[Analysis of Heavy Metal Sources in Soil in Ping'an Basin Based on APCS-MLR and PMF Models]

In order to find out the background characteristics of heavy metals in the soil of Ping'an Basin and identify the types of donors, based on the detection values of Cd, Hg, As, Pb, Cr, Cu, Zn, and pH of 3 006 groups of soils in the area, the enrichment status and potential ecological risks were analyzed by the combination evaluation method, and the APCS-MLR and PMF models were used to determine the types of soil heavy metal sources. The results showed that: ① The soil Hg and Pb contents were lower than background contents of China, and Cu, Zn, Cr, Cd, and As contents were higher than background contents of China. There was a certain exogenous import of Hg in the human activity area along the Huangshui River. A total of 6% of the As points exceeded the risk control value, and most of them were in the southern mountainous areas, which had little impact on cultivated land. ② From the perspective of potential ecological risks, the E values of Pb and Zn were less than 40, and there was no ecological risk. Cr and Cu had a small number of moderate ecological risk points, and the ecological risk was low. Hg, Cd, and As had medium and high ecological risk points, and there was a certain risk, with Hg>Cd>As characteristics. The RI value of ecological risk in the study area was 102, indicating low risk overall. ③ The APCS-MLR and PMF models complemented and verified each other and jointly resolved the four main heavy metal sources in the study area. That is, sulfide-dominated natural sources, mantle material-dominated natural sources, epigenetically modified natural sources, and human activity interference sources. This study provides technical support for the selection of heavy metal risk prevention and ecological treatment projects in the study area and has guiding significance for the study of heavy metal evolution and ecological effects in typical areas of the Qinghai-Xizang Plateau.