Fate of Atrazine and Atrazine Degradates in Soils of Iowa

Kruger, Ellen L.; Coats, Joel R.

doi:10.1021/bk-1996-0630.ch012

Cited by 7 publications

(12 citation statements)

References 6 publications

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“…Conversely, DIA to parent compound ratios indicated that potentially a larger fraction of the atrazine was transformed to DIA at Oyster Landing and Oyster Creek, than was transformed to DEA at all sites. The DEA is considered to be the most commonly detected metabolite of atrazine [35], and was produced in greater concentrations in a sandy atrazine-contaminated agricultural soil in Wisconsin over 270 d [4] and in agricultural soil in Iowa after 60 d [36]. But relative concentrations of these metabolites may change in situ, as was reported over a two-year period by Panshin et al [37].…”

Section: Discussionmentioning

confidence: 92%

“…Kucklick and Bidleman [39] detected low levels of atrazine (1-104 ng/L) in the surface waters of North Inlet estuary, suggesting that atmospheric, groundwater, or surfacewater transport of these chemicals from upland sources may have occurred, but they did not measure atrazine degradation products. Kruger and Coats [36] determined that DEA was more mobile than atrazine in Iowan agricultural soils.…”

Section: Discussionmentioning

confidence: 99%

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Atrazine biodegradation to deisopropylatrazine and deethylatrazine in coastal sediments of different land uses

Aelion

Mathur

2001

Enviro Toxic and Chemistry

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Atrazine, a triazine herbicide widely used in the United States, contributes to surface-water and groundwater contamination, as can deisopropylatrazine (DIA) and deethylatrazine (DEA), two of its microbial degradation products. Production of DIA and DEA by native bacteria in aquatic sediments has not been investigated thoroughly. We assessed atrazine and production of DIA and DEA over time in coastal aquatic sediments associated with different land uses including creeks from an undeveloped preserve and a suburban development, a golf course drainage ditch, and a contaminated commercial harbor. Sediments were incubated in microcosms, spiked with U-14C-atrazine, extracted, and analyzed for 14C in a liquid scintillation counter. Atrazine, DIA, and DEA also were quantified by gas chromatography-mass spectrometry. The amount of 14C recovered varied at each site as a function of the sediment organic carbon content and decreased significantly over time. Both DEA and DIA were measured primarily in the aqueous phase. Transformation was more extensive to DIA than to DEA. The ratio of DIA to atrazine recovered from the undeveloped preserve was as high as 0.13. In contrast, the golf course had limited biotransformation, and had the greatest atrazine recoveries so atrazine, not DEA and DIA, may have a greater impact at this site.

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Section: Discussionmentioning

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Atrazine biodegradation to deisopropylatrazine and deethylatrazine in coastal sediments of different land uses

Aelion

Mathur

2001

Enviro Toxic and Chemistry

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“…Once applied, atrazine has an estimated half‐life of 24 to 128 d in soil, depending on soil characteristics, moisture, temperature, and depth [4,5]. Additionally, the half‐life of atrazine can be affected by microbial activity in the soil; microbes capable of degrading atrazine have been isolated [6,7], with some being capable of completely metabolizing the compound and its metabolites to CO 2 [8,9]. Atrazine and its metabolites also are somewhat mobile in soil.…”

