Contamination characteristics and source apportionment of potentially toxic elements in the topsoil of Huyi District, Xi'an City, China

Considering the potential ecological and human health risks of potentially toxic elements (PTEs) in topsoil, it is crucial to determine their concentrations and identify their sources. To improve our understanding of PTE accumulation in peripheral areas of cities, soil samples from different parts of Huyi District, Xi'an city were collected, and the concentrations of As, Pb, V, Cr, Cu, Mn, Co, and Zn were determined through X-ray fluorescence spectrometry. The single pollution index value was used to evaluate the PTE contamination levels. The single pollution index values of V, Cr, Mn, Co, Cu, Zn, As, and Pb were 1.00, 1.78, 0.99, 0.93, 1.45, 1.98, 0.72, and 2.06, respectively. The concentrations of Cr, Cu, Pb, and Zn were significantly higher than the corresponding background values. Compared with those in the downtown area, the single pollution index values of Cr and Zn in the study area were slightly higher. The results of the correlation analysis, cluster analysis, and factor analysis demonstrated that natural sources, traffic emission sources, and comprehensive sources were the primary sources of soil PTEs in the study area. Source apportionment based on the absolute principal component score-multiple linear regression (APCS-MLR) receptor model was performed, and the contribution rates of the PTE sources were determined. The contribution rates of natural sources to V, Mn, Co, and As in the topsoil in Huyi District were 68.16%, 74.16%, 63.54%, and 77.25%, respectively. The contribution rates of traffic emission sources to Pb, Zn, and Cu were 53.48%, 60.93%, and 33.82%, respectively. Comprehensive sources were the main contributors to Cr accumulation, at a rate of 45.60%. Therefore, the emissions of PTEs such as Cu, Pb, Zn, and Cr from certain human activities, such as vehicular activities, industrial production, and agricultural production, should be reduced.