Spatial distribution, ecological risk assessment and source identification for heavy metals in surface sediments from Dongping Lake, Shandong, East China

• Metal concentrations show typical spatial heterogeneity due to pollution.
• Dongping Lake is significantly polluted by As, Cd and Hg.
• Heavy metals pose moderate to considerable ecological risk to Dongping Lake.
• Industrial and agricultural sources are mainly responsible for the metal pollution.
• Dawen River is the primary vector of heavy metal load.

Surface sediment samples collected from 18 sites in Dongping Lake were analyzed for selected heavy metals including As, Cd, Cr, Cu, Hg, Pb, and Zn to determine their spatial distribution, source, and potential ecological risks. The enrichment degree of the studied metals decreased in the order of Cd > Hg > As > Pb > Cu > Cr > Zn, and the average concentrations of Cd, Hg and As were 3.70, 3.69 and 3.37 times their background values. With the exception of Cd, the concentrations of heavy metals decreased progressively from the southeast to the north and west within the lake. Based on the enrichment factor (EF) and the potential ecological risk index (PERI), As, Cd and Hg were the heavy metal contaminants of most concern in surface sediments. Moreover, referencing to the results of multivariate statistical analyses, we deduced that anthropogenic As and Hg were mainly from industrial and mining sources within the Dawen River watershed, whereas, Cd originated from agricultural sources.