Average Mass Concentrations Of PM2 Research Articles

Integrated evaluation of aerosols during haze-fog episodes at one regional background site in North China Plain

To investigate haze-fog (HF) formation mechanisms and transport, trace gases and aerosols in the aged air masses during regional haze episodes were measured at a regional background site in the North China Plain during 4–19 July, 2011. Mixing state of individual particles, soluble ions of PM2.5, and particle number concentrations were studied using transmission electron microscope, ambient ion monitoring, and wide-range particle spectrometer, respectively. Average mass concentration of PM2.5 was 3 times higher on HF days (70μg/m3) than on clear days (22μg/m3). The major soluble ionic components (SO42−, NO3−, and NH4+) in PM2.5 were over 4 times higher on HF days (40.6μg/m3) than on clear days (9.1μg/m3). The high sulfur oxidation ratios (SOR) and nitrogen oxidation ratios (NOR) values during HF days suggest that polluted weather favored transformation of SO2 and NOx into sulfates and nitrates compared to clear days. Particle number fraction of the accumulation mode increases from 11% on clear days up to 26% on HF days. Individual particle analysis shows that secondary inorganic particles (e.g., sulfate and nitrate) as the most abundant species likely determine internal mixing of individual particles and almost half of them mixed refractory particles (e.g., metal, fly ash, soot, and mineral) on HF days. These fine refractory particles were likely emitted from coal fired power plants, heavy industries, and urban city in Shandong and Hebei provinces. Our results suggest that aged air masses mostly contain aged particles of long-range transport and some from new particle formation and growth in the regional background atmosphere.

Chemical Composition of PM2.5 Based on Two-Year Measurements at an Urban Site in Beijing

In this study, the daily PM2.5 atmospheric aerosols were collected on quartz and PTFE filters simultaneously from January 2008 to December 2009. Organic carbon (OC) and elemental carbon (EC), water-soluble ions including SO42–, NO3–, Cl–, NH4+, K+, Ca2+, and Mg2+ were analyzed for the samples. The annual average mass concentration of PM2.5 for PTFE was 79 µg m–3. The OC, SO42–, NO3–, NH4+ accounted for about 75 % of PM2.5, and secondary organic carbon (SOC) was estimated about 50% of OC. Monthly averages of SO42–, NO3–, NH4+, K+ were maximum in June and minimum in October, but EC, Cl– displayed the highest in December and the lowest in July, which is related to the coal-combustion emission from heating. Three groups with high, medium and low PM2.5 concentrations were categorized. SO42–, NO3–, OC and NH4+ accounted for 24%, 20%, 21% and 11% of sum of defined components in the high concentration days. In the medium and low concentrations, OC occupied large fractions of defined components. Mass closure was obtained for PTFE, but not for quartz. The PM2.5 mass concentrations on quartz filters were about 50 µg m–3 higher than that on PTFE. The concentrations of water soluble ions on quartz filters were about 60–70% of that on PTFE filters. About 15–30% of PM2.5 was considered as the contribution of water vapor, the artifact of water vapor on quartz filter should be noted in later research works. PM2.5 displayed neutral during the year of 2008 and appeared acidic at the next year according to the calculation of cations/anion, concentration of hydrogen and acidic purity. Carbonaceous aerosols occupied same fractions in neutral and acidic aerosols. While sulfate and nitrate contributed 32% and 21% to PM2.5 for acidic aerosols, and 22%, 17% of PM2.5 from sulfate and nitrate for neutral aerosols.

Aerosol characteristics at a rural station in southern peninsular India during CAIPEEX-IGOC: physical and chemical properties.

