Evaluation of Humic-Pesticide Interactions on the Fate and Effects ofAgricultural Chemicals; Bioremediation of Groundwater and Subsoils; Department of Environmental Quality: Information Management Support

摘要

The ability of water resource managers to accurately predict the toxicity ofagricultural chemicals in aquatic ecosystems is essential for the development of reliable water quality standards. At present, accurate predictions are difficult due to the paucity of data concerning the interacton of agrichemicals with organic constituents of the freshwater chemical matrix. Dissolved humic materials are ubiquitous components of freshwater ecosystems and can affect the availability and toxicity of chemicals in the evironment. In the present investigation, the influence of humic acid (HA) on the toxicity of a suite of pesticides used extensively in Mississippi and the South Atlantic-Gulf region was examined using a bacterial bioluminescence ihibition assay. The assay is based on the inhibition of bioluminescence of Photobacterium phosphoreum in the presence of test chemicals. EC50 values for the pesticides were determined in the presence of 0, 0.5, 5.0, 50, and 100 mg/liter HA.