Showing papers in "Aerosol and Air Quality Research in 2011"

Analysis of the Relationship between O3, NO and NO2 in Tianjin, China

Abstract: The continuous measurement of nitric oxide (NO), nitrogen dioxide (NO2), nitrogen oxides (NO(subscript x)) and ozone (O3) was conducted in Tianjin from September 8 to October 15, 2006. The data were used to investigate the relationship between the O3 distribution and its association with ambient concentrations of NO, NO2 and NO(subscript x) (NO and NO2). The measured concentrations of the pollutants in the study area varied as a function of time, while peaks in NO, NO2 and O3 all occurred in succession in the daytime. The diurnal cycle of ground-level ozone concentration showed a mid-day peak and lower nighttime concentrations. Furthermore, an inverse relationship was found between O3 NO, NO2 and NO(subscript x). In addition, a linear relationship between NO2 and NO(subscript x), as well as NO and NO(subscript x), and a polynomial relationship between O3 and NO2/NO was found. The variation in the level of oxidant (O3 and NO2) with NO2 was also obtained. It can be seen that OX concentration at a given location is made up of two parts: one independent and the other dependent on NO2 concentration. The independent part can be considered as a regional contribution and is about 20 ppb in Tianjin. An obvious difference in NO, NO(subscript x) and O3 concentrations between weekdays and weekends was also found, but this difference did not appear in NO2. Lastly, the diurnal variation of O3 concentration under different meteorological conditions was demonstrated and analyzed.

Post-processing Method to Reduce Noise while Preserving High Time Resolution in Aethalometer Real-time Black Carbon Data

Abstract: Real-time aerosol black carbon (BC) data, presented at time resolutions on the order of seconds to minutes, is desirable in field and source characterization studies measuring rapidly varying concentrations of BC. The Optimized Noisereduction Averaging (ONA) algorithm has been developed to post-process data from the Aethalometer, one of the widely used real-time BC instruments. The ONA program conducts adaptive time-averaging of the BC data, with the incremental light attenuation (∆ATN) through the instrument’s internal filter determining the time window of averaging. Analysis of instrument noise and the algorithm performance was conducted using Aethalometer 1-second data from a soot generation experiment, where input BC concentrations were maintained constant and an optimal ∆ATNmin value was defined. The ONA procedure was applied to four additional data sets (1 s to 5 min data), including cookstove emissions tests, mobile monitoring, continuous near-road measurements, and indoor air sampling. For these data, the algorithm reduces the occurrence of negative values to virtually zero while preserving the significant dynamic trends in the time series.

Seasonal Variation and Sources of Heavy Metals in Atmospheric Aerosols in a Residential Area of Ulsan, Korea

Abstract: This study investigated seasonal variations in mass concentrations of particulate matter (PM) and compositions of heavy metals in PM2.5 and PM10 collected from a typical urban residential area in Ulsan, Korea. PM measurements were conducted during spring and summer of 2009. Mean concentrations of PM2.5 in spring and summer were 23.2 and 18.1 µg/m 3 , respectively. Mean concentrations of PM10 in spring and summer were 45.9 and 33.2 µg/m 3 , respectively. The lower summer PM concentrations as compared to the spring ones are due to the increased rainfall precipitation. Airborne PM was analyzed for these heavy metals: Fe, Zn, Cd, Mn, Pb, Cu, Cr and Ni. All of the metals in PM2.5 and PM10 had higher concentrations in spring than in summer, except Cr in PM10 which shows similar concentrations between spring and summer. Seasonal differences in the metal concentrations may be due to differences in wind directions with some winds passing through industry or traffic areas. Analysis of enrichment factors of heavy metals showed highly enriched Cd, Zn, Pb and Cu. Principal component analysis for the heavy metals in PM2.5 and PM10 identified industrial emissions and road dust (soil and traffic) as major sources at the sampling site.

Water soluble ions in PM2.5 and PM1 aerosols in durg city, Chhattisgarh, India

Abstract: This paper reports the atmospheric concentrations of PM2.5 and PM1 mass, water soluble inorganic components and their seasonal variations measured between the period of July 2009 and June 2010 in Durg city (20°23' to 22°02'N and 80°46' to 81°58'E), India. A cascade impactor sampler with Whatman 41 glass filters was used to collect aerosol samples in PM2.5 and PM1 size fractions. The results showed that the annual mean concentration of PM2.5 and PM1 were 135.0 µg/m3 and 64.7 µg/m3, respectively. Annual cycle shows highest concentration of PM2.5 and PM1 mass and water soluble ions in winter season and the lowest during rainy season. This is attributed to the enhanced production of aerosols and prevailing meteorological conditions. The higher PM1/PM2.5 ratio (0.48) during the whole campaign clearly indicates larger PM1 particle fractions were in PM2.5 at this location. Out of the total aerosol mass, water soluble constituents contributed an average of 11.57% (7.48% anions, 4.09% cations) in PM2.5 and 16.98% (11.14% anions, 5.85% cations) in PM1. The concentrations of SO42- and NO3- were highest in all size fractions and accounted for 32.76% and 13.38% of the total mass of the water soluble ions in PM2.5 and 32.78% and 12.21% in PM1 size fractions. Na+, Mg2+ and Ca2+, derived from the soil dust particles, were higher in spring and summer, as the dry weather in this season was favorable for the resuspension of soil particles. The seasonal variation of Cl-, K+ and secondary components (NH4+, NO3- and SO42-) were similar with high concentrations in winter and low concentrations in fall. Two principal components explaining 76.6% and 65.9% of the variance for PM2.5 and PM1 data set respectively were identified. Factor 1 has significant loading of species of anthropogenic origins and factor 2 showed partial associations with species of natural origins.

