United States
Environmental Protection
Agency
Robert S. Kerr Environmental
Research Laboratory
Ada OK 74820
Research and Development
EPA/600/S6-88/001 Apr. 1988
&EPA Project Summary
Treatment Potential for 56 EPA
Listed Hazardous Chemicals in
Soil
Ronald C. Sims, William J. Doucette, Joan E. McLean, William J. Grenney,
and R. Ryan Dupont
The full report presents information
on the quantitative evaluation of the
treatment potential in soil for 56
substances identified as hazardous by
the U.S. Environmental Protection
Agency (EPA). The 56 chemicals eval-
uated were organized into four categor-
ies of substances: (1) polynuclear
aromatic hydrocarbons (PAH), (2)
pesticides, (3) chlorinated hydrocar-
bons, and (4) miscellaneous chemicals.
Treatability screening studies were
conducted to determine: (1) degrada-
tion rates, (2) partition coefficients
among air, water, soil, and oil phases,
and (3) transformation characteristics.
The quantitative information developed
for a subset of the tested chemicals was
input into two mathematical models
specifically adapted to describe the
treatment process. Results of fate and
transport predictions of the models
were compared with laboratory and
literature results in order to evaluate the
ability of the models to predict the
behavior of the selected chemicals in
a soil system.
The experimental approach used in
this study was designed to characterize
degradation, immobilization, and
transformation potentials for the haz-
ardous substances evaluated. Biodeg-
radation rates were determined exper-
imentally by applying the chemical of
interest to a soil microcosm and mon-
itoring concentration over time. A plot
of the disappearance of a constituent
versus treatment time provided the
following information: (1) reaction rate
constant, and (2) half-life in soil (first
order reaction assumed). Special
methods were employed to determine
biodegradation rates corrected for
volatilization losses for the constitu-
ents tested. Losses were also deter-
mined in microbially inactive soil/
substance controls for a subset of
substances to indicate contribution to
degradation of abiotic (e.g., hydrolysis,
oxidation, etc.) processes. Transport
data were developed using calcula-
tional procedures based on structure-
activity relationships (SARs). To deter-
mine partition coefficients among soil,
air, oil, and water phases one set of
studies was conducted using the radio-
labeled compound 7,12-dimethylbenz-
(a)anthracene (DMBA) in order to
evaluate the potential for formation of
biochemical intermediates during the
biodegradation of DMBA, and to deter-
mine the extent of incorporation of the
chemical into soil organic matter.
Treatability data generated in this
investigation were entered into the Soil
Transport and Fate Data Base deve-
loped as part of a concurrent EPA-
funded study.
This Project Summary was devel-
oped by EPA's Robert S. Kerr Environ-
mental Research Laboratory. Ada. OK,
to announce key findings of the
research project that is fully docu-
mented in a separate report of the same
title (see Project Report ordering
information at back).
Introduction
Biodegradation is believed to be the
most important degradative mechanism
for organic compounds in soil and is
utilized in soil treatment systems for the
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transformation of hazardous organic
chemicals into innocuous products. The
primary goal of biodegradation testing is
to obtain an overall estimate of the rate
at which a compound will biodegrade in
a soil environment. For quantitative
assessment of the rate of biodegradation
of an individual constituent in a soil
system, it is necessary to measure: (1)
changes in parent compound concentra-
tion with time, (2) loss of chemical due
to volatilization, and (3) chemical lossdue
to abiotic mechanism. In addition to the
degradation of hazardous constituents,
the immobilization (related to partitioning
into solid, liquid, and gaseous phases)
and the transformation of parent com-
pounds to intermediate products within
a soil system represent additional infor-
mation requirements for assessing the
potential for treatment of hazardous
constituents in soil.
The information generated in this
study was input into a comprehensive
Soil Transport and Fate Data Base that
has been established to address the
behavior of hazardous substances in soil
systems. Specific quantitative informa-
tion concerning persistence and/or
partitioning for 56 substances was
developed to provide EPA with an infor-
mation base for use in making decisions
concerning the treatability of the tested
chemicals in soil.
Specific objectives of this research
project were to:
1. Determine degradation kinetic
information corrected for
volatilization.
2. Determine the extent of chemical
incorporation into soil organic
material, and the biological and
chemical characterization of trans-
formation products.
3. Determine the contribution of.
abiotic loss to "apparent loss
rates."
