西藏年楚河流域农用地土壤重金属分布与生态风险评价

Distribution of soil heavy metals and ecological risk assessment of agricultural land in Nianchu River basin,Tibet

以西藏年楚河流域江孜县、白朗县农用地土壤为研究对象,对Hg、As、Pb、Cd、Cr、Cu、Mn、Zn和Ni 9种重金属进行调查;采用单因子指数法、内梅罗综合污染指数法等方法,结合空间插值法评价年楚河流域农用地土壤重金属污染状况,同时运用相关性和主成分分析探究土壤重金属来源。结果表明:(1)农用地土壤中Hg、Cu、Mn和Ni浓度与西藏土壤环境背景值相比,均表现为不同程度的累积,与GB 15618—2018《土壤环境质量农用地土壤污染风险管控标准(试行)》比较,As元素超标率最大;从江孜县到白朗县,农用地土壤重金属综合生态风险指数逐步增大;(2)研究区的区域污染负荷指数为1.45,属低污染等级,重度污染集中在白朗县;(3)主成分分析表明,9种重金属的来源可分为自然与人为源复合因子、矿山开采因子、农业因子、土壤母质因子和大气传输因子。

Taking the cultivated soil in Bailang County and Jiangzi County of Nianchu River basin in Tibet as the research objects,the contents of 9 kinds of heavy metals,Hg,As,Pb,Cd,Cr,Cu,Mn,Zn and Ni,were investigated and analyzed.The single factor index method,Nemerow comprehensive pollution index method and other methods,combined with the spatial interpolation method were used to evaluate the heavy metal pollution of agricultural land in Nianchu River basin.Meanwhile,correlation analysis and principal component analysis were used to explore the sources of soil heavy metals.The results showed that:(1)The content of Hg,Cu,Mn and Ni in the soil of agricultural land showed different degrees of accumulation,compared with the background values of the soil environment in Tibet.Compared with Soil Environmental Quality:Risk Control Standard for Soil Contamination of Agricultural Land(GB 15618-2018),As had the highest rate exceeding the standard.From Jiangzi County to Bailang County,the comprehensive ecological risk index of soil heavy metals in agricultural land gradually increased.(2)The regional pollution load index of the study area was 1.45,which was a low pollution level.Severe pollution was concentrated in Bailang County.(3)Principal component analysis showed that the sources of 9 kinds of heavy metals could be divided into natural and anthropogenic complex factors,mining factors,agricultural factors,soil parent material factors and atmospheric transmission factors.