Quality of Danish groundwater reviewed

Geological Survey programme highlights need for continued monitoring of MTBE, Roundup

Levels of nitrates, the petrol additive MTBE and herbicide Roundup (glyphosate) in Danish groundwater should continue to be monitored, according to a survey published by the country's Geological Survey. The survey reports 1999 monitoring results as well as data collected annually since 1993.

Denmark depends more heavily on groundwater for drinking water supplies than any other EU member state. Since 1993, almost 11% of monitored wells have shown levels of pesticides and their metabolites above the maximum admissible concentration (MAC) for drinking water.

This latest report concludes that 8.5% of water supply wells showed nitrate concentrations above the guide level for drinking water and 2% were above the MAC of 25 milligrams per litre. The report's editor told ENDS Daily that not enough monitoring of nitrates took place in the 1990s to provide an overall picture of nitrate concentrations. Reduced concentrations are expected over the next ten years as the impact as a result of a 1987 nitrates action plan.

MTBE has only recently been added to the monitoring programme. Initial results showing contamination of some drinking water wells have already led to a voluntary phase-out of the chemical by the Danish oil industry (ENDS Daily 17 August).

Thus far, glyphosate and its metabolite AMPA have been detected at only very low levels in most cases. However, a Geological Survey official said that, from next year, monitoring of wells less than 20m deep and private wells used for water supply would begin. "If glyphosate is found it might give rise to a renewed discussion" on authorisation of the herbicide, he said.

Follow Up:
Danish Geological Survey, tel: +45 38 14 20 00, English-language summary, and the full report.

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