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e Pearl River Delta (PRD) of China, which has a population of more than 58 million people, is one of the largest agglomerations of cities in the world and ever experienced severe PM2.5 pollution at the beginning of this century. Due to the implementation of strong pollution control in recent decades, PM2.5 in the PRD has continuously decreased to relatively lower levels in China. To comprehensively understand the current PM2.5 sources in the PRD to support future air pollution control strategy in similar regions, we performed regional-scale PM2.5 field observations coupled with a state-of-the-art source apportionment model at six sites in four seasons in 2015. The regional annual average PM2.5 concentration was determined to be 37 μg/m3, which is still more than three times the WHO standard, with organic matter (36.9 %) and SO4−2 (23.6 %) as the most abundant species. A novel multilinear engine (ME-2) model was then applied to the PM2.5 dataset in the PRD to perform source apportionment with predetermined constraints, which produced more environmentally meaningful results compared to those obtained using traditional positive matrix factorization (PMF) modeling. The regional annual average PM2.5 source structure was retrieved to be secondary sulfate (21 %), vehicle emissions (14 %), industrial emissions (13 %), secondary nitrate (11 %), biomass burning(11 %), secondary organic aerosol (SOA, 7 %), coal burning (6 %), fugitive dust (5 %), ship emissions (3 %) and aged sea salt (2 %). Analyzing the spatial distribution of PM2.5 sources under different weather conditions clearly identified the central PRD area as the key emission area for SO2, NOx, coal burning, biomass burning, industrial emissions and vehicle emissions. It was further estimated that under the polluted northerly air flow in winter, local emissions in the central PRD area accounted for approximately 45 % of the total PM2.5, with secondary nitrate and biomass burning being most abundant; in contrast, the regional transport from outside the PRD accounted for more than half of PM2.5, with secondary sulfate representing the most abundant transported species. [ABSTRACT FROM AUTHOR]

New isonicotinohydrazone compounds, N'-(3-bromobenzylidene)isonicotinohydrazide (1) and N'-(2,3-difluorobenzylidene)isonicotinohydrazide (2), were prepared and structurally characterized by elemental analysis, IR, UV and ¹H NMR spectra, and single crystal X-ray determination. Compound 1 crystallizes in the monoclinic space group P21/n with unit cell dimensions a = 7.600(2) Å, b = 11.365(2) Å, c = 14.412(2) Å, β = 101.748(2)º, V = 1218.7(4) Å3, Z = 4, R1 = 0.0335, and wR2 = 0.0745. Compound 2 crystallizes in the triclinic space group P-1 with unit cell dimensions a = 7.6241(6) Å, b = 11.3937(9) Å, c = 14.335(1) Å, α = 79.664(1)º, β = 75.990(1)º, γ = 71.159(1)º, V = 1136.5(2) ų, Z = 4, R1 = 0.0345, and wR2 = 0.0940. Structures of both compounds are stabilized by hydrogen bonds and π … π interactions. [ABSTRACT FROM AUTHOR]

Aerosol pollution has been a very serious environmental problem in China for many years. The volatility of aerosols can affect the distribution of compounds in the gas and aerosol phases, the atmospheric fates of the corresponding components and the measurement of the concentration of aerosols. Compared to the characterization of chemical composition, few studies have focused on the volatility of aerosols in China. In this study, a TD-AMS (Thermo-Denuder - Aerosol Mass Spectrometer) system was deployed to study the volatility of non-refractory PM1 species during winter in Shenzhen. To our knowledge, this paper is the first report of the volatilities of aerosol chemical components based on a TD-AMS system in China. The average PM1 mass concentration during the experiment was 42.7 ± 20.1 μg m-3, with organics being the most abundant component (43.2 % of the total mass). The volatility of chemical species measured by the AMS varied, with nitrate showing the highest volatility, with an MFR (mass fraction remaining) of 0.57 at 50 °C. Organics showed semi-volatile characteristics (the MFR was 0.88 at 50 °C), and the volatility had a relatively linear correlation with the TD temperature (from 50 to 200 °C), with an evaporation rate of 0.45 %·°C1. Five subtypes of OA were resolved from total OAs by PMF for data obtained under both ambient temperature and high temperatures through the TD, including a hydrocarbon-like OA (HOA, accounting for 13.5 %), a cooking OA (COA, 20.6 %), a biomass burning OA (BBOA, 8.9 %) and two oxygenated OAs (OOA): a less-oxidized OOA (LO-OOA, 39.1 %) and a more-oxidized OOA (MO-OOA, 17.9 %). Different OA species presented different volatilities; the volatility sequence of OA factors at 50 °C was HOA (MFR of 0.56) > LO-OOA (0.70) > COA (0.85) ≈ BBOA (0.87) > MO-OOA (0.99). The volatility sequence of OA components suggested that HOA, rather than BBOA or COA, could be a potentially important source of LO-OOA through the oxidizing process of Evaporation - Oxidation in gas phase - Condensation. The results above can contribute to the understanding of the formation and ageing of submicron aerosols in the atmosphere and will help to constrain aerosol modelling inputs. [ABSTRACT FROM AUTHOR]

