Assessing the impacts of differential depositional settings and/or anthropogenic perturbations on sulfur and iron diagenesis in sediments of the Bohai Sea and North Yellow Sea.

Natural processes and human activities exert important impacts on elemental cycling in coastal sediments, which has not been well documented. Sediments in the Bohai Sea and North Yellow Sea were investigated to assess the impacts of the Yellow River inputs and/or anthropogenic perturbations on diagenesis of iron and sulfur. Labile iron (0.5 M HCl-extractable iron) in the sediments is low due to iron-poor nature of source materials. Dynamic regimes and low availability of labile organic carbon (OC) result in relatively low sulfide contents in deltaic sediments. However, low but continuous supply of labile OC exported from an anthropogenically impacted bay could substantially elevate sulfide burial in sediments near the bay. Neither offshore oil exploitations nor frequent algal blooms in the seas have detectable influences on iron and sulfur diagenesis in the sediments. The sediments are capable of quickly consuming porewater sulfide by reaction with reactive iron under the current conditions. [Display omitted] • Availability of labile organic carbon is driving factor of sulfate reduction. • Labile iron is low in the sediment due to iron-poor nature of source materials. • Human perturbations have no significant impact on sulfur and iron diagenesis. • The Yellow River estuary exerts important influences on sulfur cycling. [ABSTRACT FROM AUTHOR]