Source identification and risk assessment based on fractionation of heavy metals in surface sediments of Jiaozhou Bay, China

Highlights: • The contents of heavy metals increased by 2–5 times than those in 2000s. • Heavy metals in sediments of Jiaozhou Bay were mainly in low to medium risks. • The potential toxicity of Cd in Jiaozhou Bay should be paid more attention. • Three types of anthropogenic activities were identified based on labile heavy metals. - Abstract: To identify sources and evaluate ecological risks of heavy metals in sediments of Jiaozhou Bay, contents and chemical fractions of Cd, Cr, Cu, Pb, Zn, Ni, Sb and Sn were studied. Results suggested that higher metal contents appeared at inner bay and near marine dumping area. Labile fractions of heavy metals accounted for 0.5–77% (~36%) of total contents indicating their significant anthropogenic sources. The enrichment levels of Cd and Sb were relatively higher. Cu, Ni, Cd and Zn were at low to medium risks. Cr, Pb, Sn and Sb were at no or low risks. Total contents of heavy metals were mainly controlled by natural sources, while anthropogenic inputs were important sources of labile fractions of heavy metals in sediments of Jiaozhou Bay with industrial and domestic activities as main contributors for Cu, Pb, Zn, Cr, Ni and Sn, and agricultural activities for Cd and regional coal combustion for Sb.