Ecological effects of pesticide use in the Netherlands:Modeled and observed effects in the field ditch

摘要

This study dealing with risks to the aquatic ecosystem imposed by theapplication of pesticides in the Netherlands made use of a novel methodto calculate aquatic exposure to a large variety of pesticides (261 intotal), which is worked out in detail here. Since the entire calculationis founded on GIS-based maps of agricultural land use (51 crops in openculture), it is possible to generate country-wide maps of the results. Through the application of Sensitivity Distributions for aquatic species(SSD), in combination with rules for mixture toxicity calculation, themodeled exposure is transformed to a risk estimate for the speciesassemblage in the aquatic ecosystem. The risk is expressed as theproportion of species likely to be suffering any effect from theexposure. In the summary of the risk maps, the majority of predictedeffects is observed to be caused by the pesticide application practice ingrowing potato crops: 95% of the predicted risk is caused by only 7 ofthe 261 pesticide ingredients. The maximum local risk of pesticide useis estimated to affect about 50% of species. For the purpose ofvalidation, local toxic risk estimates were compared to observed speciescomposition in field ditches using simple statistical methods (regressionanalysis). However, the number of field observations was not sufficientenough to generate quantitative results. The unexplained variability inthe biotic field data collected by a range of non-aligned monitoringnetworks does not allow highly significant conclusions. Nevertheless,there is a weak indication that the predicted risks are associated tobiodiversity changes in field-exposed communities.