The emission of pollutants is extremely reduced during the annual Chinese Spring Festival (SF) in Shenzhen, China. During the SF, traffic flow drops by ~50% and the industrial plants are almost entirely shut down in Shenzhen. To characterize the variation in ambient air pollutants due to the "Spring Festival effect", various gaseous and particulate pollutants were measured in real time in urban Shenzhen over three consecutive winters (2014-2016). The results indicate that the concentrations of NOx, volatile organic compounds (VOCs), black carbon (BC), primary organic aerosols, chloride, and nitrate in submicron aerosols decrease by 50-80% during SF periods relative to non-Spring Festival periods, regardless of meteorological conditions. This decrease suggests that these pollutants are mostly emitted or secondarily formed from urban local emissions. The concentration variation in species mostly from regional or natural sources, however, is found to be much less, such as for bulk fine particulate matter (PM2.5). More detailed analysis of the Spring Festival effect reveals an urgent need to reduce emissions of SO2 and VOCs on a regional scale rather than on an urban scale to reduce urban PM2.5 in Shenzhen, which can also be useful as a reference for other megacities in China. [ABSTRACT FROM AUTHOR]

The emission of pollutants is extremely reduced during the annual Chinese Spring Festival (SF) in Shenzhen, China. During the SF, traffic flow drops by ~ 50 % and the industrial plants are almost entirely shut down in Shenzhen. To characterize the variation in ambient air pollutants due to the Spring Festival effect, various gaseous and particulate pollutants were measured in real time in urban Shenzhen over three consecutive winters (2014-2016). The results indicate that the concentrations of NOx, volatile organic compounds (VOCs), black carbon (BC), primary organic aerosols, chloride, and nitrate in submicron aerosols decrease by 50 %-80 % during the SF period relative to the non-Spring Festival periods, regardless of meteorological conditions, which suggests that these pollutants are mostly emitted or secondarily formed from urban local emissions. The concentration decreasing of regional pollutants or species emitted from natural sources, however, is found to be much less, especially for bulk PM2.5 (-24 %) and O3 (6 %). More detailed analysis of the Spring Festival effect reveals an urgent need to reduce emissions of SO2 and VOCs on a regional scale rather than on an urban scale to reduce urban PM2.5 in Shenzhen, which can also produce some use for reference for other megacities in China. [ABSTRACT FROM AUTHOR]

