[Ratios of Volatile Organic Compounds in Ambient Air of Various Cities of China].

Volatile organic compounds (VOC) ratios in urban atmosphere could provide important information on VOC data quality, sources, and options for removal processes. Based on seven VOC measurement datasets, useful VOC ratios were calculated using four methods, including orthogonal distance(ODR), linear regression, geometric mean, mean, and frequency distribution. Ambient levels of m,p-xylene and o-xylene from the seven datasets showed good correlation with r ranging from 0.975 to 0.997, and their ratios (m,p-xylene/o-xylene) were close, with values of 2.78-3.05, indicating therefore that the ratio of m,p-xylene/o-xylene could be used to evaluate the quality of ambient measurement data in urban atmospheres. In addition, ratios of toluene versus benzene (T/B) and propane versus ethane (P/E) in different cities were compared, to investigate VOC sources in China. The highest T/B ratios were found in Shanghai and Guangzhou City, with values of 2.37 and 1.78, respectively, higher than the result from a tunnel study (1.52), suggesting the important influence of paint and solvent use. The T/B value for Beijing City during summer was close to that from the tunnel study, while the T/B ratios for Chengdu, Beijing during winter, and Chongqing were lower, with values ranging from 0.744 to 1.36, suggesting possible influences from biomass burning and coal combustion. The P/E value in Guangzhou was 1.27, significantly higher than the range of 0.270 to 0.645 found in other cities. The OH exposure in different cities were calculated based on o-xylene/ethylbenzene (X/E), with values ranging from 2.70×1010 to 4.45×1010 molecule·cm-3·s.

[Process-based Emission Characteristics of Volatile Organic Compounds (VOCs) from Paint Industry in the Yangtze River Delta, China].

Understanding the volatile organic compounds (VOCs) emission characteristics from solvent usage industry is essential to reduce PM2.5 and O3 in Yangtze River Delta region. In this work, VOCs source characteristics of ship container, shipbuilding, wood, and automobile painting industry were measured using canister-GC-MS/FID analysis system. The results showed that VOCs emitted from these industrial sectors were mainly aromatics, such as toluene, xylene, and ethylbenzene, accounting for 79%-99% of total VOCs. The VOCs treatment facilities of activated carbon adsorption had little impact on changing the composition patterns of VOCs, while catalytic combustion treatments produced more alkenes. The combustion treatment of VOCs changed the maximum increment reactivity (MIR) of the VOCs emissions, and was thus very likely to change the ozone formation potentials.

[Characterizing spatial patterns of NO(x), SO2 and O3 in Pearl River Delta by passive sampling].

Concentrations of NO(x), SO2 and O3 were measured by passive sampling within 200km x 200km grid in Pearl River Delta (PRD). Sampling period was two weeks in November, 2009. Spatial distributions of NO(x), SO2 and O3 were obtained by Kriging interpolation method. The results were compared with emission inventories and modeling results. The transportations of O3 were evaluated by using backward trajectories of air parcels. During the sampling period, the mean concentrations of NO(x), SO2 and O3 were 75.9 microg/m3, 37.3 microg/m3 and 36.2 microg/m3, respectively. And the highest concentrations of NO(x), SO2 and O3 were 195.7 microg/m3, 95.9 microg/m3 and 81.8 microg/m3. Comparing with routine measurements from the regional monitoring network in PRD, the results by passive method were 18.6%, 33.5% and 37.5% lower for NO(x), SO2 and O3, respectively. The spatial patterns demonstrated that higher NO(x) concentrations often appeared in cities such as Guangzhou, Foshan and Shenzhen. SO2 concentrations were higher in west and lower in east. High SO2 concentrations are mainly from emission of power plants and industrial sources. Concentrations of O3 showed the highest levels in the south of PRD. Backward trajectory analysis for higher ozone areas indicated that 53% of the air masses were from the region with high concentration of NO(x). The horizontal transportation caused higher ozone in the south while lower in north in PRD.

[Spatial and temporal variations of ambient carbonyl compounds in Beijing and its surrounding areas].

