A national wide evaluation of heavy metals pollution in surface sediments from different marginal seas along China Mainland

Abstract

Sediments, both act as sink and source of heavy metals, played an important role in their global cycle. In coastal ecosystems, heavy metals will be deposited and accumulated in sediments via complex chemical, physical and biological processes and pose potential risks to ecosystems. In the past 3 decades, studies have reported the heavy metal contamination in different ecosystems along China Mainland on local or regional scales, and their concentrations, distribution patterns, sources, as well as ecological risks showed large spatial variabilities. Here, the concentrations of heavy metals in different coastal ecosystems along China Mainland were reviewed from more than 150 published papers. Their distributions patterns, sources and the ecological risks were investigated. As a result, Cr, Cu, Ni, Zn and Pb were the most reported heavy metals with high concentrations observed in nearshore estuaries and coastal bays, which is closely related to the intensive human activities in nearshore areas. Whereas, low heavy metal concentrations were observed in offshore sediments. Source identification suggested that the heavy metals in coastal ecosystems were mainly from phosphate fertilization, atmospheric deposition, weathering and industrial activities. Results from ecological risk assessment indicated that there were high ecological risks in some pollution hot-spots, associated with their high As, Cd, Zn and Pb concentrations.