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Fate of sprayed formulated aminocarb in freshwater
0045-6555/81/091025-I0~02.00/0
ChemosDhere, Vol.lO, No.9, pp 1025 - 1054, 1981 Printed in Great Britain
~)1981 Pergamon Press Ltd.
FATE OF SPRAYEDFORMULATEDAMINOCARB IN FRESHWATER J. K. Elner l, D. J. Wildish and D. W. Johnston l Fisheries and Environmental Sciences, Department of Fisheries and Oceans Biological Station, St. An6rews, New Brunswick, EOG 2XO, Canada
ABSTRACT Following simulated aerial spraying of Matacil(~)in field and tank experiments, the concentration of aminocarb increased in the subsurface water for some hour~ 22 h in the case of the field and 72 h for the tank. Thereafter, the concentration of MataciI,~)declined exponentially in subsurface waters. The equation for this, A = 4.834 + 0.165 g -.0.155T, can be used to predict the concentration of aminocarb in the lentic environment (A, ggL-i), providing the application rate (g ha-1) and time after application (T in h) are known. INTRODUCTION Forests in eastern Canada are sprayed aerially with pesticides to limit defoliation caused by the spruce budworm, Choristoneura fumiferana [1]. In 1978 the pesticide used in New Brunswick was the carbamate, aminocarb. Matacil(~)l.8D, contained 21.7% by weight of aminocarb, 51.2% of nonylphenol, and 27.1% of 585 oil [2]. In 1979 four ponds (three experimental, one control) in southwest New Brunswick were chosen to investigate possible side effects of Matacil(~)1.8D on lentic microorganisms [3]. The three treatment ponds were sprayed with Matacil(~)in the spring of 1980. The subsequent concentration of aminocarb was measured in the subsurface pond water. I n i t i a l l y less aminocarb than anticipated was found in the subsurface pond water; however, the concentration of aminocarb in the pond water increased over a 24-h period.
A tank study was initiated to investigate the
movement of formulated aminocarb through the surface microlayer and the subsurface water column. 1present address:
Fundy Isles Marine Enterprises, Ltd. P. O. Box 381, St. Andrews, N. B. EOG 2XO
Reprint requests to D. J. Wildish
1025
1026
METHODS i ) Field experiments The experimental ponds are described in Elner and Wildish [3].
Matacil®was sprayed
onto the ponds in a fine mist from a Solo 423 knapsack sprayer [4] to produce different concentrations in each pond. The equivalent application rates were: Pond B: 140 g a . i . ha- I , PoC: 700 g a . i . ha"1, Pond D: 280 g a . i . h a ' l ) . and remained as an emulsion during spraying.
The pesticide was mixed with 18 L of water Each application took place at 5:00 a.m. when the
a i r was cold and damp so as to minimize d r i f t of the pesticide.
I t was possible to spray the
entire surface area of each pond from the banks. Water samples for pesticide analysis were collected from a depth of approximately 0.2 m. Control samples of water from each pond were collected prior to pesticide application for aminocarb analysis. i i ) Tank experiment A glass tank (Fig. 1) was sunk to a depth of 0.44 m in a lawn. A system of 2 mm diameter glass tubing was constructed so that water samples could be withdrawn from fixed levels in the tank (Fig. 1).
The sampling tubes were f i t t e d with 250 um mesh f i l t e r s , to prevent blockages
due to particulate organic matter. The tank was f i l l e d with pond water collected from a fourth New Brunswick pond (Pond A). This water was l e f t to settle for 24 h.
Three control I-L samples of pond water were retained. i
An area of 2 m2 around the tank was sprayed with Matacil(~1.8D in a fine mist at a rate equivalent to 700 g a . i . ha"1,
To provide this concentration, 0.788 mL of Matacil(~
was emulsified with 3 L of deionized water. water surface.
I t is estimated that 6095 ~g aminocarb reached the
At the completion of this application the tank was f i l l e d to a depth of 0.38 m
with 26.8 L of pond water. Aminocarb in the surface microlayer was sampled by means of a GF/C f i l t e r held at the surface for 2 min, using procedures suggested by R. S. McGuire (personal communication). The f i l t e r s were immersed immediately in 10 mL of pesticide grade ethyl acetate and stored. Two samples, one from a constant depth of 0.2 m and a second from 0.01 m above the base of the tank, were removed during each sampling period.
