USE OF SOIL MICROCOSMS IN ASSESSING THE EFFECT OF PESTICIDES ON SOIL ECOSYSTEMS

摘要

In recent years, considerable interest has been shown in model ecosystem techniques to predict the environmental impact of pollutants. The microcosms usually consist of soil units containing multiple biotic species that range in size from 0.05 dm~3 of soil to units of up to 1 m in diameter and that have more than 1 m~3 of soil. They include single species assays, mixed soil containing a range of organisms and intact soil cores from the field ecosystems they represent. Model ecosystem tests assess in an integrated form the impact of toxicants on soil organisms and soil processes at different levels of biological organization. At the same time, degradation of a pesticide and its leaching, volatilization and movement into plants and invertebrates can be followed. Such systems lend themselves readily to the use of radiolabelled pesticides, as well as stable isotopes such as ~(13)C and ~(15)N, to follow pesticide and nutrient transformations in soil. The Ohio State University (OSU) has developed an integrated, small scale soil microcosm to assess the effect of pollutants on soil ecosystems. This integrates the effect of chemicals on typical soil organisms (soil microbes, microarthropods, nematodes and earthworms) with data on the consequences of chemical contamination on soil ecosystem processes (nutrient cycling, enzyme activity and organic matter decomposition). It also