Characterizations of volatile organic compounds during high ozone episodes in Beijing, China.

Air samples were collected in Beijing from June through August 2008, and concentrations of volatile organic compounds (VOCs) in those samples are here discussed. This sampling was performed to increase understanding of the distributions of their compositions, illustrate the overall characteristics of different classes of VOCs, assess the ages of air masses, and apportion sources of VOCs using principal compound analysis/absolute principal component scores (PCA/APCS). During the sampling periods, the relative abundance of the four classes of VOCs as determined by the concentration-based method was different from that determined by the reactivity approach. Alkanes were found to be most abundant (44.3-50.1%) by the concentration-based method, but aromatic compounds were most abundant (38.2-44.5%) by the reactivity approach. Aromatics and alkenes contributed most (73-84%) to the ozone formation potential. Toluene was the most abundant compound (11.8-12.7%) during every sampling period. When the maximum incremental reactivity approach was used, propene, toluene, m,p-xylene, 1-butene, and 1,2,4-trimethylbenzene were the five most abundant compounds during two sampling periods. X/B, T/B, and E/B ratios in this study were lower than those found in other cities, possibly due to the aging of the air mass at this site. Four components were extracted from application of PCA to the data. It was found that the contribution of vehicle exhaust to total VOCs accounted for 53% of VOCs, while emissions due to the solvent use contributed 33% of the total VOCs. Industrial sources contributed 3% and biogenic sources contributed 11%. The results showed that vehicle exhausts (i.e., unburned vehicle emissions + vehicle internal engine combustion) were dominant in VOC emissions during the experimental period. The solvent use made the second most significant contribution to ambient VOCs.

Polycyclic aromatic hydrocarbons induce endothelial injury through miR-155 to promote atherosclerosis.

Polycyclic aromatic hydrocarbons (PAHs) are considered as an external factor that induces atherosclerotic cardiovascular disease. Although miR-155 is known to be involved in cardiovascular disease, whether it is involved in PAH-induced arteriosclerosis remains unclear. We evaluated the effects of PAHs on vascularization, permeability, and miR-155 expression in HUVECs. We found that PAHs-induced sclerosis of HUVECs was characterized by increasing permeability, decreasing proliferation, and vascular lumen number. The expression of miR-155 was upregulated by PAHs treatment, and transfection with miR-155 inhibitor could reverse above effect of PAHs-induced sclerosis. Meanwhile, transcriptome sequencing revealed that 63 genes were downregulated in the group of PAHs treatment alone, and were then upregulated in the miR-155 inhibitor group. These genes were mainly involved in complement and coagulation cascades, cytokine-cytokine receptor interaction, TNF signaling pathway, and NF-kappa B signaling pathway. Among these 63 genes, SERPIND1 was directly targeted and regulated by miR-155. Further in vivo experiments in ApoE-/- mice confirmed that PAH accelerates the development of arteriosclerosis by promoting the expression of miR-155 to downregulate the SERPIND1. Therefore, PAH exaggerates atherosclerosis by activating miR-155-dependent endothelial injury. This study provides a fundamental insight on the miR-155 mechanism for PAHs enhancing atherosclerosis and miR-155 potentially serving as a novel drug target.

[Concentration Characteristics and Sources of Trace Metals in PM2.5 During Wintertime in Beijing].

