Heavy metals in surface sediments along the Weihai coast, China: Distribution, sources and contamination assessment

The Weihai coast is a representative zone with fifty-year history of mariculture in China. Algae and shellfish are the main cultured species, other species including fish and sea cucumber are also cultivated. In this study, heavy metals in surface sediments, sampled along the Weihai coast during May yearly between 2009 and 2013 were investigated in terms of their contents and spatiotemporal variation. The contents of Zn, Cr, Cu, Cd, Pb and As showed different spatiotemporal variations and ranged between 11.6 and 115.9, 4.15-51.3, 5.2-21.9, 0.02-0.33, 6.0-54.2, and 2.9-18.7μgg^-1, respectively. Among them, Zn, Cu and As declined during the five years. Ecological risk assessment revealed that Cd posed a moderate risk, as compared to other five elements, which were relatively low risks in surface sediments. Source analysis revealed that Zn, Cr and Cd were mainly from lithogenic contribution, while As was likely from anthropogenic discharges.