Volume 12, No. 3, June 2012, Pages 387-398 PDF(311 KB)
Non-methane Hydrocarbons and Their Ozone Formation Potentials in Foshan, China
Ji-Hua Tan1,3, Song-Jun Guo2, Yong-Liang Ma3, Fu-Mo Yang1, Ke-Bin He3, Yong-Chang Yu4, Jie-Wen Wang4, Zong-Bo Shi5, Gang-Cai Chen6
1 Key Laboratory of Computational Geodynamics, College of Earth Science, Graduate University of Chinese Academy of Sciences, Beijing 100049, China
2 School of Environment Studies, Guangxi University, Nanning 530004, China
3 State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
4 Foshan Environmental Protection Bureau, Foshan 528000, China
5 School of Geography, Earth and Environmental Science, University of Birmingham, Edgbaston Birmingham B15 2TT, United Kingdom
6 Chongqing Environmental Protection Bureau, Chongqing 401147, China
Concentrations of non-methane hydrocarbons (NMHCs) were measured to investigate their temporal variations and major sources, and to explore the ozone formation potentials (OFP) of each NMHCs for the first time in December 2008 in Foshan. Ethane, propane, n-butane, i-pentane, 2,3-dimethylbutane, ethene, propene, ethyne, benzene and toluene were the 10 most abundant hydrocarbons, accounting for 82% of the concentration of total NMHCs. Concentrations of these hydrocarbons as well as their fractional contributions to the total NMHCs were higher in the morning and evening than in the afternoon, consistent with the variations in vehicle volumes during these periods. This suggests that the vehicular emission was likely the major source of NMHCs at this site. The mean B/T ratio (0.45 ± 0.24) further supported vehicular emission as the main source of the ambient NMHCs except for aromatic hydrocarbons. These aromatic hydrocarbons were mainly from solvent evaporation, as indicated by the diurnal variations in the ratios of toluene and m/p-xylene to benzene. The results from factor analysis also showed that combustion process and solvent usage were the major sources of NMHCs. On average, total Prop-Equiv and OFP were 153.0 ppbc and 863.4 μg/m3, respectively. Based on MIR (maximum incremental reactivity) scale, the leading contributors to OFP in decreasing concentrations were ethene, toluene, propene, i-pentane, m/p-xylene, 1-butene, ethylbenzene, o-xylene, 2,3-dimethylbutane and trans-2-butene, which in total explained 77% of the total OFP. Ranking by Prop-Equiv, the top 10 species were propene, toluene, ethene, 1-butene, i-pentane, m/p-xylene, isoprene, 2,3-dimethylbutane, trans-2-butene and ethylbenzene, accounting for 66% of the total Prop-Equiv. Thus, alkenes played the most important role in O3 formation, followed by aromatics and alkanes during the study periods in Foshan.
Non-methane hydrocarbons; vehicular emission; solvent evaporation; ozone formation potential; Foshan.