LAUSR

Trace metal contamination in urban road dust has attracted global concern due to its potential risk to the urban environment and human health. Compared to big cities, relative studies in counties and small towns have not been well quantified. This research identified the trace metal contamination characteristics and possible sources in the road dust of a typical mountainous county and a town in the Three Gorges Reservoir region, southwest China, and their associations with major regional socio-economic factors. The trace metal concentrations were determined, and the contamination levels were assessed. Concentrations of Zn, Pb, and Cu were relatively high in both locations, and a significant accumulation of them was confirmed by the geo-accumulation method. Multivariate analysis and geographic information system (GIS) mapping were combined to explore the sources of trace metals in the investigated area. Anthropogenic activities predominantly affected the contamination levels of Zn, Pb, Cu, and Co, and traffic emission, agricultural activities, and fossil fuel combustion were their main sources. The significant accumulation of Zn should attract special concern for its wide use in industrial and agricultural activities. Population and vehicle density were the main factors that controlled the trace metal contamination levels in the roadway dust. Rapid urbanizing promoted trace metal accumulation in counties and towns. Therefore, it is urgent to make appropriate strategies for trace metal pollution mitigation in the process of urbanization.