Kvävet och havsmiljön runt Sverige / Nitrogen and the marine environment around Sweden
The arguments for and against nitrogen removal have been penetrated. Special attention has been taken to the report by the panel of experts Naturvårdsverket (the Swedish Environmental Protection Board) has ordered. None of the arguments for nitrogen removal have been found to be valid for either Baltic Sea or the west coast.
Bothnian Sea can be compared to the Baltic Sea (Baltic Proper) with respect to proportion of nitrogen fixation except that the nutrient level is lower. Phosphorus is the limiting substance from the Bothnian Bay to Skagerrak. A simple model has been applied, which can predict the situations. With the model effects of altered nitrogen
input can be predicted. For the Baltic proper about half of nitrogen in the productive surface water derives from nitrogen fixing bluegreen algae. For the Bothnian Sea the proportion is about a third. For Kattegat the need for nitrogen fixation is varying from zero and upwards. Reduced nitrogen input will likely reduce levels of dissolved oxygen in bottom waters. The situation can improve if the loading ratio P/N is reduced. This is valid for Kattegat, Baltic Proper and Bothnian Sea. For Skagerrak nitrogen removal will make no difference.