The Sichuan Basin is a low visibility area in southwest China, where the hilly and basin topography, plus humid and stagnant weather, lead to unique pollution patterns. To identify the characteristics and sources of carbonaceous aerosols, one-year record of 24-h PM2.5samples were analyzed for organic carbon (OC) and elemental carbon (EC) content following the thermal/optical transmission protocol at three cities (Chengdu (CD), Neijiang (NJ), and Chongqing (CQ)) in the region during May 2012 to April 2013. The annual average concentrations were 19.0 ± 13.3 μg OC m−3 and 4.6 ± 2.6 μg EC m−3 in CD, 18.3 ± 8.4 μg OC m−3 and 4.1 ± 1.8 μg EC m−3 in NJ, and 15.2 ± 8.4 μg OC m−3 and 4.0 ± 1.6 μg EC m−3 in CQ, respectively. Organic matter (1.6OC) plus EC contributed about 40% of PM2.5 mass and displayed weak regional uniformity. Relatively high ratios of OC to EC were observed in the region with 4.3 for CD, 4.6 for NJ, and 3.8 for CQ, respectively. OC and EC pollution in the region exhibited interesting season-dependent characteristics with the lowest concentrations and OC/EC ratios in summer, but higher levels in other seasons. Higher OC/EC ratios in spring and autumn resulted from biomass burning, and in winter were from the enhanced secondary organic aerosol formation under favorable conditions. The exceptionally high OC and EC levels in May and October, mostly notable in CD, resulted from the burning of agricultural residues during harvest period. The high K+concentrations and the high Kexcess/EC ratios implied the persistent influence of biomass burning throughout the year. Using a novel technique combing the EC tracer method and potassium mass balance in the aerosols, a K/EC ratio of 1.22 was used to retrieve the OC from biomass burning and the estimated contributions were 30.8%, 28.3%, and 21.9% in CD, NJ, and CQ, respectively, while secondary OC contributions to OC were 26.7%, 24.6%, and 25.7% in CD, NJ, and CQ, respectively.
Field campaigns monitoring the aerosol optical properties and chemical components of PM10 were carried out in Beijing in 2006 summer. The average light extinction coefficient b(ext), dry aerosol scattering coefficient b(sp) and aerosol absorption coefficient b(ap) were 895.0 +/- 820.8 Mm(-1), 364.0 +/- 324.3 Mm(-1) and 57.8 +/- 31.1 Mm(-1), respectively. b(ext), b(sp) and b(ap) had the similar increasing trend during the formation process of haze. Pronounced diurnal cycles were observed for omega(550) (aerosol single scattering albedo at 550 nm), b(sp), b(ap) and b(ext). The dry b(sp) was elevated during the daytime with a maximum mean value of 475.8 Mm(-1) (LST 06:00). b(ext), PM2.5 mass concentration and PM2.5/PM10 ratio increased at night due to continuous emissions of pollutants to the lower nocturnal boundary layer, and decreased during the daytime due to convective mixing. b(ap) increased at night, and decreased during the daytime and reached the minimum (37 Mm(-1)) at LST 16:00. The single scattering albedo reached its maximum (0.87) at LST 11:00. This trend was consistent with the SNA (sulfate, nitrate, and ammonium)/PM10 ratio and was contrary to the BC (black carbon)/PM10 ratio, which demonstrated that secondary pollution largely influenced the scattering ability of aerosols. Ammonium sulfate, ammonium nitrate, organic mass, elemental carbon and coarse mass contributed 26.5%, 15.2%, 21.8%, 16.1% and 20.4% to the total extinction coefficient during clean days, and 44.6%, 22.3%, 13.6%, 10.8% and 8.7% during hazy days. The fractional contributions of ammonium sulfate and ammonium nitrate were significantly higher during the hazy time than those during the clean days. While the fractional contributions of organic mass, elemental carbon and coarse mass were lower during the haze time than those during the clean days.
