Local and non-local sources of airborne particulate pollution at Beijing

A new element tracer technique has firstly been established to estimate the contributions of mineral aerosols from both inside and outside Beijing. The ratio of Mg/Al in aerosol is a feasible element tracer to distinguish between the sources of inside and outside Beijing. Mineral aerosol, inorganic pollution aerosol mainly as sulfate and nitrate, and organic aerosol are the major components of airborne particulates in Beijing, of which mineral aerosol accounted for 32%–-67% of total suspended particles (TSP), 10% –70% of fine particles (PM2.5), and as high as 74% and 90% of TSP and PM_2.5, respectively, in dust storm. The sources from outside Beijing contributed 62% (38%–-86%) of the total mineral aerosols in TSP, 69% (52%–-90%) in PM₁₀, and 76% (59%–-93%) in PM_2.5 in spring, and 69% (52%–-83%), 79% (52%–-93%), and 45% (7% – 79%) in TSP, PM₁₀, and PM_2.5, respectively, in winter, while only ≈20% in summer and autumn. The sources from outside Beijing contributed as high as 97% during dust storm and were the dominant source of airborne particulates in Beijing. The contributions from outside Beijing in spring and winter are higher than those in summer, indicating clearly that it was related to the various meteorological factors.     

塔克拉玛干沙漠黑碳气溶胶的特性及来源

长期监测并采集塔克拉玛干沙漠腹地的大气颗粒物及黑碳气溶胶样品.在塔克拉玛干沙漠腹地,沙尘气溶胶中的黑碳在PM10中的年平均含量高达1.14%,这说明在人迹罕至的塔克拉玛干沙漠地区,其上空的沙尘气溶胶也已经受到人为活动的影响.黑碳气溶胶具有明显的季节变化和日变化,冬季最高,平均达2261.7ngm-3,依次为冬季春季秋季夏季.黑碳气溶胶日变化特征与城市地区恰好相反,夜间高于白天,午夜0:00～2:00出现峰值,而在上午8:00～11:00出现低值.非沙尘暴期间黑碳对PM10的贡献是沙尘暴时期的11倍.塔里木盆地周边绿洲带人为活动,尤其是新疆南北部地区跨越春秋冬三季的居民采暖所产生的黑碳经由局地、区域或长途传输是塔克拉玛干沙漠腹地黑碳气溶胶的主要来源,也是沙漠黑碳气溶胶具有明显的季节特征和日变化的主要原因.随着沙尘气溶胶的长途传输,沙漠每年大约输出6.3×104吨黑碳气溶胶,这势必会对全球的气候与环境变化产生一定影响.     

Evaluation of airborne particles at the Alhambra monument in Granada, Spain

As a part of an ongoing investigation regarding the air quality at the Alhambra monument (UNESCO World Cultural Heritage), indoor and outdoor atmospheric aerosols (PM₁ and PM_10-1) and pollutant gases (O₃, NO₂, SO₂ and NH₃) were studied during summer and winter. Bulk elements, ionic compounds and black carbon (BC) in aerosols were analyzed with X-ray fluorescence spectrometry, ion chromatography and aethalometry/reflectometry, respectively. Natural PM_10-1 aerosols, such as carbonate-rich soil and sea salts, reacted with a typical urban atmosphere, producing a mixture of particulates with diverse chemical composition. The content/formation of secondary inorganic aerosols depended on the air temperature and absolute humidity. Ratios of typical mineral elements (i.e., Ti/Fe and Si/Fe) showed that Saharan dust events contribute to the composition of the observed mineral aerosol content. BC, V and Ni originated from diesel exhaust, while Cu, Cr, Pb and Zn came mainly from non-exhaust vehicular emissions. Weathering phenomena, such as blackening and pigment discoloration, which could arise from gradual aerosol deposition indoors, are discussed.     

