闽江表层沉积物重金属污染分布特征及其来源分析

Distribution and sources of heavy metals pollution in surficial sediments of Minjiang River

为了评价闽江流域表层沉积物中重金属的污染分布特征与影响因素,在沙溪、富屯溪、建溪和闽江中下游采集了39个采样点的表层沉积物,对其进行了重金属含量的检测和地累积指数评价。结果表明,沙溪、富屯溪、建溪和闽江中下游的Pb、Zn、Cr、Ni和Co的平均值低于《土壤环境质量标准》(GB 15618—2008)Ⅱ类标准,但略高于福建土壤环境背景值(富屯溪的Cr平均值和闽江中下游的Co平均值除外),地累积指数评价表明各个重金属元素的Igeo级别在多数采样点为0或1,闽江流域的污染风险整体较小,重金属污染主要表现为点的分布。重金属元素的含量并未出现从上游至下游递增的规律,河流本身对点源污染物有一定的稀释和自净作用。Pb和Zn,Cr、Ni和Co相关关系显著,Pb和Zn主要受城镇建设、交通、生活、工业以及河流动力的影响,采沙场对Zn的影响较大,Cr、Ni和Co的含量同时还与农村生活垃圾、农副产品生产和水电站联系紧密。

In order to investigate the distribution and influencing factors of heavy metals in surficial sediments of Minjiang River,39samples had been collected from Shaxi,Jianxi,Futunxi and the lower reach of Minjiang in this paper.The content of heavy metals in these samples were detected and the geological accumulation index evaluation was performed.The analysis of heavy metals indicated that the average concentrations of Pb,Zn,Cr,Ni and Co in these samples are less than the values of Class Ⅱ soil environment quality standards,and slightly higher than the background values of soil environment in Fujian（except the mean value of Ni in Futunxi）.Based on the geological accumulation index of target heavy metals,most sampling points of Minjiang River were considered as light contamination risk with most Igeoof 0or 1.The distribution of heavy metals pollution in surficial sediments present punctate feature,and the content does not increase from upstream to downstream because of the dilution and self-purification capability the river has.Pb and Zn had significant correlation with each other.The concentrations of Pb and Zn in the surficial sediments of study area were predominantly associated with the urban construction,transportation,livelihood,industry and the power of river,and sand mining has a strong association with Zn.The correlation among Cr,Ni and Co was also remarkable and the contents of them were also closely connected with rural living garbage,agriculture and sideline production and hydrpower input.