Acidifying and Eutrophying Pollutants

Acidifying and eutrophying pollutants originate primarily from anthropogenic emissions of sulphur dioxide (SO2), nitrogen oxides (NOx) and ammonia (NH3 ). Most of SO2 and NOx is emitted to the atmosphere under the combustion of fossil fuel in electricity generating power stations, industrial plants, residential heating, commercial and service sectors. Road transport, shipping and aircraft are significant sources of NOx emissions. NH3 emissions are related to agricultural activities such as storage of manure, soil fertilising, animal husbandry, etc.

When emitted to the atmosphere, acidifying and eutrophying pollutants may remain in air for several days and therefore, be dispersed and carried over long distances by winds. They can be transported across national boundaries and cause damaging effects far from the source of emission. Acidifying pollutants are removed from the atmosphere by wet ("acid rain") or dry (direct uptake by vegetation and surfaces) deposition.

Effects of acid deposition are widespread and appear in a number of ways, including e.g. acidification of freshwater systems resulting in the loss of fisheries, impoverishment of soils, damage to forests and vegetation, corrosion of buildings, cultural monuments and materials. The man-made gaseous sulphur and nitrogen emissions are precursors to the formation of small particles (PM2.5) which impact human health. Deposition of nitrogen-containing compounds also contributes to the eutrophication ("excess nutrient enrichment") of terrestrial and marine ecosystems. Their eutrophying effect is associated with increased leaching of nitrogen to ground water, streams and lakes and changes in the forest ecosystems leading to vegetation changes favouring nitrogen-tolerant species.
 

Emissions

The UNECE/EMEP emission database WebDab has been constructed in purpose to facilitate the access to the emission data reported to the Convention on Long-Range Transboundary Air Pollution (CLRTAP) on Main Pollutants among other compounds.

Measurements

Measurement data is available for all EMEP stations.

Model descriptions

Until 1998, 2-D Lagrangian Acid Deposition model was routinely used at EMEP/MSC-W. In 1999 a 3-D Eulerian Acid Deposition Model was applied to calculate air concentration and deposition fields for major acidifying and eutrophying pollutants as well as their long-range transport and fluxes across national boundaries. But this model has been revised and is documented in EMEP Status Report 1/03 Part I (available at: common EMEP publications) and from 2003 the operational runs are done with Unified EMEP model.

Model results

Modelled air concentration and deposition data are downloadable as ASCII files covering the whole EMEP grid. Source-receptor relationships by country of Sulphur and Nitrogen are downloadable as ASCII files, but also overview tables of Sulphur and Nitrogen are available.