VOCs and OVOCs distribution and control policy implications in Pearl River Delta region, China

Abstract

h i g h l i g h t s < The first and foremost large spatialetemporal VOCs grid study in the PRD region. < More detailed VOCs spatial emission characteristics were identified. < High OH concentration in PRD favoured fast reactions and ozone formation. < Ozone formation potential of VOCs and OVOCs were analysed. < Findings supported further control measures and policies formulation. a b s t r a c tAmbient air measurements of volatile organic compounds (VOCs) and oxygenated volatile organic compounds (OVOCs) were conducted and characterised during a two-year grid study in the Pearl River Delta (PRD) region of southern China. The present grid study pioneered the systematic investigation of the nature and characteristics of complex VOC and OVOC sources at a regional scale. The largest contributing VOCs, accounting over 80% of the total VOCs mixing ratio, were toluene, ethane, ethyne, propane, ethene, butane, benzene, pentane, ethylbenzene, and xylenes. Sub-regional VOC spatial characteristics were identified, namely: i) relatively fresh pollutants, consistent with elevated vehicular and industrial activities, around the PRD estuary; and ii) a concentration gradient with higher mixing ratios of VOCs in the west as compared with the eastern part of PRD. Based on alkyl nitrate aging determination, a high hydroxyl radical (OH) concentration favoured fast hydrocarbon reactions and formation of locally produced ozone. The photochemical reactivity analysis showed aromatic hydrocarbons and alkenes together consisted of around 80% of the ozone formation potential (OFP) among the key VOCs. We also found that the OFP from OVOCs should not be neglected since their OFP contribution was more than one-third of that from VOCs alone. These findings support the choice of current air pollution control policy which focuses on vehicular sources but warrants further controls. Industrial emissions and VOCs emitted by solvents should be the next targets for ground-level ozone abatement.

The levels, variation characteristics, and sources of atmospheric non-methane hydrocarbon compounds during wintertime in Beijing, China

“…In addition to the hydrocarbon pairs above, the slopes of other hydrocarbon pairs were also analyzed and listed in Table 4. With the exception of the hydrocarbon pairs of propane / toluene, propane / isopentane, propane / n-butane, and propane / isobutane, the slopes of other pairs were within the values reported in different cities Louie et al, 2013). The slopes for the hydrocarbon pairs of propane / toluene, propane / isopentane, propane / n-butane, and propane / isobutane were remarkably greater than those reported in various cities including Beijing, which were suspected to be from the contribution of domestic coal combustion in winter around Beijing (see discussion above).…”

“…Good linear correlations (R 2 ≥ 0.9) between ln [propane] t [propene] t and t were found during the period from 09:00 to 14:00 for most days and during the period of about 00:00-05:00 for most clear days, indicating that the concentration variations in propane and propene basically abided by the chemical kinetic rules above. The OH concentrations were calcu- (Louie et al, 2013). e Results from Houston in 2000 (Jobson et al, 2004).…”

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).…”

“…Because HCHO is carcinogenic (Kerns et al, 1983), it is one of the OVOCs of most interest in urban areas. Only offline DNPH cartridge sampling analyzed by HPLC has previously been used to determine the level of ambient formaldehyde in Hong Kong Guo et al, 2004;Louie et al, 2013;Cheng et al, 2014). PTR-MS was introduced to measure ambient concentrations of formaldehyde continuously in this study.…”

Formaldehyde and Acetaldehyde at Different Elevations in Mountainous Areas in Hong Kong

“…In recent years, efforts have been made to investigate the contributions of primary emissions and secondary formation of HCHO and CH 3 CHO in different environments by using various methods, including the ratios of HCHO/CH 3 CHO, the correlation of HCHO and CH 3 CHO with other tracers, emission inventories, emission-based measurements, and receptor models such as Positive Matrix Factorization (PMF) and PCA/APCS models (Guo et al, 2004;Wei et al, 2008;Li et al, 2010;Wang et al, 2010a;Ho et al, 2012;Parrish et al, 2012;Louie et al, 2013;Dong et al, 2014). For example, by comparing the ratios of HCHO/CH 3 CHO, it was found that the extremely high levels of HCHO (17.3 ppbv) and CH 3 CHO (8.0 ppbv) at a sampling site in the Pearl River Delta region (PRD) on the evening of 15 November 2008 were related to the emissions of biomass burning (Yuan et al, 2012).…”