Source-Dependent Bioaccessibility of Potentially Toxic Elements in Multi-Size Urban Road Dust: Health Risks and Carbon Emission Reduction Implications

Urban road dust is an important way for people to contact potentially toxic elements (PTEs). However, the correlation between the bioaccessibility of PTEs in road dust and the contribution rate of pollution sources has not yet reached a consensus. Road dust was divided into three particle sizes (<63, 63–125, and 125–250 μm). Then, the Mantel test was used to analyze the correlation between the contributions of the four pollution sources (composite sources, traffic sources, industrial sources, and fuel combustion) and the bioaccessibility of PTEs. Finally, by incorporating bioaccessibility into the health risk assessment system, Ni was identified as the priority lifetime carcinogenic risk element and fossil fuel combustion as the priority pollution source. The remediation target obtained by the probabilistic risk assessment of bioaccessibility guidance is 3.91 times the target value based on the total content and reduces carbon emissions by 22.6%. Overall, this study not only enhances the precision of identifying pollution sources and pollutants in complex urban environments by integrating PMF with the bioaccessibility of PTEs but also highlights the potential value of bioaccessibility in urban environmental management for carbon emission reduction. This facilitates the implementation of precise risk assessments and low-carbon sustainable development.