Although China's severe air pollution has become a focus in the field of atmospheric chemistry and the mechanisms of urban air pollution there have been researched extensively, few field sampling campaigns have been conducted at remote background sites in China, where air pollution characteristics on a larger scale are highlighted. In this study, an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), together with an Aethalometer, was deployed at two of China's national background sites in northern (Lake Hongze site; 33.23° N, 118.33° E; altitude 21 m) and southern (Mount Wuzhi site; 18.84° N, 109.49° E; altitude 958 m) China in the spring seasons in 2011 and 2015, respectively, in order to characterize submicron aerosol composition and sources. The campaign-average PM1 concentration was 36.8±19.8 µgm-3 at the northern China background (NCB) site, which was far higher than that at the southern China background (SCB) site (10.9±7.8 µgm-3/. Organic aerosol (OA) (27.2%), nitrate (26.7%), and sulfate (22.0%) contributed the most to the PM1 mass at NCB, while OA (43.5%) and sulfate (30.5%) were the most abundant components of the PM1 mass at SCB, where nitrate only constituted a small fraction (4.7%) and might have contained a significant amount of organic nitrates (5-11%). The aerosol size distributions and organic aerosol elemental compositions all indicated very aged aerosol particles at both sites. The OA at SCB was more oxidized with a higher average oxygen to carbon (O/C) ratio (0.98) than that at NCB (0.67). Positive matrix factorization (PMF) analysis was used to classify OA into three components, including a hydrocarbon-like component (HOA, attributed to fossil fuel combustion) and two oxygenated components (OOA1 and OOA2, attributed to secondary organic aerosols from different source areas) at NCB. PMF analysis at SCB identified a semi-volatile oxygenated component (SV-OOA) and a lowvolatility oxygenated component (LV-OOA), both of which were found to be secondary species and could be formed from precursors co-emitted with BC. Using the total potential source contribution function model, the likely source areas of the major PM1 components at both sites were a on large regional scale in East Asia. The possible sources may include not only emissions from the Chinese mainland but also emissions from ocean-going cargo ships and biomass burning in neighboring countries. [ABSTRACT FROM AUTHOR]

Although China’s severe air pollution has become a focus in the field of atmospheric chemistry and the mechanisms of urban air pollution there have been researched extensively, few field sampling campaigns have been conducted at remote background sites in China, where air pollut ion characteristics on a larger scale a re highlighted. In this study, an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR–ToF–AMS), together with other relevant instruments, was deployed at two of China’s national background sites in northern (Lake Hongze site) and southern (Mount Wuzhi site) China in the spring season, in order to characterize submicron aerosol composition and sources . The campaign-average PM1 concentration was 36.8 ± 19.8 μg m-3 at the northern China background (NCB) site, which was far higher than that at the southern China background (SCB) site (10.9 ± 7.8 μg m-3). Organic aerosol (OA) (27.2%), nitrate (26.7%), and sulfate (22.0%) contributed the most to the PM1 mass at NCB, while OA (43.5%) and sulfate (30.5%) were the most abundant components of the PM1 mass at SCB, where nitrate only constituted a small fraction (4.7%) and might have contained a significant amount of organic nitrates (5– 11%). The aerosol size distributions and organic aerosol elemental compositions all indicated very aged aerosol partic les at both sites. The OA at SCB was more oxidized with a higher average oxygen to carbon (O/C) rat io (0.98) than that at NCB (0.67), and was found to be the most aged OA in real ambient air ever reported in the literature. Positive matrix factorization analysis (PMF) was used to classify OA into three components , including a hydrocarbon-like component (HOA, attributed to fossil fuel combustion) and two oxygenated components (OOA1 and OOA2, attributed to secondary organic aerosols from different source areas) at NCB. PMF analysis at SCB identified a semi-volatile oxygenated component (SV-OOA) and a low-volatile oxygenated component (LV-OOA), both of which were found to be secondary species and could be formed from precursors co-emitted with BC. Using the total potential source contribution function model, the likely source areas of the major PM1components at both sites were a large regional scale in East Asia. The possible sources may not only include emissions from the Chinese mainland but also include emissions from ocean-going cargo ships and biomass burning in neighboring countries. [ABSTRACT FROM AUTHOR]

