Chemosphere, Vol. 39, No. 10, pp. 1737-1769, 1999
Pergamon
© 1999 Elsevier Science Ltd. All rights reserved
0045-6535/99/$ - see front matter
PII: S0045-6535(99)00064-8
ENVIRONMENTAL FATE OF SYNTHETIC PYRETHROIDS DURING SPRAY
DRIFT AND FIELD RUNOFF TREATMENTS IN AQUATIC MICROCOSMS
Karen M. Erstfeld
Department of Environmental Sciences, Rutgers University
14 College Farm Road, New Brunswick, NJ 08903
Phone (732) 932-9817, FAX (732) 932-8644
(E-mail: Kerstfeld@~aol.com)
(Received in USA 24 June 1998; accepted 21 January 1999)
Received Date:
ABSTRACT
The aquatic fate and persistence of synthetic pyrethroids under spray drift and field
runoff treatment regimes were determined in outdoor pond microcosms.
In this paper, the
experimental design and construction of outdoor microcosms is presented, as well as the aquatic
fate oftralomethrin and deltamethrin.
Tralomethrin is rapidly degraded to deltamethrin, with a half-life of 12.7 hours under
spray dritt conditions. Degradation profiles of tralomethrin in water indicated rapid conversion
of deltamethrin and to less active isomers and then to decamethrinic acid (BR2CA). After 24
hours, the percent radioactivity of tralomethrin was 25% of the test material in the water column.
In sediment, tralomethrin was immediately converted to deltamethrin.
© 1999 Elsevier Science Ltd. All rights reserved
1737
1738
Deitamethrin is rapidly degraded with a half-life of 8 to 48 hours, depending on
mechanism of introduction into water. Degradation profiles of deltamethrin in water indicated
rapid conversion of deltamethrin to decamethrinic acid (BR2CA), comprising approximately
90% of the radioactivity in the aqueous phase at 168 hours.
Extraction and analysis of fathead minnows (Pimephales promelax) after 96 hours
revealed that tissue residues contained parent compounds and metabolites ct-R-deltamethrin,
trans-deltamethrin and Br2CA. Fish residues are directly related to aqueous concentrations, thus
bioavailability under field runoff regimes were an order of magnitude lower than tissue residues
under spray drift conditions. Plant tissue was found to significantly accumulate pyrethroids.
Key Words: aquatic fate, microcosms, spray drift, field runoff, deltamethrin, tralomethrin,
pyrethroids
Introdoction
Although most investigations of environmental fate are laboratory-based, outdoor pond
microcosms and mesocosms have been used in recent years in ecological risk assessment of
pesticides,
providing integrated
information beyond individual
laboratory studies [1-7].
Microcosms can allow for the monitoring of residue concentrations of parent and degradation
products in sediment, water, plants and in organisms as a function of time and can provide
detailed exposure information, not only for parent compound, but also for degradation products,
as well. Results from this investigation are intended to aid the interpretation of ecological fate
data that has been collected from individual laboratory investigations, in order to provide more
realistic fate and exposure information for a comprehensive ecological risk assessment for
tralomethrin and deltamethtin.
Tralomethrin, is the active ingredient of Scout 0.3 EC and Scout Xtra 0.9 EC.
Deltamethrin, is the active ingredient of Decis 2.5 EC.
pyrethroid insecticides for use on cotton.
Both compounds are synthetic
The toxicity of synthetic pyrethroids to aquatic
organisms has in established in laboratory studies and are typically in the low ppb range for fish
[l].
Few studies have been performed to evaluate the dynamics of pyrethroid degradation in
aquatic ecosystems. Previous studies have reported the degradation of the synthetic pyrethroid
deltamethtin in ponds to be rapid, with half-lives less than 24 hours [2,3].
1739
A series of pond outdoor microcosms were designed and constructed to determine the
fate and persistence of tralomethrin and deltamethrin, two synthetic pyrethroid insecticides,
under spray drift and field runoff treatment regimes.
The objectives were to i) determine the
fate and persistence of tralomethrin and deltamethrin in a simulated outdoor pond environment.
ii) determine their relative distribution in water, sediment, macrophytes, and fish; iii) compare
their aquatic fate under simulated spray drift and field runoff treatment regimes, and iv)
determine the major degradation products in an aquatic environment. The chemical structures of
tralomethrin, deltamethrin and its degradation products are shown in Figure 1.
Materials and Methods
Test Materials
Radiolabeled 14C (methyl labeled) Tralomethrin (RU 25474, [1-R-[la(S*),3c~]]2,2,dimethyl-3 -(1,2,2,2 -tetrabromoethyl)-cyclopropane
carboxylic
acid,
cyano
(3-
phenoxyphenyl)methyl ester, CAS # 66841-25-6, a solution in toluene, was received from
Roussel Uclaf, Paris, France.
This material had a specific activity of 60 mCi/mmole and a
radiopurity of 97.7%. Traiomethrin has a molecular weight of 667.03 mg/mmole. Radiolabeled
14C (methyl labeled) Deltamethrin (RU22974, [1R-[1-R-[la(S*),3et]]-3-(2,2,dibromoethenyl)2,2dimethylcyclopropanecarboxylic acid, cyano(3-phenoxyphenyl)methyl ester, CAS#52918-635), had a specific activity of 60 mCi/mmole and a radiopurity of 100%. Deltamethrin has a
molecular weight of 505.22 mg/mmole.
approximately -80 °C in the dark.
Test materials were stored in a freezer maintained at
The structures of Tralomethrin and Deltamethrin, including
the position of the radiolabel, and its degradation products are shown in Figure 1. The
degradation products include ~tR-Deltamethrin, trans-Deltamethrin and Decamethrinic acid
(Br2CA).
Microcosm Destgn and Construction
A series of three microcosms (one series for tralomethrin, the other series of three for
deltamethrin) were constructed of fiberglass - one microcosm each to simulate spray drift, field
runoff and control treatment regimes. These cylinders, each 1.2 m in diameter and 1.2 m tall,
were placed on end in two 3 m diameter by 1.2 tall fiberglass cylinders (three smaller tanks
1740
~!:i~,~,i,,'~0,,,,,'~~~0
-Br
~
-* *
~
O
CN
~/
•
tralomethrin
* *
n
CN
~,~ ,,%c,,.~
....~,~~o,~
~/c=~'%..J~....."~o.."~L~ ~L~
deltametbri~
* *
H3C .CH:
CN
O
'1
I
_
_
Br'~c_~c/
Br /
tr~-d¢Ita~etkd~
..* *.,..
Br/C'-=-C',,,,,,,,~,,....'C.o~**'C~O~
l~r~
o
H~_ .~.r~ II
CN
I
_
=-R-deltamethrin
s~
.,~ .~.. ,o,
Br/C = C,,,,,,,,,~
..,....."C~.OH
Br~CA
* - Denotes radiolabel location
Figure ]. Chemical structures oftralomcthrJn, de]tamcthfin and degradation products,
1741
within one larger), resting on a level bed of sand.