4. Determine partition coefficients
among oil, water, air, and soil
phases.
5. Input the data generated for deg-
radation rates and partition coef-
ficients for a subset of the sub-
stance evaluated into the RITZ and
VIP mathematical models to eval-
uate the potential terrestrial trans-
port and fate of the substances in
soil systems.
Research Approach
Substances evaluated—Four catego-
ries of 56 substances were evaluated: (1)
polynuclear aromatic hydrocarbons
(PAHs), (2) pesticides, (3) chlorinated
hydrocarbons, and (4) miscellaneous
substances.
All chemicals except toxaphene and
tetraalkyllead (TAL) were purchased
commercially, analytical grade. The
toxaphene sample was collected from a
soil site where spent toxaphene cattle
dipping solution had been disposed. The
TAL sample was provided by Standard
Oil of California, and consisted of tetraal-
kyllead (61.5%), ethylene dibromide
(17.9%), and ethyfene dichloride (18.8%).
Soils evaluated—Two soils were used
in this study, a Kidman fine sandy loam
(Haplustoll, Utah) and a McLaurin sandy
loam soil (Paleudult, Mississippi). Neither
soil had received application of any
fertilizer or agricultural chemical in the
last five years. Soil microorganism
counts were typical for a soil with an
active microbial population.
Determination of degradation rates in
soil—Degradation describes the chemi-
cal and/or biological conversion of a
parent compound to its various interme-
diates and/or to inorganic end products
such as carbon dioxide, water, nitrogen,
phosphorous, sulfur, etc. In this study,
the rate of degradation was experimen-
tally determined by measuring the
difference between the amount of com-
pound initially added to a soil and that
which was recovered after specified time
intervals. Biological and chemical deg-
radation components were differentiated
using control soil samples treated with
HgCU. This operational determination of
degradation, however, did not distin-
guish between complete degradation and
transformation into intermediate
products.
Two experimental approaches were
used to measure degradation rates for
the chemicals evaluated in the study. In
the first approach the observed loss of
a compound due to volatilization was not
distinguished from losses attributed to
degradation rates. In the second
approach, degradation rates were cor-
rected for volatilization. The later
approach involved independent meas-
urement of losses due to volatilization
thus allowing a corrected degradation
rate for volatile chemicals to be
determined.
Partition Coefficient Determinations—
Partition coefficients between aqueous
and soil (Kd) oil (K0), and air (Kh) phases
were estimated based on structure-
activity relationships using the following
methods.
The partition coefficient of a chemical
between soil and water (Kd) is given by:
- Cs/Cw
(D
where Kd is the soil/water partition
coefficient (unitless if Cs and Cw are in
the same units), Cs is the concentration
of chemical in the soil phase, and Cw is
the concentration of chemical in the
aqueous phase.
Kd values for a soil can be estimated
from Koc values if the organic fraction
of the soil, f0c, is known and if it is
assumed that hydrophobic interactions
dominate the partitioning process:
Kd - Kocfo
(2)
where Koc is the organic carbon normal-
ized soil/water partiion coefficient.
By assuming that partitioning between
water and the organic fraction of soil is
similar to partitioning between octanol
and water, several correlation equations
have been developed which relate Koc to
octanol/water partition coefficients
(Kow). The correlation equation used to
calculate Koc for this project was:
log Koc- 1.0 log Kow -0.21
(3)
Experimental values of log Kow obtained
from the literature were used when
available. Log Kow values, estimated
using the fragment approach of Hansch
and Leo, were used when experimental
values were not available.
The second approach employed for the
estimation of log Koc was based on
molecular connectivity indexes (MCls).
MCls are topological parameters that
describe the degree of bonding or con-
nectedness of the nonhydrogen atoms in
a molecule. First-order MCls (1x), calcu-
lated from the molecular structure of a
compound, have been shown to be highly
correlated with soil/water partition
coefficients.
First order MCls were calculated using
a computer program written in Fortran
for an Apple Macintosh computer. The
KOC values were calculated from the first
order MCI using the regression equation:
log Koc = (0.53) 1x + 0.54 (4)
The resultant Koc values were used
along with percent organic carbon values
to calculate Kd values of the Kidman and
McLaurin soils using equation 2.
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The pattern coefficient of a chemical
between water and oil (Kd) is given by:
— Co/Cw
(5)
where K0 is the oil/water partition
coefficient (unitless if C0 and Cw are in
the same units), C0 is the concentration
of chemical in the oil phase, and Cw is
the concentration of chemical in the
water phase.
