Pollution characteristics and risk assessment of heavy metals in the surface sediments of Dongting Lake water system during normal water period

Abstract

In order to study the characteristics and ecological risks of heavy metal pollution in Dongting Lake, 24 sediment cores were collected in August, 2017. The content characteristics and the pollution status of heavy metals in the study area were analyzed by the method of Igeo, RI and mPEC-Q, and the interrelation and source of heaty metals were evalutated by CA and PCA. The results showed that the concentrations of heavy metals in the surface sediments followed the order of Cr > Pb > Cu > As > Cd > Hg, and the contents of Hg, Cr, Cd, Pb, Cu were 7.0, 2.0, 9.3, 2.2, 2.3 times greater than the background values, respectively. The results using the geo-accumulation index and the potential ecological risk assessment indicated that Cd and Hg were considered as the dominant pollutants. The RI values followed the order of Cd > Hg > Cu > Pb > As > Cr and the mean value of mPEC-Q was 0.43, indicating that the sediments in all of the sampling sites had a 15%-29% probality of toxcity. Source analysis showed that As, Pb, Cd and Cu were homologous and mainly came from the industrial wastewater of the “Four-rivers” basin.

Keywords

• dongting lake water system
• sediments
• heavy metals
• pollution characteristics
• risk assessment