0228E+00
FARGO C
9
7.9
4.56
30.1
3.0000E-01
6.5789E+00
ANSELMO SL
9
7.0
0.98
7.0
1.0000E-01
1.0204E+01
KEITH SL
9
6.2
1.67
11.6
3.OOOOE-Ol
1.7964E+01
MONONA SL
9
5.8
2.42
17.5
5.0000E-01
2.0661E+01
ELLA LS
36
3.8
0.92
2.4000E-01
2.6087E+01
SHARPSBURG SCL
9
5.8
2.54
24.5
l.OOOOE+OO
3.9370E+01
GALLI ON FSL
34
6.2
0.35
2.8
1.1000E+00
3.1429E+02
TALOKA SL
34
6.4
0.40
4.6
1.9000E+00
4.7500E+02
CROWLEY SL
34
6.5
0.92
12.6
4.5000E+00
4.8913E+02
SHARKEY C
34
6.7
0.75
33.4
6.5000E+00
8.6667E^02
-------
Table A3. Adsorption Isotherm Parameters (K,N,Kq and Kqc) for Atrazfne and selected soil properties
compiled from the literature.
Soil Properties Adsorption Parameters
Soil
Article*
No.
PH
O.C.
{%)
C.E.C.
(me/lOOg)
Kp
K
Koc.
kilLA RP
38
5.9
12.70
6.0000E+00
4.7244E+01
KAPAA HFL
38
.4.4
5.70
#
2.9QGQE+00
5.0877E+O1
SANDY t
2$
7,1
1.93
11.0
1.0000E+00
5.1813E+01
LAKELAND SL
13
6:2
1.90
2.9
l.OOOOE+OO
1.0000
0
85
5.2632E+01
KAIPOIOI LBF
38
5.4
16.70
• .
9.3000E+00
5.5689E+01
BQYCE L
16
8.0
1.27
20.0
7.7800E-01
«
6.1260E+01
PONDER SIL
16
7.7
1.67
31.9
1.2000E+00
7.1856E+01
METQLIUS SL
16
7.1
0.80
18.5
6*1500E-01
#
7.6875E+01
CHEHALIS SL
16
5.2
0.98
16.9
8.27Q0E-01
#
8.4388E+01
KEITH FSL
id
6.3
1.67
•'
1.4930E+O0
1.4930
0
83
8.9401E+01
BEGBROKE $ L
7
7.1
1.11
•
l.OOOOE+OO
»
9.0090E+01
QUINCY SL.
16
8.0
0.28
11.0
2.6000E-01
•
9.2857E+01
VALENTINE LFS
19
5.9
0.80
7.6800E-01
0^7680
0
81
9.60O0E+01
CEIL
42
5.6
0.90
6.8
8.9000E-01
0.8900
1
04
9.8889E+01
BATES SL
11
6.5
0:80
9,3
8.0000E-01
i.ooooe+02
MOLOKAl LHL
38
6.3
2.30
2.3000E+00
1.0000E+02
DARK SL
29
6,3
12.00
18.0
1:2300E+01
1.0250E+02
GILA SIC
16
8.0
0.63
29.1
6.4900E-Q1
1.0302E+Q2
H00D8URN SIL
16
5,2
1.32
12.8
1.4480E+00
1.09705+02
EUSTIS
42
5.6
0.56
5.2
6.2000E-01
0.62OO
0
79
1.1071E+02
MONONA SICL
19
5.8
1.67
•
1.9240E+00
1.9240
0
85
1.1521E+02
MENFRO SL
U
5.3
1.38
9.1
1.7000E+00
1.2319E+02
DESCHUTES SL
16
5.9
0.51
12.9
6.7600E-01
#
1.3255E+02
ELDON 5L
11
5.9
1.73
12.9
2.5000E+00
1.4434E+02
HASERSTOWN SICL
13
5.5
2.48
12.5
3.7000E+00
3.7000
0
87
1.4919E+02
SHELBY L
U
4.3
2.07
20.1
3.2000E+00
# '
1.5459E+02
WEBSTER
42
7.3
3.87
54.7
6.0300E+00
6.0300
0
73
1.5581E+02
CHILLUM SIL
13
4.6
2.54
7.6
4.0000E+00
4.0000
0
87
1.5748E+02
(Continued)
-------
Table A3. (Continued)
Soil Properties Adsorption Parameters
Soil
Article*
No.
pH
O.C.
(*)
C.E.C.
(me/lOGg)
«D
K
N
Koc
OSWEGO SCL
11
6.4
1.67
21.0
2.7000E+00
1.6168E+02
WEHADKEE SIL
13
5.6
1.09
10.2
1.8000E+00
1.8000
0^84
1.6514E+02
DRUMMER C L
25
8.0
3.63
40.0
6.3000E+00
1.7355E+02
PUTNAM SL
11
5.3
1.09
12.3
1.9000E+00
1.7431E+02
LINTONIA LS
11
5.3
0.34
3.2
6.0000E-01
1.7647E+02
SHARPSBURG SICL
19
5.2
2.19
3.8900E+00
3.8900
0^83
1.7763E+02
DRUMMER C L
25
6.0
3.63
40.0
6.5000E+00
1.7906E+02
MARSHALL SCL
11
5.4
2.42
21.3
4.5000E+00
4.5000
i!oo
1.8595E+02
BAXTER CSL
22
6.0
1.21
11.2
2.3000E+00
m
1.9008E+02
SALIX L
11
6.3
1.21
17.-9
2.3000E+00
1.9008E+02
NEWTONIA SL
11
5.2
0.92
8.8
1.8000E+00
1.9565E+02
SUMMIT SC
11
4.8
2.82
35.1
5.6000E+00
1.9858E+02
CUMBERLAND SL
11
6.4
0.69
6.5
1.4000E+00
.
2.0290E+02
GERALD SL
11
4.7
1.55
11.0
3.2000E+00
2.0645E+02
LEBANON SL
11
4.9
1.04
7.7
2.2000E+00
2.1154E+02
CLARKSVILLE CSL
11
5.7
0.80
5.7
1.7000E+00
#
2.1250E+02
SHARKEY C
11
5.0
1.44
28.2
3.1000E+00
2.1528E+02
KNOX SL
11
5.4
1.67
18.8
3.6000E+00
2.1557E+02
DRUMMER C L
25
5.3
3.63
40.0
8.2000E+00
2.2590E+02
GRUNDY SCL
11
5.6
2.07
13.5
4.8000E+00
2.3188E+02
WAVERLY SL
11
6.4
1.15
12.8
3.0000E+00
,
2.6087E+02
MARIAN SL
11
4.6
0.80
9.9
2.2000E+00
.
2.7500E+02
WABASH C
11
5.7
1.27
40.3
3.7000E+00
.
2.9134E+02
SARPY L
11
7.1
0.75
14.3
2.2000E+00
2.9333E+02
DRUMMER C L
25
4.7
3.63
40.0
1.0700E+01
2.9477E+02
LINDLEY L
11
4.7
0.86
6.9
2.6000E+00
3.0233E+02
DRUMMER C L
25
3.9
3.63
40.0
1.2600E+01
.
3.4711E+02
UNION SL
11
5.4
1.04
6.8
4.1000E+00
3.9423E+02
-------
Table A4. Adsorption Isotherm Parameters (K,N,Kd and K^) for Carbofuran and selected soil properties
compiled from the literature.
Soil Properties Adsorption Parameters
Soil
Article*
PH
O.C.
C.E.C.
No.
<*)
(me/lOOg)
*D
K
N
Koc
SEDIMENT B
45
7.1
1.85
3.0000E-01
0.3000
0.90
1.6216E+01
SEDIMENT A
45
7.7
1.50
3.3000E-01
0.3300
1.03
2.2000E+Q1
VERSAILLES
45
6.4
1.10
2.6000E-01
0.2600
0.88
2.370lEf07
HUMUS
45
6.8
10.97
3.4800E+00
3.4800
0.91
3.1723E+01
LIMAGNE
45
8.0
2.08
7.2000E-01
0.7200
1.03
3.4615E+01
CKAL6US
45
8.1
1 ;62
6.1000E-01
0.6100
0.97
3.7654E+01
EARTH/HUMUS
45
6.5
4.16
1.6500E+00
1.6500
0.99
3.9663E+01
Table A6. Adsorption I&otherm Parameters (k,N,KQ and KqC) for Chlorobromuron and selected soil properties
compiled from the literature.
Soil
Soil Properties
Article* pfl OTCT^ C.E.C.
No. (X) (me/lOOg)
%
Adsorption Parameters
N
*oc
WEYBURN OXBOW L 18
REGINA HEAVY C 18
ASQUITH SL 18
INDIAN HEAD CL 18
MELFORT L 18
6.5
7.7
7.5
7.8
5.9
3.72
2.39
1.02
2.34
6.05
2.0300E+01
1.7800E+01
7.9000E+00
2.2800E+01
1.1730E+02
20.3000
17.8000
7.9000
22.13000
117.3000
0.83
0.71
0.73
0.68
0.45
5.4570E+02
7.4477E+02
7.7451E+02
9.7436E+02
1.9388E+03
-------
Table A6. Adsorption Isotherm Parameters (K.N.Kq and K^) for Chloroxuron and selected soil properties
compiled from the literature.
Soil Properties Adsorption Parameters
Soil Article* pH O.C. C.E.C.
No. {%) (me/lOOg) KD K N KQC
TOLL FARM HP
8
7.4
11.70
41.0
GREAT HOUSE SL
8
6.3
12.00
18.0
ROSEMAUNDE SCL
8
6.7
1.76
14.0
TRANSCOED SICL
8
6.2
3.69
#
WEED RES. SL
8
7.1
1.93
11.0
3.3000E+02
4.7500E+02
7.0000E+01
1.7500E+02
1.2000E+02
2.8205E+03
3.9583E+03
3.9773E+03
4.7425E+03
6.2176E+03
Table A7. Adsorption Isotherm Parameters (K.N.Kp and KgC) for Chlorthiamid and selected soil properties
compiled from the literature.
Soil
Article*
No.
Soil Properties
pH O.C. C.E.C.
{%) (me/lOOg)
Kd
Adsorption Parameters
N
K,
oc
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
33
33
33
33
33
33
19.20
3.93
4.67
4.56
5.56
3.37
9.8000E+00
3.6000E+00
4.8000E+00
4.7000E+00
6.0000E+00
4.5000E+00
5.1042E+01
9.1603E+01
1.0278E+02
1.0307E+02
1.0791E+02
1.3353E>02
-------
Table A8. Adsorption Isotherm Parameters (K,N,Kq and KqC) for Cis-Telone and selected soil properties
compiled from the literature.
Soil Properties Adsorption Parameters
Soil Article* pH O.C. C.E.C.
No. (%) (me/lOOg) KD K N
HUMUS
PEATY
HUMUS
PEATY
HUMUS
PEATY
22
22
22-
22
22
22
3.17
10.39
3.1?
10.39
3.17
10.39
1.4000E+01
4.7000E+01
Z. 2000E+01
7.8000E+01
3.8000E+01
1.3000E+02
4.4164E+02
4.5236E+02
6.9401E+02
7.5072E+02
1.1987E+03
1.2512E+03
Table A9. Adsorption Isotherm Parameters (K,N,Kg and KgC) for Dieamba and selected soil properties
compiled from the literature.
Soil
Article*
No.
P~
Soil Properties
O.C. C.E.C;
(%) (me/lOOg)
KO
Adsorption Parameters
N
Kqc
INDIAN HEAD L 41
MELFORT L 17
WEYBURN OXBOW L 41
WEYBURN OXBOW L 17
MELFORT L 41
7.8
5.9
6.5
6.5
5.9
2.35
6.05
3.72
3.72
6.05
3.0000E-02
8.0000E-02
5.0000E-02
7.0000E-02
3.0000E-01
0.0800 1.30
0.0700 1.07
1.2766E+00
1.3223E+00
1.3441E+00
1.8817E+00
4.9587E+00
-------
Table A10. Adsorption Isotherm Parameters (K.N.Kq and KoC) for Dimethylamine and selected soil proper^
ties compiled from the literature.
Soil Properties Adsorption Parameters
Soi 1
Article*
pH
O.C.
C.E.C.
No.
{%)
(me/lOOg)
kd
K
N
^oc
WEYBURN OXBOW L
17
6.5
3.73
1.1700E+01
11.7000
1.00
3.1367E+02
INDIAN HEAD L
17
7.8
2.35
9.2000E+00
9.2000
0.99
3.9149E+02
ASQUITH SL
17
7.5
1.02
4.5000E+00
4.5G00
0.99
4.4118E+02
REGINA HEAVY C
17
7.7
2.40
1.2000E+01
12.0000
1.00
5.0000E+02
MELFORT L
17
5.9
6.17
3.2600E+01
32.6000
1.00
5.2836E+02
Table All. Adsorption Isotherm Parameters (K,N,Kq and K^) for Dipropetryn and selected soil properties
compiled from the literature.
Soil Properties Adsorption Parameters
Soil
Article*
PH
O.C.
C.E.C.
No.
(*)
(me/lOOg)
kd
K
N
X
o
n
COBB S
30
7.3
0.34
3.8
1.3200E+00
1.3200
0.86
3.8824E+02
TELLER FSL
30
5.7
0.75
8.6
6.1800E+00
6.1800
0.86
8.2400E+02
PORT SIC
30
6.3
1.04
17.9
8.9100E+00
8.9100
0.81
8.5673E+02
BREWER CL
30
5.8
1.61
13.5
1.8500E+01
18.5000
0.89
1.1491E+03
COBB
30
5.3
1.21
9.0
3.2500E+01
32.5000
0.73
2.6850E+03
-------
Table A12-. Adsorption Isotherm Parameters (K,N,Kq and KqC) for Dlsulfoton and selected soil properties
compiled from the literature.
Soil Properties
Adsorption Parameters
Soil
Article*
PH
o.c.
C.E.C.
No.
(*)
(me/IOOg)
Kp
K
N
Koc
ELKH RN SL
15
6.6
0.86
•
5.01OOE+OO
5.0100
0.94
5.8256E+02
PEACOCK
15
7.6
11.00
74.0
7.0300E+01
70.3000
0.94
6.3909E+02
BR0AD8ALK
1
8.1
0.90
10.4
5.8000E+00
5.8000
1.01
6.4444E+02
ISLtHAH
1
7.5
7.60
44.8
4.9100E+01
4941000
0.87
6.4605E+02
60TTISHAM
7.7
8.B0
48.2
5.8600E+01
58.6000
0.97
6.6591E+02
PRICKWILLOW
\
5.1
15.00
83.4
1.0050E+02
100.5000
1.00
6.7000E+02
WORLINGTON
1
8.1
0.70
6.3
5.3000E+00
5.3000
1.09
7.6714E+02
broadbalk
1
7.8
2.70
19.8
2.1500E+01
21.5000
1.00
7.9630E+02
SPINNEY
1
7.2
12.00
66.4
9.5700E+01
95.7000
0.80
7.9750E+02
OAKINGTON
1
7.2
1.80
14.0
1.6000E+01
16.0000
0.92
8.8889E+02
STRETHAM
1
7.5
1.40
13.0
1.4700E+01
14.7000
0.81
1.0500E+03
WOBURN
1
6.5
1.80
10.7
2.0000E+01
20.0000
1.00
1.1111E+03
WICKEN
1
8.0
1.70
21.9
2.0300E+01
20.3000
0.8O
1.1941E+03
MOULTON
1
8.1
1.70
10.6
2.1100E+01
21.1000
0.81
1.2412E+03
WOBURN
1
6.8
1.10
10.2
1.4900E+01
14.9000
0.93
1.3545E+03
WOBURN
1
6.8
1.30
10.6
2.0500E+01
20.5000
0.85
1.5769E+03
SWEENEY SCL
15
6.3
0.65
1.1490E+01
11.4900
0.98
1.7677E+03
ISLEHAH
1
6.3
2.80
18.2
5.5500E+0I
55.5000
0.88
1.982TE+03
HUGO GRAVELLY SL
15
5.5
0.12
3.0300E+00
3.0300
0.98
2.525OE+03
TIERRA CL
15
6.2
0.33
#
3.6860E+01
36.8600
1.05
1.1170E+04
-------
Table A13. Adsorption Isotherm Parameters (K,N,Kq and K^) for Diuron and selected soil properties
compiled from the literature.
Soil Properties
Adsorption
Parameters
Soi 1
Article*
PH
O.C.
C.E.C.
.No.
(%)
(me/lOOg)
kd
K
N
O
o
*4
IREDELL C
12
5.6
6.17
20.9
9.5200E-01
1.5429E+01
ONTARIO C
12
5.9
0.86
8.4
2.0800E-01
2.4186E+01
LAKELAND SL
12
6.2
1.88
2.9
1.0980E+00
5.8404E+01
TIFTON LS
12
4.9
0.56
2.4
6.1800E-01
1.1036E+02
BENEVOLA C
12
7.6
1.30
20.1
1.4930E+00
1.1485E+02
BELTSVILLE SIL
12
4.3
1.40
4.2
1.6670E+00
1.1933E+02
BERKLEY C
12
7.3
0.99
34.4
1.2500E+00
1.2626E+02
BERKLEY SIC
12
7.1
4.63
33.7
5.8700E+00
1.2678E+02
WEHADKEE SIL
12
5.6
1.11
10.2
1.41OOE+OO
1.2703E+02
BENEVOLA SIC
12
7.7
2.70
19.5
3.6210E+00
1.3411E+02
TRIPP L
12
7.6
0.86
14.7
1.1730E+00
1.3640E+02
RUSTON SL
12
5.1
1.05
3.4
1.4930E+00
1.4219E+02
CECIL SC
12
5.3
1.09
3.6
1.5790E+00
1.4486E+02
STERLING CL
12
7.7
0.94
22.5
1.41OOE+OO
1.5000E+02
CHRISTIANA L
12
4.4
0.57
5.6
8.8200E-01
1.5474E+02
ASCALON SCL
12
7.3
0.85
12.7
1.3290E+00
1.5635E+02
OOSTER SIL
12
4.7
1.31
6.8
2.1430E+00
1.6359E+02
HAGERSTOWN SICL
12
7.5
1.30
8.8
2.1430E+00"
1.6485E+02
CHESTER L
12
4.9
1.67
5.2
2.8130E+00
1.6844E+02
GARLAND C
12
7.7
0.65
23.2
1.0980E+00
1.6892E+02
CATALINA C
6
4.7
1.09
11.8
1.8600E+00
1.7064E+02
THURLOW CL
12
7.7
1.25
21.6
2.1430E+00
1.7144E+02
HAGERSTOWN SICL
12
5.5
2.48
12.5
4.2590E+00
1.7173E+02
RIO PIEDRAS SI C
6
4.9
2.02
11.5
3.6300E+00
1.7970E+02
CHILLUM CIL
12
4.6
2.54
7.6
4.6150E+00
1.8169E+02
TOLEDO SIC
12
5.5
2.80
29.8
5.6380E+00
?.0"I36E+0?
-------
Table A13. (Continued)
Soil Properties Adsorption Parameters
Soil Article* pH O.C. C.E.C.
Ho. (t) (me/lOOg) Kp K H K<,c
MOCARA L
6
5.8
3.06
19.6
6.53OOE+0O
2.1340E+02
BARNES CL
12
7.4
3.98
33.8
8.5140E+00
2.1392E+02
HUMALTA SI C L
6
4.5
0.98
10.1
2.1300E+00
2.1735E+02
BOSKET S1L
12
5.8
0.57
8.4
1.2500E+00
2.1930E+02
TRUCKTON SL
12
7.0
0.25
4.4
5.5600E-01
2.2240E+02
CROSBY SIL
12
4.8
1.90
11.5
4.2590E+00
2.2416E+Q2
IRDELL SIL
12
5.4
3.04
17.0
6.9050E+00
2.2714E+02
BAYMON SCL
6
4.7
0.98
5.0
2.2900E+00
2.3367E+02
DUNDEE SICL
12
5.0
0.96
18.1
2.2460E+00
2.3396E+02
PANTURA S L
6
5.7
2.02
7.7
4.7300E+00
2.3416E+02
BEGBROKE S L
7
7.1
1.11
2.7000E+00
2.4324E+02
MERCEDITA SI C
6
8.1
2.19
19.9
5.4600E+00
2.4932E+02
ALQNSO C
6
5.1
1.84
13.8
4.6300E+00
2.5163E+02
AQUIRRE CL
6
9.0
1.84
13.8
4.6300E+00
2.5163E+02
ALTURA L
6
8.0
2.13
27.6
5.3600E+00
2.51(64E+02
CAVAGUA S L
6
5.2
1.15
7.3
2.9600E+00
2.5739E+02
SHARKEY C
12
6.2
2.25
40.2
6.3640E+00
2.8284E+02
TALANTE S L
6
5.1
0.80
4.0
2.3600E+00
2.9500E+02
FE C L
6
7.5
1.96
27.6
5.8600E+00
2.9898E+02
TOA L
6
5.3
1.15
13.0
3.5600E+00
3.0957E+02
VEGA ALTA S L
6
5.0
2.02
5.6
6.3000E+00
4
3.1168E+02
CATANO S
6
7.9
1.21
6.9
3.9000E+00
3.2231E+02
(Continued)
-------
Table AT3. (Continued)
Soil Properties Adsorption Parameters
Soil Article* pH O.C. C.E.C.
No. (*) (me/lOOg) KD K N Koc
AQUAOILLA LS
6
7.4
1.44
10.0
4.7300E+00
3.2847E+02
KEYPORT SIL
10
5.4
1.21
4.0000E+00
4.0000
1
25
3.3058E+02
GUANICA C
6
8.1
2.77
52.1
9.3900E+00
3.3899E+02
TOA S L
6
6.0
0.34
8.0
1.2600E+00
3.7059E+02
BRIDGETS SIL
8
8.0
3.09
24.0
1.2000E+01
3.8835E+02
VIA L
6
5.1
1.32
39.9
5.1300E+00
3.8864E+02
TRAWSCOED SICL
8
6.2
3.69
12.0
1.6000E+01
4.3360E+02
CIALITOS C
6
5.4
2.82
18.6
1.2400E+01
4.3972E+02
TOLL FARM HP
8
7.4
11.70
41.0
5.3000E+01
4.5299E+02
COTO C
6
7.7
1.84
14.0
9.3600E+00
5.0870E+02
MABI C
6
7.0
2.82
55.2
1.4460E+01
5.1277E+02
FRATERNIDAD C
6
5.9
2.92
58.0
1.5890E+01
5.4418E+02
REGINA HEAVY C
18
7.7
2.39
1.3400E+01
13.4000
0
70
5.6067E+02
INDIAN HEAD CL
18
7.8
2.34
.
1.3300E+01
13.3000
0
78
5.6838E+02
C0L0S0 C L
6
5.7
2.13
23.0
1.2160E+01
5.7089E+02
FRATERNIDAD C
6
6.3
1.21
36.0
6.9600E+00
5.7521E+02
ROSEMAUNDE SCL
8
6.7
1.76
14.0
1.0200E+01
5.7955E+02
CECIL LS
10
5.8
0.40
2.4000E+00
2.4000
0
95
6.0000E+02
GREAT HOUSE S L
8
6.3
12.00
18.0
7.5000E+01
6.2500E+02
MOCA C
6
5.8
1.90
31.0
1.2030E+01
6.3316E+02
JOSEFA SIL
6
6.0
1.90
16.8
1.2060E+01
6.3474E+02
JUNCOS SI C
6
6.2
1.55
13.4
1.0100E+G1
6.5161E+-2
KIRTON SI
8
7.6
1.50
13.0
1.0000E+01
6.6667E+02
ASQUITH SL
18
7.5
1.02
6.9000E+00
6.9000
0
63
6.7647E+02
WEED RES. SL
8
7.1
1.93
11.0
1.3600E+01
.
7.0466E+02
(Continued)
-------
Table A13. (Continued)
Soil Properties Adsorption Parameters
Soil Article* pH ffjCT C.E.C.
No. (%) (me/lOOg) Kq K N K,,,.
FORTUNA SI C L
6
5.4
1.90
23.3
1.3400E+01
7.0526E+02
BOXWORTH C
8
7.9
2.08
22.0
1.5000E+01
7.2115E+02
WEYBURN OXBOW L
18
6.5
3.72
2.6900E+01
26.9000
0
55
7.2312E+02
LISCOMBE SL
8
6.2
3.45
13.0
2.5000E+01
7.2464E+02
MABI CL
6
5.7
1.38
31.0
1.0330E+01
7.4855E+02
VALENTINE LFS
40
6.6
0.80
10vl
6.5000E+00
8.1250E+02
MONONA SIGL
40
6.5
1.67
21.2
1i 4300E+01
8.5629E+02
TERRINGTON SI
8
8.0
1.54
15.0
1.4000E+01
9.0909E+02
SAN ANTON L
6
6.7
1.55
26.1
1.5800E+01
1.0194E+03
NIPE CL
6
5.7
1.15
11.9
1.5100E+01
1.3130E+03
MELFORT L
18
5/9
6.05
8.3300E+01
83.3000
0
95
1.3769E+03
-------
Table A14. Adsorption Isotherm Parameters (K.N.Kg and Koc) for Fenuron and selected soil properties
compiled from the literature.
Soil Properties Adsorption Parameters
Soil
Article*
pH
O.C.
C.E.C.
Wo.
