Nitrate in groundwater

Generic metadata

Classification

Identification

Mean nitrate concentrations in groundwaters in Europe are above background levels (3) (EEA, 2000)) but do not exceed 50 mg/l as NO₃. Due to a very low level of mean nitrate concentrations (NO3) in the Nordic countries the European mean nitrate concentration shows a biased view for nitrate. Hence the presentation is separated into Western Europe, Nordic Countries and Accession Countries. In Western Europe the mean nitrate concentrations in groundwaters are above the Drinking Water Guide level (> 25 mg/l as NO₃). Further details are shown in Sub-indicator 1. Additional information has to be taken into account (see Sub-indicators) for the interpretation of the figures as they may have a strong influence on the quality data provided (e.g. type of GW-bodies and type of monitoring sites).

According to the latest European Commission report [1] there is a high and stagnant level of nitrate concentrations in groundwater. The general trend in nitrate concentrations in groundwater when comparing the first (1992-1994) and second (1996-1998) monitoring exercise is summarised as "stable to increasing". Countries showing an overall increase in nitrate concentrations in groundwater are France and Sweden [1].

It is very difficult to prove a direct context between the application of nitrogen fertiliser in agriculture and the nitrate content in groundwaters as there is often a significant time lag between changes in agricultural practices and changes in nitrate concentrations in groundwater of up to 40 years, depending on the hydrogeological conditions [4].

The map of nitrate problem areas in EEA (2000) and statements in several State of the Environment (SoE) reports indicate that the provided information might not fully reflect problems with nitrate in groundwater in Europe as several nitrate problem areas mentioned in the SoE reports are not reported to EUROWATERNET.

Furthermore, low nitrate concentration levels can occur due to reducing conditions. Therefore the Sub-indicator 6 on ammonium has been introduced to provide complementary information.