Previous studies have investigated the associations between exposure to ambient air pollution and biomarkers of physiological pathways, yet little has been done on the comparison across biomarkers of different pathways to establish the temporal pattern of biological response. In the current study, we aim to compare the relative temporal patterns in responses of candidate pathways to different pollutants. Four biomarkers of pulmonary inflammation and oxidative stress, five biomarkers of systemic inflammation and oxidative stress, ten parameters of autonomic function, and three biomarkers of hemostasis were repeatedly measured in 125 young adults, along with daily concentrations of ambient CO, PM2.5, NO2, SO2, EC, OC, and sulfate, before, during, and after the Beijing Olympics. We used a two-stage modeling approach, including Stage I models to estimate the association between each biomarker and pollutant over each of 7 lags, and Stage II mixed-effect models to describe temporal patterns in the associations when grouping the biomarkers into the four physiological pathways. Our results show that candidate pathway groupings of biomarkers explained a significant amount of variation in the associations for each pollutant, and the temporal patterns of the biomarker-pollutant-lag associations varied across candidate pathways (p<0.0001) and were not linear (from lag 0 to lag 3: p = 0.0629, from lag 3 to lag 6: p = 0.0005). These findings suggest that, among this healthy young adult population, the pulmonary inflammation and oxidative stress pathway is the first to respond to ambient air pollution exposure (within 24 hours) and the hemostasis pathway responds gradually over a 2-3 day period. The initial pulmonary response may contribute to the more gradual systemic changes that likely ultimately involve the cardiovascular system.
Emissions factors (EFs) for gas and sub-micron particle-phase species were measured in intercepted plumes as a function of vessel speed from an underway research vessel, the NOAA ship Miller Freeman, operating a medium-speed diesel engine on low-sulfur marine gas oil (fuel sulfur content similar to 0.1% by weight). The low-sulfur fuel in use conforms to the MARPOL fuel sulfur limit within emission control areas set to take effect in 2015 and to California-specific limits set to take effect in 2014. For many of the particle-phase species, EFs were determined using multiple measurement methodologies, allowing for an assessment of how well EFs from different techniques agree. The total sub-micron PM (PM1) was dominated by particulate black carbon (BC) and particulate organic matter (POM), with an average POM/BC ratio of 1.3. Consideration of the POM/BC ratios observed here with literature studies suggests that laboratory and in-stack measurement methods may overestimate primary POM EFs relative to those observed in emitted plumes. Comparison of four different methods for black carbon measurement indicates that careful attention must be paid to instrument limitations and biases when assessing EFBC. Particulate sulfate (SO42-) EFs were extremely small and the particles emitted by Miller Freeman were inefficient as cloud condensation nuclei (CCN), even at high super saturations, consistent with the use of very low-sulfur fuel and the overall small emitted particle sizes. All measurement methodologies consistently demonstrate that the measured EFs (fuel mass basis) for PM1 mass, BC and POM decreased as the ship slowed. Particle number EFs were approximately constant across the speed change, with a shift towards smaller particles being emitted at slower speeds. Emissions factors for gas-phase CO and formaldehyde (HCHO) both increased as the vessel slowed, while EFs for NOx decreased and SO2 EFs were approximately constant.
To track the chemical characteristics and formation mechanism of biomass burning pollution, the hourly variations of meteorological factors and pollutant concentrations during a heavy pollution on 18–21 May, 2012 in Chengdu are presented in this study. The episode was the heaviest and most long-lasting pollution event in the historical record of Chengdu caused by a combination of stagnant dispersion conditions and enhanced PM2.5 emission from intensive biomass burning, with peak values surpassing 500 μg m− 3. The event was characterized by three nighttime peaks, relating to the burning practice and decreased boundary layer height at night. The prevailing northeasterly wind during nighttime preferentially brought more pollutants to the urban regions from northern suburbs of Chengdu, where dense fire spots were observed. Due to the obstruction of hilly topography and weak wind speed, minor regional features were reflected from the PM10 variations in nearby cities, whereas the long-distance transport of the plume impacted extensive regions in northern and eastern China. Carbon monoxide (CO) concentrations increased by more than 200%, while exceptionally high PM2.5 levels of 190.1 and 268.4 μg m− 3 on 17 May and 18 May, were observed and showed high correlation with CO (r = 0.75). The relative contribution of biomass burning smoke to organic carbon was estimated from OC/EC ratios (organic carbon/elemental carbon) and elevated to 81.3% during the episode, indicating a significant impact on urban aerosol levels. The occurrence of high PM2.5/PM10 ratios (> 0.80) and K+/EC ratios (> 1.0), along with the increased carbonaceous concentrations and their fraction in PM2.5 (> 40%) and high OC/EC ratios (about 8), could be used as immediate indicators for biomass burning pollution in cities. In addition, the heavy pollution involved a mixture of anthropogenic sources, reflected from the high SOR and NOR values and increases in the EFs (enrichment factors) of Mo, Zn, Cd, and Pb.
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.
