Seasonal variations of monosaccharide anhydrides in PM1 and PM2.5 aerosol in urban areas

The concentrations of monosaccharide anhydrides (levoglucosan, mannosan, galactosan) in PM1 and PM2.5 aerosol samples were measured in Brno and ?lapanice in the Czech Republic in winter and summer 2009. 56 aerosol samples were collected together at both sites to investigate the different sources that contribute to aerosol composition in studied localities. Daily PM1 and PM2.5 aerosol samples were collected on pre-fired quartz fibre filters.The sum of average atmospheric concentration of levoglucosan, mannosan and galactosan in PM1 aerosol in ?lapanice and Brno during winter was 513 and 273 ng m^?3, while in summer the sum of average atmospheric concentration of monosaccharide anhydrides (MAs) was 42 and 38 ng m^?3, respectively. The sum of average atmospheric concentration of MAs in PM1 aerosol formed 71 and 63% of the sum of MA concentration in PM2.5 aerosol collected in winter in ?lapanice and Brno, whereas in summer the sum of average atmospheric concentration of MAs in PM1 aerosol formed 45 and 43% of the sum of MA concentration in PM2.5 aerosol in ?lapanice and Brno, respectively.In winter, the sum of MAs contributed significantly to PM1 mass ranging between 1.37% and 2.67% of PM1 mass (Brno – ?lapanice), while in summer the contribution of the sum of MAs was smaller (0.28–0.32%). Contribution of the sum of MAs to PM2.5 mass is similar both in winter (1.37–2.71%) and summer (0.44–0.55%).The higher concentrations of monosaccharide anhydrides in aerosols in ?lapanice indicate higher biomass combustion in this location than in Brno during winter season. The comparison of levoglucosan concentration in PM1 and PM2.5 aerosol shows prevailing presence of levoglucosan in PM1 aerosol both in winter (72% on average) and summer (60% on average).The aerosol samples collected in ?lapanice and Brno in winter and summer show comparable contributions of levoglucosan, mannosan and galactosan to the total amount of monosaccharide anhydrides in both aerosol size fractions. Levoglucosan was the most abundant monosaccharide anhydride with a relative average contribution to the total amount of MAs in the range of 71–82% for PM1 aerosols and 52–79% for PM2.5 aerosols.     

Temporal variations of atmospheric carbonyls in urban ambient air and street canyons of a Mountainous city in Southwest China

Carbonyl compounds in urban ambient air and street canyons were measured from December 2008 to August 2009 in a mountainous city in southwest China (Guiyang). The formaldehyde yield from the photo-oxidation of isoprene emitted by vegetation was estimated to be in the range of 0.63–3.62 μg m^?3 from May to August, which accounted for 28.8–33.4% of ambient formaldehyde. Based on the calculation of photolysis rates and rates of reaction with the OH radical, it was found that photolysis was the predominant sink for formaldehyde and acetone in both summer and winter. For acetaldehyde, photo-oxidation by OH radicals and photolysis were the major sinks in summer while photo-oxidation by OH radicals was the dominant sink in winter. Wet precipitation was found to be an important removal process for the atmospheric carbonyls. In the urban ambient air, the average concentrations of formaldehyde, acetaldehyde, acetone and all carbonyls were 4.8 ± 2.1, 5.7 ± 3.3, 5.1 ± 2.5, and 25.1 ± 9.2 μg m^?3 (n = 139), respectively. The average concentrations of these species in street canyons were 18.8 ± 6.5, 9.4 ± 3.2, 10.9 ± 2.1, and 64.1 ± 16.3 μg m^?3 (n = 62), respectively. The significantly higher carbonyl levels on weekdays (compared to weekends) highlight the contribution of vehicle emissions to carbonyls in the street canyons.     

