Investigation on the distribution and potential ecological risk of heavy metal in the sediments from typical electrical industrial zone

In order to investigate heavy metals contamination status in a river of a typical electrical equipment industrial area, Ronggui, Foshan, 12 sediment simples were sampled for analyzing Cu, Pb, Zn, Cd, Cr, As and Hg. The index of geoaccumulation (I _geo) and potential ecological risk index (PERI) were then employed to evaluate the pollution degree of heavy metals in the sediments. The spatial trends results indicate that the sediments in sampling sites have been severely contaminated and the concentrations of Cu, Pb, Zn, Cd, Ni, Cr, As and Hg in the samples ranged from 70.1-3 525.5, 378.1-2 994, 130.9-4 791.5, 65.8-374.7, 19.2-56.8, 0.5-4.9, 0.3-2.1 mg·kg ^-1, respectively. The descending order of pollution degree of metals was: Cd>Cu>Zn>Cr>Hg>Pb>As, and the average I _geo values of Cd and Cu reached severely contamination grade. Similarly, the potential ecological risk intensity caused by different metals was: Cu>Hg>Cd>Cr>Pb>Zn>As, and the average PERI values of Cu, Hg and Cd reached strong grade. Distribution profiles of heavy metals in vertical direction were different with depths. The concentrations of Cu, Zn, Pb, Hg and As reduced from the bottom to the upper layers. The high ecological risk element Cd showed a slight increase in the surface layer, whereas the concentration of Cr steadily increased with the reducing of depth.