ALKALINITY AND CARBON BUDGETS IN THE MEDITERRANEAN-SEA

Alkalinity and salinity are linearly correlated in the waters of the m ost western part of the Mediterranean Sea, Nevertheless, the specific alkalinity of the saltier Mediterranean waters is higher than that of the less saline water of Atlantic origin. This may be explained by alk alinity input from rivers and the Black Sea. In the hypothesis of a st eady state, the relationship between alkalinity and salinity permits c alculation of the net flux of alkalinity between the Mediterranean Sea and the Atlantic Ocean, provided the water budget of the Mediterranea n is known. The sources (rivers and the Black Sea) and sinks (seafloor ) of alkalinity in the Mediterranean balance the net alkalinity transp ort into the Atlantic, if the water deficit of the Mediterranean is 2. 2 x 10(12) m3 yr-1 or 88 cm yr-1 per unit area. The budget of carbon i n the Mediterranean Sea is more difficult to assess as the sources and sinks are numerous and not well-documented. There is particularly a l ack of data on the seasonal variations in the inorganic and organic ca rbon concentrations in the region of the strait of Gibraltar and on th e partial pressure of CO2 in surface water of the Mediterranean Sea. I t appears nevertheless that there is an important flux of inorganic ca rbon from the Mediterranean to the Atlantic due to the supply of carbo n by the rivers and the Black Sea and to the transformation of 40% of the organic carbon entering the Mediterranean in inorganic carbon. Mor eover, the Mediterranean is likely a sink for the atmospheric carbon.