Interactive migration of heavy metals between dust and soil demonstrated by the coupling coordination analysis

To explore the pollution status of heavy metals in surface dust and soil at bus stops in Weiyang District, Xi'an, 52 surface dust and soil samples were collected. Pollution assessment methods such as the Index of Geo-accumulation (I_geo) and the Nemerow Comprehensive Pollution Index were used to assess the pollution status of six heavy metals, Cr, Mn, Cu, Zn, As, and Pb, in 104 samples. To our knowledge, for the first time, the coupling coordination of heavy metal concentrations between dust and soil was studied. The average concentrations of heavy metals in dust and soil, except for As and Mn, were higher than the background values of soil in Shaanxi Province. Spatially, the concentrations of heavy metals in dust were generally higher in the east and lower in the west, while in the soil, they were higher in the south and lower in the north. The main sources were traffic, natural, and industrial sources. Hand-to-mouth ingestion was the main exposure route for both adults and children. The non-carcinogenic risk for children was higher than that for adults. The coupling coordination degree of heavy metal concentrations between surface dust and soil was at a moderate level, which means that there is a certain interactive migration between dust and soil heavy metals, and the pollution sources could be similar. Overall, our study provides everyone with references for single-medium and multi-medium heavy metal migration models.