Showing papers on "Microbial biodegradation published in 1971"

Microbial degradation of the herbicide atrazine and its 2-hydroxy analog in submerged soils

Abstract: the site of application to waters Soil-applied pesticides transported by erosion from and sediments are subject to conditions sufficiently different from those of aerated soils to alter pesticide persistence. Microbial degradation of '4C ring-labeled 2-choro--ethylamino-6-isopropylamino-s-triazine (atrazine) and Its 2-hydroxy analog (hydroxyatrazine) in submerged soils was studied by measurement of 'tCO. evolution and chromatographic se aration of metabolites in soil extracts. In 90 days, 1.67% of hydroxyatrazineC was evolved as ICO2, whereas only 0.005% of atrazine1C was recovered as 'ICO,.. With an energy source added to the soil, 3.8% of hydroxyatrazineIYC was recovered as JV CO, in 60 days. Chemi­ cal hydrolysis of atrazine to hydroxyatrazine is the principal pathway of detoxi­ cation in soil and is conducive to ring cleavage and total breakdown by microbes. Biological dealkylation without dehalogination occurs simultaneously; 2-chlor-4­ amino-6-isopropylamino-s-traizine was identified by TLC in the extracts from atrazine­ treated soil. Ring-labeled atrazine or hydroxyatrazine in soil did not evolve 4 COi. or 'YCHq4gas when the system was subjected to an anaerobic condition. Total breakdown of atrazine is expected to be slower in submerged sediments than In aerated soils because of the higher pH and restricted aeration of sediments.