LAUSR

Tire and road wear particles (TRWPs) are an appreciable source of microplastics (MPs); however, knowledge of their large-scale occurrence and mass flux based on robust sampling and quantification is limited. Herein, the first city-wide survey of TRWPs across environmental compartments (road dust, snowbank, water, and sediment from rivers and lakes) along four ring roads (beltways) in Beijing was performed. TRWP concentrations (n = 74) were quantified using bonded-sulfur as a marker to reveal the city-wide spatial distributions and adopted to establish a framework estimating TRWP emission factors (EFs) and mass flux from generation to remote atmospheric, terrestrial, and aquatic transport. The TRWP concentrations were 0.46 × 104-3.55 × 104 μg/g (road dust), 0.65-46.18 mg/L (water), 0.28 × 104-1.79 × 104 μg/g (sediment), and 9.46-19.12 mg/L (snowbank) and were highly related to nearby traffic conditions. Based on total EFs (34.4-288.5 mg/vKT) and airborne EFs (6.2-17.2 mg/vKT) calculated from the preceding concentrations, the TRWP emissions in Beijing were determined as 1.28 × 104 t/a. Among them, 61.3% was eventually disposed of in landfills owing to frequent road sweeping and high runoff treatment efficiency and 18.1% was stranded on the roadside; nevertheless, 11.9% escaped to freshwater systems and 5.7 and 3.0% airborne transported to remote land and ocean, respectively. This study provides new insights into the emissions and fate of TRWPs.