(%)
(me/lOOg)
kD
K
N
^oc
ROSEMAUNDE SCL
8
6.7
1.76
14.0
3.4000E-01
1.9318E+01
TRAWSCOED SICL
8
6.2
3.69
12.0
7.3000E-01
.
.
1.9783E+01
WEED RES. SL
8
7.1
1.93
11.0
4.4000E-01
.
.
2.2798E+01
TOLL FARM HP
8
7.4
11.70
41.0
2.9000E+00
#
2.4786E+01
ASQUITH SL
18
7.5
1.02
3.0000E-01
0.3000
0.97
2.9412E+01
WEYBURN OXBOW L
18
6.5
3.72
#
1.1000E+00
1.1000
0.92
2.9570E+01
REGINA HEAVY C
18
7.7
2.39
8.0000E-01
0.8000
0.93
3.3473E+01
GREAT HOUSE S L
8
6.3
12.00
18.0
4.7000E+00
3.9167E+01
INDIAN HEAD CL
18
7.8
2.34
1.6000E+00
1.6000
0.85
6.8376E+01
MELFORT L
18
5.9
6.05
•
8.2000E+00
8.2000
0.68
1.3554E+02
Table A15. Adsorption Isotherm Parameters (K,N,Kp and KoC) for Lindane and selected soil properties
compiled from the literature.
Soil Properties Adsorption Parameters
Soil Article* pR O.C. C.E.C.
No. (%) (me/lOOg) K0 K N Koc
FOX SL 39 . 1.84 . 1.7300E+01 . . 9.4022E+02
BR00KST0N 39 . 2.10 . 2.2700E+01 . . 1.0B10EK)3
HONEYWOOD LS 39 . 1.67 . 2.0400E+01 . . 1.2216E+03
-------
Table A16. Adsorption Isotherm Parameters (K,N,Ko and KoC) for Linuron and selected soil properties
compiled from the literature.
Soil Properties Adsorption Parameters
Soil Article* pH O.C. C.E.C.
No. {%) (me/lOOg) Kq K N ^
COLTS NECK
20
4.2
1.20
7.7
1.4940E+00
1.2450E+02
DARK SL
29
6.3
12.00
18.0
1.7000E+01
1.4167E+02
DUTCHESS
20
5.5
2.90
12.7
1.1748E+01
4.0510E+02
WHIPPAHY
20
5.6
1.90
9.4
8.3080E+G0
4.3726E+02
WHIPPANY
20
5.6
1.90
9.4
8.9030E+00
4.6858E+02
WEYBURN OXBOW L
18
6.5
3,72
•
1.91OOE+Ol
19.1000
0
70
5.1344E+02
SASSAFRAS
20
5.2
2.00
7.7
1.0286E+01
5.1430E+02
DUTCHESS
20
5.3
2.90
12.7
1.5417E+01
5.3162E+02
TOLL FARM HP
8
7.4
11.70
41.0
6.3000E+01
5.3846E+02
COLLINGTON
20
5.0
2.60
12.8
1.4180E+01
5.4538E+02
WASHINGTON
20
6,0
2.40
11.2
1.3391E+01
5.5796E+02
WASHINGTON
20
6.2
2.40
11.2
1.3391E+01
5.5796E+02
SQUIRES
20
6.5
1.70
7.6
9.7930E+00
5.7606E+02
COOL!NGTON
20
4.7
2.60
12.8
1.5048E+01
5.7877E+02
SANDY L
29
7.1
1.93
11.0
1.1400E+01
5.9067E+02
SASSAFRAS
20
5.2
2.00
7.7
1.2000E+01
6.0000E+02
GREAT HOUSE SL
8
6.3
12.00
18.0
7.3000E+01
6.0833E+G2
ANNANDALE
20
5.8
1.70
11.3
1.1385E+01
6.6971E+02
SQUIRES
20
6.6
1.70
7.0
1.1385E+01
6.6971E+02
ASQUITH SL
18
7.5
1.02
a
6.9000E+00
6.9000
0
75
6.7647E+02
ANNANDALE
20
5.9
1.70
11.3
1.2000E+01
7.0588E+02
INDIAN HEAD CL
18
7.8
2.34
1.7800E+01
17.8000
0
65
7.6068E+02
REGINA HEAVY C
18
7.7
2.39
1.8200E+01
18.2000
0
70
7.6151E+02
BERMUDIAN
20
6.0
1.60
13.2
1.3700E+01
8.5625E+02
(Continued)
-------
Table A16. (Continued)
Soil Properties Adsorption Parameters
Soil Article* pH O.C. C.E.C.
No. (%) (me/lOOg) Kq K N Kqc
BERMUDIAN
20
6.0
1.60
13.2
1.4018E+01
8.7612E+02
BEGBROKE S L
7
7.1
1.11
1.0800E+01
9.7297E+02
COLTS NECK
20
4.2
1.20
7.7
1.2000E+01
1.0O00E+03
TRAWSCOED SICL
8
6.2
3.69
12.0
5.0000E+01
1.3550E+03
MELFORT L
18
5.9
6.05
,
9.7700E+01
97.7000 0.77 1.6149E+03
ROSEMAUNDE SCL
8
6.7
1.76
14.0
3.5000E+01
1.9886E+03
LAKEWOOD
20
3.5
0.50
1.8
1.0815E+01
2.1630E+03
WEED RES. SL
8
7.1
1.93
11.0
4.7000E+01
2.4352E+03
LAKEWOOD
20
3.6
0.50
1.8
1.3390E+01
2.6780E+03
-------
Table A17. Adsorption Isotherm Parameters (K,N,Kq and KoC) for Malathion and selected soil properties
compiled from the literature.
Soil Properties Adsorption Parameters
Soil Article* pH O.C. C.E.C.
No. (%) (me/lOOg) Kg K H KqC
COLTS NECK
20
4.5
1.20
7.7
6.9490E+00
5.7908E+02
WASHINGTON
20
6.0
2.40
11.2
1.6667E+01
6.9446E+-02
WHIPPANY
20
5.7
1.90
9.4
1.3256E+01
6.9768E+02
COLTS NECK
20
4.8
1.20
7.7
8.8680E+00
7.3900E+02
LAKEHOOD
20
4.7
0.50
1.8
4.2340E+00
8.4680E+02
LAKEWOOD
20
4.6
0.50
1.8
4.2860E+00
8.5720E+02
WHIPPANY
20
5.7
1.90
9.4
1.6667E+01
8.7721E+02
SASSAFRAS
20
5.3
2.00
7.7
2*4483E+01
1.2241E+03
SASSAFRAS
20
5.1
2.00
7.7
2.6697E+01
1.3348E+03
COLLINGTON
20
5.7
2.60
12.8
3.6512E+01
1.4043E+03
WASHINGTON
20
6.1
2.40
11.2
3.4444E+01
1.4352E+03
DUTCHESS
20
5.7
2.90
12.7
4,7143E+01
1.6256E+03
ANNANDALE
20
6.2
1.70
11.3
3.3478E+01
1.9693E+03
SQUIRES
20
6.4
1.70
7.0
3.6512E+01
2.1478E+03
COLLINGTON
20
5.6
2.60
12.8
5.6667E+01
2.1795E+03
DUTCHESS
20
5.8
2.90
12.7
6.6923E+01
2.3077E+03
BERMUDIAN
20
6.4
1.60
13.2
4.0633E+01
2.5396E+03
SQUIRES
20
6.6
1.70
7.0
6.4074E+01
3.7691E+03
BERMUDIAN
20
6.4
1.60
13.2
6.6923E+01
4.1827E+03
ANNANDALE
20
6.1
1.70
11.3
7.6956E+01
4.5268E+03
-------
Table A18. Adsorption Isotherm Parameters (K.N.Kq and KoC) for Methyl Parathion and selected soil prop-
erties compiled from the literature.
Soil Properties Adsorption Parameters
Soil Article* pH O.C. C.E.C.
¦No. (X) (me/lOOg) KD K N Koc
WEBSTER
42
7.3
3.87
54.7
1.3390E+01
13.3900
0.75
3.4599E+02
CECIL
42
5.6
0.90
6.8
3.9500E+00
3.9500
0.85
4.3889E+02
EUSTIS
42
5.6
0.56
5.2
2.7200E+00
2.7200
0.86
4.8571E+02
SWEENEY SCL
15
6.3
0.65
1.9560E+01
19.5600
1.03
3.0092E+03
HUGO GRAVELLY SL
15
5.5
0.12
8.8700E+00
8.8700
1.04
7.3917E+03
TIERRA CL
15
6.2
0.33
2.6760E+01
26.7600
1.04
8.1091E+03
ELKHORN SL
15
6.0
0.09
1.3700E+01
13.7000
1.04
1.5930E+04
Table A19. Adsorption Isotherm Parameters (K,N,Kq and Koc) for Methyl Urea and selected soil properties
compiled from the literature.
Soil Properties Adsorption Parameters
Soil Article* pH O.C. C.E.C.
No. {%) (me/lOOg) KD K N
TOLL FARM HP
6
7.4
11.70
41.0
ROSEMAUNDE SCL
8
6.7
1.76
14.0
TRAWSCOED SICL
8
6.2
3.69
12.0
GREAT HOUSE S L
8
6.3
12.00
18.0
WEED RES. SL
8
7.1
1.93
11.0
5.6000E+00
1.0000E+00
2.1000E+00
7.2000E+00
1.4000E+00
4.7863E+01
5.6818E+01
5.6911E+01
6.0000E+01
7.2539E+01
-------
Table A20. Adsorption isotherm Parameters (K.N.Kq and KoC) for Metobromuron and selected soil properties
compiled from the literature.
Soil Properties Adsorption Parameters
Soil
Article*
PH
O.C.
C.E.C.
No.
(%)
(me/lOOg)
*0
K
N
*oc
REGIMA HEAVY C
18
7.7
2.39
•
4.3000E+00
4.3000
0.83
1.7992E+02
ASQUITH SL
18
7.5
1.02
•
2.1000E+00
2.1000
0.89
2.0588E+Q2
WEYBURN OXBOW L
18
6.5
3.72
¦
1.1100E+01
11.1000
0.64
2.9839E+02
INDIAN HEAD CI
18
7.8
2.34
•
9.4OOOE+0O
9.4000
0.68
4.0171E+Q2
HELFORT L
18
5.9
6.05
•
6.1400E+01
61.4000
0.49
1.0149E+03
-------
Table A21. Adsorption Isotherm Parameters (K,N,Kd and KoC) for Monolinuron and selected soil properties
compiled from the literature.
Soil Properties Adsorption Parameters
Soil
Article*
PH
O.C.
C.E.C.
No.
(%)
(me/lOOg)
Kd
K
N
^oc
ASQUITH SL
18
7.5
1.02
1.2000E+00
1.2000
0.84
1.I765E+02
WEYBURN OXBOW L
18
6.5
3.72
5.5000E400
5.5000
0.80
1.4785E+02
REGINA HEAVY G
18
7.7
2.39
3.6000E+00
3.6000
0.80
1.5063E+02
TOLL FARM HP
8
7,4
11.70
41.0
2.1000E+01
,
1.7949E+02
GREAT HOUSE SL
8
6.3
12.00
18.0
2.5000E+01
2.0833E+02
INDIAN HEAD CL
18
7.8
2.34
#
5.8000E+00
5.8000
0.69
2.4786E+02
TRAWSCOED SICL
8
6.2
3.69
12.0
1.1000E+01
2.98iGE+02
ROSEMAUNDE SCL
8
6.7
1.76
14.0
8.1000E+00
#
4.6023E+02
WEED RES. SL
8
7.1
1.93
11.0
9.6000E+00
m
4.9741E+02
MELFORT L
18
5.9
6.05
.
3.2400E+01
32.4000
0.69
5.3554E+02
LAKELAND SL
13
6.2
1.90
2.9
1.1000E+00
1.1000
0.70
5.7895E+01
SANDY L
29
7.1
1.93
11.0
1.5000E+00
7.7720E+Q]
DARK SL
29
6.3
12.00
18.0
9.5900E+00
#
7.9917E+01
ASQUITH SL
18
7.5
1.02
.
1.OOOOE+OO
1.0000
1.04
9.8039E+01
CECIL LS
10
5.8
0.40
4.OOOOE-Ol
0.4000
1.20
1.0000E+02
CHILLUM SIL
13
4.6
2.54
7.6
3.3000E+00
3.3000
0.84
1.2992E+02
REGINA HEAVY C
18
7.7
2.39
3.2000E+00
3.2000
0.84
1.3389E+02
WEYBURN OXBOW L
18
6.5
3.72
5.8000E+00
5.8000
0.80
1.5591E+02
HAGERSTOWN SICL
13
5.5
2.48
12.5
4.OOOOE+OO
4.0000
0.76
1.6129E+02
WEHADKEE SIL
13
5.6
1.09
10.2
1.9000E+00
1.9000
0.71
1.7431E+02
TOLL FARM HP
8
7.4
11.70
41.0
2.1800E+01
1.8532E+02
TRAWSCOED SICL
8
6.2
3.69
12.0
7.2000E+00
1.9512E+02
KEYPORT SIL
10
5.4
1.21
2.6000E+00
2.6000
0.68
2.1488E+02
GREAT HOUSE S L
8
6.3
12.00
18.0
2.6000E+01
2.1667 E+02
INDIAN HEAD CL
18
7.8
2.34
5.1000E+00
5.1000
0.72
2.1795E+02
ROSEMAUNDE SCL
8
6.7
1.76
14.0
4.8000E+00
2.7273E+02
WEED RES. SL
8
7.1
1.93
11.0
5.5000E+00
2.8497E+02
MELFORT L
18
5.9
6.05
-
3.3000E+01
33.0000
0.67
5.4545E+02
-------
Table A22. Adsorption Isotherm Parameters (K.N.Kq and K^) for Neburon and selected soil properties
compiled from the literature.
Soil Properties Adsorption Parameters
Soil
Article*
pH
O.C.
C.E.C.
No.
(%)
(me/lOOg)
KO
K N
Koc
TOLL FARM HP
8
7.4
11.70
41.0
2.4000E+C2
2.0513E+03
GREAT HOUSE SL
8
6.3
12.00
18.0
3.2500E+02
2.7083E+03
ROSEMAUNDE SCL
8
6.7
1.76
T4.0
5.8000E+01
3.2955E+03
HEED RES. SL
8
7.1
1.93
11.0
7.2000E+01
3.73Q6E+03
TRANSCOED SICL
8
6.2
3.69
12.0
1.3900E+02
3.7669E+03
Table A23. Adsorption Isotherm Parameters (K
,N,Kn and Knr) for p-Chloroan1l1ne and selected soil prop-
ertles compiled from the literature.
Soil Properties
Adsorption Parameters
Soil
Article*
pH
O.C.
C.E.C.
No.
W
(me/100g)
K N
Kpc
HEVERLEE
31
6.4
0.98
16.6
3.8000E+00
3.8000 0.72
3.8776E+02
HEVERLEE
31
6.6
1.44
20.6
5.8000E+00
5.8000 0.67
4.0278E+02
STAVELOT
31
3.9
2.54
5.6
1.2700E+01
12.7000 0.70
5.0000E+02
SOIGNIES
31
3.4
4.67
16.9
3.2900E+01
32.9000 0.69
7.0450E+02
MEERDAEL
31
4.0
3.57
11.7
2.9000E+01
29.0000 0.70
8.1232E+02
-------
Table A24. Adsorption Isotherm Parameters (K,N,Kq arid KoC) for Parathion and selected soil properties
compiled from the literature.
Soil
Soil Properties
Article* pH O.C. C.E.C.
No. {%) (me/lOOg)
Adsorption Parameters
N
K,
oc
SWEENEY SCL 15
HUGO GRAVELLY SL 15
TIERRA CL 15
ELKHORN SL 15
6.3
5.5
6.2
6.0
0.65
0.12
0.33
0.09
2.2160E+01
6.9000E+00
4.0560E+01
1.8190E+01
22.1600 1.02
6.9000 0.99
40.5600 1.06
18.1900 1.04
3.4092E+03
5.7500E+03
1.2291E+04
2.1151E+Q4
Table A25. Adsorption Isotherm Parameters (K.N.Kp and K^) for Phenyl Urea and selected soil properties
compiled from the literature.
Soil Properties Adsorption Parameters
Soil Article* pH O.C. C.E.C.
No. (%) (me/lOOg) KD K N Koc
TRAWSCOED SICL
8
6.2
3.69
12.0
2.2000E+00
5.9621E+01
TOLL FARM HP
8
7.4
11.70
41.0
8.5000E+00
7.2650E+01
RASEMAUNDE SCL
8
6.7
1.76
14.0
1.3000E+00
7.3864E+01
WEED RES. SL
8
7.1
1.93
11.0
1.6000E+00
8.2902E+01
GREAT HOUSE S L
8
6.3
12.00
18.0
1.1100E+01
9.250GE>01
-------
Table A26. Adsorption Isotherm Parameters (K.N.Kq and Kg,.) for Picloram and selected soil properties
compiled from the literature.
Soil Properties Adsorption Parameters
Soil
Article*
No.
pH
O.C.
{%)
C.E.C.
(me/lOOg)
KD
K
N
*oc
ASqtJITH SL
41
7.5
1.02
3.0000E-02
2.9412E+00
REGINA C
41
7.7
2.40
1.0000E-01
4.1667E+0O
INDIAN HEAD L
41
7.8
2.35
1.0000E-01
4.2553E+0Q
WEVBURN OXBdW L
41
6.5
3.72
2.4000E-01
6.4516E+00
WOODCOCK L
26
6,1
4.44
12.9
3.0000E-01
0.3000
0.85
6.7568E+00
MELFORT L
41
5.9
6.05
4.9000E-01
8.0992E+00
MELFORT
2
6.5
6.00
4.9000E-01
8.1667E+00
WEY8URN-OXB0W
2
7.9
3.75
3.1000E-01
8.2667E+00
INDIAN HEAD
2
8.1
2.70
2.3000E-01
8.5185E+0O
ASQUITH SL
2
6.9
1.04
9.0000E-02
*
8.6538E+00
WEYBURN
2
8.2
2.50
2.4000E-01
9.6000E+00
INDIAN HEAD C
2
8.1
2.36
2.4OO0E-01
1.0169E+01
LACOHBE
2
7.9
7.20
7.5000E-01
#
1.0417E+01
KENTWOOD SI
5
6.4
0.92
1.1800E-01
0,1180
0.84
1.2826E+01
ephrata si
5
7.1
0.54
7.0000E-02
0.0700
0.60
1.2963E+01
MINAN L
26
7.3
2.19
24.4
3.0000E-01
0.3000
0.76
1.3699E+01
MINAM L
26
7.0
3.81
28.3
6.0000E-01
0.6000
0.83
1.5748E+01
PALOtfSE SIL
5
5.7
1.38
3.1000E-01
0.3100
0.83
2.2464E+01
WOODCOCK L
26
5.8
2.48
3.6
6.0000E-01
0.6000
0.99
2.4194E+01
PflLOUSE SIL
5
5.7
2.07
•
5.5300E-01
0.5530
0.82
2.6715E+01
LINNE CL
5
7.4
1.38
•
4.0900E-01
0.4090
0.74
2.9638E+01
FIODLET0WN SIL
5
5.6
2.42
•
9.7600E-01
0.9760
0.85
4.0331E+D1
WOODCOCK L
26
5.6
0.92
3.2
4.1000E-01
0.4100
1.02
4.4565E+01
KINNEY C L
26
5.0
2.88
16.1
1.6000E+00
1.6000
1.00
5.5556E+01
KINNEY C L
26
5.2
4.27
6.5
4.6000E+00
4.6000
0.84
1.0773E+02
KINNEY C L
26
5.2
T .44
8.9
2.3000E+00
2.3000
0.93
1.5972E+02
-------
Table A27. Adsprption Isotherm Parameters (K.N.Kp and KqC) for Prometone and selected soil properties
compiled from the literature.
.Soil Properties Adsorption Parameters
Soil
Article*
No.
PH
O.C.
(%)
C.E.C.
(me/lOOg)
kd
K
N
*oc
LAKELAND SL
13
6.2
1.90
2.9
1.OOOOE+OO
1.0000
0.79
5.2632E+01
CUMBERLAND SL
11
6.4
0.69
6.5
5.0000E-01
7.2464E+01
BATES SL
11
6.5
0.80
9.3
6.0000E-01
7.5000E+01
ELDON SL
11
5.9
1.73
12.9
1.3000E+00
7.5058E+01
MENFRO SL
11
5.3
1.38
9.1
1.2000E+00
8.6957E+01
BAXTER CSL
ii
6.0
1.21
11.2
1.7000E+00
1.4050E+02
HAGERSTOWN SICL
13
5.5
2.48
12.5
4.3000E+00
4.3000
o!84
1.7339E+G2
SARPY L
11
7.1
0.75
14.3
1.5000E+00
2.0000E+02
OSWEGO SCL
ii
6.4
1.67
21.0
3.4000E+00
2.0359E+02
LINTONIA LS
n
5.3
0.34
3.2
7.0000E-01
2.0588E+02
CHILLUM SIL
13
4.6
2.54
7.6
5.4000E+00
5.4000
0.84
2.1260E+02
PUTNAM SL
11
5.3
1.09
12.3
2.8000E+00
2.5688E+02
NEWTONIA SL
5.2
0.92
8.8
2.4000E+00
2.6087E+02
CLARKSVILLE GSL
11
5.7
0.80
5.7
2.2000E+00
2.7500E+02
GRUNDY SCL
11
5.6
2.07
13.5
6.3000E+00
3.0435E+02
WAVERLY SL
11
6.4
1.15
12.8
3.8000E+00
3.3043E+02
WEHADKEE SIL
13
5.6
1.09
10.2
3.9000E+00
3.9000
o! 77
3.5780E+02
MARSHALL SCL
11
5.4
2.42
21.3
8.8000E+00
3.6364E+02
SALIX L
11
6.3
1.21
17.9
4.6000E+00
3.8017E+02
KNOX SL
11
5.4
1.67
18.8
6.4000E+00
3.8323E+02
GERALD SL
11
4.7
1.55
11.0
6.OOOOE+OO
3.8710E+02
SUMMIT SC
11
4.8
2.82
35.1
1.1600E+01
4.1135E+02
LINDLEY L
4.7
0.86
6.9
4.7000E+00
5.4651E+02
UNION SL
5.4
1.04
6.8
6.1000E+00
5.8654E+02
LEBANON SL
11
4.9
1.04
7.7
7.8000E+00
7.5000E+02
SHELBY L
11
4.3
2.07
20.1
2.2300E+01
1.0773E+03
WABASH C
11
5.7
1.27
40.3
1.7000E+01
1.3386E+03
MARIAN SL
11
4.6
0.80
9.9
1.4900E+01
1.8625E+03
SHARKEY C
11
5.0
1.44
28.2
5.5200E+01
3.8333E+03
-------
Table A26. Adsorption Isotherm Parameters (K,N,Kq and K^) for Prometryne and selected soil properties
compiled from the literature.
Soil Properties Adsorption Parameters
Soil
Article*
pk
O.C.
C.E.C.
No.
(*)
(me/lOOg)
kd
K
N
Koc
WEHADKEE sil
13
5.6
1.09
10.2
6.2000E-01
0.6200
0.84
5.6881E+01
LAKELAND $L
13
6.2
1.90
2.9
1.9000E+00
1.9000
0.88
1.0000E+02
COBB S
30
7.3
0.34
3.8
6.6000E-01
0.6600
0.77
1.9412E+02
BATES SL
11
6.5
0.80
9.3
1.60OOE+QO
2.0Q00E+02
CUMBERLAND tl
11
6.4
0.69
6.5
1.4000E+00
2.0290E+02
ELD9N SL
11
5.9
1.73
12.9
3.6000E+00
2.0785E+02
MENFRO SL
11
5.3
1.38
9.1
3.3000E+00
2.3913E+02
LIMT0N1A LS
11
5.3
0.34
3.2
9.000QE-01
2.6471E+02
- SOIL 4
32
' »
3.82
26.9
1.0400E+01
2.7225E+02
8 SOIL 5
32
*
13.61
31.2
3.9800E+01
2.9243E+02
OSWEGO SCL
11
6.4
1.67
21.0
5.0000E+00
2.9940E+02
SOIL 2
32
*
1.56
10.3
5.0000E+00
3.2051E+02
SOIL 3
32
•
1.76
22.3
5.7000E+00
3.2386E+02
SOIL 6
32
•
19.98
83.1
6.5400E+01
3.2733E+02
PUTNAM SL
11
5.3
1.09
12.3
3.8000E+00
3.4862E+02
BAXTER CSL
11
6.0
1.21
11.2
4.3000E+00
3.5537E+02
NEWTONIA SL
11
5.2
0.92
8.8
3.5OO0E+OO
3.8043E+02
SARPY L
11
7.1
0.75
14.3
2.9O0OE+OO
3.8667E+02
HAGERSTOWN SICL
13
5.5
2.48
12.5
1.0300E+01
10.3000
o!84
4.1532E+02
GRUNDY SCL
11
5.6
2.07
13.5
9.2000E+00
4.4444E+02
PORT SIC
30
6.3
1.04
17.9
4.9000E+00
4.9000
ol 76
4.7115E+02
KNOX SL
11
5.4
1.67
18.8
8.40OOE+OO
5.0299E+02
HAVERLY SL
11
6.4
1.15
12.8
5.8000E+Q0
5.0435E+02
(Continued)
-------
Table A28. (Continued)
Soil Properties Adsorption Parameters
Soil
Article*
No.
