Processes affecting deposition of oxidised nitrogen and associated speciesin the coastal areas of Norway

Measurement data on air, precipitation and canopy throughfall chemistry fro m a network of sites have been combined to study scavenging and deposition processes, with particular emphasis on the oxidised nitrogen species. High deposition rates of oxidised nitrogen occur in coastal areas of SW Norway. These are partly caused by high precipitation rates, partly also because a large fraction of the oxidised nitrogen is present as nitrate in large part icles, which are rapidly removed by both wet and dry deposition processes. High wind speeds near the coast result in high concentrations of sea-salt p articles in the air and high deposition rates of both nitrate and sea-salt particles, particularly in coniferous forest stands. HNO3 contributes on av erage only about 10-20% to the sum of aerosol nitrate and HNO3 (sNO(3)). St ill, the combined dry deposition velocity of sNO(3) to these forest stands may be between 4 and 6 cm s(-1) on average. (C) 1999 Elsevier Science Ltd. All rights reserved.