Stationary Emission Sources Research Articles

Particle associated polycyclic aromatic hydrocarbons in the atmospheric environment of urban and suburban residential area

Ten polycyclic aromatic hydrocarbons associated with suspended particulate matter in the ambient air were collected at two sampling sites: urban and suburban residential areas of Yokohama, Japan from 1999 to 2005. The concentrations of target compounds were determined using gas chromatography-mass spectrometry. The total concentrations were higher in urban residential area than suburban residential area. They ranged from 0.31 to 6.16 ng/m3 withameanof2.07ng/m3 and 0.33 to2.87ng/m3 with a mean of 1.02 ng/m3 in the urban and suburban residential areas, respectively. The predominant compounds determined both in the urban and suburban residential areas were benzo[b]fluoranthene, benzo[ghi]perylene, indeno[1,2,3-cd]pyrene and benzo[e]pyrene. The concentrations of 5- and 6-ring polycyclic aromatic hydrocarbons were higher in the urban than the suburban residential area, accounting for 77.3 % and 72.1 % of total polycyclic aromatic hydrocarbons, respectively. Source identification was performed by principal component analysis. Two principal components were identified for each study area and these accounted for 95.9 % and 83.3 % of total variance, respectively. The results revealed that stationary source and vehicle emissions were the major pollution sources in the studied areas. The impact of emission regulations for automobiles in large Japanese cities, which were enacted during 2002 and 2003, was also studied. Based on the average total concentration, emission reduction was 47.8 % and 18.6 % in urban residential and suburban residential areas, respectively.

Financing new power plants ‘CCS Ready’ in China–A case study of Shenzhen city

Abstract We evaluate the benefits of a ‘CCS Ready Hub’ approach, a regional ‘CCS Ready’ strategy, which not only includes a number of new coal-fired power plants but also integrates other existing stationary CO2 emissions sources, potential storage sites and potential transportation opportunities into an overarching simulation model. A dynamic top-down simulation model was built based on economic decision criteria and option pricing theory. The model inputs and assumptions build on spatial sampling and analysis using a geographic information system (GIS) approach, engineering assessment of local projects and outputs of a CCS retrofitting investment evaluation through cost cash flow modelling. A case study of Shenzhen city in the Pearl River Delta area in Guangdong in southern China is presented, based on engineering and cost assessment studies and stakeholder consultations and building on existing geological surveys and infrastructure plans. The simulation results show that financing ‘CCS Ready’ at regional planning level rather than only at the design stage of the individual plant (or project) is preferred since it reduces the overall cost of building integrated CCS systems. On the other hand, we found the value of considering existing stationary CO2 emissions sources in CCS ready design. Therefore, we recommended that making new plants CCS ready or planning a CCS ready hub should consider existing large emissions sources when possible.

Preliminary assessment of CO2 geological storage potential in Chongqing, China

This paper presents a preliminary assessment of the potential for CO2 geological storage in Chongqing, China. Currently, there are about 116 large stationary CO2 point emission sources which emit 85.57 MtCO2/yr totally. These stationary sources are mainly belonged to four industries: cement, power plant, iron & steel and synthetic ammonia industries. In the three kinds of geological storage formations, namely, deep saline formations (DSFs), unmineable coalbeds and depleted gas fields, the total basin-scale theoretical storage capacities of CO2 reach 24.36 Gt, equivalent to about 285 times of the annual total CO2 emissions in Chongqing. The DSFs have the largest potential storage capacity accounting for 98% of the total storage capacities. The matching results between CO2 point emission sources and candidate geological storage formations show that 94.8% of the point emission sources (accounting for 97.1% of annual total emissions) can find at least one candidate geological storage formation in its adjacent areas. This means that, for Chongqing, the CO2 transport cost is likely very low. The research findings indicate that there is great potential for CO2 geological storage technology to deploy in Chongqing and for this technology to deliver profound and sustaining impacts on reducing CO2 emissions and developing low-carbon economy in Chongqing. This preliminary study is expected to stimulate more researches, critical thinking and policy actions to promote positive measures to reduce greenhouse gas emissions so as to mitigate the impact of global climate change, as well as to set a good example for other regions in China.

