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Abstract

Only recently has the importance of atmospheric input into marginal seas like the North Sea been emphasized for several heavy metals and nitrogen components. The few data for the open sea, however, have left large uncertainties in quantitative estimates (Cambray et al. 1975). Modelling indicated that there should be a steep decrease in deposition depending on meteorological conditions, and that coastal stations overpredict the input substantially (van Aalst et al. 1983; van Jaarsveld et al. 1986; Krell and Roeckner 1988, see also Chapt. 3.1). The presented studies therefore focussed on measurements at sea in comparison with coastal sites. On the island of Helgoland and at the research platform Nordsee as well as on cruises in the North Sea, concentrations of components of interest and their deposition were monitored over a period of years and compared with a reference station at the Westerhever lighthouse. Wind-directed sampling at the island of Helgoland was carried out to characterize the air masses reaching the German Bight from different source regions. The interpretation of these measurements and intensive field measurements together with calculated backward trajectories and long-term wind direction frequencies permitted quantification of the contributions from different source regions to the atmospheric input into the German Bight