Occurrence,evolution and degradation of heavy haze events in Beijing traced by iodine-127 and iodine-129 in aerosols

Heavy haze events have become a serious environment and health problem in China and many developing countries, especially in big cities, like Beijing. However, the factors and processes triggered the formation of secondary particles from the gaseous pollutants are still not clear, and the processes driving evolution and degradation of heavy haze events are not well understood. Iodine isotopes (¹²⁷I and ¹²⁹I) as tracers were analyzed in time series aerosol samples collected from Beijing. It was observed that the ¹²⁷I concentrations in aerosols peaked during the heavy haze events. The conversion of gaseous iodine to particular iodine oxides through photochemical reactions provides primary nuclei in nucleation and formation of secondary air particles, which was strengthened as the external iodine input from the fossil fuel burning in the south/southeast industrial cities and consequentially induced heavy haze events. Anthropogenic ¹²⁹I concentrations peaked during clean air conditions and showed high levels in spring and later autumn compared to that in summer. ¹²⁹I originated from the direct air discharges and re-emissions from contaminated seawaters by the European nuclear fuel reprocessing plants was transported to Beijing by the interaction of Westerlies and East Asian winter monsoon. Three types of mechanisms were found in the formation and evolution of heavy haze events in Beijing by the variation of ¹²⁷I and ¹²⁹I, i.e., iodine oxides intermediated secondary air particles, dust storm and mixed mode by both secondary air particles and dust storm induced processes.     

Seasonal characteristics of biomass burning contribution to Beijing aerosol

Along with the rapid economic growth and urbani-zation, a number of cities in China are facing the problem of severe air pollution with airborne particles (particulate matter) as the major pollutant identified most frequently. Urban airborne particles are…     

INAA study for characterization of PM10 and PM2.5 in Beijing and influence of dust storm

Summary PM₁₀ and PM_2.5 samples were collected simultaneously in Beijing, China, and analyzed by INAA and ICP-MS. Seasonal variations of the concentrations of ambient particles and their elemental compositions were found. The main sources of PM₁₀ and PM_2.5 in spring were the crust, coal burning and vehicle exhaust, in which the former was significant. During a strong dust storm, the concentrations of the crustal elements in PM₁₀ and PM_2.5 increased remarkably, but the concentrations of some anthropogenic elements decreased. The enrichment factors of these anthropogenic elements also decreased sharply during the dust storm, which indicated that they were mostly originated from local anthropogenic pollution and diluted by the huge amount of dust.     

A new approach for the determination of sulphur in airborne particles by HR-CS ETAAS

In this work, water and nitric acid extractable sulphur concentrations in PM2.5 fraction of urban aerosols were determined by high-resolution continuum source electrothermal molecular absorption spectrometry using most suitable CS molecular absorption band at 258.056 nm. For this purpose, the PM2.5 airborne particulates were collected on quartz filters using a high-volume sampler (500 L/min) in Istanbul (Turkey) during six months (January–June) of two consecutive years. The instrumental and experimental parameters (pyrolysis temperature, molecule formation temperature and leaching reagents) were optimised. The validity of the method for the sulphur was tested using standard reference material and the results were found to be in the uncertainty limits of the certified value.     

Chemical characterization of particulate matter suspended in the atmosphere by energy dispersive X-ray fluorescence (EDXRF)

Summary This paper presents the first measurement of the elemental composition of the suspended particulate matter in the atmosphere of Londrina city (Paraná State, Brazil). The sampling was accomplished in the summer of 2003 and in the winter of 2002, with a stacker filter holder, collecting simultaneously the fine particulates (PM_2.5) and the coarse particulates (PM₁₀). The concentration of K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br and Pb associated with particulate matter was determined by energy dispersive X-ray fluorescence. The results of the grouping analysis suggested that the elements in the aerosol particles came from two sources: soil re-suspension and industrial or anthropogenic activities.     

Absorption and scattering characterization of airborne microparticulates by a cavity ringdown technique

Nonresonant cavity ringdown laser absorption spectroscopy (CRLAS) was applied for detection and characterization of airborne particulates. Sensitive detection of a variety of aerosols under ambient conditions was achieved. The method provides, for the first time, time-resolved absolute aerosol concentration, with spatial resolution (along a line). The first report on absorption spectroscopy of monodispersed aerosols (in the size range 100–200 nm) is provided, and comparisons are made with the bulk data. The results indicate the possibility of applying CRLAS for selective analysis of aerosols. A new method for estimating the aerosol refraction index is also obtained from the ringdown data.     

