Sources of Freshwater Components in Western Part of the Bering Sea According to Isotope (δ18О, δD) Data

Abstract

The isotope parameters and sources of freshwater components for the subsurface, intermediate, and deep water of the western Bering Sea were estimated using the isotope (δ¹⁸О, δD) data for 177 seawater samples. We show that subsurface, dichothermal and, partially, intermediate water (<1000 m) are freshened by regional precipitation. For these waters, the next equations of relations between delta and salinity values were obtained: δ¹⁸О = [0.390 ± 0.018]S – 13.521 ± 0.613 and δD = [3.07 ± 0.08]S – 107 ± 2.74. Deeper (1000–2500 m) water is also freshened by precipitation but from the more southern region (≈40°–45° S). The deepest water (2800–4300 m) retain their isotope signal obtained via freshening by Antarctic glacier ice meltwater. The distribution of isotope parameters with the depth shows that vertical mixing at depths of ≈1000–2500 m takes place. This process should influent the redistribution of nutrients, dissolved oxygen, organic matter, and other components in water of the western Bering Sea. The isotope composition of water passing into the Arctic Ocean halocline (S = 33.1) from the Bering Sea are δ¹⁸О = –0.61‰ and δD = –5.4‰.