Numerical simulations of the effect of building configurations and wind direction on fine particulate matters dispersion in a street canyon

To explore the effect of traffic emissions on air quality within street canyon, the wind flow and pollutant dispersion distribution in urban street canyons of different H/W, building gap and wind direction are studied and discussed by 3D computational fluid dynamics simulations. The largest PM_2.5 concentrations are 46.4, 37.5, 28.4 µg/m³ when x = ? 88, ? 19.3, ? 19.3 m in 1.5 m above the ground level and the ratio of H/W is 1:1, 1:2 and 2:1, respectively. The flow around the top of the building and clearance flow between the buildings in street canyon influence by different H/W, which affected the diffusion of fine particulate matters. The largest PM_2.5 concentrations are 88.1, 31.6 and 33.7 µg/m³ when x = 148.0, ? 92.3 and ? 186.7 m above the ground level of 1.5 m height and the building gap of 0, 20 and 40%, respectively. The air flows are cut by the clearance in the street canyons, and present the segmental characteristics. The largest PM_2.5 concentrations are 10.6, 11.2 and 16.0 µg/m³ when x = 165.3 m, x = 58.0 and 1.5 m above the ground level of 1.5 m height and wind direction of the parallel to the street, perpendicular to the street and southwest, respectively. Modelled PM_2.5 concentrations are basic agreement with measured PM_2.5 concentrations for southwest wind direction. These results can help analyze the difussion of PM_2.5 concentration in street canyons and urban planning.

     

Exposure assessment,chemical characterization and source identification of PM2.5 for school children and industrial downwind residents in Guangzhou,China

To assess the exposure doses of PM_2.5 and to investigate its chemical components for the subpopulation (i.e., school children and industrial downwind residents), simultaneous sampling of indoor and outdoor PM_2.5 was conducted at an elementary school close to traffic arteries and a residence located in the downwind area of a steel plant in metropolitan Guangzhou in 2010. Chemical components, i.e., organic carbon, elemental carbon and 6 water soluble ions were analyzed in PM_2.5. A survey was also conducted to investigate the time-activity patterns of the school children and the industrial downwind residents. Indoor and outdoor PM_2.5 were 63.2 ± 20.1 and (76.7 ± 35.8) μg/m³ at the school, and 118.8 ± 44.7 and 125.7 ± 57.1 μg/m³ in the community, respectively. Indoor PM_2.5 was found to be highly related to outdoor sources, and stationary sources were the significant contributors to PM_2.5 at both sites. The daily average doses of PM_2.5 for the school children at the school (D _children) and the industrial downwind residents in the community (D _residents) were (7.6 ± 1.9) and (36.1 ± 36.8) μg/kg-day, respectively. The daily average doses of particulate organic mass and SO₄ ^2? were the two most abundant chemical components in PM_2.5. PM_2.5 exposure for the school children was contributed by indoor and outdoor environments by 48.8 and 51.2 %, respectively; for the industrial downwind residents, the contributions were 66.0 and 34.0 %, respectively. Age and body weight were significantly and negatively correlated with D _children, while age, body weight and education level were significantly and negatively correlated with D _residents; gender was not a significant factor at both cases.     

Metal characterization of airborne particulate matters in a coastal region

The concentrations of suspended particulate matter in the air of the Orissa Sand Complex had an average value of 128 ± 10 µg m^?3 in residential areas and 170 ± 8 µg m^?3 in mining areas. PM₁₀ levels in residential areas were found to have an average of 35 ± 10 µg m^?3, in mining areas 45 ± 10 µg m^?3. The distribution of some elements is also discussed here. Inhalation doses were observed to be higher in summer than in winter and the rainy season. The highest dose rate was for the age group of 1 year, and health risks were found to be highest for the same. For adults, inhalation dose and health risk are 1.3 times higher in mining than in residential areas.     

Characteristics of PM<Subscript>2.5</Subscript>, CO<Subscript>2</Subscript> and particle-number concentration in mass transit railway carriages in Hong Kong

