Temporal changes in the carbonate system of the Sevastopol Bay (Black Sea) waters for the last decade

摘要

The carbonate system is one of the most complicated chemical equilibriumsrnin seawater. It concerns with air-sea carbon dioxide (CO_2) exchangernprocesses, with chemistry of seawater and with accumulation of carbonatesrnin marine sediments. CO_2 has a key role in the changes of the seawaterrncarbonate system especially in estuarine and coastal waters. Budget of thisrnsubstance is closely linked to the organic carbon pool throughrnphotosynthesis and respiration. The level of pCO_2 in coastal waters isrnusually higher than other open ocean values and as compared to thernatmospheric pCO_2 allows considering these regions to be additional sourcesrnof carbon dioxide for the atmosphere. This work is aimed to investigate therncarbonate system of anthropogenically stressed and highly eutrophic coastalrnzones of the Black Sea.rnThe carbonate system of the Sevastopol Bay (Black Sea) has beenrnmonitored from 1998 to 2007 to investigate its seasonal dynamic and tornestimate the carbon dioxide (CO_2) flux at the air-sea boundary. Resultsrndemonstrate that the flux of CO_2 from the atmosphere was typical for thernentire area of the bay and for all seasons, as the partial pressure (pCO_2) inrnthe surface waters was usually below than the atmospheric pCO_2. Thernaverage value of pCO_2 in the surface layer of water is 294 matm. However,rntemporal changes of pCO_2 have a tendency of increasing from 226 matm inrnJuly 1998 to 284 matm in July 2007. The bottom layer has demonstrated