Occurrence, distribution and ecological risk assessment of heavy metals in surface sediments of Nanfei River, China

Abstract

In order to grasp the status of contamination of heavy metals pollution in the surface sediment of Nanfei River, the pollution characteristics of eight heavy metals (Cd, Cr, Cu, Pb, Zn, As, Hg, Ni) were analysed and their potential ecological risks were evaluated. The result showed that, the concentrations of Cd, Cu, Zn were 4.45, 1.23, 3.27 times than the corresponding background values, respectively. The pH value and the concentration of total organic carbon (TOC) have good correlation with the heavy metals as well as the heavy metals have with each other. There are significant correlations for TOC-Cr, TOC-Ni, TOC-Cu, TOC-Hg, Cr-Ni, Cr-Pb, Ni-Cu, Zn-Pb, As-Pb, As-Hg. The pollution degree of the eight heavy metals was: Zn > Hg > Cu > Cd > As > Cr > Pb > Ni, while the order of potential ecological risk of the heavy metals was found to follow the sequence: Cd > Hg > As > Cu > Zn > Pb > Ni > Cr. The spatial distribution feature suggested that the agricultural sector showed relatively low ecological risk and the ecological risk of urban section was higher. This is the first systematic report concerning the content, distribution and potential ecological risk of heavy metals in the surface sediment of Nanfei River.