Long-period variability of oxygen dissolved in Black Sea waters

Using an archival database from the Institute of Natural and Technical Systems, the low-frequency variability of oxygen dissolved in the deep-water and northwestern parts of the Black Sea for the period of 1955–2004 is analyzed. The upper mixed layer (UML) is characterized by quasi-periodic variability in the dissolved oxygen concentration in the interdecadal scale. Deeper, a long-term decrease in the oxygen concentration is recorded.