Temporal variations of surface water quality in urban, suburban and rural areas during rapid urbanization in Shanghai, China

As the economic and financial center of China, Shanghai has experienced an extensive urban expansion since the early 1980s, with an attendant cost in environmental degradation. We use an integrated pollution index to study the temporal variations of surface water quality in urban, suburban and rural areas between 1982 and 2005. Data on monitored cross-sections were collected from the Shanghai Environmental Monitoring Center. The results indicated that the spatial pattern of surface water quality was determined by the level of urbanization. Surface water qualities in urban and suburban areas were improved by strengthening the environmental policies and management, but were worsening in rural areas. The relationship between economic growth and surface water quality in Shanghai showed an inversed-U-shaped curve, which reflected a similar pattern in most developed countries. This research suggests that decision makers and city officials should be more aware of the recent pollution increases in Shanghai.     

Characterization of PM10 atmospheric aerosol at urban and urban background sites in Fuzhou city, China

Background

PM₁₀ aerosol samples were simultaneously collected at two urban and one urban background sites in Fuzhou city during two sampling campaigns in summer and winter. PM₁₀ mass concentrations and chemical compositions were determined.

Methods

Water-soluble inorganic ions (Cl^?, NO ₃ ^? , SO ₄ ^2? , NH ₄ ⁺ , K⁺, Na⁺, Ca²⁺, and Mg²⁺), carbonaceous species (elemental carbon and organic carbon), and elements (Al, Si, Mg, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Br, and Pb) were detected using ion chromatography, thermal/optical reflectance, and proton-induced X-ray emission methods, respectively.

Results

PM₁₀ mass concentrations, as well as most of the chemical components, were significantly increased from urban background to urban sites, which were due to enhanced anthropogenic activities in urban areas. Elements, carbonaceous species, and most of the ions were more uniformly distributed at different types of sites in winter, whereas secondary ion SO ₄ ^2? , NO ₃ ^? , and NH ₄ ⁺ showed more evident urban-background contrast in this season. The chemical mass closure indicated that mineral dust, organic matters, and sulfate were the most abundant components in PM₁₀. The sum of individually measured components accounted for 86.9?C97.7% of the total measured PM₁₀ concentration, and the discrepancy was larger in urban area than in urban background area.

Conclusion

According to the principal component analysis?Cmultivariate linear regression model, mineral dust, secondary inorganic ions, sea salt, and motor vehicle were mainly responsible for the PM₁₀ particles in Fuzhou atmosphere, and contributed 19.9%, 53.3%, 21.3%, and 5.5% of PM₁₀, respectively.     

Road traffic impact on urban atmospheric aerosol loading at Oporto,Portugal

At urban areas in south Europe atmospheric aerosol levels are frequently above legislation limits as a result of road traffic and favourable climatic conditions for photochemical formation and dust suspension. Strategies for urban particulate pollution control have to take into account specific regional characteristics and need correct information concerning the sources of the aerosol.With these objectives, the ionic and elemental composition of the fine (PM_2.5) and coarse (PM_2.5–10) aerosol was measured at two contrasting sites in the centre of the city of Oporto, roadside (R) and urban background (UB), during two campaigns, in winter and summer.Application of Spatial Variability Factors, in association with Principal Component/Multilinear Regression/Inter-site Mass Balance Analysis, to aerosol data permitted to identify and quantify 5 main groups of sources, namely direct car emissions, industry, photochemical production, dust suspension and sea salt transport. Traffic strongly influenced PM mass and composition. Direct car emissions and road dust resuspension contributed with 44–66% to the fine aerosol and with 12 to 55% to the coarse particles mass at both sites, showing typically highest loads at roadside. In fine particles secondary origin was also quite important in aerosol loading, principally during summer, with 28–48% mass contribution, at R and UB sites respectively. Sea spray has an important contribution of 18–28% to coarse aerosol mass in the studied area, with a highest relative contribution at UB site.Application of Spatial Variability/Mass Balance Analysis permitted the estimation of traffic contribution to soil dust in both size ranges, across sites and seasons, demonstrating that as much as 80% of present dust can result from road traffic resuspension.     

