Arch. Environm. Contain. Toxicol. 8, 345-353 (1979)

Archives of

Environmental Contamination and Toxicology

Distribution and Retention of Atrazine and Carbofuran in Farm Pond Ecosystems 1 Harold E. Klaassen 2 and Ahmed M. Kadoum 3 Division of Biologyand Department of Entomology,Kansas State University, Manhattan, Kansas 66506

Abstract. The distribution and retention of atrazine and carbofuran in farm ponds were examined after application of 0.3 ppm of atrazine [2-chloro-4(ethylamino)-6-(isopropylamino)-S-triazine] for two years and 0.025 ppm of carbofuran (2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate) the first year and 0.050 ppm for the second year. Samples of water, mud, and various biological components for the systems were collected periodically for residue analyses by gas chromatography. Soon after atrazine was applied, it was found in all physical and biological components. No biological magnification was observed. Carbofuran showed up only in the water and mud immediately after application; from then on it was absent from all components. No adverse effects from either pesticide were observed in the biological components. The trend in agriculture has been away from persistent pesticides that produce detrimental ecological side effects. For many years long-lived, organochlorine pesticides were used, and they persisted in the ecosystem. Many also exhibited biological accumulation and magnification with a chain of undesirable effects. N e w e r pesticides that have replaced older ones are less persistent; others are apparently less toxic to nontarget organisms. However, they may eventually get into aquatic ecosystems. There is little information on the distribution and persistence of most of such chemicals in aquatic ecosystems under field conditions. This study was to determine distribution and retention of atrazine [2-chloro-4(ethylamino)-6-(isopropylamino)-S-triazine] and carbofuran (2,3-dihydro-2,2dimethyl-7-benzofuranyl methylcarbamate) introduced into pond systems. Atrazine is a widely used pre-emergent and post-emergent herbicide used to control most annual broadleaf and grass weeds in corn and sorghum. Carbofuran is a carbamate insecticide commonly used to control corn root worms, boll 1 Supported in part by North Central Regional Project NC-96, Environmental implications of pesticide usage, and the Kansas Agricultural Experiment Station, Kansas State University, Manhattan, Kansas 66506. z Associate Professor of Biology. 3 Associate Professor of Entomology. 0090-4341/79/0008-0345 $01.80 9 1979 Springer-Verlag New York Inc.

346

H . E . Klaassen et al.

weevil, alfalfa weevil, and armyworm either as foliar treatment or incorporated at seeding. Little is known about the fate of these chemicals after they get into aquatic systems. Yu et al. (1974) studied the fate of carbofuran as well as cyanazine, a triazine herbicide (Yu, et al. 1975), in laboratory model ecosystems. We used a field setting.

Materials and Methods Description of Ponds The study was conducted in four farm ponds in pasture near Manhattan, K a n s a s (northeast Kansas). The ponds had been formed by excavating d a m s across small drainages. Watersheds of the ponds were grasslands grazed by cattle. The ponds were filled with runoff water, primarily for watering cattle. During 1973, the water volume in the ponds declined slightly during the year. In 1974 the ponds filled up with runoff in the spring before the treatment was begun, and t h e n the volume slowly declined through the rest of the year. Table 1 gives some physical and chemical characteristics of the ponds during the two years of our study. Absolute values given are of minor importance because they vary somewhat depending on time of sampling. The general magnitude of the values is meaningful, however, for characterizing the ponds. The ponds had established fish populations. Ponds I, III, and IV had bluegill (Lepomis machrochirus) only. Pond II started out with bluegills but was soon contaminated with green sunfish (Lepomis cyaneIlus) and later with black bullheads (Ictalurus melas).

Test Chemicals W e u s e d the herbicide atrazine and the insecticide carbofuran. The formulation of atrazine was AAtrex 4L | 43% active ingredient, produced by Ciba-Geigy Corporation. The formulation of carbofuran was Furadan 4 Flowable | 43.8% active ingredient, produced by Niagara Chemical Division of the F M C Corporation. The toxicities of the chemicals to fish were verified with bioassays. Static bioassays were conducted with fingerling bluegill and dechlorinated city water. T h e 96 hr LCs0 for atrazine w a s 15 p p m a n d for carbofuran 0.25 ppm.