Fine particulate matter (PM_2.5) levels, carbon dioxide (CO₂) levels and particle-number concentrations (PNC) were monitored in train carriages on seven routes of the mass transit railway in Hong Kong between March and May 2014, using real-time monitoring instruments. The 8-h average PM_2.5 levels in carriages on the seven routes ranged from 24.1 to 49.8 µg/m³, higher than levels in Finland and similar to those in New York, and in most cases exceeding the standard set by the World Health Organisation (25 µg/m³). The CO₂ concentration ranged from 714 to 1801 ppm on four of the routes, generally exceeding indoor air quality guidelines (1000 ppm over 8 h) and reaching levels as high as those in Beijing. PNC ranged from 1506 to 11,570 particles/cm³, lower than readings in Sydney and higher than readings in Taipei. Correlation analysis indicated that the number of passengers in a given carriage did not affect the PM_2.5 concentration or PNC in the carriage. However, a significant positive correlation (p < 0.001, R ² = 0.834) was observed between passenger numbers and CO₂ levels, with each passenger contributing approximately 7.7–9.8 ppm of CO₂. The real-time measurements of PM_2.5 and PNC varied considerably, rising when carriage doors opened on arrival at a station and when passengers inside the carriage were more active. This suggests that air pollutants outside the train and passenger movements may contribute to PM_2.5 levels and PNC. Assessment of the risk associated with PM_2.5 exposure revealed that children are most severely affected by PM_2.5 pollution, followed in order by juveniles, adults and the elderly. In addition, females were found to be more vulnerable to PM_2.5 pollution than males (p < 0.001), and different subway lines were associated with different levels of risk.     

Characteristics of chemical components in PM<Subscript>2.5</Subscript> at a plateau city,South-west China

A sampling campaign including summer, autumn and winter of 2014 and spring of 2015 was accomplished to obtain the characteristic of chemical components in PM_2.5 at three sites of Kunming, a plateau city in South-west China. Nine kinds of water-soluble inorganic ions (WSI), organic and element carbon (OC and EC) in PM_2.5 were analyzed by ion chromatography and thermal optical reflectance method, respectively. Results showed that the average concentrations of total WSI, OC and EC were 22.85±10.95 µg·m^-3, 17.83±9.57 µg·m^-3 and 5.11±4.29 µg·m^-3, respectively. They totally accounted for 53.0% of PM_2.5. Secondary organic and inorganic aerosols (SOA and SIA) were also assessed by the minimum ratio of OC/EC, nitrogen and sulfur oxidation ratios. The annual average concentrations of SOA and SIA totally accounted for 28.3% of the PM_2.5 concentration. The low proportion suggested the primary emission was the main source of PM_2.5 in Kunming. However, secondary pollution in the plateau city should also not be ignorable, due to the appropriate temperature and strong solar radiation, which can promote the atmospheric photochemical reactions.

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PM<Subscript>2.5</Subscript> particulates and metallic elements (Ni,Cu, Zn,Cd and Pb) study in a mixed area of summer season in Shalu,Taiwan

PM_2.5 has become an important environmental issue in Taiwan during the past few years. Moreover, electricity increased significantly during the summertime and TTPP generated by coal burning base is the main electricity provider in central Taiwan. Therefore, summer season has become the main research target in this study. The ambient air concentrations of particulate matter PM_2.5 and PM₁₀ collected by using VAPS at a mixed characteristic sampling site were studied in central Taiwan. The results indicated that the average daytime PM_2.5 and PM₁₀ particulate concentrations were occurred in May and they were 44.75 and 57.77 µg/m³ in this study. The results also indicated that the average nighttime PM_2.5 and PM₁₀ particulate concentrations were occurred in June and they were 38.19 and 45.79 µg/m³ in this study. The average PM_2.5/PM₁₀ ratios were 0.7 for daytime, nighttime and 24-h sampling periods in the summer for this study. This value was ranked as the lowest ratios when compared to the other seasons in previous study. Noteworthy, the results further indicated that the metallic element Pb has the mean highest concentrations for 24-h, daytime and nighttime sampling periods when compared to those of the other metallic elements (Ni, Cu, Zn and Cd). The average mean highest metallic Pb concentrations in PM10 were 110.7, 203.0 and 207.2 ng/m³ for 24-h, daytime and nighttime sampling periods in this study. And there were 59.53, 105.2 and 106.6 ng/m³ for Pb in PM2.5 for 24-h, daytime and nighttime sampling periods, respectively. Moreover, the results further indicated that mean metallic element Pb concentrations on PM_2.5 and PM₁₀ were all higher than those of the other elements for 24 h, day and nighttime.     

