Hydrodynamically-driven distribution and remobilization of heavy metals in surface sediments around the coastal area of Shandong Peninsula, China.

Abstract

Heavy metals (HMs) are considered a major pollutant of the surface sediments of the continental shelf. However, there remains little in-depth research on their fate in the ocean, and particularly on their abundance in sediments and the water column and the underlying drivers. This study examined the concentrations of HMs (Cu, Zn, Cr, Pb, Cd, and As) in surface sediments and suspended particulate matter (SPM) around the coastal area of Shandong Peninsula, China. The division of the sedimentary environment and influencing factors were also analyzed using multivariate statistical analysis Fuzzy c-means (FCM) cluster and Non-Linear Mapping (NLM). The study attempted to understand the distribution and remobilization of HMs in the shallow marginal sea using multi-disciplinary approaches, including satellite remote sensing and numerical simulation. The results showed higher HMs in the surface sediments in Weihai Bay (Zone I) than in the junction of the Chengshantou Cap (Zone III) and north of Wei Bay (Zone II). In addition, the results suggested that Cu, Zn, Cr and Pb originated from natural weathering, with their spatial distributions in the three zones highly regulated by sediment grain size, total nitrogen (TN), and total carbon (TC). In contrast, Cd and As originated from anthropogenic contamination (e.g., industrial discharges and aquaculture) in Zone I. HMs (except As) were influenced by terrigenous total organic carbon (TOC) in Zone III. The results of this study suggest that the difference in sediment re-suspension intensity has an important influence on the distribution of HM concentrations in the north Yellow Sea. This study can act as a reference for understanding the fates and source-sink processes of HMs in offshore sediments. The coupling behaviors and microscopic suspension properties of HMs in surface sediments and SPM require further investigation.