Control of Diesel Gaseous and Particulate Emissions with a Tube-Type Wet Electrostatic Precipitator

Abstract In this study, experiments were performed with a bench-scale tube-type wet electrostatic precipitator (wESPs) to investigate its effectiveness for the removal of mass- and number-based diesel particulate matter (DPM), hydrocarbons (HCs), carbon monoxide (CO), and oxides of nitrogen (NOx) from diesel exhaust emissions. The concentration of ozone (O3) present in the exhaust that underwent a nonthermal plasma treatment process inside the wESP was also measured. A nonroad diesel generator operating at varying load conditions was used as a stationary diesel emission source. The DPM mass analysis was conducted by means of isokinetic sampling and the DPM mass concentration was determined by a gravimetric method. An electrical low-pressure impactor (ELPI) was used to quantify the DPM number concentration. The HC compounds, n-alkanes, and polycyclic aromatic hydrocarbons (PAHs) were collected on a moisture-free quartz filter together with a PUF/XAD/PUF cartridge and extracted in dichloromethane with sonication. Gas chromatography (GC)/mass spectroscopy (MS) was used to determine HC concentrations in the extracted solution. A calibrated gas combustion analyzer (Testo 350) and an O3 analyzer were used for quantifying the inlet and outlet concentrations of CO and NOx (nitric oxide [NO] + nitrogen dioxide [NO2]), and O3 in the diesel exhaust stream. The wESP was capable of removing approximately 67–86% of mass- and number-based DPM at a 100% exhaust volumetric flow rate generated from 0- to 75-kW engine loads. At 75-kW engine load, increasing gas residence time from approximately 0.1 to 0.4 sec led to a significant increase of DPM removal efficiency from approximately 67 to more than 90%. The removal of n-alkanes, 16 PAHs, and CO in the wESP ranged from 31 to 57% and 5 to 38%, respectively. The use of the wESP did not significantly affect NOx concentration in diesel exhaust. The O3 concentration in diesel exhaust was measured to be less than 1 ppm. The main mechanisms responsible for the removal of these pollutants from diesel exhaust are discussed.

Control of Diesel Gaseous and Particulate Emissions with a Tube-Type Wet Electrostatic Precipitator

In this study, experiments were performed with a bench-scale tube-type wet electrostatic precipitator (wESPs) to investigate its effectiveness for the removal of mass- and number-based diesel particulate matter (DPM), hydrocarbons (HCs), carbon monoxide (CO), and oxides of nitrogen (NOx) from diesel exhaust emissions. The concentration of ozone (O3) present in the exhaust that underwent a nonthermal plasma treatment process inside the wESP was also measured. A nonroad diesel generator operating at varying load conditions was used as a stationary diesel emission source. The DPM mass analysis was conducted by means of isokinetic sampling and the DPM mass concentration was determined by a gravimetric method. An electrical low-pressure impactor (ELPI) was used to quantify the DPM number concentration. The HC compounds, n-alkanes, and polycyclic aromatic hydrocarbons (PAHs) were collected on a moisture-free quartz filter together with a PUF/XAD/PUF cartridge and extracted in dichloromethane with sonication. Gas chromatography (GC)/mass spectroscopy (MS) was used to determine HC concentrations in the extracted solution. A calibrated gas combustion analyzer (Testo 350) and an O3 analyzer were used for quantifying the inlet and outlet concentrations of CO and NOx (nitric oxide [NO] + nitrogen dioxide [NO2]), and O3 in the diesel exhaust stream. The wESP was capable of removing approximately 67–86% of mass- and number-based DPM at a 100% exhaust volumetric flow rate generated from 0- to 75-kW engine loads. At 75-kW engine load, increasing gas residence time from approximately 0.1 to 0.4 sec led to a significant increase of DPM removal efficiency from approximately 67 to more than 90%. The removal of n-alkanes, 16 PAHs, and CO in the wESP ranged from 31 to 57% and 5 to 38%, respectively. The use of the wESP did not significantly affect NOx concentration in diesel exhaust. The O3 concentration in diesel exhaust was measured to be less than 1 ppm. The main mechanisms responsible for the removal of these pollutants from diesel exhaust are discussed.