The water level was maintained between
0.85 and 0.95 m (990 - 1100 liters) throughout the investigation. Approximately a 6cm layer of
sediment was placed in aluminum trays (14 cm wide by 29.8 cm long by 8.3 cm deep, 150 Kg
total mass of sediment). Shoots of the narrow leaf pond weed (Potamogeton sp.) were inserted
into the sediment trays. Once the sediment trays and plants were in place, water was slowly
pumped into each microcosm vessel, with the initial water depth was approximately 1050 liters.
In addition, 21 petri dishes of sediment (10 cm by 1.5 cm deep, with 1.0 cm sediment, 2100 g
total mass of sediment) were deployed on the bottom of each microcosm approximately 3 weeks
prior to treatment. The number and size of the sediment trays and Petri dishes were selected in
order to simulate the same ratio of water to sediment surface area typical for natural ponds.
Prior to construction, the microcosm tanks were washed with a mild detergent and
rinsed with water. The large tanks were filled with water and used as water baths, designed to
maintain water temperatures between 19 and 24 °C.
In order to maintain water temperature, a
chiller unit was used and circulated water at approximately 1.8 gallons/minute. This flow rate
circulated all water in the water baths approximately 1.5 times every 24 hours. The water baths
were wrapped in insulation to minimize heat loss due to radiative cooling.
Microcosm Preparation and Acclimation
Preparation of the microcosms began by collecting water, sediment and aquatic
macrophytes from a freshwater pond near Wareham, MA.
The narrow leaf pond weed
(Potamogeton sp.) was selected as the aquatic maerophyte, based on its abundance and apparent
good health when collected. As the pond weed senesced, 800 g of bladderwort (Utricularia ~p)
was used as a replacement species prior to dosing based on its health and abundance in
conditions similar to those found in the microcosms.
Samples of sediment and water were
tested for levels of chlorinated, organophosphate and pyrthroid pesticides.
No detectable
residues levels were found (typically, LOD <0.05 ~tg/L, depending on specific analyte).
Sediment was characterized for pH, percent organic matter, cation exchange capacity and
textural classification and was found to be a loamy sand (74% sand, 22% silt and 4 % clay). The
pH was determined to be 5.5; the organic carbon content was 3.2%; and the CEC was analyzed
to be 5.7meq/100 g.
1742
The microcosms were set up approximately eight weeks prior to treatment.
Approximately three weeks prior to treatment, 21 Petri dishes of sediment (10 cm diameter by
1.5 cm deep, with 1.0 cm of sediment, 2100 g of sediment) were deployed on the bottom of each
test tank. The sediment placed in these dishes was collected from the same location as that used
for the maerophytes. This sediment was stored frozen in the interim between collection and use.
The number and size of the sediment trays and Petri dishes were selected in order to simulate the
same ratio of water to sediment surface area used in model calculations and typical for natural
ponds (total sediment mass 152.1 kg) [8, 9 ].
Approximately three weeks prior to initiation of the tests, approximately 500, 60 to 90
day old fathead minnows (l~imephales promelas) were added to each set of spray drift, field
runoff and control microcosms. In each treatment tank, the fish were placed in five cages (5 fish
per cage) suspended from the top of the tanks to facilitate their removal during sampling. Each
control tank received 7 cages with five fish in each. In addition, the remaining fish (412 per test
type) were divided among 8 larger cages, four of which were placed into each treatment tank..
Fish from the smaller cages were collected at specified intervals for LSC analyses, and fish from
the larger cages were collected for both liquid scintillation counting (LSC) and high performance
liquid chromatography (HPLC) analyses. Fine mesh nets were used to transfer fish from the
culture unit to a transport vessel and to the cages. Fish were fed every day and observed for
mortality. No fish mortality occurred prior to treatment.
Test (?oncentrations and Application
For the spray drift test, test materials were applied on August 20, 1990. Deltamethrin
was applied at 0.018 Ibs/acre for the spray drift treatment.
Based on a microcosm vessel
diameter of 1.22 m, 2357 lag of deltamethrin was applied to the spray drift microcosm (nominal
concentration 2.208 lag/L). For the spray drift test, tralomethrin was applied at the maximum
label rate of 0.024 lbs/acre, an equimolar application to deltamethrin (nominal concentration
2.941 lag/L). To prepare the deltamethrin application to be used in the spray drift treatment, 27.6
mL of a 93.8 lag/mL of 14 C Deltamethrin stock solution was added to a 100 mL amber glass
wide mouth bottle. To this was added 103.7 laL of the formulation blank, and the solution was
evaporated under a gentle stream of nitrogen to remove the acetone. The resultant solution
simulates a Decis 2.5 EC formulation at 25 grams per liter, approximately 0.2 pounds per gallon.
1743
For the spray drift application, tralomethrin was applied at the maximum label rate of 0.024
lbs/acre, an equimolar application to deltamethrin.
To prepare the tralomethrin application to be
used in the spray drift treatment, 28.8 mL of a 120 lag/mL 14 C Tralomethrin stock solution was
added to a 100 mL glass wide mouth bottle. To this was added 95.8 laL of the formulation blank,
and the solution was evaporated under a gentle stream of nitrogen to remove the acetone. The
resultant solution simulates a Scout 0.3 EC formulation at 0.3 pounds per gallon.
Spray drift test solutions were applied uniformly to the surface of the water of their
respective microcosms using a pressurized thin layer chromatography spray applicator. To
ensure uniform test material was sprayed across the water surface into four equal quadrants.
After application, a 110 mL rinse of NANOpure water was applied, followed by 25 mL acetone
in order to maximize the amount of test material application.
All other tanks were covered
during spray delivery to prevent cross-contamination.
For the field runoff experiment, test materials were applied to the microcosms on August
28, 1990. Deltamethrin was applied at 0.00576 lbs/acre (759 lag per microcosm; nominal
concentration 0.711 p,g/L) and tralomethrin was applied at 0.00768 lbs/acre (1004 lag per
microcosm; nominal concentration 0.941 lag/L). These values were 32% of the spray drift values
and were intended to simulate a 3.2% runoff from a 10 acre field into a 1 acre pond [8, 9]. To
simulate field runoff, test material was adsorbed onto clay and a slurry prepared. The slurry was
uniformly delivered immediately below the surface of each microcosm vessel using a separatory
funnel.
To prepare the deltamethrin application to be used in the field runoff test, 8.90 mL, of the
93.8 lag/mL 14C- deltamethrin stock solution was added to 330 gram clay (100% kaolinite). For
the tralomethrin application, 9.20 mL of the 120 ktg/mL 14C- tralomethrin stock solution was
added to 330 gram clay. The clay was mixed in a Waring blender for one minute, after which it
was transferred to a round bottom flask. The flask was covered with aluminum foil and placed
under a gentle stream of nitrogen to evaporate the acetone. After the acetone had been removed,
exactly 300 grams of the dosed clay was removed and placed in a 3000-mL volumetric flask.
The flask was filled with NANOpure water to the 1,000 mL mark. The remainder of the dosed
clay was retained for confirmation of the dose preparation by LSC and HPLC analyses. Slurry
was applied to the test vessels using 2 liter separatory funnels, with the funnel mouth held just
below the surface of the water.