Section: Introductionmentioning

confidence: 99%

Fate of atrazine in a grassed phytoremediation system

Henderson

Belden

Coats

2007

Enviro Toxic and Chemistry

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Atrazine is a well-known contaminant of surface waters and has been implicated in point-source pollution at agrochemical dealerships in the Midwest. Although the fate of atrazine has been well documented in soil and water, little is known about the fate of this contaminant and its metabolites within a grassed system. In the present study, [U-ring-14C]atrazine was added to soil in closed systems to determine the fate of the parent compound and its metabolites in soil, including degradation and movement into plants and air. Soil was treated with 25 mg/kg [14C]labeled atrazine and allowed to age for 5 d. Four systems then were amended with a mixture of prairie grasses, and the remaining four chambers were maintained as unvegetated controls. Dissipation and distribution of parent compound and metabolites were recorded for 21 d. Plant uptake of [14C]residue was less than 0.5% of applied radioactivity. Approximately 2% of total applied [14C]atrazine was mineralized to [14C]CO2, with no differences between vegetated and unvegetated systems. Mass balance recoveries were 76% for grassed systems and 77.5% for unvegetated controls. Approximately 40% of applied radioactivity remained bound to the soil following extraction. The most prevalent extractable compound detected in the soil was the parent, atrazine; major metabolites in soil were deethylatrazine (DEA) and didealkylatrazine (DDA). Leaf tissue contained concentrations of atrazine and key metabolites, i.e., DEA, DDA, and deisopropylatrazine (DIA), above those allowed in forage grasses by the U.S. Environmental Protection Agency; another key metabolite, hydroxyatrazine, was the most prevalent compound identified in both leaf and root tissue.

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“…However, more recent studies have identified abundant and active microbial populations in subsoils, indicating the potential for degradation 2–5. Degradation rates for a variety of pesticides in subsoil materials have been quantified in laboratory aerobic incubation studies 5–15. These studies show the potential for unsaturated zone degradation, but provide no evidence that the data generated reflect the actual potential of subsoil to degrade under real field conditions.…”

Section: Introductionmentioning

confidence: 99%

Quantification of acetochlor degradation in the unsaturated zone using two novel in situ field techniques: comparisons with laboratory‐generated data and implications for groundwater risk assessments

Mills

Hill

Newcombe

et al. 2001

Pest Management Science

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Degradation of the herbicide acetochlor in the unsaturated zone was quantified using two unique in situ field techniques. The DT50 values generated at two different sites on surface soil and two subsoil depths using these techniques were compared with values generated under aerobic laboratory-incubation conditions (typically 20 degrees C, 40% maximum water holding capacity). Additionally, laboratory-degradation data were generated on surface and subsoils from four other sites. All subsoils were treated with acetochlor at 5% of the surface soil application rate. Acetochlor degradation in both field- and laboratory-incubated subsoils was rapid and often exceeded surface soil rates. Field and laboratory DT50 values from all sites ranged from 2 to 88 days in subsoil, compared with a range of 1 to 18 days in surface soils. The DT50 results from in situ field techniques were comparable with those generated from laboratory incubations in the same soils, confirming the validity of performing laboratory-based degradation studies to determine pesticide DT50 values in subsoils. Microbiological characterisation of selected soils revealed that subsoils had a viable and active population, although direct counts of bacteria were consistently lower in subsoil (10(8)-10(9) g-1 dry soil) compared with surface soils (10(10) g-1 dry soil). The leaching models used to perform groundwater risk assessments (e.g. PELMO, PESTLA, MACRO-DB, PRZM and the FOCUS EU leaching scenarios) have provision for inclusion of subsoil degradation rates. However, conservative default estimates are typically used, as no other alternative is available. Results presented here show that these default values may significantly underestimate true subsoil degradation contributions, and therefore not accurately predict pesticide concentrations in groundwater. The degradation data generated for acetochlor were applied to the mathematical model PELMO to demonstrate the importance of the inclusion of subsoil degradation data in groundwater risk assessment models and thereby in the registration of pesticides in Europe.

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Fate of Atrazine and Atrazine Degradates in Soils of Iowa

Cited by 7 publications

References 6 publications

Atrazine biodegradation to deisopropylatrazine and deethylatrazine in coastal sediments of different land uses

Atrazine biodegradation to deisopropylatrazine and deethylatrazine in coastal sediments of different land uses

Fate of atrazine in a grassed phytoremediation system

Quantification of acetochlor degradation in the unsaturated zone using two novel in situ field techniques: comparisons with laboratory‐generated data and implications for groundwater risk assessments

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