Bound 14C residues were higher in oats grown in the sandy
soil than in loam-grown oats. The oxygen analogue metabo-
lites of the organophosphorus insecticides were most abun-
dant in the sandy soil and in oats grown therein. Data illus-
trate the importance of chemical structure, water solubility,
and soil type in predicting the comparative environmental
behavior of pesticides.

Chemical Interactions

Effects of Parathion Residues in Soil on the Fate of
[14C] Parathion

Pretreatment of cranberry soils with parathion or p-nitrophenol
considerably increased the degradation of [ring-14C] parathion.
This is indicated by the increase in the evolution of 14CO2, as
shown in Figure 2. The effects of soil pretreatment were in
particular evident one day after soil treatment with [14C]par-
athion. While in controls only 2% of the applied radiocarbon
had been released as 14COp, this figure amounted to 34%
and 39% with soils pretreated with p-nitrophenol or para-
thion, respectively.

Effects of Selected Fungicides on the Fate of
[Ring-14C]Parathion in Cranberry Soils

As shown in Table Ill, the degradation of [14C] parathion was
considerably inhibited by captafol, since 66 % of the applied
insecticide was still present in these soils, as opposed to only
3% in controls. The decreased metabolism of the insecticide
is also indicated by a significant reduction in bound radio-
carbon. Captafol apparently inhibited these soil microorgan-
isms which are usually responsible for the degradation of the
insecticide. The effects of captafol on the biodegradation of
[14C]parathion were similar to those observed with auto-
claved soils.

Maneb also inhibited 14CO. evolution from [14C]parathion
but not the total degradation of the insecticide. As shown in
Table Ill, only 8% of the applied insecticide was recovered;
yet considerably more benzene-soluble radiocarbon (23%)
was still present. Thin-layer chromatography of the benzene
extraction phase revealed the presence of p-amino[14C]phenol

2
°

1 r T T T T
Perathion _

ano

at
Wp Cas Nitrophenol
Treated Soil

g 8
ei -2
vo

z
cy

ca

Cumulative “CO, Evolution
‘in % of Applied 'C-(Ring)-Parathion

rr a
q Days | Days after '*C-Insecticide Treatment

Parathion or ‘“C-Parathion
p-Nitrophenol Applied

Figure 2. Effect of parathion or p-nitrophenol in soil on the
evolution of **CO, from soil-applied [ring-"*C}
parathion. Results are means of duplicate tests and
represent accumulated ‘CO, evolution.

in addition to [14C]parathion. As demonstrated by Katan
and Lichtenstein (1977), binding of parathion residues to
soils occurs after the insecticide has been reduced to amino
compounds. Thus, in the presence of maneb, 66% of the
soil-applied radiocarbon was unextractable as opposed to
38% with control soils. It appears, therefore, that maneb did
not affect soil microorganisms which are responsible for the
reduction of parathion in cranberry soils.

Benomyl affected [14C]parathion degradation, although toa
lesser extent than did captafol and maneb. Thus, in benomyl-
treated soils the amount of 14CO2 evolved was only 18% of
the applied radiocarbon. As with maneb, the presence of
benomy!l in the soil resulted in recoveries of larger amounts
of benzene-soluble radiocarbon and in increased binding of
14C-labeled compounds.

The fungicide PCNB did not affect the fate of [14C] parathion
incranberry soils. This fungicide is not harmful to bacteria; in
some cases, it increases their number in soils.

Effects of Selected Herbicides on the Fate of
[14C]Parathion in Cranberry Soils

Results obtained in experiments with 2,4-D and [14C]para-
thion showed that the persistence of parathion in cranberry
soils was increased in the presence of the herbicide, 2,4-D.
Thus, after three weeks of incubation, only 2.09 + 0.31%
of the applied [14C]parathion could be recovered from control
soils, but 12.2 + 2.3% of the applied [14C]parathion was
recovered from 2,4-D-treated soils. This suggests that 2,4-D
may have inhibited the reduction of {14C]parathion by affect-
ing the activity of nitroreductase-producing microorganisms.

Effects of Fertilizers on the Fate of [14C]Parathion in
Cranberry Soils

Some nitrogen fertilizers can indeed inhibit the degradation
of [14C]parathion in cranberry soils. Thus, application of
(NH4)2SO, to [14C]parathion-treated cranberry soils inhibited
the degradation of the insecticide to 14COz, since only 8%
of the applied radiocarbon evolved as 14COz during the
3-week incubation period. In controls, however, this figure
amounted to 46%. Potassium nitrate also reduced the forma-
tion of 14CO, but not to the extent observed with (NH4)2SO4.
Addition of NH4NO3 or urea to [14C]parathion-treated soils
had no apparent effect.

