Seasonal Pollution Characteristics and Analysis of the Sources of Atmospheric VOCs in Chengdu Urban Area
【Abstract】To investigate the seasonal variations in the concentrations of atmospheric volatile organic compounds (VOCs) in the urban area of Chengdu, VOC species were monitored from December 2018 to November 2019, and the concentrations, chemical composition, chemical reactivity, and sources of VOCs were analyzed. Average volume fractions of VOCs in spring, summer, autumn, and winter are 32.29 × 10−9, 36.25 × 10−9, 40.92 × 10−9, and 49.48 × 10−9, respectively. The concentrations in winter are significantly higher than the winter concentrations measured in other areas. There is no significant difference between VOC concentrations in spring and summer, but component concentrations vary from season to season. In winter, alkanes account for the largest proportion of total VOCs owing to vehicle emissions. The proportion of oxygen (nitrogen)-containing VOCs in summer and autumn is much higher than that in spring and winter. Volatile emissions from primary sources and secondary conversions have a great contribution. The average concentration of key components of VOCs in different seasons did not change significantly. C2–C4 alkanes, ethylene, acetylene, and dichloromethane concentrations may be significantly affected by vehicle exhaust, oil and gas volatilization, solvent use, and LPG fuel use. ·OH consumption rate and OFP calculations show that key active species are mainly m-/p-xylene, ethylene, propylene, 1-hexene, toluene, isopentane, and n-butane. Therefore, these species should be given priority in emissions control measures. Since the temperature in spring and summer is higher than in autumn and winter, and the UV rays are more intense, PMF analysis reveals the natural sources and the secondary emission sources as the major sources. The oil and gas volatilization sources contribute 9% to VOC concentrations in summer. The major VOC sources in autumn and winter are vehicle exhaust and combustion sources. Emissions from the combustion sources contribute 25% and emissions from the catering sources in autumn and winter contribute 9% to total VOC levels.
【Keywords】 volatile organic compounds (VOCs); seasonal characteristics; chemical reactivity; source apportionment; Chengdu;
(Translated by LIN J)
 Tang X Y, Zhang Y H, Shao M. Atmospheric environmental chemistry (2nd ed.) [M]. Beijing: Higher Education Press, 2006. 214–263 (in Chinese).
 Gee I L, Sollars C J. Ambient air levels of volatile organic compounds in Latin American and Asian cities [J]. Chemosphere, 1998, 36 (11): 2497–2506.
 Yurdakul S, Civan M, Tuncel G.Volatile organic compounds in suburban Ankara atmosphere, turkey: sources and variability [J]. Atmospheric Research, 2013, 120–121: 298–311.
 Zhang J K, Sun Y, Wu F K, et al. The characteristics, seasonal variation and source apportionment of VOCs at Gongga Mountain, China [J]. Atmospheric Environment, 2014, 88: 297–305.
 Pinto D M, Blande J D, Souza S R, et al. Plant volatile organic compounds (VOCs) in ozone (O3) polluted atmospheres: the ecological effects [J]. Journal of Chemical Ecology, 2010, 36 (1): 22–34.
 Tsui J K Y, Guenther A, Yip W K, et al. A biogenic volatile organic compound emission inventory for Hong Kong [J]. Atmospheric Environment, 2009, 43 (40): 6442–6448.
 Duan J C, Tan J H, Yang L, et al. Concentration, sources and ozone formation potential of volatile organic compounds (VOCs) during ozone episode in Beijing [J]. Atmospheric Research, 2008, 88 (1): 25–35.
 Vega E, Mugica V, Carmona R, et al. Hydrocarbon source apportionment in Mexico City using the chemical mass balance receptor model [J]. Atmospheric Environment, 2000, 34 (24): 4121–4129.
 Qin Y, Walk T, Gary R, et al. C2–C10 nonmethane hydrocarbons measured in Dallas, USA-Seasonal trends and diurnal characteristics [J]. Atmospheric Environment, 2007, 41 (28): 6018–6032.
 Saito S, Nagao I, Kanzawa H. Characteristics of ambient C2–C11 non-methane hydrocarbons in metropolitan Nagoya, Japan [J]. Atmospheric Environment, 2009, 43 (29): 4384–4395.
 Wang B G, Zhang Y H, Shao M.Special and temporal distribution character of VOCs in the ambient air of Peal River Delta Region [J]. Environmental Science, 2004, 25 (S1): 7–15 (in Chinese).
 Liu Y, Shao M, Fu L L, et al. Source profiles of volatile organic compounds (VOCs) measured in China: part I [J].Atmospheric Environment, 2008, 42 (25): 6247–6260.
 Xu X, Wang Y S, Liu G R, et al.Measurement and study on the atmospheric trace BTEX in Beijing [J]. Environmental Science, 2004, 25 (3): 14–18 (in Chinese).
