Microplastics in Road Sediment of Typical Urban Districts of Beijing: Characteristics and Risk Assessment

Microplastics (MPs) in urban areas threaten ecosystems, causing water and soil contamination, as well as health risks. This study examined MPs in road sediments from five functional areas in Daxing District, Beijing, using characterization and risk assessment methods. The abundance of MPs ranged from 2060 to 8680 items/kg, with business areas showing the highest levels, followed by traffic, residential, leisure, and cultural/educational areas. These variations are likely influenced by human activities, urbanization, and traffic volume. MPs were primarily in fragmented forms, with polypropylene (PP) (43%-87%) and polyethylene (PE) (5%-33%) being the most common polymers. Fragmentation characteristics varied, with cultural/educational areas showing the highest α values despite fewer large MPs. Lower λ values (2.80-5.00) suggest a higher potential for MPs to break down, possibly contributing to stormwater pollution. Multiple risk assessments indicate that the presence of polymers like PP and PE contributes to elevated MP risks in both traffic and residential areas. These areas have been identified as "hotspots" with moderate to high pollution risks. Despite frequent street cleaning in traffic areas, contamination persists. In contrast, leisure areas, with lower human activity, have a reduced risk of MP contamination. These findings can inform effective control measures for MP pollution in urban road sediments.