δ18O versus δD values in the Black Sea water (1) and its possible sources. The LBC composition is close to seawater of the Marmara Sea (depth >50 m) (2)  and the East Mediterranean Sea (3) . Fresh water input (4) consists of river runoff (5) and precipitation (6–8) which are modified by evaporation (9). River runoff is presented by average isotope composition of the lower part Danube River (5) , data on annual average precipitation composition (6) are from , data on warm months (7) and cold months (8) are from . Evaporation line is calculated from water mass balance in the Black Sea (see details in text). SMOW isotope composition (10) is also shown.