High anthropogenic carbon content in the eastern Mediterranean

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Abstract

[1] This work presents data of dichlorodifluoromethane (CFC-12), dissolved inorganic carbon and total alkalinity from a cruise to the Mediterranean Sea during October–November 2001, with the main focus on the CFC-12 data and on the eastern basin. Using the transit time distribution method, the anthropogenic carbon concentrations in the basin were estimated. Results were cross-checked with a back-calculation technique. The entire water column of the Mediterranean Sea contains anthropogenic CO2, with minimum concentrations of 20.5 μmol kg−1 (error range: 16.9–27.1 μmol kg−1) in the most eastern part of the basin at intermediate depths, where the waters' mean age is >130 yr. Column inventories of up to 154 mol m−2 (132–179 mol m−2) are found and a total inventory of 1.7 Pg (1.3–2.1 Pg) of anthropogenic carbon in the Mediterranean Sea was estimated. There is a net flux of 38 Tg yr−1 (30–47 Tg yr−1) of dissolved inorganic carbon through the Strait of Gibraltar into the Atlantic Ocean and an opposite net flux of 3.5 Tg yr−1 (−1.8–9.2 Tg yr−1) of anthropogenic carbon into the Mediterranean Sea.

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