Delivery was performed in a circular manner, to provide a
1744
uniform distribution of slurry in the test vessels and separatory funnels were continuously
agitated during application to hold the clay in suspension to ensure a uniform slurry. The control
tanks received untreated slurry.
SAMPLING AND ANALYSIS
Analyses of the water, sediment, plants and fish removed from the spray drift, field
runoff`and control microcosm vessels were conducted using liquid scintillation counting for total
~4C assessment,
and with the exception of plant tissue, by high performance liquid
chromatography with radiometric detection to determine chemical speciation of 14C labeled
compounds. The sampling methods and frequency of sampling are described below. For details
concerning the analytical methods used, the reader is referred to [10].
Water
Samples of the microcosm water were collected at the following intervals: I hour prior to
treatment, and 0.5, 1, 2, 4, 8, 24, and 96 hours after treatment. A final sample was collected 7
days after treatment. Duplicate water samples were collected and analyzed at all times. From
0.5 to 4 hours after treatment, water samples were collected from the treated tanks at depths of 1
-10 cm, 40-50 cm, 80-90 cm (top, middle, and bottom). The pretreatment, 8 hour, 24 hour, 96
hour, and day 7 samples were collected as depth-integrated water samples. A depth-integrated
water sample was collected from the control vessels at all sampling intervals. All water samples
were two liter in volume, one liter for total 14 C assay and one liter for HPLC analysis with
radiometric detection. The latter samples were treated with concentrated hydrochloric acid and
extracted with hexane:ethyl acetate (1:1) prior to filtration through sodium sulfate. The extracts
were then rotary evaporated and just before dryness, the residue was reconstituted in hexane for
HPLC analysis.
Samples for the total C14 assay were processed as described above, except that
after rotary evaporation, the residue was reconstituted in approximately 5 mL methanol and 15
mL Monophase was added to the scintillation vial. Depth specific samples were removed from
each test vessel using a siphon into l-liter volumetric flasks, while depth integrated samples were
removed using a glass tube to take a "core" of water. The limit of detection for tralomethrin,
deltamethrin and degradates in water was set at 2 ng/L.
1745
Sediment
Sediment dishes were collected for analysis prior to test material application and after
treatment at the following hours: 1, 2, 4, 24, and 96. A final sample was collected 7 days after
treatment.
Two dishes were removed from the treatment vessels and analyzed separately for
each sample interval; control tanks had only one dish analyzed per sample interval. At each
sampling interval, three quality control sediment samples were prepared and analyzed by both
LSC for total 14C and HPLC for compound specific analyses.
Approximately 100 grams
sediment samples were collected from each test microcosm, with duplicate 50 mL subsamples
extracted with hexane:acetone (8:2). The limit ofquantitation for tralomethrin, deltamethrin and
the degradation products in sediment was set at 50 ng/kg
Biota
Five fish were randomly selected from the microcosms for LSC combustion just prior to
pyrethroid addition; 1, 2, 4, 24, and 96 hours post-treatment; and 7 days after application. This
allowed for five separate 14-C determinations
at each sampling interval.
In addition,
approximately 200 fish were removed from each treatment microcosm vessel at 96 hours after
test initiation, with separate extraction and analysis of 100 fish for tralomethrin, deltamethrin and
metabolites. Samples were homogenized in a Waring blender and extracted four times with 100
mL hexane/acetone (1:1 ). The hexane layers were combined and analyzed for ~4C residues using
HPLC with radiometric detection.
The acetone/hexane phases were combined and back
partitioned twice with 100 mL hexane. The remaining acetone/aqueous fraction was acidified to
pH 2 with concentrated hydrochloric acid and extracted twice with methylene chloride.
The
methylene chloride extracts were combined with the hexane back partition extracts and analyzed
by HPLC-RAM and described as acetone/aqueous extract.
The remaining acetone/aqueous
extracted was assayed by LSC for non-extractable residues. Finally, the tissue remaining was
also quantified for non-extractable residues.
The detection limit for each fish sample is
dependent upon the counting efficiency and the weight of the fish, thus detection limit varied
among samples. The limit of detection ranged from <0.14 to <1.40 ~tg/kg.
Macrophytes were sampled prior to test treatment, 24 and 96 hours after treatment, and 7
days after treatment. A portion of plant material (Utricularia sp) from below the water surface
was removed from each of the tanks using a clean grappling hook. Whole plant samples were
1746
weighed, blotted dry with paper towels and dried for several days at room temperature prior to
subsampling (duplicate 10 g samples) and combustion in a Packard Model 306 Sample Oxidizer.
Total 14C content was determined by liquid scintillation counting.
RESULTS AND DISCUSSION
Water ( ~oncentrations
Depth specific analyses of total 14C residue revealed little differences existed between
the various depths of each microcosm vessel. No concentration gradient was apparent even as
little as 30 minutes after dosing.
Consequently, all calculations were performed with mean
concentrations, independent of depth.
Tralomethrin spray drift water concentrations of total 14 C-residues (uncentrifuged
samples) decreased by 44%, but remained relatively high throughout the seven day period, at
1.78 + 0.180~tg/L 30 minutes after treatment, decreasing to 0.989 + 0.0591ag/L after seven days.
The nominal concentration for tralomethrin was 2.94 p,g/L, based on the applied quantity of
tralomethrin and the initial volume of water vessels, respectively.
At one hour post treatment
from the tralomethrin spray drift vessel, the uncentrifuged middle depth samples contained 1.89
_+0.071 p.g/L, while the centrifuged samples contained 1.60/ag/L. Similarly, at seven days post
treatment, the uncentrifuged integrated depth samples contained 0.989 _+ 0.059lag/L, while the
centrifuged samples contained 0.949 lag/L. Total 14C concentration for the control vessel were
<0.289rig/L, throughout the time course of the experiment.
Tralomethrin field runoff microcosm water concentrations of total 14 C-residues
(uncentrifuged samples) remained consistently lower than in the spray drift application
throughout the seven day period, at 0.174 _+ 0.0651ag/L 30 minutes after treatment of
tralomethrin decreasing to 0.0940 +_ 0.002~,tg/L after seven days. Comparison of centrifuged
water concentrations with those of uncentrifuged samples revealed small differences, but larger
ones than observed in the spray drift application implying that significant quantities of the
applied test materials did not desorb from the applied runoff solids. At one hour post treatment
from the tralomethrin vessel, the uncentrifuged integrated depth samples contained 0.122 _+0:022
~g/L, while the centrifuged samples contained 0.0606 ~tg/L (nominal applied concentration 0.94
~,tg/L). However, at seven days post treatment, the uncentrifuged integrated depth samples
1747
contained 0.0940 lag/L, while the centrifuged samples contained 0.0791 p.g/L, a significantly
smaller difference due most likely to settling of the suspended solids. Total suspended solids
concentrations were determined to be 50 and 23 mg/L, respectively, for the field runoff and
spray drift microcosms after seven days.
Water concentrations are presented for tralome~hrin and its the degradation products,
cis-
deltamethrin, ct-R-deltamethrin, trans-deltamethrin and Br2CA and are presented in Figures 2
and 3. Tralomethrin rapidly degraded to deltamethrin, with a calculated half-life for tralomethrin
of 6.9 hours (determined from time 0.5 to 24 hours). Deltamethrin formed in the tralomethrin
application, degraded with a half-life of 81.0 hours (determined from time 24 to 168 hours) to the
other products, with BR2CA being the degradative end point for this seven day study.