Results obtained after extraction and analyses of fertilizer-
treated soils and vapor traps are summarized in Table IV.
Although under all experimental conditions the total amounts.
of 14C recovered were similar, the distribution of 14C-labeled
compounds into benzene-soluble, water-soluble, and bound
residues was not, thus possibly indicating a drift in the path-
way of [14C]parathion degradation. The insecticide was
most persistent in soils containing (NH4)2SQq4. This is
demonstrated by a recovery of 29% of the applied radiocar-
bon in the benzene-soluble form. Analyses by TLC and auto-
radiography of this benzene extraction phase reversed the
presence of {14C]parathion, p-amino [14C]phenol, and
amino[14C]parathion. Compared to controls, some increase
in bound radiocarbon was also noticeable in the presence of
(NHq)2S04. Inhibitory effects of KNO3 on parathion metab-
olism were also evident after extraction and analyses of
soils and vapor traps (Table IV). All analytical results
obtained with fertilizers in the form of NH4NOsor urea were
similar to those observed with controls (Table IV).

5


Table VI.

Influence of Water Transpiration on the Uptake of Radiocarbon from [14C}Phorate-Treated Soil by C3 and C4

Plants@
mi of Water Transpired/g Fresh Weight of Greens
Expt. Cz Plants C4 Plants Ca/C4P
' A. patula 75.4 + 3.1 A. rosea 55.3 + 3.8
I Pats 127.0 + 12.2° Corn 62.2 +44
aT Barley 134.4 4 1.1 Sorghum 57.0 +2.0
Wheat 118.5 + 48 Millet 39.5 + 2.6
Average 114.7 51.0 2.25
Radiocarbon Recovered/g of Plant Tops, Percent of ['4C]Phorate Applied to Soil
Expt. Cy Plants C4 Plants C3/C >
1 A. patula 4.77 + 0.35 A. rosea 3.90 + 0.06
il Oats 7.59 + 0.19¢ Corn 3.14 + 0.29
Peas 653+ 1.1249
Ml Barley 10.0 + 1.20 Sorghum 4.70 + 0.06"
Wheat 7.80 + 0.62 Millet 2.93 + 0,.21¢
Average 7.34 3.67 2.00

® Results are means + SD of triplicate tests (I and Il) or averages of duplicate tests (ltl). Grown in a Plainfield sand treated with ['4C}phorate at 1
ppm (4.3 Ci, for experiments | and I) or at 0.5 ppm (2.2 4Ci, for experiment Ill). Growing conditions in experiment | were 32°C, 50%
relative humidity, in experiment i, 28 °C, 35% relative humidity, and in experiment Ill, 28 °C, 30% relative humidity.

> Ca/Cq = ratio between average milliliters of water transpired or the average 14C recovered from C, and C, plants, respectively.

© Within each block (I, II, II], data without a letter in common are significantly different (5% level, Duncan’s new multiple range test).

Table Vil. Metabolism of [C14C]Phorate in Oat (C3) and

Corn (4) Plants

14C Recovered, Percent of
U4C]Phorate Applied? (per g>)

Extraction Phase Oats (C3) Corn (C4)
Tops
Benzene 2.92 + 0.05 1.52  0.32¢
Water 3.83 + 0.08 1.27 + 0.074
Bounds 0.84 + 0.18 0.35 + 0.04!
Total 7.59 + 0.19 3.14 + 0.294
Roots
Benzene 0.09 + 0.01 0.06 + 0.01!
Water 0.12 + 0.02 0.11 £0.01
Bound 0.95 + 0.04 0.18 + 0.024
Total 1.16 + 0.06 0.35 + 0.03¢

4 Results of triplicate tests.

» Per gram of fresh weight.

© Unextractable 14C residues as determined by combustion to
14¢0,.

¢ Significant difference at the 0.1% (students t-test).

© Significant difference at the 1.0%.

f Significant difference at the 5.0%.

Ferris, |.G., and Lichtenstein, E.P. Interactions Between
Agricultural Chemicals and Soil Microflora and Their Effects
on the Degradation of {14C]Parathion in a Cranberry Soil. J.
Agr. Food Chem. 28(5):1011-1019 (1980).

Fuhremann, T.W., and Lichtenstein, E.P. Release of Soil-
bound Methyl 14C-Parathion Residues and Their Uptake by
Earthworms and Oat Plants. J. Agr. Food Chem. 26(3):605-
610 (1978).

Fuhremann, T.W., and Lichtenstein, E.P. A Comparative
Study of the Persistence, Movement, and Metabolism of Six
Carbon-14 Insecticides in Soils and Plants. J. Agr. Food
Chem. 28(2):446-452 (1980).

8

Gorder, G.W., and Lichtenstein, E.P. Degradation of parathion
in culture by microorganisms found in cranberry bogs. Can.
J. Microbiol. 26(4):475-481 (1980).

Katan, J., Fuhremann, T.W., and Lichtenstein, E.P. Binding
of [14C]Parathion in Soil: A Reassessment of Pesticide Per-
sistence. Science 193(4256):89 1-894 (1976).

Katan, J., and Lichtenstein, E.P. Mechanism of Production
of Soil Bound Residues of 14C-Parathion by Microorganisms.
J. Agr. Food Chem. 25(6):1404-1408 (1977).

