Deposition of acidifying components and base cations in Germany in the period 1987-1995

This report describes the results of the project: 'Deposition of acidifying components and base cations in Germany in the period 1987-1995'. The project was carried out by RIVM on behalf and for account of the National Environmental Agency 'Umweltbundesamt' (UBA) in Germany in co-operation with TNO and Alterra in the Netherlands. For Germany, the research carried out has yielded, as main product, estimates of dry deposition with a high spatial resolution. These, in combination with wet deposition data, will be used for calculating critical load exceedances. The basic model used in this study is EDACS, which calculates dry deposition fluxes on the basis of meteorological data and atmospheric concentrations of relevant species. Atmospheric concentrations were taken from results of the EMEP model (SO_2 and NO_x), the EUTREND model (NH_x) and wet deposition measurements (base cations). SO_x dry deposition fluxes were largest in eastern Germany; NO_y fluxes in central-west Germany and NH_x fluxes in north-west Germany. The highest dry deposition of potential acid (up to 20,000 eq ha"-"1y"-"1 as average for the period 1987-1989) was calculated for eastern Germany and the highest dry deposition load of nitrogen (up to 3500 eq ha"-"1 y"-"1 as average for the period 1987-89) for North Rhine-Westphalia. Dry deposition of SO_x, NO_y, NH_x and potential acid in the period 1993-95 decreased by 49%, 13%, 21% and 42%, respectively, compared to the 1987-89 period. Dry deposition of non-sea-salt Ca"2"+, K"+, Mg"2"+ and base cations decreased in the 1993-95 period by 42%, 24%, 65% and 43%, respectively. On average, the modelled dry deposition of NH_x, Mg"2"+, Ca"2"+ and K"+ can be concluded as not significantly different from dry deposition derived from throughfall measurements, although a considerable scatter can be observed. The comparison reveals an overestimation of the dry deposition of SO_x, NO_y and Na by factors of 1.67, 1.58 and 1.75, respectively. (orig.)Available from TIB Hannover: RN 8908(2000,81) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLENational Inst. of Public Health and Environmental Hygiene (RIVM), Bilthoven (Netherlands)DEGerman