Implications of changing urban and rural emissions on non-methane hydrocarbons in the Pearl River Delta region of China

Abstract

Guangzhou (GZ) is one of the highly industrialized and economically vibrant cities in China, yet it remains relatively understudied in terms of its air quality, which has become severely degraded. In this study, extensive air sampling campaigns had been conducted at GZ urban sites and in Dinghu Mountain (DM), a rural site, in the Pearl River Delta (PRD) during the spring of 2001 and 2005. Additionally, roadside and tunnel samples were collected in GZ in 2000 and 2005. Later, exhaust samples from liquefied petroleum gas (LPG)-and gasoline-fueled taxis were collected in 2006. All samples were analyzed for C 2 -C 10 non-methane hydrocarbons (NMHCs). NMHC profiles showed significant differences in the exhaust samples between gasoline-and LPG-fueled taxis. Propane (47%) was the dominant hydrocarbon in the exhaust of the LPG-fueled taxis, while ethene (35%) was the dominant one in that of gasoline-fueled taxis. The use of LPG-fueled buses and taxis since 2003 and the leakage from these LPG-fueled vehicles were the major factors for the much higher level of propane in GZ urban area in 2005 compared to 2001. The mixing ratios of toluene, ethylbenzene, m/p-xylene and o-xylene decreased at the GZ and DM sites between 2001 and 2005, especially for toluene in GZ, despite the sharp increase in the number of registered motor vehicles in GZ. This phenomenon was driven in part by the closure of polluting industries as well as the upgrading of the road network in urban GZ and in part by the implementation of more stringent emission standards for polluting industries and motor vehicles in the PRD region. r

Source attributions of hazardous aromatic hydrocarbons in urban, suburban and rural areas in the Pearl River Delta (PRD) region

“…Significant correlations (p < 0.01) were observed between toluene and benzene at all sites. The T/B slopes at WQS, GEMC and HEMC were 2.49 ± 0.12, 1.77 ± 0.08 and 1.56 ± 0.08, respectively, which were between that observed in industry city Dongguan (T/B = 4.82 and 4.87) [3,5] and that of vehicle exhausts (T/B = 1.43 for tunnel and 1.94 for roadside) [23,28], and were also consistent with those previously reported at various locations in the PRD region [5,25,26,28,72]. T/B slopes closer to that of vehicle exhausts at GEMC and HEMC in fact reflected the fact that vehicle exhausts were the sources much more important in the urban commercial/business/dwelling areas like GEMC and its downwind areas like HEMC.…”

“…In the PRD region, the rapid growth in economy has resulted in fast increase in anthropogenic emissions of air pollutants [21], and as an important class of anthropogenic volatile organic compounds (VOCs), AHs were found to have comparatively higher ambient levels [3,5,[22][23][24][25][26] with tremendous impacts on air quality in the region. Studies showed that in the PRD region ozone formation was largely VOC-limited with AHs among the most important precursors [26][27][28][29], and AHs alone were responsible for over 75% secondary organic carbon in fine particles [20].…”

Sources of C2–C4 alkenes, the most important ozone nonmethane hydrocarbon precursors in the Pearl River Delta region

“…Gasoline evaporation would contribute substantially to ambient i-pentane (Zhang et al, 2013b). Benzene, as a carcinogenic compound forbidden to be used in industry, was mainly from automobile exhausts in urban area (Zhao et al, 2004;Barletta et al, 2008;Tang et al, 2008) and mainly from biomass burning in rural areas (Holzinger et al, 2001). Toluene was widely used as solvents in painting, coating, printing and cleaning processes in the highly industrialized PRD region (Chan et al, 2006; Y.L.…”

Emerging Air Pollution Issues in Changing Pearl River Delta of South China

“…Such massive changes of industry structure and prevalent fuel are anticipated to have strong effects on air quality. For instance, Tang et al (2008) reported that there have been around 1.5 times increases in propane concentration in Guangzhou due to the introduction of LPG to the city in 2003. This pilot study highlights the scientific importance of clear understanding of the emerging air pollution issues along with these economic and industrial changes.…”