Weekday/weekend differences in ambient aerosol level and chemical characteristics of water-soluble components in the city centre

Weekday and weekend ambient aerosol samples were collected from the city centre of Cairo, namely “Ramsis” during the summer season of the year 2006, and have been analyzed for water-soluble ionic species. The average concentrations of the total suspended particulate matter (TSP) and their water-soluble components were higher during weekdays than on weekends, indicating that the decreased traffic density on weekends leads to a decrease in the levels of the TSP and their water-soluble ionic species. The average concentrations of the TSP were 454 μg m −3 on weekdays and 298 μg m −3 on weekends. The weekday/weekend concentration ratios were 1.52 for TSP, 1.27 for SO 4 2−, 1.64 for Cl −, 1.54 for NO 3 −, 1.17 for NH 4 +, 1.67 for Ca 2+, 1.83 for Na +, 1.75 for K + and 1.73 for Mg 2+. City centre of Cairo has high levels of the TSP and their water-soluble ionic species compared with many polluted cities in the world. Among all of the measured water-soluble components, SO 4 2− was the most abundant species followed by Ca 2+ on weekdays and weekends. The average mass ratios of NO 3 −/SO 4 2− in the TSP were 0.41 on weekdays and 0.34 on weekends, suggesting that the stationary source emissions were more predominant. The NH 4 +/SO 4 2− molar ratios and its relation with the concentrations of TSP and Ca 2+ during the weekdays and weekends indicate that the chemical form of sulfate and ammonium in aerosol particles varies with TSP and Ca 2+ levels. At high TSP and Ca 2+ levels, and NH 4 +/SO 4 2− molar ratios less than one, SO 4 2− in aerosol particles may be present as CaSO 4 and (NH 4) 2SO 4·CaSO 4·2H 2O, whereas it is expected to be present as (NH 4) 2SO 4, (NH 4) 2SO 4·CaSO 4·2H 2O and CaSO 4 at low levels of TSP and Ca 2+, and NH 4 +/SO 4 2− molar ratios between 1 and 2. The mean pH values of the TSP were 7.65 on weekdays and 6.97 on weekends, indicating that aerosol particles brought a large amount of crustal species, and might alleviate the tendency of acidification. The relationships between the concentrations of acidic components (NO 3 − and SO 4 2−) and basic components (NH 4 +, Ca 2+ and Mg 2+) on weekdays and weekends indicate that the acidity of aerosol particles is neutralized. Ca 2+ and NH 4 + are the most dominant neutralization substances in Cairo atmosphere.

울산 지역에서 2001년 이후 이산화황(SO2)의 고농도 사례 분석과 저감 정책 방안의 검토

Until comparatively lately, the annual time series of the <TEX>$SO_2$</TEX> concentration had been shown in a decreasing trend in Ulsan as well as other Korean cities. However, the high concentration of <TEX>$SO_2$</TEX> was frequently found in the specific countermeasure region including the national industrial complex such as Mipo and Onsan in the Ulsan city for the period of <TEX>$2001{\sim}2004$</TEX>. There are many conditions that can influence the high concentration of <TEX>$SO_2$</TEX> at monitoring sites in Ulsan, such as: First, annual usage of the fuel including sulfur increased in comparison with the year before in spite of the fuel conversion policy which wants to use low sulfur oil less than 3% and LNG. Second, point source, such as the power plants and the petroleum and chemistry stacks, was the biggest contributor in <TEX>$SO_2$</TEX> emission, as a analyzed result of both the air quality modeling and the stack tole-monitoring system (TMS) data. And third, the air pollutants that occurred in processes of homing and manufacturing of the fuel including sulfur were transported slow into a special monitoring site by accumulating along the frontal area of see-breeze. It was concluded that Ulsan's current environmental policy together with control methods should be changed into the regulation on total amount of emission, including a market-based emission trading with calculating of atmospheric environmental critical loads, for the <TEX>$SO_2$</TEX> reduction like the specific countermeasure for the <TEX>$O_3$</TEX> and PM10 reduction in the Seoul metropolitan area. And this change should be started in the big point sources of <TEX>$1{\sim}3$</TEX> species because they are big contributors of Ulsan's <TEX>$SO_2$</TEX> pollution. Especially it is necessary to revitalize of the self-regulation environmental management. Other control methods for sustaining the <TEX>$SO_2$</TEX> reduction are as follows: maintenance of the fuel conversion policy, reinforcement of the regional stationary source emission standard, and enlargement of the stack TMS.

