Cruise report from M/V Meri week 4-5, 2018

Type: Report
Author: Örjan Bäck, Johan Kronsell


In large areas of the Baltic Proper, the oxygen concentration in the deep water was close to zero. Anoxic conditions, when hydrogen sulfide can form, were found in the Western Gotland Basin from 80 meters depth and from 90-125 meters in the northern parts. In the Eastern Gotland Basin low levels of hydrogen sulfide were found, but only close to the bottom. Acute hypoxia (oxygen <2ml/l) was found in the Bornholm Basin, and in the Bight of Hanö at about 40-50 meters depth, in southeastern Baltic Proper at 60 meters, and in Eastern and Western Gotland Basin at 70 meters depth. In the Arkona Basin the oxygen concentration closest to the bottom was about 3.5 ml/l.

The surface concentration of dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP) was in general on normal levels for all of the areas monitored. The silicate concentration in all of the Baltic Proper was still above normal.