These samples were drawn along the
appropriate glass tubes ( F i g . 1) by means of a m i l l i p o r e vacuum pump at a pressure of -5 mm Hg i n t o chemically clean sidearm f l a s k s . measurement of temperature and pH.
An additional 0 . 1 L o f each water sample allowed
1027
i••ltel-
i! Figure 1.
~ ~
30
To VOcUUm
cm AT
Diagram of the experimental tank system.
The tank was sampled eight times between the 19th and 25th August 1980 and a total of 16.5 L of water withdrawn.
At the end of the experiment the quantity of water remaining was
measured to determine losses due to evaporation over the study period.
No addition was made to
the tank due to rain. The tank walls were rinsed with ethyl acetate and the washings were analyzed for aminocarb to evaluate the amount of pesticide adsorbed onto the glass tank. iii)
Sampling and analysis of aminocarb Water samples (I L) for aminocarb analysis from both f i e l d and tank experiments were
collected in smoked-glass bottles.
Pesticide-grade ethyl acetate (15 mL) was added to each
sample to absorb the aminocarb. All samples were kept at 5°C in the dark until final extraction and analysis in the laboratories of the Research and Productivity Council, Fredericton, New Brunswick. Aminocarb was analysed following procedures described in Mallet [ 5 ] to a detection l i m i t (for 1L of water) of 0.5 ppb and with an average recovery of 95%. RESULTS i)
Field experiments
The control samples of water collected from each pond prior to pesticide application did not contain aminocarb. The post-spray concentrations of aminocarb in the subsurface water of Pond B declined exponentially from a value of between 20-30 ppb at 5 h to I ppb at 220 h
1028
(Fig. 2 ) .
The line in Fig. 2 is described by the equation, Ln aminocarb concentration = 3.05 -
0.0157T (R2 = 0.70); thus aminocarb in Pond B had a degradation rate constant of 0.057~ 0.0039 h-1. The aminocarb concentration in subsurface waters during the i n i t i a l 55-h period follows a polynominal curve with the equation C = 17.32 + 1.16T - 0.026T2 (R2 = 0.40) (Fig. 3). By differentiating this equation, i t can be determined that the maximum aminocarb concentration (30 ppb) at the O.2-m level in the water occurred 22.3 h after pesticide application.
a. 60 -
40
~
20 •
ee
,r---r E <¢
0
40
80
I
16'0
120
•
200
Time (h)
Figure 2.
Plot of aminocarb concentration vs time in the
subsurface water of pond B.
)
40
8g 20
e I
"~:
0
i
~ I
I0
i
l
20
m
I
I
30 Time (h)
I
40
i
I \1
50
°
I
60
Figure 3. Plot of ~ninocarbconcentrationin the subsurfacewater of Pond B during the initial55 h after pesticideapplication.
1o29
Post-application concentrations of aminocarb in the subsurface water of Ponds C and D are also recorded (Table I ) .
No attempt has been made here to compare these three sets of data to
investigate a dose effect. Table I.
Aminocarb concentrations at a depth of,~,O.2 m in Study Ponds C and D at timed intervals after Matacil~)application.
Time after spray
Pond
Aminocarb
(h)
(ppb)
2 48 120 168
20.8 31.3 N/D* 0.9
51 14g 388 436
27.3 24.3 2.3 1.1
*N/D - not detectable. i i ) Tank experiment The aminocarb concentration in the surface microlayer was reduced by 50% 23 h after pesticide application.
At 29 h, aminocarb was no longer detectable at the water surface (Table
II). Table I I .
Changes in aminocarb concentration in the surface microlayer.
Time after Matacil(~) application 0.2 23 29 50 72 120 144
Aminocarb coQcentration
(u g on"z) 0.22 0.11 0 0 0 0 0
Initially, aminocarb concentration in the subsurface water increased in value (Fig. 4). The subsequent overall decline in aminocarb concentration in the tank as a whole did not occur until 70.2 h after application {Fig. 4). When the top 0.2 m of water {estimated from the concentration at 0.2 m) are considered independently (Fig. 5), it will be noted that the
io3o
maximum pesticide concentration, as predicted by the regression line, is recorded at 64.4 h. The Matacil~)concentration in the lower section of the tank water column follows a pattern similar to that exhibited by the top 0,2 m of water, except the maximum aminocarb concentration occurs at 72.3 h (Fig. 6).