Phase change of catalysts derived from a LDH-deoxycholate intercalated compound and its impacts on NO reduction from stationary source emissions

Deoxycholate and keggin-type polyoxometalate (PW12O40 and SiW12O40) pillared-hydrotalcite-type clay catalysts were prepared, and the effects of calcination temperature were studied on selective catalytic reduction of NO by NH3 over excess oxygen in the reaction temperature range 150–450°C. The results showed that over 99% N2/N2O selectivity was achieved at all testing temperatures for all pillared-clay catalysts. The activity of all pillared-clay catalysts increased significantly with temperature beyond 300°C. It was found that all pillared clays had different thermal transition behaviors at various stages of calcinations temperature, which affected the SCR activity. The dehydroxylated intermediates and amorphous mixed oxide forms, whose Brønsted acid sites were still preserved after calcinations, appeared to yield high NO conversion with high N2/N2O selectivity. Generally, the PW12-clay-derived catalysts seem to have the highest activity. Five percent Fe loading by impregnation method significantly increased activity of pillared-clay catalysts while high N2/N2O selectivity was maintained. Fe-loaded catalysts also showed obviously higher N2/N2O selectivity than the commercial catalyst; 4.4% V2O5–8.2% WO3/TiO2.

Approaches adopted to assess environmental impacts of PCDD/F emissions from a municipal solid waste incinerator

Different approaches were carried out in this work to assess environmental impacts of a municipal solid waste incinerator. A total of seven sites in the vicinity of the facility were chosen to collect air, banyan leaf and soil samples for analyses of PCDD/Fs by high-resolution gas chromatography/high-resolution mass spectrometry. Based on the PCDD/F concentrations of the three matrices determined at sites upwind, downwind and area of maximum ground concentration, it was found that the environmental impact of the MSWI was not obvious. PCDD/F concentration isopleths of the three environmental compartments coupled with wind rose of the region proved that the influence of the MSWI on the environment was also rather limited. It clarified emission sources by confirming that the PCDD/F concentrations originated mostly from the existing stationary emission sources in the vicinity. Through principal component and cluster analyses on congener profiles, the influence of metallurgical facilities and medical waste incinerators on the ambient air was assessed. Moreover, the modeling of ISCST3 demonstrated also that the contribution of the MSWI to ambient atmospheric PCDD/Fs was minimal. The approaches studied have led to identical conclusions, and thus are useful to cross-evaluate the environmental impact of an MSWI.

Removal of diesel particulate matter (DPM) in a tubular wet electrostatic precipitator

In this study, experiments were performed with a tubular wet electrostatic precipitator (wESP) to evaluate its effectiveness for the removal of mass- and number-based DPM emissions. A nonroad diesel generator utilizing a low sulfur diesel fuel (500 ppm w) operating under varying load conditions was used as a stationary DPM emission source. The US EPA Method 5 “Sampling Method for Stationary Sources” and Method 1A “Sampling and Velocity Traverses for Stationary Sources with Small Stacks or Ducts” were adopted as reference methods for measurement of DPM mass concentration. An electrical low-pressure impactor (ELPI) was used to quantify the DPM number concentration in the diluted exhaust gas at each tested condition. The wESP was evaluated with respect to varying engine loads and to different operational control parameters, such as corona power and gas residence time, to determine their effect on overall removal efficiency. The results show that the removal efficiency of the wESP increased as the engine loads decreased principally due to an increase in gas residence time and a decrease in DPM concentrations. At a constant wESP voltage and engine load, the increase of gas residence time within the wESP led to a significant increase in total DPM removal efficiency. In addition, total DPM removal efficiency was found to be directly related to the corona power, with increasing removal efficiency measured for increases in corona power. The linear correlation of DPM effective migration velocity and superficial gas velocity was established and an empirical equation is given. The wESP appears to be a promising alternative method for control of mass-based as well as number-based DPM emissions.