Koeppe, M.K., and Lichtenstein, E.P. Effects of percolating
water, fungicides and herbicides on the movement and
metabolism of soil applied 14C-carbofuran in an agro-eco-
system. From Masters Thesis. Available at University of
Wisconsin Library. Submitted for publication (1980).

Koeppe, M.E., and Lichtenstein, E.P. Binding and 14CO.-
evolution from 14C-carbofuran and 14C-fonofos in soils.
From Masters Thesis. Available at University of Wisconsin
Library. Submitted for publication (1981).

Kunstman, J.L., and Lichtenstein, E.P. Effects of nutrient
deficiencies in corns on the in vivo and in vitro metabolism of
14C-diazinon. J. Agr. Food Chem. 27(4):770-774 (1979).

Kunstman, J.L., and Lichtenstein, E.P. Effects of soil tem-
peratures and photoperiod on translocation of insecticides
into plants. From Ph.D. Thesis. Available at University of
Wisconsin Library and also on microfilm, Ann Arbor, Michi-
gan. Submitted for publication (1981).

Kunstman, J.L., and Lichtenstein, E.P. Effects of plant
pathogens on the uptake, translocation and metabolism of
14C-carbofuran in corn plants. From Ph.D. Thesis. Available
at University of Wisconsin Library and also on microfilm,
Ann Arbor, Michigan. Submitted for publication (1981).

Liang, T.T., and Lichtenstein, E.P. Effects of Cover Crops on
the Movement and Fate of Soil-Applied (14C)-Fonofos in a
Soil-Plant-Water Microcosm. J. Econ. Entomol. 73:204-210
(1980).



Table Il. Summary of Uptake, Translocation, Distribution, and Metabolism of Six 14C Insecticides in Oat Plants Grown in

Insecticide-Treated Soils

Radiocarbon Recovered in Percent of '4C Insecticides Applied to Soils From

Loam Soil? Sandy Soil
Extraction Phases® Soil Oat Roots Oat Tops Soil Oat Roots Oat Tops
p.p-DDT
Extractable LSC 95.4 + 0.3 0.40.1 0.2 +02 83.3 + 3.0 4.2207 0.2 + 0.0
TLC
DDT 90.44 0.24 NAS 80.44 4.28 NA
DDE 3.44 0.0 NA 2.28 0.24 NA
Othert 17 0.0 NA 1.4 0.2 NA
Bounds —- LSC 2.8 40.4 0.0 + 0.0 0.1 + 0.0 0.7 +03 0.1 +0.0 0.1 + 0.0
Lindane
Extractable LSC 62.1 41.5 0.4 + 0.2 0.4 + 0.0 45.6 + 3.6 2441.0 1.8 20.2
TLC
Lindane 53.5¢ 0.54 0.34 33.86 2.54 1.24
Unknown" 68 0.0 0.0 5.5 0.4 0.0
Other 17 0.0 0.0 2.0 0.3 0.0
Bound Lsc 4641.2 0.1 + 0.0 0.1 0.0 1340.2 1.0 £0.2 0.2 + 0.0
Fonofos
Extractable LSC 49.4 + 4.0 0.4 + 0.0 2.5 40.1 37.9 + 4.2 1.9 + 0.4 3.2 40.2
TLC
Fonofos 42.84 0.16 0.0 29.48 0.84 0.18
-oxon 0.54 0.0 0.0 1.14 0.18 0.24
Other 5.4 0.0 0.4 1.7 0.2 O14
Bound usc 15.6 + 0.3 1.2401 0.2 + 0.0 9.3 20.8 4.7 +08 0.4 + 0.0
Parathion
Extractable LSC 43.2 £ 2.2 0.2 + 0.0 0.4 + 0.0 55.3 44.3 2.5 +0.1 2.6404
TLC
Parathion 40.08 0.14 0.18 50.84 11d 0.84
-oxon 0.54 0.0 0.0 2.48 0.14 0.64
Other 1.6 0.0 0.0 0.4 0.4 0.1
Bound Lsc 29.1 + 1.0 0.7 £0.1 0.3 + 0.0 6.0 + 1.7 5.3 + 0.7 1.2401
Phorate
Extractable LSC 56.4 + 4.0 0.20.1 6.3 40.7 22.2 $1.2 0.8 +0.1 26.7 + 1.6
TLC
phorate 2.4 0.0 0.0 3.7 0.0 0.0
-sulfoxide 24.08 0.16 0.49 12.16 0.28 7.34
-sulfone 26.18 0.18 0.58 3.54 0.24 3.66
Other 1.2 0.0 0.9 17 0.0 44
Bound isc 13.1 20.8 0.3 +0.1 0.8 +0.1 4520.1 2.7 40.1 3.2404
Carbofuran
Extractable LSC 30.6 + 0.6 0.7 £0.1 51.7 +6.1 10.4 + 3.2 2.8 + 0.6 61.1 + 4.0
TLC
Carbofuran 23.54 o.1d 5.1e 5.78 0.34 7.98
3-keto- 25 0.0 1.6 0.8 0.1 2.7
3-hydroxy- 1.0 0.18 24.94 1.64 0.34 27.16
Other 18 0.0 8.7 0.9 0.3 8.4
Bound usc 10.4 + 1.0 1.0 + 0.2 3.0 + 0.2 0.8 + 0.1 2.80.1 2.5 40.1

4 Analyses of the extraction phases were conducted by LSC and TLC. For metabolism studies, compounds were separated by TLC, eluted,
and quantitated by LSC.