PH
O.C.
(%)
C.E.C.
(me/lOOg)
kd
K
N
Koc
CHILLUM SIL
13
4.6
2.54
7.6
1.2900E+01
12.9000
0.86
5.0787E+02
MARSHALL SCL
11
5.4
2.42
21.3
1.2300E+01
5.0826E+02
SALIX L
11
6.3
1.21
17.9
6.4000E+00
5.2893E+02
GERALD SL
11
4.7
1.55
11.0
9.4000E+00
6.0645E+02
SOIL 1
32
#
0.51
10.6
3.1000E+G0
6.0784E+02
BREWER CL
30
5.8
1.61
13.5
9.9500E+00
9.9500
o!83
6.1801E+02
CLARKSVILLE CSL
11
5.7
0.80
5.7
5.1000E+00
6.3750E+02
UNION SL
11
5.4
1.04
6.8
8.6000E+00
8.2692E+02
KEBABI8 SL
11
4.9
1.04
7.7
9.OOOOE+OO
8.6538E+02
LINDLEY L
11
4.7
0.86
6.9
7.9000E+00
9.1860E+02
SHELBY L
11
4.3
2.07
20.1
2.2100E+01
1.0676E+03
WABASH C
11
5.7
1.27
40.3
1.7300E+01
1.3622E+03
MARIAN SL
11
4.6
0.80
9.9
1.4200E+01
1.7750E+03
COBB
30
5.3
1.21
9.0
2.8900E+01
28.9000
0.79
2.3884E+03
SHARKEY C
11
5.0
1.44
28.2
4.3400E+01
3.0139E+03
-------
Table A29i Adsorption Isotherm Parameters (K,N,Kg and Kq,.) for Propazlne and selected soil properties
compiled from the literature.
Soil Properties Adsorption Parameters
S011
Article*
No.
PH
O.C.
<*)
C.E.C.
(me/lOOg)
Kp
K
N
*oc
LINTONIA LS
11
5.3
0.34
3.2
1.0000E-01
2.9412E+01
LAKELAND SL
13
6.2
1.90
2.9
8s OOOOE-Ql
0.8000
ol 91
4.2105E+01
BATES SL
IT
6,5
0.80
9.3
7.0000E-01
8.7500E+01
SOIL 4
32
#
3.82
26.9
3.5000E+00
9.1623E+01
PUTNAM SL
11
5.9
1.09
12.3
1.1000E+00
1.0092E+02
CUMBERLAND SL
11
6.4
0.69
6.5
7.0000E-01
1.0145E+02
SOIL 6
32
19.98
83.1
2.0500E+01
1.0260E+02
ELDON SL
11
5.9
1.73
12.9
1.8000E+00
1.0393E+02
OSWEGO SCL
11
6.4
1.67
21.0
1.9000E+00
1.1377E+02
GERALD SL
11
4.7
1.55
11.0
1.8000E+00
1.1613E+02
SUMMIT SC
11
4.8
2.82
35,1
3.4000E+00
1.2057E+02
MARSHALL SCL
11
5.4
2,42
21.3
3.OOOOE+OQ
1.2397E+02
MENFRO SL
11
5.3
1.38
9.1
1.8000E+00
1.3O43E+02
SHELBY L
11
4.3
2.07
20.1
2.8000E+00
1.3527E+02
GRUNDY SCL
11
5.6
2.07
13.5
2.8000E+00
1.3527E+02
SOILS
32
•
13.61
31.2
1.9700E+01
1.4475E+02
WEHADKEE SIL
13
5.6
1.09
10.2
1.6000E+00
1.6000
o!99
1.4679E+02
HAGERSTOWN SICL
13
5.5
2.48
12.5
3.7000E+00
3.7000
0.94
1.4919E+02
NEWTONIA SL
11
5.2
0.92
8.8
1.4000E+00
1.5217E+02
BAXTER CSL
11
6.0
1.21
11.2
1.9000E+00
1.5702E+02
SALIX L
11
6.3
1.21
17.9
1.9000E+00
1.5702E+02
(Continued)
-------
Table A29. {Continued)
Soil Properties Adsorption Parameters
Soil
Article*
pH
O.C.
C.E.C.
No.
(%)
(me/lOOg)
K N
Koc
SARPY L
11
7.1
0.75
14.3
1.2000E+00
1.6000E+02
KNOX SL
11
5.4
1.67
18.8
2.7000E+00
1.6168E+02
SOIL 3
32
1.76
22.3
3.0000E+00
1.7045E+02
WAVERLY SL
11
6.4
1.15
12.8
2.0000E+00
1.7391E+02
SOIL 1
32
0.51
10.6
9.0000E-01
1.7647E+02
CHILLUM SIL
13
4.6
2.54
7.6
4.6000E+00
4.6000 o!96
1.8110E+02
SOIL 2
32
1.56
10.3
3.0000E+00
1.9231E+02
LEBANON SL
11
4.9
1.04
7.7
2.0000E+00
1.9231E+02
SHARKEY C
11
5.0
1.44
28.2
3.0000E+00
2.0833E+02
LEBANON SL
11
4.9
1.04
7.7
2.2000E+00
2.1154E+02
UNION SL
11
5.4
1.04
6.8
2.4000E+00
2.3077E+02
WABASH C
11
5.7
1.27
40.3
3.1000E+00
2.4409E+02
LINDLEY L
11
4.7
0.86
6.9
2.2000E+00
2.5581E+02
MARIAN SL
11
4.6
0.80
9.9
2.1000E+00
2.6250E+02
CLARKSVILLE CSL
11
5.7
0.80
5.7
2.1000E+00
2.6250E+02
-------
Table A30. Adsorption Isotherm Parameters (K.N.Kq and KoC) for S1maz1ne and selected soil properties
compiled from the literature.
Soil Properties Adsorption Parameters
soil
Article*
PH
O.C,
C.E.C.
No.
(*)
(me/lOOg)
Kq
K N
^OC
IREDELL C
12
5.6
6.17
20.9
1.5790E+00
2.5592E+01
GREENFIELD SL
4
7.3
2.77
15.8
9.3000E-01
3.3574E+01
PARK GRASS 13D
44
4.7
2.80
1.OOOOE+OO
3.5714E+01
LAKELAND SL
12
6.2
1.88
2.9
6.8200E-01
3.6277E+01
HANFORD SL
4
6.2
1.90
12.4
6.9000E-01
3.6316E+01
MONTALTG C
12
5.9
0.86
8.4
3.1900E-01
3.7093E+01
TIFTON LS
12
4.9
0.56
2.4
2.0800E-01
3.7143E+01
PARK GRASS 13D
44
4.8
1.80
•
7.0000E-01
3.8889E+01
EXETER SL
4
6.7
1.32
12.8
5.6000E-01
4.2424E+01
YOLO SL
4
6.9
2.59
20; 4
1.1200E+01
4.3243E+01
PARK GRASS 13D
44
4.8
4.50
«
2.OOOOE+OO
4.4444E+0I
RAM0NA SL
4
6.7
1.38
10.4
6.1500E-01
4.4565E+01
PARK GRASS 3A
44
7.0
5.60
«
2.5000E+00
4.4643E+01
HANFORD LS
4
7.2
1.27
9i5
5.9000E-01
4;6457E+01
LAKELAND SL
13
6.2
1.90
2.9
9.0000E-01
0.9000 o!?5
4.7368E+01
YOLO SL
4
7.0
2.30
21.2
1.0900E+00
4.7391E+01
BAUTISTA SL
4
7.2
1.03
14.2
4.9000E-01
4.7573E+01
PARK GRASS 13A
44
6.6
2.10
1.OOOOE+OO
4.7619E+01
BROADBALK
44
6.6
1.20
#
6.0000E-01
5.0000E+01
PARK GRASS 3A
44
6.8
2.40
1.2000E+00
5.0000E+01
PARK GRASS 3A
44
6.9
3.60
1.8000E+00
5.0000E+01
GREENFIELD SL
4
6.5
1.38
12.6
6.9000E-01
5.0000E+01
(Continued)
-------
Table A30. (Continued)
Soil Properties Adsorption Parameters
Soil Article* pH O.C. C.E.C.
No. {%) (me/lOOg) KD K N KQC
BROADBALK
44
7.9
1.00
a
5.0000E-01
5.0000E+01
FALLBROOK FSL
4
6.4
2.77
19.7
1.41OOE+OO
5.0903E+01
PARK GRASS 14A
44
6.9
5.50
2.8000E+00
5.0909E+01
PARK GRASS 13A
44
6.5
3.50
1.8000E+00
5.1429E+01
PARK GRASS 13A
44
6.8
6.00
#
3.1000E+00
5.1667E+01
BROADBALK
44
7.5
2.90
1.5000E+00
5.1724E+01
COACHELLA SL
4
7.1
1.03
11.8
5.4000E-01
5.2427E+01
HANFORD SL
4
6.3
2.82
18.1
1.4800E+00
5.2482E+01
INDIO L
4
7.2
1.32
15.1
7.1000E-01
5.3788E+01
RAMONA SL
4
5.9
1.78
15.2
9.7000E-01
5.4494E+01
HANFORD SL
4
6.0
1.38
11.0
7.8000E-01
5.6522E+01
PARK GRASS 3D
44
5.1
5.30
3.0000E+00
5.6604E+01
RAMONA SL
4
6.6
0.51
9.5
2.9000E-01
5.6863E+01
GREENFIELD SL
4
6.4
2.07
16.4
1.1800E+00
5.7005E+01
DOCOR ADOBE CL
4
7.2
2.13
34.6
1.2200E+00
5.7277E+01
PARK GRASS 14A
44
6.9
3.30
1.9000E+00
5.7576E+01
HANFORD SL
4
6.4
1.55
12.4
9.OOOOE-Ol
5.8065E+01
HANFORD LS
4
5.8
1.15
9.6
6.7000E-01
5.8261E+01
BENEVOLA SIC
12
7.7
2.70
19.5
1.5790E+00
5.8481E+01
RUSTON SL
12
5.1
1.05
3.4
6.1800E-01
5.8857E+01
SAN JOAQUIN SL
4
7.2
0.69
8.6
4.1000E-01
5.9420E+01
PARK GRASS 3D
44
5.1
3.10
1.9000E+00
6.1290E+01
BERKLEY SIC
12
7.1
4.63
33.7
2.9360E+00
6.3413E+01
SAN JOAQUIN L
4
5.1
1.44
11.2
9.2000E-01
6.3889E+01
ELKHORN LS
4
6.7
1.67
13.2
1.1000E+00
6.5868E+01
(Continued)
-------
Table A30. (Continued)
Soil Properties Adsorption Parameters
Soil
Article*
No.
pH
O.C.
(%)
C.E.C.
(me/lOOg)
K
N
Koc
PORTERVILLE
ADOBE C
4
7.3
1.90
37.6
1.2700E+00
6.6842E+01
INDIO L
4
7.2
1.21
13.4
8.1000E-01
6.6942E+01
HAGERSTGWN S1CL
12
5.5
2.48
12.5
1.6670E+00
6.7218E+01
BENEVOLA C
12
7.6
1.30
20.1
8.8200E-01
6.7846E+01
YOLO SL
4
7.0
1.32
17.0
9.0000E-01
6.8182E+01
CECIL SC
12
5.3
1.09
3.6
7.47O0E-O1
6.8532E+01
ELKHORN LS
4
7.0
1.27
11.6
8.8000E-01
6.9291E+01
YOLO L
4
5.8
1.61
22.1
1.1200E+00
6.9565E+01
HANFORD LS
4
6.5
0.86
7,5
6.0000E-01
6.9767E+01
EXETER LS
4
5.8
1.50
14.7
1.0700E+QQ
7.1333E+01
PARK GRASS 3D
44
5.3
2.10
1.5000E+00
7.1429E+01
YOLO SL
4
6.9
1.32
17.1
9.6000E-01
7.2727E+01
VISTA LS
4
6.5
0.86
10.0
6.6000E-01
7.6744E+01
PARK-GRASS U/2D
44
3.8
1.80
1.4OOOE+Q0
7.7778E+01
OOSTER SIL
12
4.7
i .31
6.3
1.O24OE+0O
7.8168E+01
YOLO L
4
7.2
1.78
27.4
1.4300E+00
8.0337E+01
VISTA SL
4
6.2
0.75
14.2
6.1000E-01
8.1333E+01
SAN JOAQUIN L
4
6.6
1.15
16.7
9.4000E-01
8.1739E+01
BERKLEY C
12
7.3
0.99
34.4
8.1400E-01
8.2222E+01
PARK GRASS 14A
44
6.9
1.80
1.5000E+00
8.3333E+01
SAN JOAQUIN L
4
5.6
1.15
14.0
9.6000E-01
8.3478E+01
HAGERSTGWN SICL
12
7.5
1.30
8.8
1.G98QE+00
8.4462E+01
GARLAND C
12
7,1
0.65
23.2
5.5600E-01
8.5538E+01
THURL0W CL
12
7.7
1.25
21.6
1.0980E+00
8.7840E+01
PARK GRASS 11/2D
44
3.6
3.30
•
2.9000E+00
8.7879E+01
AIKEN L
4
5.2
2.94
20.6
2.5900E+00
8.8095E+01
YOLO CL
4
7.2
1.27
27.8
1.1500E+00
9.0551E+01
(Continued)
-------
Table A30. (Continued)
Soil Properties Adsorption Parameters
Soil Article* pH O.C. C.E.C.
No. {%) (me/lOOg) KD K N Kot
SAN JOAQUIN CL
4
7.4
1.21
20.8
1.1000E+00
9.0909E+01
BARNES CL
12
7.4
3.98
33.8
3.6210E+00
9.0980E+01
DUNUBA FSL
4
6.2
0.46
6.6
4.2000E-01
9.1304E+01
CHESTER L
12
4.9
1.67
5.2
1.5790E+00
9.4551E+01
ASCALON SCL
12
7.3
0.85
12.7
8.1400E-01
9.5765E+01
VISTA SL
4
6.8
0.69
13.2
6.9000E-01
1.OOOOE+02
PORTERVILLE
ADOBE CL
4
6.4
0.75
18.1
7.5000E-01
1.0000E+02
STERLING CL
12
7.7
0.94
22.5
9.5200E-01
1.0128E+02
CHILLUM SIL
12
4.6
2.54
7.6
2.5760E+00
1.0142E+02
PANOCHEL
4
7.5
0.57
20.2
5.8000E-01
1.0175E+02
TRIPP L
12
7.6
0.86
14.7
8.8200E-01
1.0256E+02
HOVEY ADOBE L
4
6.6
2.25
49.8
2.3300E+00
1.0356E+02
SORRENTO FSL
4
6.9
1.09
16.1
1.1500E+00
1.0550E+02
BAUTISTA LS
4
6.4
0.28
5.5
3.0000E-01
1.0714E+02
PARK GRASS 11/2D
44
3.7
10.90
1.1900E+01
1.0917E+02
TOLEDO SIC
12
5.5
2.80
29.8
3.0640E+00
1.0943E+02
LAS POSAS SL
4
7.3
1.09
11.8
1.2000E+00
1.1009E+02
WEHADKEE SIL
12
5.6
1.11
10.2
1.2500E+00
1.1261E+02
IREDELL SIL
12
5.4
3.04
17.0
3.4750E+00
1.143l£+02
YOLO CL
4
6.8
2.07
31.0
2.3700E+00
1.1449E+02
MANZANITA CL
4
5.9
1.21
13.8
1.4200E+00
1.1736E+G2
YOLO L
4
6.6
1.73
17.8
2.0500E+00
1.1850E+02
BATES SL
11
6.5
0.80
9.3
l.OOOOE+OO
1.2500E+02
SAN JOAQUIN SCL
4
6.1
0.75
16.2
9.50G0E-01
1.2667E+02
VISTA SL
4
6.4
0.86
12.6
1.1000E+00
1.2791E+02
(Continued)
-------
Table A30, (Continued)
Son Properties . Adsorption Parameters
Soil
Article*
No.
pH
O.C,
(%)
C.E.C.
(me/lOOg)
kd
K
N
*0C
CHILLUM SIL
13
4.6
2.54
7.6
3.3000E+00
3.3000
0.84
1.2992E+02
MARIAN SL
11
4.6
0.80
9.9
3.5000E+00
4.3750E+02
WABASH C
11
5.7
1.27
40.3
6.OOOOE+OO
4.7244E+02
SHARKEY C
11
5.0
1.44
28.2
7.0000E+00
4.8611E+02
DUNDEE SICL
12
5.0
0.96
18.1
6.6280E+00
6.9042E+02
CHINO SL
4
7.4
2.36
14.2
3.6000E+01
1.5254E+03
CAdON L
4
6.2
1.27
14.6
1.6500E+00
1.2992E+02
DIABLO SCL
4
6.1
0.69
35.8
9.1000E-01
1.3188E+02
HA6ERST0WN SICL
13
5.5
2.48
12.5
3.3000E+00
3.3000
ol 78
1.3306E+02
SUPERSTITION LS
4
7.2
0.23
5.6
3.1000E-01
1.3478E+02
BELTSVfLLE SIL
12
4.3
1.40
4,2
1.9440E+00
1.39165+02
HYMAN CL
4
6.4
1.78
32.0
2.5200E+00
1.4157E+02
WYMAN L
4
6.6
1.21
15.4
1.7800E+00
1.4711E+02
CROSBY SIL
12
4.8
1.90
11.5
2.8130E+00
1.48O5E+02
STATEN PEATY L
4
6.9
14.00
72.1
2.1200E+01
1.5143E+02
ELDON SL
11
5.9
1.73
12.9
2.9000E+00
1.6744E+02
CUMBERLAND SL
11
6.4
0.69
6.5
1.2000E+00
1.7391E+02
CLARKSVILLE CSL
11
5.7
0,80
5.7
1.4000E+00
1.75OOE+02
MENFRO SL
11
5.3
1.38
9.1
2.5000E+00
1.8116E+02
BRENTWOOD C
4
6.1
1.67
30.8
3.0300E+00
1.8144E+02
BAXTER CSL
11
6.0
1.21
11.2
2.3000E+00
1.9008E+02
TRUCKTON SL
12
7.0
0.25
4.4
4.9400E-01
1.9760E+02
PUtNAM SL
11
5.3
1.09
12.3
2.2000E+00
2.0183E+02
RINCON L
4
5.8
1.78
25.2
3.8300E+00
2.1517E+02
(Continued)
-------
Table A30. (Continued)
Soil Properties Adsorption Parameters
Soil
Article*
No.
pH
O.C.
(%)
C.E.C.
(me/lOOg)
kd
K N
^oc
CHRISTIANA L
12
4.4
0.57
5.6
1.2500E+00
2.1930E+02
COLOMBIA VFSL
4
7.3
0.86
15.0
1.9900E+00
2.3140E+02
YOLO CL
4
6.1
2.13
31.0
4.9500E+00
2.3239E+02
OSWEGO SCL
11
6.4
1.67
21.0
3.9000E+00
2.3353E+02
COLUMBIA CL
4
6.8
1.38
26.5
3.2300E+00
2.3406E+02
YOLO L
4
7.3
1.03
24.0
2.5300E+00
2.4563E+G2
SHELBY L
11
4.3
2.07
20.1
5.1000E+00
2.4638E+02
WEHADKEE SIL
13
5.6
1.09
10.2
2.7000E+00
2.7000 0.76
2.4771E+02
NORFOLK SL
12
5.1
0.08
0.2
2.0800E-01
2.6000E+02
SHARKEY C
12
6.2
2.25
40.2
5.8700E+00
2.6089E+02
SARPY L
11
7.1
0.75
14.3
2.0000E+00
2.6667E+02
LEBANON SL
11
4.9
1.04
7.7
2.8000E+00
2.6923E+02
WAVERLY SL
11
6.4
1.15
12.8
3.1000E+00
2.6957E+02
GERALD SL
11
4.7
1.55
11.0
4.2000E+00
2.7097E+02
SUMMIT SC
11
4.8
2.82
35.1
7.9000E+00
2.8014E+02
SALIX L
11
6.3
1.21
17.9
3.5000E+00
2.8926E+02
LINTONIA LS
11
5.3
0.34
3.2
1.OOOOE+OO
2.9412E+02
MARSHALL SCL
11
5.4
2.42
21.3
7.2000E+00
2.9752E+02
LINDLEY L
11
4.7
0.86
6.9
2.6000E+00
3.0233E+02
KNOX SL
11
5.4
1.67
18.8
5.1000E+00
3.0539E+02
BOSKET SIL
12
5.8
0.57
8.4
1.7570E+00
3.0825E+02
GRUNDY SCL
11
5.6
2.07
13.5
6.5000E+00
3.1401E+02
NEWTONIA SL
11
5.2
0.92
8.8
3.OOOOE+OO
3.2609E+02
UNION SL
11
5.4
1.04
6.8
3.8000E+00
, ,
3.6538E+02
-------
Tdble A31, Adsorption Isotherm Parameters (K.N/Ko and *oc) for Terbacll and selected soil properties
compiled from the literature.
Soil Properties Adsorption Parameters
son
Article*
PH
O.C.
C.E.C.
No.
(«)
(me/IOOg)
kd
K
N
Kpc
EUSTIS
42
5.6
0.56
5.2
1.2060E-01
0.1200
0.88
2.1429E+01
CECIL LS
10
5.8
0.40
1.5000E-01
0.1500
0.96
3.7500E+01
CECIL
42
5.6
0.90
6.8
3.8000E-01
0.3800
0.99
4.2222E+01
WEBSTER
42
7.3
3.87
54.7
2.4600E+Q0
2.4600
0.88
6.3566E+01
KEYPORT SIL
10
5.4
1.21
» '
1.7000E+00
1.7000
0.50
1.4050E+02
Table A32. Adsorption Isotherm Parameters (K.N.Kq and KqC) for Thlmet and selected soil properties
compiled from the literature.
Soil
Soil Properties
Article* piT 6~CT C.E.C.
No. (*) (me/IOOg)
*D
Adsorption Parameters
N
*oc
HUGO GRAVELLY SL 15
SWEENEY SCL 15
ELKHORN SL 15
TIERRA CL 15
5.5
6.3
6.0
6.2
0.12
1.65
0.09
0.33
1.9600E+00
1.3710E+01
3.9400E+00
1.5500E+0T
1.9600 0.93
13.7100 1.01
3.9400 0.94
15.5000 1.00
1.6333E+03
2.1092E+03
4.5814E+03
4.6970E+03
-------
Table A33. Adsorption Isotherm Parameters (K.N.Kq and Y^c) for trans-telone and selected soil properties
compiled from the literature.
Soil Properties
Adsorption Parameters
Soil
Article*
PH
O.C.
C.E.C.
•No.
(*)
(me/lOOg) Kq
K
N
Koc
PEATY S
22
10.39
7.7000E+01
7.4110E+02
HUMUS S
22
3.17
2.4000E+01
7.5710E+02
PEATY S
22
10.39
1.3000E+02
1.2512E+03
HUMUS S
22
3.17
4.0000E+01
1.2618E+03
PEATY S
22
10.39
2.2000E+02
2.1174E+03
HUMUS S
22
3.17
6.8000E+01
2.1451E+03
Table A34.
Adsorption Isotherm Parameters
K,N,Kp and KoC) for Trithion
and selected soil
properties
compiled from the
literature.
Soil Properties
Adsorption Parameters
Soil
Article*
PH
O.C.
C.E.C.
No.
<*)
(me/lOOg) KD
K
N
Kpc
SWEENEY SCL
15
6.3
0.65
5.4560E+01
54.5600
0.88
8.3938E+G3
TIERRA CL
15
6.2
0.33
9.8650E+01
98.6500
0.88
2.9894E+04
HUGO GRAVELLY SL 15
5.5
0.12
6.2800E+01
62.8000
1.00
5.2333E+04
ELKHORN SL
15
6.0
0.09
8.2300E+01
82.3000
1.00
9.5698E+04
-------
Table A35. Adsorption Isotherm Parameters (K,N,Ko and KoC) for 2,4-D acid and selected soil properties
compiled from the literature.
Soil Properties Adsorption Parameters
Soil
Article*
No.
PH
O.C.
(*)
C.E.C.
(me/IOOg)
*0
K
N
*oc
REGINA HC
17
7.7
2.39
1.9Q00E-Q1
7.2200
7.9498E+Q0
HEYBURN OXBOW L
17
6.5
3.72
4.5000E-01
0.4500
1.05
1.2097E+01
REGINA C
41
7.7
2.40
3.1000E-01
#
1.2917E+Q1
ASQUITH SL
41
7.5
1.02
1.4000E-01
#
1.3725E+01
HELFORT L
17
5.9
6."05
9.9000E-01
0.9900
i!oo
1.6364E+01
WEYBURN OXBOW L
41
6.5
3.72
6.1000E-01
#
1.6398E+01
INDIAN HEAD L
41
7.8
2.35
4.4000E-01
. m
1.8723E+01
INDIAN HEAD L
17
7.8
2.34
5.3000E-01
0.5300
0* 97
2.2650E+01
MELF0RT L
41
5.9
6.05
3.3800E+00
•
5.5868E+01
-------
Table A36. Adsorption Isotherm Parameters (K,N,Kq and KqC) for 2,4-D amine and selected soil properties
compiled from the literature.
Soil
Soil Properties
Article* pH O.C. C.E.C.
