Fine Particle Mass Research Articles

Impact of a new condensed toluene mechanism on air quality model predictions in the US

Abstract. A new condensed toluene mechanism is incorporated into the Community Multiscale Air Quality Modeling system. Model simulations are performed using the CB05 chemical mechanism containing the existing (base) and the new toluene mechanism for the western and eastern US for a summer month. With current estimates of tropospheric emission burden, the new toluene mechanism increases monthly mean daily maximum 8-h ozone by 1.0–3.0 ppbv in Los Angeles, Portland, Seattle, Chicago, Cleveland, northeastern US, and Detroit compared to that with the base toluene chemistry. It reduces model mean bias for ozone at elevated observed ozone concentrations. While the new mechanism increases predicted ozone, it does not enhance ozone production efficiency. A sensitivity study suggests that it can further enhance ozone if elevated toluene emissions are present. While it increases in-cloud secondary organic aerosol substantially, its impact on total fine particle mass concentration is small.

Hydrogen peroxide generation from α- and β-pinene and toluene secondary organic aerosols

Abstract In-particle reactions and reactivity may play a role in aerosol aging as well as health effects associated with airborne particles. One of the main hypotheses for the species causing the observed health effects are reactive oxygen species including hydrogen peroxide (H2O2). Secondary organic aerosol (SOA), the focus of this study, comprises a major fraction of ambient fine mode particle mass. SOA were generated via dark ozonolysis of α-pinene and β-pinene, as well as photochemical oxidation of α-pinene, β-pinene, and toluene. SOA particles generate a considerable amount of H2O2 in the aqueous phase. For the same particle mass, α-pinene and β-pinene SOA have higher H2O2 generation ability than toluene SOA. H2O2 levels were sensitive to the pH of the particle extraction solutions, decreasing as the pH was increased. SOA samples aged for 20 h in room air lost a significant fraction of the H2O2 compared to fresh samples. The H2O2 is likely from decomposition or hydrolysis of hydroxyhydroperoxides, peroxic acids and related species for α- and β-pinene SOA, and from redox cycling of quinoid compounds for toluene SOA. This study provides the first quantitative measurement of H2O2 for a range of SOA particle types.

Source identification of ambient PM2.5 for inhalation exposure studies in Steubenville, Ohio using highly time-resolved measurements

Abstract Recent epidemiological and toxicological studies have suggested that short-term elevations of ambient fine particle mass concentrations (aerodynamic diameter The average ambient PM2.5 filter-based mass concentration during the 8-hour summer exposure study period was 26 ± 11 μg m−3. Results from PMF indicated that six major factors contributed to the ambient PM2.5 mass during this time: coal combustion/secondary (39 ± 46%), mobile sources (12 ± 14%), metal coating/processing (10 ± 11%), iron and steel manufacturing (5 ± 5%), Pb factor (5 ± 8%), and incineration/smelting (1 ± 3%). The objectives of this paper are (1) to present chemical composition of ambient PM2.5 and its potential emission sources in Steubenville; and (2) to evaluate the PMF modeling results using observed meteorological data. These semi-continuous sampling approaches to determine potential emission sources have significant advantages over similar analyses using samples averaged over 8–24 h, and are being utilized by our group to determine associations of PM with acute CV responses from animal inhalation toxicology field studies.

Spatiotemporal Patterns of Ultrafine Particle Counts and Fine Particle Mass in Neighborhoods Surrounding an Airport

