||Fate of Fenthion in Salt-Marsh Environments: 1. Factors Affecting Biotic and Abiotic Degradation Rates in Water and Sediment.
Cripe, C. R. ;
O'Neill, E. J. ;
Woods, M. E. ;
Gilliam, W. T. ;
Pritchard, P. H. ;
||Technical Applications, Inc., Arlington, VA. ;Georgia State Univ., Atlanta.;Environmental Research Lab., Gulf Breeze, FL.
||EPA-68-03-3124 ;EPA-68-03-6265; EPA/600/J-89/160;
Rates(Per time) ;
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Fenthion (Baytex), an organophosphate insecticide, is frequently applied to salt-marsh environments to control mosquitoes. Shake-flask tests were used to study rates of abiotic and biotic degradation of fenthion and the environmental parameters that affect these rates. Water or water-sediment (500 mg dry weight/L) slurries from salt marshes located along the Northwest Florida Gulf Coast were used. Flasks contained 200 micrograms fenthion/L, and degradation rates were determined by following decrease of fenthion over time. Hydrolysis and biodegradation in water were relatively insignificant fate processes; fenthion disappeared from flasks containing water, formalin-sterilized water, or formalin-sterilized sediment very slowly (half-life > or = 2 weeks). The presence of nonsterile sediment resulted in a rapid exponential disappearance of fenthion (half-life > or = 3.8 days). Biodegradation was assumed since sterile sediment systems showed a much slower decrease of fenthion, and the production of polar compounds (hexane-unextractable) from radiolabeled fenthion was greater in the presence of sediment than sterilized sediment.