Ko values were estimated using a
correlation expression between K0 and
Kow and are presented bjlow:
log K0= 1.12 log Kow-0.324 (6)
The partition coefficient of a chamical
between air and water (Kh) can be written
as:
Kh - Ca/Cw
(7)
where Kh is the air/water partition
coefficient, Ca is the concentration of
chemical in the air phase, and Cw is the
concentration of chemical in the aqueous
phase.
Kh can also be expressed as a dimen-
sionless Henry's Lav*/ constant H/RT.
Values of H can be calculated from the
ratio of vapor pressure of a chemical to
aqueous solubility if it is assumed that
the liquid phase activity coefficients are
constant up to the solubility I'mit. Uring
experiment?! values for vapor pressure
(Pv) and aqueous solubility (S) obtained
from the literature, Kh was calculated
using the following expressions:
Kh = H/RT = (PV/S)/RT
(8)
where Pv is the vapor pressure (torr), S
is aqueous solubility (moles/liter), R is
the gas constant (62.3 liter torr/atm K)
and T is temperature (25°C, 298°K).
If literature values of Pv or S were
unavailable for a particular compound
but boiling point and melting point values
were available, Pv values were estimated
using the following expression:
In P, = - (4.4 + In TB)
[1 . 803(Ia _ 1)]_ 0.803 In ^ O)
where Pv is in torr and TB, TM and T are
the boiling point, melting point and an
environmental temperature (°K),
respectively.
Mathematical Model for Soil-Waste
Processes—The values developed for
degradation and partitioning in the
treatability studies for eight pesticides
were used as input for the RITZ and VIP
mathematical models. The Vadose Zone
Interactive Processes (VIP) model is an
enhanced version of the Regulatory and
Investigative Treatment Zone Model
(RITZ). The RITZ model was developed by
the EPA, Robert S. Kerr Environmental
Research Laboratory, for quantitatively
integrating the processes related to
degradation and transport of organic
constituents in the unsaturated zone of
a soil system. The «/IP model was
developed at Utah State University as
part of a previous EPA-funded study for
use in evaluation of site-specific treat-
ment potential for specific waste-soil
mixtures. The major differences between
the RITZ and VIP models are the numer-
ical solution algorithms used and the
option to use nonequilibrium kinetics in
VIP.
Transformation Studies—Transforma-
tion studies using radiolat/eled 7,12-
dimethylbenzanthracene (DMBA) were
performed with the McLaurin sandy loam
soil at low pH and the same soil adjusted
to neutral pH. The distribution cf 14C02
between evolved CO2, soil extracts, and
soil residue components was measured
to construct a mass balance for DMBA.
Mutagenicity of DMBA and metabolite
fractions were measured with the Ames
mutagenicity assay. Mutagenic potential
of each test smaple was expressed as
the mutagenic ratio (MR), i.e., ratio of
number of colonies in the presence of
a test sample to the number of colonies
on a control growth plate in the absence
of the test sample.
Results and Discussion
Degradation of PAH Constituents—
Resultsforthe Kidman sandy loam (Table
1) generally indicated that PAH persist-
ence increased with increasing molec-
ular weight or compound ring number.
The degradation of two-ring PAH com-
pounds, naphthalene and 1 methyl-
naphthalene, was extensive. Half lives
for these PAH compounds were approx-
imately two days. Comparative half lives
for the degradation of three-ring PAHs,
anthracene and phenanthrene, were 16
and 134 days respectively. Extensive
degradation of these two- and three-ring
PAH compounds is not unexpected since
these compounds can be utilized as a sole
source of carbon and energy for soil
microorganisms. The four-, five-, and six-
ring PAH compounds were somewhat
recalcitrant, exhibiting half lives of
greater than 200 days. DMBA, however,
was extensively degraded with a half-life
of 20 days.
It has been demonstrated that natural
soil microorganisms can degrade PAHs
by co-metabolic processes. The relative
stability of non-substituted high molec-
ular weight PAH compounds in this study
suggests that the resident microbial
distribution in the soils used may not
have included organisms capable of
degrading these compounds or a suitable
substrate was not present to stimulate
co-metabolic decomposition.
