Nonnegligible migration of rubber-derived chemicals from road surface to adjacent greenbelt soil

Rubber-derived chemicals (RDCs) on road surfaces, such as 6PPD-quinone, have garnered significant attention due to their negative effects. However, their distribution and migration from road surfaces to adjacent greenbelt soils remain poorly understood. In this study, 32 representative RDCs were systematically investigated in road dust and roadside greenbelt soils from various functional areas in southern China. The concentrations of RDCs were in the range of 33.3-7750, 4.69-293, and 1.88-78.7 ng/g in road dust, dry-season soils, and wet-season soils, respectively. The predominant compounds were 1,3-Diphenylguanidine (DPG), caprolactam, and 2-Hydroxybenzothiazole (2-OH-BTH). Spatially, the highest concentrations occurred in residential areas and urban villages, followed by commercial areas, while the lowest levels were recorded in parks, reflecting the strong influence of traffic intensity and human activities. Seasonally, the concentrations of RDCs were generally higher in the dry season than in the wet season, likely due to dilution by rainfall. The markedly lower concentrations in soils compared with road dust suggest that rainfall runoff and physical barriers may contribute to limiting the migration of RDCs from roads into adjacent soils. However, the continuous low detection levels indicate a nonnegligible migration of RDCs from road surfaces to adjacent greenbelt soils. Health risk assessment indicated negligible non-carcinogenic risks for both adults and children via soil exposure. This study elucidates the spatiotemporal distribution and migration of RDCs in urban environments, providing essential data for evaluating their environmental fate and health risks.