To understand the boundary layer characteristics and pathways of aerosol-cloud interaction, an Integrated Ground Observational Campaign, concurrent with Cloud Aerosol Interaction and Precipitation Enhancement Experiment, was conducted by the Indian Institute of Tropical Meteorology, Pune, under Ministry of Earth Sciences at Mahabubnagar (a rural environment, which is ~100 km away from an urban city Hyderabad in Andhra Pradesh), during the period of July-November 2011. Collected samples of PM2.5 and PM10 were analyzed for water-soluble ionic species along with organic carbon (OC) and elemental carbon (EC). During study period, the average mass concentrations of PM2.5 and PM10 were about 50(±10) and 69(±14) μg m(-3), respectively, which are significantly higher than the prescribed Indian National Ambient Air Quality Standards values. The chemical species such as sum of anions and cations from measured chemical constituents were contributed to be 31.27 and 38.49% in PM2.5 and 6.35 and 5.65% to the PM10, whereas carbonaceous species contributed ~17.3 and 20.47% for OC and ~3.0 and 3.10% for EC, respectively. The average ratio of PM2.5/PM10 during study period was ~0.73(±0.2), indicating that the dominance of fine size particles. Carbonaceous analysis results showed that the average concentration of OC was 14 and 8.7 μg m(-3), while EC was 2.1 and 1.5 μg m(-3) for PM10 and PM2.5, respectively. The ratios between OC and EC were estimated, which were 6.6 and 5.7 for PM10 and PM2.5, suggesting the presence of secondary organic aerosol. Total carbonaceous aerosol accounts 23% of PM10 in which the contribution of OC is 20% and EC is 3%, while 20% of PM2.5 mass in which the contribution of OC is 17% and EC is 3%. Out of the total aerosols mass, water-soluble constituents contributed an average of 45% in PM10 and 38% in PM2.5 including about 39% anions and 6% cations in PM10, while 31% anions and 7% cations in PM2.5 aerosol mass collectively at study site.

Study of carbonaceous species, morphology and sources of fine (PM2.5) and coarse (PM10) particles along with their climatic nature in India

The determination of particulate matter (PM2.5 and PM10) is very important due to its impact on climate, visibility reduction and natural environment. In order to identify their nature and relationship with the major synoptic-scale circulation patterns, particles were collected from Pune atmosphere and were analyzed in terms of morphology, carbonaceous species (organic and elemental carbon) and elemental concentration. Average mass concentrations of PM2.5 and PM10 were 104.57±25.70μgm−3 and 169.91±60.75μgm−3, respectively for the entire study period. This indicates that observed values of PM are substantially higher than NAAQS and WHO standards, respectively. The ratio between PM2.5 and PM10 was calculated and varied from 0.51 to 0.78 indicating abundance of fine particles over Pune during the study period. Carbonaceous analysis results showed that concentrations of OC and EC were 31.25 and 2.73μgm−3 for PM2.5 while 33.14 and 2.40μgm−3 for PM10, respectively. The calculated OC/EC ratios were 15.83 and 17.24 for PM2.5 and PM10, respectively indicating abundance of organic carbon which suggests the excess of secondary organic aerosols. The morphological traits such as circularity (<1) and aspect ratio (>1) were determined which indicate that the particles are not perfectly spherical and not elongated in any direction in both size ranges. Effective carbon ratio (ECR) an approach for climate was found to have an average value of 2.42 and 1.74 for PM2.5 and PM10. This clearly indicates that abundance of SOC and lower values of POC and EC could lead to the reduction in atmospheric warming effect due to combustion PM and increases scattering properties of incoming radiations. The monthly air mass backward trajectory cluster analysis was performed which supports the transport of aerosols from the long range transportation as well as the dominance of local sources over SW Indian region. The contribution of local sources was further determined which indicates that motor vehicle is the dominant emitter of carbonaceous aerosols in Pune.

Sources and characteristics of carbonaceous aerosols at Agra "World heritage site" and Delhi "capital city of India".

Agra, one of the oldest cities "World Heritage site", and Delhi, the capital city of India are both located in the border of Indo-Gangetic Plains (IGP) and heavily loaded with atmospheric aerosols due to tourist place, anthropogenic activities, and its topography, respectively. Therefore, there is need for monitoring of atmospheric aerosols to perceive the scenario and effects of particles over northern part of India. The present study was carried out at Agra (AGR) as well as Delhi (DEL) during winter period from November 2011 to February 2012 of fine particulate (PM₂.₅: d < 2.5 μm) as well as associated carbonaceous aerosols. PM₂.₅ was collected at both places using medium volume air sampler (offline measurement) and analyzed for organic carbon (OC) and elemental carbon (EC). Also, simultaneously, black carbon (BC) was measured (online) at DEL. The average mass concentration of PM₂.₅ was 165.42 ± 119.46 μg m(-3) at AGR while at DEL it was 211.67 ± 41.94 μg m(-3) which is ~27% higher at DEL than AGR whereas the BC mass concentration was 10.60 μg m(-3). The PM₂.₅ was substantially higher than the annual standard stipulated by central pollution control board and United States Environmental Protection Agency standards. The average concentrations of OC and EC were 69.96 ± 34.42 and 9.53 ± 7.27 μm m(-3), respectively. Total carbon (TC) was 79.01 ± 38.98 μg m(-3) at AGR, while it was 50.11 ± 11.93 (OC), 10.67 ± 3.56 μg m(-3) (EC), and 60.78 ± 14.56 μg m(-3) (TC) at DEL. The OC/EC ratio was 13.75 at (AGR) and 5.45 at (DEL). The higher OC/EC ratio at Agra indicates that the formation of secondary organic aerosol which emitted from variable primary sources. Significant correlation between PM₂.₅ and its carbonaceous species were observed indicating similarity in sources at both sites. The average concentrations of secondary organic carbon (SOC) and primary organic carbon (POC) at AGR were 48.16 and 26.52 μg m(-3) while at DEL it was 38.78 and 27.55 μg m(-3), respectively. In the case of POC, similar concentrations were observed at both places but in the case of SOC higher over AGR by 24 in comparison to DEL, it is due to the high concentration of OC over AGR. Secondary organic aerosol (SOA) was 42% higher at AGR than DEL which confirms the formation of secondary aerosol at AGR due to rural environment with higher concentrations of coarse mode particles. The SOA contribution in PM₂.₅ was also estimated and was ~32 and 12% at AGR and DEL respectively. Being high loading of fine particles along with carbonaceous aerosol, it is suggested to take necessary and immediate action in mitigation of the emission of carbonaceous aerosol in the northern part of India.

