Source receptor relations for the calculation of atmospheric deposition to the North Sea: Nitrogen and Cadmium

Abstract

In this report a simplified atmospheric transport model for estimating the deposition of nitrogen (both NOx and NHx) and cadmium to the North Sea is presented. In this so-called meta-model a linear relationship between the emissions from a source area and the resulting deposition at receptor points is assumed. Given such source-receptor relations the deposition load to the North Sea may easily be calculated for any emission scenario. The source-receptor relations are based on extensive calculations by means of the atmospheric transport model TREND. In TREND atmospheric processes such as transport, dispersion, chemical conversion and wet and dry deposition are accounted for. The definition of source areas is in agreement with the classification applied earlier in the Dutch Acidification System model (DAS model). In the Netherlands 20 source areas, in Europe 19 areas have been defined. Additionally, the North Sea itself is defined as source area 40. The receptor points selected in this study are irregularly distributed over the North Sea and surrounding countries. In areas where a strong spatial gradient in deposition flux is expected (coastal regions, southerm part of the North Sea) receptor point density is set higher. Using these determined source-receptor relations avoids computer-time consuming TREND calculations without significant loss in accuracy. This emission-deposition model will be coupled with the water quality models within the framework of the MANS-project.<br>