Degradation of Pesticides in Controlled Water-Soil Systems

Junk, Gregor A.; Richard, John J.; Dahm, Paul A.

doi:10.1021/bk-1984-0259.ch004

Cited by 9 publications

(11 citation statements)

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“…Other workers have demonstrated that high concentrations of atrazine and trifluralin did not degrade as readily as low concentrations [ 1,7,8] and the rate of leaching was greater at the higher concentrations [l]. In the study reported by Junk et al [7], alachlor and atrazine applied either alone or as mixtures with other pesticides at the rates of 15 and 300 mg/kg soil showed no degradation after 68 weeks in a controlled soil-water system.…”

Section: Effect Of Herbicide Concentration On Persistencementioning

confidence: 91%

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Microbial responses to large concentrations of herbicides in soil

Dzantor

Felsot

1991

Enviro Toxic and Chemistry

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To determine the effects of herbicide spills on microbial activity, soil was treated with excessive amounts (10,000 mg/kg) of formulated alachlor alone or as a mixture with formulated atrazine, metolachlor, and trifluralin. Soil was also treated with the same combinations of herbicides at a rate of 10 mg/kg, which is typical of normal farming practices. Simulated spills initially inhibited bacteria, but after 7 d, bacterial numbers had recovered to levels similar to those in untreated controls. Fungal populations were drastically reduced after 1 d and became undetectable after 7 and 21 d of incubation in the mixed herbicide and alachlor‐only treatments, respectively. Dehydrogenase activities were severely depressed after 1 d in both high‐level herbicide treatments and did not recover after 125 d. Esterase activities were depressed in soils receiving the mixture of herbicides but were generally unaffected in the alachlor‐only treatment. Normally applied concentrations did not have any pronounced effect on bacterial and fungal populations or on the activities of soil dehydrogenase and esterase. At 10 mg/kg, all the herbicides degraded by 80 to 90% within one year; there was no difference between degradation of alachlor applied alone or as a herbicide mixture. With high concentrations of herbicides, degradation was negligible after one year of incubation.

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Section: Effect Of Herbicide Concentration On Persistencementioning

confidence: 91%

“…Recently, attention has been focused on the degradation of high concentrations of pesticide mixtures commonly found at waste disposal sites [7,8,15]. Recently, attention has been focused on the degradation of high concentrations of pesticide mixtures commonly found at waste disposal sites [7,8,15].…”

mentioning

confidence: 99%

Microbial responses to large concentrations of herbicides in soil

Dzantor

Felsot

1991

Enviro Toxic and Chemistry

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“…Half-life estimates for atrazine range from 21 to 80 days (Winkelmann and Klaine, 1991;Smith and Walker, 1989); although Jones et al (1982) determined the half-life to be 330 and 385 days in two agricultural soils. Atrazine degradation is generally slower in the saturated environments Pang et al, 2005;Junk et al, 1984). Perry (1990) estimated the half-life for atrazine in a Kansas aquifer to be 1000 days.…”

Section: Introductionmentioning

confidence: 99%

“…In a saturated sandy loam, less than 10% of the added alachlor was degraded in 68 weeks (Junk et al, 1984). Novick et al (1986) reported that after 47 days incubation only 0.5% of the initial alachlor was mineralized in an aquifer material.…”

Section: Introductionmentioning

confidence: 99%

Persistence of Atrazine and Alachlor in Ground Water Aquifers and Soil

Schwab

Splichal

Banks

2006

Water Air Soil Pollut

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Degradation of atrazine and alachlor in saturated aquifer materials and soil was studied in the laboratory. A static aquifer was represented by a set of stagnant flasks and a well-mixed aquifer was simulated by recirculating columns. Water was tested at selected time intervals over six months and analyzed for herbicides and metabolites. Under all conditions, atrazine was more persistent than alachlor. Increased temperature had little effect on atrazine dissipation but did increase alachlor degradation rates, especially in the sterilized treatments. The addition of carbon and nitrogen prolonged the initial period before the onset of degradation in some of the columns. Enhanced mass transfer of the herbicides, nutrients, and oxygen in the recirculating columns dramatically increased dissipation of atrazine and alachlor. The degradation rates of atrazine and alachlor were 2 to 5 times faster in the recirculating columns than in the stagnant flasks. Atrazine was more persistent in the aquifer materials than in the soils, while alachlor dissipation was similar in the soils and recirculating aquifer columns, but was slower in the stagnant flasks. The prolonged persistence of atrazine under static, aquifer conditions (t 1/2 = 206 to 710 days) indicates that natural mechanisms are not sufficient to alleviate the risk of atrazine buildup over time; however, in a well mixed aquifer, atrazine degradation rates should be higher (t 1/2 = 66 to 106 days) and the threat of atrazine accumulation is diminished. Alachlor persistence at low concentrations (<10 μg L −1 ) in aquifers should not pose a long-term threat to ground water supplies.

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“…8 Several field studies have reported degradation of these and similar herbicides in agricultural fields, with half-lives ranging from days to months, depending upon environmental conditions. 16,17 Objectives The presence of exogenous secondary carbon sources and varying electron acceptor conditions can significantly affect the rate and extent of herbicide biotransformation. To better understand this relationship, a research project was initiated to investigate the effects of three inorganic electron acceptors (oxygen, nitrate, and sulfate) and two exogenous carbon sources (acetate and glucose) on the biotransformation of alachlor and propachlor.…”

Section: Discussionmentioning

confidence: 99%

Biotransformation of Herbicides in the Presence of Various Electron Acceptors

Wilber

Wang

1997

Journal of the Air & Waste Management Association

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Among the important factors affecting the biotransformation of xenobiotic chemicals upon their release into the environment are the dominant electron acceptor condition present and the presence of other, more readily degraded carbon sources. Here, glass-bead biofilm columns were used to investigate the effects of the presence of three different inorganic electron acceptor conditions (oxygen respiration, nitrate reduction, and sulfate reduction) on the biotransformation of the acetanilide herbicides alachlor and propachlor, and to determine the effects of two exogenous carbon sources (acetate and glucose) on their biotransformation under each of these conditions.Biotransformation of alachlor and propachlor occurred in the presence of both carbon sources and under each of the three electron acceptor conditions. Both were transformed most rapidly under sulfate-reducing conditions. Analysis by gas chromatography/mass spectrometry (GC/ MS) did not reveal any significant metabolic products. Both herbicides react abiotically with bisulfide, produced within the sulfate-reducing cultures, though most of the transformation was attributed to the microorganisms. The primary, readily degraded carbon source (acetate or glucose) was needed to establish each culture, and its continuous presence was required to sustain herbicide biotransformation in the sulfate-reducing reactors. Loss of either acetate or glucose from the column influent did not significantly affect herbicide biotransformation in the aerobic or nitratereducing reactors, at least for short periods. Temporary loss of the external electron acceptors (O 2 , NO 3 -, or SO 4 2-

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Degradation of Pesticides in Controlled Water-Soil Systems

Cited by 9 publications

References 0 publications

Microbial responses to large concentrations of herbicides in soil

Microbial responses to large concentrations of herbicides in soil

Persistence of Atrazine and Alachlor in Ground Water Aquifers and Soil

Biotransformation of Herbicides in the Presence of Various Electron Acceptors

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