Investigation of the sources and evolution processes of severe haze pollution in Beijing in January 2013

AbstractChina experienced severe haze pollution in January 2013. Here we have a detailed characterization of the sources and evolution mechanisms of this haze pollution with a focus on four haze episodes that occurred during 10–14 January in Beijing. The main source of data analyzed is from submicron aerosol measurements by an Aerodyne Aerosol Chemical Speciation Monitor. The average PM1 mass concentration during the four haze episodes ranged from 144 to 300 µg m−3, which was more than 10 times higher than that observed during clean periods. All submicron aerosol species showed substantial increases during haze episodes with sulfate being the largest. Secondary inorganic species played enhanced roles in the haze formation as suggested by their elevated contributions during haze episodes. Positive matrix factorization analysis resolved six organic aerosol (OA) factors including three primary OA (POA) factors from traffic, cooking, and coal combustion emissions, respectively, and three secondary OA (SOA) factors. Overall, SOA contributed 41–59% of OA with the rest being POA. Coal combustion OA (CCOA) was the largest primary source, on average accounting for 20–32% of OA, and showed the most significant enhancement during haze episodes. A regional SOA (RSOA) was resolved for the first time which showed a pronounced peak only during the record‐breaking haze episode (Ep3) on 12–13 January. The regional contributions estimated based on the steep evolution of air pollutants were found to play dominant roles for the formation of Ep3, on average accounting for 66% of PM1 during the peak of Ep3 with sulfate, CCOA, and RSOA being the largest fractions (&gt; ~ 75%). Our results suggest that stagnant meteorological conditions, coal combustion, secondary production, and regional transport are four main factors driving the formation and evolution of haze pollution in Beijing during wintertime.

Major chemical compositions, possible sources, and mass closure analysis of PM2.5 in Jinan, China

The fine particulate matter samples for 24 h were carried out at the Environment Monitoring Station (EMS) and Shandong Jianzhu University (SJU) sites during 2010 in Jinan City, China. Eight water-soluble ion species were analyzed by ion chromatography, while organic carbon (OC) and elemental carbon (EC) were determined with the IMPROVE thermal optical reflectance method, and 20 inorganic elements were measured by inductively coupled plasma-atomic emission spectrometer and inductively coupled plasma-mass spectroscopy. The annual average mass concentration of PM2.5 was 168.85 μg m−3 at EMS and 148.67 μg m−3 at SJU. The coefficient of divergence was 0.14, 0.19, 0.23, and 0.23 in spring, summer, fall, and winter, respectively, indicating that there was no obvious spatial difference at the two sampling sites. The highest PM2.5, OC, and OC/EC ratio were in winter because of the enhanced emissions from coal combustion for heating and poor atmospheric dispersion. By the method of enrichment factors, the 20 inorganic elements were divided into three types owing to their sources. Al, Si, and Ti were mainly contributed by crustal sources. Na, Mg, P, K, Ca, V, Cr, Mn, Fe, Co, Ni, Ba, and Sr were from both natural emissions and anthropogenic sources. Cu, Zn, Pb, and Sn mainly originated from anthropogenic sources such as vehicular exhaust and industrial emission. Chemical mass closure calculation estimated that SO4 2− was the largest contributor and explained 29.66 % of PM2.5 mass at EMS, while 31.64 % was at SJU. The organic matter, crustal matter, and NO3 –, respectively, accounted for 15.12, 12.87, and 13.77 % to PM2.5 at EMS, while it accounted for 13.46, 13.96, and 14.93 % at SJU, respectively. By the positive matrix factorization analysis, the coal combustion and biomass burning, secondary sulfate, soil dust, secondary nitrate, and vehicle emissions were identified as the major emission sources.