 Jiang J. Study on variation of trace volatile Organic compounds in the atmosphere of Beijing [D]. Beijing: Institute of Atmospheric Physics, Chinese Academy of Sciences, 2006 (in Chinese).
 Sun J, Wang Y S, Wu F K, et al. Concentration and change of VOCs in summer and autumn in Tangshan [J]. Environmental Science, 2010, 31 (7): 1438–1443 (in Chinese).
 Wu F K, Wang Y S, An J L, et al. Study on concentration, ozone production potential and sources of VOCs in the atmosphere of Beijing during Olympics period [J]. Environmental Science, 2010, 31 (1): 10–16 (in Chinese).
 Zhang B T, An X X, Wang Q, et al. Temporal variation, spatial distribution, and reactivity characteristics of air VOCs in Beijing 2015 [J]. Environmental Science, 2018, 39 (10): 4400–4407 (in Chinese).
 Cui H X, Wu Y M, Gao S, et al. Characteristics of ambient VOCs and their role in O3 formation: a typical air pollution episode in Shanghai urban area [J]. Environmental Science, 2011, 32 (12): 3537–3542 (in Chinese).
 Cai C J, Geng F H, Yu Q, et al. Source apportionment of VOCs at city centre of Shanghai in summer [J]. Acta Scientiae Circumstantiae, 2010, 30 (5): 926–934 (in Chinese).
 Zhang L L, Jiang W B, Zhang Y X, et al. The characteristics of ambient volatile organic compounds (VOCs) in Qingpu Shanghai, China [J]. China Environmental Science, 2015, 35 (12): 3550–3561 (in Chinese).
 Atkinson R, Arey J. Atmospheric degradation of volatile organic compounds [J]. Chemical Reviews, 2003, 103 (12): 4605–4638.
 Brown S G, Frankel A, Hafner H R.Source apportionment of VOCs in the Los Angeles area using positive matrix factorization [J]. Atmospheric Environment, 2007, 41 (2): 227–237.
 Su L Y. A preliminary study of ambient VOCs variation and chemical reactivity in the urban area of Shanghai, China [D]. Shanghai: East China University of Science and Technology, 2012. 21–23 (in Chinese).
 Na K, Kim Y P.Seasonal characteristics of ambient volatile organic compounds in Seoul, Korea [J]. Atmospheric Environment, 2001, 35 (15): 2603–2614.
 Zou Y, Deng X J, Wang B G, et al. Pollution characteristics of volatile organic compounds in Panyu composition station [J]. China Environmental Science, 2013, 33 (5): 808–813 (in Chinese).
 Guo H, Lee S C, Louie P K K, et al. Characterization of hydrocarbons, halocarbons and carbonyls in the atmosphere of Hong Kong [J]. Chemosphere, 2004, 57 (10): 1363–1372.
 Kim E, Hopke P K, Edgerton E S. Source identification of Atlanta aerosol by positive matrix factorization [J]. Journal of the Air & Waste Management Association, 2003, 53 (6): 731–739.
 Qi Y H. Emission characteristics and environmental impact analysis of volatile organic compounds (VOCs) in petrochemical industry [D]. Ji'nan: Shandong University, 2018. 46–50 (in Chinese).
 Ye W H, Sun X H, Liu J S, et al. Study on air pollution of VOC in arterial traffic [J]. Environmental Monitoring in China, 2009, 25 (6): 85–89 (in Chinese).
 Ying F, Bao Z, Yang C J, et al. Analysis of volatile organic compounds (VOCs) and their atmospheric chemical reactivity in ambient air around urban traffic roads in Hangzhou [J]. Acta Scientiae Circumstantiae, 2012, 32 (12): 3056–3064 (in Chinese).
 Barletta B, Meinardi S, Rowland F S, et al. Volatile organic compounds in 43 Chinese cities [J]. Atmospheric Environment, 2005, 39 (32): 5979–5990.
 Atkinson R, Baulch D L, Cox R A, et al. Evaluated kinetic and photochemical data for atmospheric chemistry: volume Ⅱ-gas phase reactions of organic species [J]. Atmospheric Chemistry and Physics, 2006, 6 (11): 3625–4055.
 Cui T, Cheng J C, He W Q, et al. Emission characteristics of VOCs from typical restaurants in Beijing [J]. Environmental Science, 2015, 36 (5): 1523–1529 (in Chinese).
 Watson J G, Chow J C, Fujita E M.Review of volatile organic compound source apportionment by chemical mass balance [J]. Atmospheric Environment, 2001, 35 (9): 1567–1584.
 Batterman S A, Peng C Y, James B, et al. Levels and composition of volatile organic compounds on commuting routes in Detroit, Michigan [J]. Atmospheric Environment, 2002, 36 (39–40): 6015–6030.