Evaluation of the impact of changes in atmospheric emissions of nitrogen on primary production in the Kattegat
The final component of MEAD has involved the development of a methodology to estimate how changes in nitrogen emissions to the atmosphere affect nitrogen deposition to the Kattegat under different emission control strategies and what the impact of this on phytoplankton production in surface waters is likely to be. Our results show that atmospheric nitrogen inputs are probably not large enough to trigger summer blooms in the Kattegat and that blooms most likely result from inputs of nutrients from deep water during wind driven mixing. Results do however show that the atmosphere is an important source of nitrogen to the region and will contribute to eutrophication. They also suggest that reducing nitrogen inputs from the atmosphere will result in a decrease in primary productivity. To achieve this reduction in atmospheric nitrogen inputs we need regional scale regulation for ammonia which is deposited close to its source and European wide legislation for NOx which undergoes significant long range transport prior to deposition. Although based in the Kattegat, we believe the conceptual understanding we have achieved within the MEAD project is transferable to other coastal regions.