> Applied 4 ppm (2.2 - 5.5 wCi) of 14C insecticides to 550 g of silt loam soil. Results are means + SO for three replicates.

© Applied 2 ppm (2.8 - 7.0 yCi) of 14C insecticides to 700 g of Plainfield sand. Results are means + SD for three replicates.

4\dentity confirmed by GLC.

© Not analyzed.

Compounds included in ‘‘other’’ are described in text.

© Unextracted radiocarbon remaining in soils or plant pulp determined by combustion to 14CO2.

+ Unknown; suspected to be y-PCCH based on report by Yule et a/. (1967). No authentic reference compound available for comparison.

4


Table Ill.

Effects of Fungicides® on the Fate of [Ring14C]Parathion¢ in Cranberry Soil>

14C Recovered in Percent of Applied [Ring-14C}Parathion in Cranberry Soil Plus:

Difolatan Manzate Benlate Terraclor
None (Control) (Captatol) {Maneb) (Benomy!) (PCNB)
Soil
Extraction Phases
Benzene'4C 7.30 + 2.03 74.8 + 10.2f 22.9 +21! 16.7 + 1.789 4.93 + 0.25
Parathion? 2.83 + 1.01 65.6 + 14.0 8.00 + 3.6 4.12 + 0.88 1.40 + 0.17
Water 0.69 + 0.55 1.02 + 0.02 0.67 + 0.19 0.47 + 0.05 0.56 + 0.04
Bound® 37.5 £2.1 6.63 + 2.59 65.6 + 5.79 56.0 + 5.99 39.1 + 1.04
Vapor Traps
Polyurethane 1.45 + 0.22 2.83 + 0.460 2.78 + 0.209 1.76 + 0.208 1.61 40.14
KOH 14 44.5 + 3.0 7.72 £ 6.780 2.87 + 1.58 18.4 + 4.48 44.0 +£1.7
% of Control 100 7 6. 41 99
Total 91.4 £25 93.0 + 3.5 94.9 + 2.4 93.3 +18 90.2 + 0.05

® Captafol (analytical grade) and commercial formulations of Manzate, Benlate, or Terraclor were mixed with soil at 100 ppm of Al ona dry

weight basis.

> Results obtained after 3 weeks of incubation are means + SD of triplicate tests.

© Applied [ring-14C]parathion (0.34 uCi) at 8.5 yg/cm?.
4 Determined by GLC.

® Unextractable, bound 14C.

£.9 Data are signi

antly different from respective controls (none) at the 0.1% and 1%9 level (Student's t-test).

Table IV. Effects of Nitrogen Fertilizers® on the Fate of [Ring14C}Parathion in Cranberry Soils>
14C Recovered in Percent of Applied [Ring-!4C]Parathion® in Cranberry Soil Plus:
None (Control) (NH,)2504 KNO3 NH4NOg Urea
Soil
Extraction Phases
Benzene 5.47 + 0.39 28.7 + 9.4 12.1 £17 5.86 + 0.55 5.26 40.11
Water 0.37 + 0.09 0.70+ 0.28 0.65 + 0.11 0.57 + 0.05 0.50 + 0.36
Bound? 33.7 + 0.06 48.6 + 10.4 42.4 +48 31.5 +0.7 36.7 +1.3
Vapor Traps
Polyurethane 2.21 + 0.44 3.90+ 1.0 3.55 + 0.39 1,88 + 0.89 2.10 + 0.56
KOH 45.8 +1.0 7.94 + 0.83 29.5 +£0.51 48.7 £141 45.4 + 0.07
Total 87.5 +0.4 89.8 + 0.6 88.2 +1.7 88.6 +0.6 89.9 +1.6
Soil pH After:
No Incubation 5.97 + 0.02 5.34 + 0.04 5.24 + 0.03 37 + 0.03 6.06 + 0.01
3-Week Incubation 5.64 + 0.06 5.144 0.15 + 0.04 6.06 + 0.07 6.40 + 0.06

* Mixed with soils at 100 ppm of nitrogen equivalent.

> Results obtained after 3 weeks of soil incubation are averages of duplicate tests.
© [Ring-14]Parathion (0.81 Ci) was applied to the soil surface at 8 ug/cm?.

