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Abstract

 

This article in SSSAJ

  1. Vol. 43 No. 6, p. 1129-1134
     
    Received: Dec 26, 1978


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doi:10.2136/sssaj1979.03615995004300060013x

Atrazine Degradation and Residue Distribution in Soil1

  1. T. H. Dao2,
  2. T. L. Lavy3 and
  3. R. C. Sorensen4

Abstract

Abstract

Degradation and its effect on atrazine leaching were observed in soil in the laboratory. Degradation of 1.5 ppmw (wt/wt) of ring labeled 14C-atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) over time periods up to 8 months was predominantly a nonbiological process in three nonsterilized soils at 0.1 bar moisture content, although there was evidence that the atrazine molecule was dealkylated simultaneously. Between 4 and 17% of the applied 14C was present as nonpolar compounds after 1 month of incubation at 30°C. The amount of 14CO2 evolved was cumulatively less than 0.05% of the added radiocarbon at 5 and 30°C. Desorption of atrazine from soil treated and incubated for 0.5 hour; 1 and 2 weeks; 1, 2, 4, and 8 months showed a steady increase in the unextractable fraction remaining in soil with time. In the soil extract, a tolueneinsoluble fraction increased as time passed, and made up between 24 and 62% of the extracted radiolabeled fraction of the three soils after 1 month of incubation at 30°C. The ratio of polar compounds to nonpolar compounds steadily increased with time of incubation. Major possible metabolites of the toluene-soluble fraction were identified by thin layer chromatography as monodealkylated products. During elution of atrazine from soil columns saturated with water, decreasing the water flow rate from 2 cm/hour to 0.08 and 0.04 cm/hour greatly reduced the downward movement and enhanced degradation of the herbicide.

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