Characteristic of PM_2.5 potentially toxic elements from the Plateau City (Kunming), Southwest China

Potentially toxic elements (PTEs) pollution in the air and its sources and risks have become a major environmental problem faced by developing countries, especially plateau cities. This study determined the concentrations of seven PTEs in PM_2.5 by Inductively Coupled Plasma Mass Spectrometry (ICP-MS), and comprehensively utilized methods such as geoaccumulation index (I_geo), enrichment factor (EF), principal component analysis (PCA), potential ecological risk index and health risk assessment to systematically analyze their pollution levels, sources and environmental risks. The results indicated that Cd pollution was the most severe (I_geo = 6.80 ± 0.49), while Tl pollution was the least (I_geo = 1.60 ± 0.53). The EF values of Cd and Ni are greater than 10, and the EF value of Cd even exceeds 100, indicating strong anthropogenic interference. PCA analysis indicates that traffic emissions, agricultural activities, industrial production, corrosion of building materials and combustion of fossil fuels are the main sources. The potential ecological risk assessment indicates that Cd has an extremely high single-element ecological risk (E_i = 5320.80 ± 1886.59). All non-carcinogenic health risks fall within the acceptable safety range (HQ < 1). However, the carcinogenic risk assessment reveals that Cr (Ⅵ) and As pose significant carcinogenic risks, and Ni exposure in adults should not be overlooked. This study provides multi-angle scientific evidence for PTE pollution in PM_2.5 in plateau cities, emphasizing the need to take targeted intervention measures to reduce the risk of PTE exposure.