Distribution, sources and ecological risk assessment of heavy metals in the surface sediments of Lake Liuye and its adjacent waters, China

Surface sediment samples were collected at 13 sites from Liuye Lake and its adjacent waters. Heavy metals in samples were extracted by a total digestion technique and then the concentrations of Ni, Cr, Cd, Pb, Cu, Zn and As were measured by using ICP-MS. Spatial distribution, source and ecologic risk assessment of heavy metals in the sediments were investigated based on concentrations determined. The results showed that the average concentrations of Cr, Ni, Cu, Zn, As, Cd and Pb were 62.3, 40.6, 32.8, 223, 16.9, 0.74 and 31.5 mg kg−1, respectively, which are higher than background concentrations. The enrichment factors further indicated that the heavy metals in sediments reached to the level of deficiency to minor contamination. Toxicity assessment based on the SQGs suggested that these heavy metals might pose a detrimental effect on benthic organisms. The average toxic units of heavy metals declined as the following order Ni > As > Zn > Cr > Pb > Cd > Cu, indicating toxic effect was dependent on both their concentrations and relative toxicity. The risk index values of heavy metals ranged from 40 to 200 and the heavy metals at the sites of S3–S13 even reached to the grade of moderate risk. The results of Pearson’s correlation coefficient analysis, principle component analysis and dual hierarchical clustering analysis indicated that the distribution of Cr, Cu and Pb was related to discharge of wastewater. Besides, wastewater of nickel plating plate and fertilizer might be the sources of Ni and Zn, respectively. In addition, atmospheric deposition was regarded as the main source of As and the source of Cd might be related with industrial wastewater. Hence, it is advised that further management and pollution control should be implemented for the seven heavy metals in Liuye Lake and its adjacent waters.