High seasonal variation of atmospheric C and particle concentrations in Delhi,India

The highly populated Indian regions are currently in a phase of rapid economic growth resulting in high emissions of carbonaceous aerosols. This leads to poor air quality and impact on climate. The chemical composition of carbonaceous aerosols has rarely been studied in industrial areas of India. Here, we investigated carbonaceous aerosols in particulate matter (PM) monthly in the industrial area of Delhi in 2011. The concentrations of organic C and elemental C in PM₁₀ fraction were analyzed. Results show a clear seasonal variability of organic and elemental C. PM₁₀ ranged 95.9–453.5 μg m^?3, organic C ranged 28.8–159.4 μg m^?3, and elemental C ranged 7.5–44.0 μg m^?3; those values were higher than reported values. Organic and elemental C were correlated with each other in pre-monsoon and winter seasons, implying the existence of similar emission sources such as coal combustion, biomass burning and vehicular exhaust. The annual average contribution of total carbonaceous aerosols in PM₁₀ was estimated as 62 %.     

Airborne fine particulate matter (PM2.5) at industrial,high- and low-density residential sites in a Nigerian megacity

Abstract

Airborne particulate matter PM_2.5 was collected in an industrial, a low-density, and a high-density residential area of Lagos from December 2010 to November 2011, and elemental composition was determined by proton-induced X-ray emission. Across the months, mass concentrations ranged from 13 to 237?µg?m^?3, exceeding the World Health Organization guideline value of 10?µg?m^?3. Data on 24 elements were obtained, with maximum values during Harmattan season months; source identification and apportionment studies by positive matrix factorization suggested that petroleum oil combustion (70%) was the major source of PM_2.5 and could pose a great hazard to Lagos receptors.     

Outdoor air particle-bound trace metals in four selected communities in Ibadan,Nigeria

Trace metal concentrations were determined in particulate matter (PM₁₀) in ambient air of four purposively selected residential areas in Ibadan, Nigeria namely Bodija market (BM), Ojo Park (OP), Oluyole Estate (OE) and University of Ibadan (UI). PM₁₀ was determined in the morning (7–10 a.m.) and afternoon (2–5 p.m.) for 12 weeks in the dry season months of January–March using a volumetric sampler following standard procedures and levels compared with WHO guideline limits. Glass-fibre filter papers exposed to the particulate matter were digested using appropriate acid mixtures, and the digest analysed for trace metals including Ni, Cr, Mn, Zn, and Pb using ICPMS method and levels compared with WHO limits. Data was analysed using ANOVA and Pearson correlation test at 5 % level of significance. The highest mean PM₁₀ concentrations 502.3 ± 39.9 μg/m³ were recorded in the afternoon period at BM, while the lowest concentration 220.6 ± 69.9 μg/m³ was observed in the morning hours at UI. There was a significant difference between the PM₁₀ levels across the various locations (p < 0.05), and all the levels were higher than WHO limit of 50 μg/m³. The highest levels of Ni, Zn and Pb were recorded at BM, which also had the highest PM₁₀ burden. The trend in Pb levels across the locations was BM > UI > OP > OE with the highest level 5.70 μg/m³ in BM nearly fourfolds WHO limits of 1.5 μg/m³. There was a significant correlation between PM₁₀ and Ni (p < 0.05).Urban communities with increased human activities especially motor traffic recorded both higher levels of PM₁₀ and toxic trace metals. There is need to carry out source apportionment to establish the origin of these trace metals in future studies.     

Metals and metalloids in PM10 in Nandan County,Guangxi, China,and the health risks posed

Intense mining, smelting, and tailing activities of polymetallic ore deposits have affected the environment in Nandan County, Guangxi, China. Samples of particulates with aerodynamic diameters low or equal 10 μm (PM₁₀) were collected in Nandan County to investigate the concentrations of and health risks posed by 17 metals and metalloids in the PM₁₀. The metal and metalloid concentrations were lower than those found in other industrial cities. The mean Cr concentration was 7.48 ng/m³. Significant higher metal and metalloid concentrations were found in PM₁₀ from mining areas (Dachang and Chehe) than from the control area (Liuzhai) (p < 0.05). Principal component analysis indicated that the main sources of Ba, Co, Cr, Fe, K, Mg, Mo, Na, and Sr were resuspension of the soil produced through mineral erosion, the main sources of As, Cd, Cu, Pb, Sb, and Zn were smelting and mining activities, and the main source of Ni was fossil fuel combustion. Higher non-carcinogenic and carcinogenic risks were posed in Dachang and Chehe than in Liuzhai. The non-carcinogenic risks posed to adults and children by individual metals and metalloids in PM₁₀ at all the sites were low, but the non-carcinogenic risks posed to children by all the metals and metalloids together exceeded the safe level (i.e., risk value > 1). The carcinogenic risks posed by Cd, Ni, and Pb were negligible at all sites, while As, Co, and Cr posed potential carcinogenic risks to the residents.