To study the characteristics and sources of trace metals in PM2.5 during wintertime in Beijing, PM2.5 samples were collected from December 2014 to January 2015 by a middle volume sampler in the urban area of Beijing for 30 consecutive days. The mass concentration of PM2.5 was measured by filter membrane weighting method, and 16 kinds of trace metals were determined by inductively couple plasma-mass spectrometry (ICP-MS). In addition, the pollution characteristics and sources of trace metals were analyzed by enrichment factor (EF) method and factor analysis, respectively. The results showed that the concentrations of five elements (i. e. K, Ca, Fe, Al and Mg) accounted for 90.7% of the total metal elements. The concentrations of the metal elements changed obviously between day and night. Compared with daytime, crustal elements like Mg and Al decreased by more than 30% while anthropogenic elements like Cu and Pb increased by more than 40% in nighttime. Although the concentrations of metal elements increased by nearly one time in heavy pollution days compared with clean days, the mass percent of which in PM2.5 decreased from 10.9% in clean days to 4.6% in heavy pollution days. This result suggested the accumulation of metal elements in heavy pollution days had a minor contribution to the increased mass concentration of PM2.5. As the pollution episode progressed, anthropogenic elements (Cu,Zn,As,Se,Ag and Cd) increased faster than crustal elements (Al,Mg,Ca,Mn and Fe), which showed ratios ranging from 2.9 to 5.3 for anthropogenic elements and ratios ranging from 1.2 to 1.8 for crustal elements, when compared between heavy pollution days and clean days. In addition, the EF value of anthropogenic elements was also increased in the pollution days, indicating the concentrations of these elements was further influenced by the anthropogenic sources. Factor analysis showed that metal elements of PM2.5 during wintertime of Beijing were mainly from coal combustion and biomass burning, motor vehicle and industry emissions, and re-suspension of road dust, with the contributions of 34.2%,25.5% and 17.1%, respectively.

[Variation Characteristics and Sources Analysis of Atmospheric Volatile Organic Compounds in Changbai Mountain Station].

Volatile organic compounds (VOCs) play very important roles in the formation of ozone and secondary organic aerosols. The concentrations, compositions, and seasonal variation of VOCs were measured in 2012 at Changbai Mountain Forest Ecosystem Research Station, a remote station in Northeast China. Weekly samples were collected in the Changbai Mountain area and analyzed via gas chromatography-mass spectrometry. The results showed that the annual mean concentration of total VOCs (TVOCs) was 10.7×10-9±6.2×10-9. Halohydrocarbon was the most abundant component, accounting for 37% of the total VOCs, followed by alkanes and aromatics, accounting for 33% and 15% respectively, and alkenes accounted for 15%. The seasonal variation of TVOCs in this area was obvious, and the order was spring >autumn >summer >winter. TVOCs concentration in spring was very significantly higher than those in any other season (P<0.05). The principal component analysis (PCA) was used to identify the sources of the VOCs. Five sources were resolved by the PCA, including traffic sources, LPG,biogenic sources, combustion sources, industrial sources and regional transportation. The HYSPLIT-4.0 model was used to analyze the effect of pollutant transport, and the results indicated that the transport of pollutants from southwest had a significant effect on the increase of VOCs concentration.

Odor composition analysis and odor indicator selection during sewage sludge composting.

UNLABELLED: On the basis of total temperature increase, normal dehydration, and maturity, the odor compositions of surface and internal piles in a well-run sewage sludge compost plant were analyzed using gas chromatography-mass spectrometry with a liquid nitrogen cooling system and a portable odor detector. Approximately 80 types of substances were detected, including 2 volatile inorganic compounds, 4 sulfur organic compounds, 16 benzenes, 27 alkanes, 15 alkenes, and 19 halogenated compounds. Most pollutants were mainly produced in the mesophilic and pre-thermophilic periods. The sulfur volatile organic compounds contributed significantly to odor and should be controlled primarily. Treatment strategies should be based on the properties of sulfur organic compounds. Hydrogen sulfide, methyl mercaptan, dimethyl disulfide, dimethyl sulfide, ammonia, and carbon disulfide were selected as core indicators. Ammonia, hydrogen sulfide, carbon disulfide, dimethyl disulfide, methyl mercaptan, dimethylbenzene, phenylpropane, and isopentane were designated as concentration indicators. Benzene, m-xylene, p-xylene, dimethylbenzene, dichloromethane, toluene, chlorobenzene, trichloromethane, carbon tetrachloride, and ethylbenzene were selected as health indicators. According to the principle of odor pollution indicator selection, dimethyl disulfide was selected as an odor pollution indicator of sewage sludge composting. Monitoring dimethyl disulfide provides a highly scientific method for modeling and evaluating odor pollution from sewage sludge composting facilities. IMPLICATIONS: Composting is one of the most important methods for sewage sludge treatment and improving the low organic matter content of many agricultural soils. However, odors are inevitably produced during the composting process. Understanding the production and emission patterns of odors is important for odor control and treatment. Core indicators, concentration indicators, and health indicators provide an index system to odor evaluation. An odor pollution indicator provides theoretical support for further modelling and evaluating odor pollution from sewage sludge composting facilities.