4 Unextractable, bound 14C.

Plant/Soil Interactions

In two interrelated studies in soil/plant interactions the fol-
lowing phenomena were examined: 1) effect of plant cover
on chemical transport; and 2) comparative chemical uptake
by C3 and C, plants.

1) The microcosm described above under ‘’Results and Dis-
cussion’’ was used to evaluate the effect of plants (corn or
ryegrass) on the movement and metabolism of a soil-applied
14C fonofos. Fonofos plus its metabolites were least persis-
tent with bare soils and most persistent with ryegrass (Table
V). 14C materials transported out of the terrestrial portion of
the microcosm were primarily associated with the sediment
portion of the runoff and subsequently were found in the
lake and sediments. 14C fonofos was the major constituent
in both soils and aquatic sediments with the major metabo-
lite identified as the methyl phenyl sulfone. This study em-
phasizes the considerable effect that the presence of plants
as well as type can have on chemical mobility and metabo-
lism.

6

2) As indicated above, plant type plays an important role in
the dispersal of a chemical in an ecosystem. Differences in
physiology and/or anatomy can effect uptake and transloca-
tion of materials from the surrounding medium. To evaluate
the effects of plant physiology on chemical transport, com-
parative study of water transpiration, and chemical uptake
and metabolism by C3 C4 plants was conducted. To eliminate
possible differences due to plant genera Atriplex patula (C3)
and Atriplex rosea (C4) in addition were included as test
species as well as other representatives of C3 (oats, peas,
barley, and wheat) and Cy (corn, sorghum, millet) plants. C3
plant transpired 2.5 times more water and took up twice as
much [14C] phorate residues than did C, plants (Table VI),
indicating a direct correlation between water transpiration
and 14C uptake.

Differences in the metabolism of {14C]phorate in C3 and Cy
plants are also evident when the amounts of benzene-
soluble, water-soluble and unextractable (bound) radiocar-
bon are compared (Table VII).


Lichtenstein, E.P., Fuhremann, T.W., and Schulz, J.R., J.
Agric. Food Chem. 22, 991 (1974).

Lichtenstein, E.P., Katan, J., and Anderegg, B.N. Binding of
“Persistent’’ and “‘Nonpersistent’”’ 14C-Labeled Insecticides
in an Agricultural Soil. J. Agr. Food Chem. 25(1):43-47
(1977).

Lichtenstein, E.P., Kuntsman, J.L., Fuhremann, T.W., and
Liang, T.T. Effects of Atrazine on the Toxicity, Penetration
and Metabolism of Carbofuran in Houseflies. J. Econ. En-
tomol. 72(5):785-789 (1979).

Walter-Echols, G., and Lichtenstein, E.P. Microbial reduc-
tion of phorate sulfoxide to phorate in a soil-lake mud-water
ecosystem. J. Econ. Entomol. 70(4):505-509 (1977).

Walter-Echols, G., and Lichtenstein, E.P. Effects of lake bot-
tom mud on the movement and metabolism of 14C-phorate
in a flooded soil-plant system. J. Env. Science Health 13(3):
149-168 (1978a).

Walter-Echols, G., and Lichtenstein, E.P. Movement and
metabolism of 14C-phorate in a flooded soil system. J.
Agric. Food Chem, 26(3):599-604 (1978b).

Walter-Echols, G., and Lichtenstein, E.P. Fate of 14C-phorate
in an aquatic system with E/odea plans: Metabolism, uptake
and location of residues. From Ph.D. Thesis. Available at
University of Wisconsin Library and also on microfilm, Ann
Arbor, Michigan. Submitted for publication (1981).

*USGPO: 1982 — 559-092/0497

9


Environmental Research
Laboratory
Corvallis OR 97333

EPA-600/D-82-272 August 1982

United States
Environmental Protection
Agency

Research and Development

ENVIRONMENTAL
RESEARCH BRIEF

2EC EIVED
Biological Effects and Interactions of
Pesticides in a Soil-Plant-Water Microcosm

QONML- rt rKUIbuliuN AGENCY
LIBRARY, REGION V

J.D. Gile
Environmental Research Laboratory, Corvallis OR 97333

Abstract

A soil-plant-water microcosm was used to develop a data
base for pesticide transport and metabolism and to determine
the effects of varying environmental conditions and/or com-
ponents on chemical movement in a terrestrial ecosystem.
The system was used in a comparative transport study with
lindane, fonofos, parathion, phorate, DDT, and carbofuran.
The results demonstrated the importance of chemical struc-
ture, water solubility, and soil type in predicting comparative
chemical behavior. The system was also employed in studies
of the effects of crop abundance on chemical movement and
the interactions between agricultural chemicals that can
affect chemical movement.