Chemical Characterization and Source Identification of Particulate Matter at an Urban Site of Navi Mumbai, India

Abstract: Particulate matter samples were collected using a dichotomous sampler at a residential area of Vashi situated in Navi Mumbai, India during the period of 2008. The sampler facilitates the simultaneous collection of atmospheric particulates in coarse and fine size fractions. The filter samples collected were analysed for trace elements using Proton Induced X-ray Emission (PIXE) technique. The particulate matter trends show higher concentration during winter season compared to other seasons. High concentrations of elements related to soil and sea salt were found in the coarse fraction of particulate matter. Enrichment Factor (EF) analysis with respect to Fe showed enrichment of Cu, Cr, and Mn only in the fine fraction suggesting their origin from anthropogenic sources. The EF value was observed to be maximum for As, Pb and Zn in the fine particulates. However, crustal and marine derived elements showed very low EF values indicating their origin from soil and sea salt respectively. The Principal Component Analysis (PCA) based multivariate studies identified soil, sea salt and combustion as common sources for coarse and fine particles. Additionaly a source contributing to coarse fraction Br concentration as well as an industrial and Se source contributing to fine fraction particles has been identified.

Estimation of the Main Factors Influencing Haze, Based on a Long-term Monitoring Campaign in Hangzhou, China

Abstract: Eight years of data on haze and visibility (2003–2010) and one year of (2010) data on surface meteorological elements (relative humidity, wind speed, air temperature), visibility and the concentrations of air pollutants (PM2.5, SO2, NO2 and O3) measured each hour of each day were analyzed using correlation analysis to investigate the main factors influencing haze in Hangzhou, China. The occurrence of hazy weather has become more frequent over the past eight years in Hangzhou, and haze appears about 160 days per year. The occurrence of haze during the day was more frequent in the spring and the winter and less frequent in the summer and the autumn. Low visibility occurred in the morning, and the maximum visibility occurred in the afternoon period. The results of the statistical analysis show that the relative humidity and the concentration of PM2.5 played the most important roles in reducing visibility. The correlation coefficients between the concentration of PM2.5 and the concentrations of O3, SO2 and NO2 indicate that O3 and NO2 are the dominant factors contributing to PM2.5 pollution, which, in turn, can lead to haze. To reduce the number of haze days, greater concern and more countermeasures should be taken to decrease the O3 and NO2 pollution in Hangzhou, China.

Correction Factor for Continuous Monitoring of Wood Smoke Fine Particulate Matter

Abstract: The US Environmental Protection Agency (EPA) has designated a handful of instruments as Federal Reference or Federal Equivalency Methods (FRM and FEM, respectively) for the monitoring of fine particulate matter (PM2.5). More commonly used for indoor exposure assessment studies are optical scanning devices such as the DustTrak (TSI) due to their portability and affordability. It is recommended by the manufacturer of these instruments that a “correction factor” be applied when assessing source-specific conditions. In this study, DustTraks were collocated with multiple samplers in various environments in an effort to establish an indoor, wood smoke-source specific correction factor. The DustTrak was found to report PM2.5 levels on average 1.6 times higher than a filter based method in two indoor sampling programs. The DustTrak also reported indoor PM2.5 concentrations 1.7 times higher than a FRM sampler during a regional forest fire event. These real-world scenarios give a correction factor within a reasonable range of the results of a controlled laboratory experiment in which DustTraks reported PM2.5 approximately 2 times higher than a FEM. Our indoor wood smoke-specific correction factor of 1.65 will allow for DustTraks to be confidently used in quantifying PM2.5 exposures within indoor environments predominantly impacted by wood smoke.

Chemical Characterization of Fine and Coarse Particles in Gosan, Korea during Springtime Dust Events

Abstract: Particulate matter was collected at Gosan, Korea, a remote location in the East China Sea, from late-March through May, 2007. Two sizes of particles, fine (PM2.5) and coarse (PM(subscript 10-2.5)) modes, were analyzed for chemical composition. Samples were analyzed by mass, elemental and organic carbon, and inorganic ions. Organic molecular markers were also measured using solvent-extraction gas chromatography mass spectrometry in order to identify different pollution sources. Two major dust events were captured, occurring on 31 March and 26 May, and were characterized by high concentrations of coarse particles, calcium, and secondary inorganic ions. A major pollution event occurred on 26 April with elevated fine particle concentrations and markers of combustion-related and secondary aerosols. Non-event periods in April and May were used to provide context in the interpretation of extreme events. This study demonstrates that carbonaceous aerosols from biomass burning, coal combustion, and motor vehicles containing organic and elemental components that are typically found in fine particles were included in coarse particle mass during dust events. Primary and secondary carbonaceous particles were found to become internally mixed with dust, which is expected to have implications on the dust’s chemical composition and surface properties.