[Study on atmospheric VOCs in Gongga Mountain base station].

Volatile organic compounds (VOCs) play important roles in the atmosphere as precursors of secondary air pollutants. The regional background concentrations and variation characteristics of VOCs in the atmosphere of southwestern China were studied. Meanwhile, a receptor model based on principal component analysis (PCA) was used to identify the major sources of VOCs. Weekly samples were collected in 2007 in the Gongga Mountain base station and analyzed with a three-stage preconcentration method coupled with GC-MS. The annual mean concentration of TVOCs and NMHCs were 9.40 x 10(-9) +/- 4.55 x 10(-9) and 7.73 x 10(-9) +/- 4.43 x 10(-9), respectively. Aromatic hydrocarbons provided the largest contribution to TVOCs (37.3%), follow by alkanes (30.0%) and halogenated hydrocarbons (19.8%), the smallest contribution was from alkenes (12.9%). Three major sources were resolved by the receptor model, traffic sources, biogenic sources and combustion sources. The seasonal variation of TVOCs in this area was obviously, and the order was autumn > winter > spring > summer. TVOCs concentration in autumn was very significantly higher than that in summer (P < 0.01). The seasonal variation of the four types of VOCs showed different characteristics due to the differences in photochemical properties. Isoprene emissions were from biogenic sources. Regression analysis revealed a good exponential relationship between the isoprene concentration and temperature. High temperatures increased the isoprene concentrations. However, the isoprene concentration remained constant when the ambient air temperature was below 20 degrees C. The TVOCs in Gongga Mountain were at a medium level comparing with the results of other regions, and there was a clear background station emission characteristic.

[Analysis on status pollution and variation of BTEX in Beijing].

In order to study the pollution status and the seasonal and diurnal variations, ambient concentrations of BTEX were analyzed at Beijing from 2008-10 to 2009-10, by using the method of two-step-concentration-gas spectrometry/mass (CCD-GC/MS). The average concentration of BTEX in Beijing was 13.9-44.0 microg x cm(-3). The dominant compound components were toluene, benzene, followed by ethyl benzene, m/p-xylene, o-xylene. Compared with foreign cities and regions, the level of BTEX at Beijing atmosphere was relatively lower. The study found that BTEX in Beijing mainly came from vehicle emissions, coal and solvent evaporation were also important sources of BTEX. No significantly obvious seasonal variation was observed, with the highest concentrations observed in spring and summer and the lowest concentrations generally found in autumn. Seasonal variations of emission sources were the main reason for seasonal changes of BTEX. However, the impact of weather factors on the BTEX can not be ignored, such as temperature and strong winds. Significant diurnal variations in BTEX were observed. The BTEX concentrations displayed a bimodal pattern, with peak between 08:00 and 10:00. and between 16:00 and 08:00. The minimum concentration generally appeared around 14:00.

[Observation and study on atmospheric VOCs in Changsha city].

Volatile organic compounds (VOCs) are one of the key precursors of atmospheric ozone (O3), which also contribute to the production of SOA. During 2008, VOCs were measured near Changsha City. Weekly integrated canister samples were collected and analyzed in the morning and afternoon of each Tuesday. Simultaneously, concentration, potential ozone production and sources of VOCs in the atmosphere of Changsha were studied. The results indicated that the total VOCs species had higher concentrations in the morning (38.4 x 10(-9)), and lower in the afternoon (22.7 x 10(-9)), where the concentration of halo carbon was the highest, and alkanes, aromatics and alkenes came next. The m/p-xylene had the highest OH reactivity concentration (10.71 x 10(-9) C), 1,2,4-trimethylbenzene (6.04 x 10(-9) C) and 1,3,5-trimethylbenzene (2.23 x 10(-9) C) came next. Aromatics (66%) had the most significant contribution to the production of O3 in the atmospheric VOCs of Changsha, and alkenes (26%) and alkanes (8%) came next. The highest concentrations of propane and isopentane indicated vehicular exhaust and liquefied petroleum gas (LPG) appear to be the main source of VOCs in Changsha City. Benzene/toluene ratio was higher than 0.5 which was close to 0.8, showing solvent volatilization was also a main source of VOCs.