4000 3000
=o T=
2000
O
\
IOOO I
20
I
I
40
i
1
60
I
I
80
i
I
IO0
i
I
120
i
I
140
j
Time (h)
Figure 4.
Estimated total aminocarb in the tank water
column over the 6-day study period; the line follows the equation 2376,05 + 46.25T - 0.33T2 (R2 = 0.70).
2000 lo , / ~ , .o
Iooo o
o
zo
40
io
,o
Ioo
Io
Time (h)
Figure 5.
The quantity of aminocarb at 0.2 m in the
tank water column over the 6-day study period; the line follows the equation 1045.94 + 18.64T - 0.15T2
(R2 = 0.67).
lO31
,ooo o c
Iooo 210
i
i
40
I
so
i
I
eO
I
I
I
Ioo
i
J
12o
Time(h)
Figure 6.
The quantity of aminocarb in the lower section of the
tank water column over the 6-day study period; the line follows the equation 1359.18 + 27.64T - 0.19T2 (R2 = 0.60). Changes in pH and temperature of the tank water during the study (Table I l l ) were not sufficient to cause changes in degradation rates.
During the experiment, 2.93 L of water were
lost by evaporation and 1.8 ~g of aminocarb were removed from the walls of the tank by the end of the experiment. Table I I I .
pH and temperature of the water in the tank during the 6-day study period. Time after Matacil(~ application (h)
Temperature (°C)
pH
1. At 0.2m
0.2 4.0 23.0 29.0 50.0 72.0 120.0
15 12 11 18 15 15 15
6.9 6.8 6.9 6.8 6.8 6.9 6.9
2. 0.01 m from base of tank
0.2 4.0 23.0 29.0 50.0 72.0 120.0
15 12 11 17 15 15 15
6.9 6.7 6.8 6.6 6.8 6.9 6.9
3. Intermediate horizon in remaining water col~nn
144.0
12
6.9
1052
The relationship between the i n i t i a l concentration of aminocarb applied to the water surface and the concentration of aminocarb in the subsurface water at any given post-spray time is expressed by the following equation: A = 4.83 + 0.1615 g where:
0.155T
A = aminocarb concentration in the subsurface water in ~gl "1, g = aminocarb concentration sprayed onto the pond in g a . i . ha- I , T = time after spraying in h,
(S.E. of estimate = 48.8; R2 = 0.52). This equation was derived by multiple regression techniques, using data from the f i e l d and the tank experiments. DISCUSSION The aminocarb concentration in the subsurface water of Pond B declined exponentially over a period of 220 h, by which time i t had reached 1 ppb. This is similar to the behavior of fenitrothion in subsurface pond water [6]; however, fenitrothion, appears to degrade more rapidly.
At an application rate of 165 g ha- I , fenitrothion reached a maximum concentration
of 15 ppb at 0.67 h, declining to 0.1 ppb after 49 h.
Aminocarb increased in concentration in
the subsurface pond water for 22 h (Fig. 3), a time pattern not reported for fenitrothion. In the tank experiment Matacil(~was applied evenly at a rate equal to 700 g a . i . ha- I and, from t h i s , the quantity expected to f a l l on the surface of the water within the experimental tank was 6095 ug.
However, the actual aminocarb total in the tank at 0.2 h was
estimated at 3804 ug or 62.43% of that expected.
Estimateswere made of the pesticide in the
water column, the surface microlayer and on the glass tank walls.
The quantity of aminocarb
adhering to the glass was measured at the end of the experiment and may have varied s l i g h t l y from the amount at 0.2 h.
The highest total quantity occurring in the water column was 3996 ug
after 70 h; this figure accounts for 65.5% of that assumed to have been delivered, implying that early estimates are low.
The technique used for sampling aminocarb in the surface microlayer was inadequate, and thus the total aminocarb reaching the water surface may have been underestimated.