湖北省大气颗粒物浓度时空变化特征

了解大气颗粒物浓度的时空变化格局对于大气污染防治、预警预报等具有重要理论和实践意义。根据2015年1月至2015年12月湖北省13个主要城市53个监测站点每小时发布的PM10和PM2.5浓度数据,研究了湖北省大气颗粒物浓度时空变化特征。结果表明,PM10和PM2.5浓度在空间上均呈现出鄂西部最低、中部最高、东部居中、南北向的均质性;时间上各城市均呈现颗粒物浓度随着月份变化先降低后升高,1月份最高,8月份最低,且呈现夏季浓度<秋季浓度<春季浓度<冬季浓度的变化规律。分析表明,湖北省大气颗粒物浓度时空变化特征与降水量、气温等气象因子呈现出显著负相关关系,与风速关系不显著;与其来源中建筑施工面积、机动车保有量、货运量和客运量、人均GDP和人均第二产值关系紧密。     

Spatial and temporal variations of aerosol sulfate and trace elements in a sourcedominated urban environment

Time-resolved measurements of SO₂, sulfate, particulate carbon and trace metal (Pb, As, K, Mn, Fe and V) concentrations were performed simultaneously at four locations in Ljubljana, Yugoslavia, during February and April of 1985. During the winter three different SO₄²⁻ formation regimes are identified: A—morning period coinciding with maximum emissions and high humidity resulting in maximum SO₄²⁻ concentrations, with the sulfate formation during this period attributed to fast heterogeneous, aqueous oxidation of local SO₂ involving combustion products; B—late evening period with low humidity and high emissions when most SO₄²⁻ is primary; C—the remainder of the day when SO₄²⁻ appears to be of a regional origin and formed by a combination of heterogeneous and homogeneous processes. During the non-heating season, the SO₄²⁻ appears to be of regional origin.     

The composition and sources of PM2.5 organic aerosol in two urban areas of Chile

Fine particle (PM_2.5) samples were collected, using a charcoal diffusion denuder, in two urban areas of Chile, Santiago and Temuco, during the winter and spring season of 1998. Molecular markers of the organic aerosol were determined using GC/MS. Diagnostic ratios and molecular tracers were used to investigate the origin of carbonaceous aerosols. As main sources, road and non-road engine emissions in Santiago, and wood burning in Temuco were identified. Cluster analysis was used to compare the chemical characteristics of carbonaceous aerosols between the two urban environments. Distinct differences between Santiago and Temuco samples were observed. High concentrations of isoprenoid (30–69 ng m⁻³) and unresolved complex mixture (UCM) of hydrocarbons (839–1369 ng m⁻³) were found in Santiago. High concentrations of polynuclear aromatic hydrocarbons (751±304 ng m⁻³) and their oxygenated derivatives (4±2 ng m⁻³), and of n-alk-1-enes (16±13 ng m⁻³) were observed in Temuco.     

Seasonal variation in atmospheric aerosol concentration and composition at urban and rural sites in northern England

Seasonal variations in atmospheric aerosol concentration and composition have been determined at two nearby sites, one urban and one rural, near Leeds, W. Yorkshire. Aerosols, sampled on a daily basis and collected in the size ranges < 2.5 μm and 2.5−15 μm, were analysed for total mass, SO²⁻₄, NO⁻₃, Cl⁻ and NH⁺₄. Dark smoke and SO₂ were also measured at both sites. Results are given covering the period October 1982–September 1983. The average concentration of particles was higher at the urban site. The urban-rural difference in coarse particle concentration, which was about a factor of 2, was more significant than the difference in the fine particle concentration, which was only 1.3. Smoke and SO₂ concentrations showed strong wintertime maxima and summertime minima. Fine NO⁻₃ and Cl⁻ concentrations also had pronounced wintertime maxima and summertime minima attributed to the variation in volatility of their ammonium salts. Total mass, SO²⁻₄ and NH⁺₄ did not show any clear seasonal variations. Anti-cyclonic conditions in summer resulted in elevated mass concentrations of secondary pollutants, e.g. SO²⁻₄. The fine fraction contained ca 50% water-soluble inorganic ions at Leeds and slightly more at the rural site. These proportions showed little seasonal variation.     