     

Oxidative potential (OP) and mineralogy of iron ore particulate matter at the Gol-E-Gohar Mining and Industrial Facility (Iran)

Concentrations of total suspended particulate matter, particulate matter with aerodynamic diameter <2.5 μm (PM_2.5), particulate matter <10 μm (PM₁₀), and fallout dust were measured at the Iranian Gol-E-Gohar Mining and Industrial Facility. Samples were characterized in terms of mineralogy, morphology, and oxidative potential. Results show that indoor samples exceeded the 24-h PM_2.5 and PM₁₀ mass concentration limits (35 and 150 µg m^?3, respectively) set by the US National Ambient Air Quality Standards. Calcite, magnetite, tremolite, pyrite, talc, and clay minerals such as kaolinite, vermiculite, and illite are the major phases of the iron ore PM. Accessory minerals are quartz, dolomite, hematite, actinolite, biotite, albite, nimite, laumontite, diopside, and muscovite. The scanning electron microscope structure of fibrous-elongated minerals revealed individual fibers in the range of 1.5 nm to 71.65 µm in length and 0.2 nm to 3.7 µm in diameter. The presence of minerals related to respiratory diseases, such as talc, crystalline silica, and needle-shaped minerals like amphibole asbestos (tremolite and actinolite), strongly suggests the need for detailed health-based studies in the region. The particulate samples show low to medium oxidative potential per unit of mass, in relation to an urban road side control, being more reactive with ascorbate than with glutathione or urate. However, the PM oxidative potential per volume of air is exceptionally high, confirming that the workers are exposed to a considerable oxidative environment. PM released by iron ore mining and processing activities should be considered a potential health risk to the mine workers and nearby employees, and strategies to combat the issue are suggested.     

Air quality and PM10-associated poly-aromatic hydrocarbons around the railway traffic area: statistical and air mass trajectory approaches

Diesel engine railway traffic causes atmosphere pollution due to the exhaust emission which may be harmful to the passengers as well as workers. In this study, the air quality and PM₁₀ concentrations were evaluated around a railway station in Northeast India where trains are operated with diesel engines. The gaseous pollutant (e.g. SO₂, NO₂, and NH₃) was collected and measured by using ultraviolet–visible spectroscopy. The advanced level characterizations of the PM10 samples were carried out by using ion chromatography, Fourier-transform infrared, X-ray diffraction, inductively coupled plasma optical emission spectrometry , X-ray photoelectron spectroscopy, field-emission scanning electron microscopy with energy-dispersive spectroscopy, and high-resolution transmission electron microscopy with energy-dispersive spectroscopy techniques to know their possible environmental contaminants. High-performance liquid chromatography technique was used to determine the concentration of polycyclic aromatic hydrocarbons to estimate the possible atmospheric pollution level caused by the rail traffic in the enclosure. The average PM₁₀ concentration was found to be 262.11 µg m⁻³ (maximum 24 hour) which indicates poor air quality (AQI category) around the rail traffic. The statistical and air mass trajectory analysis was also done to know their mutual correlation and source apportionment. This study will modify traditional studies where only models are used to simulate the origins.

     

Health risk of aerosols and toxic metals from incense and joss paper burning

We report for the first time the distribution and hazard potential of aerosol and metals resulting from joss paper burning. Burning joss paper and incense is a traditional custom in many Oriental countries. Large amounts of air pollutants, including particles, polycyclic aromatic hydrocarbons, toxic metals and other gaseous pollutants, are released into the environment during the burning stage. Many investigations have reported on the emission of pollutants from the incense burning. However, no work has been reported until now on the analysis of the released pollutants apart from polycyclic aromatic hydrocarbons. In this study, a micro-orifice uniform-deposit impactor and inductively coupled plasma optical emission spectrometry were, respectively, used to collect aerosols and characterize the toxic metals from joss paper burning. We studied two types of particulate matter (PM): PM_2.5 that are particles with a diameter smaller than 2.5 μm and PM₁₀ that are particles with a diameter smaller than 10 μm. PM_2.5 are the most potentially toxic particles. Our results showed that PM_2.5 are the major component of the pollutants and that the PM_2.5 to PM₁₀ ratio ranged from 62 to 99%. The metals Na, Ca, Mg, Al and K were the main species in the aerosol and in the bottom ash.     

