Li Jun, Gao Zhan-Dong, Tai Xi-Sheng, Jiao Liang, Zang Fei
College of Urban Environment, Lanzhou City University, Lanzhou 730070, China.
Key Laboratory of Resource Environment and Sustainable Development of Oasis, Gansu Province, Northwest Normal University, Lanzhou 730070, China.
Huan Jing Ke Xue. 2024 Aug 8;45(8):4837-4846. doi: 10.13227/j.hjkx.202308137.
To understand the pollution status, distribution characteristics, and pollution sources of soil heavy metals in tourist cities in northwest China, the soil content of heavy metals As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn in the main areas of Dunhuang City was collected and analyzed. The soil heavy metal pollution level was quantitatively evaluated by the methods of the geo-accumulation index and improved Nemerow pollution index, and the sources of heavy metal pollution were quantitatively analyzed using cluster analysis and the positive matrix factorization （PMF） model. The contribution rate of each pollution source to ecological risk was determined by combining the PMF model and comprehensive ecological risk index. The results showed that except for the mean contents of As and Ni, the mean contents of Cd, Cr, Cu, Hg, Pb, and Zn were all higher than the background values in Gansu Province. However, the average content of the eight elements was lower than the screening value of construction land in the Standard for Soil Pollution Risk Control of Soil Environmental Quality Construction Land （trial） （GB 36600-2018）. Among them, the enrichment of Cd, Pb, and Hg was more serious, and the exceedance rate was higher than 90%. The results of the geo-accumulation index indicated that urban soils were mainly polluted by Hg in the study area, and Cd, Cr, Cu, Pb, and Zn pollution also existed in different degrees. The improved Nemerow pollution index illustrated that the comprehensive pollution degree of the soil was clean to moderate pollution, and the overall pollution was light pollution. Based on the PMF model, we could conclude that soil heavy metals in the study area were affected by natural sources, industrial deposition sources, industrial sources, traffic sources, and comprehensive sources, and the contribution rates were 29.28%, 25.86%, 20.13%, 16.5%, and 8.23%, respectively. The specific source-integrated ecological risk assessment model found that the industrial deposition source contributed the most to the ecological risk in the study area and could be regarded as the priority control pollution source, and Hg was considered to be the priority control pollution element for ecological risk.
为了解中国西北旅游城市土壤重金属的污染状况、分布特征及污染来源，采集并分析了敦煌市主要区域土壤中重金属砷（As）、镉（Cd）、铬（Cr）、铜（Cu）、汞（Hg）、镍（Ni）、铅（Pb）和锌（Zn）的含量。采用地累积指数法和改进的内梅罗污染指数法对土壤重金属污染程度进行定量评价，运用聚类分析和正定矩阵因子分解（PMF）模型对重金属污染来源进行定量分析。结合PMF模型和综合生态风险指数确定各污染来源对生态风险的贡献率。结果表明，除As和Ni的平均含量外，Cd、Cr、Cu、Hg、Pb和Zn的平均含量均高于甘肃省背景值。然而，这8种元素的平均含量低于《土壤环境质量建设用地土壤污染风险管控标准（试行）》（GB 36600—2018）中建设用地的筛选值。其中，Cd、Pb和Hg的富集较为严重，超标率均高于90%。地累积指数结果表明，研究区域城市土壤主要受Hg污染，Cd、Cr、Cu、Pb和Zn也存在不同程度污染。改进的内梅罗污染指数表明，土壤综合污染程度为清洁至中度污染，整体污染为轻度污染。基于PMF模型可知，研究区域土壤重金属受自然源、工业沉降源、工业源、交通源和综合源的影响，贡献率分别为29.28%、25.86%、20.13%、16.5%和8.23%。特定源-综合生态风险评估模型发现，工业沉降源对研究区域生态风险的贡献最大，可视为优先控制污染源，Hg被认为是生态风险的优先控制污染元素。
