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PHYSICAL AND CHEMICAL FACTORS THAT INFLUENCE THE ANAEROBIC DEGRADATION OF METHYL PARATHION IN SEDIMENT SYSTEMS
Citation:
Wolfe, N., B. Kitchens, D. Macalady, AND T. Grundl. PHYSICAL AND CHEMICAL FACTORS THAT INFLUENCE THE ANAEROBIC DEGRADATION OF METHYL PARATHION IN SEDIMENT SYSTEMS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-86/301 (NTIS PB87175659), 1986.
Description:
The kinetics of disappearance of methyl parathion (0,0-dimethyl-0-p-nitrophenyl phosphorothioate) were studied in anaerobic sediment samples in the laboratory as a function of methyl parathion concentration, pH, and Eh. The disappearance of methyl parathion is described by first-order kinetics and amino methyl parathion (0,0-dimethyl-0-p-aminophenyl phosphorothioate) was identified as a reduction product. In the strongly reducing sediments, the half-lives were on the order of a few minutes. In water isolated from the sediment, no reaction could be detected over the period of a week. Also, there is no apparent correlation between the first-order disappearance rate constants and the pH of the sediment samples. In heat-sterilized sediments, the disappearance rate constants are retarded about two orders of magnitude relative to nonsterile sediments. In chemically treated sediments, first-order disappearance rate constants are comparable to those in the nonsterile system. (Copyright (c) Pergamon Journals Ltd., 1986.)