Data for the spray drift deltamethrin microcosm vessel was similar, with 1.11 _+
0.047~tg/L in the uncentrifuged middle depth water samples at one hour post application, and
1.17 ~tg/L in the comparable centrifuged samples.
At seven days post treatment, the
uncentrifuged integrated depth samples contained 0.698 + 0.004 p.g/L, while the centrifuged
samples contained 0.695 ~tg/L. Water concentrations were 1.160 + 0.058 ~tg/L 30 minutes after
the spray drift treatment of deltamethrin decreasing by 40% to 0.698 + 0.004 p.g/L after seven
days.
Comparison of centrifuged water concentrations with those of uncentrifuged samples
revealed small differences, implying that little of the applied test materials were adsorbed to
suspended solids. Total suspended solids concentrations were determined to be 69 and 22 rag/L,
respectively, for the field runoff and spray drift microcosms after seven days.
The nominal
concentration for deltamethrin was 2.21 ~tg/L immediately following dosing, based on the
applied quantity of deltamethrin and the initial volume of water vessels, respectively.
Total
14C concentration for the control vessel were <0.289ng/L, throughout the time course of the
experiment. Data from the deltamethrin application, using time 0.5 to 24 hours, corroborated the
half-life determined for deltamethrin from the tralomethrin vessel with the result being 18.0
hours. HPLC separation of the products found in water samples was excellent and the use of
radiometric detection removed interferences typically associated with UV detection.
The
degradation profile for deltamethrin under spray drift and field runoff conditions is presented in
Figures 2 and 3.
In field runoff deltamethrin microcosm, aqueous concentration of total C14 ranged from
0.0937 + 0.013p.g/L in the uncentrifuged middle depth water samples at one hour post
1748
Figure 2. Degradation product water concentrations versus time comparing tralomethrin and
deltamethrin under spray drift and field runoff conditions.
Tralomethrin
- Spray
Drift
Tralomethrin
60
- Field R u n o f f
• ge~me~na
• an-|- l~l~w~nl
• t¢- I N l t a m ~
A
o
11,|¢~
250
2O0
~
150
~
loo
30
20
~0
5O
~.
0
0
24
48
72
96
120
Time ( H o u r s )
Deltamethrin
- Spray
144
0
168
--
_
. i . . .~
24
Drift
~J~..~ ~ . ~ . ~. ~ . ~ .~ . ~
48
72
96
~20
T i m e (Hours)
144
168
Deltamethrin - Field Runoff
5OO
~
450
v e-II-~el~let~,~ .
• t~l)elt~me~la
,oo
~
• I~- I -Dll~Ie~Itheil
45
• L C - ~ I t ~
~ ~¢~
~r~r.~
A
40
~
20
~" ~so
-~
.'oo
~
250
~
~oo'
.~
~o
~00
~
50
.
24
48
72
Time
96
. . , ...~
-.~
120
I~4
168
(Houre)
~.',
0
• [ • ~.
24
'
48
. . . . . . .
~ .],,,
,i . . . . . . .
72
96
~20
T i m e (Houre)
10,4
; *
168
1749
Figure 3. Plot of the composition of the 14C residues in the water phase at 168 hours comparing
tralomethrin and deltamethrin under spray drift and field runoff conditions.
100
9O
0~
80
~
70
.2
,.o
60
¢-~
~
50
.~
~
40
.~
.>
~
.,~
30
~
~0
~ m
0
Tralo
Spray
Drift
~
['C[Tr[
~
~
1
Delta
Spray
Drift
Tralomethrin
DeRamethrin
a-R-Deltamethrin
lrans-De|LamethrJn
Br2CA
Tralo
Field
Runoff
Delta
Field
Runoff
1750
application, and 0.0442 p-g/L in the comparable centrifuged samples (nominal concentration
applied 0.711 p-g/L). At seven days post treatment, the uncentrifuged integrated depth samples
contained 0.093 _+ 0.0012 p.g/L, while the centrifuged samples contained 0.0985 p-g/L. HPLC
data from the deltamethrin application determined a half-life of 8.1 hours.
During the course of this study, 4.02%, 3.07%, 0.92% and 0.99% of total 14-C material
was removed by water in the tralomethrin spray drift, deltamethrin spray drift, tralomethrin field
runoff and deltamethrin runoff treatments, respectively.
It is estimated that 29.1%, 27.7%,
8.98% and 11.6% of total 14-C material remaining in the aqueous phase at the end of the study,
in the tralomethrin spray drift, deltamethrin spray drift, tralomethrin field runoff and
deltamethrin runofftreatments, respectively (Table 1).
Sediment ( ;oncentrations
Sediment samples were collected for analysis by both LSC and HPLC at each of the same
intervals as the water, with the exception of 0.5 and 8 hours. Results of the LSC analysis for
total 14C revealed that the sediment concentrations remained relatively constant throughout the
seven day test period.
Concentrations of tralomethrin in the spray drift microcosm ranged from
4.40 + 2.44 p-g/kg at I hour post treatment to 16.4 + 15.8 p-g/kg after 96 hours, while those for
the deltamethrin spray drift application ranged from to 2.38 + 0.778 p-g/kg after 1 hour post
treatment and 12.8 _+ 4.78 p.g/kg at 96 hours, respectively.
By 7days, the concentration of
tralomethrin had dropped to 11.0 + 2.41 ~tg/kg, whereas the concentration of deltamethrin
dropped to 6.82 + 0.863 p.g/kg in the spray drift microcosms. Concentrations oftralomethrin in
the runoff microcosm ranged from 15.4 + 15.64 p-g/kg at 1 hour post treatment to 80.7 + 57.06
p-g/kg after 96 hours, while those for the deltamethrin runoff application ranged from to 18.3 _+
2.55 p-g/kg after I hour post treatment and 63.1 _+ 36.98p-g/kg at 96 hours, respectively. By 7
days, the concentration of tralomethrin was 82.6 + 54.38 p,g/kg, whereas the concentration of
deltamethrin was 93.3 _+ 42.07 p,g/kg in the spray drift microcosms.
The control microcosms
had concentrations of<50 ng/kg throughout the exposure period.