These results are consistent with
, esults of other studies using complex
wastes. However, higher molecular
weight PAH compounds were observed
in this study to be more resistant to
degradation when present as pure
compounds in soil than when present at
the same concentrations in the same soil
in complex waste mixtures.
Degradation of Pesticides—Toxaphene
waste residue exhibited no measurable
degradation after 150 days of incubation
at an initial soil concentration of 20 mg/
kg. The major mechanism for the deg-
radation of toxaphene in soils occurs by
reductive dechlorination. Fresh manure
was applied to the soil waste mixture (2
percent manure, dry weight basis) to
lower redox potential of the soil. Appli-
cation of manure was not effective in
stimulating degradation of toxaphene
residue after the same period of incu-
bation. Tcxaphene would be classified as
persistent in these soils.
Degradation information for pesticides
obtained in laboratory treatability studies
using the Kidman soil is presented in
Table 2. Microbiological degradation of
chlorinated pesticides has been reported
to follow first-order kinetics. The first-
order fit of data generated in this study
for many of the chlorinated pesticides
was not as good as would be expected
if the apparent loss truly followed first-
order kinetics. Degradation of organo-
phosphorus pesticides could not be
clearly characterized using a first-order
reaction kinetic model. Use of first-order
kinetics overestimated half-lives for
these pesticides.
Chlorinated Hydrocarbons and Ani-
line—Volatilization corrected degrada-
tion rates were determined for the six
most volatile chlorinated hydrocarbons in
the McLaurin soil (Table 3). Volatilization,
as measured by cumulative mass of
compound collected on Tenax over the
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course of the experiments, was a signif-
icant loss mechanism for all compounds
studied, ranging from 17 percent for
1,1,2,2-Tetrachloroethane, to over 76
percent for 1,1,2-Trichloroethane.
Partitior, coefficients—SAR-derived
partition coefficients for both experimen-
tal soils for chemicals in the four classes
evaluated are summarized in Tables 4-
6. As expected, PAH and pesticides
compound exhibited high K0 and Kd
values, while the volatile class of com-
pounds showed high Kh values. Partition
coefficients estimated using SARs were
in good agreement with literature coef-
ficient values for the compounds
addressed.
Model applications—The RITZ and VIP
models were used to simulate the
behavior of eight pesticides in Kidman
soil at a time period beyond the laboratory
determined half-life. The organophos-
phorus pesticides were predicted to
degrade significantly in 91 days (96.2
percent for disulfoton to 78.8 percent for
parathion). Approximately 70 percent of
the applied chlorinated pesticides were
predicted to degrade in this time period.
When degradation was eliminated as
an input parameter to the models,
treatment was limited to the sorptive
capacity of the soil for each pesticide.
Under these test conditions, transport
through volatilization or leaching from
the zone of incorporation (ZOI) was not
predicted by the models with the excep-
tion of toxaphene. Detectable concentra-
tions of toxaphene were predicted to be
both volatilized and leached from the
zone of incorporation in 91 days.
14C DMBA results—Parent 14C DMBA