Environment Analysis on Controlling PM2.5 in Beijing

PM2.5 pollution in Beijing not only causes the greatest health problems, and reduces the visibility (haze), but also impacts on the China governments credibility and international image. The paper showed that the average mass concentration of PM2.5 in Beijing was 103μg/m 3 in the first half year of 2013; the annual mean mass concentration of PM2.5 has risen in recent years; the transfer of regional pollution, motor vehicles, coal combustion and dust are the major sources of PM2.5 during 2012 in Beijing; and finally the government should take effective measures to control PM2.5. The paper may provide some theoretical guidance for the government implementing environmental protection policy and pollution control measures.

Study of Surface Morphology, Elemental Composition and Origin of Atmospheric Aerosols (PM2.5 and PM10) over Agra, India

In situ measurements of PM (PM2.5 and PM10) particles were carried out using a medium volume air sampler (offline) and particle number concentrations of PM were measured by a Grimm aerosol spectrophotometer (online) during the study period of 2010–2011. The morphology and elemental composition analyses of PM were performed by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrometry (EDS), respectively. The average mass concentrations of PM2.5 and PM10 were 97.2 and 242.6 µg/m 3 at roadside (RD) and 121.2 and 230.5 µg/m 3 at a semirural (SR) site, respectively. These concentrations were substantially higher than the NAAQS, WHO and USEPA standards. The highest mass and number concentrations of PM2.5 and PM10 were observed during winter, followed by those during the post-monsoon period and summer, with the lowest in the monsoon period. SEM and EDS analysis of PM indicated the presence of soot, mineral, tarballs, fly ash, aluminosilicates/silica, fluorine, carbon rich, and Cl-Na rich particles. Of these particles, soot, tarballs, and F-C rich particles dominate in PM2.5, whereas mineral, aluminosilicates, and Cl-Na rich particles dominate in PM10. The morphology and elemental composition of the particles varied over the seasons due to atmospheric processing. The highest carbon concentration (56%) was observed in PM2.5 during summer at the RD, while in the monsoon, postmonsoon period and winter the carbon concentration was ~9% lower at the RD as compared to the SR. However, the concentration of carbon in PM10 was ~38% higher at the RD as compared to SR during both summer and winter. Air mass backward trajectory cluster analysis was performed, and the results indicate that the aerosol loadings over Agra are mainly transported from the Middle East and Arabian Sea during the summer and monsoon period, while during the pre-monsoon period and winter the aerosol loadings came from the northern region, and were due to the burning of biomass and coal, as well as other local activities.

Airborne submicron particulate (PM1) pollution in Shanghai, China: Chemical variability, formation/dissociation of associated semi-volatile components and the impacts on visibility

Hourly mass concentrations of water-soluble ions in PM1 and gasses (NH3, HNO3, HCl) were on-line measured with a Monitor for AeRosols and Gases Analyzer (MARGA) in Shanghai from Oct. 1 to Nov. 16, 2012. During the field campaign, 7 haze episodes (total 157h) were identified. 845h were identified as non-haze periods, excluding fog events and wet precipitation. The average mass concentration of PM1 and total water-soluble ions (TWSI) in PM1 in haze episodes were 78.9±29.9μg/m3 and 47.2±17.2μg/m3, 3.11 times (from 1.49 to 4.06 times) and 3.28 times (1.96 to 4.34 times) as those in non-haze periods, respectively. TWSI accounted for 60.4±18.8% of PM1 mass loading in the whole campaign. With the ascending PM1 mass concentration from 2.5 to 125.0μg/m3 from non-haze periods to haze episodes, average contribution of TWSI to PM1 mass loading decreased from 86.1% to 54.2%, while different species altered. Contribution of NO3− increased from 14.0% to 26.8%, while SO42− decreased from 39.5% to 15.0% and NH4+ remained around 13.7%. Relationship of visibility with PM1 and TWSI was addressed in specific RH ranges. It was found that hourly TWSI mass concentration showed better correlation with visibility. Formation/dissociation of semi-volatiles (NH4NO3 and NH4Cl) was also investigated and demonstrated. NH4NO3 and NH4Cl tended to partition into gas phase in non-haze periods. Particularly, strong dissociation from 11:00 LT to 17:00 LT was observed. In haze episodes, HNO3 and HCl tended to react with NH3 to form particulate matters. Interestingly, we found that formation/dissociation of NH4NO3 and NH4Cl exerted great impacts on visibility. Excluding the strong dissociation hours (11:00 LT to 17:00 LT) in correlation analysis of PM1 and visibility, correlation coefficients (R2) increased from 0.5762 to 0.7738 at RH<50%. No significant difference was observed in other RH ranges. In addition, Strong NH3 and HNO3 reaction resulted in the enhancement of NH4NO3 mass fraction, therefore increased associated water content in PM1 under high RH condition and contributed to visibility degradation.

