Excessive amounts of nitrogen and phosphorus
Two main nutrients are to blame for eutrophication in the Baltic Sea: nitrogen (N) and phosphorus (P).
The Baltic Sea contains 5 times as much nitrogen and 8 times as much phosphorus as it did 100 years ago.
About 80% of the inputs come from land-based activities, including sewage, industrial and municipal waste and agricultural run-off. The rest is mainly from nitrous gasses, emitted when burning fossil fuels, from traffic, industry, power generation and heating.