Concentrations of seven heavy metals in the coastal sediments of the northern Dongying City were measured. The spatial distribution and sources of heavy metals were discussed and the ecological risk was assessed using sediment quality guidelines (SQGs) and the potential ecological risk index (PERI). The concentration ranges of Hg, As, Pb, Cd, Cr, Cu, and Zn were calculated as 0.005-0.092, 3.44-10.41, 6.59-19.00, 0.50-1.10, 32.42-60.25, 1.72-23.78, and 31.13-69.96 mg·kg-1, respectively. Higher metal concentrations were observed at site S10, which was close to the mouth of Tiaohe River and contained plenty of organic matter, silt, and clay. Principal component analysis (PCA) indicated that As and Pb in the sediments were derived from natural weathering processes, while other metals were mainly attributed to anthropogenic sources, i.e., land-sourced pollutants transported by runoff. Concentrations of As, Cd, Cr, and Cu at some sampling sites exceeded the threshold effect level (TEL) stated in the SQGs implying occasional harmful effects on biological life. PERI showed that the sediments in this area generally had a medium risk, except sites S10, S3, and S9 posing a considerable risk, and that Cd and Hg were the major contributors to the ecological risk. It is necessary to take effective measures to control heavy metal fluxes from rivers around this area and to reduce the risk.
Keywords: distribution; ecological risk; estuary; heavy metals; sediment; source.