Evolution process and sources of ambient volatile organic compounds during a severe haze event in Beijing, China.
108 ambient volatile organic compounds (VOCs) were measured continuously at a time resolution of an hour using an online gas chromatography-frame ionization detector/mass spectrometry (GC-FID/MS) in October 2014 in Beijing, and positive matrix factorization (PMF) was performed with online data. The evolution process and causes for high levels of VOCs during a haze event were investigated through comprehensive analysis. Results show that mixing ratios of VOCs during the haze event (89.29 ppbv) were 2 to 5 times as that in non-haze days, There was a distinct accumulation process of VOCs at the beginning of the haze event, and the mixing ratios of VOCs maintained at the high levels until to the end of pollution when the mixing ratios of ambient VOCs recovered to the normal concentration levels in a few hours. Some reactive and toxic species increased remarkably as well, which indicates a potential health risk to the public in terms of VOCs. Eight sources were resolved by PMF, and results revealed gasoline exhaust was the largest contributor (32-46%) to the ambient VOCs in Beijing. Emissions of gasoline exhaust surged from 13.46 to 40.36 ppbv, with a similar variation pattern to total VOCs, indicating that high levels of VOCs were largely driven to by expanded vehicular emissions. Emissions of biomass burning also increased noticeably (from 2.32 to 11.12 ppbv), and backward trajectories analysis indicated regional transport of biomass burning emissions. Our findings suggested that extremely high levels of VOCs during the haze event was primarily attributed to vehicular emissions, biomass burning and regional transport, as well as stationary synoptic conditions.
College of Environmental Sciences and Engineering, State Key Joint Laboratory of Environmental Simulation and Pollution Control, Peking University, Beijing 100871, China.
Rongrong
R
Wu
College of Environmental Sciences and Engineering, State Key Joint Laboratory of Environmental Simulation and Pollution Control, Peking University, Beijing 100871, China.
Jing
J
Li
College of Environmental Sciences and Engineering, State Key Joint Laboratory of Environmental Simulation and Pollution Control, Peking University, Beijing 100871, China.
Yufang
Y
Hao
College of Environmental Sciences and Engineering, State Key Joint Laboratory of Environmental Simulation and Pollution Control, Peking University, Beijing 100871, China.
Yaqi
Y
Li
College of Environmental Sciences and Engineering, State Key Joint Laboratory of Environmental Simulation and Pollution Control, Peking University, Beijing 100871, China.
Limin
L
Zeng
College of Environmental Sciences and Engineering, State Key Joint Laboratory of Environmental Simulation and Pollution Control, Peking University, Beijing 100871, China. Electronic address: sdxie@pku.edu.cn.
Shaodong
S
Xie
D000393:Air Pollutants / Q000032:analysis*; D000068476:Beijing; D004784:Environmental Monitoring; D010126:Ozone / Q000032:analysis; D012621:Seasons; D001335:Vehicle Emissions / Q000032:analysis; D055549:Volatile Organic Compounds / Q000032:analysis*
D000393:Air Pollutants; D001335:Vehicle Emissions; D055549:Volatile Organic Compounds; D010126:Ozone
Biomass burning; Evolution process; Source apportionment; VOCs; Vehicular emissions