Studies were also conducted on the effects of plant type,
plant nutrition, soil microorganisms, chemical interactions
on pesticide transport, and metabolism. These studies em-
phasize the importance of ecosystem interactions in deter-
mining chemical transport through ecosystems and into
food chains.

introduction

A major portion of applied pesticides end up in soil. Contami-
nation of the soil with pesticides can affect plant growth,
contaminate plants and groundwater, and contaminate
animals that consume the plants and/or the water. Consider-
ation must be given to the effects of the biotic and abiotic
environment on the chemical plus its interactions with other
chemicals. The potential movement of pesticides through
the food chain was studied by evaluating the relationship
between plants, soil, and water. The study consists of re-
search in five related areas: 1) microcosm development; 2}
interaction of chemical residues; 3) binding and release of
residues in soils; 4) residue fate in flooded soils; and 5) ef-
fects of environmental factors and plant type on pesticide
uptake and metabolism. This Research Brief summarizes re-

search conducted by Prof. E. Paul Lichtenstein and students
in the Department of Entomology, University of Wisconsin,
Madison, Wisconsin. For the purposes of this summary, the
material will be presented as methods development and data
base development with regard to ecosystem interactions
and their impact on chemical movement through the food
chain. The specific papers that are addressed represent the
five related study areas. The research was supported by EPA
cooperative agreement CR-804920 and the College of Agri-
culture and Life Sciences, University of Wisconsin (Project
1387).

Results and Discussion

Methods Development

Traditionally, the transport and effects of chemicals have
been studied in isolated laboratory experiments or in field
situations. While chemical and physical studies provide key
information for use in understanding chemical behavior,
they do not account for the complexity of an ecosystem and
its attendent interactions which can moderate chemical
behavior. Conversely, because of this complexity the results
from field studies are often difficult to interpret. Therefore,
in parts of this study a model ecosystem or microcosm was
used. This approach is an intermediate step, not a complete
alternative.

The microcosm utilized in parts of this project was designed
to examine chemical movement in both terrestrial and aquatic
ecosystems. The focus in the terrestrial portion was on plant
uptake and movement through the soil column to ground-
water; in the aquatic portion emphasis was placed on chemi-
cal introduction via groundwater and subsequent partitioning
between the biotic and abiotic components of the simulated
pond (Figure 1). The dimensions of the terrestrial portion are
49 cm high, 39 cm deep, and 26 cm wide. Individual com-
ponents consist of two soil containers, each 10 cm high, 22

»> D>


Table V.

Effects of Cover Crops on the Fate and Movement of 14C-(R)-Fonofos in a Soil-Plant-Water Microcosm (Results

are Expressed as Averages of the Amounts of Radiocarbon Recovered from Duplicated Tests)

Terrestrial Soil Containing '4C-Fonofos® Plus

Fallow Com Rye Grass
Recovered From Total Sample PergWt ‘Total Sample Per g Wt Total Sample Per g Wt
14¢~ Recovered¢ in Percent of Applied to Upper Soil Layer®

Terrestrial Part 19.3 +09 0.06 31.9 £05 0.08 58.3 +0.0 0.14
Soil (S) 5.5 40.5 0.02 B84 £12 0.02 64 £15 0.02

us 24.8 40.3 64.7

Crops (C)
Leaves - 5.5 +06 0.87 1.72
Roots 67 +03 1.67 2.29
Total (C) 12.2

Total (S + C) 24.8 52.5

Runoff 1
Water (W) 2.4 40.2 0.004 1.5 £01 0.003 1.0 +01 0.002
Soil (S) 10.7 +01 0.19 48 40.5 0.21 0.3 +01 0.11
w+sit) 13.1 6.3 ° 1.3

Runoff 2
Water (W) 1.9 £0.2 0.003 0.8 +01 0,002 1.0 +01 0.002
Soil (S) 84 +03 0.18 2.9 £02 0.17 0.3 +0.0 0.04
W +S (2) 10.3 3.7 1.3

Runoff 3
Water (W) 1.0 +01 0.002 0.4 +01 0,001 0.6 £01 0.001
Soil (S) 8.4 +03 0.18 2.9 £0.2 0.17 0.3 +0.0 0.04
W + S(3) 10.3 3.7 1.3

Total (1 + 2 + 3)
Water (W) 5.3 +01 2.7 £00 2.6 +0.1
Soil (S) 26.8 +1.2 10.0 +0.7 0.9 +01
ws 32.1 12.7 3.5

Aquatic Part
Salvinia (P) 0.24 + 0.1 0.91 0.11 + 0.01 0.45 0,06 + 0.01 0.20
Elodea (E) 0.46 + 0.02 0.79 0.14 + 0.01 0.27 0.10 + 0.01 0.18
Guppies (G) 0.12 + 0.02 0.34 0.04 + 0.01 0.09 0.04 + 0.00 0.09
Water (W) 3.24 + 0.26 0.002 1.38 £0.21 0.001 0.48 + 0.03 0.001
Soil + Lake Mud (S) 24.5 + 1.56 0.14 7.63 + 0.67 0.14 1.54 + 0.03 0.12
Total (P, E, G, W, S) 28.6 9.30 2.22

Total
Terrestrial (T) 24.8 52.5 79.4
Aquatic (A) 28.6 9.3 2.2
THA 53.4 61.8 81.6

214C-Ring-Fonofos applied at 4 ppm (5.2 uCi) to upper 200 g Plano silt loam soil layer which was then placed on top of 800 g of untreated
soil. Recovery data, however, refer to the upper /2(U) and the lower %(L) layer of soil.

