Simulation of the Migration, Fate, and Effects of Diazinon in Two Monticello Stream Channels

摘要

A field investigation was conducted on the aquatic effects of diazinon in experimental stream channels at Monticello, Minnesota during the summer of 1980. The field data was used to simulate the transport of diazinon in the water and sediments and to assess the toxic risks to fathead minnows using the Chemical Migration and Risk Assessment (CMRA) methodology. This method required input of channel and hydrologic characteristics, diazinon characteristics and its release rate into a receiving water body, laboratory concentrations of diazinon exposure causing sublethal effects and mortality, and field observations of actual effects on fathead minnows exposed to diazinon. Diazinon, an organophosphate insecticide, was injected into the channels at two low-level concentrations (3.0 micrograms/liter and 0.3 micrograms/liter in receiving channels after mixing). Hydrodynamic and sediment transport models were calibrated using the higher concentration channel. The models then simulated concentrations in the other channel. The risk assessment used a statistical summary of the modeling results and laboratory toxicity data to determine the probable consequences of continuous exposure of the fish to the two diazinon concentrations. Results of the modeling application were encouraging. The predicted hydrodynamic simulation concentrations were generally equivalent with measured field concentrations.