SHAO Tianjie, ZHANG Wenting, LI Dongze, FU Gejuan, CHEN Zhiqing, MA Ge, WANG Yanhua
To explore the enrichment characteristics and risks of soil heavy metals along highways and in key areas of aeolian sandy regions, the Wubu-Zizhou-Jingbian section of the Qingdao-Yinchuan Expressway was selected as the research object, and the pollution risks of eight heavy metals (Cd, Pb, Cr, Cu, As, Zn, Ni, and Mn) in the dust along the highway, service areas, toll stations, and tunnels were analyzed systematically. Through the detection of heavy metal concentrations, it was found that Pb and Cd in the study area were the most severely exceeded, with mean values being 2.84 times and 2.23 times the background values, respectively. The coefficient of variation for Cd was as high as 96.63%, indicating significant localized enrichment hotspots. Systematic analysis of the spatial distribution characteristics revealed that the heavy metal content in the study area generally increased from west to east and was significantly regulated by land use types and the intensity of human activities. The index of geo-accumulation (Igeo) was used to assess the pollution degree and level of the exceeding elements, showing that the pollution levels of Cd and Pb in all functional areas were higher than those of other elements, and Zn pollution was significantly enhanced inside tunnels. Meanwhile, the potential ecological risk index and human health risk model were introduced. The results indicated a potential trend for the comprehensive ecological risk index in the study area to evolve toward moderate risk, with Cd being the key contributing element to the ecological risk. Furthermore, based on the absolute principal component scores-multiple linear regression (APCS-MLR) receptor model, the source contributions of soil heavy metals were quantitatively identified. The results reflected that industrial-transport mixed sources (39%), coal combustion-transport emission sources (25%), and agricultural sources (15%) were the main pollution sources. This study systematically reveals the differentiated characteristics and potential risks of soil heavy metal pollution in different functional areas of highways in aeolian sandy regions, and suggests implementing zoned management and control while strengthening health protection for occupational groups.