西江上游有色金属产业集聚区河流沉积物重金属空间分布特征与来源解析

Spatial Distribution and Source Analysis of Heavy Metals in Sediments of the Upstream Xijiang Basin within Nonferrous Metal Accumulation Areas

为研究西江上游有色金属产业聚集区对河流沉积物环境的影响,在西江上游的刁江、龙江、融江和柳江四条河流选取12个采样点,分析测定了10种重金属元素(Cu、Zn、Pb、Cd、As、Cr、Ni、Tl、Sb和Hg)在沉积物中的含量,采用相关分析、主成分分析、聚类分析和Pb同位素示踪技术剖析沉积物中重金属的分布特征与污染来源.结果表明:(1)污染物含量方面,沉积物中w(As)、w(Pb)、w(Cd)、w(Ni)、w(Zn)、w(Cu)、w(Tl)、w(Hg)、w(Sb)、w(Cr)平均值分别为95.42、113.09、4.92、28.03、416.51、27.07、0.75、0.31、34.02、57.58 mg/kg,w(As)、w(Sb)、w(Zn)、w(Pb)和w(Cd)的变化较大,分异显著,受外来源影响较大.(2)空间上,内梅罗指数结果显示,刁江沉积物中重金属污染程度最高,龙江次之,融江和柳江较低.(3)污染物来源方面,As、Pb、Cd、Zn、Cu和Sb具有同源性,与西江上游有色金属聚集区矿产开发有关,Ni、Tl、Hg和Cr具有同源性,与地质背景自然源因子有关;沉积物样品206Pb/207Pb变化范围为1.08~1.19,4条河流沉积物Pb同位素比值与大厂、车河矿石同位素比值接近程度依次为刁江、龙江、融江、柳江.Pb同位素示踪分析结果进一步验证了刁江和龙江沉积物中重金属主要受有色金属采选冶矿业活动影响,融江、柳江沉积物中重金属主要由地质背景自然源因子所致.

This study aimed to investigate how the development of the non-ferrous metals industry impacted sediment deposition in the upstream Xijiang Basin. Twelve sampling sites were selected on four tributaries in the upstream Xijiang Basin,namely,Diaojiang River,Longjiang River,Rongjiang River,and Liujiang River. Contents of Cu,Zn,Pb,Cd,As,Cr,Ni,Tl,Sb and Hg in sediments were measured in the twelve sampling sites,then correlation,clustering,and lead isotope tracing analyses were used to evaluate the distribution and sources of the measured heavy metals in sediments. The results showed that：（ 1） the average contents of As,Pb,Cd,Ni,Zn,Cu,Tl,Hg,Sb and Cr in sediments were 95. 42,113. 09,4. 92,28. 03,416. 51,27. 07,0. 75,0. 31,34. 02 and 57. 58 mg/kg,respectively. The river sediments have been seriously polluted by Cd,As,Zn and Pb,moderately polluted by Hg and Sb,and slightly polluted by Cr,Ni,Cu and Tl.（ 2） From a spatial perspective,the order of pollution degrees of sediments in the four tributaries was Diaojiang,Longjiang,Rongjinag,and Liujiang.（ 3） Regarding the source of contamination,As,Pb,Cd,Zn,Cu and Sb in the sediments were related to the mineral exploitation of nonferrous metal accumulation areas in the upstream Xijiang Basin. Ni,Tl,Hg and Cr in sediments mainly came from the natural geological background. The range of ^206Pb/^207Pb ratio was 1. 08 to 1. 19 in the sediments. The order of similarity between lead isotope ratio in the sediments of the four tributaries and ore of Dachang and Chehe was Diaojiang,Longjiang,Rongjiang,and Liujiang.Lead isotope tracing analysis further revealed that heavy metals in the sediments of Diaojiang and Longjiang Rivers originated from nonferrous mining and smelting activities,and those in Rongjiang and Liujiang Rivers were mainly contributed by the geological background in the sites.