The impact of artisanal gold mining,ore processing and mineralization on water quality in Marmato,Colombia

Marmato, Colombia, has been an important centre of gold mining since before the first Spanish colonizers arrived in 1536. The Marmato deposit is hosted in a dacite and andesite porphyry stock as sheeted sulphide-rich veinlet systems. The district is currently experiencing a surge in both major mining projects and artisanal mining, driven by sustained high gold prices. Ore from small-scale and artisanal gold mining is processed in numerous small mills (entables) around Marmato, which impact surface water quality through the discharge of milled waste rock slurry, highly alkaline cyanide-treated effluent, and high dissolved metal loads. To investigate the impact of artisanal mining and ore processing, water samples were collected in January 2012 from streams around Marmato. The average dissolved metal concentrations in impacted streams were Zn, 78 mg L^?1; Pb, 0.43 mg L^?1; Cu, 403 µg L^?1 Cd, 255 µg L^?1; As, 235 µg L^?1; Ni, 67 µg L^?1; Co, 55 µg L^?1; Sb, 7 µg L^?1; and Hg, 42 ng L^?1, exceeding World Health Organization drinking water guidelines. In addition, arsenic speciation was conducted in-situ and indicated that 91–95% of inorganic arsenic species is in the form of As(V). Spatial analysis of the data suggests that entables processing ore for artisanal miners are the main contributor to water pollution, with high sediment loads, alkalinity and elevated concentrations of dissolved arsenic, cadmium, mercury and lead, caused by the processing of gold-bearing sulphides in the entables. Geochemical data from surface water were compared to a comprehensive data set of whole rock analyses from drill core and channel samples from the deposit, indicating that the deposit is significantly enriched in gold, silver, lead, zinc, arsenic, antimony, and cadmium compared to crustal averages, which is reflected in the surface water geochemistry. However, elevated mercury levels in surface water cannot be explained by enrichment of mercury in the deposit and strongly suggest that mercury is being added to concentrates during ore processing to amalgamate fine gold.

     

Evaluation of the levels and sources of trace elements in urban particulate matter

An assessment of air quality of Belgrade, Serbia, was performed by determining the trace element content in airborne daily PM₁₀ and PM_2.5 samples collected from a central urban area. The ambient concentrations of Zn were the highest in PM_2.5 (1,998.0 ng m⁻³). Multivariate receptor modelling (principal component analysis and cluster analysis) has been applied to determine the contribution of different sources of specific metallic components in airborne particles. The obtained results showed that vehicle traffic and fossil fuel combustion in stationary objects were the main sources of trace metals in Belgrade urban aerosols.     

Trace element concentration in fine particulate matter (PM<Subscript>2.5</Subscript>) and their bioavailability in different microenvironments in Agra,India: a case study

Exposure to airborne particulate matter results in the deposition of millions of particle in the lung; consequently, there is need for monitoring them particularly in indoor environments. Case study was conducted in three different microenvironments, i.e., urban, rural and roadside to examine the elemental bioavailability in fine particulate matter and its potential health risk. The samples were collected on polytetrafluoroethylene filter paper with the help of fine particulate sampler during August–September, 2012. The average mass concentration of PM_2.5 was 71.23 µg m^?3 (rural), 45.33 µg m^?3 (urban) and 36.71 µg m^?3 (roadside). Elements in PM_2.5 were analyzed by inductively coupled plasma atomic emission spectroscopy. Percentage bioavailability was determined to know the amount of soluble fraction that is actually taken across the cell membrane through inhalation pathway. Cadmium and lead were found to have cancer risk in a risk evaluation using an Integrated Risk Information system.     

Acute associations between air pollution on premature rupture of membranes in Hefei,China

Numerous studies had focused on the association between air pollution and health outcomes in recent years. However, little evidence is available on associations between air pollutants and premature rupture of membranes (PROM). Therefore, we performed time-series analysis to evaluate the association between PROM and air pollution. The daily average concentrations of PM_2.5, SO₂ and NO₂ were 54.58 μg/m³, 13.06 μg/m³ and 46.09 μg/m³, respectively, and daily maximum 8-h average O₃ concentration was 95.67 μg/m³. The strongest effects of SO₂, NO₂ and O₃ were found in lag4, lag06 and lag09, and an increase of 10 μg/m³ in SO₂, NO₂ and O₃ was corresponding to increase in incidence of PROM of 8.74% (95% CI 2.12–15.79%), 3.09% (95% CI 0.64–5.59%) and 1.68% (95% CI 0.28–3.09%), respectively. There were no significant effects of PM_2.5 on PROM. Season-specific analyses found that the effects of PM_2.5, SO₂ and O₃ on PROM were more obvious in cold season, but the statistically significant effect of NO₂ was observed in warm season. We also found the modifying effects by maternal age on PROM, and we found that the effects of SO₂ and NO₂ on PROM were higher among younger mothers (<?35 years) than advanced age mothers (≥?35 years); however,?≥?35 years group were more vulnerable to O₃ than?<?35 years group. This study indicates that air pollution exposure is an important risk factor for PROM and we wish this study could provide evidence to local government to take rigid approaches to control emissions of air pollutants.

