Emissions And Light Absorption Of Carbonaceous Aerosols From On-Road Vehicles In An Urban Tunnel In South China

With changing numbers, compositions, emission standards and fuel quality of on-road vehicles, it is imperative to accordingly characterize and update vehicular emissions of carbonaceous aerosols for better understanding their health and climatic effects. In this study, a 7-day field campaign was conducted in 2019 in a busy urban tunnel (>30,000 vehicles day(-1)) in south China with filter-based aerosol samples collected every 2 hat both the inlet and the outlet for measuring carbonaceous aerosols and their light absorbing properties. Observed fleet average emission factor (EF) of total carbon (TC) was 13.4 +/- 8.3 mg veh(-1) km(-1), and 17.4 +/- 11.3 mg veh(-1) km(-1) if elec-tric and LPG-driven vehicles were excluded; and fleet average EF of organic carbon (OC) and elemental carbon (EC) was 8.5 +/- 6.6 and 4.9 +/- 2.6 mg veh(-1) km(-1) (11.0 +/- 8.8 and 6.3 +/- 3.6 mg veh(-1) km(-1) if excluding electric and LPG vehicles), respectively. Regression analysis revealed an average TC-EF of 319.8 mg veh(-1) km(-1) for diesel vehicles and 2.1 mg veh(-1) km(-1) for gasoline vehicles, and although diesel vehicles only shared similar to 4% in the fleet compositions, they still dominate on-road vehicular carbonaceous aerosol emissions due to their over 150 times higher average TC-EF than gasoline vehicles. Filter-based light absorption measurement demonstrated that on average brown carbon (BrC) could account for 19.1% of the total carbonaceous light absorption at 405 nm, and the average mass absorption efficiency of EC at 635 nm and that of OC at 405 nm were 5.2 m(2) g(-1) C and 1.0 m(2) g(-1) C, respectively. (C) 2021 Elsevier B.V. All rights reserved.