No. (%) (me/lOOg)
KD
Adsorption Parameters
N
Kqc
CECIL
WEBSTER
EUSTIS
42
42
42
5.6
7.3
5.6
0.90
3.87
0.56
6.8
54.7
5.2
6.5000E-01
4.6200E+00
7.6000E-01
0.6500 0.83
4.6200 0.70
0.7600 0.73
7.2222E+01
1.1938E+02
1.3571E+02
Table A37. Adsorption Isotherm Parameters (K,N,Kq and K^) for 2,4,5-T and selected soil properties
compiled from the literature.
Soil
Article*
No.
PH
Soil Properties
O.C.
m
C.E.C.
(me/lOOg)
KD
Adsorption Parameters
K
N
H)C
EPHRATA SL 35
ORDINANCE SL 35
GLENDALE SICL 35
PALOUSE SIL 35
7.5
6.6
8.5
6.5
0.80
3.66
0.53
2.43
3.1000E-01
2.4000E+00
4.9000E-01
3.0000E+00
3.8750E+01
6.5574E+01
9.2453E+01
1.2346E+02
-------
Table A38. Adsorption Isotherm Parameters (K,N,Kp and K^) for Denobll and selected soil properties
compiled from the literature.
Soil Properties Adsorption Parameters
Soil Article* pH O.C. C.E.C.
No. (*) (me/lOOg) Kq K N Kqc
CROGHAN LFS
21
4.2
3.75
2.2O0OE+QO
5.8667E+01
CROGHAN LFS
21
.4.4
1.73
1.6000E+00
9.2379E+01
CAMRODEN SIL
21
4.6
1.15
1.1000E+00
9.5652E+01
EMPEYVILLE Sit
21
4.5
4.33
4.5000E+00
1.0393E+02
LACKAWANNA SIL
21
4.6
5.54
6.0000E+00
1.0830E402
COVINGTON SIC
21
5.7
5.30
6.7000E+00
1.2642E+02
CAMRODEN SIL
21
4.6
4.73
6.60G0E+00
1.3953E+02
CROGHAN LFS
21
5,7
2.65
3.7000E+00
1.3962E+02
EMPEYVILLE SIL
21
4.9
5.54
7.8000E+00
1.4079E+02
CROGHAN LFS
21
4.6
0.28
4.0000E-Q1
1.4286E+02
HOWARD GRL
21
4.6
3.06
4.4000E+00
1.4379E+02
AMENIA SIL
21
6.2
3.34
5.0000E+00
1.4970E+02
HARDIN SIL
21
5.9
2.88
4.5000E+00
1.5625E+0?
VERGENNES SIL
21
4i6
2.80
4.5000E+00
1.6O71E+02
TROY GRSIL
21
3.8
2.42
3.9000E+00
1.6116E+02
VERGENNES C
21
4.8
2.54
4.I000E+00
1.6142E+02
LIMA GRSI
21
6.3
2.59
4.2000E+00
1.6216E+02
EMPEYVILLE SIL
21
4.5
1.04
1.7000E+00
1.6346E+02
WILLIAMSON SIL
21
3.9
2.54
4.3000E+00
1.6929E+02
GRANBY FSL
21
6.8
3.00
5.1000E+00
1.7OOOE+02
SODUS GRL
21
4.8
3.06
5.3000E+00
1.7320E+02
VERGENNES SIL
21
4.6
0.75
1.3000E+00
1.7333E+02
VERGENNES SIL
21
5.9
0.75
1.3000E+00
1.7333E+02
(Continued)
-------
Table A38. (Continued)
Soil Properties Adsorption Parameters
Soil Article* pH~~ OTcT^ C.E.C.
No. (%) (me/lOOg) KD K N Kpc
AMENIA SIL
21
6.4
0.69
1.2000E+00
1.7391E+02
VERGENNES SIL
21
4.9
0.34
6.OOOOE-Ol
1.7647E+02
COLONIE LFS
21
5.0
0.92
1.9000E+00
2.0652E+02
COVINGTON SIC
21
6.5
0.57
1.3000E+00
2.2807E+02
CROGHAN LFS
21
4.8
0.11
3.OOOOE-Ol
2.6087E+02
COVINGTON SIC
21
6.7
0.40
1.3000E+00
3.2500E+02
AMENIA SIL
21
7.1
0.28
1.2000E+00
4.2857E+02
EMPEYVILLE SIL
21
4.6
0.17
9.OOOOE-Ol
5.2023E+02
CROGHAN LFS
21
4.6
0.11
6.OOOOE-Ol
5.2174E+02
AMENIA SIL
21
7.4
0.11
8.OOOOE-Ol
6.9565E+02
CAMRODEN SIL
21
5.6
0.23
1.9000E+00
8.2609E+02
-------
Table A39. Article number used 1n Table A1-A38 and the corresponding
literature citation.
Article No.
Article No
•
Used In
used in
Tables
Reference
Tables
Reference
1
Graham-Bryce, 1967
24
Konrad and Chesters, 1969
2
Grover, 1971
25
McGlamery and Slife, 1966
3
Grover, 1974
26
Gaynor and Voile, 1976
4
Day et al., 1966
27
Bumside and Lavy, 1966
5
Farmer and Aochi, 1974
28
Geissbuhler et al., T963
6
Liu et al., 1970
29
Hance, 1967
7
Grover and Hance, 1969
30
Murray et al., 1975
8
Hance, 1965
31
van Bladel and Noreale, 1977
9
Schliebe et al., 1965
32
Walker and trawford, 1970
10
Rhodes et al., 1970
33
Funni dge and Osgerby». 1,9.67
11
Talbert and FletchalT, 1965 34
Talbert et alV i 1964
12
Harris and Sheets, 1965
35
O'Connor and Anderson, 1974
13
Harris, 1966
36
Wlldung et al., 1968
14
Haron et al., 1967
37
Koren et al., 1969
15
King and McCarty, 1967
38
Obien and Green, 1969, and
16
Colbert et al., 1975
Green and Obien, 1969
17
Grover and. Smith, 1974
39
Kay and Elrick, 1967
18
Grover, 1975
40
Maj.ka and Lavy, 1977
19
Dao and Lavy, 1978
41
Grover, 1977
20
McNamara and Toth, 1970
42
Rao and Davidson, 1979
21
Briggs and Dawson, 1970
43
Robert and Wilson, 1965
22
Liestra, 1970
44
Williams, 1968
23
Shim et al., 1970
45
Jamet and Pledallu, 1975.
199
-------
APPENDIX B
Tables of Pesticide Transformation Rate Coefficients
200
-------
Table Bl. Solvent extractable 2,4-D disappearance rates in laboratory Incubated soils under aerobic
conditions.
ki
(day-1)
Concentration
(pg/g)
pH
0M
<*')
C1<8
Temp
(°G)
Soil-water
Content
(X)
Reference
1.4*10-1
4.79
„
3.3
15.5
22
Altom and Strltzke,
1973
1.7x10-1
4.79
—
2.8
16.5
22
--
Ibid
1.7x10-1
4.79
—
3.8
18.5
22
—
Ibid
Z.8itl0-?
2.5
7.2
1.91
12.6
26
6.9
Foster and McKercher, 1973
3.1x10"
2.5
7.6
3.36
15.0
26
10.0
Ibid
7.7x10-2
2.5
7.8
1.84
54.5
22
16.7
Ibid
5.6x10-2
2.5
6.2
6.78
53.0
26
16.1
Ibid
5.2*10-2
2.5
7.5
2.85
25.0
26
15.0
Ibid
3.9*10-2
2.5
7.6
2,38
24.5
26
11.9
Ibid
2.4*10-|
2.5
7.2
1.91
12.6
26
13.8
Yoshlda and Castro,
1975
2.2*10"2
2.5
7:6
3.36
15.0
26
20.0
Ibid
6.7*10"?
2.5
7.8
1.84
54.5
26
33.4
Ibid
5.3*10"2
2.5
6.2
^6.78
53.0
26
32.1
Ibid
5.1*10-2
2.5
7.5
2.85
25.0
26
29.9
Ibid
3.4x10-2
2.5
7.6
2.38
24.5
26
23.8
Ibid
7.9x10-2
20
6.6
2.0
...
30
80% of FC*
Yoshlda and Castro,
1975
2.1*IQ-2
20
4.7
3.2
•T ¦
30
802 of FC*
Ibid
*FC is "field-capacity" soil-water content.
-------
Table B?. Solvent extractable 2,4-D disappearance rates in the field.
Soil-water
Iq Concentration pH GM Clay Temp Content Depth Reference
(day-1) (kg/ha) (%) {%) (°C> (%) (cm)
6.4x10-2 4.5
0-5 Radosevich and Winterlin,
1977
9.6x10*2
7.8
5.8
2.6
25
5.3
—
0-10
Stewart and Gaul,
4.6x10-2
15.7
5.8
2.6
25
5.3
—
0-10
Ibid
7.0x10-2
31.4
5.8
2.6
25
5.3
—
0-10
Ibid
1.0x10*1
5.5
5.8
2.6
25
5.3
—
0-10
Ibid
8.3x10-2
11.2
5.8
2.6
25
5.3
—
0-10
Ibid
6.5xl0-2
22.4
5.8
2.6
25
5.3
—
0-10
Ibid
4.5x10-1
11.2"
5.6
2.9
26
13.5-23
12.5-23.3
0-24
Wilson and Cheng,
>0.7
11.2
5.6
2.9
26
13.5-23
12.5-23.3
0-24
Ibid
>0.7
1.1
5.6
2.9
26
13.5-23
12.5-23.3
0-24
Ibid
>0.7
1.1
5.6
2.9
26
13.5-23
12.5-23.3
0-24
Ibid
2.2x10*1
11.2
5.6
2.9
26
13.5-23
12.5-23.3
0-24
Ibid
-------
Table B3. Mineralization rates of 14c-ring labeled 2,4-D In soils under aerobic conditions.
Soil-water
ki Concentration pH OM Clay Temp Content Reference
(day-1) (ng/g) (X) (.*') (°C) (%)
4.7x10-2
2.8*10-2
5.2x10-2
6.5x10-2
6.3x10-2
5.8x10"?
50
7.3
3.9
18.4
23
30
Ou, et al., 1978
50
7.3
3.9
18.4
23
30
Ibid
1.6
5.6
3.2
25
25
22
Wilson and Cheng,
1.6
5.6
3.2
25
25
22
Ibid
16
5.6
3.2
25
25
22
Ibid
16
5.6
3.2
25
25
22
Ibid
-------
Table B4. Solvent extractable 2,4,5-T disappearance rates in soils incubated in the laboratory under
aerobic conditions.
kl .
(day-1)
Concentration
(pg/g) ;
pH
OM
(*>
Clay
(%)
Temp
(°c)
Soil-water
Content
(*)
Reference
2.9x10-2
4.79
3.3
15.5
22
Altom and Stritzke, 1973
5.0x10-2
4.79
--
2.8
16.5
22
Ibid
3.3x10-2
4.79
—
3.8
18.5
22
Ibid
1.2x10-2
2.5
7.5
2.38
24.5
26
23.8
Foster and McKercher, 1973
3.9x10-2
10
6.6
2.0
_ _ •
_ _
Yoshida and Castro, 1975
1.1x10-2
10
4.7
3.2
Ibid
ro
o
-c*
-------
Table B5. Solvent extractable 2,4-5-T disappearance rates under field conditions.
ki Concentration pH
(day-1) (kg/ha)
OM
(*)
Clay
(?)
Temp
(°C)
Soil-water
Content
i%)
Depth
(an)
Reference
7.4*10-?
4.5
—
—
—
—
--
0-5
Radosevlch and W1nterl1n, 1977
4.0X10-Z
7.8
5.8
2.6
25
5.3
0-10
Stewart and Gaul, 1977
1.5x10-2
15.7
5.8
2.6
25
5.3
0-10
Ibid
9.9xlQ-3
31.4
5.8
2.6
25
5.3
••
0-10
Ibid
-------
Table B6. Solvent extractable atrazine disappearance rates under field conditions.
Soil-water
ki Concentration PH GM Clay Temp Content Depth Reference
(dayl) (kg/ha) (*) (%) (°C) (%) (cm)
3.8x10-2
1.1
6.3
2.2
30.8
25.8
0-15
Hall and Hartwig, 1978
3.4xl0-2
2.2
6.3
2.2
30.8
25.8
0-15
Ibid
2.7x10-2
4.5
6.3
2.2
30.8
25.8
0-15
Ibid
4.8x10-2
9.0
6.3
2.2
30.8
25.8
0-15
Ibid
1.3x10-2
4.5
5.3
1.8
--
—
—
Khan and Marriage, 1977
4.4x10-2
2.24
_ _
_ -
_ — —
Sikka and Davis, 1966
5.0x10-2
2.24
--
—
—
—
Ibid
5.0x10-2
2.24
--
--
—
—
—
Ibid
5.8x10-2
4.48
--
—
--
—
—
Ibid
5.8x10-2
4.48
--
—
--
—
¦ —
Ibid
3.7x10-2
4.48
—
--
—
—
Ibid
4.4x10-2
17.92
--
--
—
—
Ibid
5.7x10-2
17.92
--
—
—
—
—
Ibid
5.3x10-2
17.92
—
—
—
Ibid
2.2x10-2
4.5
5.3
1.8
7.6
17.6(Ave.) —
0-15
Marriage, et al., 1975
-------
Table E}7. Solvent extractable simazlne disappearance rates 1n the field.
ki
(day-1)
Concentration
(kg/ha) pH
OM
{%)
Clay Temp
(«) (°c)
Depth
(cm)
Reference
2,1x10"?
4.5
5.3
1.8
7.6 17.6 (Ave.)
0-15
Marriage, et al., 1975
1.1x10-2
2.8
7.9
5.1
16 ' —
0-23
Clay, 1973
1.1x10-2
5.6
7.9
5.1
16
0-23
Ibid
2,8x10-2
52.4
7.9
5.1
16 —
0-23
Ibid
6.2x10-2
0.5
0-15.2
Joshl and Oatta, 1975
5.9Xl0i
1.0
* •
--
0-15.2
Ib1 d
5.5x10-2
1.5
' «
' r - (
' -/¦ . • '
0-15.2
Ibid
7.6x10-3
0.45
7J
3.0
61.5
0-20
Roadhoiise and Blrk, 1961
1.1x10-2
0.9
7.1
3.0
61.5
0-20 '
Ibid
1.5x10-2
1.8
7.1
3.0
61.5 —
0-20 S
Ibid
1.3x10-2
5.4
7.1 :
3.0
61.5 :. . « . ;'
0-20 .
Ibid
1.1x10-2
6.9
7.1
3.0
61.5
0-20 j
Ibid
1.0x10-2
17.8
7.1
3.0
61.5 —
6-20 |
Ibid
-------
Table B8. Solvent extractable atrazine disappearance rates in soils incubated in the laboratory under
aerobic conditions.
Soil-water
ki Concentration pH OM Clay Temp Content Reference
(dayl)
-------
Table B9. Solvent extractable slmazlne disappearance rates In soils under aerobic laboratory
incubation.
Iq Concentration pH OM
(day-1) (ug/g) (%)
CI a
8
Temp
CC)
So11-water
Content
(*)
Reference
6.3x10-3
0.67
7.3
2
20
--
Beynon, et al
1.9x10-2
8
7
2
18
25
13.2
Weilker, 1976a
1.5x10-2
8
7
2
18
25
10.7
Ibid
1.3x10-2
8
7
2
18
25
9.7
Ibid
1.1x10*2
8
1
2
18
25
7.9
Ibid
9^0x10-3
8
7
2
18
25
6.0
Ibid
8>2xl0-3
8
7
2
18
25
4.8
Ibid
6.2xl0-|
8
7
2
18
15
11.5
Ibid
3.0x10-3
8
7
2
18
15
6.6
Ibid
1.8x10-2
4
7
2
18
25
11.2
Ibid
3.3x10-3
4
_ _ ¦
5
4.
Walker, 1976b
5,0x10-?
4
--
id
4
Ibid
7.5x10-3
4
•
—
15
4
Ibid
1.2x10-?
4
--
—
20
4
Ibid
1.7x10-2
4
--
-r-
r?—
25
4
Ibid
2.4x10-2
4
—
30
4
Ibid
2.5x10-2
4
25
8
I bid
5.5x10-3
4
--
--
--
5
12
Ibid
8.7x10*3
4
--
10
12
Ibid
i;3xi6-2
--
--
IS
12
Ibid
2.0x10*2
--
--
20
12
Ibid
7.0x10-3
8
_ —
»•>
13.2
40% FC
Zlmdahl, et a
1.8x10-2
8
r- '
31.2
401 FC
Ibid
-------
Table BIO. Mineralization rates in soils from ring-labeled l^c-atrazine under aerobic conditions.
Soil-water
k-| Concentration pH OM Temp Content Reference
(day-1) (ng/g) (%) (°C) (%)
2.0xl0"4
6.7x10-6
4.6xl0-5
9.2xl0-5
10
4.7
10.5
24.5
67
Goswami and Green- 1971
10
6.4
3.4
24.5
67
Ibid
2.58
6.8
3.1
27
54.2
Skipper and Volk, 1972
2.58
6.6
3.1
27
32.1
Ibid
-------
Table Bll. Solvent extractable trlfluralin disappearance rates 1n soils Incubated 1n the laboratory
under aerobic conditions.
kl
(day-1)
Concentration
(vg/g)
PH
OM
(*)
Clay
(%)
Temp
(°C)
Soil-water
Content
(%)
Reference
4.4X10-3
10
5.3
1.5
12.2
70* FC
Kearney, et al., 1976
7.5x10-3
5
6.0
--
—
25
100% FC
Parr and Smith, 1973
8.1X10"3
8
—
--
--
25
50% FC
Probst, et al., 1967
8.8x10-3
8
—
--
--
25
1003! FC
ibid
1.8xl0-3
7.85
7.6
1.6
14
15
80% FC
Zimdahl and Gwynn, 1977
7.7x10-3
7.85
7.6
1.6
14
3d
80% FC
Ibid
2.5x10-3
7.85
6.6
2.2
20
15
802 FC
Ibid
9.2x10-3
7.85
6.6
2.2
20
30
80% FC
Ibid
1.3x10-2
7.85
7.6
1.6
14
30
80% FC
Ibid
2.1x10-2
7.85
6.6
2.2
20
30
80% FC
Ibid
-------
Table B12. Solvent extractable trifluralin disappearance rates in soils incubated in the
laboratory under anaerobic conditions.
Soil-water
ki Concentration pH Temp Content Reference
(day-1) (gg/g) (°C) (%)
9.9x10-3
5
6.0
25
100%
FC
Parr and Smith,
1973
2.0xl0-2
8
--
4
200%
FC
Probst, et al.,
1967
2.0X10'1
8
--
25
200%
FC
Ibid
6.9x10-2
8
--
25
200%
FC
Parr and Smith,
1973
-------
Table B13. Solvent extractable trlfluralln disappearance rates in the field.
*1
(dajr-1)
Concentration
(kg/ha)
PH
OH
(*)
Clay
.(*)
Temp
(°C)
Soil-water
Content
(it)
Depth
(cm)
Reference
1.26
6.0
1.33
22.9
22(Ave)
—
0-30
Duseja and Holmes, 1978
2.7x70"2
1.26
5.9
1.90
40.4
22(Ave)
--
0-30
Ibid
2.1*70~Z
1.1
8.1
0.8
16
--
13
0-2.5
Menge and Tamez, 1974
7.8xlO*2
1.1
8.1
0.8
76
—
13
0-7.5
Ibid
4.7xl
-------
Table B14. Solvent extractable bromacil disappearance rates in soils
incubated in the laboratory under aerobic conditions.
kl .
(day-T)
Concentration
(yg/g)
Temp
(°C)
Soil-water
Content
(*)
Reference
1.2xl0-2
10
Gardiner, et al., 1969
4.5x10"3
8
13.2
40% FC
Zimdahl, et al., 1970
6.3xl0-3
8
31.2
40% FC
Ibid
214
-------
Table 615. Solvent extractable terbacil disappearance rates In soils
incubated in the laboratory under aerobic conditions.
ki
(day!)
Concentration
(ug/g)
Temp
CC)
Soil-water
Content
.(*).
Reference
1.2xl0-2
2.25
Gardiner, et al., 1969
•WZxlO-2
8
13.2
401 FC
Zimdahl, et¦al., 1970
2.0x10-2
8
31.2
40% FC
Ibid
215
-------
Table B16. Mineralization for bromaci] in soils under aerobic conditions.
*1
(day*!)
Concentration
(vg/g)
Reference
4.6x10'3
10
Gardiner, et al., 1969
4.2x1CH
2.88
Wolf and Martin, 1974
216
-------
Table B17. Mineralization rates for terbacil in soils under aerobic
conditions..
ki
(day1)
Concentration
(v9/g)
Reference
8.5x10-3
2.25
Gardiner, et al., 1969
5.4xl0"4
2.88
Wolf and Martin, 1974
217
-------
Table BIO. Solvent extractable bromacil disappearance rates in the field.
I<1
(day-1)
Concentration
(kg/ha)
PH
OM
(*>
Clay
(%)
Depth
(cm)
Reference
1.1x10-2
4.48
0-30.5
Gardiner, et al., 1969
4.0x10-3
4.48
0-30.5
Ibid
1.5xl0-3
1.6
3.7
2.3
7.2
0-140
Leistru, et al., 1975
8.7x10-4
2.4
3.7
2.3
7.2
0-140
Ibid
3.9xl0-3
1.6
5.5
3.1
36.9
0-140
Ibid
1.6x10-3
2.4
5.5
3.1
36.9
0-140
Ibid
-------
Table BT9. Solvent extractive terbacll disappearance rates In the field.
Soil-water
ki Concentration pH OM Clay Temp Content Depth Reference
(day-lj (kg/ha) («) (*} (°C) (*) (cm)
9.2x10-3
4.48
6-30.5
Gardiner, et al., 1969
5.3X10"3
4.48
0-30.5
Ibid
1,7x10*3
4i5
0-5
Khan, 1977
7.8x10-3
4.6
0-15
Ibid
-------
Table B20. Solvent extras table linuron disappearance rates in soils incubated in the laboratory
under aerobic conditions.
ki
(day1)
Concentration
Jtug/g)
pH
0M
{%)
Clay
(%)
Temp
(°C)
Soil-water
Content
{%)
Reference
8.0xl0~3
4
7.3
1.45
15
20
16.7
Hance,
1974
8.9xl0-3
10
7.3
2.5
15
20
20
Moyer,
et al., 1972
2.4xl0~3
10
6.9
4.3
27.2
4
0.25 WHC(FC)
Usorol
and Hance, 1974
2.5xl0~3
10
6.9
4.3
27.2
4
0.5 WHC(FC)
Ibid
3.7xlO~3
10
6.9
4.3
27.2
4
1 WHC(FC)
Ibid
7.9xl0~3
10
6.9
4.3
27.2
22
0.25 WHC(FC)
Ibid
l.lxlO-2
10
6.9
4.3
27.2
22
0.5 WHC(FC)
Ibid
1.2xl0"2
10
6.9
4.3
27.2
22
1 WHC(FC)
Ibid
-------
Table B21. Solvent extractable Unuron disappearance rates 1n the field.
k.1
(day-l)
Concentration
(kg/ha)
PH
QM
(%)
Clay
(%)
Temp
<°C)
Soil-water
Content
(%)
Depth
(cm)
Reference
2.8xl0"3
2.2
7.3
4
69
--
—
0-5
Smith and Edmond, 1975
5.2x10"3
2.2
6.7
3
6
—
--
0-5
Ibid
2.0X10"3
2.2
5.6
3
9
—
--
0-5
Ibid
3.&X10"3
2.2
5.6
3
9
f.-
0-5
Ibid
-------
Table B22. Solvent extractable diuron disappearance rates in the field.
k] Concentration OM Clay Temp Depth
(day-1) (kg/ha) (8) {%) (CC) (cm) Reference
5.0x10"^ 1.12 -- — — 0-10 Hill, et al., 1955
4.2x10-3 1.12 — — — 0-10 Ibid
5.2xl0"3 1.12 — — — 0-10 Ibid
3.3xl0-3 2.24 — — — 0-10 Ibid
5.0xl0-3 2.24 -- — — 0-10 Ibid
1.3x10-3 4.5 1.1 5.1 9 0-15 Khan, et al., 1976
1.3x10-3 4.5 i.i 5.1 9 0-15 Ibid
rv>
ro
ro
-------
Table B23. Solvent extractable dlcamba disappearance rqtes 1ri soils Incubated In the laboratory under
aerobic conditions.
