Carbonate system and acidification of the Adriatic Sea

Although the marginal seas represent only 7 % of the total area of the ocean, CO2 fluxes are important for the carbon budget, exposing them to the intense process of anthropogenic ocean acidification. The Adriatic Sea is currently a CO2 sink (−0.5 to −1 mol C m−2 y−1) with an annual flux comparable to the net sink rates in the NW Mediterranean. Based on a comparison of two winter cruises carried out in the 25-years interval between 1983 and 2008, an acidification rate of 0.003 pHT units y−1 was estimated in the northern Adriatic which is similar to the Mediterranean open waters (with recent estimations of −0.0028 ± 0.0003 pHT units y−1) and the surface coastal waters (−0.003 ± 0.001 and − 0.0044 ± 0.00006 pHT units y−1). The computed Revelle factor for the Adriatic Sea (approximately 10) indicates that the buffer capacity is rather high and that the waters do not appear to be particularly exposed to acidification. Total alkalinity (TA) in the Adriatic (2.6–2.7 mmol kg−1) is in the uppe...