Physicochemical properties of nitrate aerosols: implications for the atmosphere

As aerosols, such as sea salt and mineral dust, are transported through the atmosphere they undergo heterogeneous reactions with nitrogen oxides to form nitrate salts. The nitrate salt can have quite different physicochemical properties than the original aerosol, resulting in an aerosol that will markedly differ in its climate impact, heterogeneous chemistry, and photoactivity. In this Feature Article, we will review some aspects of the importance of aqueous nitrate aerosols as well as describe a new multi-analysis aerosol reactor system (MAARS) that is used to measure the physicochemical properties of these atmospherically relevant aerosols. Here we show measurements of the hygroscopic properties, cloud condensation nuclei activity, and FTIR extinction of nitrate salt aerosol. In particular, we have measured the hygroscopic growth of 100 nm size-selected nitrate particles including NaNO3, Ca(NO3)2, Mg(NO3)2, and a 1:1 mixture of Ca(NO3)2 and Mg(NO3)2 as a function of relative humidity (RH) at 298 K. Using K?hler theory, we have quantified the water content of these particles with increasing RH. FTIR extinction measurements of the full size distribution of each of the nitrate aerosols are analyzed to yield information about the local solvation environment of the nitrate ions and the long-wavelength light scattering of the particles at different RH. Furthermore, we have measured and compared the cloud condensation nuclei (CCN) activity of CaCO3, a large component of mineral dust aerosol, and Ca(NO3)2, a product of atmospherically aged CaCO3 through reaction with nitrogen oxides, at supersaturations from 0.1% to 0.9%. These quantitative physicochemical data are needed if we are to better understand the chemistry as well as the climate effects of atmospheric aerosols as they are entrained, transported, reacted, and aged in the atmosphere. Our studies here focus on aqueous nitrate salts, the products of the reaction of nitrogen oxides with sea salt and mineral dust aerosol.     

Evidence of coal combustion contribution to ambient VOCs during winter in Beijing

Volatile organic compounds(VOCs)play an important role in ozone and secondary organic aerosol(SOA)formation,but VOCs sources during winter are not fully understood.To investigate VOCs sources during winter,mixing ratios of C2–C12 VOCs were measured at an urban site in Beijing from December 29,2011to January 17,2012.Correlation analysis of toluene to benzene and i-pentane to n-pentane suggest that coal combustion could also be an important source for VOCs besides vehicular emissions.Source apportionment results show that coal combustion and vehicular emissions contributed 28%–39%and31%–45%to ambient VOCs during winter,respectively.Backward trajectory analyses demonstrated that contributions from the burning of coal were higher when air masses came from southern regions outside Beijing.Close attention should be paid to VOCs emissions from coal combustion in Beijing city and the vicinity to the South.     

Chemical fractionation of elements in airborne particulate matter: primary results on PM10 and PM2.5 samples in the Lazio region (central Italy)

This paper describes how a two-step chemical fractionation method that allows the determination of 17 elements in airborne particulate matter, has been applied to a monitoring campaign of PM10 and PM2.5 in the Lazio region (Italy). This method involved an extraction in a pH buffered aqueous solution followed by a microwave-assisted acid digestion of the residue. With respect to the determination of the total elemental contents, the evaluation of a soluble fraction provides more reliable information on the presence and of the destiny of heavy metals in the environment. Furthermore, the pH buffered extraction conditions chosen, rendered the results independent of the intrinsic acidity of the collected samples and, although the chemical fractionation has a purely operational function, it facilitates the study of the relationship between the distribution of solubility and the different emission sources. Results are discussed in relation to the different concentration and the different degrees of solubility of the elements observed in two sampling sites; one in an urban and one in a rural environment. Since in-parallel sampling of PM2.5 and PM10 were performed in both sites, the influence of particle size is also discussed. Behaviour of some tracers deriving from both vehicular traffic, with particular attention to re-suspended road dusts, and naturally generated particulate matter, such as marine aerosol and Saharian dust, are discussed.     