Minocarb
Continued to enter the subsurface water until 64.4 h after spraying, but the last detectable quantity of aminocarb in the f i l t e r was at 23 h (Table I I ) . Maguire and Hale [6] found fenitrothion to persist in the surface microlayer for at least 48 h after application. However, the thickness of the microlayer, estimated to be approximately 60 um [7], is defined operationally by the type of sampler used [8]. In the fenitrothion studies, sampling was with a glass plate [ 6 ] . Additional studies are required to understand the behavior of M a t a c i l ® i n
1033
the surface microlayer which is composed, in part, of a slick of organic matter [7] which has been shown to be important in the distribution of hydrophobic pollutants [6]. The aminocarb concentrations at 0.2 m in the subsurface water increased for approximatley 70 h after spraying in the tank experiment and for 22.3 h in the f i e l d experiment. The apparent transfer of ~ninocarb from the surface microlayer to the subsurface water was probably completed more rapidly in the pond, in part, due to mixing by wind action.
The tank was in a sheltered
area where the surface remained undisturbed. I f the aminocarb concentrations in the lower section of the tank are plotted against time, the following equation can be derived: C = 84.12 + 3.49T - 0.0235T2. This is now d i r e c t l y comparable with the polynomial curve derived from f i e l d data from Pond B (Fig. 3).
The slopes of these two lines are similar, i . e . 0.026 for the f i e l d data and 0.024
for the tank experiment.
This might be expected since, in each case, subsurface water at 0.2 m
below the surface was being sampled. As expected, aminocarb persisted longer in the lentic situation than previously described for l o t i c environments. G i l l i s [9] found a transitory peak of maximum 3 ppb after 12 h in some Nwe Brunswick streams following operational spray of 140 g a . i , ha-1. Zitko and McLeese [10] predict a kinetic profile for aminocarb in water after an aerial application of 140 9 a . i . ha- I .
Although their maximum values for post-spray aminocarb
concentrations in water are lov~r than those found in this study ( t h e i r maximum value bein9 below 1 ppb), their profile is essentially corroborated by this study.
The degradation rate
constant of 200 (yr -1) for ~ninocarb in water from their study [10] is comparable to that on a yearly basis in our study of Pond B which has a range of 69-205 based on the 95% confidence limit. ACKNOWLEDGMENTS We thank Flr, Hall et of the Maritime Forest Research Centre, Fredericton, for lending us the solo back-pack sprayer.
Work leading to this publication was funded, in part, by a USDA Forest
Service sponsored program entitled "Canada/United States Spruce Budwork Program," Grant No. 23-150, funding agency, North Eastern Forest Service. reviewed the manuscript.
Dr. D. W. McLesse and Mr. A. Sreedharan
Mr. P. W. G. McMullon prepared the figures, Mrs. J. Hurley and Ms. B.
McCullough typed the manuscript, and Ms. R. Garnett edited i t .
105~
REFERENCES i.
Anon., NRCC, 14140, 162 p. (1975).
2.
D. W. McLeese, V. Zitko, C. D. Metcalfe and D. B. Sergeant, Chenw)sphere,9_, 79-82 (1980).
3.
J. K. Elner and D. J. Wildish, Can. Tech. Rep. Fish. Aquat. Sci., 993, i i i + 21 p (1981).
4.
J. C. Boynton and C. C. Smith, Can. Forest. Serv. Info. Rel). M-X-24, 29 p. (1971).
5.
D. N. MaI]et (ed.), in "Proceedings from the symposium on aminocarb. Effects of its use on environmental quality," University of Moncton, N. B., 31-47 (1978)
6.
R. S. Maguire and E. J. Hale, J. A~ric. Food. Chem., 2_88, 372-378 (1980).
7.
G. W. Harvey, Limnol. Oceanogr., 1._]_1,608-613 (1966).
8.
R. S. Maguire, R. S., Intern. J. Environ. Anal. Chem., _7, 253-255 (1980).
9.
G. F. Gi]]is, Assesment of the effects of insecticide contamination in streams on the behavior and growth of fish, 1979. In "Environmenta] surveillance in New Brunswick 1978-1979," I. W. Darty, Ed., University of New Brunswick (1979).
10.