was extensively biodegraded with a half-
7able 1.
Volatilization Corrected Degradation Kinetic Information for PAH Compounds Applied to Kidman Sandy Loam at -0.33 Bar Soil
Moisture
95% Confidence Interval
Lower Limit
Compound
Naphthalene
1 -Methylnaphthalene
Anthracene
Phenanthrene
Fluoranthene
Pyrene
Chrysene
Benz(a)anthra cene
7, 12-Dimethylbenz(a)
anthracene
Benzo(b)fluoranthene
Benzofajpyrene
Dibenzfa, h)anthracene
Dibenzo(a,i)pyrene
lndeno(1 ,2,3-cdjpyrene
n
12
J2
15
12
15
15
15
15
12
15
15
15
15
15
Co
fmg/kgl
101
102
210
902
883
686
100
107
18
39
33
12
11
8
k
(day-')
-0.3370
-0.4150
-0.0052
-0.0447
-0.0018
-0.0027
-0.0019
-0.0026
-0.0339
-0.0024
-0.0022
-0.0019
-0.0019
-0.0024
fl/2
(days)
2.1
1.7
134
16
377
260
371
261
20
294
309
361
371
288
r*
0.883
0.922
0.829
0.952
0.724
0.708
0.804
0.855
0.944
0.830
0.769
0.726
0.746
0.793
k
(day-')
-0.4190
-0.4960
-0.0065
-0.0514
-0.0025
-0.0036
-0.0024
-0.0033
-0.0394
-0.0030
-0.0029
-0.0026
-0.0025
-0.0031
fl/2
(days)
1.7
1.4
106
13
277
193
289
210
18
231
239
267
277
224
Upper Limit
k
(day-')
-0.2550
-0.3350
-0.0038
-0.0380
-0.0012
-0.0017
-0.0013
-0.0020
-0.0284
-0.0018
-0.0015
-0.0013
-0.0013
-0.0017
tt/2
(days)
2.7
2.1
182
18
578
408
533
347
24
385
462
533
533
408
Table 2. Apparent Loss Kinetic Information for Pesticides from Kidman Soil
95% Confidence Interval
Lower Limit
Pesticide
Pentachloronitrobenzene
Disulfoton
Methylparathion
Phorate
Parathion
Endosulfan
Aldrin
Famphur
Heptachlor
DDT
Linda ne
Pronamide
Dinoseb
Aldicarb
Warfarin
n
18
18
18
17
18
18
18
22
18
18
15
17
17
22
22
C0
(mg/kg)
0.300
1.56
1.04
1.42
1.45
0.580
0.429
82.7
0.588
0.574
0.394
85.3
103.1
99.1
117.8
k
(day')
-0.0398
-0.036
-0.025
-0.022
-0.017
-0.016
-0.013
-0.013
-0.012
-0.015
-0.0113
-0.0072
-0.0067
-0.0018
a
fvz
(days)
17
19
28
32
41
43
53
53
58
60
61
96
103
385
--
r2
0.925
0.589
0.472
0.435
0.690
0.854
0.889
0.860
0.908
0.524
0.384
0.876
0.890
0.435
0.520
k
(day-')
-0.046
-0.052
-0.039
-0.036
-0.023
-0.02
-0.016
-0.015
-0.014
-0.0173
-0.0199
-0.0086
-O.008
-0.0027
-~
fl/2
(days)
15
13
18
19
30
35
43
46
50
40
35
81
87
257
--
Upper Limit
k
(day'')
-0.034
-0.02
-0.01 1
-0.0082
-0.011
-0.013
-0.011
-0.01
-0.010
-0.0057
-0.0027
-0:0057
-0.0054
-0.0008
~-
fl/2
(days)
21
35
63
85
63
53
63
69
70
122
257
122
128
845
-~
"Slope (k) of first order regression line is not significantly different from zero, no degradation observed.
4
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Table 3. Volatilization Corrected Degradation Kinetic Information for Chlorinated Compounds Applied to McLaurin Sandy Loam at -0.33
BAR Coil Moisture Content
95% Confidence Interval
Lower Limit
Compound
n
Co
(mg/kg)
k
(day-1)
t-,,2
(days)
r2
k
(day-1)
fl/2
(days)
Upper Limit
k ti/z
(day'1) (days)
Degradation Data Corrected for Volatilization, Unpoisoned Soil
1 , 1 -Dichloroethylene
1 ,1 ,1 - Trichloroethane
7,7,2- Trichloroethane
1,1 ,2,2- Tetrachloroethane
4
4
6
6
156.0
155.2
155
147
-16.34
- 9.60
-30.55
-53.42
0.04
0.07
0.02
0.01
0.788
0.936
0.599
0.588
-42.14
-17.21
-65.28
-115.54
0.02
0.04
0.01
0.01
-1.97 0.35
Degradation Data Corrected for Volatilization, HgCI Poisoned Soil
Chloromethylmethyl ether
7,7 ,2 -Trichloroethane
1 ,2-Dibromo-3-chloro-
propane
5
5
6
123.6
155
144.9
-55.68
-63.48
-70.34
0.01
0.02
0.01
0.558
0.536
0.516
-146.69
-172.10
-164.05
0.00
0.00
0.00
-
'Slope (k) of first order regression line is positive, no degradation observed.