MINERAL CARBONATION AS A POTENTIAL CARBON DIOXIDE STORAGE OPTION FOR THE REGION OF WESTERN MACEDONIA, GREECE

The long-term storage of the greenhouse gas C02 generated by fossil fuel-fired power plants in the form of stable mineral carbonates appears to be a promising option for reducing global CO2 emissions. In the case of mineral carbonation captured gaseous CO2 is chemically stored in an exothermic reaction by the carbonation of magnesium or calcium silicate minerals, forming environmentally benign and thermodynamically stable products. The purpose of this paper is to give an overview of the carbon dioxide storage by mineral carbonation and to examine the feasibility of this sequestration option in the region of Western Macedonia. The main candidate minerals for carbonation and their sequestration capacity are presented. Furthermore, the most promising mineral carbonation process routes as well as the thermodynamics and kinetics of carbonation reaction are addressed, based on a review on the published literature. In Greece abundant magnesium-rich ultramafic rocks exist that probably could support the national CO2 emissions abatement policy. The attractiveness stems from the favourable geographical relationship between large stationary CO2 emission sources and potential magnesium silicate deposits. Thus, a roughly description of the olivine deposits and their quality in the region of Western Macedonia will be provided

Validation of Three New Methods for Determination of Metal Emissions Using a Modified Environmental Protection Agency Method 301

Three new methods applicable to the determination of hazardous metal concentrations in stationary source emissions were developed and evaluated for use in U.S. Environmental Protection Agency (EPA) compliance applications. Two of the three independent methods, a continuous emissions monitor-based method (Xact) and an X-ray-based filter method (XFM), are used to measure metal emissions. The third method involves a quantitative aerosol generator (QAG), which produces a reference aerosol used to evaluate the measurement methods. A modification of EPA Method 301 was used to validate the three methods for As, Cd, Cr, Pb, and Hg, representing three hazardous waste combustor Maximum Achievable Control Technology (MACT) metal categories (low volatile, semivolatile, and volatile). The modified procedure tested the methods using more stringent criteria than EPA Method 301; these criteria included accuracy, precision, and linearity. The aerosol generation method was evaluated in the laboratory by comparing actual with theoretical aerosol concentrations. The measurement methods were evaluated at a hazardous waste combustor (HWC) by comparing measured with reference aerosol concentrations. The QAG, Xact, and XFM met the modified Method 301 validation criteria. All three of the methods demonstrated precisions and accuracies on the order of 5%. In addition, correlation coefficients for each method were on the order of 0.99, confirming the methods’ linear response and high precision over a wide range of concentrations. The measurement methods should be applicable to emissions from a wide range of sources, and the reference aerosol generator should be applicable to additional analytes. EPA recently approved an alternative monitoring petition for an HWC at Eli Lilly’s Tippecanoe site in Lafayette, IN, in which the Xact is used for demonstrating compliance with the HWC MACT metal emissions (low volatile, semivolatile, and volatile). The QAG reference aerosol generator was approved as a method for providing a quantitative reference aerosol, which is required for certification and continuing quality assurance of the Xact.

