广东茂名主要水系表层沉积物重金属风险评估及源解析

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

为了解广东茂名主要水系表层沉积物重金属的空间分布特征及其污染来源,合理评价研究区域沉积物重金属的生态风险,对茂名市8条河流和3座水库表层沉积物中重金属(As、Hg、Cd、Co、Cr、Cu、Mn、Ni、Pb和Zn)含量进行分析.采用地累积指数、潜在生态风险指数和潜在生物毒性效应评估重金属的生态风险;使用主成分分析和正定矩阵因子分解模型解析重金属的来源.结果表明,表层沉积物中ω(Zn)(147.56mg·kg^(-1))和ω(Hg)(0.20mg·kg^(-1))水平较高,分别超背景值3.72倍和2.25倍.Cd、Co、Cu、Mn、Ni和Zn含量水平在空间分布上表现为:北部>中部>西部>东南部.地累积指数结果显示Zn为偏中度污染,76.6%采样点的Hg为轻度-偏重度污染,其余元素整体上为无-轻度污染.潜在生态风险和潜在生物毒性评估结果均表明高州水库潜在生态风险指数和毒性效应较其他水系高,且Hg为主要贡献元素.主成分分析和正定矩阵因子分解模型提取的3个因子分别代表自然源、农业面源和工业源.因此,为降低沉积物中重金属带来的健康危害,应注重对Hg的防控治理.

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(∑TUs).The sources of heavy metals were analyzed via correlation,principal component analysis(PCA),and positive matrix factorization(PMF).The results showed that theω(Zn)(147.56 mg·kg^(-1))andω(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.