How oxygen deficiency in the Baltic Sea proper has spread and worsened: The role of ammonium and hydrogen sulphide.

ABSTRACT: Even large inflows of oxygen-rich seawater to the Baltic Proper have in recent decades given only short-lived relief from oxygen deficiency below the halocline. We analyse long-term changes in oxygen deficiency, and calculate the "total oxygen debt" [Formula: see text]OD, the oxygen required to oxidize the hydrogen sulphide (H₂S) and ammonium (NH₄) that builds up during stagnation periods. Since the early 1990s, oxygen below 65m has gradually decreased during successive stagnation periods, and the [Formula: see text]OD has increased, with NH₄ more important than previously recognised. After the major inflow in 2014, the Baltic Proper [Formula: see text]OD has reached its highest level so far. The gradual shift of the [Formula: see text]OD to shallower sub-h

SUBMITTER: Rolff C 

PROVIDER: S-EPMC9481832 | biostudies-literature | 2022 Nov

REPOSITORIES: biostudies-literature