Insights on organic aerosol aging and the influence of coal combustion at a regional receptor site of central eastern China

Abstract. In order to understand the aging and processing of organic aerosols (OA), an intensive field campaign (Campaign of Air Pollution at Typical Coastal Areas IN Eastern China, CAPTAIN) was conducted March–April at a receptor site (a Changdao island) in central eastern China. Multiple fast aerosol and gas measurement instruments were used during the campaign, including a high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) that was applied to measure mass concentrations and non-refractory chemical components of submicron particles (PM1nr). The average mass concentration of PM1(PM1nr+black carbon) was 47 ± 36 μg m−3 during the campaign and showed distinct variation, depending on back trajectories and their overlap with source regions. Organic aerosol (OA) is the largest component of PM1 (30%), followed by nitrate (28%), sulfate (19%), ammonium (15%), black carbon (6%), and chloride (3%). Four OA components were resolved by positive matrix factorization (PMF) of the high-resolution spectra, including low-volatility oxygenated organic aerosol (LV-OOA), semi-volatile oxygenated OA (SV-OOA), hydrocarbon-like OA (HOA) and a coal combustion OA (CCOA). The mass spectrum of CCOA had high abundance of fragments from polycyclic aromatic hydrocarbons (PAHs) (m/z 128, 152, 178, etc.). The average atomic ratio of oxygen to carbon in OA (O / C) at Changdao was 0.59, which is comparable to other field studies reported at locations downwind of large pollution sources, indicating the oxidized nature of most OA during the campaign. The evolution of OA elemental composition in the van Krevelen diagram (H / C vs. O / C) showed a slope of −0.63; however, the OA influenced by coal combustion exhibits a completely different evolution that appears dominated by physical mixing. The aging of organic aerosols vs. photochemical age was investigated. It was shown that OA / ΔCO, as well as LV-OOA / ΔCO and SV-OOA / ΔCO, positively correlated with photochemical age. LV-OOA accounted for 73% of the OA secondary formation (SOA) in the oldest plumes (photochemical age of 25 h). The kOH at Changdao, by assuming SOA formation and aging as a first-order process proportional to OH, was calculated to be 5.2 × 10−12 cm3 molec.−1 s−1, which is similar to those determined in recent studies of polluted air in other continents.

Characteristics and Sources of Carbonaceous Aerosols in PM2.5 during Wintertime in Agra, India

PM2.5 samples were collected at traffic, rural and campus sites in Agra during Nov 2010 to Feb 2011 and characterized for carbonaceous aerosols. The average mass concentrations of PM2.5 were 308.3 ± 51.8 μg/m3, 91.2 ± 17.3 μg/m3 and 140.8 ± 22.3 μg/m3 at the traffic, rural and campus sites, respectively. The 24-h mass concentrations of PM2.5 were significantly higher than the limit of 60 μg/m3 prescribed in the National Ambient Air Quality Standards (Indian NAAQS) and 25 μg/m3 of those of the WHO (World Health Organization). The average concentrations of OC (organic carbon) and EC (elemental carbon) were 86.1 ± 5.2 and 19.4 ± 2.4 at the traffic site, 30.3 ± 12.9 and 4.0 ± 1.5 at the rural site and 44.5 ± 18.5 μg/m3 5.0 ± 1.4 μg/m3 at the campus one. The contributions of TCA (Total Carbonaceous Aerosol) at the traffic, campus and rural sites were found to be 52, 54 and 58% of PM2.5 mass, respectively. A significant correlation was observed between water soluble K+ and OC at the rural (R2 = 0.63) and campus (R2 = 0.53) sites compared to the traffic one (R2 = 0.35). This may be attributed to increased biomass burning emissions at the rural and campus sites. The concentrations of SOC (Secondary Organic Carbon) were estimated based on the minimum OC/EC ratio, and were found to be 15.3 ± 6.3, 8.2 ± 5.8 and 28.8 ± 15.8 μg/m3, accounting for 18, 24.7 and 60.7% of total OC at the traffic, rural and campus sites, respectively. The surface morphology of the particles was analyzed by scanning electron microscopy and energy- dispersive X-ray spectroscopy (SEM/EDX). The results indicated branched chain-like aggregates of carbon bearing spheres at the traffic and rural sites, while at the campus site carbon-rich and minerogenic (mineral dust) particles were the dominant ones.

