Stable isotope composition of dissolved sulfate and hydrogen sulfide in the Black Sea

The stable isotope ratio of sulfur (³⁴S/³²S) in dissolved sulfate and hydrogen sulfide was measured for 20 water samples from two deep hydrocasts from the south-central Black Sea. The isotope ratio of total reduced sulfur was also measured for surface sediment collected below each hydrocast. The range in the δ³⁴S measurements for sulfate was +18.20 to $\text{+20.17‰}$ and for hydrogen sulfide ?38.71 to $\text{?4.85‰}$. The distribution pattern for δ ³⁴S in both sulfate and sulfide appears to be the result of in situ sulfate reduction.