Table 4. Calculated Soil/Water (Ka), Oil/Water
Coefficients for PAH Compounds
(K0), and Air/Water (Kh) Partition
Compound
Acenaphthylene
Benz(a)anthracene
Benzo(a)pyrene
Chrysene
Dibenzo(a,h)anthracene
ldeno(1,2,3-cd)pyrene
3-Methylcholanthrene
Fluoranthene
1 -Methylnaphthalene
Naphthalene
Phenanthrene
Pyrene
Benzo(b)fluoramhene
7,12-Dimethylbenz(ajanthracene
Anthracene
LogKa
(McLaurin)
1.72
3.24
3.67
3.24
3.60
5.27
4.73
2.97
1.52
1.01
2.11
2.96
4.19
3.61
2.10
LogKa
(Kidman)
1.38
2.90
3.33
2.90
3.26
4.93
4.38
2.62
1.18
0.67
1.76
2.61
3.86
3.27
1.75
LogK0
4.23
5.95
6.43
5.95
6.35
8.24
7.63
5.64
4.00
3.42
4.66
5.63
7.02
6.36
4.65
LogKh
-7.22
-5.36
-2.75
-2.4!
-5.52
-7.62
—
-3.60
—
-1.97
-2.30
-4.27
-2.91
—
-1.59
life of 17 days. Half-life was determined
from the decrease of the DMBA 14C
fraction over time, which was corrected
for abiotic loss and volatilization. These
results are consistent with results
obtained for a non-radiolabeled DMBA
degradation study, which gave biodeg-
radation half-lives of lives of 20 to 28
days. Abiotic loss of 14C DMBA from soil
samples poisoned by 2% HgClj was
statistically not significant (p=0.05). 14C
DMBA volatilization was not detected
during the 28-day soil incubation period.
The decrease in the parent PAH 14C
was accompanied by an increase in
metabolite 14C fraction (Table 7). Incor-
poration of 14C DMBA into a nonextrac-
table soil residue 14C increased from 12
to 17%, however, the increase was not
statistically significant (p=0.05). Evolu-
tion of 14COz was not detected during the
28 days of incubation. These results do
not demonstrate that the parent com-
pound was not metabolized to C02 since
14C DMBA used was radiolabeled only
at the 12 position carbon. In order to
detect 14C02, the benzene ring which
contained the carbon-12 was required to
be mineralized to COz.
Several metabolic intermediate prod-
ducts of DMBA biodegradation were
characterized by GC/MS analysis. These
included 10-hydroxy-, 4-hydroxy-, and 5-
hydroxy-DMBA, respectively. HPLC ret-
ention time of these metabolites were
identical with those given by reference
standards. HPLC elution profile from
incubation of 14C DMBA revealed a
complex mixture of metabolic products.
The elution profile further showed
formation of highly polar metabolic
products eluting prior to HPLC retention
time of DMBA.
Results from Ames assay testing for
DMBA metabolites indicated that the
highly polar metabolic fraction was
mutagenically inactive suggesting that
these metabolites may be the detoxified
conjugation products of soil microbial
enzymes. Moderate and nonpolar metab-
olite fractions induced a positive
response. The mutagenic potential of
these metabolite fractions, however,
decreased with an increase in soil
incubation time. This detoxication poten-
tial of DMBA may be important for
engineering management and control of
hazardous wastes containing this PAH
compound since toxicity reduction as a
function of incubation time in soil can
be used to assess the success of
treatment.
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Table 5. Calculated Soil/Water (Ka), Oil/Water (K0). and
Coefficients for 22 Pesticides
LogKa
Compound (McLaurin)
Aldrin 0.65
Cacodylic A cid -2.3 1
Chlordane, technical 0.44
DDT 1.14
Dieldrin 0.56
Dinoseb
Disulfoton -2.31
Endosulfan 1.21
Heptachlor 1.55
Alpha Lindane 1.46
Methyl parathion 0.65
Parathion 1.06
Phorate 0.58
Toxaphene 0.96
Warfarin 0.19
Aldicarb -1.61
LogKa
(Kidman)
0.31
-2.65
0.10
0.79
0.22
~™
-2.65
0.56
1.21
1.12
0.31
0.72
0.24
0.62
-0.15
-1.95
Air/Water (Kh)
LogK0
0.62
-0.32
2.79
3.57
2.92
2.25
-0.32
3.65
4.04
3.94
3.02
3.48
2.94
3.37
2.49
0.46
Partition
LogKh
-1.93
—
-2.40
-2.44
-4.69
-4.13
-2.44
-0.97
-4.47
-5.56
-4.04
-3.40
-5.13
__
-6.59
Table 6. Calculated Soil/Water (KA). Oil/Water (K0J. and Air/Water (Kh) Partition
Coefficients for Chlorinated Hydrocarbons and Miscellaneous Compounds
LogKa
Compound (McLaurin)