Carbonaceous aerosol in urban and rural European atmospheres: estimation of secondary organic carbon concentrations

Aerosol samples from urban, rural and coastal areas in Europe were analysed for carbonaceous content by a thermaloptical transmission method. The fraction of particulate organic carbon with a secondary origin in gas/particle conversion of volatile organic compounds was estimated from the minimum ratio between particulate organic and black carbon, which occurred during periods of reduced photochemical activity. Values calculated by this method ranged from a minimum of 17%, in Birmingham, UK, during winter, to a maximum of 78% at a rural coastal area, in Portugal, with air masses transported directly from the ocean. A clear seasonal dependence was observed at both rural and urban environments, with minimum secondary organic carbon production during winter.     

Role of organic and black carbon in the chemical composition of atmospheric aerosol at European background sites

The mass concentrations of inorganic ions, water-soluble organic carbon, water-insoluble organic carbon and black carbon were determined in atmospheric aerosol collected at three European background sites: (i) the Jungfraujoch, Switzerland (high-alpine, PM_2.5 aerosol); (ii) K-puszta, Hungary (rural, PM_1.0 aerosol); (iii) Mace Head, Ireland (marine, total particulate matter). At the Jungfraujoch and K-puszta the contribution of carbonaceous compounds to the aerosol mass was higher than that of inorganic ions by 33% and 94%, respectively. At these continental sites about 60% of the organic carbon was water soluble, 55–75% of the total carbon proved to be refractory and a considerable portion of the water soluble, refractory organic matter was composed of humic-like substances. At Mace Head the mass concentration of organic matter was found to be about twice than that of nonsea-salt ions, 40% of the organic carbon was water soluble and the amount of highly refractory carbon was low. Humic-like substances were not detected but instead low molecular weight carboxylic acids were responsible for about one-fifth of the water-soluble organic mass. These results imply that the influence of carbonaceous compounds on aerosol properties (e.g. hygroscopic, optical) might be significant.     

大气气溶胶酸度的研究进展

大气气溶胶的环境效应、气候效应和健康效应均与气溶胶的物理化学性质直接相关,其中大气气溶胶酸度是其重要的性质之一。大气气溶胶酸度对酸沉降、灰霾的形成具有重要作用,并影响大气非均相化学反应,相关研究已成为国际研究的热点。对国内外学者近年来在大气气溶胶酸度对大气环境与人体健康的影响、大气气溶胶酸度的影响因素与变化规律、大气气溶胶酸度/酸化缓冲能力的测定与计算方法、大气气溶胶酸性成分采集系统等方面的研究进展作了较系统的综述,并对大气气溶胶酸度研究未来的发展进行了展望。     

BTX in urban areas of eastern Spain: a focus on time variations and sources

Environmental Science and Pollution Research - Seasonal and daily cycles of BTX were studied in a non-industrialized city (Alicante) and an urban area near an oil refinery plant (Castellón) in...     

