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(77-18) The Development and Application of an Environmental Quality Indicator for Pesticides. Peijnenburg, Willie*,1, Hollander, Henri1, Luttik, Robert2, Meent, Dik1, Zwart, Dick1, 1 RIVM, Laboratory for Ecotoxicology, Bilthoven, The Netherlands2 RIVM, Center for Substances and Risks, BilthovenThe Netherlands, The Netherlands ABSTRACT- An environmental quality indicator for the occurrence of chemicals in the Dutch environment is presented. The indicator allows for assessing both the extent to which environmental quality objectives are exceeded, and the underlying time trends. The indicator is of the so-called distance-to-target type and is based upon measured concentrations of pesticides. The quality indicator has been applied to monitoring data of pesticides in Dutch surface waters during the years 1992 - 1998, and to monitoring data regarding pesticides in rain in the years 1992 and 1998. It was found that target values for pesticides in surface waters are exceeded considerably. There is, however, a trend of decreasing pesticide levels in surface waters at the national aggregation level during the years 1992-1994. Levels tend to stabilize during the years 1994 - 1998. Exceedance of target values is more pronounced in Dutch regional waters than in the major Dutch rivers. Pesticides that have been banned in the Netherlands exceeded the target values for surface water only slightly. Higher levels of pesticides are generally found in rainwater than in surface water. This is also the case for pesticides that were banned. The monitoring data that were used, relate to about 80% of the annual tonnage of pesticides used in the Netherlands. Earlier investigations showed that 80-90% of the total (potential) toxic pressure is caused by only 10 pesticides, a number of which was not represented in the monitoring data base. It is estimated that about 40-50% of the toxic pressure in Dutch surface waters is not included in the quality indicator presented here. Due to the lack of monitoring data, the indicator presented should be seen as a minimum estimate of the 'true' value. For the same reason it was only possible to a limited extent to get a true nation-wide overview of the indicator. Key words: Pesticides, Indicator, Monitoring, Water quality |
