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

Abstract

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.

Distribution of atrazine into three chemical fractions: Impact of sediment depth and organic carbon content

“…Microbial N-dealkylation of the ethyl and isopropyl side chains produces deethylatrazine and deisopropylatrazine, respectively [1,7], and microbial formation of hydroxyatrazine also has also been demonstrated [8][9][10]. Studies with native bacteria under natural conditions in coastal sediments and agricultural soils with little or no previous atrazine history have reported the mineralization of less than 1% of the total atrazine added [1,[14][15][16]. eralization of atrazine requires a bacterial consortium capable of using the triazine ring as a nitrogen source.…”

Analyzing transformation products of synthetic chemicals

“…An extensive body of literature has been published with respect to the quantitative analysis of TPs of pesticides in air [27,28], surface waters [29,30], groundwater [31,32], sediment [33,34], and soil [35,36] and several critical reviews on existing methods have been recently published [37,38]. A number of multiresidue methods have been developed for the determination of parent compounds and TPs covering a wide range of pesticide classes [37].…”

An Electrochemical Approach to Quantitative Analysis of Herbicides and to the Study of Their Interactions with Soils Components

“…The half-lives of herbicides vary from weeks to several months and, under environmental conditions, they are usually degraded to compounds with better water solubility. Indeed, the most important physicochemical properties of these pesticides and their degradations products are the solubility in water and the capacity to be retained by soils (Aelion & Mathur, 2001;Besse-Hogan et al, 2009). So that, the use of agricultural chemicals requires knowledge of their stability and transformation in the environment as well as their influence on micro-organisms.…”