Table 1. Physical and chemical characteristics of study ponds during the growing season (April through October) of the two years (1973-1974) of this study. On the ranges, the upper n u m b e r s are for surface water; lower numbers, for bottom water Average size

Pond Treatment I Atrazine II Carbofuran III Atrazine and Carbofuran IV Control

Area

Volume

Range

Turbidity JTU

1.20 acres 255,000 ft'~ 6-240 (0.49 ha) (7,221m3) 2-148 0.94 acres 110,000ft3 50-550 (0.38 ha) (3,115ma) 70-540 0.63 acres 80,000ft~ 10-110 (0.26 ha) (2,265m3) 12-100 1.38 acres 192,000ft3 27-550 (0.56 ha) (5,437m3) 27-550

Specific conductivity micromho/ cm 130-330 125-330 159-380 220-390 300-475 295-500 128-260 132-275

pH

Dissolved oxygen mg/L

CO2 Alkalinity mg/L mg/L

7.0--8.6 7.1-8.6 6.6-9.7 6.8-8.5 7.7-8.3 7.4-8.0 6.8-8.6 7.3-8.6

4.3-10.6 0.0-10.6 1.9-14.0 0.0-11.2 5.6-10.4 0.1- 9.2 5.1-10.4 0.8-10.0

0-8 0-42 0-24 0-29 0-13 7-22 0-12 0-14

75-153 69-168 48-144 63-147 121-210 132-228 54-120 60-129

Atrazine and Carbofuran in Farm Pond Ecosystems

347

The pesticides were applied in July to the ponds at rates low enough to avoid fish kills yet at rates that could be expected in ponds receiving runoff from treated fields (Kadoum and Mock 1978): carbofuran at 0.1 of the 96 hr LCs0 for bluegills (0.025 ppm) in 1973, and 0.2 of the LC~0 (0.050 ppm) in 1974; atrazine at 0.02 of the 96 hr LCso (0.30 ppm). One pond (I) received only atrazine, one pond (II) received only carbofuran, and one pond (III) received both chemicals at previously mentioned rates. One pond (IV) was the control. The pesticides were added by pouting the diluted material into the pond from a motor boat, then mixed by agitation with the boat's motor to assure even distribution.

Sampling The treated ponds were sampled one to six days before being treated, within three days after treatment, about three weeks after treatment, and twice more after that, ending ha mid-fall (exact intervals are given in the tables). At each sampling time we collected the following types of samples: 1.. Water: Two gallons of surface water were collected in glass containers. 2. Silt: Two silt samples were collected from each pond, one from the shallow peripheral area and one from the deep center of the pond. Silt was collected with an Ekman dredge from several sites. The surface one cm was scraped off and retained until a liter of silt was accumulated. 3. Zooplankton: Twenty g zooplankton was collected by making tows with a 20-mesh plankton net. 4. Crayfish: Crayfish were collected by seining. 5. Tadpoles: Bullfrog tadpoles were collected by seining. 6. Fish: Fish were collected by seining, and grouped into small, medium, and large sizes. For bluegill, small was less than 75 ram; medium, 76-150 ram; large, greater than 150 ram. For bullheads collected from pond II, small was less than 100 mm; medium, 101-200 ram; large, greater than 200 mm.

Water and silt were extracted immediately after collecting. Zooplankton was frozen in aluminum foil for later extraction. Crayfish, tadpoles, and the fish samples were cut into pieces and homogenized with known amounts of distilled water in a blender. The homogenate was frozen in aluminum foil for later extraction.

Extraction of Soil (Silt) Stones and other large objects were removed from the soil and the sample thoroughly mixed with a spatula on a sheet of alaminum foil. A 150 g portion of the water-saturated soil was weighed in a quart jar together with 100 ml acetone. The mixture was then shaken vigorously for five rain on a vertical and horizontal mechanical shaker. The slurry was extracted with three successive 100 ml portions of ethyl acetate. The total extract (acetone, ethyl acetate, and water) was decanted, and combined in a 1000-ml round bottom flask. The volume was measured accurately and calculated as an aliquot of the original volume. The combined extract was evaporated to dryness under vacuum and in a 45~ water bath. The residue was dissolved in 5 ml benzene for column chromatography.

Extraction of Water Water samples were collected in clean glass gallon jars and brought to the laboratory. Two L of each sample was placed in one-gal jars and extracted twice with 200 ml each of 50% (v/v) ethyl acetate in hexane. The gallon jar was shaken vigorously for at least one min during extraction. After the phases separated, the ethyl acetate-hexane (upper) layer was decanted into a one-liter, round-bottom flask. The water was then re-extracted with 400 ml chloroform which was combined with the ethyl acetatebexane extract and evaporated to dryness under vacuum in the 45~ water bath. The extract was dissolved in 5 ml benzene for column chromatography.

