The Baltic Sea suffers from serious oxygen deficiency. Even large inflows of oxygen-rich seawater have in recent decades only provided short-term relief from oxygen deficiency in the deep water. In the latest issue of Ambio, a new method for quantifying the total oxygen debt from Öresund to Åland is presented. By using existing data dating back to the 1960s, the researchers show that we have gone from a supply of about 10 million tons of oxygen in the deep water to a net oxygen supply close to zero, with an oxygen debt of up to 4 million tons caused by accumulated hydrogen sulfide and ammonium. In the last 20 years, the oxygen debt has also spread to near-halocline waters west of Gotland.
The Baltic Sea oxygen debt worse than ever - Read the full article