The most important sources contributing to eutrophication in
the Celtic Seas ecoregion are agriculture, atmospheric deposition, urban waste water, industry, and aquaculture. The major
sources of nitrogen and phosphorous input in the environment are diffuse losses (agriculture and atmospheric deposition) and
sewage treatment works. Atmospheric deposition of nitrogen is estimated to provide about one-third of all inputs of nitrogen.
A major contribution to atmospheric deposition, and therefore to the overall input of nitrogen to the environment, is emissions
from shipping. In the Celtic Seas ecoregion, eutrophication is restricted to inlets, estuaries, and harbours, in particular in areas
of higher population densities and intensive agricultural activities.