Characteristics and sources of particle-bound polycyclic aromatic hydrocarbons (PAHs) in PMin three typical transportation microenvironments were investigated, and the health risks were assessed. Fine particle exposure by pedestrians and commuters taking buses and subways were collected using personal exposure samplers in December 2011 in Beijing. Concentrations of multiple PAHs were measured by gas chromatography-mass spectrometry (GC-MS). Sources of PAHs were identified by distribution patterns and ratios of different PAHs. Health risk assessments associated with respiratory exposure to PAHs were conducted based on benzopyrene (BaP) equivalent concentrations (BEQ), BaP based equivalent carcinogenic power (BaPE) and inhalation cancer risk. The results showed that:1) The average exposure level of PAHs in roadside, buses, and subways were (120±119), (101±46.6), and (50.8±25.6) ng/m, respectively. 2) The similarity of PAHs distribution patterns in the three transportation microenvironments and the ratios of PAHs ρ(Flt)/[ρ(Flt)+ρ(Pyr)] and ρ(IcdP)/[ρ(IcdP)+ρ(BghiP)]>0.5, ρ(BaA)/[ρ(BaA)+ρ(Chr)]>0.35 suggested common sources in these environments, mainly from vehicle emissions and coal combustion. 3) Inhalation cancer risk (19.8×10 -6, California Environmental Protection Agency(CalEPA)-based method; 15.6×10 -4, World Health Organization (WHO)-based method) was found to be highest in the roadside environment, about 1.4 and 3.6 times those for buses and subways, respectively. 4) PAHs were more enriched under the roadside and bus environments. Exposure to PAHs and the health risks obviously increased in the roadside environment during days with elevated PMconcentrations.
Characteristics and sources of particle-bound polycyclic aromatic hydrocarbons ( PAHs) in PM_(2. 5) in three typical transportation microenvironments were investigated,and the health risks were assessed. Fine particle exposure by pedestrians and commuters taking buses and subways were collected using personal exposure samplers in December 2011 in Beijing. Concentrations of multiple PAHs were measured by gas chromatography-mass spectrometry ( GC-MS) . Sources of PAHs were identified by distribution patterns and ratios of different PAHs. Health risk assessments associated with respiratory exposure to PAHs were conducted based on benzo[a]pyrene ( BaP) equivalent concentrations ( BEQ) ,BaP based equivalent carcinogenic power ( BaPE) and inhalation cancer risk. The results showed that: 1) The average exposure level of PAHs in roadside,buses,and subways were ( 120 119) ,( 101 46. 6) ,and ( 50. 8 25. 6) ng/m~3 , respectively. 2) The similarity of PAHs distribution patterns in the three transportation microenvironments and the ratios of PAHs rho( Flt) / [rho( Flt) + rho( Pyr) ]and rho( IcdP) /[rho( IcdP) + rho( BghiP) ]> 0. 5,rho( BaA) /[rho( BaA) + rho( Chr) ]> 0. 35 suggested common sources in these environments,mainly from vehicle emissions and coal combustion. 3 ) Inhalation cancer risk ( 19. 8 * 10 ~(- 6) , California Environmental Protection Agency( CalEPA) -based method; 15. 6 * 10~( - 4),World Health Organization ( WHO) -based method) was found to be highest in the roadside environment,about 1. 4 and 3. 6 times those for buses and subways,respectively. 4) PAHs were more enriched under the roadside and bus environments. Exposure to PAHs and the health risks obviously increased in the roadside environment during days with elevated PM_(2. 5) concentrations.对北京市3种典型交通环境下PM_(2.5)中PAHs(多环芳烃)的污染水平、来源及其暴露健康风险进行了研究.于2011年12月利用颗粒物个体暴露 采样器采集北京市道路边、公共汽车、地铁等不同交通环境下的PM_(2.5)样品,采用GC-MS测定rho(PAHs),结合PAHs组成特征以及特征 化合物比值等鉴别PAHs来源,根据苯并[a]芘等效毒性(BEQ)、等效致癌浓度(BaPE)及致癌风险等参数评估PAHs呼吸暴露的健康风险.结果显 示:1观测期间,北京市道路边、公共汽车和地铁内rho(PAHs)平均值分别为(120119)、(10146.6)、(50.825.6)ng/m~ 3;23种交通环境下PAHs特征成分谱相似,rho(荧蒽)/[rho(荧蒽)+rho(芘)]、rho(茚并[1,2,3-cd]芘)/[rho(茚 并[1,2,3-cd]芘)+rho(苯并[g,h,i]苝)]均大于0.5,rho(苯并[a]蒽)/[rho(苯并[a]蒽)+rho()]大于0. 35,表明机动车尾气和燃煤排放是北京冬季3种交通环境下PAHs的重要贡献源;3分别采用美国加州环境保护局(California Environment Protection Agency,CalEPA)和世界卫生组织(World Health Organization,WHO)方法计算致癌风险可知,2种方法计算的道路边PAHs的致癌风险(19.8*10~(-6)、15.6*10~(-4 ))最高,约为公共汽车及地铁内的1.4和3.6倍;4道路边与公共汽车内的PAHs在PM_(2.5)中更为富集,道路边PAHs污染水平及健康风险在 高rho(PM_(2.5))环境下增加显著.
