Abstract
The oxygen (
18O/
16O) and hydrogen (D/H) isotopic ratios have been measured at eight stations in the Black Sea and the Sea of Marmara. Analyses revealed that the O and H isotopic characteristics of the deep water were similar [(δ
18O = −1.65‰ (σ = 0.27), δD = −14.29‰ (σ = 2.19)] across the entire width. The upper oxic layer however exhibited a high degree of variability related to high rates of evaporation during the summer and probable mixing during the winter. Using an evaporation model it can be calculated that the stable O and H isotopic composition of the Black Sea are relatively insensitive to large variations in the fluxes and isotopic compositions of the inputs. Based on this model it is estimated the (δ
18O of the Black Sea prior to Mediterranean influence was approximately −3.3‰ (SMOW-standard mean ocean water). The upper oxic layer could have reached an O and H isotopic composition close to the present day approximately 10 years after the initiation of Mediterranean flow into the Black Sea. Continued changes in the O and H isotopic composition of the upper layer occurred until the lower anoxic portion of the Black Sea reached a steady-state composition, approximately 1000 years after initiation of Mediterranean flow.