Analysis of a severe dust storm event over China: Application of the WRF-Dust Model

Abstract: A severe dust storm (SDS) event occurred during March-20 to March-22, 2010 in China. A regional dynamical model coupled with a dust model (WRF-Dust) is used for analyzing this SDS event. The distribution of API (air pollution index) values in China and satellite (moderate-resolution imaging spectroradiometer—MODIS) AOD (aerosol optical depth) data are used to trace the dust storm and to compare with the model result. Several model sensitive studies are performed to analyze the roles of physical processes (such as dust source, transport, and deposition) in controlling the SDS event. The result suggests that the Gobi Desert is a major dust source of the SDS event. By contrast, the Taklamakan Desert plays minor roles for affecting the high dust concentrations in eastern/southern China during the SDS event. This study also suggests that a large amount of dust particles was deposited at the surface during the transport pathway between the Gobi Desert and eastern/southern China, and the high surface concentrations of dust particles can be considered as a new dust source region, which produced dust air pollution when surface winds were strong. In this study, we define this process as a propagate dust source (PDS). The calculation shows that the calculated dust concentrations were considerably lower than the measured values in the downwind regions of deserts when the PDS process was not included in the model. By including the PDS process, the calculated dust pollution in eastern and southern China is considerably improved. The further detailed analysis shows that the PDS played important roles in controlling the long-range transport of dust particles during the SDS event. This study suggests that this regional dust model (WRF-Dust) is a useful tool to analyze the important processes of dust storms that are often occurred in China.

Characteristics of Atmospheric Elemental Carbon (Char and Soot) in Ultrafine and Fine Particles in a Roadside Environment, Japan

Abstract: Atmospheric carbonaceous components, particularly char and soot in ultrafine particles (UFPs; Dp < 0.1 �� m) and fine particles (FPs; Dp < 2.5 �� m), were measured four times during one year in Saitama City, Japan, to observe the concentrations of elemental carbon (EC) and the relationship between the EC concentrations in UFPs and FPs, and to examine the possible emission sources of char and soot that constitute UFPs and FPs in a roadside environment. It was found that EC accounts for 33–37% of total carbon (TC) in FPs, whereas EC accounts for 12–20% of TC in UFPs. Both char-EC and soot-EC account for similar proportions of the total EC concentration in UFPs, while soot-EC accounts for only a small amount of the total EC in FPs. Positive and negative correlations between OC and soot-EC were observed for UFPs and FPs, respectively. The observed positive correlation in the case of UFPs possibly reflects the compactness (high density) of UFPs coated with condensed material, such as unburned fuel or lubricating oil emitted by motor vehicles, whereas the negative correlation in the case of FPs possibly indicates that whether or not the spaces between primary soot particles in FPs can be filled depends on the engine load of diesel vehicles operated near the sampling site. The positive and negative correlations were stronger for UFPs (r 2 = 0.69, n = 29, p < 0.001) and FPs (r 2 = –0.62, n = 29, p < 0.001) when the data collected at wind speeds greater than 2.5 m/s were excluded. The different morphological characteristics of the particles observed by transmission electron microscopy also support the observed correlations between OC and sootEC. The possible emission of char or char-like particles from motor vehicles was shown and discussed in this study.

Life Comes from the Air: A Short Review on Bioaerosol Control

Abstract: Air is filled with numerous tiny organisms, with sizes ranging from 50 nm to 10 μm. These organisms are called airborne biological particles or bioaerosols. In the human history of investigating the origin of life and fighting against contagious diseases, the recognition of bioaerosols and the development of control methods against them have played crucial roles. The pandemic outbreak of flu due to the influenza A H1N1 virus in 2009 and the bio-terror incidents in 2001 have alerted us to the importance of bioaerosol research. Here, control methods against bioaerosols are briefly reviewed, and suggestions are offered for future research on airborne biological particles.

Indoor and Outdoor Particle Number and Mass Concentrations in Athens. Sources, Sinks and Variability of Aerosol Parameters

Abstract: The scope of this work was to characterize PM mass and number concentration at typical residential microenvironments in the centre of Athens and to examine the relative contribution of the indoor and outdoor sources. Three residential flats located in densely populated residential areas were studied, during a warm and cold period of 2002. PM10, PM2 and black carbon (BC) mass concentrations, as well as ultrafine and accumulation mode particle number size distributions were recorded indoors and outdoors simultaneously. Outdoor concentrations of all size fractions were significant, and indicative of urban sites affected by heavy traffic. Indoor levels were generally lower than the corresponding outdoor ones. Nevertheless, elevated indoor concentrations were recorded, caused by increased ambient air penetration in the indoor microenvironments and/or indoor particle generation. The mean 24-hr indoor PM10 concentration at all residences was 35.0 ± 10.7 μg/m 3 during the warm period and 31.8 ± 7.8 μg/m 3 during the cold period. The corresponding PM2 concentration was 30.1 ± 11.1 μg/m 3 and 27.2 ± 3.6 μg/m 3 during warm and cold periods, respectively. Regression analysis of indoor and outdoor concentration data revealed that indoor BC may be considered mainly of outdoor origin. A large fraction of the outdoor-generated PM2 and ultrafine and accumulation mode particles also seems to penetrate indoors, causing elevated indoor levels. Regarding indoor particle generation, cooking was the strongest contributor in residential microenvironments.