Soil-water
ki Concentration pH ON Clay Temp Content Reference
(day-1) (»g/g) {%) (S) (•€) (%)
2.2x10^2
2.2x10-2
4.lxiq-2
2.0x10-2
2.1x10"]
2.1x10^
5.3x10-2
7.3x10**
9.0*10-2
3.0xlOi
2.4x10*2
1.3x10-2
6.0x10-2
1.5x10"]
1.5x10"]
2.5*10~]
2.5x10"'
2.47
--
3.3
15.5
22
--
Altom and Strltzl
2.47
—
2.8
16.5
22
—
Ibid
2.47
—
3.8
18.5
22
—
Ibid
2
7.5
3.2
6
25
5
Smith, 1973
2
7.5
3.2
6
25
10
Ibid
2
5.2
H.7
30
25
20
Ibid
2
7.7
4.2
69
25
25
Ibid
2
7.7
4.2
69
25
30
Ibid
2
7.7
4.2
69
25
35
Ibid
2
5.2
11.7
30
25
28
Ibid
2
5.2
11.7
30
25
35
Ibid
3.5
7.7
4.2
69
25
40* FC
Smith, 1974
2.8
7.7
4.2
69
25
401 FC
Ibid
2
5.2
11.7
30
6
361 FC
Smith and CulHro
2
5.2
11.7
30
10
3631 FC
Ibid
2
5.2
11.7
30
15
36* FC
Ibid
I
5.2
11.7
30
20
36% FC
Ibid
2
5.2
11,7
30
30
36% FC
Ibid
2
5.2
11.7
30
40
36% FC
Ibid
(Continued)
1975
-------
Table B23. (Continued)
Soil-water
ki Concentration pH GM Clay Temp Content Reference
(day-1) (yg/g) (%) (%) (°C) (%)
~0
1.8xl0-2
6.5x10-2
9.6x10-2
2.5x10-2
1.6x10-2
9.5x10-3
2.8x10-2
3.8x10-2
7.3x10-2
1.9x10-1
1.9x10"'
2
7.5
3.2
6
6
11% FC
Smith and Cullim
2
7.5
3.2
6
10
11% FC
Ibid
2
7.5
3.2
6
15
11% FC
Itiid
2
7.5
3.2
6
20
11% FC
Ibid
2
7.5
3.2
6
30
11% FC
Ibid
2
7.5
3.2
6
40
11% FC
Ibid
2
7.7
4.2
69
6
40% FC
Ibid
2
7.7
4.2
69
10
40% FC
Ibid
2
7.7
4.2
69
15
40% FC
Ibid
2
7.7
4.2
69
20
40% FC
Ibid
2
7.7
4.2
69
30
40% FC
Ibid
2
7.7
4.2
69
40
40% FC
Ibid
-------
Table B24. Solvent extractable dicamba disappearance rates in the field.
k]
(day-*l)
Concentration
(kg/ha)
PH
OM
(%)
Clay
(?)
Temp
(9C)
Depth
(cm)
Reference
1.1x10-1
1.0x10"!
9.5XT0-2
1.0x10-1
0.28
0.56
0.28
0.56
6.94
6.94
6.45
6.45
0.81
0.81
2.35
2.35
17
17
45
45
—
0-15
0-15
0-15
0-15
Sclfres and Allen, 1973
Ibid
Ibid
Ibid
7.7x10-z
7.2x10*2
1.1
2.2
5.8
5.8
2.6
2.6
25
25
5.3
5.3
0-10
0-10
Stewart and Gaul, 1977
Ibid
-------
Table B25. Solvent extractable picloram disappearance rates in soils incubated in the laboratory
under aerobic conditions.
Soil-water
ki Concentration pH OM Clay Temp Content Reference
(day-1) (pg'/g) (%) {%) (°C) (%)
3.1x10"^
4
6.8
2.7
48
19.5
23
Meikle, et
3.7x10-3
4
7.5
0.3
16
19.5
6
Ibid
5.4x10-3
4
7.2
4.1
7
19.5
30
Ibid
6.7x10-3
4
7.8
3.1
25
19.5
25
Ibid
5.6x10-4
4
6.3
1.2
42
19.5
16
Ibid
5.2x10-3
4
6.2
3.2
28
19.5
30
Ibid
3.8x10-4
4
5.9
0.3
16
19.5
12
Ibid
2.6x10-3
4
5.7
1.5
6
19.5
17
Ibid
5.2x10-3
4
6.2
3.2
28
19.5
58
Ibid
3.6x10-3
4
6.2
3.2
28
19.5
45
Ibid
3.3x10-3
4
6.2
3.2
28
19.5
32
Ibid
2.6x10-3
4
6.2
3.2
28
19.5
11
Ibid
1.9x10*3
4
6.2
3.2
28
19.5
5
Ibid
4.8x10-3
4
6.2
3.2
28
34
30
Ibid
2.8x10-3
4
6.2
3.2
28
19.5
30
Ibid
1.8x10-3
4
6.2
3.2
28
2.5
30
Ibid
7.9x10-3
4
5.7
1.0
7
34
8
Ibid
2,6x10-3
4
5.7
1.0
7
19.5
8
Ibid
2.0x10-3
4
5.7
1.0
7
2.5
8
Ibid
(Continued)
-------
TdbTe 625. (Continued).
ki
(day-1)
Concentration
(ug/g)
PH
OM
U)
ciif
temp
(°C)
Soil-water
Content
(%)
Reference
8,2*10*3
0.25
..
4
100% FC
Merkle, et al., 1976
8.2x10-3
0.25
..
4
101 FC
Ibid
6,4x10-3
0.25
--
--
--
20
100% FC
Ibid
6.4x10-3
0.25
--
--
„
20
10% FC
Ibid
2.4xlOr?
0.25
--
--
--
38
100% FC
Ibid
1.3x10-2
0.25
—
--
38
101 FC
Ibid
1.0x10-2
0.2S
* «
—
--
4
tOOX FC
Ibid
1 >0*10*2
0.25
—
--
20
100% FC
Ibid
5.0x10-3
0.25
--
--
20
10* FC
Ibid
1.0x10-2
0.25
* —
—
—
38
100% FC
Ibid
6.4X10-3
0.25
—
--
38
10% FC
Ibid
9.6x10-3
1.0
--
--
—
4
100% FC
Ibid
1 .?jtl0"2
1.0
--
--
4
10% FC
Ibid
8.6x10*3
1.0
--
--
—
20
100% FC
Ibid
8.9x10-3
1.0
--
20
10% FC
Ibid
9.1x10-3
1.0
«
38
100% FC
Ibid
9.1x10-3
1.0
--
__
--
38
10% FC
Ibid
1.4x10-2
1.0
--
--
--
4
100% FC
Ibid
8.6x10-3
1.0
--
—
—
4
10% FC
Ibid
1.1x10-2
1.0
--
—
—
20
100% FC
Ibid
9.4x10-3
1.0
--
2Q
10% FC
Ibid
1»0x10-2
1.0
--
--
--
38
100% FC
Ibid
9.9x10-3
1.0
—
—
38
10* FC
Ibid
5.5x10-3
1
6*6
2.0
30
Yoshlda and Castro, 1975
3.0x10-3
1
4.7
3.2
--
30
--
Ibid
-------
14
Table B26. Mineralization rates for carboxy- C-labeled picloram in soils under aerobic conditions.
Soil-water
kl
Concentration
pH
OM
Clay
Temp
Content
Reference
(day-1)
(iig/g)
(*)
(%)
(°C)
(%)
5.0x10-6
10
7.9
0.90
24.5
5
100?
FC
Guenzi and Beard, 1976
2.5x10-5
10
7.9
0.90
24.5
15
100%
FC
Ibid
5.0x10-5
10
7.9
0.90
24.5
25
100%
FC
Ibid
2.9x10-4
10
7.9
0.90
24.5
30
100%
FC
Ibid
1.lxl0"4
10
7.9
0.90
24.5
50
100%
FC
Ibid
2.0x10-5
10
7.9
0.83
39.0
5
100%
FC
Ibid
1.0x10-4
10
7.9
0.83
39.0
15
100%
FC
Ibid
3.7x10-4
10
7.9
0.83
39.0
25
100%
FC
Ibid
1.0x10-3
10
7.9
0.83
39.0
30
100%
FC
Ibid
5.2x10-4
10
7.9
0.83
39.0
50
100%
FC
Ibid
2.5xl0-5
10
5.5
4.20
27.0
5
100%
FC
Ibid
1.5x10-4
10
5.5
4.20
27.0
15
100%
FC
Ibid
5.5x10-4
10
5.5
4.20
27.0
25
100%
FC
Ibid
1.2x10"3
10
5.5
4.20
27.0
30
100%
FC
Ibid
1.7x10-4
10
5.5
4.20
27.0
50
100%
FC
Ibid
"0
10
6.8
3.41
83.0
5
100%
FC
Ibid
1.0x10-5
10
6.8
3.41
83.0
15
100%
FC
Ibid
4.0x10-5
10
6.8
3.41
83.0
25
100%
FC
Ibid
2.1x10-4
10
6.8
3.41
83.0
30
100%
FC
Ibid
3.1x10-4
10
6.8
3.41
83.0
50
100%
FC
Ibid
1.5x10-5
10
1.37
8.0
5
100%
FC
Ibid
1.1x10-4
10
1.37
8.0
15
100%
FC
Ibid
1.8x10-4
10
1.37
8.0
25
100%
FC
Ibid
1.2x10-3
10
1.37
8.0
30
100%
FC
Ibid
1.7x10-3
10
1.37
8.0
50
100%
FC
Ibid
(Continued)
-------
Table B26. (Continued).
ki
(day-1)
Soil-water
Concentration
(pg/9)
pH
OM
(%)
c»)
Temp
(°e)
Content
(%)
Reference
4
7.0
1.1
9
27
7.6
Melkle* et al., 1966
4
7.0
1.1
9
27
7.6
Ibid
3.20
6.8
2.7
48
19.5
23
Melkle, et al., 1973
1.60
6.8
2.7
48
19.5
23
Ibid
0.80
6.8
2.7
48
19.5
23
Ibid
0.40
6.8
2.7
48
19.5
23
I bi d
0.20
6.8
2.7
48
19-5
23
Ibid
0.10
6.8
2.7
48
19.5
23
Ibid
0.05
6.8
2.7
48
19.5
23
Ibid
4
6.2
3.2
28
19.5
58
Ibid
4
6.2
32
28
19.5
45
Ibid
4
6.2
3.2
2d
19.5
32
Ibid
4
6.2
3.2
28
19.5
11
Ibid
4
6.2
3.2
28
19.5
5
Ibid
6.2
3.2
28
34
30
Ibid
4
6.2
3.2
28
19.5
30
Ibid
4
6,2
3.2
28
2.5
30
Ibid
4
5.7
1.5
6
34
8
Ibid
4
5.7
1,5
6
19.5
8
Ibid
5.7
1.5
6
2.5
8
I bid
2.2x10
2.8x10
7.8x10
1.3x10
1.5X10
1.9X10
2.2x10
2.5x10
2.6*10'
3.7x10'
6.1x10"
5.8x10
4.1*10
2,0x10
1.3*10
8.7x10
1.1*10
4.0x10
9.0x10"
1.1x10'
*4
-3
i
r3
-4
-------
Table B27. Solvent extractable picloram disappearance rates in the field.
k-| Concentration
(day1) (kg/ha)
PH
OH
U)
Clay
(%)
Soil-water
Temp Content
(°C) (%)
Depth
(cm)
Reference
1.8x10"?
1.12
„
..
— — _
0-15
Bovey, et al.,
1969
1.3x10",
3.36
--
--
--
--
0-15
Ibid
3.4x10",
10.08
--
--
—
0-15
Ibid
>4.3x10",
1.12
—
--
--
--
0-15
Ibid
>5.7x10,
3.36
--
--
--
—
0-15
Ibid
5.1x10
10.08
—
—
—
0-15
Ibid
3.4x10"?
2.24
6.4
1.72
22(mean)
0-15
Lutz, et al.,
1973
3.6x10
4.48
6.4
1.72
22(mean)
0-15
Ibid
8.3xl0"3
_ _
—
—
0-15
Sirons, et al.
, 1977
-------
Table B28. Solvent extraetable dalapon disappearance rates 1n soils under laboratory aerobic
Incubation.
(day-V)
Concentration
(ug/g)
Soil-water
Content
(%)
Reference
4.2xl0"2
50
looi FC
Namdeo, 1972
5.1xlO'2
10
100% FC
Ibid
-------
Table B29. Solvent extractable TCA disappearance rates in soils incubated in the laboratory undei*
aerobic conditions.
Soi1-water
lq Concentration pH OM Clay Temp Content Reference
(day-1) (pg/g) {%) (%) (°C) (%)
9.6xl0~2
20
6.2x10"?
1.2x10"'
10
7.5
3.2
10
5.2
11.7
8.9x10";
10
5.2
11.7
2.3x10";
10
7.7
4.2
4.8x10
10
7.7
4.2
25
100% FC
McGrath, 1976
6
25
10
Smith, 1974
30
25
35
Ibid
30
25
20
Ibid
69
25
40
Ibid
69
25
20
Ibid
-------
Table B30. Solvent extractable TCA disappearance rates In the field.
k1
(
-------
Table B31. Solvent extractable glyphosate disappearance rates in soil under greenhouse conditions.
Soil-water
ki Concentration pH OM Clay Temp Content Reference
(day-1) (yg/g) (%) (X) (°C) (%)
2.6x10
4
7.0
6.0
36.8
26-32 1
Rueppel, et
2.8xlO"Z
8
7.0
6.0
36.8
26-32 1
Ibid
5.3xlO"3
5.7
1.0
2.3
26-32 1
I b1 d
2.3xl0_1
4
6.5
1.0
0.6
26-32 1
Ibid
2.3xl0-1
8
6.5
1.0
0.6
26-32 1
Ibid
-------
Table B32. Mineralization rates for glyphosate 1n soils Incubated In the laboratory under aerobic
Incubation.
{day-!}
Concentration
(yg/g)
pH
OH
<%)
Temp
(°C)
Reference
1.6x10"?
6.6
3.8
25
MosMer and Penner, 1978
3.3x10 ,
6.6
3.7
25
Ibid
1.1x10
4.4
1.2
25
Ibid
1.8x10"a
375
6.9
2.10
Normura and Hilton, 1977
1.4x10",
366
7.0
3.07
Ibid
7. 3xl'0r «
365
6il
4.88
Ibid
2.0x10"I
376
5.7
9.48
Ibid
1.3x10"
373
5.5
9.71
Ibid
2.3x10"?
2.7
2.7
5.7
Sprankle, et al., 1975
6.2x10",
2.7
—
--
Ibid
5.0x10
2.7
3.6
3.8
Ibid
-------
Table B33. Solvent extractable parathion disappearance rate in soils under laboratory aerobic
incubation.
kl
(day-1)
Concentration
(pg/g)
PH
0M
{%)
Clay
(5!)
Temp
(°C)
Reference
1.4x10"!:
1
7.2
1.3
0
27
Katan, et al., 1976
5.0x10
1
6.0
4.7
24
27
Ibid
3.3xlO"2
200
—
—
--
30
Lichtenstein and Schulz, 1964
3.3X10"2
6
—
--
—
26
Sacher, et al., 1971
ro
O)
a>
-------
Table B34. Solvent extractable parathlon disappearance rates In the flooded soils Incubated 1n the
laboratory.
ki
(day-1)
Concentration
(ug/g)
pH
OH
(*>
Temp
(~C)
Reference
;?.0XlO~^
30
6.0
1.35
30
Rajar1um,and Sethunathan, 1975
7.9x10"?
6.1x10";
6.1x10";
3.2x10";
3.6x10"
50
50
50
50
50
3.15
3.15
3.50
5.25
5.50
2.20
5.90
3.20
0.95
0.80
30
30
30
&)
30
Sethunathan, 1973a
Ibid
Ibid
Ibid
Ibid
3.7*10"*
50
—
—
30
Sethunathan, 1973c
4.3x10*]
1.1x10";
7.7x10";
5.6x10
150
150
150
150
6.6
417
7.6
4.8
2.0
3.2
1.5
4.4
30
30
¦30
30
Sethunathan and Yoshlda, 1973
Ibid
Ibid
Ibid
-------
Table B35. Solvent extractable parathion disappearance rates in the field.
ki Concentration Temp Depth
(day~^) (kg/ha) (°C) (cm) Reference
2.8x10"^ 5.6 30 0-12 Lichtenstein and Schulz, 1964
3.0x10"? 1.1 Sacher, et al., 1971
3.0x10", 1.1 Ibid
3.2x10", 1.1 Ibid
5.7x10", 1.1 Ibid
3.8x10", 1.1 Ibid
2.8x10 1.1 Ibid
2.3x10"] 2.24 Spencer, et al., 1975
1.0x10"' 4.48 Ibid
5.2x10", 8.96 Ibid
2.4x10", -- Ibid
3.5x10 -- Ibid
-------
Table B36. Solvent extractable methylparathIon disappearance rates In soils Incubated 1n the lab-
oratory under aerobic conditions.
ki
(day"1)
Concentration pH
(pg/g)
OM
<*)
Temp
(°c)
Soil-water
Content
(*)
Reference
9.5xl0~2
10 6.0
4.2
2.3
27
20
Llchtensteln, et al., 1977
2.3X1Q"1
200
—
--
30
—
Llchtensetln and Schulz, 1964
-------
Table B37. Solvent extractable diazinon disappearance rates in soils incubated in the laboratory
under aerobic conditions.
Soil-water
ki Concentration pH OM Clay Temp Content Reference
(day-1) (yg/g) (X) (%) (°C) (%)
1.8x10"?
0.45
6.0
2.0
2.6
30
75* WHC
Bro-Rasmussen, et
1.3x10,
0.45
6.0
2.0
2.6
30
25% WHC
Ibid
1.2x10",
4.5
6.0
2.0
2.6
30
75% WHC
Ibid
1.2x10",
4.5
6.0
2.0
2.6
30
25% WHC
Ibid
3.2x10",
0.45
6.3
2.7
8.6
30
75% WHC
Ibid
1.6x10",
0.45
6.3
2.7
8.6
30
25% WHC
Ibid
2.6x10",
4.5
6.3
2.7
8.6
30
75% WHC
Ibid
1.4x10
4.5
6.3
2.7
8.6
30
25% WHC
Ibid
l.OxlO"1
16.7
6.7
3.1
21
25
21
Getzin, 1967
5.6x10~«
16.7
6.7
3.1
21
15
20
Getzin, 1968
1.2x10",
16.7
6.7
3.1
21
25
20
Ibid
2.2x10
16.7
6.7
3.1
21
35
20
Ibid
-------
Table B38. Solvent extractable dlazlnon disappearance rates in flooded soils Incubated 1n the
laboratory.
Hi
(day"!)
Concentration
(pg/g)
PH
OM
(?)
°i8
Temp
(°C)
Reference
7.2x10"*
4.9
6.2
5.4
--
25
Laanio, et al., 1972
7.9x10"?
4.0x10 i
2.0x10"
50
50
50
6.6
7.6
4.7
2.0
1.5
3.2
30
30
30
Sethunathan and HacRae, 1969
Ibid
Ibid
9.1xl0"2
40
6.6
2.0
—
--
Sethunathan and Yoshida, 1969
-------
Table B39. Solvent extractable fonofos disappearance rates in the field (complex first-order).
(day-1)
tl
ki
(day-l)
Concentration
(kg/ha)
PH
Temp
(°C)
Depth
(cm)
Reference
3.6xl0"2
5.3xlO~3
5.35
5.7
19
0-15
Kiigemgi and Terriere, 1971
2.4xlO~2
9.5X10"3
11.2
—
—
0-15
Schulz and Lichtenstein, 1971
-------
table B40. Solvent extractable fonofos disappearance rates 1n the field (simple first-order).
ki Concentration OM Clay Depth
(day-1) (kg/ha) pH (%) ''(X). (cm) Reference
7.4xl0"3 2.24 5.7 43.4 -- 0-10 Mathur, et al., 1976
2.7xlO"2 10 8.5 0.54 16.3 0-15 Talekar, et al., T977
-------
Table B41. Solvent extractable malathion disappearance rates in soils incubated in the laboratory under
aerobic conditions.
kl
(day-1)
Concentration
(ng/g)
PH
OH
(%)
Clay
(%)
Temp
m
Soil-water
Content
(X)
Reference
9.2xl0_1
20
5.4
6.8
20
25
65% UHC
Gibson and Burns, 1977
2.48
5
6.4
_ _
_ _
Konrad, et al., 1969
3.11
5
7.2
48.7
--
Ibid
1.66
5
3.8
—
' .
—
Ibid
<0.69
16
7.2
2.75
25-26.
28.3
Walker and Stojanovic, 1973
0.33
16
5.3
0.62
25-26
13.1
Ibid
<0.69
16
7.4
1.82
- ¦"
25-26
28
Ibid
-------
Table B42. Solvent extractable phorate disappearance rates In sails Incubated in the laboratory under
aerobic conditions.
kl ,
(day-1)
Concentration
(pg/g)
PH
OM
<*)
cli5
Temp
(°C)
Soil-water
Content
(*>
Reference
7.6x10"?
9.0xl0"f
1.0x10"
4
4
4
—
—
—
24
24
24
Getzln and Chapman, I960
Ibid
Ibid
8.4x10"3
17
6.3
3.1
21
25
Getzln and Shank, 1970
-------
Table B44. Solvent extractable carbofuran disappearance rates in soils incubated in the laboratory
under aerobic conditions.
Soil-water
ki Concentration pH OM Clay Temp Content Reference
(day-1) (Mg/g) (%) {%) (°C) (£)
9.5xl0"2 8.3 7.8 1.0 19 25 1.05 FC Getzin, 1973
l.lxlO"1 13.9 7.8 1.0 19 25 1.05 FC Ibid
5.3xl0"2 10.0 6.2 7.2 36 25 1.05 FC Ibid
4.3xl0~2 16.7 6.2 7.2 36 25 1.05 FC Ibid
1.4xl0-2 8.3 6.0 3.0 17 25 1.05 FC Ibid
9.4xl0~3 16.7 5.9 40.0 - 25 1.05 FC Ibid
7J5xlO"3 50 6.2 1.61 -- -- 0.5 FC Venkateswarlu, et al.,
1977
-------
Table B43. Solvent extractable phorate disappearance rates in the field.
Iq
(day-1)
Concentration
(kg/ha)
Depth
(cm)
Reference
7-. 9x10" ~
2.24
0-10
Menzer, et al., 1970
1.4x10",
2.24
0-10
Ibid
9.2x10",
2.24
0-10
Ibid
8.0x10
4.48
0-10
Ibid
8.1x10"?
2
0-15
Suett, 1975
9.5x10
2
0-15
Ibid
-------
Table B45. Solvent extractable carbofuran disappearance rates in flooded soils.
ki
(day*1)
Concentration pH
(vg/g)
OM
(%)
SoiKwater
Content
(X)
Reference
4.0x10
2.9x10
2.6x10
-2
-2
-2
6.5x10"
50
50
50
50
6.2
5.0
4.2
3.0
1.61
3.25
B.21
26.41
125 Venkateswarlu, et al., 1977
125 Ibid
125 Ibid
125 Ibid
-------
Table B46. Solvent extractable carbofuran disappearance rates In the f-1eld.
(dSr1)
Concentration
(kg/ha)
pH
OM
(%)
Temp
(°C)
Depth
(ion)
Reference
1.50xl0'2
5.41
5.20 & 6.35
—
--
--
0-10
Caro, et al., 1973
5.9xl0~3
5.41
5.20 & 6.35
—
—
--
0-10
Ibid
7.4xl0~3
4.16
5.20 & 6.35
—
—
—
0-15
Ibid
4.1xl0~2
4.48
5.7
43.4
--
--
0-10
Hathur, et al., 1976
2.2xlO"2
4.48
5.7
43.4
—
0-10
Ibid
6.9xl0"2
10
8.5
0.54
16.3
-28
0-15
Talekarj et al., 1977
-------
14
Table B47. Mineralization rates of C-labeled carbofuran in soils under aerobic conditions.
kl
(day-1)
Concentration
(vg/g)
PH
0M Clay
(%) {%)
Temp
(°c)
Soil-water
Content
(%)
Reference
Ring Labeled
1.6x10
13.9
7.8
1.0 19
25
105% FC
Getzin, 1973
1.1x10"
16.7
6.2
7.2 36
25
105% FC
Ibid
O
Carbonyl Labeled
5.6x10",
8.3
7.8
1.0 19
25
105% FC
Getzin, 1973
5.9x10",
10.0
6.2
7.2 36
25
105% FC
Ibid
1.2x10",
8.3
6.0
3.0 17
25
105% FC
Ibid
6.1x10"
16.7
5.9
40.0
25
105% FC
Ibid
-------
Table B48. Solvent extractable carbaryl disappearance rates In soils Incubated in the laboratory
under aerobic conditions.
ki
(day-1)
Concentration
(wg/g)
PH
0M
(*>
Clay
(%)
Tiemp
(6C)
Soil-water
Content
(*)
Reference
Ring labeled
80% FC
2.6x10-
2
5.4
5.8
40
25
Kazano, et al., 1972
3.4xi0"2
2
6.1
12.8
21
25
801 FC
Ibid
7.3xl0~2
2
6.3
1.5
19
25
80} FC
Ibid
2.1xlO~2
2
5.6
4.1
28
25
80* FC
Ibid
3.3xlO~2
2
5.5
3.3
11
25
60% FC
Ibid
-------
Table B49. Solvent extractable carbaryl disappearance rates in the field.
k] Concentration OM Clay Depth
(day-1) (kg/ha) pH {%) {%) (cm) Reference
2.8xl0"2 5.03 5.20 1.7 16 0-30 Caro, et al., 1974
8.7x10"^ 3.436-30.24 -- -- -- 0-15 Johnson and Stansbury, 1975
>1.9xl0-1 3.36 — — — 0-5 Kuhr, et al., 1974
ro
cn
ro
-------
Table B50. Solvent extractable DOT disappearance rates 1n the field*.'
ki Concentration OM Clay Depth
(day~J) (kg/ha) pH (1) .(%) (cm) Reference
3.1x10"
11.2
__ ..
0-15
Lichtensteln, et al., 1971
2.6x10"
112.0
0-15
Ibid
l.lxio":
112
6.9
1.8
0-15
Lichtensteln, et al., 1960
1.6x10"
112
6.8
0.8
0-15
Ibid
8.1x10"
112
4.9
74.5
0-15
I bid
6.9X10"
112
6.0
2.0
0-15
Ibid
4.7x10"
112
7.2
a.8
0-15
Ibid
4,2x10"
112
7.1
3.6
- 0-15
Ibid
7.7x10"
112
6.8
40.0
0-15
Ibid
1.2x10"
(first 1/2 yr)
11.2
40.0
0-15
Lichtensteln and Schulz, 1959b
8.4x10"
(3 years)
11.2
40.0
0-15
Ibid
3.0x10"
(first 1/2 yr)
11.2
' .