Chemical specific analyses by HPLC for the spray drift and runoff microcosms are
presented for tralomethrin, deltamethrin, as well as the degradation products, o~-R-deltamethrin,
trans-deltamethrin and BR2CA in Tables 2 through 5, respectively. After 1 hour, the tralomethrin
1751
Table 1. Total mass balance for the tralomethrin and deltamethrin spray drift and runoff
microcosms removed during experiment and remaining at 168 Hours
Medium
Tralomethrin
Deltamethrin
Tralomethrin
Deltamethrin
Spray Drift
Spray Drift
Runoff
Runoff
(~tg)
(~tg)
(~g)
126
72.3
9.23
7.54
removed
(4.02%)
(3.07%)
(0.92%)
(0.99%)
Sediment
5.74
3.24
35.2
21.1
removed
(0.18%)
(0.14%)
(3.51%)
(2.78%)
39.0
20.7
2,24
2,32
(1.24%)
(0.86%)
(0.23%)
(0.31%)
46.3
39.3
5.31
3.98
(!.5%)
(1.7%)
(0.53%)
(0.52%)
653
90.2
87.1
(8.98%)
(11.6%)
264
292
Water
Fish
removed
Plants
removed
Water
913
Remaining
(29.1%)
Sediment
34.7
20.7
(1.10%)
(0.88%)
(26.3%)
285
138
12.4
16.1
Remaining
(9,08%)
(5.85%)
(1.24%)
(2.12%)
Adsorbed to
37.2
12.5
3.51
5.19
Vessel Walls
(1.19%)
(0.53%)
(0.35%)
(0.68%)
Remaining
Plants
Totals
1487
(47.4%)
(27.7%)
(~tg)
960
(40.7%)
(38.4%)
422
435
(42.0%)
(57.3%)
1752
Table 2. Sediment concentrations determined by HPLC for the tralomethrin spray drift
microcosm vessel
Sampling
Interval
(hours)
Tralomethrin cis.Delta.
(RU25474) (RU22974)
(ng/kg)
(ng/kg)
=-R-Delta. tr-Delta.
Br=CA
(RU23938) (RU26979) (RU23441)
(ng/kg)
(ng/kg)
(ng/kg)
Pretreatment
< 50.0
< 50.0
< 50.0
< 50.0
< 50.0
< 50.0
< 50.0
< 50.0
< 50.0
< 50.0
1
< 50.0
310
178
327
< 50.0
< 50.0
< 50.0
< 50,0
< 50.0
< 50.0
2
54.8
255
138
414
< 50.0
< 50.0
< 50.0
< 50.0
< 50.0
< 50.0
4
182
485
353
294
68.8
< 50.0
< 50.0
< 50.0
< 50.0
< 50.0
24
650
169
630
169
400
91.3
< 50.0
< 50.0
< 50.0
< 50.0
96
727
< 50.0
1440
< 50.0
739
< 50.0
< 50.0
< 50,0
< 50.0
< 50.0
206
66.1
821
355
550
86,5
< 50.0
< 50.0
177
< 50.0
168
1753
Table 3. Sediment concentrations determined by HPLC for the deitamethrin spray drift
microcosm vessel
Sampling
Interval
(hours)
Pretreatment
cis-Delta.
(RU22974)
(ng/kg)
¢z-R-Delta.
(RU23938)
(ng/kg)
tr-Delta.
(RU26979)
(ng/kg)
Br=CA
(RU23441)
(ng/kg)
< 50.0
< 50.0
< 50.0
< 50.0
< 50.0
< 50.0
< 50.0
< 50.0
1
225
102
87.1
< 50.0
< 50.0
< 50.0
< 50.0
< 50.0
2
150
151
< 50.0
77.6
< 50.0
< 50.0
< 50.0
< 50.0
4
106
< 50.0
< 50.0
< 50.0
< 50,0
< 50.0
<50.0
< 50.0
24
349
274
113
< 50.0
< 50.0
< 50.0
< 50.0
< 50.0
96
1060
906
520
248
< 50.0
< 50.0
< 50.0
< 50.0
<50,0
147
< 50.0
< 50.0
111
106
168
146
424
1754
Table 4. Sediment concentrations determined by HPLC for the tralomethrin field
runoff microcosm vessel
Sampling
Interval
(hours)
Tralomethrin cis-Delta.
(RU25474)
(RU22974)
(ng/kg)
(ng/kg)
=.R-Delta.
(RU23938)
(ng/kg)
tr-Delta.
(RU26979)
(ng/kg)
Br=CA
(RU23441)
(ng/kg)
Pretreatment
< 50.0
< 50.0
< 50.0
< 50.0
< 50.0
< 50.0
< 50.0
< 50.0
< 50.0
< 50.0
1
1560
103
684
< 50.0
< 50,0
< 50.0
< 50.0
< 50.0
< 50.0
< 50.0
2
2370
137
12600
1570
<50.0
<50,0
< 50.0
< 50.0
< 50.0
< 50,0
4
289
707
20~0
3840
< 50.0
< 50.0
< 50.0
< 50.0
<50.0
< 50.0
24
5090
2040
11000
6430
423
<50.0
< 50.0
< 50.0
< 50.0
< 50.0
96
1600
1350
6190
8450
751
505
< 50,0
< 50.0
< 50.0
< 50.0
168
1060
1340
7950
13500
819
1140
< 50.0
< 50.0
< 50.0
< 50.0
1755
Table 5. Sediment concentrations determined by HPLC for the deltamethrin field
runoff microcosm vessel
Sampling
Interval
(hours)
c/s.Delta,
(RU22974)
(ng/kg)
a-R-Delta,
(RU23938)
(ng/kg)
tr-Delta.
(RU26979)
(nglkg)
Br=CA
(RU23441)
(ng/kg)
Pretreatment
< 50.0
< 50.0
< 50.0
< 50.0
< 50.0
< 50.0
< 50.0
< 50.0
1
297
4100
<50.0
< 50.0
< 50.0
< 50.0
< 50.0
< 50.0
2
1970
543
< 50.0
< 50.0
< 50.0
< 50.0
< 50.0
< 50.0
4
365
5390
< 50.0
< 50.0
< 50.0
< 50.0
<50.0
< 50.0
24
1970
692
146
< 50.0
< 50.0
<50.0
< 50.0
<50.0
96
3030
11600
255
738
< 50.0
< 50.0
< 50.0
172
168
14000
8800
968
707
< 50.0
< 50.0
< 50.0
87.3
1756
spray drift treatment sediment contained 180 + 183.5 rlg/kg tralomethrin, 252.5 + 105.4 rlg/kg
cis-deltamethrin, <50.0 rlg/kg ct-R-deltamethrin, <50.0 qg/kg trans-deltamethrin and < 50.0
rlg/kg Br2CA. After 7 days, the tralomethrin spray drift treatment sediment contained 136.1 _+
98.9 qg/kg tralomethrin, 588.0 + 329.5 rlg/kg cis-deltamethrin, 318.3 + 327.7 rlg/kg ct-Rdeltamethrin, <50.0 rlg/kg trans-deltamethrin and 113.5 + 89.8 rlg/kg Br2CA. In comparison,
after 1 hour, the tralomethrin field runoff treatment sediment contained 831.5 + 1030.3 rlg/kg
tralomethrin, 367.0 _+ 148.3 rlg/kg cis-deltamethrin, <50.0 qg/kg ~t-R-deltamethrin, <50.0 rlg/kg
trans-deltamethrin and < 50.0 rlg/kg BrzCA.
After 7 days, the traiomethrin field runoff
treatment sediment contained 1,470 _+ 183.9 qg/kg tralomethrin, 10,725 _+ 3924.4 rlg/kg cisdeltamethrin, 979.5 _+ 227.0 rlg/kg c~-R-deltamethrin, <50.0 rlg/kg trans-deltamethrin and <50
qg/kg Br2CA (Figure 4). It is clear that tralomethrin degraded to the same degradation products
identified for the water phase, but half-life calculations were not possible for the sediment.
