乐安河沉积物重金属污染评价与来源解析

Pollution assessment and source apportionment of heavy metal pollution in sediments of Le’an River

河流沉积物中重金属污染形势严峻,对流域生态系统造成了明显威胁.为辨识鄱阳湖重要支流--乐安河中重金属的环境特征,采集了76份乐安河沉积物样品,检测了16种重金属元素,发现所有重金属的质量分数均值超过中国水系沉积物背景值,其中Cd、Cu和Hg分别超标22.00、13.13和9.67倍.生态风险评价发现,乐安河流域的生态风险水平处于中等风险或以上水平,Cd的生态风险最高.正定矩阵因子分解(PMF)源解析结果表明乐安河沉积物重金属主要源于金矿采选的混合源、铜矿区尾矿源、铅锌矿采选源、化肥农药源和自然源等,其中采矿活动相关来源的贡献率总和达到67%,说明采矿活动是乐安河流域重金属污染的主要成因.

Increasing heavy metal pollution in river sediment poses a significant threat to the health of watershed ecosystem. To characterize heavy metal pollutions in the Le’an River, an important tributary of Poyang Lake, sediment samples were collected from 76 sites along the Le’an River and concentrations of 16 heavy metals were determined. The average concentrations of heavy metals were found to have exceeded background values. Cd, Cu and Hg were found to be 22.00, 13.13 and 9.67 times their respective standard values. Ecological risk of the Le’an River was found to be above middle level Cd showed the highest risk. PMF model was used to apportion sources of heavy metal pollution in sediments. Five main sources were found: mixed source consisting of soil materials and gold mining, copper mine tailings, lead-zinc mining, chemical fertilizers and geogenic sources. The summed relative source contribution ratios of heavy metals from mining-related sources was 67%, suggesting that mining activity was the main cause of heavy metal pollution of the Le’an River.