The impact of pesticides in soil

摘要

Binding of pesticides in soil reduces their mass transport and degradability. On the other hand sorption to dissolved organic matter (DOM) and to soil particles can lead to co-transport of pesticides within the soil profile. Important for the assessment of the ecological relevance of bound pesticide residues in soil are both the structure and the binding mechanism which can be elucidated by NMR-spectroscopy. Although various mechanisms exist for binding of pesticides to soil, rather high pesticide concentrations are sometimes observed in ground water. This phenomenon is often due to co-transport connected with rapid water flow through macropores in soil. Macropores are produced by earth worms, plant roots and freeze-thaw or dry-wet cycles. Pesticide transport is enhanced if the macropores end in soil regions with high water permeability. Less macropore leaching is observed in regions with soil undergrounds of low water permeability such as loess soils.