"Nutrient levels in soil and water must not be such that they adversely affect human health, the conditions for biological diversity or the possibility of varied use of land and water."
Eutrophication – nutrient over-enrichment – affects not only lakes, rivers and seas, but also soils. It is a problem above all in the south of Sweden, but there are indications that mountain areas are also affected. Eutrophication causes gradual changes in vegetation, as species adapted to nutrient-poor conditions are displaced.
In the Baltic in particular, eutrophication is one of the most serious threats to the marine environment. In both sea areas and lakes, symptoms include plant overgrowth and algal blooms. In the worst cases, oxygen depletion occurs on the sea or lake bed, killing plants and animals. If blooms are formed by toxin-producing algae, both human and animal health can be threatened.
Eutrophication is caused by excessive levels of nitrogen and phosphorus in soil or water. These nutrients can enter the environment via atmospheric emissions, for example of nitrogen oxides from road traffic, shipping and power stations. Other sources of eutrophication are run-off from agriculture and discharges from sewage treatment plants and factories.
What are the challenges?
Further reductions need to be achieved in nutrient inputs to lakes, rivers and seas from Sweden and other countries affecting the environment of the Baltic, Kattegat and Skagerrak. Under the Baltic Sea Action Plan, Sweden and other nations around the Baltic have pledged to cut inputs by 2021.
Many of the emissions that are of significance for eutrophication are limited by international agreements. For progress to be made, Sweden, like every other signatory state, must fulfil its part of existing accords. Important agreements include the Gothenburg Protocol to the UN Convention on Long-Range Transboundary Air Pollution and the EU’s Water and Marine Strategy Framework Directives.
Emissions to air from road traffic, industry and international shipping also have to be reduced. Most atmospheric deposition of eutrophying pollutants comes from other countries and from international shipping. Further decisions to curb air emissions are therefore needed at the international level.