The 16th Universiade, an international multi-sport event, was hosted in Shenzhen, China from 12 to 23 August 2011. During this time, officials instituted the Pearl River Delta action plan in order to enhance the air quality of Shenzhen. To determine the effect of these controls, the current study examined the trace elements, water-soluble ions, and stable lead isotopic ratios in atmospheric particulate matter (PM) collected during the controlled (when the restrictions were in place) and uncontrolled periods. Fine particles (PM2.5) were collected at two sampling sites in Shenzhen: "LG"--a residential building in the Longgang District, with significant point sources around it and "PU"--Peking University Shenzhen Graduate School in the Nanshan District, with no significant point sources. Results from this study showed a significant increase in the concentrations of elements during the uncontrolled periods. For instance, samples at the LG site showed (controlled to uncontrolled periods) concentrations (in ng·m-3) of: Fe (152 to 290), As (3.65 to 8.38), Pb (9.52 to 70.8), and Zn (98.6 to 286). Similarly, samples at the PU site showed elemental concentrations (in ng·m-3) of: Fe (114 to 301), As (0.634 to 8.36), Pb (4.86 to 58.1), and Zn (29.5 to 259). Soluble Fe ranged from 7%-15% for the total measured Fe, indicating an urban source of Fe. Ambient PM2.5 collected at the PU site has an average 206Pb/204Pb ratio of 18.257 and 18.260 during controlled and uncontrolled periods, respectively. The LG site has an average 206Pb/204Pb ratio of 18.183 and 18.030 during controlled and uncontrolled periods, respectively. The 206Pb/204Pb ratios at the PU and the LG sites during the controlled and uncontrolled periods were similar, indicating a common Pb source. To characterize the sources of trace elements, principal component analysis was applied to the elements and ions. Although the relative importance of each component varied, the major sources for both sites were identified as residual oil combustion, secondary inorganic aerosols, sea spray, and combustion. The PM2.5 levels were severely decreased during the controlled period, but it is unclear if this was a result of the controls or change in meteorology. [ABSTRACT FROM AUTHOR]

Although China's severe air pollution has become a focus in the field of atmospheric chemistry and the mechanisms of urban air pollution there have been researched extensively, few field sampling campaigns have been conducted at remote background sites in China, where air pollution characteristics on a larger scale are highlighted. In this study, an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), together with other relevant instruments, was deployed at two of China's national background sites in northern (Lake Hongze site) and southern (Mount Wuzhi site) China in the spring season, in order to characterize submicron aerosol composition and sources. The campaign-average PM1 concentration was 36.8 ± 19.8 µg m-3 at the northern China background (NCB) site, which was far higher than that at the southern China background (SCB) site (10.9 ± 7.8 µg m-3). Organic aerosol (OA) (27.2%), nitrate (26.7%), and sulfate (22.0%) contributed the most to the PM1 mass at NCB, while OA (43.5%) and sulfate (30.5%) were the most abundant components of the PM1 mass at SCB, where nitrate only constituted a small fraction (4.7%) and might have contained a significant amount of organic nitrates (5-11%). The aerosol size distributions and organic aerosol elemental compositions all indicated very aged aerosol particles at both sites. The OA at SCB was more oxidized with a higher average oxygen to carbon (O/C) ratio (0.98) than that at NCB (0.67), and was found to be the most aged OA in real ambient air ever reported in the literature. Positive matrix factorization analysis (PMF) was used to classify OA into three components, including a hydrocarbon-like component (HOA, attributed to fossil fuel combustion) and two oxygenated components (OOA1 and OOA2, attributed to secondary organic aerosols from different source areas) at NCB. PMF analysis at SCB identified a semi-volatile oxygenated component (SV-OOA) and a low-volatile oxygenated component (LV-OOA), both of which were found to be secondary species and could be formed from precursors co-emitted with BC. Using the total potential source contribution function model, the likely source areas of the major PM1 components at both sites were a large regional scale in East Asia. The possible sources may not only include emissions from the Chinese mainland but also include emissions from ocean-going cargo ships and biomass burning in neighboring countries. [ABSTRACT FROM AUTHOR]

PM2,5 samples were collected by a three-stage cascade impactor at two kinds of Chinese restaurants to characterize fine organic particulate matter from Chinese cooking sources. Major individual organic compounds have been quantified by GC/MS, including series of aikanes. n-alkanoic acids, n-alkanals, alkan-2-ones and PAHs. Alkanes and ketones make up a significant fraction of particle phase organic compounds, ranging from C11 to C26, and C9 to C19. respectively. In addition, other organic compound classes have been identified, such as alkanols, esters, furans, lactones, amides, and nitriles. The mass concentrations of fine particles, alkanes. n-alkanoic acids and PAHs in air emitted from the Uigur style cooking are hundreds times higher than ambient PM2,5in Beijing. [ABSTRACT FROM AUTHOR]