[Concentration and change of VOCs in summer and autumn in Tangshan].

In order to study the potential impact of volatile organic compounds (VOCs) in summer and autumn on region ozone, ambient concentrations and changes of VOCs were analyzed at Tangshan from June to September 2007 and 2008, by using the method of two-step-concentration-gas spectrometry/mass (CCD-GC/MS). The average concentration in Tangshan was 163.5 x 10(-9) C. The major components were alkanes, aromatics, alkenes and halogen hydrocarbons which accounted for 45.9%, 29.9%, 5.9% and 18.9% respectively. The average concentration decreased 51.9% compare with 2007 (340.4 x 10(-9) C), confine gas stations is the main reason of the decline of alkyl, the large decline is aromatic hydrocarbons, 67%, which has the most potential impact of ozone formation, and dichlorobenzene in industrial emissions has increased. The concentrations of VOCs in Tangshan were lower 8% than that of Beijing during the same period in 2008. The changes of VOCs during 2008 Beijing Olympic show that in addition to traffic source industrial emissions is also an important source of atmospheric pollution.

[Study on concentration, ozone production potential and sources of VOCs in the atmosphere of Beijing during Olympics period].

Volatile organic compounds (VOCs) is one of the key precursors of atmospheric ozone (O3), whose concentration variation influences directly the level of the photochemical pollutant O3. During Beijing Olympics, VOCs were measured near the Beijing National Stadium. Two and half-hour integrated canister samples were collected and analyzed in the morning and afternoon of each sampling day. Simultaneously, concentration, potential ozone production and sources of VOCs in the atmosphere of Beijing were studied. And the results indicated that the total VOCs species had higher concentrations in the morning (34.38 x 10(-9)), and lower in the afternoon (27.13 x 10(-9)), where the concentration of alkanes was the highest, and aromatics and alkenes came next. However, the concentrations of alkenes in the afternoon were significantly lower than those in the morning, which was 28%, and aromatics (26%) and alkanes (15%) came next. 1,2,4-Trimethylbenzene has the highest propylene-equivalent concentration (8.05 x 10(-9)C), and m/p-xylene (6.97 x 10(-9)C), toluene (6.41 x 10(-9)C) and 1,3,5-trimethylbenzene (5.64 x 10(-9) C) came next. Aromatics (47%) gives the most significant contribution to the production of O3 in the atmospheric VOCs of Beijing, and then were alkenes (40%) and alkanes (13%). Automobile emissions accounted for approximately 28% of the total VOCs, and solvent volatilization (19%), LPG leakage (15%) and industrial sources (12%) came next, from which Beijing may decrease the atmospheric VOCs.

[Concentrations and size distributions of water soluble ions of atmospheric aerosol at the summit of mount Tai].

In order to research on the air pollutants' long-range transportation in North China, aerosol samples were collected with Andersen cascade sampler at the summit of mount Tai during June 2006, in Shandong Province. The water soluble ionic concentrations were analyzed by IC. It shows that there are three types of size distribution: 1) ions whose mass resided mainly within the accumulation mode with the peak at 0.43-0.65 microm (SO4(2-), NH4+, K+); 2) Ions whose mass resided mainly within coarse particles with the peak at 4.7-5.8 microm (Ca2+, Mg2+); 3) Ions which were two modes with the peak at 0.43-0.65 microm and 4.7-5.8 microm (NO3-, NO3-,Cl-). The mass median diameter of SO4(2-) with high concentration is between 0.5 microm and 0.8 microm, and belongs to the "drop mode". The concentration of ions such as SO4(2-), NO3-, NH4+ and K+ has a huge variety and the sulfate has the most great variety with the lowest concentration which is 4.0 microg x m(-3) and the highest concentration which is 42.3 microg x m(-3). The ions (SO4(2-), NO3-, NH4+) reach the high value when the humid air mass comes from the south.