ENVIRONMENTAL FATE OF PHORATE AND ITS METABOLITES IN NORTHERN PRAIRIEWETLANDS

The environmental fate of the organophosphate insecticide phorate and its metabolites, phorate sulfone and phorate sulfoxide Was examined in mesocosms placed in South Dakota wetlands. Three treatment concentrat ions of phorate (1.2, 2.4, and 4.8 kg/ha) were applied to wetland meso cosms. Phorate, phorate sulfone, and phorate sulfoxide were present in water and sediment during the entire study (28 days) in all treatment s. Maximum phorate concentrations in water were measured one day after treatment and decreased significantly during a 28-day period. The met abolites of phorate increased significantly in the water during the st udy. Phorate was present in higher concentrations in sediments than ei ther phorate sulfone or phorate sulfoxide throughout the study.