滇西北剑湖表层沉积物重金属分布特征和生态风险

Distributions and ecological risks of heavy metals in surface sediments from Jianhu Lake,Northwestern Yunnan Plateau,China

采用电感耦合等离子体发射光谱(ICP-OES)仪测定剑湖表层沉积物4种重金属Cd、Cu、Pb、Zn含量,采用改进BCR连续提取法提取4种重金属各形态含量,结合空间插值方法对4种重金属空间分布特征和生态风险进行了分析。结果表明,剑湖表层沉积物呈碱性,以砂砾为主,湖周浅水区总有机碳含量高于湖心区,重金属迁移转化能力弱,主要以残渣态为主,可氧化态含量最低。同时,剑湖表层沉积物中Cd和Cu以人为富集为主,Pb和Zn以自然富集为主,重金属均处于轻微或中等风险程度。湖周浅水区富集程度高于湖心区,而湖心区生态风险高于湖周浅水区。

Inductively coupled plasma-optical emission spectrometry(ICP-OES)was used to determine the concentrations of four heavy metal elements,Cd,Cu,Pb and Zn,in surface sediments from Jianhu Lake.The modified BCR sequential extraction methods were used to extract the different fractions of four heavy metal elements,and then the distributions and ecological risks of these heavy metals were analyzed through the spatial interpolation method.Results showed that in surface sediments of Jianhu Lake,pH was alkaline,and the soil particles were mainly gravel.The total organic carbon concentration in shallow water area was higher than that in the central area.The ability of migration and transformation of these heavy metals was weak.The content of the residual fraction of heavy metals was the highest,while the oxidizable fraction was the lowest.Meanwhile,in surface sediments of Jianhu Lake,Cd and Cu were mainly enriched by humans process,Pb and Zn were enriched by natural process,and all these heavy metals had slight or moderate risks.The extent of heavy metal enrichments in shallow water area was higher than that in central area,while the ecological risks in central area was higher than that in shallow water area.