银川市浅层表土重金属污染特征及源解析

Characteristics and source identification of heavy metal pollution in shallow topsoil in Yinchuan City

为全面掌握我国西北地区城市表土重金属污染状况,以银川市浅层表土(0~2cm)为研究对象,通过测定常见土壤重金属含量(Cd、Cr、Cu、Ni、Pb和Zn),对表土重金属的污染状况进行评价与污染溯源.首先采用单因子污染指数法、内梅罗综合指数法及潜在生态风险指数法对土壤重金属污染状况及其潜在生态风险进行评价.应用反距离加权插值法分析土壤重金属空间分布特征.通过相关性分析和主成分分析确定重金属污染源.在此基础上,结合西北地区多个重点城市表土重金属污染的相关文献分析,探讨西北地区城市表土重金属污染状况.结果表明,银川市浅层表土中Ni和Cr含量低,Cu、Pb和Zn存在不同程度累积趋势,Cd存在明显富集.Cr、Ni的平均含量低于宁夏土壤背景值,分别为背景值的0.95倍和0.73倍.Cd、Cu、Pb和Zn元素的平均含量均高于宁夏土壤背景值,分别为背景值的1.70倍、1.00倍、1.08倍、1.09倍.单因子污染程度为Cd>Zn>Pb>Cu>Cr>Ni,平均内梅罗综合污染指数评价结果为轻度污染水平.单项生态风险指数结果表明Cd、Cr、Cu、Ni、Pb和Zn具有轻微生态风险,综合潜在生态风险指数结果为轻微生态风险.银川市浅层表土中Cr、Ni多为自然来源,Cd、Cu、Pb、Zn主要为交通和农业污染,此外Cd同时受工业污染影响.中国西北地区城市土壤重金属均存在一定的富集,但累积程度整体不高,交通源、工业源和自然源为主要来源.我国西北地区土壤中Cd污染严重,在工、农、交通发展中值得进一步关注.

To comprehensively assess the status of heavy metal contamination in the topsoil of a city in Northwest China,this study focused on the 0~2cm surface layer in Yinchuan City.The Single Factor Index,Nemerow Pollution Index,and Potential Ecological Risk Index were utilized to gauge heavy metal pollution and potential ecological hazards.The spatial distribution patterns of soil heavy metals were examined using the inverse distance weighted interpolation method.Correlation analysis and principal component analysis were employed to identify pollution sources.Subsequently,the research expanded to include an analysis of topsoil heavy metal contamination in several key cities across Northwest China,with a discussion on the regional implications of the findings.The study revealed that concentrations of Ni and Cr in Yinchuan's shallow topsoil were relatively low,whereas Cu,Pb,and Zn demonstrated varying levels of accumulation,with Cd exhibiting significant enrichment.The average values of Cr and Ni were lower than the background values of Ningxia soil,which were 0.95 and 0.73 times the background values,respectively.The average values of Cd,Cu,Pb,and Zn elements were higher than the background values of Ningxia soil,which were 1.70 times,1.00 times,1.08 times,and 1.09 times,respectively.The pollution levels,according to the Single Factor Index,were ranked as Cd>Zn>Pb>Cu>Cr>Ni,and the average Nemerow Pollution Index indicated a mild pollution level.Ecological risk assessments showed minor risks associated with Cd,Cr,Cu,Ni,Pb,and Zn,and the comprehensive potential ecological risk index suggested an overall slight risk.In Yinchuan,shallow topsoil concentrations of Cr and Ni were predominantly originated from natural sources,while Cd,Cu,Pb,and Zn were mainly attributed to transportation and agricultural activities,with Cd also being impacted by industrial pollution.Heavy metals in urban soils across Northwest China exhibited some degree of enrichment,yet accumulation levels were not excessive,and the primary contributors were transportation,industry,and natural sources.The significant presence of Cd in the soils of Northwest China was concerning and warranted close scrutiny with respect to industrial,agricultural,and transportation developments.