涪江绵阳段表层沉积物重金属污染特征及风险评价

为准确掌握涪江绵阳段表层沉积物重金属的污染特征,分析了7个监测断面表层沉积物中Cd、Se、Mn等19种重金属质量浓度,采用地累积指数法、潜在生态风险评价法和污染负荷指数法评估了沉积物重金属的污染程度及潜在风险。结果表明:涪江绵阳段表层沉积物中Se、Cd、Ba和Hg等元素含量显著超过其土壤背景值,重金属的污染程度依次为Se＞Cd＞Ba＞Hg＞Mo＞Mn;潜在生态风险评价和污染负荷指数评价结果均显示,断面的污染程度排序为楼房沟＞李家渡＞福田坝＞丰谷＞涪江铁路桥＞百顷＞平武水文站断面。楼房沟断面沉积物微观形貌主要为片状或块状,物相主要为石英及少量白云母、方解石和菱锰矿等,与铅锌矿、电解锰渣等主要矿物组成相似,重金属主要来源为尾矿渣在河床的沉积及金属矿开采等外源输入。

Pollution Characteristics and Risk Assessment of Heavy Metals in Surface Sediment from Mianyang Segment of the Fujiang River

In order to accurately grasp the pollution characteristics of heavy metals in surface sediments of Mianyang section in the Fujiang River,19 kinds of heavy metals such as Cd,Se and Mn in surface sediments of 7 monitoring sections were analyzed,and the pollution degree and potential risks of heavy metals in sediments were evaluated by using geoaccumulation index method, potential ecological risk assessment and pollution load index method. The results showed that Se, Cd, Ba and Hg in surface sediments of Mianyang section in the Fujiang River significantly exceeded their soil background values,and the pollution degree of heavy metals was Se > Cd > Ba > Hg > Mo > Mn in turn. The potential ecological risk assessment and pollution load index assessment were shown as Loufanggou > Lijiadu > Futianba > Fenggu > Fujiang Railway Bridge > Baiqing > Pingwu Hydrological Station. The microscopic morphology of the sediment on the section of Loufanggou was mainly sheet or block,and the physical phase was mainly quartz and a small amount of muscovite,calcite and rhodochrosite,which was similar to the results of major mineral phases such as lead zinc ore and electrolytic manganese slag. The main source of heavy metals was the deposition of tailings in the river bed and the external input of metal ore mining.