Per g of dry weight or per ml of water.
Except water, all materials were combusted to '4CO2.

These data emphasize the importance of plant type with re-
spect to both chemical uptake and metabolism.

Conclusions

1. Chemical behavior in the environment is affected by its
interactions with other chemicals.

2. Chemical/environmental component interactions (soil
type, plant abundance, and plant type) are of considerable
importance in understanding how chemicals move
through the food chain.

3. The soil-plant-water microcosm is useful in describing
transport and metabolism of chemicals under controlled
conditions.

Project Publications and Related Articles
Anderegg, B.N., Lichtenstein, E.P., and Kemp, J.D. Effects
of lindane on DNA, RNA and protein synthesis in corn roots.
J. Agr. Food Chem. 25(4):923-928 (1977).

Anderegg, B.N., and Lichtenstein, E.P. Effects of light inten-
sity and temperature on the uptake and metabolism of 14C-
phorate by oat, pea, and corn plants. From Ph.D. Thesis.
Available at University of Wisconsin Library and also on
microfilm, Ann Arbor, Michigan. Submitted for publication
(1980).

Anderegg, B.N., and Lichtenstein, E.P. A comparative study
of water transpiration on the uptake and metabolism of 14C-
phorate by C3 and Cy plants. J. Agr. Food Chem. 29:733-
738 (1981).

7


ih

| <4
| al iS

Figure 1. Schematic diagram of soil-plant-water microcosm.

cm deep, and 10 cm wide which are used for plant growth
and can be individually placed under different environmental
conditions in growth chambers. When rainfall or irrigation
are being simulated, the two soil containers are placed into
the ‘‘runoff container’ (10 cm high, 32 cm deep, 21 cm
wide) having a divider 20 cm high. This container in turn fits
into another {18 cm high, 31 cm deep, and 25.5 cm wide)
which by means of an adjustable wingnut screw makes it
possible to lift the container at one end. In this way, different
slopes are obtained, thus affecting the amount of runoff during
irrigation.

Runoff water containing soil was channeled into the aquarium
shown in Figure 1. Based on the size of these aquaria and the
slope of the soil, the amount of ‘‘rain’’ was adjusted accord-

2

—~\Wieitenininamenemaeencermeeettieacmma—<mmanm—s ~

ingly. To create more realistic conditions, a layer of lake bot-
tom mud was placed into the aquaria before runoff water
with soil entered them. When the water appeared clear after
settling of the soil, organisms such as water plants, fish or
insect larvae were introduced into the aquatic part of this
microcosm. Both the containers of the terrestrial part and
the aquaria can be placed into climatic chambers with differ-
ent environmental conditions.

This microcosm can be used to study the effects of rainfall
and other environmental conditions on the fate, movement,
the potential bioaccumulation, and interaction of one or sev-
eral test compounds after their application to soils and
crops. Thus, problems related to a particular test chemical
can be studied in fallow or plant-covered soil, in crop plants
grown in this soil, in runoff water containing soil particles, in
lake mud deposits, and in various organisms within the
aquatic part of this microcosm.

A model experiment using the microcosm was conducted
with [14C]phorate as the test compound because of
previous experience with phorate in a ‘‘model soil-plant
ecosystem’ (Lichtenstein et a/., 1974). Results obtained
with the terrestrial and aquatic portions of the microcosms
are partially presented in Table |. The total amounts of
radiocarbon in the various microcosm components were
determined by combustion. With freshly deposited insec-
ticide residues, 94% (91% terrestrial and 3% aquatic) of
the applied radiocarbon was recovered as opposed to 82%
with aged residues. This difference of 12% was noticed in
the terrestrial portions. It is possible that during the first 28
days of the experiment some compounds were lost due to
volatilization from the fallow soil.

With the freshly deposited insecticide, the aquatic insecticide
residues resulted from two ‘‘rainfalls’’, each of which yielded
a soil-water runoff containing 1.5% of the totally applied
radiocarbon. Two-thirds of the 14C recovered from the
aquaria was associated with the soil lake mud mixture.
Within the terrestrial part, most of the 14C residues were
recovered from the soil (65% of applied) while 26% was
recovered from the corn. Two-thirds of the total radiocarbon
content was contained in the leaves.