3.8
0-15
Ibid
9.4x10"
(3 years)
11.2
«
3.8
0-15
Ibid
4.4x10"
28
4.7
0-15
Nash and Wool son, 1967
2.7x10'
112
4.7
--
0-15
Ibid
1.5x10"
448
4.7
—
0-15
Ibid
2.7x10"
112
--
¦ --
0-15
Ibid
1.2x10"
448
--
—
0-15
Ibid
1.7x10"
112
5.2
0-15
Ibid
1.2x10"
448
5.2
6-15
Ibid
4.0x10"
587
0-30
Stewart and Chlsholm, 1971
9.2x10"
—
--
—
—
Suzuki, et al., 1977
(Continued)
-------
Table B50. (Continued)
ki
(dayl)
Concentration
(kg/ha)
pH
OM
(%)
Clay
(*>
Depth
(cm)
Reference
1.OxlO~o(aerobic)
56
8.4
1.9
0-15
Guenzi, et al., 1971
3.9x10" (flooded)
56
8.4
1.9
0-15
Ibid
2.6x10"3
5
8.5
0.54
16.3
0-15
Talekar, et al., 1977
6.5x10",
2.24
0-1.27
Ware, et al., 1977
5.1x10",
2.24
0-1.27
Ibid
4.2x10",
2.24
0-1.27
Ibid
3.9x10
2.24
0-1.25
Ibid
7.lxlO"5
3.0
0-60
Voerman and Besemer, 1975
-------
Table B51. Solvent extractabte DDT disappearance rates In flooded or anaerobic soils Incubated in the
laboratory.
kl
Way-!)
Concentration
(pg/g)
PH
OM
(%)
£!l!
temp
(pc)
Rei
1.6x10"?
10-20
5.9
4.64
34
28
Burge,
1971
8.7x10"
10-20
5.9
4.64
34
28
Ibid
7.1xl0"|
200
6.2
4.64
34.3
35
Glass*
1972
3.4x10";:
200
7.5
2.68
52.6
35
Ibid
3.6x10";
200
5.0
1.72
15.6
35
Ibid
3.6x10
200
5.4
0.1
13.8
35
Ibid
4.5x10"?
10
6.4
3.1
29.8
30
Guenzi
and 1
7.3x10",
10
6.4
3.1
29.8
40
Ibid
5.8x10*5
10
6.4
3.1
29.8
SO
Ibid
1;5xl0
10
6.4
3.1
29.8
60
Ibid
Reference
-------
Table B52. Solvent extractable aldrirt and dieldrin disappearance rates in the field.
ki Concentration OM Clay Depth
(day-1) (kg/ha) pH (%) (%) (cm) Reference
4.9x10"^ 44.8 7.8 1.04 49.3 0-15 Cliath and Spencer, 1971
2.1x10 44.8 7.8 0.48 17.5 0-15 Ibid
1.3x10":* 56 8.4 1.9 0-15 Guenzi, et al.. 1971
1.5x10 56 8.4 1.9 0-15 Ibid
3.0x10"? 22.4 0-15 Lichtenstein and Schulz, 1959a
2.3x10"^ 224 0-15 Ibid
4.1x10", 22.4 0-15 Ibid
2.0x10 224 0-15 Ibid
6.2x10"? 22.4 — 40.0 0-15 Lichtenstein and Schulz, 1959a
1.8x10", 22.4 -- 40.0 — 0-15 Ibid
9.6x10 , 22.4 — 3.8 — 0-15 Ibid
2.4x10 22.4 — 3.8 — 0-15 Ibid
9.8xl0"1 28 0-12.7 Lichtenstein, et al., 1970
7.9x10 28 0-12.7 Ibid
7.0x10"^ 0-60 Voerman and Besemer, 1975
1.9x10"? 5.6 0-15 Wilkinson and Finlayson, 1964
1.8x10" 5.6 0-15 Ibid
1.3xl0"J 22.4 6.2 0.83 0-15 Willis, et al., 1972
4.8x10", 22.4 6.2 0.83 0-15 Ibid
1.3x10 22.4 6.2 0.83 0-15 Ibid
-------
Table B53. Solvent extractable aldrln and dieldrin disappearance rates in solTs incubated in the
laboratory under aerobic conditions.
k-i
(day-1)
Concentration
(pg/g)
PH
0M
(*)
Clay
(X)
Temp
m
Reference
1.8x10"3
10
6.0
4.2
23
27
Llchtensteln. et al., 1977
3.3xl0~«
20
3.8
7
Ltchtensteln and Schulz, 1959b
l.oxio";
20
3.8
26
Ibid
3.8x10
20
"" ~
3.8
- 4
46
Ibid
-------
Table B54. Solvent extractable endrin disappearance rates in the field.
ki Concentration OM Clay
(day-1) (kg/ha) pH {%) {%) Reference
1.5x10-^ 56 8.4 1.9 Guenzi, et al., 1971
5.3x10"3 56 8.4 1.9 Ibid
ro
tn
00
-------
Table B55. Solvent extractable endrln disappearance rate In flooded soils under laboratory incubation
conditions.
ki
(day-1)
Concentration
(pg/g)
PH
GM
(V
Reference
4.0x10"?
25
6.2
1.61
Gowa and Sethunathan,
5.2x10',
25
4.8
2.38
Ibid
5.5x10';
25
5.0
3.25
Ibid
2.0x10';
25
5.0
1.24
Ibid
1.9x10
25
5.9
1.89
Ibid
5.0x10,
25
4.2
9;2V
Ibid
2.1x10"-
25
3.0
27.81
Ibid
8.8x10" ¦
25
6.0
0.02
Ibid
1.8x10"?
25
6.2
1.61
Gowa and Sethunathan,
1.7x10';
25
5.0
3.25
Ibid
2.9x10
25
4.2
8.21
Ibid
-------
Table B56. Solvent extractable chlordane disappearance rates in the field.
kl .
(day-1)
Concentration
(kg/ha)
PH
0M
(%)
Clay
(%)
Depth
(cm)
Reference
8.0xl0r
3.4
Harris and Suns, 1975
6.9x10 ,
3.4
Ibid
2.7x10";:
3.4
Ibid
6.6x10",
3.4
Ibid
7.9x10 "?
3.4
Ibid
9.0x10"?
3.4
Ibid
2.8x10"?
3.4
Ibid
2.7x10
3.4
Ibid
<4.6xl0~4
336
--
—
--
0-60
Stewart and Chisholm, 1971
3.7x10"^
3
7.9
1.7
28.6
0-30
Tafuri, et al., 1977
3.0x10",
6
7.9
1.7
28.6
0-30
Ibid
2.2x10
3
7.9
1.7
28.6
0-30
Ibid
2.5x10"?
5.6
6.9
1.5
4
0-23
Wilson and Oloffs, 1973
1.8x10",
5.6
6.9
1.5
4
0-23
Ibid
1.4x10" "I
11.2
4.3
9.8
35
0-23
Ibid
7.9x10
11.2
4.3
9.8
35
0-23
Ibid
-------
Table B57. Solvent extractable heptachlor disappearance rates In the field.
k-|
(day-1)
Concentration
(kg/ha)
PH
OM
(*)
Depth
(cm)
Reference
5,4x1O'o
56
8.4
1.9
0-15
Guenzl, et al., 1971
1.4x10
56
8.4
1.9
Ibid
l.lxlO'J
5.6
0-12.7
L1chtenste1n, et al., 1970
7.8x10"
5.6
Ibid
1.7x10"3
5.6
0-15
Wilkinson and Flnlayson, 1964
-------
Table B58. Sol vent.extractable heptachlor disappearance rates in soils under laboratory aerobic
incubation.
Iq Concentration OM Temp
(day-1) (yg/g) {%) (°C) Reference
5.6x10"^ 20 3.8 7 Lichtenstein and Schulz, 1959b
1.2xl0~2 20 3.8 26 Ibid
7.2xl0"2 20 3.8 46 Ibid
-------
Table B59. Solvent extractable lindane disappearance rates 1n the field.
ki Concentration CM Clay Depth
(day-1) (kg/ha) pH {%) (%) (cm) Reference
2.3x10"? 44.8 7.8 1.04 49.3 0-15 Cllath and Spencer, 1971
2.9x10" 44.8 7.8 0.48 17.5 0-15 Ibid
4.1x10"! 56 8.4 1.9 — 0-15 Guenzl, et al., 1971
7;9xlO'J 56 8.4 1.9 0-15 Ibid
2.0x10" i? 11.2 0-15 Lichtensteln and Schulz, 1959a
1.4x10', 112 0-15 Ibid
1.7x10"; 11.2 0-16 Ibid
1.3x10" 112 0-15 Ibid
1.5x10"? 11.2 - 40 CM5 Lichtensteln and Schulz, 1959b
8.2x10", 11.2 - 40 0-15 Ibid
4.9x10"; 11.2 -- 3.8 0-15 Ibid
2,0x10" 11.2 -- 3.8 0-15 I bid
1.1x10"2 11.2 0-15 Lichtensteln, et al., 1971
1.2x10" 112.0 0-15 Ibid
6.0x10"^ 3.Q 0-60 Voerman and Besemer, 1975
-------
Table B60. Solvent extractable lindane disappearance rates 1n soils Incubated 1n the laboratory under
aerobic conditions.
kl
(day-1)
Concentration
(ug/g)
pH
OM
(%)
Soil-water
Content
(*>
Reference
3.1x10"3
32.7
5.8
5.2
67% FC
Mathur and Saha, 1977
2.1xlO"3
32.7
5.8
5.2
67% FC
Ibid
ro
CT\
-------
Table B61. Solvent extractable lindane disappearance rates 1n flooded soils in laboratory studies.
kl
(day-1)
Concentration
Ug/g)
PH
OM
(*)
Temp
(°C)
Soll^-water
Content
(%)
Reference
6.4x10"3
3.27
5.8
5.2
23
>100
Mathur and Saha, 1977
2.9xl0~3
3.27
5.8
5.2
23
>100
Ibid
-------
Table 862. Solvent extractable PCP disappearance rates in flooded soils.
Soil-water
ki Concentration pH OM Clay Content Reference
(day-1) (ug/g) (%) {%) (%)
8.0x10"« 100
6.6x10", 100
6.0x10", 100
3.9x10", 100
4.2x10", 100
2.3x10", 100
1.1x10" 100
5.9x10", 80
S? 7.9xl0"f 80
01 1.0x10"' 80
1.1x10", 80
8.9xl0"f 40
1.2x10"' 40
7.9x10", 40
9.3x10" 40
5.8
7.9
5.4
250
6.0
7.5
4.5
250
4.6
1.8
20.5
250
5.2
1.5
21.0
250
5.9
3.6
22.7
250
5.8
1.9
23.1
250
6.1
1.2
22.4
250
66
66
66
66
82
82
82
82
Kauwatsuka and Igarashi, 1975
Ibid
Ibid
Ibid
Ibid
Ibid
Ibid
Watanabe, 1978
Ibid
Ibid
Ibid
Ibid
Ibid
Ibid
Ibid
-------
Table B63. Solvent extractable PCP disappearance rates 1n soils Incubated 1n the laboratory under
aerobic conditions.
Soi1-water
ki Concentration pH OM Clay Content Reference
(day-1) (vg/9> (%) (%1 (%)
1.6xl0-2 100 5.8 7.9 5.4 60% WHC Kauwatsuka and Igarashl, 1975
2.7xl0*"? 100 6.0 7.5 4.5 60% WHC Ibid
7.3xlO"3 100 4.6 1.8 20;6 60% WHC Ibid
2.0*10"2 100 5.2 1.5 21.0 602 WHC Ibid
3.9xl0"2 100 4.9 1.8 22.8 601 WHC Ibid
KlklO"2 100 6.4 1.2 27.5 60$ WHC I bid
-------
APPENDIX C
268
-------
Table CI. Correlation coefficients between sorption maxima and selected
soil properties by Ballaux and PeasVee (1975).
Sorption maximat
Soil property
S1
max
S2
max
Clay content
0.73
0.76
Free-fe oxide
0.83*
0.22
Surface area (ethylene
glycol)
0.69
0.70
Organic, matter
0.27
0.87*
Ca-P
0.99**
0.S2
tsLx and SjLj were estimated from isotherms 1n which Initial P concentra
tions were™.06 to 0.3 and 3.1 to.4.7 ymol/ml, respectively
269
-------
Table C2. Correlation coefficients between phosphate sorption parameters
and soil properties from Vijayachandran and Harter (1975).
Property % P sorption
Fe - dithionate 0.19
- HCl-NaOH 0.21
A1 - dithionate 0.46*
- HCl-NaOH 0.45*
Organic carbon 0.75**
* denotes significance at the 5% level
** denotes significance at the 1% level
270
-------
Table C3. Phosphate sorption correlated with extractable A1 and Fe by Williams et al. (7958).
Acetate
Soil group Tamm oxalate method Dithionite method soluble
Fe2°3
ai2p3
R2°3 Fe2°3
ai2o3
R2°3
ai2o3
Sorption at pH 4t
Basic igneous
0.671*
0.964***
0.918*** -0.378
0.808**
-0.219
0.817**
Slate
0.640*
0.913***
0.909*** 0.289
0.713*
0.508
0.843**
O.R.S,
0.744*
0.994***
0.988*** 0.497
0.978***
0.846**
0.958***
Granitic
0.655*
0.774**
0.874*** 0.480
0.886***
0.679*
0.462
Over-all
0.646***
--
0.928*** -0.020
0.862***
--
0.881***
Sorption at pH 2
,6tt
Basic Igneous
0.724*
0.945***
0.921*** -0.345
0.821**
-0.185
0.912***
Slate
0.664*
0.909*^*
0.919*** 0.440
0/825**
0.670*
0.885***
O.R.S.
0.665*
0.979***
0.958*** 0.335
0.959***
0.734*
0.969***
Granitic
0.491
0.666*
0.715* 0.305
0.752*
0.492
0.236
Over-all
0.609***
--
0.870*** 0.026
0.881***
0.304
—
* denotes significance at the 5% level
** denotes significance at the 1% level
*** denotes significance at the 0.1X level
t By the method Piper (1942) In which the soil was saturated with phosphate by prolonged treatment
with pH 4 (NHa^POj. After removing the excess with alcohol, the adsorbed phosphate was removed
with 0.125 N NaOH.
tt Sorption of phosphate from pH 2.6 acetic acid solution containing KH^P04 (67 mg P/1G0 g soil).
-------
Table C4. Regression equations resulting from correlations of phosphate sorption and Taram extraotable
F6 or Al (Williams et al., 1968).
Property
Soil
Group
Regression equation
pH 4
PH 2.6
Tamm Al
Basic groups
S = 0.67x + 5.28
S
0.021X + 0.360
Slate
S = 0.91x + 3.03
S =
0.039x + 0.247
O.R.S. + granitic
S = 0,-91x +.1.19
S =
0.039x + 0.151
Tamm Fe
All
S = 1.23x + 2.51
S =
0.047x + 0.230
Tamm Fe + Al
Basic igneous
S = 0.47x + 3.78
S =
0.015x + 0.305
O.R.S. + slate + granitic
S = 0.70x - 0.66
S =
0.030x + 0.081
S •= mmoles P2O5/IOO .9 soil
x= mmoles Tamm M2O3/IOO g soil
-------
Table C5. Correlation coefficients of phosphate sorption parameters
versus physical and chemical properties of the soils, their
clay fractions, and bottom sediments used.by McCallister and
Logan (1978).
Adsorption
Adsorption
Property
maximum
energy
Soils (n=7)
Bray PI
"Available" P
n.s.
rO,Q68*
Total P
0.729
n.s.
Inorganic P
0.809*
n.s.
Fine clay
0.735
n.s.
Soil clay fractions (n*7)
CDB-Fe
nvs^
CDB-A1
n.s.
0.823*
Total P
n.s.
n.s.
Inorganic P
n.s.
n.s.
Organic P
0.741
n.s.
Fine clay
o,s.
0.679
Sediments (n=5)
Amorphous Si
0.997**
n.s.
CDB-Fe
0.972**
n.s.
CDB-A1
0.847
n.s.
Oxalate-Fe
0.981**
n.s.
Oxalate-Al
0.974**
n.s.
Bray PI
"Available" P
n.s.
n.s.
Total P
0.993**
n.s.
Inorganic P
0.960**
n.s.
CaCO-
equlvalent
-0.850
n.s.
Total clay
0.967**
n.s.
Fine clay
0.916*
n.s.
PH
-0.923*
n.s.
*Values not marked are significant at the 10% level; those marked with
a "*" are significant at the 5% level; those marked with a "**" are signif-
at the 12 level; "n.s." indicates no significant relationship between the
factors at the lOt level.
273
-------
Table C6. Correlation and regression coeficients for phosphate sorption and properties for the
tropical and British soils (Lopez-Hernand and Buruham, 1974).
P sorption index (Bache and Williams) P sorption capacity (Piper)
Regress Regress
Variable Simple coeff. Simple coeff.
Tropical soils
PH
Carbon
Free Fe
Ext. A1
Clay
British soils
PH
Carbon
Free Fe
Ext. A1
Clay
-0.210ns
0.044ns
0.328**
0.721****
0.447***
-0.01ns
-0.016ns
0.701****
0.633****
0.169ns
2.678
-0.071
0.090
34.751
0.193
5.796
2.429
0.447
8.212
-0.156
-0.217ns
0.391***
0.259*
0.729****
0.338**
0.638
1.681
0.027
10.574
0.054
**t *** ^ ****> significant at 10, 5, 1, 0.12S respectively.
-------
Table C7. Correlation coefficients and regression equations between phosphate retention and soil
properties for A and B horizons (Saunders, 1965).
Soil property
Soils
(No.)
Horizon
Correlation
Coeff. (r)
Regression equation1"
Organic
All soils
(49)
A
0.186 n.s.
carbon
Less gley
and podzols
(43)
A
0.787***
% P retn.
o
8.0 + 5.68 + 0.70 (5EC)***
% C
o
1.8 + 0.11 +0.013 (% P retn.)***
Total
All soils
(49)
A
0.533***
% P retn.
V
16.0 + 60.1 + 18.4 (t N)**
n1trogen
Less gley
(43)
% P r^th.
and podzols
A
0.759***
5.4 + 93:2 + 12.0 (X N)***
Org. P
All soils
(49)
A
0.601***
% P retn.
a.
20.9 * 470 + 90 (X org. P)***
Less gley
and podzols
(43)
A
0.552***
% P retn.
. c
25.3 + 400 + 94 (X org. P)
Clay content
All soils
(49)
A
0.327*
% P retn.
s
31.0 + 0.48 + 0.20 (* clay)*
X loss on
All soils
(48)
A
0.517***
% P rfetn.
8
26.1 + 1.06 +0.26 (X L. on I.)***
Ignition
Less gley
and podzols
(43)
A
0.914***
% P retn.
-4.0 + 3.03 + 0.21 (% L. on I.)***
*, **, ***, significance at the levels of 0.1, 1, and 5% respectively,
t Pretention measured by the method of Piper- (1942).
-------
Table C8. ¦Regression equations of phosphate retention on aluminum and iron values for soil groups
(Saunders, 1965)
Soil group Horizon Tamm Al+ Tamm Fe+. Citrate-dithionite Fe
(% P retn.) (% P retn.) (% P retn.)
"Crystalline" soils
Yellow-grey earths and A&AB ==i0.'6 + 1.82 Al** =14.7 + 1.16 Fe*** = 19.1 + 0.29 Fe**
inter-grade to yellow-
brown earths
Northern yellow-brown A&AB 13.6 + 2.92 Al** ? 21.9 + 1.33 Fe* = 21.0 + 0.86 Fe**
earths
Po'dzols A&AB = -9.6 + 4.39 Al**
Brown granular loams A&AB = 6.4 + 2.70 Al** = 11.7 * 2.08 Fe** = -6.8 + 0.78 Fe**
and clays
Recent soils from A&AB = -14.8 + 4.04 Al** = -14.8 + 4.04 Fe**
alluvium
"Crystalline" soils A&AB = 0.8 + 3.03 Al*** = 13.7 + 1.70 Fe***
(at 500 mg P/100 g soil)
"Amorphous" soils
High country and A&AB =16.4 + 1.62 Al*** *='14.3 + 2.65 Fe*** = 2.06 + 1.49 Fe**
southern and
central yellow-
brown earths
*, **, ***, significance at the levels of 0.1, 1, 5%, respectively,
t Pretention measured by the method of Piper (1942).
-------
Table C9. Correlation coefficients for soil groups between phosphate retention*
Iron values (Saunders, 1965).
and aluminum and
Soil group
Horizon
Tamm
A1
Tamm
Fe
Tamri
A1 + Fe
Neutral
citrate
dlthionlte
Fe
Brown-grey earths
A + AB
0.192
-0.718
0.507
0.336
Yeilow-grey earths
inter-grade to
yellow-brown earths
A + AB
0.734**
0.795**
0.822**
0.756**
High country, southern
and central yellow-
brown earths
A + AB
0.962***
0.947***
0.965***
0.886**
Northern yellow-
brown earths
A + AB
0.954**
0.881*
0.934*
0.989**
Prpdzols
A + AB
0.862***
0.048
0,780**
Yellow-brown loams
younger red and
brown loams (at
2,560 mg P/1Q0 g soil)
A + AB
0.315
0.113
0.333
Brown granualar loams
ahd clays
A + AB
0.972***
0.940**
0.987***
0.948**
Recent soils from
alluvium
A + AB
0.942**
0.942**
0.944**
"Crystalline" soils
(at 500 mg p/100 g soil)
A + AB
0.873***
0.62a***
0.788***
t P retention measured by the method of Piper (1942).
*, **, ***, slgnlfance at the levels of 0.1, 1. 5%, respectively.
-------
Table CIO. Langmuir constants published in literature.
Soil or
Isotherm no. Sm,„ ug P/g soil k, ml/ng P Remarks Reference
ffiaX i
ro
00
Alligator
-1
17.2
1.48
Initial P concentration: 2-10pg/ml(A)l
-2
28.8
0.32
10-15pg/ml(B)
-3
45.7
0.16
20-25pg/ml(C)
-4
46.9
0.13
40-55vig/ml (D)
Crider
-1
15.2
1.00
(A)
-2
18.2
0.47
B)
-3
24.1
0.20
(C)
-4
42.3
0.03
(D)
Grenada
-1
13.1
0.92
(A)
-2
18.4
0.31
(B)
-3
21.7
0.19
(C)
-4
22.5
0.10
(D)
Pembroke
-1
14.4
0.97
(A)
-2
17.8
0.46
(B)
-3
25.3
0.16
(C)
-4
27.7
0.08
(D)
Zanesville
i-l
12.6
1.23
(A)
-2
25.4
0.15
(B)
-3
31.3
0.13
(C)
-4
37.0
0.07
(0)
(1975)
(Continued)
-------
Table CIO (Continued)
Soil or
Isotherm no.
Sm=.u n9 p/9 so-11 k» ml/wg P Remarks
max»
Reference
Soil 1
Soil 2
Sol 1 3
Soil 1
Soil 2
Soil 3
Soil 1
Soil 2
Soil 3
121.2
112.7
0.0
113.3
290.3
181.8
166.6
347.8
219.1
0.52
0.37
0.0
0.83
0.68
0.28
1.50
1.59
0.33
Na+ saturated el ay fraction; 0-24,000 El-Nennah (1975)
ug P/ml in equilibrium solution
Mg^+ saturated clay fraction; 0-24,000
pg P/ml in equilibrium solution
Ca^+ saturated clay fraction; 0-24000
iig P/ml in equilibrium solution
Brooks
Camillerl
Wesche
Nicholson
Rlbaldone
Harris
21
56
55
166
98
155
0.16
0.02
0.06
0.03
0.02
0.02
P concentrations at equilibrium were
0-10 jig P/ml.
Correlation coefficients (r) for the 11st of
each isotherm 1n this group to the language
equation from 0.864 to 0.999. Soil properties
not given in this article.
Haysom (1974)
(Continued)
-------
Table CIO. (Continued)
Soil or
Isotherm no. Sm,„ yg P/g soil k, ml/yg P Remarks Reference
irio X)
Makennan
187
0.05
Quod
116
0.04
Webster
188
0.04
Walker
101
0.01
Davies
140
0.04
Daguara
225
0.04
Elliot
193
0.06
Brown
176
0.07
Mullar
188
0.06
McEwen
219
0.04
Galletly
402
0.09
Large
67
0.04
Hackett
369
0.08
Siddle
314
0.04
Tobin
355
0.05
Adams
218
0.05
Denman
391
0.07
Lamb
309
0.07
Noonan
551
0.13
Soper
164
0.04
Williams
106
0.05
Becus
376
0.05
Barfi eld
404
0.07
Young
322
0.13
Lulsgate
494
2.10
Evesham
591
4.84
Aberford
314
1.45
Woburn
188
1.88
P concentrations at equilibrium
0-10 yg P/ml. Langmuir isotherm
correlation coefficients (r) for
each isotherm in this group ranged
from 0.864 to 0.999. Soil properties
not given in this article.
