Seasonal Dynamics and Source Apportionment of Heavy Metals in Road Dust: A Case Study of Liuzhou, China

The spatial distribution and seasonal variation in heavy metal pollution in road dust in Liuzhou, China, were investigated. Road dust samples were collected during both drought and wet periods, and the concentrations of nine heavy metals—Cr, Ni, Cu, Pb, Zn, Cd, As, Sb, and Hg—were analyzed. The analysis showed that all nine heavy metals were higher than the background values of Chinese urban soils in both the drought and wet periods, and the mean heavy metal contents of road dust in the dry period were higher than those in the wet period, except for Cd. In the assessment of the pollution of heavy metals in road dust, the results of Igeo showed that Cd and Hg were significant; the results of NI showed that Cr and Ni were more significant. The spatial analysis shows that the industrial concentration areas in the north and west of Liuzhou City are concentration areas of heavy metal pollution. A Pearson correlation analysis showed high correlation between Cd in road dust heavy metals and Cd in the surrounding soil. Source identification via PCA revealed four main contributors: metallurgical and coal-fired industries, mechanical manufacturing, green belt maintenance, and waste treatment facilities. A quantitative analysis via APCS-MLR modeling confirmed that metallurgical and coal-fired industrial sources are the most widespread and important pollution sources in Liuzhou. There is a significant increase in the contribution of waste treatment sources to Hg contamination during wet periods.