After 1 hour, the deltamethrin spray drift treatment sediment contained 163.5 _+ 87.0
qg/kg cis-deltamethrin, 68.6 + 26.2 qg/kg c~-R-deltamethrin, <50.0 rlg/kg trans-deltamethrin
and < 50.0 rlg/kg Br2CA. After 7 days, the deltamethrin spray drift treatment sediment contained
285.0 + 196.6 rlg/kg cis-deltamethrin, 98.5 _+68.6 rlg/kg ~x-R-deltamethrin, <50.0 ~qg/kg transdeltamethrin and 108.5 + 3.54 rlg/kg Br2CA. In comparison, after 1 hour, the deltamethrin field
runoff treatment sediment contained 2,198.5 _+2,689.1 rlg/kg cis-deltamethrin, <50.0 qg/kg aR-deltamethrin, <50.0 qg/kg trans-deltamethrin and < 50.0 rlg/kg BrzCA. After 7 days, the
deltamethrin field runoff treatment sediment contained 11,400.0 _+ 3,677.0 rlg/kg cisdeltamethrin, 837.5 + 184.6 rlg/kg ~t-R-deltamethrin, <50.0 rlg/kg trans-deltamethrin and 68.7 +
26.4 rlg/kg BrzCA (Figure 4). The concentrations of deltamethrin remained much more stable in
the sediment, and degradation is demonstrated not by loss of parent tralomethrin or deltamethrin,
but rather by appearance of a-R-deltamethrin and BR2CA. This may be due to either
degradation of adsorbed chemical, or by adsorption of degradation products formed in the
aqueous phase.
During the course of this study, 0.18%, 30.14%, 3.51% and 0.2.78% of total 14-C
material was removed by sediment in the tralomethrin spray drift, deltamethrin spray drift,
tralomethrin field runoff and deltamethrin runoff treatments, respectively.
It is estimated that
1.10%, 0.88%, 26.3% and 38.4% of total 14-C material remaining in the sediment phase at the
1757
Figure 4. Plot of the composition of the 14C residues in the sediment at 168 hours comparing
tralomethrin and dcltamethrin under spray drift and field runoff conditions.
1 O0
9O
m
0
~;
80
~
70
-~
.~o
.~
60
•r~
50
.~
~
40
L"
"~
30
e
20
'~
~0
0
I
Tralo
Spray
Drift
~
Delta
Spray
Drift
B
~
[~
Tralomethrin
~
trans-Deltamethrin
~
Br~CA
DeRamethrin
a-R-Deltamethrin
!
Tralo
Field
Runoff
Delta
Field
Runoff
1758
end of the study, in the tralomethrin spray drift, deltamethrin spray drift, tralomethrin field runoff
and deltamethrin rtmofftreatments, respectively (Table I ).
( ?oncentrations in Biota
Fathead minnows were removed and analyzed at several intervals during the seven day
study, and data for total ~4 C analysis of tissue (on a wet weight basis). Concentrations of ~4C
residues in fish removed from the tralomethrin spray drift microcosm vessel were 374 ± 124
~tg/kg on day four, and 312 ± 62/ag/kg on day seven. Bioconcentration factors (BCF) were
calculated by dividing these tissue concentrations by the water concentrations at the same
respective intervals. Bioconcentration factors determined in this manner were 219X for day
four and 315X for day seven. It should be noted, however, that the BCFs were not generated
under constant exposure conditions and may not represent steady-state values.
Extraction and analysis by HPLC of extra fish tissue removed on day four revealed that
14C tissue residues were largely metabolized in the fathead minnows removed from the
tralomethrin spray drift microcosm (Tables 6 through 9). The tissue contained 21.4 lxg/kg Stralomethrin, < 0.1 p,g/kg R-tralomethrin, 1.11 p.g/kg cis-deltamethrin, 32.7 lag/kg a-Rdeltamethrin, 63.1 tag/kg trans-deltamethrin and 14.3 ~tg/kg Br2CA. Mass balance, calculated
for the extraction and analysis of this tissue sample was 90.4%, with 83.6% removed in the
extraction process and 6.4% non-extractable from the tissue.
The bioconcentmtion factor
determined for the tralomethrin spray drift can be adjusted for the compound specific analysis of
tissue removed at hour 96. The tissue removed on day four contained 21.4 ~g/kg tralomethrin,
with a corresponding water concentration of 18.4 ng/L traiomethrin. The BCF determined in this
manner is 1200X, slightly higher than that determined using total ~4C residue concentrations.
In comparison, concentrations of ~4C residues in fish removed from the tralomethrin
runoff microcosm vessel were 15.4 :~ 4.0 p.g/kg on day four, and 13.4 ± 4.7/ag&g on day seven.
Bioconcentration factors (BCF) calculated by dividing these tissue concentrations by the water
concentrations at the same respective intervals were determined to be 185X for day four and
143X for day seven.
Extraction and analysis by HPLC of extra fish tissue removed on day four revealed that
14C tissue residues were largely metabolized in the fathead minnows removed from the
tralomethrin field runoff microcosm. The tissue contained 0.875 ~tg/kg S-tralomethrin, < 0.1
1759
Table 6. Total "C tissue concentrations for fathead minnows removed from the
tralomethrin spray drift mierocosm vessel, based on the specifie activity of tralomethrin
Sampling
Interval
(hours)
Pretreatment
0.5
1
Total 14C
Concentration
(~g/kg)
< 0.505
< 0.563
< 0.365
< 0.717
< 1.10
22.3
28.2
13.6
20.2
32.7
41.2
93.2
41.4
34.2
66.0
8
NS
24
162
22O
308
206
287
168
< 0.650
n = 5
NS
22.1
14.3
46.9
33.5
49.4
96
Average
(#g/kg)
465
285
223
373
523
217
296
380
313
352
23.4
n = 5
33.2
n = 5
55.2
n =5
NS
233
r~--5
374
n = 5
312
n=5
NS - Not scheduled to be sampled.
NOTE - The detection limit for each fish is dependent upon the counting efficiency and the
weight of the fish. Due to differences in these values, the detection limits vary among
fish.
1760
Table 7. Total ~4C tissue concentrations for fathead minnows removed from the
deltamethrin spray drift microcosm vessel, based on the specific activity of deltamethrin
Sampling
Interval
(hours)
Pretreatment
Total 14C
Concentration
(~g/kg)
<
<
<
<
<
0.617
0.437
0,241
0,353
0.584
0.5
NS
1
34.1
29,8
36.7
30,4
15.6
71.3
74.3
58.2
57.9
77.2
56.3
57.5
70.6
80.0
73.9
8
NS
24
186
172
207
200
207
96
Average
O~g/Icg)
< 0.446
n = 5
NS
29.3
n = 5
67.8
n = 5
67.7
n = 5
NS
194
n =5
148
106
152
200
161
n=5
199
168
130
132
122
127
134
129
n = 5
NS - Not scheduled to be sampled.
NOTE - The detection limit for each fish is dependent upon the counting efficiency and the
weight of the fish. Due to differences in these values, the detection limits vary among
fish.