ToF-SIMS analysis of chemical composition of atmospheric aerosols in Beijing

Atmospheric aerosols collected from each season in urban Beijing have been studied using time-of-flight secondary ion mass spectrometry (ToF-SIMS). The chemical composition of atmospheric aerosol particles during various atmospheric pollution levels was analyzed and distinguished by principal component analysis (PCA). The differences and sources of the components of the aerosol particles were explored. The results showed that the fine particulate matter from heavily polluted days mainly consists of inorganic salts and organic compounds, such as hydrocarbons, nitrogen- or sulfur-containing hydrocarbons, and their oxides. Samples collected from clean days in the four seasons were also analyzed. Only the samples collected in spring showed a significant difference from the other three seasons. We concluded that the main source of pollution in the Beijing urban area was fossil fuel combustion from motor vehicles.     

INAA of Aerosol Samples in Mexico City

Total solid particles (TSP), respirable particles (RP) PM10 and 17 metallic pollutants were measured in dwellings in the Metropolitan Zone of Mexico Valley (MZMV) by gravimetry and instrumental neutron activation analysis (INAA). Monitoring was performed in Northeast, Center, Southeast and Southwest Zones in the winter and spring seasons. In general, the average concentration of contaminants (derived from industrial activities) that we have determined have increased with time. TSP and RP PM10 are often above the US and Mexican norms.     

广州市夏、冬季室内外PM2.5中元素组分的特征与来源

通过采集广州市9个居民住宅室内、外的PM2.5样品,测定分析PM2.5中18个元素组分的质量浓度,分析讨论其污染、分布特征并解析其污染来源。经过比较得知,广州市PM2.5中元素污染较严重;不同类型住宅PM2.5中元素浓度存在空间分布特征;大部分元素浓度具有夏季比冬季低的变化特征;室内与室外元素浓度比值介于0.4974～2.0497之间;元素浓度的室内、室外相关拟合结果说明冬季室内空气受室外空气影响比夏季时情况更明显;基于富集因子分析,Se、As、S、Pb、Br、Zn和Cl元素高度富集;Ni、V、Cu元素中等富集,主要来自人为源,而Cr、Sr、K、Mn、Ca和Ti元素不富集,主要来自自然源。     

Novel aerosol detection platform for SARS‑CoV‑2: Based on specific magnetic nanoparticles adsorption sampling and digital droplet PCR detection

The SARS?CoV?2 virus is released from an infectious source (such as a sick person) and adsorbed on aerosols, which can form pathogenic microorganism aerosols, which can affect human health through airborne transmission. Efficient sampling and accurate detection of microorganisms in aerosols are the premise and basis for studying their properties and evaluating their hazard. In this study, we built a set of sub-micron aerosol detection platform, and carried out a simulation experiment on the SARS?CoV?2 aerosol in the air by wet-wall cyclone combined with immunomagnetic nanoparticle adsorption sampling and ddPCR. The feasibility of the system in aerosol detection was verified, and the influencing factors in the detection process were experimentally tested. As a result, the sampling efficiency was 29.77%, and extraction efficiency was 98.57%. The minimum detection limit per unit volume of aerosols was 250 copies (10² copies/mL, concentration factor 2.5).     