Site-specific health risk assessment of dioxins and furans in an industrial region with numerous emission sources

While the sources of releasing dioxins have received much attention, the health risks of incinerators are studied considerably more than those of other sources, such as metallurgical industry. Furthermore, risk assessments focus primarily on the effects of single sources; few have addressed the aggregate risks from multiple sources in a region. When many sources of dioxins exist in an area, such as the Industrial Park located in the densely populated district—Siaogang District in southern Taiwan where 17 primary known PCDD/F stationary emission sources are clustered, is the aggregate exposure to these sources imposing high risks even though individual sources comply with emission standards? The study combined the multimedia and multiple pathway exposure modeling and site-specific exposure scenario to assess dioxin risks contributed by the 17 emission sources in the District, including municipal waste incinerators, medical waste incinerators, sinter plants, electric arc furnace, secondary aluminum smelters, cement kilns, etc. The average cancer risk of a resident living in the District was found to be 3.43E−04 under the site-specific exposure scenario. The top emission source is the sinter plant, followed by the electric arc furnace. The information has driven the local government to conduct more complete assessment and at the same time to consider enforcing a stricter local standard of dioxin emissions in the Siaogang District.

Health Impact of Road Traffic Emissions, Forecasted Decrease Associated to Implementation of European Standards in French Vehicle Fleet

SAB4-PD-01 Session Title: Air Pollution: Mechanisms and Health Introduction: Health Impact Assessment (HIA) of road transports emissions, based on exposure response functions (ERF) from epidemiologic studies, have influenced new European standards for terrestrial vehicles emissions. This study aims at quantifying the health impact decrease attributable to European Standards Implementation in France between 2000 and 2010. Methods: Urban exposure to road traffic emissions (RTE) was evaluated with data from French air quality-monitoring network during the year 2000. The concentrations in NO2 and PM10 were estimated by a geostatistic approach in grid cells of 4 km. Modelling the emissions of stationary and mobile sources refined this approach. The second approach allows estimating the contribution ratio of RTE in the total atmospheric concentrations. The population data in each cell and stratified by age were extracted from the 1999 French census. HIA method followed the WHO and InVS methodologic recommendations. Health impacts (HI) were estimated with European epidemiologic ERF derived for elderly, adults, and children. For children, new health outcomes such as preterm birth or childhood cancers were included. The morbidity and mortality rates for the general population came from French sanitary statistics. Comparison of the results between 2000 and 2010 made it possible to quantify the reduction associated with the introduction of new standards of emission. Results: In urban area, mean ambient concentration (all sources) should have decreased by 27% for NO2 and 28% for PM10 during the 2000 to 2010 period. However, RTE contribution rates will follow a lower decreasing trend for both pollutants (respectively 18%, 20%). In 2000, main HI due to RTE are long-term mortality (7700 cases per year), cardiovascular hospitalization (10,600), and short-term mortality in adults (3600). In children, majors HI are bronchitis (258,000), asthma attacks (47,200), and premature birth (11,765). Contribution of RTE to HI results will decrease in 2010 by 17% to 49% according to health outcomes. Conclusions: Major uncertainties, except those in the exposure assessment, come under ERF used for children. Evidence of causality between certain health effects and the air pollution has not yet been strongly shown. ERF for childhood cancer and preterm birth are based on a single epidemiologic study. Moreover, we were unable to take demographic and population health evolutions into account. HIA results plead for accompanying actions on traffic flux that will increase emissions standard benefits for population health.

Collection of Ultrafine Diesel Particulate Matter (DPM) in Cylindrical Single-Stage Wet Electrostatic Precipitators

Long-term exposures to diesel particulate matter (DPM) emissions are linked to increasing adverse human health effects due to the potential association of DPM with carcinogenicity. Current diesel vehicular particulate emission regulations are based solely upon total mass concentration, albeit it is the submicrometer particles that are highly respirable and the most detrimental to human health. In this study, experiments were performed with a tubular single-stage wet electrostatic precipitator (wESP) to evaluate its performance for the removal of number-based DPM emissions. A nonroad diesel generator utilizing a low sulfur diesel fuel (500 ppmw) operating under varying load conditions was used as a stationary DPM emission source. An electrical low-pressure impactor (ELPI) was used to quantify the number concentration distributions of diesel particles in the diluted exhaust gas at each tested condition. The wESP was evaluated with respect to different operational control parameters such as applied voltage, gas residence time, etc., to determine their effect on overall collection efficiency, as well as particle size dependent collection efficiency. The results show that the total DPM number concentrations in the untreated diesel exhaust are in the magnitude of approximately108/cm(3) at all engine loads with the particle diameter modes between 20 and 40 nm. The measured collection efficiency of the wESP operating at 70 kV based on total particle numbers was 86% at 0 kW engine load and the efficiency decreased to 67% at 75 kW due to a decrease in gas residence time and an increase in particle concentrations. At a constant wESP voltage of 70 kV and at 75 kW engine load, the variation of gas residence time within the wESP from approximately 0.1 to approximately 0.4 s led to a substantial increase in the collection efficiency from 67% to 96%. In addition, collection efficiency was found to be directly related to the applied voltage, with increasing collection efficiency measured for increases in applied voltage. The collection efficiency based on particle size had a minimum for sizes between 20 and 50 nm, but at optimal wESP operating conditions it was possible to remove over 90% of all particle sizes. A comparison of measured and calculated collection efficiencies reveals that the measured values are significantly higher than the predicted values based on the well-known Deutsch equation.