Physicochemical and toxicological characteristics of urban aerosols during a recent Indonesian biomass burning episode

Air particulate matter (PM) samples were collected in Singapore from 21 to 29 October 2010. During this time period, a severe regional smoke haze episode lasted for a few days (21-23 October). Physicochemical and toxicological characteristics of both haze and non-haze aerosols were evaluated. The average mass concentration of PM2.5 (PM with aerodynamic diameter of ≤2.5 μm) increased by a factor of 4 during the smoke haze period (107.2 μg/m(3)) as compared to that during the non-smoke haze period (27.0 μg/m(3)). The PM2.5 samples were analyzed for 16 priority polycyclic aromatic hydrocarbons (PAHs) listed by the United States Environmental Protection Agency and 10 transition metals. Out of the seven PAHs known as potential or suspected carcinogens, five were found in significantly higher levels in smoke haze aerosols as compared to those in the background air. Metal concentrations were also found to be higher in haze aerosols. Additionally, the toxicological profile of the PM2.5 samples was evaluated using a human epithelial lung cell line (A549). Cell viability and death counts were measured after a direct exposure of PM2.5 samples to A459 cells for a period of 48 h. The percentage of metabolically active cells decreased significantly following a direct exposure to PM samples collected during the haze period. To provide further insights into the toxicological characteristics of the aerosol particles, glutathione levels, as an indirect measure of oxidative stress and caspase-3/7 levels as a measure of apoptotic death, were also evaluated.

Fine scale modeling of wintertime aerosol mass, number, and size distributions in central California

In light of nonattainment of PM2.5 in central California, the CMAQ‐MADRID 1 model is applied to simulate PM2.5 mass, number, and size distributions observed during the California Regional PM10/PM2.5 Air Quality Study (CRPAQS) winter episode of 25–31 December 2000. The simulations with 12 and 24 size sections at a horizontal grid resolution of 4 km reproduce well the 24 h average mass concentrations of PM2.5 (with normalized mean biases (NMBs) of −6.2% to 0.5%), but with larger biases for organic matter, nitrate, and elemental carbon (with NMBs of −67% to 40.2%) and a weaker capability of replicating temporal variation of PM2.5 and its components. The coagulation process leads to a 40%–91% reduction in simulated PM2.5 number concentrations. The 24 section simulation with coagulation shows the best agreement with the observed PM number and size distributions (with an NMB of −13.9%), indicating the importance of coagulation for predicting particle number and the merits of using a fine particle size resolution. Accurately simulating PM2.5 number and size distributions continue to be a major challenge, due to inaccuracies in model inputs (e.g., meteorological fields, precursor emissions, and the initial size distribution of PM emissions and concentrations), uncertainties in model formulations (e.g., heterogeneous chemistry and aerosol formation, growth, and removal processes), as well as inconsistencies and uncertainties in observations obtained with different methods.

Characteristics of elemental composition of PM2.5 in the spring period at Tongyu in the semi-arid region of Northeast China

Continuous observations of mass concentration and elemental composition of aerosol particles (PM2.5) were conducted at Tongyu, a semi-arid site in Northeast China in the spring of 2006. The average mass concentration of PM2.5 at Tongyu station was 260.9±274.4 µg m−3 during the observation period. Nine dust events were monitored with a mean concentration of 528.0±302.7 µg m−3. The PM2.5 level during nondust storm (NDS) period was 111.65±63.37 µg m−3. High mass concentration shows that fine-size particles pollution was very serious in the semi-arid area in Northeast China. The enrichment factor values for crust elements during the dust storm (DS) period are close to those in the NDS period, while the enrichment factor values for pollution elements during the NDS period are much higher than those in the DS period, showing these elements were from anthropogenic sources. The ratios of dust elements to Fe were relative constant during the DS period. The Ca/Fe ratio in dust aerosols at Tongyu is remarkably different from that observed in other source regions and downwind regions. Meteorological analysis shows that dust events at Tongyu are usually associated with dry, low pressure and high wind speed weather conditions. Air mass back-trajectory analysis identified three kinds of general pathways were associated with the aerosol particle transport to Tongyu, and the northwest direction pathway was the main transport route.

