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(46-08) Linking pesticides in streams to catchment characteristics, usage and physicochemical properties. Iversen, Hans*,1, Sørensen, Peter2, Jensen, Jens Peder1, 1 National environmental research institute, Silkeborg, Denmark2 National environmental research institute, Roskilde, Denmark ABSTRACT- In the Danish national monitoring program of 48 different pesticides have been monitored in 25 streams draining agricultural catchments during the year 2000. Relationships between the overall pesticide loading and catchment characteristics have been tested. It appeared that pesticide loading in streams was significantly correlated with catchment soil type and hydrology. Secondly the observed ranking of the 20 pesticides with farm usage in 2000, based on the occurrence have been reproduced by using descriptors for the usage and physicochemical properties. It have been demonstrated how relatively simple descriptors were able to reproduce the rank of the data with high degree of success. These descriptors were easy to obtain for all substances also concerning pesticides not included in the monitoring campaign. Thus it were possible by using the descriptors to rank both the substances which have been included in the campaign and the remaining substances together. In that way it was possible to predict the possible occurrence of a not investigated substance by using the rank in relation to the substances which were monitored. Thirdly, multivariate techniques have been tested in order to make comparisons between the pesticide data and further with the aim to unravel more complex relationships between pesticide loads in streams and catchment characteristics, usage and physicochemical properties. Key words: Monitoring, Streams, Pesticides, Assessments |
