Ecological risk of heavy metals in sediments of the Luan River source water.

Distribution and characteristics of heavy metals enrichment in sediment were surveyed including the bio-available form analyzed for assessment of the Luan River source water quality. The approaches of sediment quality guidelines (SQG), risk assessment code and Hakanson potential ecological risk index were used for the ecological risk assessment. According to SQG, The results show that in animal bodies, Hg at the sampling site of Wuliehexia was 1.39 mg/kg, Cr at Sandaohezi was 152.37 mg/kg and Cu at Hanjiaying was 178.61 mg/kg exceeding the severe effect screening level. There were 90% of sampling sites of Cr and Pb and 50% sites of Cu exceeded the lowest effect screening level. At Boluonuo and Wuliehexia, the exchangeable and carbonate fractions for above 50% of sites were at high risk levels and that for above 30% of sites at Xiahenan and Wulieheshang were also at high risk levels. Other sites were at medium risk level. Compared to soil background values of China, Hg and Cd showed very strong ecological risk, and the seven heavy metals of Hg, Cd, Cu, As, Pb, Cr, Zn at ecological risk levels were in the descending order. The results could give insight into risk assessment of environmental pollution and decision-making for water source security.