348

H.E. Klaassen et al.

Extraction ofFish and Zooplankton A 20-g sample of chopped tissues was weighed in a 400-ml omnimixer cup, and the tissue was blended in 150 ml of 50% ethyl acetate in hexane at high speed for one min and then filtered with suction through a 12-cm Buchner funnel into a 500-ml suction flask using #43 Whatman filter paper. The sample was washed with an additional 100 ml of 50% ethyl acetate in hexane. The combined filtrates were evaporated to dryness under vacuum in a 45~ water bath. The residue was dissolved in 5 ml benzene for column chromatography.

Cleanup Procedure A Kontes K420280 Chromallex column, 10.5 mm I.D., was packed with a mixture of 24 g Celite 545, 12 g MgO, and 15 g Norit SG 1 carbon and capped with a 5-mm glass wool plug. The column was prewashed with acetone. Elution was made with the aid of pressurized nitrogen. The extract in 5 ml benzene was added to the column and eluted with 75 ml of 25% (v/v) ethyl acetate in benzene with the solvent collected in a 250-ml, round-bottom flask. The column was flushed dry with nitrogen gas, and the eluate evaporated to dryness under vacuum in a 45~ water bath. The residue was then redissolved in benzene for injection in the gas chromatograph.

Gas Chromatographic Analysis The nitrogen compounds were separated on a dual column Tracor 550 gas chromatograph equipped with a Coulson conductivity detector set in the nitrogen mode. Both columns were 3 ft x I/4 in. I.D. (91 c m x 6 ram) Pyrex, packed with Chromosorb W HP, 70/80 mesh. One column used a 3% OV-25 liquid phase, the other a 1.1% Carbowax 20M. Hydrogen was the carrier gas at a flow rate of 58 ml/ rain. Temperatures for the inlets were 200~ outlets, 210~ transfer line, 215~ furnace valve block, 220~ The furnace was operated at 900~ Atrazine and carbofuran (retention times 680 and 1053 seconds, respectively) were separated on OV-25 at an oven temperature of 140~ and a carrier gas flow of 80 ml/min. The much larger atrazine peak was vented off before switching the column onto the detector to allow the carbofuran to be observed on the recorder without prior disturbance. Atrazine appeared at 197 seconds on the Carbowax column at an oven temperature of 140~ and carrier gas flow of 58 ml/min. Sensitivity of the detector to nitrogen compounds was 1.2 ng of N at a peak size equal to twice the baseline noise. An Autolab 6300 digital integrator was used to quantify the peak values. Preliminary results from recovery studies using pure standards of the tested pesticide yielded average recoveries of 98 -+ 3% for carbofuran and 103 _+ 2% for atrazine (Kadoum and Mock, 1978).

Results and Discussion T h e r e s u l t s o f t h e r e s i d u e a n a l y s e s a r e p r e s e n t e d f o r t h e p o n d s in T a b l e s 2 to 5. N o r e s i d u e s w e r e d e t e c t e d at a n y t i m e in a n y c o m p o n e n t o f t h e c o n t r o l p o n d . P o n d s I a n d I I I ( T a b l e s 2, 4 a n d 5), t r e a t e d w i t h a t r a z i n e , h a d n o a t r a z i n e r e s i d u e s b e f o r e t r e a t m e n t . S o o n a f t e r t r e a t m e n t r e s i d u e s w e r e f o u n d at h i g h l e v e l s ( 1 6 5 - 3 5 3 p p b ) in all c o m p o n e n t s e x c e p t t a d p o l e s . R e s i d u e s d e c r e a s e d s l i g h t l y d u r i n g t h e g r o w i n g s e a s o n , b u t w e r e still p r e s e n t at f a i r l y h i g h l e v e l s at t h e e n d o f t h e g r o w i n g s e a s o n . R e g r e s s i o n a n a l y s e s w e r e r u n o n t h e s e d a t a to d e t e r m i n e t h e r a t e o f d e c a y ( n e g a t i v e slope). T h e s l o p e a n d t h e R 2 v a l u e s are g i v e n in t h e t a b l e s . T h e s e v a l u e s s h o w t h e r a t e s o f l o s s o f r e s i d u e , b u t t h e l e v e l s of significance are unknown because of the low number of degrees of freedom. In

305 277

. 289 237 245

316 240

. . ND 280 270 290

ND ND . . ND ND ND ND

314

323

ND

230

22

309

1

ND b

0a

307 290 260

221 213 250

302

237

55

. 216 230 211

204 195 .