Particulate and Ionic Species Near Highway Traffic During Day and Night

Ambient air particulate concentrations were sampled using an RP2300 Sampler (RP 2300, Rupprecht and Patashnick, CO, USA) from March 4 to April 2, 2006, at a sampling site near highway traffic. However particles that have an aerodynamic diameter of less than 10 μm (0.01 mm) are called respiratory particulates or particulate matter (PM10). PM2.5 denotes fine particles with an aerodynamic diameter of less than 2.5 μm (Ohlstrom et al., 2000). Analysis results indicated that the average mass concentrations of fine particles (PM2.5) and inhalable particles (PM10) were 64.43 and 109.20 μ g/m3, respectively, during the day. The average mass concentrations of PM2.5 and PM10 were 69.45 and 110.46 μ g/m3 during the night. Average concentrations of major ionic species, NO2 −, NO3 −, SO4 2 −, and NH4 + during the day were 2.37, 9.16, 13.72, and 7.70 μ g/m3 in PM2.5 and 3.72, 16.42, 16.90, and 8.91 μ g/m3 in PM10. The corresponding values at night were 3.29, 11.77, 11.55, and 8.03 μ g/m3 in PM2.5 and 3.87, 18.13, 14.27, and 9.98 μ g/m3 in PM10. However, t-test results revealed that the concentrations of ionic species (Cl−, NO2 −, NH4 +, Mg2 +, and Ca2 +) in PM2.5 during the day did not differ significantly from those at night. T-test results revealed that the ionic species (NO3 −, SO4 2 −, Na+, and K+) concentrations in PM2.5 during the day differ, significantly from those at night. The concentrations of ionic species (Cl−, NO2 −, NO3 −, and NH4 +) in PM10 during the day did not differ significantly from those at night. The concentrations of ionic species (SO4 2 −, Na+, K+, Mg2 +, and Ca2 +) in PM10 during the day differed significantly from those at night. The concentration of Cl− in PM2.5 is negatively correlated (r = −0.62) with the temperature during the day at this site close to highway traffic. Furthermore, a comparison with previous results (Fang et al., 1999a) revealed that the average concentration of NO3 − increased by 32% and 46% in PM2.5 and PM10, respectively, during the day. Average concentrations of NO3 − were increased by 72% and 65% in PM2.5 and PM10, respectively, during the night. Average concentrations of SO4 2 − were decreased by 10% and 7% in PM2.5 and PM10, respectively, during the day. Finally, average concentrations of SO4 2 − were decreased by 72% and 62% in PM2.5 and PM10, respectively, during the night. This monitoring data may be helpful to establish baseline or background concentrations, which is essential for forensic investigations.

Semi-Continuous Aerosol Measurement for Visibility Variation Using an External Beam PIXE Method

This study introduces the application of a semi-continuous monitoring and analytic technique to examine the elemental composition for a visibility-impairing aerosol. Semi-continuous measurements of the chemical composition for visibility-impairing aerosol were made during the spring period of 19 30 May 2007 in the urban area of Seoul, Korea. These included measurements of the aerosol elemental composition by a proton induced X-ray emission (PIXE) method, of the aerosol ionic composition by ion chromatography (IC) method and of the aerosol carbonaceous composition by a thermal optical transmittance (TOT) method. Light extinction, scattering and absorption coe cients were measured simultaneously with a transmissometer, a nephelometer and an aethalometer, respectively. The average light extinction coe cient and visual range were measured to be 343 186 Mm 1 and 11.8 4.2 km, respectively, during the intensive monitoring period. The average mass concentrations of PM1:0, PM2:5 and PM10 were measured to be 24.0 13.4, 44.6 30.6 and 77.0 56.1 g m 3 and the correlation coe cient r2 of submicron and ne particles to bext were calculated to be relatively higher values of 0.7835 and 0.7824, respectively. However, the value of r2 for coarse particles was a low value of 0.1261. The results revealed that visibility impairment in the urban atmosphere of Seoul was a ected by ne particles, including submicron particles, rather than coarse particles. On a clear day and a hazy day, the mass concentration of mineral dust was not sensitive to variations in bext. On an Asian dust event day, visibility degradation was dominantly caused by increases in the SO2 4 and the NO 3 components between 12:00 and 14:00, during which time they combined with a large loading of mineral dust caused severely reduced visibility. The ability to observe rapid changes in the aerosol composition using semi-continuous aerosol measurements and the PIXE method was helpful in understanding the diurnal variation of visibility.

