C1–C8 volatile organic compounds in the atmosphere of Hong Kong: Overview of atmospheric processing and source apportionment

Abstract

We present measurements of C 1-C 8 volatile organic compounds (VOCs) at four sites ranging from urban to rural areas in Hong Kong from September 2002 to August 2003. A total of 248 ambient VOC samples were collected. As expected, the urban and suburban sites generally gave relatively high VOC levels. In contrast, the average VOC levels were the lowest in the rural area. In general, higher mixing ratios were observed during winter/spring and lower levels during summer/fall because of seasonal variations of meteorological conditions. A variation of the air mass composition from urban to rural sites was observed. High ratios of ethyne/CO (5.6 pptv/ppbv) and propane/ethane (0.50 pptv/pptv) at the rural site suggested that the air masses over the territory were relatively fresh as compared to other remote regions. The principal component analysis (PCA) with absolute principal component scores (APCS) technique was applied to the VOC data in order to identify and quantify pollution sources at different sites. These results indicated that vehicular emissions made a significant contribution to ambient non-methane VOCs (NMVOCs) levels in urban areas (65736%) and in suburban areas (50728% and 53741%). Other sources such as petrol evaporation, industrial emissions and solvent usage also played important roles in the VOC emissions. At the rural site, almost half of the measured total NMVOCs were due to combustion sources (vehicular and/or biomass/biofuel burning). Petrol evaporation, solvent usage, industrial and biogenic emissions also contributed to the atmospheric NMVOCs. The source apportionment results revealed a strong impact of anthropogenic VOCs to the atmosphere of Hong Kong in both urban/sub-urban and rural areas.

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

“…Benzene, as a carcinogenic compound forbidden to be used in industry, were mainly from automobile exhausts in urban areas [5,24,64], so dominant contribution from vehicle exhausts in the urban site GEMC explained the higher benzene/acetylene ratio than at other sites [5,28]. As toluene, C 8 -aromatics and C 9 -aromatics were widely used as solvents in painting, coating, printing and cleaning processes in the highly industrialized PRD region [3,26,33,67], their high ratios to acetylene at WQS suggested substantial contribution of AHs from industrial emissions in the upwind city of Dongguan, a worldknown manufacturing center in the region. Moreover, the ratios of toluene, C 8 -aromatics and C 9 -aromatics to acetylene at WQS were 1.24 ± 0.13, 0.68 ± 0.07 and 0.20 ± 0.03, consistent with ratios of 1.19, 0.68 and 0.22 previously reported in Dongguan, respectively [5], indicating substantial impacts of emissions from Dongguan on air pollutants occurring at WQS during fall-winter with northeast prevailing winds.…”

“…Nevertheless, −75% to 150% uncertainties still existed for the anthropogenic VOC emission sources [30]. Based on observed data, receptor models including principal component analysis/absolute principal component scores (PCA/APCS) [32,33] and positive matrix factorization (PMF) have been previously applied to explore VOC emission sources based on VOCs measured at four stations with different environments in Hong Kong (HK) during two sampling campaigns [34], at a Hong Kong urban site and a rural site in inland PRD during October-December 2007 [35], and at 84 sites in a grid study with four campaigns during 2008-2009 over the PRD region [36]; and in the inner PRD region sources of VOCs was apportioned by chemical mass balance (CMB) with ambient VOC data observed at fall-winter 2004 [37]. As CMB receptor model are based on the well-known source profiles [38,39], available emission source profiles in the PRD region are neither sufficient nor representative to cover the complicated emission sources in this region.…”

Measuring OVOCs and VOCs by PTR-MS in an urban roadside microenvironment of Hong Kong: relative humidity and temperature dependence, and field intercomparisons

“…As one of the most densely populated cities in the world, Hong Kong has over 7.2 million people and more than 699 540 registered vehicles in an area of 1104 km 2 as of December 2014 (Hong Kong Transport Department, 2014). Special attention has been paid to the characteristics of roadside VOCs and their impacts on the local air quality of Hong Kong during the past years Ho et al, 2004;Guo et al, 2007;Louie et al, 2013;Ling and Guo, 2014). Previous studies have shown that vehicular emissions are one of the major contributors to ambient VOCs in Hong Kong (Guo et al, 2007).…”

“…Special attention has been paid to the characteristics of roadside VOCs and their impacts on the local air quality of Hong Kong during the past years Ho et al, 2004;Guo et al, 2007;Louie et al, 2013;Ling and Guo, 2014). Previous studies have shown that vehicular emissions are one of the major contributors to ambient VOCs in Hong Kong (Guo et al, 2007). Lau et al (2010) found that 31-48 % of ambient VOCs in Hong Kong were generated by vehicle-and marine-vessel-related sources in [2002][2003], and the percentage increased to 40-54 % in 2006-2007. In order to investigate urban roadside VOCs in Hong Kong, multiple sampling and analytical techniques were used, such as offline 2,4-dinitrophenylhydrazine (DNPH) cartridge sampling followed by high-performance liquid chromatography (HPLC) analysis for oxygenated volatile organic compounds (OVOCs); online gas chromatography (GC) with flame ionization detection (FID); and offline canister sampling followed by GC with mass spectrometer detection (MSD), FID, and electron capture detection (ECD) for VOCs Cheng et al, 2014;Ou et al, 2015).…”

Source characteristics of volatile organic compounds during high ozone episodes in Hong Kong, Southern China

“…In the Pearl River Delta region, the speciation and sources of VOC have been studied intensively in some field measurements. For example, Guo et al (2004aGuo et al ( , b, 2006Guo et al ( , 2007 focused on source apportionment of observations of VOC using statistical analyses. Other previous studies were conducted on the ambient levels of VOC in Hong Kong (Sin et al, 2000;Ho et al, 2002;Lee et al, 2002;Wang et al, 2002Wang et al, , 2005So and Wang, 2004;Chan et al, 2006;Tang et al, 2007Tang et al, , 2008Barletta et al, 2008;Liu et al, 2008).…”