OCEANIC AMMONIA EMISSIONS IN EUROPE AND THEIR TRANSBOUNDARY FLUXES

Annual biogenic emissions of ammonia from European seas and their tran sboundary flows are estimated. Atmospheric fluxes are calculated from monitored seawater ammonium (NH4+) levels, via a compensation point ap proach in the acid deposition model of the MSC-W of EMEP. Mean monthly emissions exhibit a September peak of around 100 mu g NHx-N m(-2) d(- 1) across both the North and Baltic Seas. Total emissions approximate those of smaller countries, although seas export larger proportions th an land areas. Contributions to NHx-N deposition approach 5% in coasta l regions of Scotland. Although fluxes are small, seas may represent t he 3rd and 4th largest source of imported NHx-N to the Republic of Ire land and the U.K., respectively. Uncertainty associated with the seawa ter data is between -40% and +80% of the best estimate. (C) 1998 Elsev ier Science Ltd. All rights reserved.