1761
Table 8. Total 14C tissue concentrations for fathead minnows removed from the
tralomethrin runoff microcosm vessel, based on the specific activity of tralomethrin
Sampling
Interval
(houra)
Pretreatment
Total 14C
Concentration
~g/kg)
1.37=
2.20"
0.803`=
0.963"
0.990"
0.5
NS
1
1.81
0.417
1.69
1.30
2.55
2.10
1.07
1.08
4.91
0.803
1.37
1.63
2.68
2.33
4.56
8
NS
24
19.7
7.81
23.7
18.7
20.8
96
168
10.3
13.1
17.3
15.7
20.7
15.0
14.1
19.7
7.14
11.0
Average
(.ug/kg)
1.27
n=5
NS
1.55
n=5
1.99
n = 5
2.51
n = 5
NS
18.1
n=5
15.4
n = 5
13.4
n = 5
NS - Not scheduled to be sampled.
NOTE - The detection limit for each fish is dependent upon the counting efficiency and the
weight of the fish. Due to differences in these values, the detection limits vary among
fish.
" - Control contamination is suspected to have occurred during sample handling. The
contamination is insignificant compared to the number of dpm measured in the treatment
samples.
1762
Table 9. Total ~4C tissue concentrations for fathead minnows removed from the
deltamethrin runoff microcosm vessel, based on the specific activity of deltamethrin
Sampling
Interval
(hours)
Pretreatment
Total 14C
Concentration
(.u.g/kg)
Aversge
(p.g/kg)
0.394"
0.633 =
0.538 =
0.620 =
0.277"
0.492
n=5
0.5
NS
NS
1
1.14
1.09
0.981
0.898
1.28
1.43
1.43
1.06
0.999
1.65
3.89
3.43
3.94
3.95
4.89
8
24
NS
12.5
10.5
10.3
11.3
27.5
16.5
12.3
16.1
15.7
18.8
168
13.4
14.1
13.9
17.2
18.8
1.08
n = 5
1.31
n = 5
4.02
n = 5
NS
14.4
n = 5
15.9
n = 5
15.5
n = 5
NS - Not scheduled to be sampled.
NOTE - The detection limit for each fish is dependent upon the counting efficiency and the
weight of the fish. Due to differences in these values, the detection limits vary among
fish.
= - Control contamination, is suspected to have occurred during sample handling. The
contamination is insignificant compared to the number of dpm measured in the treatment
samples.
1763
~tg/kg R-tralomethrin, 3.31 Bg/kg deltamethrin, 0.940 ~tg/kg o~-R-deltamethrin, < 0.1 p.g/kg
trans-deltamethrin and 0.123 Bg/kg Br2CA. Mass balance, calculated for the extraction and
analysis of this tissue sample was g8.9%, with 77.4% removed in the extraction process and
10.7% non-extractable f~om the tissue.
Concentrations of 14C residues in fish removed from the deltamethrin spray drift
microcosm vessel were 161 ± 40 pg/kg on day four, and 129 ± 5 p.g/kg on day seven.
Bioconcentration factors (BCF) were calculated by dividing these tissue concentrations by the
water concentrations at the same respective intervals. Bioconcentration factors determined in
this manner were 26OX for day four and 185X for day seven.
Extraction and analysis by HPLC of extra fish tissue removed on day four revealed that
14C tissue residues were largely metabolized in the fathead minnows removed from the
deltamethrin microcosm vessel. The tissue contained 69.1 Bg/kg deltamethrin, 19.5 ~tg/kg ~-R
deltamethrin, 40.4 p.g/kg trans-deltamethrin and 7.16 ~tg/kg Br2CA.
Mass
balance, calculated for the extraction and analysis of this tissue sample was 91.9%, with 78.6%
removed in the back extraction process, and
12.1% nonextractable from the tissue.
The
bioconcentration factor determined for the deltamethrin spray drift can be adjusted for the
compound specific analysis of tissue removed at hour 96. The tissue removed on day four
contained 69.1 ~tg/kg deltamethrin, with a corresponding water concentration of 43.3 ng/L
deltamethrin. The BCF determined in this manner is 1600X, higher than that determined using
total 14C residue concentrations.
In the field runoff microcosm, concentrations of 14C residues in fish removed from the
deltamethrin microcosm vessel were 15.9 ± 2.3 ttg/kg on day four, and 15.5 ± 2.4 Bg/kg on day
seven. Bioconcentration factors (BCF) were calculated by dividing these tissue concentrations
by the water concentrations at the same respective intervals.
Bioconcentration factors
determined in this manner were 169X for day four and 166X for day seven.
Extraction and analysis by HPLC of extra fish tissue removed on day four revealed that
14C tissue residues were also largely metabolized in the fathead minnows removed from the
deltamethrin microcosm vessels. The tissue contained 2.82 i~g/kg deltamethrin, 3.59 ktg/kg ct-R
deitamethrin, 1.37 ILtg/kgtrans-deltamethrin and 0.108 ~tg/kg Br2CA. Mass balance, calculated
for the extraction and analysis of this tissue sample was 89.1%, with 58.0% removed from the
tissue in the hexane extract, 14.3% removed in the back extraction from acetone (aqueous)
1764
extract, 0.2% not able to be back extracted from the acetone (aqueous) extract and 16.5%
nonextractable from the tissue. The bioconcentration factor determined for the deltamethrin field
runoff can be adjusted for the compound specific analysis of tissue removed at hour 96. The
tissue removed on day four contained 2.82 ~tg/kg deltamethrin, with a corresponding water
concentration of 14.7 ng/L deltamethrin. The BCF determined in this manner is 192X, similar to
that determined using total 14C residue concentrations. Figure 5 presents the distribution of
metabolites extracted from fathead minnow tissues at 168 hours comparing tralomethrin and
deltamethrin under spray drift and field runoffconditions.
During the course of this study, 1.24%, 0.86%, 0.23% and 0.3 t% of total 14-C material
was removed by fish in the tralomethrin spray drift, deltamethrin spray drift, tralomethrin field
runoff and deitamethrin runofftreatments, respectively (Table 1).
Macrophytes were collected at pretreatment and days one, four and seven after application.
Total 14 C plant tissue concentrations are compared for tralomethri and deltamethrin under spray
drift and field runoff conditions in Table 10. On a dry weight basis, concentrations of 11.1
mg/kg, 14.2 mg/kg and 17.9 mg/kg were obtained for days one, four and seven, respectively in
the tralomethrin spray drift microcosm, whereas, concentrations of 1.42 mg/kg, 1.24 mg/kg and
0.779 mg/kg were obtained for days one, four and seven, respectively in the tralomethrin field
runoff microcosm. In the spray drift microcosm, concentrations appeared to increase with time,
whereas in the field runoff microcosm, concentrations in macrophytes did not appear to increase
with time. Based upon dry weights and the total 14C water concentrations, accumulation factors
were calculated for day seven to be 18,200X. and 8,290X, for spray drift and field runoff
treatments, respectively.