Exposure to PM 10 , PM 2.5 , PM 1 and carbon monoxide on roads in Lahore, Pakistan

Abstract: Particulate matter pollution is one of the major environmental concerns in Pakistan. Over the past 20 years there has been a considerable increase in the number of motor vehicles. The present study was conducted to assess journey time and roadside exposure to particulate matter and carbon monoxide along major roads of Lahore during November, 2007. Measurements of particulate mass and carbon monoxide were carried out continuously inside an air conditioned vehicle, while commuting, and outside the vehicle at 36 different locations in the city. Additionally, monitoring was undertaken at a background site throughout the period. The overall mean journey-time concentrations of PM10, PM2.5, PM1, PM10–2.5 and CO were 103 �� g/m 3 , 50 �� g/m 3 , 38 �� g/m 3 , 53 �� g/m 3 and 8 ppm, respectively. At the roadside average PM10, PM2.5, PM1, PM10–2.5 and CO concentrations were 489 �� g/m 3 , 91 �� g/m 3 , 52 �� g/m 3 , 397 �� g/m 3 and 4 ppm, respectively. The highest levels were found at the sites with traffic congestion reflecting, not only, the large contribution of automobile exhaust but also the resuspension of road dust. The majority of public transport vehicles in Lahore are not air-conditioned and it is very likely that commuters are exposed to the similar high levels of pollution.

Chemical Characteristics of Particulate Matter during a Heavy Dust Episode in a Coastal City, Xiamen, 2010

Abstract: Xiamen, as a southeastern coastal city, is hardly affected by dust storms (DSs) sourced from the arid and semiarid areas in North or Northwestern China in spring. Unfortunately, during 21-23 March, 2010, the heaviest DS that had been recorded in past 50 years affected air quality seriously. Continuous particulate matter monitor was employed for the observation of PM2.5 (aerodynamic diameter less than 2.5 μm) and PM10 (aerodynamic diameter less than 10 μm) during 20-24 March 2010. Total suspended particulate (TSP) samples during this episode were also collected and their characteristics of element species and water-soluble ions were illustrated to characterize the heavy pollution in Xiamen. The DS peaked on 21 March, with the highest concentrations of 454.51 μg/m^3 and 990.24 μg/m^3 for PM2.5 and PM10, respectively. The variations of ratio for PM2.5/PM10 indicated that PM10 was the main particles that were influenced by DS. The higher ratios (DS/Non dust days) of Al, Fe, Mg, Mn, and Ba were over 5.0, which are primarily from a soil. However, the ratios of Zn, V, As, Ti, and Cr, mainly from anthropogenic sources, had a range of 1.3 to 3.4. These results suggested that the soil-sourced species made more contribution to DS particles compared to the anthropogenic species. The mass fractions of water-soluble ions in TSP indicated that the concentrations of K(superscript +), Ca(superscript 2+), Mg(superscript 2+), F(superscript -), NO2(superscript -), and NO3(superscript -) were evidently higher in DS samples than those of non-DS samples. The compositions of ions in dust aerosols showed that the multi-sources of aerosol were ubiquitous during the dust episode. The highest concentrations of sulfate and nitrate occurred in the day when dust ended in Xiamen, which demonstrated the formation of secondary pollutants from dust during the long-range transport, as well as from local environmental pollution.

Indoor PM2.5 Characteristics and CO Concentration Related to Water-Based and Oil-Based Cooking Emissions Using a Gas Stove

Abstract: Pollutant emissions from indoor cooking activities using clean fuels such as natural gas or LPG are strongly influenced by cooking ingredients and cooking methods In this study, we explore the characterization of indoor fine particles (PM25) and CO that are produced by two distinctive cooking methods: frying and boiling This characterization includes quantifying the presence of fine particles in a kitchen as well as in the adjoining room, analyzing size-segregated carbonaceous materials (EC and OC), and identifying variations in CO associated with the cooking method Four monitoring devices—a UCB particle monitor, an optical particle counter, a cascade impactor, and a CO monitor—were simultaneously used to measure temporal variations in mass concentrations of fine particles (PM25), particle number concentrations, their size distributions, and CO concentrations in the two rooms, respectively EC and OC analyses of the particles collected on a quartz filter by cascade impactor were conducted using the thermal optical method Frying produced higher emissions of fine particles with a wider range of aerodynamic sizes than boiling Particle spatial distribution was uniform across the rooms during boiling, because emissions were dominated by very fine particle size It was observed that particle mass size distributions with cut size ≤ 025 µm were predominant in all cooking methods CO concentration was lowest in tofu boiling and about one-tenth of the stove background level This is possibly due to the absorption of CO by steam cooking

Size Distribution of Airborne Particulate Matter and Associated Metallic Elements in an Urban Area of an Industrial City in Korea