284

206

120

1.001 • .322 .535 • .304 . . . . .568 • .358 .222 • .349 .555 --- .214

.323 • .022

.676 • .367

.56 .17 .77

.83 .61

.99

.63

R2

.

6

1

ND ND --

4 ND

0a

. 289 286 241 --

292 219

311

269

2

321 217 . 278 269 222 258

303

263

23

Days after treatment Slope and std. dev.

Days after treatment

a Pre-treatment b N D = Not detectable (less than 0.4 ppb) c - Samples could not be obtained

Surface water Mud from shallow area Mud from deep area Zooplankton Clam Bullfrog tadpole Small bluegill Medium bluegill Large bluegill

Sample Type

1974

1973

309 218 230 --

295 233

278

252

51

235 201 214 --

278 185

247

270

85

.518 • .494 1.094 • 188 .257 • .135

.282 • .291 .345 • .316

.794 _+ .077

.009 • .180

Slope and std. dev.

.36 .94 .64

.32 .37

.98

.002

R2

Table 2. Atrazine residues (ppb) and rate of decay (negative regression slope) in Pond I during 1973 and 1974 at four different indicated times after application. Pond was treated at 0.3 ppm both summers

~0

O

t~

b

a

ND ND ND .

ND ND ND

ND ND ND b . ND ND ND

.

10.6

ND a

.

.

26

. .

50

.

85

. ND ND ND

ND ND

ND

ND

ND ND ND

.

ND ND

ND

ND

ND ND ND

ND ND

ND

ND

ND -ND ND

ND ND

ND

ND

Pretreatment

1

Pretreatment

N D = Not detectable (less than 0.4 ppb), - Sample could not be obtained.

Surface w a t e r Mud from shallow area M ud from deep area Zooplankton Small black bullhead Medium black bullhead Small bluegill Medium bluegill Large bluegill

Sample type

1974

1973

Days after t r e a t m e n t

ND -ND --

ND

46.2 ND

26.4

15.0

3

--ND --

ND

ND ND

ND

ND

25

-ND ND --

ND

ND ND

ND

ND

62

-ND ND ND

--

ND ND

ND

ND

95

Table 3, Carbofuran residue levels in ppb in Pond II during 1973 and 1974 at various t i me s after application. Pond w a s tr eated at 0.025 ppm in 1973 and at 0.050 in 1974

~Z

~, r

ND ND ND ND ND ND ND ND ND

ND

ND ND ND ND

ND ND ND ND

a N D = Not detectable (less than 0.4 ppb) b -- Sample could not be obtained

ND

ND a

Surface water Mud from shallow area M u d from deep area Zooplankton Small crayfish Large crayfish Bullfrog tadpoles Small bluegill Medium bluegill Large bluegill

Carb.

Atr.

Sample type

Pre-treatment

276 280 290 276

310 206 201 225

353

251

Atr.

3 days

ND ND ND ND

ND ND ND ND

44

5.4

Carb.

201 297 242 b

246 282 220 210

366

262

Atr.

21 days

ND ND ND .

ND ND ND ND

ND

ND

Carb.

.

.

207 220 212

228 165 185 t70

214

178

.

Atr.

77 days

ND ND ND

ND ND ND ND

ND

ND

Carb.

-+ .632 -+ 1,233 _+ .329 -+ .023 0.685 +_ .835 0.945 _+ .454 0.93l -+ ,417

0.921 0.920 0.314 0.736

2.077 +- .672

1.109 _+ .413

Slope and std. dev.

.40 .81 .83

.68 .36 .48 .99

.91

.87

R '2

Table 4. Residues (in ppb) of Atrazine (treated at 0.3 ppm) and rate of Atrazine decay (negative regression slope) and Carbofuran (treated at 0.025 ppm) in Pond III at indicated tinae intervals after both were applied together in 1973

t~

~~

g~

N

;>

ND

ND

ND ND __

ND ND ND ND ND

19

21 ND a b

ND ND ND ND ND

Carb.

