Evaluation of Humic-Pesticide Interactions on the Fate and Effects ofAgricultural Chemicals

摘要

An understanding of the behavior of pesticides in freshwater ecosystems isessential to accurately predict the toxicity of these agricultural chemicals in the environment, as well as to the development of reliable water quality standards. Dissolved humic materials are important constituents of the dissolved organic carbon pools in most lakes and streams. These ubiquitous components of the chemical matrix of aquatic ecosystems can affect the availability and toxicity of chemicals in the environment. In view of these considerations, a two-year investigation was undertaken to evaluate the toxicological consequences of humic-pesticide interactions on the fate and effects of agricultural chemicals. A combination of antagonistic and synergistic effects was observed with the organophosphate and carbamate insecticides. On the other hand, a clear indication of reduced toxicity was observed with the pyrethroid insecticides and triazine herbicides. As with the organophosphate and carbamate insecticides, a combination of antagonistic and synergistic effects was observed with glyphosate. Humic acid had no significant influence on the toxicity of the herbicides, monosodium methanearsonate pentachlorophenol and trifluralin. In addition, a series of studies were conducted to examine the influence of different sources of dissolved humic material on the acute toxicity of the pyrethroid insecticides. These data indicate that humic interactions influence the toxicity of chemicals, however, the magnitude of influence is dependent on the source of humic material and pesticide of concern.