     

Water-soluble inorganic ions in airborne particulates from the nano to coarse mode: a case study of aerosol episodes in southern region of Taiwan

In 2004, airborne particulate matter (PM) was collected for several aerosol episodes occurring in the southern region of Taiwan. The particulate samples were taken using both a MOUDI (Micro-orifice Uniform Deposit Impactor) and a nano-MOUDI sampler. These particulate samples were analyzed for major water-soluble ionic species with an emphasis to characterize the mass concentrations and distributions of these ions in the ambient ultrafine (PM_0.1, diameter <0.1 μm) and nano mode (PM_nano, diameter <0.056 μm) particles. Particles collected at the sampling site (the Da-Liao station) on the whole exhibited a typical tri-modal size distribution on mass concentration. The mass concentration ratios of PM_nano/PM_2.5, PM_0.1/PM_2.5, and PM₁/PM_2.5 on average were 1.8, 2.9, and 71.0%, respectively. The peak mass concentration appeared in the submicron particle mode (0.1 μm < diameter <1.0 μm). Mass fractions (percentages) of the three major water-soluble ions (nitrate, sulfate, and ammonium) as a group in PM_nano, PM_0.1, PM₁, and PM_2.5 were 18.4, 21.7, 50.0, and 50.7%, respectively. Overall, results from this study supported the notion that secondary aerosols played a significant role in the formation of ambient submicron particulates (PM_0.1−1). Particles smaller than 0.1 μm were essentially basic, whereas those greater than 2.5 μm were neutral or slightly acidic. The neutralization ratio (NR) was close to unity for airborne particles with diameters ranging from 0.18 to 1 μm. The NRs of these airborne particles were found strongly correlated with their sizes, at least for samples taken during the aerosol episodes under study. Insofar as this study is exploratory in nature, as only a small number of particulate samples were used, there appears to be a need for further research into the chemical composition, source contribution, and formation of the nano and ultrafine mode airborne particulates.     

Dependency of polycyclic aromatic hydrocarbon concentrations on particle size distribution in Tehran atmosphere

In this work, the airborne particulate matter with an aerodynamic diameter less than 10 µm (PM₁₀) was fractionated in a six-stage high-volume cascade impactor to identify particulate size distribution in Tehran atmosphere. The study was conducted at 15 sites located in the north, south, east, west, and central parts of Tehran in 2005. Air samples were analyzed for 16 polycyclic aromatic hydrocarbons (PAHs) by HPLC. The daily PM₁₀ concentrations at the peak of traffic in roadside areas were found to be 106–560 µg m^?3. The cumulated concentration sum of PAHs, based on 16 species, was found to have an average concentration of 380 ng m^?3. Furthermore, it was found that more than 60% of PAHs belonged to the small particulate size range, having sizes of less than 0.49 µm, some containing benzo(ghi)perylene and indeno(123cd)pyrene (high molecular weight) with average concentrations of 8 and 6 ng m^?3 and fluorene, phenanthrene, and fluoranthene (low molecular weight) with average concentrations of 14, 13, and 19 ng m^?3, respectively. In addition, the results revealed that the lighter three- and four-ring PAH compounds were the most abundant pollutants in the air collected at all the sampling sites.     

Observation of black carbon aerosol in Beijing, 2003

The objective of this study was to determine the black carbon concentration in Beijing in 2003. The aerosol properties were measured using an Aethalometer and a tapered element oscillating microbalance (TEOM) on the roof of the Physics Building of Peking University (39.99° N, 116.31° E) from July to August 2003 and from November 2003 to January 2004. The average black carbon (BC) concentrations in the summer and winter were 8.80 and 11.4 μg/m³, respectively. During winter, two different cyclone cut offs were installed at the inlet of an aethalometer. The BC mass concentration in TSP, PM₁₀, and PM_2.5 were obtained. The results indicated that in winter aerosol, 90% of BC exited in PM₁₀ and 82.6% of BC exited in PM_2.5. The BC in PM₁₀ accounted for 5.11% of the PM₁₀ mass.