VOC species and emission inventory from vehicles and their SOA formation potentials estimation in Shanghai, China

摘要

Volatile organic compound (VOC) species from vehicle exhausts and gas evaporation were investigated by chassis dynamometer andon-road measurements of nine gasoline vehicles, seven diesel vehicles, fivemotorcycles, and four gas evaporation samples. The secondary organic aerosol(SOA) mass yields of gasoline, diesel, motorcycle exhausts, and gasevaporation were estimated based on the mixing ratio of measured C2–C12 VOCspecies and inferred carbon number distributions. High aromatic contentswere measured in gasoline exhausts and contributed comparatively more SOA yield. A vehicular emission inventory was compiled based on a localsurvey of on-road traffic in Shanghai and real-world measurements of vehicleemission factors from previous studies in the cities of China. Theinventory-based vehicular organic aerosol (OA) productions to total COemissions were compared with the observed OA to CO concentrations (ΔOA / ΔCO) in the urban atmosphere. The results indicate that vehiclesdominate the primary organic aerosol (POA) emissions and OA production,which contributed about 40 and 60 % of OA mass in the urban atmosphereof Shanghai. Diesel vehicles, which accounted for less than 20 % ofvehicle kilometers of travel (VKT), contribute more than 90 % of vehicularPOA emissions and 80–90 % of OA mass derived by vehicles in urbanShanghai. Gasoline exhaust could be an important source of SOA formation.Tightening the limit of aromatic content in gasoline fuel will be helpful toreduce its SOA contribution. Intermediate-volatile organic compounds (IVOCs)in vehicle exhausts greatly contribute to SOA formation in the urbanatmosphere of China. However, more experiments need to be conducted todetermine the contributions of IVOCs to OA pollution in China.