An Assessment of Nitrogen Leaching from Watersheds included in ICP on Waters (ICP Waters report)

Abstract

The importance of nitrate in acidification has been evaluated for 163 sites uncluded in ICP on Waters in 13 countries in Europe and North America. At 63 % of these sites yearly average nitrate concentrations amounted to more than 10 % of the acid non-marine acid anions. This shows that nitrate leakage contributes significantly to acidification at a majority of the ICP sites. High leakage of nitrogen occur only at sites with high nitrogen concentrations in precipitation and high total deposition of nitrogen (wet+dry). 144 ICP sites were classified according to Stoddard's system for stages of nitrogen saturation. Approximately one half of the sites had a high degree of nitorgen saturation (Stage 2 or 3). There was a clear coherence between stage classification and total N deposition