In comparison, on a dry-weight basis, concentrations of 7.03 mg/kg, 12.7 mg/kg and 8.69
mg/kg were obtained for days one, four and seven, respectively in the deltamethrin spray drift
microcosm, whereas, concentrations of 1.02 mg/kg, 1.05 mg/kg and 1.01 mg/kg were obtained
for days one, four and seven, respectively in the tralomethrin field runoff microcosm. Based
upon dry weights and the total 14C water concentrations, accumulation factors were calculated
for day seven to be 12,400X. and 10,700X, for spray drift and field runoff treatments,
respectively.
This data indicates that plant tissue present in aquatic systems significantly removes
pyrethroids from the water column.
During the course of this study, 1.5%, 1.7%, 0.53% and
1765
Figure 5. Plot of the composition of the 14C residues in the fish tissue at 168 hours comparing
tralomethrin and deltamethrin under spray drift and field runoffconditions.
1 O0
9O
~
80
~
7o
.2
60
~
50
,~
~" ~,o
~-.
~
30
~
m
20
~:
~0
I
0
Tralo
Spray
Drift
~
~
~
~
m
im
Delta
Spray
Drilt
Tralornethrin
Del~ame~hrm
a-R-Deltemethrin
trans-DeRamethrin
BrzCA
Tralo
Field
Runoff
De'Ita
Field
Runoff
1766
Table I0. Total 14 C plant tissue concentrations
(pg/kg) for tralomethrin and
deltamethrin under spray drift and field runoff condition~, based on their respective
specific activities
Sampling
Tmlomethrin
Deltamethrin
Tmlomethrin
Deltamethrin
Interval (hr)
Spray Dri~
Spray Drit~
Field Runoff
Field Runoff
Pretreatment
15.1
<3.85
19.5
8.26
24
II100
7030
1420
1020
96
14200
12700
1240
1050
168
17900
8690
779
I010
n.b. The detection limit for each sample is dependent upon the counting efficiency and the
weight of the sample. Due to difference in these values, the detection limit vary.
1767
0.52% of total 14-C material was removed by plants in the tralomethrin spray drift, deltamethrin
spray drift, tralomethrin field runoff and deltamethrin runoff treatments, respectively. It is
estimated that 9.08%, 5.85%, 1.24% and 2.12% of total 14-C material was remaining in plant
material at the end of the study, in the tralomethrin spray drift, deltamethrin spray drift,
tralomethrin field runoff and deltamethrin runoff treatments, respectively (Table 1).
Tralomethrin is rapidly converted to deltamethrin, with a half-life of 12.7 hours under
spray drift conditions and 6.8 hours under simulated runoff conditions, and then converted to less
active isomers and then to decamethrinic acid (BrzCA). After 24 hours, the percent radioactivity
of tralomethrin was 25% of the test material in the water column. This same degradation pattern
was observed for deltamethrin, as well. Concentrations of pyrethroids in water are also
dependent upon the mechanism of its addition to water.
Other researchers have measured
declining aqueous concentration of deltamethrin over time in pond environments [11,12]. The
rapid initial loss of pyrethroids in ponds is generally attributed to volatilization from the surface
water and sediment and plant adsorption. In this study, approximately 50-60% of the 14-C
material is unaccounted for and presumed to have volatilized.
Partitioning of pyrethroids among water, plants, sediment and fish is a function of the
method of introduction into the microcosm system. Spray drift applications of deltamethrin
yielded water concentrations that remained at or near the nominally applied dose (based on total
14C residue concentrations). The sediment was an important but not the primary sink for applied
pyrethroid under simulated spray drift application, however, approximately 30-40% of the 14-C
material was associated with sediment in the field runoff microcosms.
For tralomethrin,
concentrations in sediment reached a maximum concentration 96 hours after application and
decreased to approximately 30% of the maximum by 168 hours. Conversely, when deltamethrin
was applied simulating an agricultural runoff, water concentrations were lower, and the mass
dissolved in the water did not represent the major fraction of applied residues. Once associated
with sediment, pyrethroids tended to stay sorbed.
In sediment, tralomethrin was immediately converted to deltamethrin. Plant tissue was
found to significantly accumulate pyrethroids, with higher accumulation factors noted in spray
drift treatments.
Pyrethroid concentrations in fish are dependent on the method of introduction into the
microcosm and is related to aqueous concentrations.
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Acknowledgment
- This study was sponsored by Hoecht-Roussel Agri-Vet, Somerville, N.].
Than~" to the staff o f Springborn Laboratories, Inc..for their assistance.
REFERENCES
Aquatic Mesocosm Studies' in Ecological Risk Assessment.
Society of Environmental
Toxicology and Chemistry Special Publication (Edited by R.L. Graney, J.H. Kennedy
and J.H. Rodgers), Lewis Publishers, Boca Raton, FLorida (1994).
2.
J. L. Shaw and J.H. Kennedy, The use of aquatic field mesocosm studies in risk
assessment. Environ. Toxicol. Chem. 15:605-607 (1996).
Society of Environmental Toxicology and Chemistry. Workshop an aquatic microcosms
for ecological assessment of pesticides, Wintergreen, Virginia (Oct. 1992).
Microcosms in Ecological Research. (Edited by J.P. Giesy, Jr.), CONF-781101, U.S.
Department of Energy, Washington, D.C. (1980).
J. M. Giddings., R.L. Helm and F.J. deNoyelles. Large-scale microcosms as tools for
ecological assessments of pesticides. In Freshwater FieM Tests for Hazard Assessment
o f Chemicals (Edited by I.R. Hill, F. Heimbach, P. Leeuwangh and P. Matthiessen),
Lewis Publishers, Boca Raton, FL. (1994).
Freshwater Field Tests for Hazard Assessment o f Chemicals (Edited by I.R. Hill, F.
Heimbaeh, P. Leeuwangh and P. Matthiessen), Lewis Publishers, Boca Raton, Florida
(1994).
J.M Giddings, Microcosms for assessment of chemical effects on the properties of
aquatic ecosystems. In, Hazard Assessment o f Chemicals - Current Developments, Vol
II, pp. 45-94 (Edited by J. Saxena), Academic Press, New York (1983).
1769
8.
U.S. Environmental Protection Agency, Federal Insecticide, Fungicide and Rodenticide
Act. 40 CFR Part 160. U.S. Government Printing Office, Washington, D.C. (1989).
9.
L.W. Touart, Aquatic mesocosm tests to support pesticide registration, EPA 540/09-88035, Office of Pesticide Programs, U.S. Environmental Protection Agency, Washington,
D.C. (1988).
10.
J. M. Mao, K.M. Ersrfeld and P. H. Fackler, Simultaneous Determination of
Tralomethrin, Deltamethrin, and Related Compounds by I-1PLC with Radiometric
Detection, J. Agric. Food Chem. 41:596-601 (1993).
11.
D.C.G.Muir, G.P. Rown and N.P. Grift, Fate of the pyrethroid insecticide Deltamethrin in
Small Ponds: A mass balance study, J. Agric. l'))od (;hem. 33:603-609 (1985).
12.
R.J. Maguire, J.H. Carey, J.H. Hart, R.J. Tkacz and H. Lee, Persistence and fate of
Deltamethrin Sprayed on a Pond, d. Agric. FoodChem 37:1153-1159 (1989).