Pesticides in Groundwater

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The consumption of pesticides by weight is decreasing. A main reason seems to be the application of more efficient pesticide substances which are applied in smaller quantities. But it is the toxicity of an individual pesticide, not necessarily the amount used, which determines its potential for environmental damage. In the Accession countries pesticide consumption decreased dramatically in the past decade, mostly due to a general decline of the national economy. In Estonia the consumption dropped by 78 %, in Latvia by 86 %, in FYR of Macedonia by 75 %. In Czech Republic the consumption in 1999 corresponded to 47 % of the consumption in 1990. However, the consumption of pesticides is currently reversing. (SoE-EE, 2002; SoE-LV, 1996; SoE-MK, 2000; SoE-CZ, 1999). A further major threat to groundwater are pesticides which are inappropriately stored. Albania reports 500 tons of pesticides being damaged due to inappropriate conservation and storage (SoE-AL, 1999). The 2nd Baltic State of Environment Report gives an account of 1500 identified unsafe pesticide storage sites in Estonia, Latvia and Lithuania in 1996. The amount of accumulated old stocks was about 4500 t, consisting of several banned substances and a considerable amount of those pesticides were not yet identified in 1996. In Lithuania the heaviest pesticide pollution was found around pesticide warehouses. Main contributors are HCB, chloro-organic insecticides and triazines (BSoER, 2000). The awareness of pesticides causing problems in groundwater is still increasing. A lot of effort is being made by countries in investigating the situation of pesticide pollution. A lot of additional effort is necessary to provide a comparable overview at the European level. However, all countries but Sweden, reporting on the pesticide situation in their State of Environment reports, mention danger of pesticide pollution of groundwater. In Austria between mid 1997 and mid 1999 about 15 % of sampling sites exceed 0.1 µg/l for desethylatrazine and 10 % for atrazine. Within these 2 years 490 000 pesticide analyses (on 59 pesticides) had been performed. Trend analyses for atrazine of 247 sampling sites showed significant downward trends at 72 % of the sites. Atrazine was banned in 1995 and the ban seems to be effective (UBA, 2001). In France over half of all monitoring sites (52 %) are considered to be unaffected. Excessive contamination is suspected at 35 % of sites and definitely present at 13 % of sites. However the available data covers only 75 % of France (RNDE, 2002). In Denmark, in 2001, pesticides were found to be present in 27 % of the well screens and concentrations of pesticides in 8.5 % of the screens exceeded the limit value for drinking water (GEUS, 2002). In the UK in 2000 about 9 % of the freshwater sites failed to meet the Environmental Quality Standards at least once (ENVIRONMENT AGENCY, 2002). Even Sweden, which confirmed that pesticides do not cause problems in groundwater, reports on sometimes low but not insignificant concentrations of pesticides in groundwater (Swedish EPA, 2002).