Variability of atmospheric pesticide concentrations between urban and rural areas during intensive pesticide application

Intensive pesticide use leads to the contamination of water, soil and atmosphere. Atmospheric transport is responsible for pesticide dispersal over long distances. In this study, we evaluate the local dispersal of pesticides from agricultural to urban areas. For this purpose, three high-volume samplers, each equipped with a glass fiber filter and XAD-2 resin for the sampling of particulate and gas phase have been placed in a south-west transect (predominant wind direction) characteristic of rural and urban areas. The urban site (Strasbourg centre) is situated in the middle of two rural sites. Samples were taken simultaneously at three sites during pesticide treatments in autumn and spring 2002–2003. Sampling took place for 24 h at a flow rate of 10–15 m³ h⁻¹. The pesticides studied were those commonly used in the Alsace region for all crops (maize, cereal, vines …). Many of the pesticides analysed in atmospheric samples were not detected or observed very episodically at very low concentrations. For metolachlor, alachlor, trifluralin, atrazine and diflufenican, higher concentrations were observed, essentially during the application of these compounds. Moreover, some “spraying peaks” were observed for alachlor in the south rural site (near crops) at a level of 31 ng m⁻³ on 16–17 May 2003. These results show site and time dependence of atmospheric contamination by pesticides. A limited dispersal was also observed especially in the urban area during the application periods of pesticides.     

Changes in elemental composition and mass of atmospheric aerosol pollution between 1996 and 2002 in a Central European city

Median atmospheric concentrations of Pb, Br, S, As, Se, and particulate matter (PM) decreased, and median concentrations of Sb, Cu, Zn, Fe, Ca, Cr and Ba increased in urban aerosol in downtown Budapest between 1996 and 2002. The changes in Pb and Br concentrations were unambiguously attributed to the phasing out of leaded gasoline. The increments were mainly related to and explained by non-exhaust vehicular emissions. The mechanical wear of asbestos-free brake linings of road vehicles contributed to the concentration of Cu and Sb on average by 69% and 66%, respectively in the PM10 size fraction. Tire rubber abrasion was a major source for atmospheric Zn; on average, non-crustal sources accounted for 67% of Zn in the PM10 size fraction. Contribution of the tire wear component to the PM10 mass was estimated to be 6% at most, while its contribution to organic aerosol was of the order of 15%.     

大气气溶胶中有机成分研究进展

有机物是大气气溶胶的重要组成部分,尤其是在细颗粒中,可占其干重的10%～70%。由于有机气溶胶的健康及气候效应,有机物的组成、源分布、颗粒行为等的研究越来越受到人们的重视。其中,有机物成分的鉴别和定量已成为近年来的研究热点。在分析中,就目前有机气溶胶的采样、有机成分提取、分离及定性、定量分析方法进行了综述,并比较了各种方法的优缺点。     

Assessment of the aerosol water content in urban atmospheric particles by the hygroscopic growth measurements in Sapporo,Japan

Aerosol water content (AWC) of urban atmospheric particles was investigated based on the hygroscopic growth measurements for 100 and 200 nm particles using a hygroscopicity tandem differential mobility analyzer in Sapporo, Japan in July 2006. In most of the humidogram measurements, presence of less and more hygroscopic mode was evident from the different dependence on relative humidity (RH). The volume of liquid water normalized by that of dry particle (V_w(RH)/V_dry) was estimated from the HTDMA data for 100 and 200 nm particles. The RH dependence of V_w(RH)/V_dry was well represented by a fitted curve with a hygroscopicity parameter κ_eff. The κ_eff values for 200 nm particles were in general higher than those for 100 nm particles, indicating a higher hygroscopicity of 200 nm particles. Based on the κ_eff values, the volume mixing ratios of water-soluble inorganic compounds (ammonium sulfate equivalent) were estimated to be on average 31% and 45% for 100 and 200 nm particles, respectively. The diurnal variation of κ_eff, with relatively higher values in the noontime and nighttime and lower values in the morning and evening hours, was observed for both particle sizes. The V_w(RH)/V_dry values under ambient RH conditions were estimated from κ_eff to range from 0.05 to 2.32 and 0.06 to 2.43 for 100 nm and 200 nm particles, respectively. The degree of correlation between κ_eff and V_w(RH)/V_dry at ambient RH suggests a significant contribution of the variation of κ_eff to atmospheric AWC in Sapporo.