Ecological risk by heavy metal contents in sediments within the Wei River Basin, China

The Wei River is the largest tributary of the Huang River, which is the second largest river in China. This study aimed to determine pollution and risk assessment of heavy metals, including chromium (Cr), lead (Pb), zinc (Zn), arsenic (As), mercury (Hg), and cadmium (Cd), in 12 selected stations of the Wei River Basin, Northwest China. Results indicated that the pollution and potential risk in Weijiabao are more severe than the other 11 cross sections. The concentrations and potential ecological risk of Pb and Hg and Cr, Pb, Zn, As, and Hg were observed in moderately contaminated and considerable risk levels given industrial wastewater discharge, correspondingly. For the single element, the relative contaminated status and potential risk levels for Cr, Pb, Zn, As, and Hg were Zn > Hg > Cr > Pb > As and Hg > Pb > As > Cr > Zn, respectively. The Cr in sediments may derive from agricultural activities given the utilization of chemical fertilizers, whereas Pb, Zn, and As may derive from industrial wastewater and sewage sludge. Metal melting wastewater in the upper reach and paper mill and textile process wastewater in the middle reach of the Wei River should be disposed of and should satisfy the corresponding criteria of the Integrated Wastewater Discharge Standard (GB8978-2002). Furthermore, a scientific application of chemical fertilizers in the Jing and Beiluo Rivers should be implemented in the reach.