Comparison of sulfate reduction rates associated with geochemical characteristics at the continental slope and basin sediments in the Ulleung Basin, East Sea

Abstract

In conjunction with geochemical characteristics, rate of sulfate reduction was investigated at two sediment sites in the continental slope and rise (basin) of the Ulleung Basin in the East Sea. Geochemical sediment analysis revealed that the surface sediments of the basin site (D2) were enriched with manganese oxides (348 μmol cm-3) and iron oxides (133 μmol cm-3), whereas total reduced sulfur (TRS) in the solid phase was nearly depleted. Sulfate reduction rates (SRRs) ranged from 20.96 to 92.87 nmol cm-3 d-1 at the slope site (M1) and from 0.65 to 22.32 nmol cm-3 d-1 at the basin site (D2). Depth integrated SRR within the top 10 cm depth of the slope site (M1; 5.25 mmol m-2 d-1) was approximately 6 times higher than that at the basin site (D2; 0.94 mmol m-2 d-1) despite high organic content (>2.0% dry wt.) in the sediment of both sites. The results indicate that the spatial variations of sulfate reduction are affected by the distribution of manganese oxide and iron oxide-enriched surface sediment of the Ulleung Basin.