Abstract: This study analyzed the size distribution of airborne particulate matter (PM) and 13 metallic elements associated with it. PM samples were collected using an eight-stage cascade impactor in a busy urban area of an industrial city, Korea during four seasons. Most of the fine and coarse particle mass was concentrated in the size range of 0.7–1.1 µm and 9–10 µm, respectively. PM mass showed two peaks in spring: The first peak was observed for the smallest particles (< 0.7 µm) and the second one was found in the coarse particles (2.1–10 µm). However, fine particles (0.7–2.1 µm) showed the highest PM concentrations in winter. In the distribution analysis of 13 metals in PM, three main groups were determined: (i) heavy metals (Cd, Zn, Mn, Ni and Cr) which were present in high concentrations in fine particles (< 2.1 µm) particularly at the size of 0.4–0.7 µm, (ii) light metals (Na, Ca, K, Al) and Fe which had high concentrations in coarse particles, and (iii) other heavy metals (Pb, Mg and Cu) showing high concentrations at sizes larger than 5.8 µm. The concentrations of Cd, Mn and Ni in the size range of 0.4–0.7 µm of the airborne particles and their total levels obtained by summing up the concentrations of the 8 classified size groups were exceeded the proposed thresholds or tolerance levels of the toxic heavy metals. The mass concentrations of Cd, Mn and Ni decreased with increasing particle size, except the size range of 9–10 µm, in PM10. The levels of Pb in PM10 did not show the size characteristics shown in Cd, Mn and Ni and also was below its tolerance level. Principal sources of 13 metallic elements in PM included natural sources and local anthropogenic sources such as non-ferrous metal smelting, oil combustion, welding, vehicular traffic and road dust.

Urban-scale Spatial-temporal Variability of Black Carbon and Winter Residential Wood Combustion Particles

Abstract: It has been suggested that certain organic aerosol components of wood smoke have enhanced ultraviolet absorption at 370 nm relative to 880 nm in two-wavelength aethalometer black carbon (BC) measurements. This enhanced absorption could serve as an indicator of wood combustion particles (“Delta-C” = UVBC370nm – BC880nm). From August 2009 to October 2010, week-long mobile monitoring campaigns were conducted during each season in Rochester, New York. The temporal and spatial variations of BC and Delta-C were investigated at twelve monitoring sites. A portable two-wavelength aethalometer housed in Clarkson’s Mobile Air Pollution Lab was used for data collection. The average BC concentrations were 0.94 µg/m 3 , 0.68 µg/m 3 , 0.47 µg/m 3 , and 0.81 µg/m 3 in summer, winter, spring, and fall, respectively. BC and DeltaC hotspots were identified. Coefficients of divergence (COD) and correlation coefficients (r) were calculated between site pairs to assess the spatial and temporal heterogeneity. High spatial divergence but uniform temporal variation in BC were found for these sites. Winter residential wood combustion (RWC) particles exhibited high spatial heterogeneity as well. In epidemiological studies, BC particles data from a central monitoring site are generally used as the basis in population exposure estimation. These results suggest that one central monitoring site may not adequately represent the actual BC and RWC particle exposure over a whole urban area.

Impact Assessment of Ambient Air Quality by Cement Industry: A Case Study in Jordan

Abstract: Cement industry is flourishing in the Middle East and North African countries due to the rapid population growth, the change in living style, and the availability of raw material in the region. Unless restricted regulations are enforced by local authorities to ensure compliance with national and international standards upon this industry, the increase of cement factories and their associated quarries in the region may deteriorate air quality and thus threaten the fragile ecosystems in the region. This paper presents predictions of air pollution (dust, SO2, NOx and CO) emitted from a modern cement plant that will be constructed in the Jordan Badia South-East of Amman. AERMOD is used to carry out the modeling part of this assessment. Our findings indicate that after the implementation of the proposed project, concentrations of air pollutant are found to be well below the permissible Jordanian Standards for ambient air quality. Therefore, the proposed activity is not likely to have any significant adverse impact on the air environment in the vicinity of the proposed project. However, The TSP concentration is expected to be high at the limestone quarry, which provides the factory with its main raw material, because it generates lots of dust as a result of rocks mining and crushing.

An Overview of Unipolar Charger Developments for Nanoparticle Charging

Abstract: Charging of nanoparticles is an important process in aerosol sizing. A unipolar charger is one of the most important upstream components in aerosol particle sizing and measurement systems by electrical mobility analysis. The aim of particle charging for an electrical mobility analyzer is to impose a known net charge distribution on the aerosol particles for each size. Charger performance depends on the extrinsic charging efficiency and stable operation. A well-designed unipolar charger should provide high extrinsic charging efficiency and stability that can be accurately determined for any given operating conditions. Depending on the mechanisms used to generate the ionized gas, the chargers can be classified into: (i) a corona discharge chargers, (ii) a radioactive chargers, and (iii) a photoelectric chargers. In this article, a brief overview on the development of existing unipolar aerosol chargers for nanoparticles is presented. Descriptions of the operating principles as well as detailed physical characteristics of these chargers, including the corona discharge, ionizing radiation, and photoelectron emission, are given.