2

Atr.

a N D = Not detectable (less than 0.4 ppb) b - Sample could not be obtained.

Surface water Mud from shallow area M u d from deep area Zooplankton Small crayfish Medium crayfish Large crayfish Bullfrog tadpole Small bluegill Medium bluegill

Sample type

Pre-treatment

281 201 227 283 246

287 275 __

251

256

Atr.

2 days

.

280 219 231

ND ND --

225 . 271 265

315

59.5

ND ND ND ND

282

33,5

NO

Atr.

Carb,

23 days

.

.

ND ND

ND

ND ND ND

ND

1.5

Carb.

.

.

201 . 265 253

235 217 226

232

278

Atr,

.

54 d a y s

. ND ND

ND

.

ND ND ND

ND

ND

Carb.

.

.

214 221

192

225 204 184

254

255

Atr.

92 days

ND ND

ND

ND ND ND

ND

ND

Carb.

,731 _+ .187 .332 -+-+.239

.199 -+ .211

.760 -+ .169 .661 +- .326

.289 -+ .617

.068 -+ .250

Slope and std. dev.

.88 .49

.30

,91 .67

.10

.04

R2

Table 5. Residues (in ppb) of Atrazine (treated at 0.3 ppm) and rate of Atrazine decay (negative regression slope) and Carbofm'an (treated at 0.050 ppm) in Pond III at indicated time intervals after both were applied together in 1974

g

Atrazine and Carbofuran in Farm Pond Ecosystems

353

the second year of the study, low residue levels (21 ppb or less) were found in the water and mud before second year treatments began; however, no pre-treatment residue was found in the biological components. The same pattern of decay followed the second treatment. No biological magnification was observed. Mauck, Mayer, and Holz (1976) found a similar pattern for simazine, a closely related compound: low levels of simazine persisted 456 days after treatment in the pond ecosystem, but there were no observable adverse effects on the bluegill. Our results are also similar to those of Yu et al. (1975) who studied another triazine herbicide, cyanazine, in a model aquatic ecosystem. They found the uptake in the biological components ranged from 1.3 ppm in algae to 0.05 ppm in fish. They also concluded that there was no concentration through the food chain. Ponds II and III (Tables 3, 4, and 5), treated with carbofuran, also showed no carbofuran residues before treatment. After treatment, residues were found only in the water and mud, and even in these materials only for a few days. During the second year, when the dose rate was doubled, residues were higher, but with the same pattern except for 1.5 ppb carbofuran in the water of pond III after 23 days (Table 5). No residues were found in any of the biological components of the pond systems. Carbofuran apparently breaks down rapidly in water. Our results are similar to those of Yu et al. (1974) who studied the fate of carbofuran in a model ecosystem. They found rapid degradation in water and no residues of the parent carbofuran in the living organisms. We observed no effect on organisms in the treated ponds. Zooplankton persisted in normal patterns. Fish reproduced and grew as usu~d. Nothing unusual was noted concerning other aquatic organisms, and there were no noticeable differences between the pond receiving both pesticides and those receiving either atrazine or carbofuran separately. Acknowledgment. We appreciate the as sistance of Mr. Herb Bollig in collecting many of the samples for residue analyses and Dr. Arthur D. Dayton for assisting in the regression analysis.

References Kadoum, A. M., and D. E. Mock: Herbicide and insecticide residues in tailwater pits: Water and pit bottom soil from irrigated corn and sorghum fields. J. Agric. Food Chem. 26, 45 (1978). Mauck, W. L., F. L. Mayer, Jr., and D. D. Holz: Simazine residue dynamics in small ponds. Bull. Environ. Contain. Toxicol. 16, 1 (1976). Yu, Ching-Chieh, G. M. Booth, D. J. Hansen, and J. R. Larsen: Fate of carbofuran in a model ecosystem. J. Agric. Food Chem. 22, 431 (1974). Yu, Ching-Chieh, G. M. Booth, and J. R. Larsen: Fate of triazine herbicide cyanazine in a model ecosystem. J. Agric. Food Chem. 23, 1014 (1975).

Manuscript received June 10, 1978, accepted August 14, 1978.

Distribution and retention of atrazine and carbofuran in farm pond ecosystems.

Arch. Environm. Contain. Toxicol. 8, 345-353 (1979) Archives of Environmental Contamination and Toxicology Distribution and Retention of Atrazine a...
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