Heavy metals in sediments of Yellow Sea and East China Sea: Chemical speciation, distribution, influence factor, and contamination

Metal species and the degree of environmental pollution are related to the hydrogen sulfide (H2S), an important product of early diagenesis that can react with metals to form stable compounds. To investigate the effects of H2S to metals and evaluate metal environment effect in the sediments of the East China Sea (ECS) and Yellow Sea (YS), geochemical characteristic and spatial distribution of nine heavy metals and H2S profile were studied. Higher H2S content and lower metal content was observed in the sediments 10 cm in depth in the North Yellow Sea and the west coast of South Korea. The pollution load index (I-pl) indicates that the southern coast of Shandong Peninsula underwent moderate pollution (I-pl=1) of heavy metals and no heavy metal pollution appeared in other areas (I-pl<1). To some extents, the ecological risk of Cd and As enrichment was moderately severe in all stations. The chance of heavy metal combination to be toxic in ECS and YS during summer was 21%. In addition, correlation between H2S content and metals in both solid and porewater phases was obvious, corroborating important effect of H2S on metal distribution. Moreover, H2S could affect the spatial distributions of heavy metals in porewater directly and be indicative of potential biological effects of combined toxicant groups in the study region.