Haysom (1974)
Uniform surface Langmuir equation
Uniform surface Langmuir equation
Uniform surface Langmuir equation
Uniform surface Langmuir equation
Hoi ford et al
(1974)
(Continued)
-------
Table CIO (Continued)
Soil or
Isotherm no.
Smax,P/9 5011
k, ml/ug P
Remarks Reference
Lolsgate
148, 542
30.8, 0.3
Two-surface Langmulr equation.
Evesham
219, 654
36.9, 0.5
Values listed aire for "high-
Aberford
182, 201
14.0, 0.1
energy11 and "low-energy" surfaces.
Weburn
114, 81
- , 0.3
respectively.
Venango
847
Not given
Initial P concentration was 0-3*75
Vljayachandran and
Humatas
684
II
tig P/ml; shaking time was 1 hour.
Harter (1975)
Catallna
683
II
Corozal
468
II
Eutaw
390
II
Agawam
341
II
Davidson
323
.If
Initial P concentration was 0-3.75
Georgevllle
262
.11
Vljayachandran and
Coto
252
ii
yg P/ml; shaking time was 1 hour.
Harter (1975)
Coolvllie
228
CI
Haupun
211
ii
Vallers
175
ii
Putnam
128
ii
Edlna
102
ii
Portsmouth
126
u
Webster
83
ii
Clermont
58
ii
Nacogdoches
55
it
(Continued)
-------
Table CIO. (Continued)
Soil or
Isotherm no. S_,v pg P/g soil k, ml/jig P Remarks Reference
ffidX *
Sao Gabriel-1
-2
Cambai
Durox
Hathaway
Quast
Watts
Anderson
Soil 1
Soil 2
Soil
Soil
Soil
Soil
Soil
Soil 8
Soil 9
-1
-2
-1
-2
73(23)
111(162)
224(100)
300(405)
990(420)
902(1,300)
183, 509
61, 185
127, 156
76, 132
42.6
55.1
50.4
78.3
192.3
87.4
663.5
91.3
304.1
4.8(50.0)
0.1(0.2)
4.7(15.5)
0.1(0.3)
10.9(44.5)
0.1(0.9)
4.6, 0.1
4.5, 0.1
10.6, 0.2
12.0, 0.2
0.37
0.34
0.34
0.30
0.96
0.25
0.09
0.16
0.16
Two-part Langmuir equations used Syers et al. (1973)
for estimation of Smax an(* k.
Nimbers not in ( ) were obtained
from the Langmuir equation for
each of two sites; whereas, the
numbers in ( ) were obtained from
a "rearranged" two-site Langmuir
expression. Initial concentrations
of P were 0-44 pg P/ml; equilibrium
concentrations of P were 0-14 pg P/ml.
Region I is indicated by -1 and
Region II by -2.
Two-surface Langmuir equation
(values listed are for "high-
energy" and "low-energy"
surfaces, respectively.
Uniform surface Langmuir equation
was used. Equilibrium concentra-
tion of P was 0-12 wg/ml.
Hoi ford et al. (1974)
Myszka and Janowska
(1973)
(Continued)
-------
Table CIO. (Continued)
Soil or
Isotherm no.
W, *9 P/9 5011
k, ml/ug P Remarks
Reference
gel A
gel B
gel C
gel D
Walhl
subsoil
Fe-gel -1
-2
LM $2
LM 67
LM 70
Soils
Roselms I
Broughton
Roselms II
4,576
21,760
21.440
36,000
8,832)
70,080)
48,000)
42,400)
1,23
0.21
2.31
3.71
(0.02)
(0.00)
(0.03)
(0.02)
7,840 (20.640) 0.89 (0.01)
Two-site Langmalr expression
was used. Numbers not 1n ( )
Indicate values for term 1, and,
numbers in ( ) are values for
term 2.
Se0§" pretreated; equilibr1um
P concentration was 0-1600 |i
P/ml; 2rsite Langmlur.model
used. Notation as dbbve.
2-
12,380 (16,960) 0.93 (0.01) ^ SeO§" not-pretreated.
20,480
30,080
112
124
105
287
209
249
4.2 pH 6.0 irt 0.1M NaCI
0.05 pH 5.0 In O.IK NaCI
7.11 Jurassic limestones; maximum
6.44 equilibrium P cone, was 3
9.95 pg P/ml. Single-surface
Langmulr equation; 182 hour
equilibration
1.69 Single-surface Langmuir
4.89 equation used. Equilibrium
2.85 P conc. was 0-15,000 |ig P/ml;
(Continued)
Rajan and
Perrott (1975)
Rajan (1975)
McLaughlin
et al. (1977)
Hoiford and
Mattlngly (1975)
McCallister
and Logan (1978)
-------
Table CIO (Continued)
Soil or
Isotherm no.
W, "9 P/9 50,1
k, ml/jjg P Remarks
Reference
Paulding 216
Lenawee 244
Blount 199
Hoytville 258
Soil clay fractions
Roselms I 393
Broughton 323
Roselms II 411
Paulding 455
Lenawee 422
Blount 538
Hoytville 623
Bottom sediments
Independence
1 Dec. 1975 222
Auglaize
'1 Dec. 1975 4,870
Tiffin
1 Dec. 1975 1,930
Independence
24 Mar. 1976 3,580
Auglaize
24 Mar. 1976 4,550
#6 343
m 380
Dicks 237
McDonald 323
4.35
0.80
2.15
1.49
0.86
4.15
1.91
1.09
0.82
7.43
1.63
1.00
0.68
1.55
1.05
1.36
0.06
0.04
0.07
0.09
24 hour equilibration time;
0.01 M CaC^ supporting electrolyte.
McCallister and
Logan (1978)
Single-surface Langmuir equation
used. Equil. conc. range of P
was 0-60 jig P/ml. Six hour
equilibration time; 1:10 soil/
soln. ratio; no supporting electrolyte.
Weir and
Soper (1962)
-------
Table €11. Description of soils used by Ballaux and Peasiee (1975).
Soil Type
Soil property
Alligator
Crlder
Grenada
Pembroke
Zanesvllle
Vertlc
Typic
Gloss1c
MolHc
Typic
Subgroup
Haplaquept
Paludalf
Fragiudalf
Daludalf
Fragiudalf
Clay, %
51.0
18.5
16.9
19.5
16.4
Textural class
slcl
s11
si 1
S11
si 1
Surface area (ethylene
160
54
59
68
51
glycol (m2/g)
8.3
Free Iron oxides*, mg/g
12.3
12.1
10.9
8.8
Organic matter, %
3.8
1.9
1.5
2.3
3.0
pH (1:1/sal: H?0)
6.3
6.7
6.8
7.0
7.0
Phosphorus fractionation,
yg P/g soil
Ali-P
25.2
57.7
15:5
50.0
15.7
Ca-P
91.6
53.3
20.2
39.4
15.3
Fe*P
76.2
71.2
48. V
65.6
31.2
Org-P
142.5
15.0
120^
57.5
80.8
* Although not explicitly stated In the article, free Iron oxides Mere taken as my Fe203/g soil.
-------
Table C12. Description of soils used by Vijayachandran and Harter (1975).
Mechanical analysis Iron Aluminum
Soil series State Subgroup pH
Clay % Silt % Sand % Dithionite Dithionite
(mg/g) (tog/g)
Venango
Ohio
Aerie Fragiaqualfs
4.7
22
49
29
21.5
3.1
Humatas
Puerto Rico
Typic Trophohumults
4.4
76
13
11
90.0
1.2
Catalina
Puerto Rico
Tropeptic Haplorthox
4.9
72
14
14
12.5
1.5
Corozal
Puerto Rico
Aquic Tropudults
4.2
62
20
18
60.0
1.2
Eutaw
Mississippi
Entic Pelluderts
4.7
39
42
19
11.0
2.1
Agawam
New Hampshire
Entic Haplorthods
6.3
7
50
43
11.0
2.4
Davidson
Georgia
Rhodic Paleudults
6.5
28
19
53
35.0
2.6
Georgevilie
N. Carolina
Typic Hapludults
5.5
43
38
19
47.5
2.6
Coto
Puerto Rico
Tropeptic Haplorthox
4.5
40
4
56
70.0
2.5
Coolville
Ohio
Aquic Hapludults
4.6
28
58
14
11.5
1.8
Waupun
Hi scons in
Typic Argiudoll
7.1
21
56
23
11.0
0.9
Vallers
Minnesota
Typic Calciaquolls
7.7
18
12
70
2.5
0.2
Putnam
Mi ssouri
Mollic Albaqualfs
6.0
19
56
25
12.0
0.9
Edina
Iowa
Typic Argialbolls
6.1
11
27
62
9.0
0.7
Portsmouth
N. Carolina
Typic Umbraquults
5.0
13
16
71
2.2
1.8
Webster
Iowa
Typic Haplaquolls
6.8
24
39
37
9.0
0.5
Clermont
Ohio
Typic Ochraqualfs
6.5
21
54
25
9.5
0.7
Nacogdoches
Texas
Rhodic Paleudults
6.7
13
39
48
97.5
3.1
-------
Table C13. Description of soils used by Syers et al. (1973).
Soil property
Soil
Sao Gabriel
Carabal
Durox
Classification
Verttc Argludoll
Argtudoll
Haplohumox
PH
5.2
5.1
3.7
Clay, %
6
25
¦80
Exchangeable AT., raeq/100 g
0.0
0.2
4.3
Oxalate Fe, innoles/100 g
1.2
3.2
2.6
Oxalate Al, mmoles/100 g
0.9
4.0
3.3
CDB Fe, mmoles/100. g*
2.0
10.4
41.4
CDB Al, imroles/TOO: g
2.6
6.7
.1:8.5.
Amorphous.material,
% in «2ynr
T9
30
37
* CDB «Efers to Fe or AT, found Jnthe cttrate-dltMonatertiicarbonate extract
of the soil.
287
-------
Table C14. Description of soils used by-El-Nennah (1975).
Percentage clay minerals
in clay fraction
Soil No. % Clay % Carbonate % Organic Matter Kaolin.ite Illite Montmorillonite Vermiculite
1 2.7 0.5 1.2 75 15 - 10
2 17.2 0.0 4.6 15 85 -
3 63.0 0.0 1.1 - - 100
-------
Table C15. Description of soils used by Holford et al. (1974).
Surface Area
%
%
Soil
Series or group
Location*
% Clay
(ethylene glycol),
CaCO,
Organic C
m2/g
Lulsgate
Lulsgate
1
20.0
130
6.8
4.0
Evesham
Evesham
1
65.1
284
2.7
3.3
Aberford
Aberford
1
18.7
76
6.1
3.6
Woburn 95
Gottenham
1
8.3
so
0
1.2
Watts
Red brown earth
2
27.9
126
0.07
1.3
Arderson
Red brown earth
2
27.4
89
0.09
1.6
Quast
Black earth
2
43.3
306
0.58
1.2
Hathaway
Black earth
2
70.1
389
0.17
0.9
* 1-refers to soils from southern England, 2-refers to soils from eastern Australia.
-------
Table C16. Description of soils used by Myszka and Janowska (1973).
Soil No.
& horizon
Fraction <20pm, %
pH (KC1)
GaCo3,
% of dry weight
Fe203,
% in Tamm extract
AI2O3,
% in Tamm extract
1, A1
14
6.5
.
0.100
0.068
2, A1
24
4.8
0.143
0.077
3, A2
30
5.0
-
0.138
0.068
4, A1
40
5.6
-
0.244
0.104
5, A1
40
5.5
-
0.372
0.202
6, A1
42
6.6
-
0.279
0.274
7, A1
40
7.6
2.27
0.394
0.230
8, AT
-
7.6
8.86
0.125
0.087
9, A1
7.5
18.67
-
-
-------
Table CI7. Description of gels used by Rajan and Perrott (1975).
A1 Specific
SIO2 AI9O3 A1 + Si surface area
Gels % I (molar ratios) m2g-l Crystallinity
A
61.0
21.5
0.29
190
Amorphous
B
38.5
41.0
0.56
278
Amorphous
C
31.2
47.8
0.64
357
Amorphous
D
11.7
66.0
0i87
264
Amorphous +.-
trace of
pseudoboehmite
SiOz, AlgOj, arid surface area are expressed on oven, dry {105 T) basts.
291
-------
Table C18. Description of gels used by Rajan (1975).
Glycol
specific
Si02 A12O3 A1 Fe203 surface area
Mineralogy % % A1 + Si % m^g-l
Predominantly 32.9 33.6 0.54 6.9 168
allophane—small
amount of imogolite
All of the data are expressed on oven dry (105 °C) basis.
292
-------
Table CI9. Description of limestones used by Hoifred and Mattingly (1975).
CaC03, Mg, P, Fe, Surface^ ,
Sample % % % yg/g Area, m g
LM 52
98.5
.23
44
930
1.0
LM 67
98.7
•
W
00
304
3,350
1.0
LM 70
98.9
.22
147
2.130
1,5
293
-------
Table C20. Description of soils used by Weir and Soper (1962).
Soil Description pH % OM CaC03 Total P,
Phosphorus extracted, tig P/q soil
mg P/g soil Water extract NH4F extract NaOH extract H2SO4
extract
ro
vo
4*
No. 6 Orthic Meadow 6.9 5.2 0.7 762
developed on
lacustrine clay
No. 10 Orthic Meadow 7.0 7.3 0.8 1015
developed on
lacustrine clay
Dicks Calcareous 7.5 5.3 11.5 740
Gleyed Rego Black
developed on very
fine sandy loam
deltaic sediments
12.1
59.1
8.5
81.2
135.0
42.1
76.0
105.3
7.2
203
325
300
McDonald Calcareous 7.8 5.3 42.0 670
on silty clay loam
deltaic deposits
2.4
20.2
4.0
322
-------
Table C21. Description of soils and sediments used by McCalllsteir and Logan (1978).
CaC03
Fine Coarse Total Organic- equlv- Amor-
Sand Silt clay clay clay C alent Ph phous S1
Oxalate- Oxalate-
COB-Fe C0B-A1 Fe A1
Soils
Soil clay
Fractions
^-mg/g-
Roselms I
7.0
46.0
12.5
34.5
47.0
1.82
0
6.4
12.1
20.0
2.55
15.5
2.83
Biroughton
6.6
45.1
10.8
37.5
48.3
1.74
0
7.3
10.2
21.2
2.55
6.7
2.75
Roselms 11
10.4
46.8
10.9
31.9
42.8
1.76
0
6.0
11.6
25.0
2.35
13.3
3.33
Lenawee
12.4
53.7
9.5
24.4
33.9
2.13
0
6.6
12.3
17.5
3.00
15.5
5.33
Blount
35.4
42.6
4.5
17.5
22.0
1.47
0
5.4
12.5
32.5
4.70
16.3
3.50
Paulding
5.1
49.5
9.7
35.7
45.4
2.37
0
6.7
10; 9
21.2
2.15
35.0
5.50
Hoytvllle
18.7
42.4
11.1
27.8
38.9
2.24
0
7.1
11.0
16.3
2.15
10.7
4.17
Roselms I
1.66
0
nd
1.00
17.5
1.50
16.50
1.92
Broughton
1.30
0
nd
7.05
15.0
1.33
5.42
1.50
Roselms II
1.54
0
nd
7.56
14.4
1.49
13.10
2.08
Lenawee
2.78
0
nd
5.81
7.5
0.70
7.67
2.17
Blount
2.56
0
nd
5.1$
11.9
1.45
10.10
1.33
Paulding
2.01
0
hd
6.46
15.0
1.15
14.30
2.42
Hoytvllle
2.22
0
nd
4.98
9,7
0.85
6.67
2.00
Bottom Sediments
Independence
0.9$
1 Dec. 1975 88.9
6.0
1.1
4.0
5.1
0.95
12.8
7.3
4.4
0.40
9.2
0.83
Auglaize
6.63
1 Dec. 1975 1.7
57.9
6.5
33.9
40.4
2.07
6.6
6.9
13.8
0.95
26.0
3.00
Tiffin
) Dec. 1975 45.5
31.3
5.0
18.2
23.2
2.04
8il
7.0
3i 17
10.0
0.70
17.7
1.83
Independence
24 Mar. 1976 24.4
37.6
6.8
31.2
38.0
1.91
9.9
7.0
4.72
11.2
1.25
20.7
2.67
Augulalze
24 Mar. 1976 3.4
47.5
8.8
40.3
49.1
1.82
6.4
6.9
6.22
13.a
1.40
27.1
3.50
-------
1 / s.
Table C22. Regression parameters from phosphate adsorption isotherms using S - Smax - y (q) as
the regression model (Smax and - ^ are regression coefficients).
Isotherm No.
or Soil
Smax»
yg P
g soil
ml
Standard errors
1 V9 p k _
k* ml K* ng P
sQ S
^'C
"5T
¦>max
Reference
5
922
-0.078
12.8
0.88
165
144
0.021
6
525
-0.065
15.4
0.99
38.7
37
0.008
7
478
-0.05
20.0
0.79
110.3
71
0.016
8
1,291
-0.12
8.3
0.72
318
301
0.055
9
553
-0.16
6.2
0.79
104
81
0.047
10
398
-0.055
18.2
0.78
'44
34
0.017
11
383
-0.15
6.7
0.80
67
36
0.031
12
278
-0.22
4.5
0.84
36
32
0.053
13
324
-0.082
12.2
1.90
31
28
0.016
14
302
-0.153
6.5
0.85
35
31
0.038
15
284
-0.29
3.4
0.86
30
27
0.068
16
2,009
-0.35
2.9
0.60
483.0
269
0.109
17
1,936
-0.36
2.8
0.78
384
390
0.110
18
1,517
-0.25
4.0
0.46
533
278
0.105
19
343
-1.16
0.86
0.40
105
76
0.815
20
388
-1.55
0.65
0.89
44.6
35
0.322
21
343
-1.76
0.57
0.89
38.8
30
0.365
22
328
-2.26
0.44
0.83
45.0
34
0.585
23
346
-3.92
0.26
0.88
37.0
33
0.838
24
340
-3.81
0.26
0.88
36.8
31
0.807
25
333
-2.59
0.39
0.95
21.7
17
0.33
26
313
-2.47
0.40
0.89
31.5
24
0.48
27
265
-2.08
0.48
0.79
39.6
27
0.62
Munns and Fox (1976)
Holford and Mattingly (1976)
Hope and Syers (1976)
Singh and Tabatabai (1976)
(Continued)
-------
Table C22. (Continued)
Standard errors
IS°oreSoi?°" SmaX' g^soTT ' P i!Sr' k' Sg P r2 Ssmax Reference
28
253
-2.44
0.41
0.88
26.2
18
0.52
Singh and Tabatabal (1976)
29
251
-3.94
0.25
0.90
22.5
18
0.77
II
30
205
-7.84
0.13
0.80
24.0
24
2.24
II
31
710
-2.40
0.42
0.98
20.1
21.4
0.19
Edzwald, Toenslng, and
32
82
-2.20
0.45
0.33
19.8
16.2
1.56
Leung (1976)
33
2,331
-4.69
0.21
0.89
106.5
111.6
0.67
II
34
72.4
-0.035
28.6
0.002
18.2
7.8
0.27
II
35
54
-6.17
0.16
0.88
12.4
14.5
1.63
II
36
152
-2.96
0.34
0.87
9.5
9.65
0.66
II
37
603
-0.49
2.04
0.64
95
74
0.213
II
38
629
-0.314
3.18
0.87
58
33
0.069
II
40
708
-2.11
0.47
0.98
22
22
0.185
II
43
2,332
-3.06
0.33
1.00
21
25
0-11
II
44
2,298
-4.69
0.21
0.83
137.9
143.7
0.87
II
45
2,369
-2.54
0.39
0.93
100.0
99.4
0.39
II
49
638
-0.505
1.98
0.15
174
730
0.829
Barrow (1972)
50a
1,040
-0.074
13.5
0.84
137
132
0.019
tl
50b
224
-0.116
8.62
0.92
22
24
0.025
U
50c
451
-0.042
23.8
0.89
44
51
0.010
II
50d
633
-0.099
10.1
0.72
103
154
0.044
II
5Qe
1,385
-0.110
d.09
0.91
143
197
0.024
If
51
2,196
-0.031
32.3
0,58
527
250
0.013
Ryden, McLaughlin, and
52
32,900
-0.011
90.9
0.55 4,840 2
,230
0.005
Syers (1977a)
52a
3,330
-0.016
62.5
0.69
270
143
0.006
II
(Continued)
-------
Table C22. (Continued)
Standard errors
IS°oreSoil° Smax* 9^soi 1 " P-k' ug P r2 Ss'| Ss,nax "1 Reference
57
4,420
-0.496
2.02
0.87
494
380
0.112
58
3,030
-0.491
2.04
0.79
368
268
0.147
59
2,890
-0.420
2.38
0.91
196
143
0.078
60
2,490
-0.281
3.56
0.82
263
172
0.077
61
1,840
-0.289
3.46
0.82
146
98
0.077
62
1 ,800
-0.403
2.48
0.85
131
90
0.097
63
2,150
-0.398
2.51
0.87
£24
146
0.091
64
1,480
-0.267
3.75
0.58
282
156
0.133
65
1,660
-0.357
2.80
0.89
146
94
0.071
66
1,240
-0.184
5.43
0.85
140
81
0.044
67
945
-0.225
4.44
0.79
143
86
0.068
68
461
-0.367
2.72
0.81
67
43
0.103
69
397
-0.306
3.27
0.78
58
35
0.095
70
347
-0.498
2.01
0.81
38
30
0.140
71
318
-0.557
1.80
0.78
42
30
0.171
72
299
-0.886
1.13
0.82
37
28
0.240
73
275
-0.158
6.33
0.62
76
43
0.072
74
292
-0.109
0.90
0.90
28
23
0.219
75
245
-0.822
1.22
0.83
32
23
0.214
76
220
-0.935
1.07
0.84
29
22
0.234
77
206
-0.719
1.39
0.80
36
24
0.206
78
2,080
-0.016
62.5
0.69
517
296
0.006
79
1,300
-0.083
12.0
0.85
172
139
0.020
80
278
-0.088
11.4
0.91
26
21
0.016
81
171
-0.109
9.17
0.85
17
16
0.026
Ryden and Syers (1975)
-------
Table £23. Descriptions of soils and experimental parameters used by Minns and Fox (1976) for from
whose Isotherms Langmulr parameters given in Table 3 were computed.
Isotherm Soil or Equil.
No. adsorbent P conc.
used Soln:so11 Supporting pH Shaking range, ug^P
ratio Electrolyte Control Time ml
Remarks
5
Hal11 soil
10:1
1 mM CaCl9
Ho
6 days
0-3
6
Molokal soil
10:1
1 mM CaCl,
No
6 days
0-3
7
tyaklawa soil
10:1
1 rnff CaCl,
No
6 days
0-3
8
Kula
10:1
1 mJT CaCl,
1 raffCaCl-
No
6 days
0-3
9
Hahlawa soil
10:1
No
6 days
0-3
Soil properties:
Soil type*
Organic
pHt H#)t carbon
haken twice daily
n centrifuge tubes,
oluene added.
Mineralogy
Molokal sllty loam
Typlc Torrox,
Isohypothermic
5.7
Wahiawa sllty clay
Tropeptlc Eutrustox,
1sothermic 4.7
-I-
30 1.0
35 1.7
Kaollnite
sesquioxides
KaoltMte, hematite,
mica
Hal11 gravelly sllty clay
Typlc Glbbslhumox,
isothermlc 5*1
6ibbsite, goethlte,
33 3.9 Kaolihite, amorphous
Kula loam
Typlc Eutrandept,
media, isothermlc
5.8
Amorphous Fe and
64 9.7 A1 oxides
* Samples taken from Hawaiian Islands. All samples from 0-15 cm depth
except Molakal soil, 20-40 cm.
t pH measured in 1 mM CaCl2» % H2O at approximately 0.1 bar suction.
-------
Table C24. Description of soils and experimental parameters used by Holford and Mattingly (1976)
and Russell (1963) from whose isotherms Langmuir parameters were computed.
Isotherm Soil Equil.
No. P conc.
Soln:soil Supporting pH Shaking range, pg P
ratio Electrolyte Control Time ml Remarks
10
Castle Cary
No experimental
11
Longborough
methods given in
12
Andoversford-
article
low P
13
Dunkirk
14
Sherborne
15
Andoversford-
high P
Soil Properties:
P applied
%
%
%
ymoles/A
p.p.m.
P
Soil
in field
kg/ha
%
clay
pH
Organic
matter
CaC03
Total
P
CaCl^
0.5N-
Acetic
Acid
Acetic
acid-
sodium
acetate
0.5M-
NaHCO-j
1%
Citric
acid
Sherborne
307
35.3
8.0
6.2
15.5
0.123
1.25
43.1
3.8
23.6
158
Andoversford
142
274
29.0
7.9
8.0
5.5
5.6
8.6
11.8
0.098
0.107
1.19
2.08
24.8
48.0
3.8
6.0
16.2
29.0
130
235
Longborough
175
40.5
8.0
6.3
12.6
0.119
0.86
32.4
3.4
23.8
230
Dundi rk
153
35.7
7.8
5.3
7.6
0.117
0.31
16.0
3.0
11.3
120
Castle Cary
44
38.5
7.5
5.7
2.2
0.?70
1.04
457.0
6.0
31.0
780
-------
Table C25. Experimental parameters used by Hope and Syers (1976) from whose Isotherms Langmuir
parameters were computed.
