The contribution of neighbouring countries to pesticide levels in Dutch surface waters.
Compared with other European countries, Dutch consumption of pesticides is high, particularly in agriculture, with many of the compounds found in surface waters in high concentrations and various standards being exceeded. Surface water quality is routinely monitored and the data obtained are published in the Dutch Pesticides Atlas. One important mechanism for reducing pesticide levels in surface waters is authorisation policy, which proceeds on the assumption that the pollution concerned has taken place in the Netherlands. The country straddles the delta of several major European rivers, however, and as river basins do not respect national borders some of the water quality problems will derive from neighbouring countries. Against this background the general question addressed in this article is the following: To what extent do countries neighbouring on the Netherlands contribute to pesticide pollution of Dutch surface waters? To answer this question, data from the Pesticides Atlas for the period 2005-2009 were used. Border zones with Belgium and Germany were defined and the data for these zones compared with Dutch data. In the analyses, due allowance was also made for authorised and non-authorised compounds and for differences between flowing and stagnant waters. Monitoring efforts in the border zones and in the Netherlands were also characterised, showing that efforts in the former are similar to those in the rest of the country. In the border zone with Belgium the relative number of non-authorised pesticides exceeding the standards is clearly higher than in the rest of the Netherlands. These exceedances are observed mainly in flowing waters. In contrast, there is no difference in the relative number of standard-exceeding measurements between the border zones and the rest of the Netherlands. In the boundary zones the array of standard-exceeding compounds clearly deviates from that in the rest of the Netherlands, with compounds authorised in the neighbouring countries but not in the Netherlands, such as flufenacet, featuring prominently. The share of the neighbouring countries in the total number of exceedances in the Netherlands is roughly proportional to the relative area of the border zones. Although there is a certain influx of pesticides from across national borders, the magnitude of the problem appears to be limited.
Department of Conservation Biology, Institute of Environmental Sciences, Leiden University (CML), P.O. Box 9518, NL-2300 RA Leiden, The Netherlands. zelfde@cml.leidenuniv.nl
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D001530:Belgium; D004784:Environmental Monitoring / Q000379:methods*; D005858:Germany; D009426:Netherlands; D010575:Pesticides / Q000737:chemistry*; D045483:Rivers / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D014877:Water Pollution, Chemical / Q000517:prevention & control*
D010575:Pesticides; D014874:Water Pollutants, Chemical