Characterization of Major Chemical Components of Fine Particulate Matter in North Carolina

This paper presents measurements of daily sampling of fine particulate matter (PM2.5) and its major chemical components at three urban and one rural locations in North Carolina during 2002. At both urban and rural sites, the major insoluble component of PM2.5 is organic matter, and the major soluble components are sulfate (SO4 2−), ammonium (NH4 +), and nitrate (NO3 −). NH4 + is neutralized mainly by SO4 2− rather than by NO3 −, except in winter when SO4 2− concentration is relatively low, whereas NO3 − concentration is high. The equivalent ratio of NH4 + to the sum of SO4 2− and NO3 − is <1, suggesting that SO4 2−and NO3 −are not completely neutralized by NH4 +. At both rural and urban sites, SO4 2−concentration displays a maximum in summer and a minimum in winter, whereas NO3 −displays an opposite seasonal trend. Mass ratio of NO3 − to SO4 2−is consistently <1 at all sites, suggesting that stationary source emissions may play an important role in PM2.5 formation in those areas. Organic carbon and elemental carbon are well correlated at three urban sites although they are poorly correlated at the agriculture site. Other than the daily samples, hourly samples were measured at one urban site. PM2.5 mass concen trations display a peak in early morning, and a second peak in late afternoon. Back trajectory analysis shows that air masses with lower PM2.5 mass content mainly originate from the marine environment or from a continental environment but with a strong subsidence from the upper troposphere. Air masses with high PM2.5 mass concentrations are largely from continental sources. Our study of fine particulate matter and its chemical composition in North Carolina provides crucial information that may be used to determine the efficacy of the new National Ambient Air Quality Standard (NAAQS) for PM fine. Moreover, the gas-to-particle conversion processes provide improved prediction of long-range transport of pollutants and air quality.

Feynman-alpha experiment with stationary multiple emission sources

In order to verify the Feynman-alpha formula with stationary multiple emission sources [Pázsit, I., Yamane, Y., 1998. Nuclear Instruments and Methods A403, 431–441], a series of experiments were performed by using three different neutron sources, i.e., an Am–Be, a 252Cf, and a randomly triggered D–T pulsed neutron generator. As a result, it was found that the prompt neutron decay constant evaluated from the measured Y-function was hardly affected by the difference of neutron sources that have respective source multiplicities. On the other hand, it was demonstrated that the amplitude of Y-function, i.e., the correlation amplitude, depended on both the subcriticality and the neutron source multiplicity. These experimental facts agreed with the theoretical prospects that were deduced from the Feynman-alpha formula with multiple emission sources. Therefore, it was concluded that the validity of this formula was experimentally shown.

