滇东南峰丛洼地土壤重金属含量、来源及潜在生态风险评价

为全面了解云南东南部峰丛洼地地区土壤重金属的污染特征及生态风险状况,采用网格化方法采集旱地和水田表层土样共199个,测定其Cd、As、Hg、Cr、Pb、Zn、Cu和Ni含量.分别采用地累积指数法和潜在生态危害指数(RI)法评价土壤重金属污染和潜在生态风险程度,应用聚类分析和绝对主成分分数/多元线性回归(APCS/MLR)法对重金属的来源及贡献大小进行分析.结果表明,土壤Cd、Hg、Cr、Ni和Zn出现不同程度的富集,分别达云南背景值的16. 00、7. 29、1. 46、1. 45和2. 39倍;土壤重金属平均RI为1 039. 3,属于重度生态风险水平,Hg和Cd是主要的生态风险因子;多元统计分析表明,重金属主要有4个来源:化石燃料燃烧(源1)、交通运输(源2)、自然背景(源3)和农业生产(源4),Cd、Cr和Ni的来源以源1为主,Pb和Zn的主要来源为源2,Cu主要受源3控制(贡献率77. 86%),源4为Hg的主导来源(70. 37%),源1和源4对As的贡献率分别为46. 71%、49. 46%.

Concentration Characteristics, Source Analysis, and Potential Ecological Risk Assessment of Heavy Metals in a Peak-cluster Depression Area, Southeast of Yunnan Province

The pollution characteristics, sources, and ecological risk of heavy metals in farmland soils were studied in a peak-cluster depression area southeast of Yunnan Province. In total, 199 topsoil samples were collected using the grid method and contents of eight heavy metals (As, Cd, Cr, Cu, Pb, Ni, Zn, and Hg) were determined. The geoaccumulation index and potential ecological risk index (RI) were used to evaluate soil pollution levels and potential ecological risks, respectively. The absolute principal component scores-multivariate linear regression (APCS-MLR) model and cluster analysis were used to identify the pollution sources and apportion the heavy metals in the soils. The results show that the mean content of Cd, Hg, Cr, Ni, and Zn was higher than their respective background values, exceeding them by up to 16.00, 7.29, 1.46, 1.45, and 2.39 times, respectively. No evidence of the occurrence of other metals was found. The average RI was 1039.3, which represents a high potential ecological risk, with Cd and Hg being the most crucial elements. The APCS-MLR model revealed that natural sources (PC1), traffic sources (PC2), fossil fuel combustion sources (PC3), and agricultural sources (PC4) were the four main contributors of soil heavy metals. The primary source of Cd, Cr, and Ni was PC1, while PC2 was the main source of Pb and Zn. PC3 and PC4 were the main sources of Cu and Hg with contribution rates of 77.86% and 70.37%, respectively. The main sources of As were PC1 (46.71%) and PC4 (49.46%).