Identification of the spatial distributions, pollution levels, sources, and health risk of heavy metals in surface dusts from Korla, NW China

A total of 54 surface dust samples were gathered from Korla in NW China, and the concentrations of six heavy metal elements, such as Hg, Cd, As, Pb, Cr, and Cu, were determined by standard methods. The geostatistical analysis, multivariate statistical analysis, pollution load index (PLI), and the US EPA health risk assessment model were used to analyze the spatial distribution, pollution, and its potential health risk of heavy metals in surface dusts, and the main sources of heavy metals were also identified. The obtained results indicate that the average concentrations of As in surface dust of Korla is lower than the background values determined in Xinjiang soil, whereas the average concentrations of Hg, Cd, Pb, Cr, and Cu elements exceeded the corresponding background values by factors of 3.71, 1.87, 1.96, 1.14, and 1.29, respectively. The higher concentration of analyzed heavy metals is observed in the northeastern and northern parts in the study area. The pollution level of heavy metals decreased in the following order: Hg > Pb > Cd > Cu > Cr > As. Based on the identified concentrations, the collected dust samples are found to be heavily polluted by Hg and slightly polluted by As, and the remaining elements, Pb, Cd, Cu, and Cr, are found to be low polluted. Furthermore, the PLI values of heavy metals in surface dust vary between 0.74 and 2.74, with an average value of 1.40, at the low pollution level. In addition, As in surface dust in the study area is mainly natural source, while Hg, Cd, Cr, Cu, and Pb are mainly anthropogenic sources. Overall, the carcinogenic and noncarcinogenic health risks of the analyzed elements, instigated mainly by oral ingestion of surface dust, are found to be within the acceptable range for both children and adults. As and Cr are the main noncarcinogenic elements, whereas Cr is the major carcinogenic element among the investigated dust-bound heavy metals in Korla.