Effect of Engine Load on Size and Number Distribution of Particulate Matter Emitted from a Direct Injection Compression Ignition Engine

Abstract: Particle size and number distribution from an engine tailpipe has a direct bearing on the residence time of the particles in the atmosphere and their toxicity. This study presents the number concentration and size distributions of nano-particles emitted from naturally aspirated, water cooled, single cylinder, diesel fuelled direct injection compression ignition (DICI) engine. The engine exhaust particle sizer (EEPS) was used for measurement of number, surface area and mass distributions of soot particles. It measures particle sizes ranging from 5.6 to 560 nm. Reading the size distribution 10 times per second allows for the measurement of transient emissions of soot particles. The experiments were conducted at a constant engine speed (1500 rpm) with varying engine load. It was found that (a) number and size distribution, (b) surface area and size distribution, and (c) mass and size distribution of soot particles varies significantly with the engine load. The width of the emitted particle size distribution increases with increasing engine load.

Application of Electrostatic Precipitator in Collection of Smoke Aerosol Particles from Wood Combustion

Abstract: A simple wire-plate electrostatic precipitator (ESP) was constructed in order to test the efficiency of collecting smoke particles from combustion of rubber-wood that is used as a source of biomass energy. The ESP contains a maximum of 15 collection plate electrodes and 20 wire electrodes per row between plates. The maximum input voltage of the Wheatstone bridge circuit using a high-voltage neon transformer was 13.5 kV (DC). The gap between plates and the distance between wires were adjustable. Results from the field test in a furnace indicate that the device could be used for a period of about one hour before cleaning the electrodes was required. The collection efficiency was decreased during the course of wood burning as the dust loading increased. Maximum efficiency was near 80% during the initial period. The distance between the collection plate electrodes had a greater influence on efficiency than the distance between the wire electrodes. The cleaning system used in this experiment was made from a row of PVC pipes to allow water to discharge radially to the plate electrodes on both sides. This system was equipped with the case of maximum collection efficiency that had a 50 mm gap between collection plate electrodes and a 64 mm distance between wire electrodes. Efficiency was increased after 120 minutes and maintained a collection efficiency of about 60%. This ESP is suitable for small and medium-sized enterprises (SMEs) to alleviate the release of detrimental chemicals such as PAHs into the atmosphere.

Chemical Composition of Water-soluble Ions and Carbonate Estimation in Spring Aerosol at a Semi-arid Site of Tongyu, China

Abstract: Fine aerosol samples (PM2.5) were collected daily at Tongyu, a semi-arid site in northeast China from April to June 2006, when Asian dust events occurred frequently. The concentrations of nine water-soluble ions were determined in the filter samples. The results showed that the mean mass level of PM2.5 at Tongyu station was 260.9 µg/m 3 , and the total mass concentration of the nine kinds of water-soluble ions occupied ~17% of the PM2.5 mass. Nine dust storm (DS) events were observed during the sampling period with mean concentrations of 528.0 μg/m 3 for PM2.5 and 39.5 μg/m 3 for total ions; during non-dust storm (NDS) periods, these values were 111.7 and 19.6 µg/m 3 , respectively. The mass concentrations of most of the water-soluble ions in the DS samples were much higher than those in the NDS samples. The ratios of ions to Fe were stable in DS samples, while they were more scattered in NDS samples, suggesting that the anthropogenic influence was significant in NDS samples collected at Tongyu. Moreover, the observed stable values of the K + /Fe, Ca 2+ /Fe, Na + /Fe, NO3 /Fe, and SO4 2/Fe ratios during the DS events should be associated with the ionic composition characteristics of soil dust in northeastern regions. Ion balance calculations for the NDS samples suggest that those aerosol particles were alkaline while DS samples were strongly alkaline. A deficit of measured anions during DS implies the presence of carbonate, which can be used to evaluate the carbonate concentration. A good relationship between the calculated and detected carbonate concentration was observed, which demonstrates that the ion balance supplies another method for estimating the carbonate content during DS.

Performance Evaluation of AERMOD and ADMS-Urban for Total Suspended Particulate Matter Concentrations in Megacity Delhi

Abstract: Regulatory models are useful tools for air quality management. However, application of models without proper evaluation may lead to erroneous conclusions and thus systematic model evaluation studies are essential prior to model application. Often, models are evaluated for a specific source and climatic condition and then find application to another source and climatic condition without this realization. In this context, two well known regulatory models namely; AERMOD (07026) and ADMS-Urban (2.2) are applied throughout the world in various countries without rigorous evaluation procedures. An attempt is made here to undertake performance evaluation of these models for a tropical city such as Delhi in India which is a well known megacity of the world. The models have been applied to estimate ambient particulate matter concentrations for the years 2000 and 2004 over seven sites in Delhi and model evaluation and inter-comparison is performed. Concentrations have been estimated for winter season in both years as the low temperature and low speed wind conditions in this season make it most significant from air pollution point of view. It has been found that though both the models have a tendency towards under-prediction, estimated values by both models agree with the observed concentrations within factor of two. However ADMS-Urban results show better trend correlation with observed values while bias between observed and estimated values is lower for AERMOD Results. The models include all the urban sources (ie. elevated point sources, vehicular traffic, domestic and other sources) in the city. The model validation is discussed in the light of emission inventory, requisite meteorological inputs and statistical performance measures. Performance evaluation of the above models is examined based on boundary layer parameterisations used in these models. Intercomparison of the model performances is envisaged to be useful for application to air quality management and further development of these models.

