Metals Pollution and Ecological Risk Assessment of Sediments in the Poyang Lake, China

The concentrations of several metals and their geochemical species in surface sediment from Poyang Lake main channel and its tributary entrance were analyzed. Results showed that the concentrations of Cu (28.1-213 mg/kg), Zn (82.6-257 mg/kg), Pb (49.8-81.4 mg/kg) and Ni (33.5-56.0 mg/kg) were higher than the background values, while Cd (0.15-0.81 mg/kg) was lower. Zn, Cu and Ni were predominately bound to residual fraction. The content of Pb in the Fe-Mn oxides fractions was considerable. And Cd had highest concentration of exchangeable and carbonate fractions. The geoaccumulation index showed that the sediments were unpolluted with Cd, moderately polluted with Pb, Zn and Ni, while moderately to heavily polluted by Cu. Principal component analysis indicated that Ni was mainly lithogenic in origin and Cu, Pb, Zn and Cd were influenced by anthropogenic contamination. The concentrations of Cu, Pb and Zn were above the threshold effects level (TEL) but below the probable effects level (PEL), Cd was below TEL, whereas the contents of Ni were above PEL. The potential ecological risk index showed Cu posed moderate ecological risks, Cd, Ni, Pb and Zn posed low ecological risk. The general ecological risk belonged to the high risk.