Screening of urban aerosol particulate composites for selected metal distribution and their dependence on meteorological parameters

Local atmospheric aerosol particulate samples, collected as composites on daily 6-12 hour basis, at Quaid-i-Azam University campus, Islamabad, Pakistan, using high volume sampling technique, were analysed for Pb, Na, K, Fe, Mn, Cd, Cr, Ni, Zn and Co by FAAS method. The monitoring period ran from October, 2001 through March, 2002, with a total of 105 samples collected on cellulose filters, treated in part with the HNO3-based wet digestion method for metal quantification, and for particle size distribution separately. The metal content of the aerosols was examined in relation to dependence on meteorological parameters, such as temperature, relative humidity, wind speed, sun shine and pan evaporation. Statistical correlation analysis was conducted for multiple metal pairs in aerosols, and the data were examined in relation to meteorological parameters and relevant aerosol particle size fractions. The study revealed no viable strong correlation between the meteorological parameters and metal levels; in general, however, a significant positive correlation was found for temperature. A strong positive correlation was observed for PM<25 and PM2.5-10. For coarse particles (PM10-100 and PM>100), however, a negative correlation was observed. The levels of Na, K, Fe and Zn were found in the range of 1-5 microg/m3 while those for the rest of the metals in the sub microg/m3 range. Principal component analysis and cluster analysis were performed on dataset for source identification and appointment. Largest contribution (33%) was shown by the industrial emissions followed by traffic/road dust (16.7%).     

A seasonal study of atmospheric conditions influenced by the intensive tourist flow in the Royal Museum of Wawel Castle in Cracow, Poland

Increasing mass tourism can generate important microclimatic perturbations and also elevate indoor pollution by the transport of fine particulate matter. The purpose of this research was to study the indoor air conditions in the Royal Museum of Wawel Castle in Cracow, Poland, displaying amongst other valuable works of art also a unique collection of Flemish tapestries. The investigation involved in the determination of transport and deposition of particulate matter brought in by visitors. The microclimate inside the exhibition rooms was also monitored. Samples of suspended particulates were collected inside and outside the museum in winter and summer 2006. On days with intensive tourist visits the concentration of total suspended particulates was significantly higher (i.e., 130 µg/m³ in winter and 49 µg/m³ in summer) than on those days without tourists (i.e., 73 µg/m³ and 22 µg/m³ in winter and summer, respectively). The concentrations of all investigated elements were also considerably higher during the tourist flow. This was especially valid for soil dust associated elements (Si, K, Ca, Al, and Ti), with considerably higher levels in summer than winter. This could be linked with much more frequent tourist activity in the summer period. Also, the concentration of Cl was much higher in winter than summer, due to the use of de-icing salts on the roads and pavements.     

A seasonal study of atmospheric conditions influenced by the intensive tourist flow in the Royal Museum of Wawel Castle in Cracow,Poland

Increasing mass tourism can generate important microclimatic perturbations and also elevate indoor pollution by the transport of fine particulate matter. The purpose of this research was to study the indoor air conditions in the Royal Museum of Wawel Castle in Cracow, Poland, displaying amongst other valuable works of art also a unique collection of Flemish tapestries. The investigation involved in the determination of transport and deposition of particulate matter brought in by visitors. The microclimate inside the exhibition rooms was also monitored. Samples of suspended particulates were collected inside and outside the museum in winter and summer 2006. On days with intensive tourist visits the concentration of total suspended particulates was significantly higher (i.e., 130 µg/m³ in winter and 49 µg/m³ in summer) than on those days without tourists (i.e., 73 µg/m³ and 22 µg/m³ in winter and summer, respectively). The concentrations of all investigated elements were also considerably higher during the tourist flow. This was especially valid for soil dust associated elements (Si, K, Ca, Al, and Ti), with considerably higher levels in summer than winter. This could be linked with much more frequent tourist activity in the summer period. Also, the concentration of Cl was much higher in winter than summer, due to the use of de-icing salts on the roads and pavements.     

Characterizing air particulate matter composition and sources in Lisbon,Portugal

The goal of this research is to determine trends and sources of airborne particulates in the centre of Lisbon, by using speciated particulate-matter data and back-trajectory analyses. Results showed that, in 2007, the annual PM_2.5 concentration exceeded the World Health Organization recommended levels. PM_2.5 diurnal variability and the ratio between weekdays’ and weekends’ concentrations indicated that traffic contributed highly to decreasing air quality. Air back-trajectory analysis showed that maritime air mass transport had a significant role on air quality in Lisbon, promoting the decrease of anthropogenic aerosol concentrations.