Excessive inputs of nutrients – nitrogen and phosphorus – cause eutrophication which is the main threat to the Baltic Sea. These nutrients originate from anthropogenic sources like municipal waste water treatment plants, agriculture and industries. High levels of phosphorus and nitrogen cause serious problems in the Baltic Sea: algal and plant growth, increased turbidity, oxygen depletion and changes in biodiversity. Source: HELCOM
These charts show that the levels of Nitrogen and Phosphorus are decreasing in each Baltic Sea subbasin.