Methodology for Overland and Instream Migration and Risk Assessment of Pesticides

摘要

To provide planners and decision makers in government and industry with a sound basis for decision making, the Chemical Migration and Risk Assessment (CMRA) Methodology was developed to predict the occurrence and duration of pesticide concentrations in surface waters receiving runoff from agricultural lands and to assess potential acute and chronic damages to aquatic biota. The CMRA Methodology consists of overland pesticide transport modeling, instream pesticide transport modeling, statistical analysis of instream pesticide concentrations, and risk assessment. The CMRA methodology uses the state-of-the-art overland and instream models ARM and SERATRA to continuously simulate nonpoint source pollution processes. It is useful for evaluating both short and long-term migration and fate of both dissolved and particulate pesticides. The risk assessment procedure, coupled with the statistical analysis of predicted instream pesticide concentrations by the computer program FRANCO, and pesticide toxicity data provides a good scientific basis for pesticide risk assessment. Because of a lack of extensive knowledge on pesticide toxicity, however, the risk assessment procedure includes only the direct effects of dissolved pesticide concentrations on aquatic biota. The risk assessment does not include ingestion effects or any indirect effects such as bioconcentration and biomagnification. The methodology is general enough to handle heavy metals, radionuclides, and other toxic contaminants as well.