V. Zitko and D. W. McLeese, Can. Tech. Rep. Fish. Aquat. Sci., 985, i i i + 21 p. (1980). (Received in The Netherlands 27 July 1981)
ChemosDhere, Vol.lO, No.9, pp 1025 - 1054, 1981 Printed in Great Britain
~)1981 Pergamon Press Ltd.
FATE OF SPRAYEDFORMULATEDAMINOCARB IN FRESHWATER J. K. Elner l, D. J. Wildish and D. W. Johnston l Fisheries and Environmental Sciences, Department of Fisheries and Oceans Biological Station, St. An6rews, New Brunswick, EOG 2XO, Canada
ABSTRACT Following simulated aerial spraying of Matacil(~)in field and tank experiments, the concentration of aminocarb increased in the subsurface water for some hour~ 22 h in the case of the field and 72 h for the tank. Thereafter, the concentration of MataciI,~)declined exponentially in subsurface waters. The equation for this, A = 4.834 + 0.165 g -.0.155T, can be used to predict the concentration of aminocarb in the lentic environment (A, ggL-i), providing the application rate (g ha-1) and time after application (T in h) are known. INTRODUCTION Forests in eastern Canada are sprayed aerially with pesticides to limit defoliation caused by the spruce budworm, Choristoneura fumiferana [1]. In 1978 the pesticide used in New Brunswick was the carbamate, aminocarb. Matacil(~)l.8D, contained 21.7% by weight of aminocarb, 51.2% of nonylphenol, and 27.1% of 585 oil [2]. In 1979 four ponds (three experimental, one control) in southwest New Brunswick were chosen to investigate possible side effects of Matacil(~)1.8D on lentic microorganisms [3]. The three treatment ponds were sprayed with Matacil(~)in the spring of 1980. The subsequent concentration of aminocarb was measured in the subsurface pond water. I n i t i a l l y less aminocarb than anticipated was found in the subsurface pond water; however, the concentration of aminocarb in the pond water increased over a 24-h period.
A tank study was initiated to investigate the
movement of formulated aminocarb through the surface microlayer and the subsurface water column. 1present address:
Fundy Isles Marine Enterprises, Ltd. P. O. Box 381, St. Andrews, N. B. EOG 2XO
Reprint requests to D. J. Wildish
1025
1026
METHODS i ) Field experiments The experimental ponds are described in Elner and Wildish [3].
Matacil®was sprayed
onto the ponds in a fine mist from a Solo 423 knapsack sprayer [4] to produce different concentrations in each pond. The equivalent application rates were: Pond B: 140 g a . i . ha- I , PoC: 700 g a . i . ha"1, Pond D: 280 g a . i . h a ' l ) . and remained as an emulsion during spraying.
The pesticide was mixed with 18 L of water Each application took place at 5:00 a.m. when the
a i r was cold and damp so as to minimize d r i f t of the pesticide.
I t was possible to spray the
entire surface area of each pond from the banks. Water samples for pesticide analysis were collected from a depth of approximately 0.2 m. Control samples of water from each pond were collected prior to pesticide application for aminocarb analysis. i i ) Tank experiment A glass tank (Fig. 1) was sunk to a depth of 0.44 m in a lawn. A system of 2 mm diameter glass tubing was constructed so that water samples could be withdrawn from fixed levels in the tank (Fig. 1).
The sampling tubes were f i t t e d with 250 um mesh f i l t e r s , to prevent blockages
due to particulate organic matter. The tank was f i l l e d with pond water collected from a fourth New Brunswick pond (Pond A). This water was l e f t to settle for 24 h.
Three control I-L samples of pond water were retained. i
An area of 2 m2 around the tank was sprayed with Matacil(~1.8D in a fine mist at a rate equivalent to 700 g a . i . ha"1,
To provide this concentration, 0.788 mL of Matacil(~
was emulsified with 3 L of deionized water. water surface.
I t is estimated that 6095 ~g aminocarb reached the
At the completion of this application the tank was f i l l e d to a depth of 0.38 m
with 26.8 L of pond water. Aminocarb in the surface microlayer was sampled by means of a GF/C f i l t e r held at the surface for 2 min, using procedures suggested by R. S. McGuire (personal communication). The f i l t e r s were immersed immediately in 10 mL of pesticide grade ethyl acetate and stored. Two samples, one from a constant depth of 0.2 m and a second from 0.01 m above the base of the tank, were removed during each sampling period.
