甘肃某冶炼厂区土壤重金属铅、镉污染特征及其对微生物群落结构的影响

长期受到重金属铅(Pb)和镉(Cd)污染的土壤生态危害指数较高,土壤微生物群落结构容易受到重金属的影响,重金属对土壤微生物的毒性与重金属的生物利用度直接相关。以白银市重金属污染土壤为样本,分析了土壤的理化性质、重金属Pb和Cd的污染状况及土壤微生物群落结构,探究它们之间的关联性。样本采自距离污染中心由近及远的4个位置(分别命名为S1、S2、S3和S4)。采用Hakanson指数法来评估该地重金属生态风险;选用改进的BCR顺序提取法分析Pb与Cd的组分分布情况;利用SPSS和Canoco 4.5对土壤性质、重金属和细菌群落进行相关性分析和冗余分析,探究微生物群落结构与土壤性质和重金属污染之间的相关性。结果表明:白银市该处重金属污染场地3 km以内的土壤均受到严重的Pb、Cd污染。Pb主要以弱酸可提取态和可还原态的形式存在于土壤中,Cd则以弱酸可提取态为主;土壤重金属的危害生态指数均已经达到极高污染风险程度,且危害程度S1>S3>S2>S4;微生物丰度和多样性可能受到土壤性质及重金属的共同影响,与Pb、Cd的污染程度大致呈负相关(S2

Characteristics of Soil Contamination with Heavy Metals(Pb and Cd)in A Smelting Plant of Gansu and Their Effects on Microbial Community Structure

The ecological risk index of lead(Pb)and cadmium(Cd)is high in long-term polluted soil.Soil microbial diversity is easily affected by heavy metals.The toxicity of heavy metals to soil microorganisms is directly related to the bioavailability of heavy metals.In this paper,the contaminated soil in Baiyin City was collected to explore the physical and chemical properties of the soil,the pollution status of Pb and Cd,the microbial community structures,so as to explore the correlation between them.Samples were collected from four sites near and far from the pollution centers(named S1,S2,S3 and S4).Hakanson index was used to evaluate the ecological risk of heavy metals in these samples.The improved BCR sequential extraction was used to analyze the component distribution of Pb and Cd.To explore the internal relationship between soil properties,heavy metal pollution and bacterial communities,bivariate correlation and redundancy analysis between them were conducted by SPSS and Canoco4.5 software.Results showed that the contaminated sites within 3 km were seriously polluted by Pb and Cd.Pb mainly presented in the form of acid-extractable and reducible states,while Cd was in the form of acid-extractable state.The ecological risk index of all the sampling sites had approached a high degree of pollution risk with the harmful level in an order of S1>S3>S2>S4.Microbial abundance and diversities might be affected by not only soil properties but also heavy metals,which was negatively correlated with the concentrations of Pb and Cd(S2