Chlorinated Hydrocarbons
Bis-fchloromethy/lether -2.68
Chloromethylmethyl ether -1.41
1 .2 -Dibromo-3 -chloropropane
Dichlorodifluoromethane -0. 1 7
1.1 -Dich/oroethy/ene
1 ,1 ,1 -Trichloroethane 0.13
1,1,2,2-Tetrachloroethane 2.63
1 .1 ,2-Trichloroethane -0.16
1 ,2,2-Trichlorotrifluoroethane -0. 66
Hexachlorocyclopentadiene 2.68
4,4 -Methylene-bis-
(2-chloroaniline) 0.96
1 ,2,4-Trichlorobenzene 1.63
Miscellaneous Compounds
Aniline 1.44
Mitomycin C 8.95
Pyridine 1.04
Tetraethyllead 2.28
Uracil mustard 4.82
LogKt
(Kidman)
-3.02
-1.75
-0.51
0.47
2.29
-0.50
-1.01
2.34
0.62
1.29
1.09
8.61
0.70
1.94
4.47
LogKo
-0.75
0.69
2.09
2.14
5.26
2.10
1.53
5.31
3.37
4.13
2.34
2.34
2.13
2.79
4.13
LogK*
—
—
2.01
-0.79
-1.81
-1.51
—
-1.37
—
-0.77
—
—
—
—
—
Conclusions
The importance of volatilization and
abiotic-loss processes in influencing
"apparent loss rates" of substances from
soil systems depends upon the class of
substances. These processes are insig-
nificant for the majority of PAH com-
pounds. Biodegradation appears to be the
major process for loss of PAHs from soil
systems. Abiotic loss may be an impor-
tant process for certain pesticides.
Volatilization appears to be the major
process influencing loss rates of volatile
substances from soil systems.
Transformation products of mutagenic
parent substances may exhibit muta-
genic characteristics, but may decrease
in mutagenic potential with incubation
time in soil. A decrease in the concen-
tration of parent substance in a soil
extract solution that is not accompanied
by an increase in carbon dioxide evolu-
tion may not indicate irreversible soil
incorporation of applied waste. Rather,
intermediate biochemical transformation
products may occur that exhibit changing
characteristics with time of incubation in
the soil.
Mercuric chloride is effective for
reducing soil bacteria and fungi to levels
at least as low as 1 0 organisms per gram
of soil (dry-weight basis). However, the
use of HgCI2 may greatly affect the
recovery of certain compounds from soil.
The use of HgCI2 sterile controls for
biodegradation studies should be further
examined.
It is possible to develop transport
information for mathematical models by
calculating partition coefficients based
on structure-activity relationships for
substances that are difficult to evaluate
experimentally.
Under environmental and loading rate
conditions representative of well
designed and well managed soil treat-
ment systems, very little leaching or air
emissions of either pesticides or PAH
compounds was predicted by the RITZ or
VIP models using soil fate and transport
input data generated in laboratory exper-
iments or in literature citations.
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Table 7. Transformations ofC4C) 7,12-Dimethylbeni(a)anthracene by McLaurin Sandy Loam
" Soif
14C appearing in each fraction (%)
Soil Extract
Time
(days)
0
14
28
7,12-Dimethylbenz(a)-
anthracene
(parent compound)
62 (69)
26
20 (60)
Metabolites
4 (6)
43
53 (1 1)
Soil
Residue
12 (13)
16
17 (16)
CO2
0(0)
0
0(0)
Total
78 (88)
85
90 (87)
'Poisoned (control) data in parentheses.
Ronald C. Sims. W. J. Doucette. J. E. McLean, W. J. Grenney. andR. R, Dupont
are with Utah State University, Logan, UT 84322.
John E. Matthews is the EPA Project Officer (see below).
The complete report, entitled "Treatment of Potential for 56 EPA Listed
Hazardous Chemicals in Soil," (Order No. PB 88-174 446/AS; Cost: $19.95,
subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Roberts. Kerr Environmental Research Laboratory
U.S. Environmental Protection Agency
P.O. Box 1198
Ada, OK 74820
t n-nicDuiicuruoiuTiunnccu-E.
-------
United States Center for Environmental Research BULK RATE
Environmental Protection Information POSTAGE & FEES PAII
Agency Cincinnati OH 45268
PERMIT No G-35
Official Business
Penalty for Private Use $300
EPA/600/S6-88/001
0000329 PS
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