Organic carbon burial rates in the Baltic Sea sediments

•22 sediments cores were collected from the Baltic Sea deposition areas.•Carbon deposition to and carbon return flux from the sediments were established.•Basing on the above burial rates of carbon in the Baltic sediments were evaluated.•The burial rates allowed better estimates of carbon budget of the sea.

Recent studies indicate the important role of the marine environment in the circulation of CO2. This is due to the occurrence of the so called “biological pump” mechanism. A special role in this process is played by the shelf seas. The paper presents estimates of organic carbon burial rates in the Baltic Sea sediments. Quantification of the burial rate required the determination of organic carbon accumulation rate to the Baltic sediments and the carbon return flux from sediments to the water column. Results of both sediment and mass accumulation rates as well as profiles of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) were used. Sediment accumulation rates were based on 210Pb method validated by 137Cs measurements and ranged from 66 g m−2 yr−1 to 744 g m−2 yr−1 as regards mass accumulation rates and from 0.07 cm yr−1 to 0.25 cm yr−1 as regards linear accumulation rates. Carbon deposition to the Baltic sediments amounts to 1.955 ± 0.585 Tg m−2 yr−1, while 0.759 ± 0.020 g m−2 yr−1 of carbon returns from sediments to the water column. Thus the organic carbon burial rate in the Baltic Sea sediments is equal to 1.197 ± 0.584 Tg C m−2 yr−1.

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