Corn plants from soils containing “‘aged’’ residues had con-
siderably less radiocarbon (19% of applied) than plants from
soils containing ‘‘fresh’’ residues (26% of applied). Expressed
on a per gram dry weight basis, corn leaves from soil with
“‘aged’’ residues contained 1.9% of the applied radiocarbon
while leaves from soils with ‘‘fresh’’ residues contained
3.1%. Since roots from both soils contained similar amounts
of 14C, quantitative differences were observed with leaves
of plants grown in the differently aged phorate-treated soils.
The amount of test compound transported via soil runoff is
likely a function of the physiochemical properties of the
chemical itself, such as vapor pressure, volatilization, and
water solubility. Moreover, factors such as soil type, slope
of the terrain, cover crop (presence and kind), and rain
(amount, duration, and intensity) are probably all directly
related to the mobility of the particular chemical. The fate
and metabolism of a test compound and its potential interac-
tion with other environmental chemicals can easily be studied
under different conditions (e.g., various temperatures or
light exposures). These results provide additional support
for the use of mode! ecosystems as research tools to aid in
the overall understanding of chemical behavior in the envi-
ronment.



Table |.
Microcosm?

Fate and Movement of ‘‘Aged” and ‘‘Freshly’’ Deposited [14C)phorate Soil Residues in a Plant-Soil Water

14C Recovered in Percent of Applied? to Soil

“'Fresh’’ Residues

“‘Aged"’ Residues

Recovered From Total Sample Per g Wtc Total Sample Per g Wt
Terrestrial Part
Soils (S) 65.6 +0.5 0.17 60.6 +04 0.15
Corn (C)
Leaves 16.9 +06 3.12 98 +04 1.92
Roots 8.7 +01 0.80 90 +0.5 0.86
Total (C) 25.6 18.8
Total (S + C) 91.2 79.4
Runoff 1
Water (W) 0.4 +01 0.0006 0.2 +0 0.0003
Soil (S) 1.1 40.1 0.08 1.1 +01 0.08
Total (W +S) 1 1.5 1.4
Runoff 2
Water (W) 0.5 +0.1 0.0008 03 +0 0.0005
Soil (S) 1.0 +0.1 0.08 1.1 40.1 0.08
Total (W + S)2 1.5 1.4
Total (1 + 2) 3.0 2.7
Aquatic Part
Soil and Lake Mud (S) 2.0 +0 0.03 1.5 40.1 0.02
Water (W) 0.8 +0.1 0.0008 06 40.1 0.0005
Guppies (G) 0.02 +0 0.08 0.01 +0 0.04
Salvinia (P) 0.2 £+0.1 0.29 0.1 +0 0.18
Total (S, W, G, P) 3.2 2.21
Total
Terrestrial (T) 91.2 79.4
Aquatic (A) 3.02 2.21
T+A 94.22 81.61

@ Results determined by combustion to 14CQz, except water, are averages of duplicated tests.

b Applied [14C]phorate at 4 ppm to 450 g of soil (9.83 Ci).
¢ Per gram of dry weight of per milliliter of water.

Data Base Development

Agricultural chemicals rarely, if ever, exist in isolation in the
environment. The transport of the chemical between eco-
system components, its effects and its degradation are af-
fected by environmental conditions (e.g., temperature,
moisture, and soil type), the presence of other chemicals,
the presence and type of plants as well as numerous other
factors. The balance of this project was dedicated to explor-
ing certain interactions that occur in ecosystems and how
they effect the movement of chemicals in particular into
plants as the first step in a food chain to man.

Comparative Chemical Transport and Metabolism

It has been commonly accepted that certain chemical pro-
perties can aid in predicting the environmental behavior of
chemicals; however, most environmental studies have dealt
only with the behavior of one or two compounds at a time.
These studies have provided a large volume of data on envi-
ronmental fate and behavior of individual compounds. How-
ever, the comparative behavior of different compounds is
difficult to assess since the environmental conditions asso-
ciated with the various studies can differ considerably.

One of the major areas in this project was the comparative
examination of the persistence, translocation and metabo-

lism of six different insecticides in two different soil types
under identical environmental conditions. The insecticides
used in order of increasing water solubility were [14C]DDT,
(14Cllindane, [14C]fonofos, [14C]parathion, [14C]phorate,
and [14C]carbofuran. These six chemicals represent three
major classes of insecticides; organochlorine, organophos-
phorus and carbamate. The soil plant test system consisted
of either Plano silt loam or Plainfield sand and oats (Avena
Sativa) maintained in the University of Wisconsin Biotron.
Table II provides a summary of the results from this study.
Total amounts of 14C residues recovered from insecticide-
treated loam soils plus oats grown in these soils were similar
with DDT and carbofuran. They were also higher than those
observed with the other insecticides. While most of the
[14C]DDT residues remained in the soils, most of the
[14C]carbofuran residues were recovered from oat leaves in
the form of carbofuran and 3-hydroxycarbofuran. 14C resi-
dues of all insecticides were more persistent in loam than in
sandy soil and sand-grown oats took up more 14C insecticide
residues than loam-grown oats. The more water-soluble in-
secticides [14C]phorate and [14C]carbofuran were more
mobile and were metabolized to a greater extent than insec-
ticides of lower water solubilities. Unextractable (bound)
14C residues in loam soil ranged from 2.8 to 29.1% of the
applied doses of [14C]DDT and [14C]parathion, respectively.

3