Isotherm
No.
Soil
So1n:so11
ratio
Supporting pH
Electrolyte Control
Reaction
Time
Equll.
P conc.
range, ug^P
Remarks
16
17
18
Ramiha soil
Ramiha soil
Ramlha soil
6:1
10:1
40:1
0.1 M NaCI
0.1 K NaCI
0.1 H NaCI
40 hrs.
40 hrs.
40 hrs.
0-6
0-6
0-6
Kg. CI2 added.
End-over-end
tumbling of polycarbon-
ate centrifuge tubes.
Soil properties; Not given
-------
Table C26. Experimental parameters used by Singh and Tabatabai (1976) from whose isotherms Langmuir
parameters were computed.
Isotherm Soil Equil.
No. P cohc.
Soln:soil Supporting pH Shaking range, ^9 P
ratio Electrolyte Control Time ml Remarks
19
Webster soil
10
1 0.01 M
CaSOA
Ca(N03)2
No
24
hrs.
0-30
Plastic centrifuge
20
Webster soil
10
1 0.01 M
No
24
hrs.
0-30
tubes shaken on
21
Webster soil
10
1 0.01 M
NaCl
No
24
hrs.
0-30
a reciprocating
22
Webster soil
10
1 0.01 M
CaCl2
No
24
hrs.
0-30
shaker.
23
Webster soil
10
1 H2?
No
24
hrs.
0-30
24
Webster soil
10
1 0.01 M
NaHC03
No
24
hrs.
0-30
25
Ida soil
10
1 0.01 M
CaS04
No
24
hrs.
0-30
26
Ida soil
10
1 0.01 M
Ca(N03)2
No
24
hrs.
0-30
27
Ida soil
10
1 0.01 R
NaCl
No
24
hrs.
0-30
28
Ida soil
10
1 0.01 M
CaCl2
No
24
hrs.
0-30
29
Ida soil
10
1 H2O
No
24
hrs.
0-30
30
Ida soil
10
1 0.01 M
NaHC03
No
24
hrs.
0-30
Soil properties:
Phosphorus
Soil pHt Total Organic Water- Olsen-P Bray-P Free
(HC1O4 dig.) soluble (NaHC03) (NH4F) Fe*
ppm
Webster 6.1 589 102 10.4 32 39 0.15
Ida 8.0 774 42 0.5 3 2 0.75
tpH determined in H2O; soil: H2O = 1:2.5
*Citrate-dithioncte-bicarbonate extract
-------
Table C27. Experimental parameters used by Edzwald et al. (1976) from whose Isotherms Lanqmuir
parameters were computed.
Isotherm
No.
Adsorbent Soln:soil Supporting
ratio Electrolyte
Equll.
P conc.
pH Shaking range, ug P
Control Time ml
Remarks
31 Montmorlllonlte
32 Kaolinite
33 1111te
34 Kaolinite
35 Kaolinite
36 Kal Unite
37 Montmorlllonlte
38 Montmorlllonlte
40 Montmorlllonlte
43 IlUte
44 II lite
45 IlUte
Not given 0.002 M
Not given NatttXh
Not given NaHCOs
Not given NaHCOj
Yes
Yes
Yes
Yes
Not given NaHC03 + 0.03 M Yes
N92SO4
Not given NaHCOs 4 0.5 M Yes
NaCl
Not given NaHC03 +0.03 M Yes
Na2S04
Not given KaHC03 + 0.5 M Yes
NaCl
Not given NaHCflo * 0.5 H Yes
NaCl
Not given NaHCOs + 0.03 M Yes
Na£S04
Not given NaHfth + 0.03 M Yes
Na2S04
Not given NaHCOs + 0.5 M Yes
NaCl
Adsorbent properties:
Clay
24 hrs.
24 hrs.
24 hrs.
24 hrs.
24 hrs.
24 hrs.
24 hrs.
24 hrs.
24 hrs.
24 hr$.
24- hrs.
24 hrs.
0-20
0-20
0-20
0-20
0-20
0-20
0-20
0-20
0-20
0-20
0-20
0-20
Buffered systems with
NaHC03. Erlenmeyer
flasks used. Tempera-
ture was 28°C.
Acid extractable (HCI-H2SO4)
Fe» rag/g Al, mg/g
Kaol1n1te-API 83 0.028
Montmorl11on1te-API #21 0.171
Illite-API #36 2.38
0.14
0.68
2.45
-------
Table C28. Experiments! parameters used by Barrow (1972) from whose isotherms Langmuir parameters
were computed.
Isotherm Soil Equil.
No. P conc.
Solnrsoil Supporting pH Shaking range, pg P
ratio Electrolyte Control Time ml Remarks
49
50a
51b
50c
50d
50e
Soil
1
Soil
1
Soil
2
Soil
2
Soil
3
Soil
3
Soil
P
H2O
0.02 M CaClo
H2O
0.02 M CaCl2
H20
0.02 M CaCl2
No
24
hrs.
0-0.6
No
24
hrs.
0-0.6
No
24
hrs.
0-0.6
No
24
hrs.
0-0.6
No
24
hrs.
0-0.6
No
24
hrs.
0-0.6
Temperature was 25°C.
A reciprocating shaker
was used.
pH in
Number Location 0.01 M
CaCl
Total
N
Free
Fe
(per cent) (per
cent)
Free
A1
(per
cent)
Exchangeable
Na K Ca Mg
(me./lOO g)
Cation
Exchange
Capacity
(me./lOO g)
1 Robertson,
N.W. Wales
2 Mungong,
W. Australia
3 Manjimup,
W. Australia
4.2
0.38
5.2
1.2
0.17
0.18
2.12
1.44
16.1
5.2
0.16
0.8
0.3
0.15
0.21
2.87
1.11
10.3
6.2
0.25
2.1
0.5
0.50
0.83
11.7
4.9
26.3
-------
Table C29. Experimental parameters used by Ryden et al. (1977a,b) from whose Isotherms Langmulr
parameters were computed.
Isotherm
No.
Adsorbent
Soln:soil
ratio
Supporting
Electrolyte
pH
Control
Shaking
Time
Eqtill.
P eonc.
range, tig P
ml
Remarks
51
52
S2a
Okaihau
Fe-gel
Goethlte
40:1 0.1 M NaCl No 192 hrs.
40:1 0.1 M NaCl, pH7 Yes 192 hrs.
40:1 0.1 R NaCl, pH7 Yes 192 hrs.
0-8
Temperature was 24°C.
Reciprocating shaker
used to agitate poly-
carbonate tubes.
HgCl? (147 ymole/1)
added to prevent
microbial growth.
Synthetic goethl te arid
Fe-gel.
Absorbent properties:
1. Okaihau soil-see description at Isotherm No. 64.
2. Fe-gel , Ng surface, area-280 m2g-l; amorphous to x-rays.
3. Goethlte-T to 0;1 m fraction used after aging 10 months
at room temperature.
-------
Table C30., Experimental parameters used by Ryden and Syers (1975) from whose isotherms Langmuir
parameters were computed.
Isotherm
Soi 1
Equil.
No.
P conc.
Soln
soil Supporting
PH
Shaking
range, pg P
ratio Electrolyte
Control
Time
ml
Remarks
57
Egmont
40
1 10~2M CaCl2
No
40
hrs.
0-10
End-over-end shaker
58
Egmont
40
1 10-1R NaCl
No
40
hrs.
0-10
used at 23°C. HgCl2
59
Egmont
40
1 10-3M CaCl?
No
40
hrs.
0-10
(40 g/ml) added to
60
Egmont
40
1 3x1 O^M NaCl
No
40
hrs.
0-10
each tube.
61
Egmont
40
1 10-4m CaCl2
No
40
hrs.
0-10
62
Egmont
40
1 10-4M NaCl or
No
40
hrs.
0-10
"20
63
Okaihau
40
1 10"2m CaCl2
No
40
hrs.
0-10
64
Okaihau
40
1 10-lM NaCl
No
40
hrs.
0-10
65
Okaihau
40
1 10-3m CaClg
No
40
hrs.
0-10
66
Okaihau
40
1 10-4m CaCl2
No
40
hrs.
0-10
67
Okaihau
40
1 H20
No
40
hrs.
0-10
68
Porirau
40
1 10"2m CaCl2
No
40
hrs.
0-10
69
Porirau
40
1 10-lM Na or
10-3m CaClo
No
40
hrs.
0-10
70
Porirau
40
1 3x1 O^M NaCl
No
40
hrs.
0-10
71
Porirau
40
1 10-4M CaCl2
No
40
hrs.
0-10
72
Porirau
40
1 lO-^M NaCl or
h2o
No
40
hrs.
0-10
73
Waikakahi
40
1 10-2m CaCl2
No
40
hrs.
0-10
74
Waikakahi
40
1 10-3m CaCl2
No
40
hrs.
0-10
75
Waikakahi
40
1 10-^M CaCl2
No
40
hrs.
0-10
76
Uaikakahi
40
1 3x10^2M NaCl
or H2O
No
40
hrs.
0-10
(Continued)
-------
Table C30. (Cpnflnued)
Isotherm
No.
Soil
Equ11.
P conc.
Soln:soil
ratio
Supporting
Electrolyte
pH
Control
Shaking
Time
range, ug P
ml Remarks
77 Waikakahl
78 Egtnont
79 Okaihau
80 Porlrau
81 Waikakahl
40:1
40:1
40:1
40:1
40:1
10-lH NaCl
10-2R CaCl2
10-2R CaCl2
10-2S CaCl?
ip-25 CaCl2
No
No
No
No
No
40 hrs.
40 hrs.
40 hrs.
40 hrs.
40 hrs.
0-10
0-1
0-1
0-1
0^1
Soil properties:
Exchangeable
COB
Crystalline
Short-range
COB Order
Surface
Soil Horizon
pH
Ca A1
(nmoles/100 g)
CaCOa
(%)*
Fe A1 Fe A1
(nmoles/100 g) (mraoles/100 g)
Clay
(%)*
area
(m*/g)
fgmOnt BC
7.1
1.17 1.03
0
21
78 19.5 133
41
52
Gkafhau B2
5.0
0.00 0.57
0
139
124 5.2 18.0
31
64
Por1rua fine B]
5.0
0.40 0.72
0
7.3
10.0 3.3 5.6
15
9.2
Waikakahl BjCa
7.7
n.d. 0.00
27
17.6
8.0 4.3 4.6
n.d.
17.8
(Continued)
* Data from New Zealand Soil Bureau (1968).
-------
Table C30. (Continued)
Isotherm Soil Equil.
No. P cone.
Soln:soil Supporting pH Shaking range, uq P
ratio Electrolyte Control Time ml Remarks
Soil properties (Continued)
Effect of support media on supernatant pH values
(average values over the isotherm)
pH values in
Soil 10"Ca 10"3m Ca 1(Hm Ca 1(Hm Na 3x10-3 Na lO'^M Na Water
Egmont 6.78
Okaihau 4.74
Porirua 4.44
Waikakahi 7.97
6.79 7.28 6.70
4.84 5.77 5.05
4.79 5.36 4.55
7.91 8.13 8.05
6.83 7.33 7.34
5.62 -- 6.33
4.88 5.90 5.79
8.09 -- 7.99
-------
Table C31. Data used for calculating Langmulr constants (listed 1n Table C22)
from Isotherms.
Isotherm
No.
Description
P sorbed,
ug P/g soil
Equll. conc. of P,
ug P/ml
S/C,
ml/g soil
Munns and Fox (1976)
(5) Hallll soil
(6) Molokai soil
(7) Wahiawa soil
(8) Kula soil
(9) Wahiawa soil
110
295
500
1,000
50
300
500
50
180
300
400
600
100
550
1 ,Q00
1,200
100
200
300
450
600
0.1
0.037
0.163
1.215
.0067
.10
.702.
.0058
.043
.186
.500
1.49
.0149
.0702
.289
2.65
.0316
.120
.295
.712
1.310
11,000
8,000
3,100
820
7,500"
3,000
.710
£,600
4,200
1,600
800
400
6,700
7,800
3,500
450
3,160
T,700
1,000
630
460
Holford and Mattlngly (1976)
(10) Sherborne Series 220 0.060 3,660
Castle Cary 260 0.120 2,160
294 0.240 1,220
325 0.360 900
435 1.280 340
(continued)
309
-------
Table C31. (Continued)
Isotherm
P sorbed,
Equil. conc. of P,
s/c,
No. Description
ug P/g soil
yg P/ml
rnl/g soi
Holford and Mattingly (1976)
(11) Longborough
122
0.060
2,030
158
0.120
1,310
204
0.280
720
328
1.240
260
435
2.720
160
(12) Andoversford
80
0.080
1,000
116
0,160
720
154
0.400
380
179
0.460
380
289
2.160
130
(13) Dunkirk soil
106
0.040
2,650
146
0.060
2,430
187
0.136
1,370
216
0.220
980
324
0.840
380
(14) Sherborne
111
0.080
1,380
146
0.160
910
188
0.320
580
214
0.520
410
314
1.600
190
(15) Andoversford
107
0.160
660
142
0.322
440
179
0.640
280
204
0.960
210
289
2.68
100
Hope and Syers (1976)
(16) Solution:Soil 133 .06 2,200
ratio 5:1: 400 .09 4,400
972 .22 4,400
1,178 .47 2,500
1,389 .83 1,700
(continued)
310
-------
Table C31. (Continued)
Isotherm P sorted, Equll. conc. of P, S/C,
No. Description ug P/g soil ug P/ml ml/g soil
Hope and Syers
Solut1on:So1l
1,680
1.78
940
ratio 5:1:
1,851
2.83
650
2,022
3.83
530
2,191
5.22
420
Solution:Soil
200
.06
3,r300
ratio 10:1:
356
.08
4,500
489
.10
4,900
956
.35
2,700
1,956
3.89
500
Solut1on:So1l
43
.04
1,100
ratio 40:1:
238
.06
4,000
541
.11
4,900
643
.16
4,000
930
.43
2,200
1,297
1.57
830
1,557
2.53
620
1,784
4.42
400
1 *914
5.83
330
Singh and Tabatabai (T976)
(19) CaS04 100 .562 180
Webster soil 191 1.410 140
265 3.330 80
339 6.410 53
395 9.740 40
(20) Ca(N0,)? 97 .481 200
J 189 1.732 110
255 4.444 58
322 8.111 40
391 12,010 33
(continued)
311
-------
Table C31. (Continued)
Isotherm
P sorbed,
Equil. conc. of P,
s/c,
No.
Description
pg P/g soil
ug P/ml
ml/g soi
Singh and
Tabatabai (1976)
(21)
NaCl
95
.624
152
174
2.434
71
241
5.478
44
303
10.816
28
343
15.849
22
(22)
CaCl,
92
.811
113
c
166
3.421
49
230
7.305
32
283
11.700
24
333
17.783
19
(23)
H,0
87
1.233
71
c
159
4.217
38
226
9.165
25
263
12.328
21
326
20.000
16
(24)
NaHCO,
87
1.233
71
159
4.217
38
224
9.742
23
283
16.876
17
315
18.738
17
(25)
Ida Soil
91
.924
98
CaSO,
169
3.082
56
230
6.989
33
276
12.271
22
311
17.557
18
(26)
Ca(N0,)P
90
.950
95
0 C
163
3.080
53
214
8.360
26
267
12.430
21
306
18.012
17
(continued)
312
-------
Table C31. (Continued)
Isotherm
P sorbed,
Equtl. conc. of P,
s/c,
No.
Description
ug P/g sol 1
ug P/ml
ml/g soil
(27)
NaCl
90
1.000
90
156
4.969
31
202
10.000
20
243
15.849
15
283
.22.103
13
(28)
CaCl,
88
1.227
72
150
5.000
30-
194
10.700
18
226
16.939
13
25:7
25.770
10:
(29)
H,0
85
1.896
45.
c
137
6.150
22
185
13.421
14
213
20.100
11
238
26.438
9
(30)
NaHCO,
65
3.415
19
J
102
10.000
10
133
18.012
7
161
23.263
7
183
31.623
6
Edzwald, Toenslng, and Leung (1976)
(31) Montmor1llon1te 310 1.78 174
+ NaHCO, 380 2.89 131
J 470 5.00 94
560 9.32 60
620 13.54 46
(32) Kaollnlte 44.0 2.22 20
+ NaHCO., 44.0 4.44 10
* 44.0 7.1 6
66.0 9.32 7
88.0 14.43 6
88.0 21.0 5
(continued)
313
-------
Table C31. (Continued)
Isotherm
P sorbed,
Equil. conc. of P,
s/c,
No.
Description
pg P/g soil
ug P/ml
ml/g soil
Edzwald, Toensing, and Leung (1976)
(33)
ITlite
1,130
4.22
268
+ NaHCO,
1,240
5.66
220
1,380
7.99
173
1,750
10.99
160
1,690
13.32
127
1,750
15.98
110
1,840
17.32
106
1,950
19.76
99
(34)
Kaolinite
69
0.86
80
no salt
69
2.86
24
51
4.3
12
64
6.9
9
55
7.1
8
109
8.6
13
80
9.4
9
69
13.1
5
80
17.4
5
(35)
Kaolinite +
68.6
2.3
3.2
0.03 M Na,S0,
97.1
5.1
5.4
— C 4
114
13.1
11.4
137
18.0
12.0
(36)
Kaolinite +
80
3.8
21.0
0.5 M NaCl
103
5.0
20.6
120
12.5
9.6
129
16.9
7.6
137
21.0
6.5
(37)
Montmorillonite
286
0.6
477
+ 0.03 M Na9S0A
400
0.7
571
— L 4
457
2.6
176
514
4.6
112
657
7.4
89
(continued)
314
-------
Table C31. (Continued)
Isotherm
P sorbed,
Equll. conc. of P,
S/C,
No.
Description
ug P/g soil
ug P/ml
ml/g soi
Edzwald,
Toenslng* and Leung (1976)
(38)
Montmor1llon1te
314
0.3
1,047
+ 0.5 M NaCl
486
2.3
211
571
4.2
136
629
8.6
73
671
13.1
51
(40)
Montraorlllonlte
322
1.70
189
+ no salt
400
2.82
143
486
5.14
95
571
9.43
60
637
13.7
46
(43)
Illlte +
1,257
3.6
353
0.03 M Na-SOi
1.600
6.8
234
— C H
1,800
10.4
173
1,896
12.5
152
1,966
17.1
115
(44)
imte +
1,120
4.18
268
no salt
1,210
5.70
212
1,320
7.98
165
1,740
10.83
161
1,670
13.49
124
1,730
15.96
108
1,820
17.39
105
1,950
19.81
98
(45)
Illlte +
1,320
3.04
434
0.5 M NaCl
1,600
6.58
243
1,800
9.69
194
2,060
14.54
142
2,120
18.81
113
(continued)
3J5
-------
Table C31. (Continued)
Isotherm
No.
Description
P sorbed,
ug P/g soil
Equil. conc. of P,
ug P/ml
S/C,
ml/g soil
Barrow (1972)
(49) Soil 1--
no Ca2+
86
156
241
379
0.01
0.17
0.24
0.53
860
918
1,004
715
(50a) 5oil 1 —
0.02 M Ca2+
(50b) Soil 2—
no Ca2+
241
397
517
724
1,000
48
96
152
193
0.02
0.06
0.08
0.19
0.40
0.03
0.11
0.23
0.51
12,050
6,616
6.462
3,810
2,500
1
600
873
661
378
(50c) Soil 2-
0.02 M Ca2+
(50d) Soil 3«
no Ca2+
(50e) Soil 3—
0.02 M Ca2+
152
207
303
400
121
241
379
483
121
397
741
1,000
0.02
0.04
0.11
0.18
0.03
0.05
0.15
0.26
0.01
0.05
0.12
0.24
7,600
5,175
2.754
2,222
4,033
4,820
2,526
1,858
12,100
7,580
6,175
4,166
Ryden, McLaughlin, and Syers (1977)
(51) Okaihau- 2,742 7.31 375
equilibrium 2,583 5.26 491
2,171 1.83 1,186
1,669 0.57 2,928
1,314 0.18 7,300
914 0.02 45,714
(continued)
316
-------
Table C31. (Continued)
Isotherm P sorbed, Equll. conc. of P, S/C,
No. Description ug P/g soil »g P/ml ml/g soil
Etyden, McLaughlin, and Syers (1977)
(52) Fe-gel
C52a) Synthetic
goethite
Hyden and Syers (1975)
(57) Aa
(58) Ab
(59) Ac
(60) Ad
(continued)
38,400
4.98
7,710
36,053
3.02
11,900
32,700
1.78
18,400
29,200
0.75
38,900
25,600
0.32
80,000
21,300
0.02
1,060,000
3,630
7,09
512
3,420
3.43
997
3,140
1.14
2,754
2,930
0.46
6,369
2,560
0.05
51,106
575
0
1,759.5
.29
6,065
2,162
.58
3,730
2,921
1.45
2,041
3,829.5
4.21
1,467
4,60G
9.57
481
1,529.5
.435
3,500
1,725
1.02
1,690
2,438
2.55
956
2,783
4.50
618
3,162.5
7.54
419
1,529.5
.435
3,500
1,897.5
1.02
1,860
2,415
2.8
863
2,587.5
3.87
668
2,932.5
7.15
410
1,322.5
0.29
4,560
1,725.0
1.02
1,690
2,070.0
2.12
976
2,369.0
4.15
570
2,679.5
7.U5
380
317
-------
Table C31. (Continued)
Isotherm
P sorbed,
Equil. conc. of P,
s/c,
No. Description
ug P/g soil
wg P/ml
ml/g so1
Ryden and Syers (1975)
(61) Ae
1,150.0
0.44
2,600
1,380.0
1.45
950
1,633.0
3.05
535
1,782.5
4.50
396
1,897.5
6.38
297
(62) Af, g
1,092.5
0.58
1,880
1,380.0
2.03
680
1,552.5
3.63
428
1,725.0
5.66
305
1,840.0
7.40
249
(63) Ba
950
.29
3,175
1,410
1.16
1,215
1,670
2.09
799
2,130
6.09
350
2,240
9.57
234
(64) Bb
750
.29
2,586
1,120
1.02
1,100
1,570
4.21
373
1,690
6.24
270
1,840
9.48
140
(65) Be
775
.29
2,672
1,120
1.02
1,100
1,410
3.05
467
1,550
4.93
315
1,770
9.57
185
(66) Be
570
.145
3,930
830
.67
1,240
1,121
3.19
351
1,240
5.95
208
1,350
8.99
150
(67) Bg
390
.145
2,690
600
.73
822
770
2.09
368
950
4.06
234
1,060
7.4
143
(continued)
318
-------
Table C31. (Continued)
Isotherm
P sorbed,
Equfl. conc.of P,
S/<
No. Description
wg P/g soil
ng P/ml
ml/g !
Ryden and Syers (1975)
(68) Ca
185
.22
841
263
.73
360
359
2.18
165
424
4.35
97
520
9.57
54
(69) Cb.c
179
.23
786
25:1
1.02
246
335
2.84
118
389
5.22
75
442
8.99
49
(70) Cd
173
0.44.
394
203
1.02
199
263
2.09
126
311
3.48
89
353
6.09
58
(71) Ce
149
0.44
340
191
1.29
148
239
2.61
92
293
5.16
57
341
8.85
39
(72) Cf,g
120
0.54
222
173
1.74
99
215
3.19
67
263
5.74
46
311
9.72
32
(73) Da
91
0.07
1,300
136
0.44
309
223
1.89
118
282
4.06
69
354
8.41
42
(.74) Dc
286
9.12
31
250
6.18
40
191
2.79
68
145
1.32
110
100
0.53
189
(continued)
319
-------
Table C31. (Continued)
Isotherm
P sorbed,
Equil. conc. of P,
s/c,
No. Description
yg P/g soil
ug P/ml
ml/g soi'
Ryden and Syers (1975)
(75) De
255
9.71
26
227
6.76
34
173
3„23
54
132
1.32
100
91
0.44
207
(76) Dd,g
223
8.09
28
191
5.15
37
150
2.65
57
109
1.32
82
64
0.35
182
(77) D,b
227
9.41
24
191
6.47
30
154
3.53
44
91
0.88
103
56
0.24
233
(78) Aa
2,581
0.922
2,800
2,194
0.469
4,680
1,581
0.172
9,190
1,032
0.034
30,300
613
0.006
102,000
(79) Ba
1,372
0.906
1,510
989
0.297
3,330
798
0.188
4,240
574
0.078
7.360
383
0.031
12,400
(80) Ca
281
0.938
299
225
0.438
514
188
0.219
858
141
0.109
1,290
(81) Da
169
0.781
216
131
0.406
323
113
0.281
402
94
0.156
603
66
0.063
1,050
320
-------
Table C32. Freundllch constants found 1n literature.
Soil or
Isotherm no.
Freundllch
K
n
Remarks
Reference
Illinois River,
>0.05nm Spoon
River, >0.05ym
, 0.185
0.321
Equlllbrulm P concentrations were
0-10 pgP/ml. Membrane filter used
in separating solids from solution.
pH was controlled by adding HC1;
aerobic conditions throughout.
Wang (1974)
Kao11n1te
0.562
0.388
Low and Black (1950)
------- |