title: Are emissions of black carbon from gasoline vehicles overestimated? Real-time, in situ measurement of black carbon emission factors.
abstract: Accurately quantifying black carbon (BC) emission factors (EFs) is a prerequisite for estimation of BC emission inventory. BC EFs determined by measuring BC at the roadside or chasing a vehicle on-road may introduce large uncertainty for low emission vehicles. In this study, BC concentrations were measured inside the tailpipe of gasoline vehicles with different engine sizes under different driving modes to determine the respective EFs. BC EFs ranged from 0.005-7.14 mg/kg-fuel under the speeds of 20-70 km/h, 0.05-28.95 mg/kg-fuel under the accelerations of 0.5-1.5m/s(2). Although the water vapor in the sampling stream could result in an average of 12% negative bias, the BC EFs are significantly lower than the published results obtained with roadside or chasing vehicle measurement. It is suggested to conduct measurement at the tailpipe of gasoline vehicles instead of in the atmosphere behind the vehicles to reduce the uncertainty from fluctuation in ambient BC concentration.
authors.affiliation: Key Laboratory for Urban Habitat Environmental Science and Technology, Peking University Shenzhen Graduate School, Shenzhen 518055, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Mechanical and Manufacturing Engineering, University of Calgary, Calgary T2N 1N4, Canada.
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Xing
authors.affiliation: Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
authors.forename: Shuhui
authors.initials: S
authors.lastname: Zhao
authors.affiliation: College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
authors.forename: Mei
authors.initials: M
authors.lastname: Zheng
authors.affiliation: Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Mu
authors.affiliation: Department of Mechanical and Manufacturing Engineering, University of Calgary, Calgary T2N 1N4, Canada. Electronic address: kddu@ucalgary.ca.
authors.forename: Ke
authors.initials: K
authors.lastname: Du
mesh_terms: D000393:Air Pollutants / Q000032:analysis; D000397:Air Pollution / Q000706:statistics & numerical data*; D001272:Atmosphere; D004784:Environmental Monitoring / Q000379:methods*; D005742:Gasoline; D052638:Particulate Matter; D053260:Soot / Q000032:analysis*; D001335:Vehicle Emissions / Q000032:analysis*
chemical_list: D000393:Air Pollutants; D005742:Gasoline; D052638:Particulate Matter; D053260:Soot; D001335:Vehicle Emissions
keywords: Black carbon; Carbon mass balance; Emission factor; Light-duty gasoline vehicle