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(80-86) GIS post-registration monitoring of pesticide concentrations in surface water. van Hooft, Pim*,1, de Snoo, Geert1, Udo de Haes, Helias1, 1 Centre of Environmental Science, Einsteinweg 2, Leiden, Zuid-Holland, Netherlands ABSTRACT- A pilot study has been conducted on the possibilities of presenting surface water concentrations of pesticides in the Netherlands graphically in the form of an atlas. Such an atlas could be used for different purposes. It gives information about where a pesticide is being measured, observed and eventually poses a problem. Also, one can judge the quality of the current monitoring system. Most importantly, surface water concentrations may be related to pesticide - and land use, which can subsequently be used as a feedback to the admission of pesticides in the Netherlands. For the pilot study measurements from the Commission of Integral Water Management (CIW) of 1997 and 1998 were used. As an example, maps were made for six pesticides: atrazin, carbendazim, iprodion, metribuzin, propoxur and vinchlozolin. In presenting the data, the Netherlands were divided in 5x5 km2 squares. Pesticide concentrations were compared to three standards: the standard for drinking-water, the maximum allowable risk level (MTR) and the admission standard set by the Board on the Admission of Pesticides (CTB). From the results it is concluded that one gets a good spatial view per pesticide and that with most pesticides a connection is possible with pesticide- and land use. Furthermore, gaps are made apparent in the monitoring system. The study resulted in several relevant new insights. Exceedings of standards were observed in areas and times of the year where one, on basis of data on land- and pesticide use, does not expect them. As an example of possible consequences of these insights, admission of pesticides that still are exceeding standards in the winter months may have to be reevaluated. Key words: GIS, pesticide, surface water, atlas |
