[Risk Assessment and Source Analysis of Heavy Metal Pollution in Surface Sediments from Major River Systems in Maoming City, Guangdong Province].

Abstract

In order to understand the spatial distribution and sources of heavy metals in surface sediments of MaoMing city and to reasonably evaluate the ecological risk of heavy metals in sediments of the study area, the contents of heavy metals (As, Hg, Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn) in surface sediments of eight rivers and three reservoirs were detected, and the risks of heavy metals were assessed using the geo-accumulation index (Igeo), potential ecological disk index (RI), and potential adverse biological impacts (ΣTUs). The sources of heavy metals were analyzed via correlation, principal component analysis (PCA), and positive matrix factorization (PMF). The results showed that the ω(Zn) (147.56 mg·kg-1) and ω(Hg) (0.20 mg·kg-1) were 3.72 and 2.25 times the background value, respectively, and the spatial distributions of Cd, Co, Cu, Mn, Ni, and Zn were in the order of northern>central>western>southeast. The geo-accumulation index results showed that Zn was at a moderate pollution level, 76.6% of the sampling sites of Hg were at a light-heavy pollution level, and other heavy metals were at a non-light pollution level. The results of potential ecological risk and potential adverse biological impacts indicated that the potential ecological risk index and toxicity effect of Gaozhou Reservoir were higher than those of other rivers, and Hg was the major contributor to heavy metal pollution. The three factors extracted from principal component analysis and positive matrix factorization represented natural sources, agricultural sources, and industrial sources, respectively. Therefore, in order to reduce the health hazards caused by heavy metals in sediments, a prevention and control system for the Hg element should be established.