Balticsea 2020

Simulations of some engineering methods proposed to improve oxygen conditions in the Baltic proper

In recent years engineers have put forward several potential technical solutions to cure the dead bottoms of the deep Baltic Sea. In this project, “Simulation of the effects of some engineering measures aimed at reducing effects from eutrophication of the Baltic Sea”, some of these engineering measures were tested through modeling of the effects that these measures would have on the Baltic Sea.

Result
The results of the project showed that hypoxia causes a general increase in primary production and in particular an increase in the summers blooms of cyanobacteria in the Baltic Sea. The theoretical amount of oxygen needed to counter the lack of oxygen is in the range of 2-6 * 106 tons / year. This is equivalent to 20,000 to 60,000 rail cars of liquid oxygen per year. All forms of modeling that affect the exchange through the Danish Straits involves changes in the salinity of the Baltic Sea. They show that measures that increase the salinity worsens oxygen situation and the measures that reduce salinity improves oxygen levels. The improvement occurs only after a long transitional period where the lack of oxygen remaining in the deeper parts. The conclusion is that it is not possible to quickly improve the oxygen situation by technical means to affect the water exchange through the Danish Straits. The models showed that the halocline ventilation provides an improved oxygen situation with no change in surface water salinity. A reduction in deep water salinity was observed, but it was within the natural variation and should not affect biodiversity. Halocline ventilation was the only technical proposals for action that are not rejected in this study.