Sulfur speciation and isotopic composition in waters and sediments from river and seawater mixing zones

These investigations showed constancy of sulfate concentrations versus chlorinity. Sulfur isotope composition in sulfates of surface, bottom, and pore waters depended on sulfate contents and salinity.

The dependence was complicated by partial sulfate depletion in pore water due to bacterial sulfate reduction and also by alteration of isotope composition. Surface sediments in mixing zones are characterized by intensive sulfate reduction, great variability of content and isotopic composition of reduced sulfur, and a low mean isotopic fractionation factor of sulfur.