Stable sulfur isotopes indicate net sulfate reduction in near-surface sediments of the deep Arabian Sea

Pockmark activity inferred from pore water geochemistry in shallow sediments of the pockmark field in southwestern Xisha Uplift, northwestern South China Sea

“…Microbial sulfate reduction is the main reason for the 34 S enrichment of sulfate in the pore waters of marine sediments (Böttcher et al, 2000;Ku et al, 1999). The sulfur isotope fractionation imparted during microbial sulfate reduction is controlled by a number of factors, including the sulfate reduction rate, sulfate concentration, organic matter oxidation pathway, and the sulfate reducer species (Briichert, 2004).…”

“…Because the d 13 C value of organic matter is distinct from that of methane and there is little carbon isotopic fractionation during the transformation from organic matter and methane to DIC (Gieskes et al, 2005;Roberts et al, 2010), the carbon isotopic composition of the DIC pool is a critical parameter for fingerprinting the carbon source and understanding the carbon biogeochemical cycling (Chen et al, 2004(Chen et al, , 2010Feng and Roberts, 2010;Yang et al, 2008 (Harrison and Thode, 1958). As a result, the sulfur isotopic compositions of dissolved sulfate in pore waters have been widely used as an indicator of the occurrence of bacterial sulfate reduction (Böttcher et al, 2000;Feng and Roberts, 2011;Jørgensen, 1979). In addition, sulfate-reducing bacteria are able to generate high sulfur isotope fractionation; the maximum sulfur isotope fractionation between sulfate and sulfide was up to 72& (Wortmann et al, 2001).…”

Pore-water sulfate concentration profiles of sediment cores from Krishna-Godavari and Goa basins, India

“…Depth integrated sulfate reduction rate (J) in Goa varies from 0.011 to 0.942 nmol cm -2 day -1 . Böttcher et al (2000) also recorded very limited sulfate reduction from the Arabian Sea sediments at 3186-4426 m water depth. Average TOC% (0.54 to 0.66%) recorded in the present study is comparable with that recorded by Böttcher et al (2000).…”

“…Böttcher et al (2000) also recorded very limited sulfate reduction from the Arabian Sea sediments at 3186-4426 m water depth. Average TOC% (0.54 to 0.66%) recorded in the present study is comparable with that recorded by Böttcher et al (2000). Although Arabian Sea has much higher primary productivity than the Bay of Bengal, the organic carbon (C org ) flux is marginally higher in the latter (Ramaswamy and Nair, 1994;Gauns et al, 2005).…”

Iron dynamics in a subtropical estuarine tidal marsh: effect of season and vegetation

“…This depth was chosen because the most dramatic impacts of seasonal change would be expected to occur in surface sediments (Böttcher et al 2000, Kostka et al 2002a). Cores were taken using polycarbonate corers (internal diameter: 5 cm; length: 50 cm) that were immediately capped at both ends following sampling and placed in vacuumized plastic bags.…”