1Center for Global Change Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
2State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing, China
3Norwegian Institute for Air Research, Kjeller, Norway
4Ministry of Education Key Laboratory for Earth System Modeling, Center for Earth System Science, Tsinghua University, Beijing, China
5College of Environment and Energy, South China University of Technology, University Town, Guangzhou, China
6Air Quality Studies, Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong, China
7College of Environmental Engineering and Science, Qilu University of Technology, Jinan, Shandong, China
8Institute of Space and Earth Information Science, The Chinese University of Hong Kong, Hong Kong, China
Received: 19 Aug 2015 – Discussion started: 11 Sep 2015
Abstract. Benzene (C6H6) and toluene (C7H8) are toxic to humans and the environment. They are also important precursors of ground-level ozone and secondary organic aerosols and contribute substantially to severe air pollution in urban areas in China. Discrepancies exist between different bottom-up inventories for benzene and toluene emissions in the Pearl River Delta (PRD) and Hong Kong (HK), which are emission hot spots in China. This study provides top-down estimates of benzene and toluene emissions in the PRD and HK using atmospheric measurement data from a rural site in the area, Heshan, an atmospheric transport model, and an inverse modeling method. The model simulations captured the measured mixing ratios during most pollution episodes. For the PRD and HK, the benzene emissions estimated in this study for 2010 were 44 (12–75) and 5 (2–7) Gg yr−1 for the PRD and HK, respectively, and the toluene emissions were 131 (44–218) and 6 (2–9) Gg yr−1, respectively. Temporal and spatial differences between the inversion estimate and four different bottom-up emission estimates are discussed, and it is proposed that more observations at different sites are urgently needed to better constrain benzene and toluene (and other air pollutant) emissions in the PRD and HK in the future.
Revised: 09 Feb 2016 – Accepted: 16 Feb 2016 – Published: 15 Mar 2016
Fang, X., Shao, M., Stohl, A., Zhang, Q., Zheng, J., Guo, H., Wang, C., Wang, M., Ou, J., Thompson, R. L., and Prinn, R. G.: Top-down estimates of benzene and toluene emissions in the Pearl River Delta and Hong Kong, China, Atmos. Chem. Phys., 16, 3369-3382, doi:10.5194/acp-16-3369-2016, 2016.