These samples were drawn along the
appropriate glass tubes ( F i g . 1) by means of a m i l l i p o r e vacuum pump at a pressure of -5 mm Hg i n t o chemically clean sidearm f l a s k s . measurement of temperature and pH.
An additional 0 . 1 L o f each water sample allowed
1027
i••ltel-
i! Figure 1.
~ ~
30
To VOcUUm
cm AT
Diagram of the experimental tank system.
The tank was sampled eight times between the 19th and 25th August 1980 and a total of 16.5 L of water withdrawn.
At the end of the experiment the quantity of water remaining was
measured to determine losses due to evaporation over the study period.
No addition was made to
the tank due to rain. The tank walls were rinsed with ethyl acetate and the washings were analyzed for aminocarb to evaluate the amount of pesticide adsorbed onto the glass tank. iii)
Sampling and analysis of aminocarb Water samples (I L) for aminocarb analysis from both f i e l d and tank experiments were
collected in smoked-glass bottles.
Pesticide-grade ethyl acetate (15 mL) was added to each
sample to absorb the aminocarb. All samples were kept at 5°C in the dark until final extraction and analysis in the laboratories of the Research and Productivity Council, Fredericton, New Brunswick. Aminocarb was analysed following procedures described in Mallet [ 5 ] to a detection l i m i t (for 1L of water) of 0.5 ppb and with an average recovery of 95%. RESULTS i)
Field experiments
The control samples of water collected from each pond prior to pesticide application did not contain aminocarb. The post-spray concentrations of aminocarb in the subsurface water of Pond B declined exponentially from a value of between 20-30 ppb at 5 h to I ppb at 220 h
1028
(Fig. 2 ) .
The line in Fig. 2 is described by the equation, Ln aminocarb concentration = 3.05 -
0.0157T (R2 = 0.70); thus aminocarb in Pond B had a degradation rate constant of 0.057~ 0.0039 h-1. The aminocarb concentration in subsurface waters during the i n i t i a l 55-h period follows a polynominal curve with the equation C = 17.32 + 1.16T - 0.026T2 (R2 = 0.40) (Fig. 3). By differentiating this equation, i t can be determined that the maximum aminocarb concentration (30 ppb) at the O.2-m level in the water occurred 22.3 h after pesticide application.
a. 60 -
40
~
20 •
ee
,r---r E <¢
0
40
80
I
16'0
120
•
200
Time (h)
Figure 2.
Plot of aminocarb concentration vs time in the
subsurface water of pond B.
)
40
8g 20
e I
"~:
0
i
~ I
I0
i
l
20
m
I
I
30 Time (h)
I
40
i
I \1
50
°
I
60
Figure 3. Plot of ~ninocarbconcentrationin the subsurfacewater of Pond B during the initial55 h after pesticideapplication.
1o29
Post-application concentrations of aminocarb in the subsurface water of Ponds C and D are also recorded (Table I ) .
No attempt has been made here to compare these three sets of data to
investigate a dose effect. Table I.
Aminocarb concentrations at a depth of,~,O.2 m in Study Ponds C and D at timed intervals after Matacil~)application.
Time after spray
Pond
Aminocarb
(h)
(ppb)
2 48 120 168
20.8 31.3 N/D* 0.9
51 14g 388 436
27.3 24.3 2.3 1.1
*N/D - not detectable. i i ) Tank experiment The aminocarb concentration in the surface microlayer was reduced by 50% 23 h after pesticide application.
At 29 h, aminocarb was no longer detectable at the water surface (Table
II). Table I I .
Changes in aminocarb concentration in the surface microlayer.
Time after Matacil(~) application 0.2 23 29 50 72 120 144
Aminocarb coQcentration
(u g on"z) 0.22 0.11 0 0 0 0 0
Initially, aminocarb concentration in the subsurface water increased in value (Fig. 4). The subsequent overall decline in aminocarb concentration in the tank as a whole did not occur until 70.2 h after application {Fig. 4). When the top 0.2 m of water {estimated from the concentration at 0.2 m) are considered independently (Fig. 5), it will be noted that the
io3o
maximum pesticide concentration, as predicted by the regression line, is recorded at 64.4 h. The Matacil~)concentration in the lower section of the tank water column follows a pattern similar to that exhibited by the top 0,2 m of water, except the maximum aminocarb concentration occurs at 72.3 h (Fig. 6).
