湘江流域长沙段沉积物中重金属污染及来源

Pollution and Sources of Heavy Metals in Sediments of Changsha Section of Xiangjiang River

选取受采矿污染严重的湘江长沙段为研究对象,对其流域沉积物中的重金属污染状况和来源进行研究。采用ICP-MS分析沉积物中Cr、Mn、Fe、Co、Ni、Cu、Zn、As和Cd的含量,采用富集因子评价重金属污染,通过Pearson相关分析、层次聚类分析和主成分分析研究重金属的来源。结果发现湘江长沙段地表水中Mn的最大值和平均值、As的最大值都超出了中国地表水环境质量的I级标准。沉积物中重金属平均含量由高到低依次为Fe>Mn>Zn>Cr>As>Cu>Ni>Co>Cd,其中Cr、Ni、Zn、As、Cd的平均含量均超过了TEC值。采样点S5附近Mn、Fe、Co、Zn、As和Cd元素含量较其他采样点高。来源分析发现Mn、Zn、As和Cd可能与锌矿和锰矿的开采及冶炼废水的排放有关,Fe、Cu、Ni和Co可能来源于自然存在,Cr可能与工业废水的排放有关。结合富集系数EF分析发现,Mn、Cd、Zn、As污染最为严重,这四种元素的污染主要受人为活动的影响。

A mine-impacted Changsha section of Xiangjiang River is selected as the research object.The pollution status and sources of heavy metals in sediments of the basin are studied.The levels of Cr,Mn,Fe,Co,Ni,Cu,Zn,As and Cd in sediments are determined using inductively coupled plasma mass spectrometry.Enrichment factor is used to evaluate heavy metal pollution.The sources of heavy metals are studied by Pearson correlation analysis,hierarchical cluster analysis and principal component analysis.The results show that the maximum value and average value of Mn and the maximum value of As in the surface water of Changsha section of Xiangjiang River exceed the Level I standard of surface water environmental quality in China.The average content of heavy metals in sediments in descending order is Fe>Mn>Zn>Cr>As>Cu>Ni>Co>Cd,and the average content of Cr,Ni,Zn,As and Cd exceeds the TEC values.The contents of Mn,Fe,Co,Zn,As and Cd elements near sampling site S5 are higher than those at other sampling sites.Source analysis shows that Mn,Zn,As and Cd might be related to the mining of zinc ore and manganese ore and the discharge of smelting wastewater,whereas Cr might be due to the discharge of industrial wastewater,and Fe,Cu,Ni,and Co might be naturally occurring.Enrichment coefficient EF analysis shows that Mn,Cd,Zn and As are the most polluted elements,and the pollution of these four elements is mainly affected by human activities.