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We use data collected on 52 cruises from 1960 to 1995 to analyze the decadal variability in basic chemical properties (oxygen, sulfide, nitrate, phosphate and silicate) throughout the water column of the Black Sea. This analysis reveals some new features in the recent evolution of the chemical structure of the Black Sea: an increase in the inventory of sulfide and nutrients in the anoxic zone, a decrease in the inventory of oxygen in the upper layer, and variations in the thickness of the sub-oxic zone. These changes suggest that an increase in the flux of sinking particulate organic matter (POM) has perturbed the biogeochemistry of the Black Sea. The flux balance that controlled the distribution of nutrients before the early 1970s has been modified due to intensive eutrophication. That has led to an increase in the inventory of nutrients in the anoxic zone due to an increased flux of POM. This increased flux of POM …