4000 3000
=o T=
2000
O
\
IOOO I
20
I
I
40
i
1
60
I
I
80
i
I
IO0
i
I
120
i
I
140
j
Time (h)
Figure 4.
Estimated total aminocarb in the tank water
column over the 6-day study period; the line follows the equation 2376,05 + 46.25T - 0.33T2 (R2 = 0.70).
2000 lo , / ~ , .o
Iooo o
o
zo
40
io
,o
Ioo
Io
Time (h)
Figure 5.
The quantity of aminocarb at 0.2 m in the
tank water column over the 6-day study period; the line follows the equation 1045.94 + 18.64T - 0.15T2
(R2 = 0.67).
lO31
,ooo o c
Iooo 210
i
i
40
I
so
i
I
eO
I
I
I
Ioo
i
J
12o
Time(h)
Figure 6.
The quantity of aminocarb in the lower section of the
tank water column over the 6-day study period; the line follows the equation 1359.18 + 27.64T - 0.19T2 (R2 = 0.60). Changes in pH and temperature of the tank water during the study (Table I l l ) were not sufficient to cause changes in degradation rates.
During the experiment, 2.93 L of water were
lost by evaporation and 1.8 ~g of aminocarb were removed from the walls of the tank by the end of the experiment. Table I I I .
pH and temperature of the water in the tank during the 6-day study period. Time after Matacil(~ application (h)
Temperature (°C)
pH
1. At 0.2m
0.2 4.0 23.0 29.0 50.0 72.0 120.0
15 12 11 18 15 15 15
6.9 6.8 6.9 6.8 6.8 6.9 6.9
2. 0.01 m from base of tank
0.2 4.0 23.0 29.0 50.0 72.0 120.0
15 12 11 17 15 15 15
6.9 6.7 6.8 6.6 6.8 6.9 6.9
3. Intermediate horizon in remaining water col~nn
144.0
12
6.9
1052
The relationship between the i n i t i a l concentration of aminocarb applied to the water surface and the concentration of aminocarb in the subsurface water at any given post-spray time is expressed by the following equation: A = 4.83 + 0.1615 g where:
0.155T
A = aminocarb concentration in the subsurface water in ~gl "1, g = aminocarb concentration sprayed onto the pond in g a . i . ha- I , T = time after spraying in h,
(S.E. of estimate = 48.8; R2 = 0.52). This equation was derived by multiple regression techniques, using data from the f i e l d and the tank experiments. DISCUSSION The aminocarb concentration in the subsurface water of Pond B declined exponentially over a period of 220 h, by which time i t had reached 1 ppb. This is similar to the behavior of fenitrothion in subsurface pond water [6]; however, fenitrothion, appears to degrade more rapidly.
At an application rate of 165 g ha- I , fenitrothion reached a maximum concentration
of 15 ppb at 0.67 h, declining to 0.1 ppb after 49 h.
Aminocarb increased in concentration in
the subsurface pond water for 22 h (Fig. 3), a time pattern not reported for fenitrothion. In the tank experiment Matacil(~was applied evenly at a rate equal to 700 g a . i . ha- I and, from t h i s , the quantity expected to f a l l on the surface of the water within the experimental tank was 6095 ug.
However, the actual aminocarb total in the tank at 0.2 h was
estimated at 3804 ug or 62.43% of that expected.
Estimateswere made of the pesticide in the
water column, the surface microlayer and on the glass tank walls.
The quantity of aminocarb
adhering to the glass was measured at the end of the experiment and may have varied s l i g h t l y from the amount at 0.2 h.
The highest total quantity occurring in the water column was 3996 ug
after 70 h; this figure accounts for 65.5% of that assumed to have been delivered, implying that early estimates are low.
The technique used for sampling aminocarb in the surface microlayer was inadequate, and thus the total aminocarb reaching the water surface may have been underestimated.