With rapid economic development and the acceleration of urbanization, air pollution has become a serious problem in the mega-city Guangzhou, China. A field campaign to sample and analyze particulate matter (PM) chemical components was performed from July 6, 2006 to July 26, 2006, in Guangzhou. During the campaign, the average mass concentration of PM10 was 89.0 +/- 46.6 mu g m(-3) (the error represents one standard deviation). The PM10, sulfate, nitrate, ammonium, organic carbon (OC), and elemental carbon (EC) mass frequency distributions were analyzed. The [NO3-]/[SO42-] mass ratio varied from 0.1 to 03, with an average of 0.2. A Pearson correlation analysis between [SO42-] and [NH4+] and between [NO3-] and [Na+] showed that SO42- existed as (NH4)(2)SO4 and NO3- existed as NH4NO3 and NaNO3. Sulfate, nitrate, ammonium, EC and POM (particulate organic matter) accounted for 24.4%, 4.9%, 5.7%, 5.7% and 21.0%, respectively, of the PM10 mass concentration during clean days and 25.7%, 3.9%, 7.9%, 5.4% and 20.8%, respectively, on hazy days. Among these species, SNA (sulfate, nitrate, and ammonium) were the most abundant, accounting for 35.0% and 37.5% of the PM10 during clean and hazy days, respectively. The sum of POM and EC accounted for 26.7% and 26.2% of PM10 in Guangzhou during clean and hazy days, respectively. There was no apparent difference in the chemical composition of PM10 between clean and haze days. (C) 2013 Elsevier B.V. All rights reserved.
Molecular assemblies with well-defined structures capable of photo-induced electron transfer and charge transport or photochemical reactions are reviewed. Hierarchical supramolecular architectures, which assemble the modular units into specific spatial arrangements and facilitate them to work cooperatively, are vital for the achievement of photo-functions in these systems. The chemical design of molecular building blocks and noncovalent interactions exploited to realize supramolecular organizations are particularly discussed. Reviewing and recapitulating the chemical evolution traces of these accomplished systems will hopefully delineate certain fundamental design principles and guidelines useful for developing more advanced functions in the future.
The hygroscopic growth factor (HGF) and cloud condensation nuclei (CCN) activity are measured for surrogates that mimic atmospherically relevant oligomers, including glyoxal trimer dihydrate, methyl glyoxal trimer dihydrate, sucrose, methyl glyoxal mixtures with sulfuric acid and glycolic acid, and 2,4-hexandienal mixtures with sulfuric acid and glycolic acid. For the single-component aerosols, the measured HGF ranges from 1.3 to 1.4 at a relative humidity of 90%, and the hygroscopicity parameter (kappa) is in the range of 0.06 to 0.19 on the basis of the measured CCN activity and 0.13 to 0.22 on the basis of the measured HGF, compared to the calculated values of 0.08 to 0.16. Large differences exist in the. values derived using the measured HGF and CCN data for the multi-component aerosols. Our results reveal that, in contrast to the oxidation process, oligomerization decreases particle hygroscopicity and CCN activity and provides guidance for analyzing the organic species in ambient aerosols.
BACKGROUND: Urbanizing rural areas in China face a rapidly growing cardiovascular disease burden. Epidemiologic studies and effective preventive strategies are urgently needed. METHODS: The Fangshan Cohort Study is a prospective study that began in 2008 and targets local residents aged 40 years or older living in 3 towns in the Fangshan district of Beijing. The baseline examination included a questionnaire on medical history, health knowledge, and behaviors related to cardiovascular disease, as well as physical and blood biochemical examinations. The questionnaire survey will be readministered every 2 years. A system for surveillance of mortality and morbidity of cardiovascular disease is under development. RESULTS: A total of 20 115 adults (6710 men and 13 405 women) were investigated at baseline (participation rate = 84.5%). The data indicate that overweight/obesity is a serious public health issue in Fangshan: average body mass index was 25.4 kg/m(2) among men and 26.5 kg/m(2) among women, and the prevalences of overweight and obesity were 43.6% and 10.3% among men and 47.0% and 17.7% among women. CONCLUSIONS: The Fangshan Cohort Study will provide data on cardiovascular risk factors and disease profile, which will assist in developing appropriate prevention and control strategies for cardiovascular disease in rural Chinese communities.