Effect of Meteorological Parameters on Fine and Coarse Particulate Matter Mass Concentration in a Coal-Mining Area in Zonguldak, Turkey

In this work, the effect of meteorological parameters and local topography on mass concentrations of fine (PM2.5) and coarse (PM2.5–10) particles and their seasonal behavior was investigated. A total of 236 pairs of samplers were collected using an Anderson Dichotomous sampler between December 2004 and October 2005. The average mass concentrations of PM2.5, PM2.5–10, and particulate matter less than 10 μm in aerodynamic diameter (PM10) were found to be 29.38, 23.85, and 53.23 μ/m3, respectively. The concentrations of PM2.5 and PM10 were found to be higher in heating seasons (December to May) than in summer The increase of relative humidity, cloudiness, and lower temperature was found to be highly related to the increase of particulate matter (PM) episodic events. During non-rainy days, the episodic events for PM2.5 and PM10 were increased by 30 and 10.7%, respectively. This is a result of the extensive use of fuel during winter for heating purposes and also because of stagnant air masses formed because of low temperature and low wind speed over the study area.

Assessing Exposure to Diesel Exhaust Particles: A Case Study

The assessment of the vehicular contributions to urban pollution levels is of particular importance given the current interest in the possible adverse health effects. This study focused on human exposure to diesel-engine-derived particulate matter. Diesel vehicles are known to emit fine particulate matter (PM2.5) containing carcinogens such as polycyclic aromatic hydrocarbons (PAHs), and have therefore received considerable attention. In this study, the physical (mass and number concentration, and size distribution) and chemical (PAHs) properties were investigated at a major bus interchange in Singapore, influenced only by diesel exhausts. Number concentration and size distribution of particles were determined in real time, while the mass concentrations of PM2.5, and PAHs were measured during operating and nonoperating hours. The average mass concentrations of PM2.5 and PAHs increased by a factor of 2.34 and 5.18, respectively, during operating hours. The average number concentration was also elevated by a factor of 5.07 during operating hours. This increase in the concentration of PM2.5 particles and their chemical constituents during operating hours was attributable to diesel emissions from in-use buses based on the particle size analysis, correlation among PAHs, and the commonly used PAHs diagnostic ratios. To evaluate the potential health threat due inhalation of air pollutants released from diesel engines, the incremental lifetime cancer risk was also calculated for a maximally exposed individual. The findings indicate that the air quality at the bus interchange poses adverse health effects.

Comprehensive characterization of PM2.5 aerosols in Singapore

A comprehensive characterization of PM2.5 aerosols collected in Singapore from January through December 2000 is presented. The annual average mass concentration of PM2.5 was 27.2 μg/m3. The atmospheric loading of PM2.5 was elevated sporadically from March through May, mainly due to advection of biomass burning (deliberate fires to clear plantation areas) impacted air masses from Sumatra, Indonesia. Satellite images of the area, trajectory calculations, and surface wind direction data are in support of the transport of pyrogenic products from Sumatra toward Singapore. Aerosol samples collected during the dry season were analyzed for water‐soluble ions, water‐soluble organic compounds (WSOC), elemental carbon (EC), organic carbon, and trace elements using a number of analytical techniques. The major components were sulfate, EC, water‐soluble carbonaceous materials, and water‐insoluble carbonaceous materials. Aerosol WSOC were characterized based on a combination of chromatographic separations by ion exchange chromatography, functional group investigation by proton nuclear magnetic resonance, and total organic carbon determination. The comprehensive chemical characterization of PM2.5 particles revealed that both non‐sea‐salt sufate (nss‐SO42−) and carbonaceous aerosols mainly contributed to the increase in the mass concentration of aerosols during the smoke haze period. Using a mass closure test (a mass balance), we determined whether the physical measurement of gravimetric fine PM concentration of a sample is equal to the summed concentrations of the individually identified chemical constituents (measured or inferred) in the sample. The sum of the determined groups of aerosol components and the gravimetrically determined mass agreed reasonably well. Principal component analysis was performed from the combined data set, and five factors were observed: a soil dust component, a metallurgical industry factor, a factor representing emissions from biomass burning and automobiles, a sea‐salt component, and an oil combustion factor.