新疆乌伦古湖表层沉积物重金属形态及污染水平

Study on Forms and Pollution Levels of Heavy Metals in Surface Sediments of Ulungu Lake

乌伦古湖沉积物中重金属元素的释放可能影响湖水质量及生态健康。自然环境及人为活动因素干扰导致了湖泊面积不断萎缩,通过采集乌伦古湖共8个点位的表层沉积物,检测了汞、砷、铅、镉、铜、锌、铬等7种重金属的含量,并用BCR连续提取法分析重金属形态,用内梅罗综合污染指数分析其污染程度。结果表明,乌伦古湖沉积物中重金属含量均可达到海洋沉积物质量标准的指标,其中汞、砷、铅、镉、铬、铜、锌的浓度分别达到0.046 mg/kg、5.55 mg/kg、14 mg/kg、43 mg/kg、0.18 mg/kg、32 mg/kg和57 mg/kg,按平均含量大小排序为:Zn>Cr>Cu>Pb>As>Cd>Hg,分别为我国海洋沉积物质量标准指标(第一类)的0.2、0.3、0.2、0.5、0.4、0.9、0.4倍。乌伦古湖沉积物重金属的形态除了Cd以可还原态和弱酸提取态为主,Cu、Ni、Zn、Pb、Cr的形态主要为残渣态。研究结果可为乌伦古湖生态环境保护提供数据支持。

The release of heavy metals in the sediments of Ulungu Lake may affect the water quality and ecological health of the lake.The natural environmental factors and human activities caused the continuous shrinkage of the lake area.The contents of seven heavy metals,including Hg,As,Pb,Cd,Cr,Cu and Zn,were detected by collecting surface sediments from eight sites in Ulungu Lake,and the heavy metal speciation was analyzed by BCR continuous extraction method,and the pollution degree was analyzed with Nemero comprehensive pollution index.The results showed that the contents of heavy metals in the sediments of Ulungu Lake can meet the indicators of marine sediment quality standards,in which the concentrations of Hg,As,Pb,Cd,Cr,Cu and Zn reach 0.046 mg/kg,5.55 mg/kg,14 mg/kg,43 mg/kg,0.18 mg/kg,32 mg/kg and 57 mg/kg respectively.The decreasing order of average content is:Zn > CR > Cu > Pb > as > CD > Hg,which are 0.2,0.3,0.2,0.5,0.4,0.9 and 0.4 times of China′s marine sediment quality standard index(class I).The forms of heavy metals in the sediments of Ulungu Lake are mainly in reducible and weak acid forms except Cd,while the forms of Cu,Ni,Zn,Pb and Cr are mainly in residue forms.The research results can provide data support for ecological and environmental protection of Ulungu Lake.