A CFD Simulation Study of VOC and Formaldehyde Indoor Air Pollution Dispersion in an Apartment as Part of an Indoor Pollution Management Plan

Abstract: This paper is a preliminary report of an indoor pollution case study in a complex of apartments as a part of an Indoor Pollution Management Plan (IPMP). It describes the calculation by Computational Fluid Dynamics (CFD) techniques and presents the predicted air flow, Volatile Organic Compounds (VOCs) and formaldehyde contaminant distributions in an apartment comprised of a full-scale kitchen with open access to a living room, ventilated by an exhaust hood. The CFD Code PHOENICS®, which is based on solving the full 3-D Navier Stokes equations for turbulent flow and scalar conservation equations, was used. Major kitchen indoor pollution sources, VOCs and formaldehyde emitting materials and their emission characteristics were calculated through the use of emission factors. A typical apartment was used under case study and its detailed geometry was applied for the CFD model. To analyze the characteristics of the indoor environment, different mixing ventilation schemes (different locations of the cooker/oven and air inlets) were chosen as the parameters to investigate the indoor environment. The fields of VOCs and formaldehyde for several air inlets window positions, and ventilation parameters were calculated and compared. It was concluded that CFD methods can be used as a useful tool to assist the rational design of indoor spaces.

Air Pollution in Residential Areas from Wood-fired Heating

Abstract: An important source of inhalable particles in residential areas, particularly in the winter season, is the biomass combustion when wood is used for domestic heating. This is a continuation of our previous investigation about wood smoke pollution in residential areas of southern Germany (Bari et al., 2009). The target of this study was to characterize ambient levels of criteria pollutants, their risk assessment and find out influence of hardwood combustion on local air quality. Particle-phase PM(subscript 10) samples were collected at a residential site Dettenhausen near Stuttgart during 2005/06 and winter 2009. Samples were analysed by gas chromatography-mass spectrometry for polycyclic aromatic hydrocarbons (PAHs) and other wood smoke tracer compounds (e.g., levoglucosan, methoxyphenols). High concentrations of PM(subscript 10) and total PAHs were found during winter 2009 like winter 2005/06. Carcinogenic PAHs were detected in high concentrations and contributed 44% of the total PAHs in the ambient air. The significant concentrations of hardwood markers (i.e., syringaldehyde, acetosyringone) found in the ambient air suggest that the influence of hardwood combustion on ambient air quality is significant. Based on the emission ratio of hardwood markers and PM(subscript 10), it can be concluded that in the investigated residential site about 57% of ambient PM(subscript 10) pollution can be attributed to hardwood combustion for winter heating.

Quantitative Source Apportionment of Size-segregated Particulate Matter at Urbanized Local Site in Korea

Abstract: Cl - , NO3 - , SO4 2- ) were analyzed by ion coupled plasma atomic emission spectrometry and ion chromatography after proper pretreatments of each sample filter. Based on the chemical information, positive matrix factorization (PMF) was used to identify size-segregated PM sources except for ST9. A total of 11 sources were identified and their contributions were intensively estimated. Further conditional probability function (CPF) was used to examine the potential location of identified sources after PMF modeling, A result of 2-year average source contribution showed that aged sea salt, road dust, long-range transport, and soil sources were most dominant in ST1 (PM > 9.0 μm); mixed automobiles and coal combustion sources in ST5 (2.1 μm < PM < 3.3 μm); oil combustion, secondary aerosol, and incineration in ST8 (0.4 μm < PM < 0.7 μm); and biomass burning source in ST7 (0.7 μm < PM < 1.1 μm), respectively. The relative contribution of most abundant sources was 32.4% of long- range transport source in the coarse particle mode and 34.5% of secondary aerosol in the fine particle mode, respectively. It seems that the size-resolved analysis by PMF provides useful information on controlling local/regional emission sources and on acquiring scientific knowledge for size-resolved aerosol compositions emitted from specific sources.

Emissions of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans from an Electric Arc Furnace, Secondary Aluminum Smelter, Crematory and Joss Paper Incinerators

Abstract: Emissions of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) from the stack flue gases, fly ashes and bottom ashes of various stationary sources were investigated. The mean total PCDD/F I-TEQ concentration of flue gas ranged from 0.00681 to 0.703 ng I-TEQ/Nm 3 . However, the emission factor of PCDD/F from various incinerators was 0.00827 to 3.50 µg I-TEQ/ton, whereas it was 5.36 µg I-TEQ/body for a crematory (CM). In addition, the mean total PCDD/F I-TEQ content in fly ash from an electric arc furnace (EAF) and a secondary aluminium smelter (secondary ALS) were 74.0, and 49.9 ng I-TEQ/kg, respectively, whereas they are 21.3 and 0.494 ng I-TEQ/kg for bottom ash. Meanwhile, the removal efficiency of PCDD/F by bag filters from EAF was –44.4% which is attributed to the “memory effect”. The indicatory PCDD/Fs of EAF, and secondary ALS have the same congeners (1,2,3,7,8,9-HxCDF, 2,3,7,8-TeCDF, and 1,2,3,7,8-PeCDF). In addition, CM, joss paper-A (JP-A) and joss paper-B (JP-B) incinerators have similar indicatory PCDD/F (2,3,4,6,7,8-HxCDF, OCDF, 1,2,3,4,6,7,8-HpCDD, and OCDD). The high contribution of total PCDD/F is from fly ash (61.1-95.3%) for metallurgical facilities (EAF, secondary ALS), whereas 99.9% contribution of stack flue gas is from JP-A and JP-B. In conclusion, continually monitoring various PCDD/F emission sources is necessary to understand current PCDD/F emission (flue gas, fly/bottom ash) and the related removal efficiency of existing air pollution control devices. Information about both emission factors of PCDD/Fs and indicatory PCDD/F congeners are useful for the establishment of control strategies and for use as fingerprints with regard to the dominant congeners from different emission sources.