Minocarb
Continued to enter the subsurface water until 64.4 h after spraying, but the last detectable quantity of aminocarb in the f i l t e r was at 23 h (Table I I ) . Maguire and Hale [6] found fenitrothion to persist in the surface microlayer for at least 48 h after application. However, the thickness of the microlayer, estimated to be approximately 60 um [7], is defined operationally by the type of sampler used [8]. In the fenitrothion studies, sampling was with a glass plate [ 6 ] . Additional studies are required to understand the behavior of M a t a c i l ® i n
1033
the surface microlayer which is composed, in part, of a slick of organic matter [7] which has been shown to be important in the distribution of hydrophobic pollutants [6]. The aminocarb concentrations at 0.2 m in the subsurface water increased for approximatley 70 h after spraying in the tank experiment and for 22.3 h in the f i e l d experiment. The apparent transfer of ~ninocarb from the surface microlayer to the subsurface water was probably completed more rapidly in the pond, in part, due to mixing by wind action.
The tank was in a sheltered
area where the surface remained undisturbed. I f the aminocarb concentrations in the lower section of the tank are plotted against time, the following equation can be derived: C = 84.12 + 3.49T - 0.0235T2. This is now d i r e c t l y comparable with the polynomial curve derived from f i e l d data from Pond B (Fig. 3).
The slopes of these two lines are similar, i . e . 0.026 for the f i e l d data and 0.024
for the tank experiment.
This might be expected since, in each case, subsurface water at 0.2 m
below the surface was being sampled. As expected, aminocarb persisted longer in the lentic situation than previously described for l o t i c environments. G i l l i s [9] found a transitory peak of maximum 3 ppb after 12 h in some Nwe Brunswick streams following operational spray of 140 g a . i , ha-1. Zitko and McLeese [10] predict a kinetic profile for aminocarb in water after an aerial application of 140 9 a . i . ha- I .
Although their maximum values for post-spray aminocarb
concentrations in water are lov~r than those found in this study ( t h e i r maximum value bein9 below 1 ppb), their profile is essentially corroborated by this study.
The degradation rate
constant of 200 (yr -1) for ~ninocarb in water from their study [10] is comparable to that on a yearly basis in our study of Pond B which has a range of 69-205 based on the 95% confidence limit. ACKNOWLEDGMENTS We thank Flr, Hall et of the Maritime Forest Research Centre, Fredericton, for lending us the solo back-pack sprayer.
Work leading to this publication was funded, in part, by a USDA Forest
Service sponsored program entitled "Canada/United States Spruce Budwork Program," Grant No. 23-150, funding agency, North Eastern Forest Service. reviewed the manuscript.
Dr. D. W. McLesse and Mr. A. Sreedharan
Mr. P. W. G. McMullon prepared the figures, Mrs. J. Hurley and Ms. B.
McCullough typed the manuscript, and Ms. R. Garnett edited i t .
105~
REFERENCES i.
Anon., NRCC, 14140, 162 p. (1975).
2.
D. W. McLeese, V. Zitko, C. D. Metcalfe and D. B. Sergeant, Chenw)sphere,9_, 79-82 (1980).
3.
J. K. Elner and D. J. Wildish, Can. Tech. Rep. Fish. Aquat. Sci., 993, i i i + 21 p (1981).
4.
J. C. Boynton and C. C. Smith, Can. Forest. Serv. Info. Rel). M-X-24, 29 p. (1971).
5.
D. N. MaI]et (ed.), in "Proceedings from the symposium on aminocarb. Effects of its use on environmental quality," University of Moncton, N. B., 31-47 (1978)
6.
R. S. Maguire and E. J. Hale, J. A~ric. Food. Chem., 2_88, 372-378 (1980).
7.
G. W. Harvey, Limnol. Oceanogr., 1._]_1,608-613 (1966).
8.
R. S. Maguire, R. S., Intern. J. Environ. Anal. Chem., _7, 253-255 (1980).
9.
G. F. Gi]]is, Assesment of the effects of insecticide contamination in streams on the behavior and growth of fish, 1979. In "Environmenta] surveillance in New Brunswick 1978-1979," I. W. Darty, Ed., University of New Brunswick (1979).
10.
V. Zitko and D. W. McLeese, Can. Tech. Rep. Fish. Aquat. Sci., 985, i i i + 21 p. (1980). (Received in The Netherlands 27 July 1981)