Microbial Versus Chemical Degradation of Atrazine in Soils1
- H. D. Skipper,
- C. M. Gilmour and
- W. R. Furtick2
Significance of microbial vs. chemical degradation of atrazine was determined using 14C-labeled atrazine and greenhouse incubation studies. Bacterial isolates evolved 0.4–0.7% of the input ethylamino chain-labeled atrazine as 14CO2 in 2 weeks, whereas, Aspergillus fumigatus respired 4.0% in sterile soil. No detectable 14CO2 was evolved from ring-labeled atrazine by any of the cultures tested. In nonsterile soils degradation of the hydroxyatrazine ring was 3-fold greater than for chloroatrazine in 2 weeks (1.5% vs. 0.5%). The native soil population respired 2.2–2.6% of chain-labeled atrazine in 4 weeks. Hydroxyatrazine accounted for approximately 20% of the extracted 14C-activity after 2–4 weeks incubation of 14C-atrazine in nonsterile or sterile soils. Greenhouse bioassay data showed a 73% loss of atrazine toxicity after 3–4 weeks incubation at 30C in nonsterile soil. These results support chemical hydrolysis of chloroatrazine to hydroxyatrazine as the major pathway of degradation in soils with microbial attack being of minor importance.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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