Quantitatively assessing the risks and possible sources of toxic metals in soil from an arid, coal-dependent industrial region in NW China

Comprehensive studies on toxic metal pollution in the soils of arid coal-mining areas have not drawn the attention they deserve. In the present study, we investigated the concentrations of 6 pollutants (Zn, Cu, Cr, Pb, Hg, and As) in soils of an arid mining area, the Eastern Junggar Basin (EJB) of Xinjiang, Northwestern China. Noticeable concentrations were found for Cr, Hg, and As, whereas Zn, Cu, and Pb were lower than their provincial (Xinjiang) guideline values. The average enrichment of As exceeded both Quality Standards (I and II) for soil recommended by the Chinese Environmental Protection Administration, whereas other metals were found within the allowable values of Soil Quality Standard I. There were different degrees of comprehensive ecological risks in the area, and Hg was the major contributor to the PER. In health risk assessments, children seem to have a higher health risk hazards than adults, with As as the primary contributor, followed by Cr. The positive matrix factorization (PMF) model explains five possible sources, including coal combustion, vehicle emissions, atmospheric deposition, industrial discharge, and natural factors, which accounted for 20.79%, 16.83%, 16.83%, 27.72%, and 17.82% of the total contribution, respectively. The results will be informative for local authorities to establish more effective targeting policies to control the spread of contaminants and provide reference materials for soil quality protection and improvement and other research programs in this area.