Emissions of Polychlorinated Dibenzo-p-Dioxins and Dibenzofurans from Various Stationary Sources

This work investigated the characteristics of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) in stack-flue gases from six stationary emission sources in five types of incinerators: industrial waste incinerator (IWI), small-scale municipal solid waste incinerator (MSWI), medical waste incinerator (MWI), cement kilns (CK), and crematories (CR). These characteristics were further investigated using factor analysis and cluster analysis. Experimental results reveal that PCDDs dominate MSWI and CR, and PCDFs dominate IWIa, IWIb, CK and MWIs. The factor analysis results showed that CR and MSWI have similar fingerprints, as do IWIb and MWI3. The cluster analysis showed that if a vertical line is cut at a rescaled distance of four, then the PCDD/F congener profiles fall into four groups. The indicators of PCDD/Fs are OCDD, 1,2,3,4,6,7,8-HpCDF, 2,3,4,7,8-PeCDF, and 1,2,3,4,6,7,8-HpCDD. The emission factors of PCDD/Fs herein were from 0.0433 (CK) to 18.7 (MSWI) μg I-TEQ/ton-feedstock.

대구지역 대기 중 VOCs 농도 및 발생원 특성

In recent days, photochemical smog due to the rapid industry development and vehicle increasement has become a critical pollutant in the metropolitan area and the number of ozone alarm signal has increased every year. This research was performed to evaluate VOCs emission source characteristics and concentration of VOCs in Daegu. The site average concentration was observed in the following order: industrial area > commercial area > residential area. Most of the VOCs species except toluene showed variations with higher concentration during nighttime, and lower concentration during the daytime. The major VOCs of stationary emission source were BTEX(benzene, toluene, ethylbenzene. xylene) and methylene chloride, trichloroethene and styrene. Also, those of automobile exhaust were toluene and benzene. Also, the major VOCs concentration emited by the vehicle fuel was observed in the following order: gasoline > light oil > liquefied petroleum gas (L.P.G). Correlation coefficients values were estimated between major VOCs such as toluene, ethylbenzene, m,p-xylene, o-xylene. Results showed that correlation coefficient values were significant magnitude above 0.76. Also, there showed highly significant correlations among ethyl benzene, m,p-xylene, and o-xylene concentration(Pearson correlation coefficients, r=0.868-0.982). Calculated correlation coefficients among commercial area,industrial area and residential area were 0.934-0.981, they showed high correlation. There showed highly correlation between stationary emission source and industrial area, compared with commercial area and residential area. Also, calculated correlation coefficients among commercial area, industrial area, residential area and automobile exhaust were 0.732, 0.725, 0.777, respectively.

Major chemical components of PM2.5 in Milan (Italy)

PM2.5 speciation for the major chemical components has been performed on 109 daily samples collected by a high-volume gravimetric automatic sequential sampler. The 24-h sampling campaigns have been performed at an urban background (UB) site and at a tunnel site in the city of Milan. PM2.5-loaded filters are analysed for the main ionic components (chloride, nitrate, sulphate, ammonium) and the carbon species, elemental carbon (EC) and organic carbon (OC). The species analysed identify on average about 90% of the total mass sampled in the UB site and about 80% of the total mass sampled in the tunnel site. For the latter site a more complete characterisation, accounting for elemental composition, is performed: mass closure that also includes crustal fraction and metal oxides results in a slight overestimation (5%) of the total PM2.5 mass. Based on elemental composition data, the role of the potential sources of crustal and anthropogenic components is identified by the enrichment factor technique. The values obtained for the speciation are typical of urban areas and point out a strong contribution of the secondary source and a small contribution from the emissions of stationary sources in winter. A 0.9 value for the ratio between organic compounds and elemental carbon in PM2.5 samples collected at the tunnel site is observed. Applying the OC/EC ratio approach, this value, representative of the real traffic emissions for the circulating vehicle fleet in Milan, is used for the determination of primary organic aerosols due to traffic in ambient PM2.5. The primary contribution of the traffic source, in terms of carbonaceous matter (EC and primary organic aerosols), is estimated in 6% and 11% of the total PM2.5 mass, respectively, in the cold and warm season. The same OC/EC ratio approach also allows for the evaluation of secondary organic aerosols (SOA) presence in warm season PM2.5 samples: SOA is about 85% of total particulate organic matter and 30% of the total PM2.5 mass. Results obtained for the primary contribution of traffic and for SOA contribution to PM2.5 concentration levels confirm that traffic restriction interventions are not effective to provide relevant short-term air quality improvement. The need to control the emission of the precursors of PM2.5 secondary components is pointed out.