[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%).