Contributions of Biogenic and Anthropogenic Hydrocarbons to Secondary Organic Aerosol during 2006 in Research Triangle Park, NC

Abstract: A recently developed, organic tracer-based method was used to estimate the secondary contributions of biogenic and anthropogenic precursor hydrocarbons to ambient organic carbon concentrations in PM2.5 during 2006 in Research Triangle Park, North Carolina, USA. Forty-six ambient PM2.5 samples were collected on a one in six schedule and analyzed for (1) secondary organic aerosol tracer compounds, and (2) levoglucosan, a compound used as a tracer for biomass burning. For isoprene, α-pinene, β-caryophyllene, and toluene, the secondary contributions to ambient organic carbon concentrations (OC) were estimated using measured tracer concentrations and previously established, laboratory-determined mass fractions. The estimates show secondary formation from these four hydrocarbons contributes up to 55% of the ambient organic carbon concentrations (Julian day 197) when OC was 5.98 μg C/m^3. The relative contributions are highly temperature dependent; estimates of particulate carbon from isoprene and α-pinene precursors peaked during the warmest days, and represented up to 40% and 10% of the measured OC, respectively (Julian days 197 and 191). Conversely, biomass burning represented up to 21% of the organic carbon concentrations on the coldest day sampled, Julian day 329, while contributions of secondary organic carbon from these four precursor hydrocarbons remained low at 4% of the measured 2.55 μg C/m^3 OC.

Physicochemical Properties of PM2.5 and PM2.5-10 at Inland and Offshore Sites over Southeastern Coastal Region of Taiwan Strait

Abstract: This study investigates the effects of sea-land breezes (SLBs) and northeastern monsoon (NEM) on the physicochemical properties of particulate matter (PM) in the atmosphere over southeastern coastal region of Taiwan Strait. The intensive PM sampling protocol was consecutively conducted for forty-eight hours. During the sampling periods, PM2.5 and PM2.5–10 were simultaneously measured with dichotomous samplers at four sites (two inland and two at offshore sites) and PM10 was measured with beta-ray monitors at these same four sites. Strong SLBs were regularly observed in the coastal region of southern Taiwan during the SLBs periods, while significant northeastern monsoons appeared during the NEM periods. The mass ratios of PM2.5/PM10 during the NEM periods were always higher than the SLBs periods. The most abundant ionic species of PM were SO4 2- , NO3 - , and NH4 + . The most common chemical compounds of PM in southern Taiwan were ammonium sulfate ((NH4)2SO4) and ammonium nitrate (NH4NO3). Carbon contents of PM during the NEM periods were higher than during the SLBs periods. The organic-to-elemental-carbon ratio (OC/EC) of PM2.5 ranged from 1.05 to 4.39 with an average of 2.26. The order of major metallic elements of PM2.5 in the SLBs and NEM periods is Fe > Ca > K > Al > Mg > Zn > Pb and Ca > Fe > Al > K > Mg > V > Ni, respectively, and of PM2.5–10 is Ca > K > Al > Fe > Mg > Zn and Fe > Ca > Al > K > Mg > V > Ni, respectively. This study reveals that the accumulation of PM offshore, due to land breezes, influences the tempospatial distribution of PM at the coastal region in southern Taiwan. Moreover, the nss-[SO4 2]/[Na + ] ratio regarded as a PM pollution index, is more suitable than the [NO3 ]/[Na + ] ratio.

Chemical composition of indoor and outdoor atmospheric particles at emperor Qin's Terra-cotta museum, Xi'an, China

Abstract: Indoor particles and microclimate were measured in summer (August 2004) and winter (January 2005) periods inside and outside Emperor Qin's Terra-Cotta Museum in Xi’an, China. Indoor temperature ranged from 21.9°C to 32.4°C in summer and from 0°C to 5.3°C in winter. Relative humidity varied from 56% to 80% in summer and from 48% to 78% in winter. The number concentrations of particles were lower (0.3–1.0 μm) in summer, and were higher (1.0–7.0 μm) in winter. The average indoor PM2.5 and TSP concentrations were 108.4 ± 30.3 μg/m 3 and 172.4 ± 46.5 μg/m 3 in summer and were 242.3 ± 189.0 μg/m 3 and 312.5 ± 112.8 μg/m 3 in winter, respectively. Sulfate, organic matter, and geological material dominated indoor PM2.5, followed by ammonium, nitrate, and elemental carbon. Several milligram of sulfate particles can deposited in the museum per square meter each year based on the dry deposition estimate. High concentrations of acidic particles suspended inside the museum and their depositions have high risk for the erosion of the terra-cotta figures.