Concentrations of 23 carbonyl compounds were measured by DNPH/HPLC method at 38 sites within Beijing and its surrounding areas on June 24, July 22, August 22, September 14 in 2010 and January 13, 2011. The average mixing ratios of total carbonyl compounds in Beijing were (16.38 +/- 6.03) x 10(-9) and (8.50 +/- 5.27) x 10(-9) in summer and winter; and the average mixing ratios in surrounding cites were (13.19 +/- 5.71) x 10(-9) and (13.05 +/- 2.44) x 10(-9) in summer and winter, respectively. The most abundant carbonyl compound was formaldehyde, followed by acetaldehyde and acetone, the sum of these 3 species accounted for 78% to 91% of the total mixing ratio of carbonyl compounds. The average mixing ratio in summer was significant higher than that in winter, and higher in morning (09:00-12:00) hours than in afternoon (13:00-16:00). The spatial distributions for carbonyl compounds showed that: in summer, high mixing ratios were typically found in city center; while in winter, a building-up trend was found from northwest to southeast, driving by the prevailing northwest wind. In summer, vehicular exhaust had important contributions to ambient carbonyls, and combined with the adverse weather conditions and the strong photochemical production, resulted in carbonyls pollutions; in winter, directly emissions were the main sources of carbonyls, such as vehicular exhaust and coal burning.

[Relationship between atmospheric particles and rain water chemistry character].

Rain and atmospheric particle samples were collected in the rural area of Taian and Shenzhen in 2007, respectively. Rain sampling was carried out during the precipitation process and several samples were got from the beginning of one precipitation to the end. The chemical character changes during precipitation and the changes of concentration of particles before and after rain were studied in this research to understand the contribution of particles on the rain chemical character and the rain-out effect for particles. The volume-weighted mean pH of rainwater in Taian was 5.97 and the total concentration of ions was 1 187.96 microeq x L(-1). The mass concentration of PM10 in Taian was 131.76 microg/m3 and that of PM2.5 was 103.84 microg/m3. The volume-weighted mean pH of rainwater in Shenzhen was 4.72 and the total concentration of ions was 175.89 microeq x L(-1). The mass concentration of PM10 in Shenzhen was 56.66 microg/m3 and that of PM2.5 was 41.52 microg/m3. During precipitation process pH and ion concentration of rain decrease and it is shown the neutralizing effect happens. The difference between rainwater of Taian and Shenzhen is due to cloud water acidity, atmospheric particles character and atmospheric acid-basic gases concentration. The clean-up effect of Na+ and Ca2+ by rain is high and which of NH4+ and NO3- is low. The clean-up effect for mass concentration, ions concentration and element concentration of particles by rain are significant.

[Identification of air toxics from indoor and outdoor measurements of volatile organic compounds in one elementary school in Beijing].

Concentrations and characteristics of 82 volatile organic compounds (VOCs) were measured in indoor and outdoor air in one elementary school of Beijing by method TO14/15 recommended by USEPA in 2007 summer. And the toxic VOCs for children's health were identified. The study illuminates that the concentration level of total VOCs were higher in indoor air than in outdoor air. Alkanes were most abundant VOCs species accounting for 32.8% of total measured VOCs on average. The chemical speciation of VOCs in indoor air was similar to the outdoor, and the dominant species were isopentane, benzene, toluene, propanal, propene and dichloromethane. In the indoor air, m/p-dichlorobenzene and cyclohexane likely came from indoor sources, proved by the indoor/outdoor concentration ratios of p-dichlorobenzene (65.8) and cyclohexane (10.5), and the large distance between the concentrations of m-dichlorobenzene in indoor air (2.02 x 10(-9)) and outdoor (lower than the detected limit) air. 1, 3-butadiene, chloride vinyl, benzene and chloromethane, whose average cancer risk values were 1.3 x 10(-5), 6.4 x 10(-6), 5.1 x 10(-6) and 3.3 x 10(-6) respectively, exceeded the cancer risk value 1 x 10(-6) in all samples sites. The cumulative cancer risk in indoor air, outdoor air and children house were 24-39 times bigger than 1 x 10(-6). Acrolein was the only non-carcinogenic hazardous species which exceeded its benchmark concentration by 13-72 times in all sites.