都柳江急流-深潭-河滩系统底质重金属分布与污染评价

Evaluation of Heavy Metal Pollution on Riffle-Deep Pools-Sand Bank Systems in Different Section Duliu River

为全面了解贵州省境内都柳江急流-深潭-河滩系统底质重金属含量分布及污染水平,在都柳江上中下游分别选取3个典型河段,通过野外采样和实验室分析,对7种重金属含量进行环境状况评价。结果表明:急流-深潭-河滩系统底质重金属含量水平变化趋势基本一致,在这个系统的三个结构系统中重金属含量的顺序依次为w(Zn)>w(Cr)>w(As)>w(Pb)>w(Cu)>w(Cd)>w(Hg);综合污染指数评价方法(P)表明都柳江流域处于轻度污染到中度污染状态;潜在生态危害指数评价方法(RI)表明都柳江处于轻微潜在生态危害到强潜在生态危害等级;地累积指数方法(Igeo)表明As污染较为严重。三种指数评价方法均表明都柳江上游急流和深潭处(JL上和ST上)、下游河滩处(HT下)受污染程度明显大于其它采样点。综合污染指数评价方法直观但强调统一性,潜在生态风险评价方法考虑较综合但主观性强,地累积法简便但具有局限性,故对底质中重金属的环境影响评价需要用多种方法进行综合比较以减少误差提高准确度,本文研究结果增进了都柳江流域底质重金属污染状况的了解。

In order to investigate the distribution of heavy metals pollution levels in sediment of Duliu River,Guizhou Province,a total of 27 samples were sampled from the typical riffle-deep pools-sand bank systems of the river,and the contents of seven heavy metals were measured for the environmental assessment. The results showed that the heavy metals in sediment of riffle-deep pools-sand bank system basically presented the same trends,which is w（Zn）〉 w（Cr） 〉w（As）〉 w（Pb）〉 w（Cu）〉 w（Cd）〉 w（Hg）.Nemerow index（P） indicated the river basin to be from slight to moderate pollution. Potential ecological risk index assessment method（RI） revealed the river ecological risk level to be from light to strong potential,and Muller index（Igeo） reflected more serious pollution. The above-mentioned evaluation methods mirrored the considerable pollution status in the jet and pool of upstream,and the pollution status of downstream flood was more severe than the section of the river. Among the evaluation methods,Nemerow index was intuitive with the unity,and the potential ecological risk index was more comprehensive but subjective. Muller index method was simple. Therefore,the assessment of the heavy metals in sediment needs to be integrated with a variety of methods. This investigation provided more information on heavy metal pollution in sediment in Duliu River.