PP-30-019 Background/Aims: Previous studies have demonstrated significant contributions from aircraft to ultrafine particle counts near airports, but studies to date have not characterized spatial patterns in residential settings near airports and have not formally isolated the contribution of aircraft from other local sources. In this study, our objective was to determine the contribution of landing and takeoff (LTO) activity to concentrations of ultrafine particles as well as fine particulate matter (PM2.5) near TF Green Airport in Warwick, RI. Methods: A mobile monitoring protocol was implemented in 2 one-week campaigns in the spring and summer of 2008. Field teams were outfitted with backpacks containing water-based condensation particle counters to measure ultrafine particle levels, continuous monitors for PM2.5, and a GPS. Mobile sampling routes captured neighborhoods in all compass directions and were implemented to ensure sufficient spatiotemporal coverage. Regression models included as predictors of concentrations meteorological characteristics, source terms, and distance variables. To better pinpoint the timing in the LTO cycle most contributing to elevated concentrations, and to capture variability across aircraft and the spatiotemporal complexity of our data, we used distributed lag models for flight activity and incorporated emissions proxies for all individual aircraft. Results: Results suggest significant positive associations between ultrafine particle concentrations and both departures and arrivals, with departures having larger effects and the distributed lag modeling indicating the strongest association with predeparture taxing and the take-off process. Causal linkages with the LTO cycle were further enhanced by generalized additive models for wind speed and direction, which demonstrate an enhanced signal from LTO activities at higher wind speeds with a greater indication of local traffic contributions at low wind speeds. Conclusion: Our analysis allows for quantification of the marginal contribution of airport sources and characterization of spatiotemporal concentration patterns, providing insight for urban communities regarding the impact of airport activities on local air quality.

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

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.

Characterization of aerosol black carbon over a tropical semi-arid region of Anantapur, India

Black carbon (BC) aerosol mass concentrations measured using an aethalometer at Anantapur, a semi-arid tropical station in the southern part of peninsular India, from August 2006 to July 2007 are analyzed. Seasonal and diurnal variations of BC in relation to changes in the regional meteorological conditions have been studied along with the mass fraction of BC to the total aerosol mass concentration (Mt) and fine particle mass (FPM) concentration in different months. The data collected during the study period shows that the annual average BC mass concentration at Anantapur is 1.97±0.12μgm−3. Seasonal variations of BC aerosol mass concentration showed high during the dry (winter and summer) seasons and low during the post-monsoon followed by the monsoon seasons. Diurnal variations of BC aerosols attain a gradual build up in BC concentration from morning and a sharp peak occurs between 07:00 and 09:00h almost an hour after local sunrise and a broad nocturnal peak from 19:00 to 21:00h with a minimum in noon hours. The ratio of BC to the fine particle mass concentration was high during the dry season and low during the monsoon season. The regression analysis between BC mass concentration and wind speed indicates that, with increase in wind speeds the BC mass concentrations would decrease and vice-versa. Aerosol BC mass concentration shows a significant positive correlation with total mass concentration (Mt) and aerosol optical depth (AOD, τp) at 500nm.

NMOC, ozone, and organic aerosol in the southeastern United States, 1999–2007: 3. Origins of organic aerosol in Atlanta, Georgia, and surrounding areas

Abstract Carbonaceous compounds constitute a major fraction of the fine particle mass at locations throughout North America; much of the condensed-phase organic carbon (OC) is produced in the atmosphere from NMOC reactions as “secondary” OC (SOC). Ten years of particulate carbon and speciated non-methane organic compound (NMOC) data combined with other measurements from Southeastern Aerosol Research and Characterization (SEARCH) and other sites provide insight into the association between elemental carbon (EC), OC and NMOCs. Data are analyzed to characterize the OC and SOC contrasts between urban Atlanta, Georgia, and nearby non-urban conditions in the Southeast. Analysis of the monitoring record indicates that the mean Atlanta urban excess of total carbon (TC) is 2.1–2.8 μg m −3 . The OC/EC ratio of the Atlanta urban excess is in the range 1.3 to 1.8, consistent with OC/EC ratios observed in motor vehicle emissions and a fossil carbon source of urban excess TC. Carbon isotope analysis of a subset of particle samples demonstrates that the urban excess is mainly fossil in origin, even though the majority of the TC is modern at both urban and non-urban sites. Temperature-dependent partitioning of OC between gas and condensed phases cannot explain the observed diurnal and seasonal variations of OC/CO, EC/CO, and OC/EC ratios. Alternatively, a hypothesis involving vertical mixing of OC-enriched air from aloft is supported by the seasonal and diurnal OC, isopentane, aromatic and isoprene observations at the ground. A statistical model is applied to indicate the relative significance of aerometric factors affecting OC and EC concentrations, including meteorological and pollutant associations. The model results demonstrate strong linkages between fine particle carbon and pollutant indicators of source emissions compared with meteorological factors; the model results show weaker dependence of OC on meteorological factors than is the case for ozone (O 3 ) concentrations.

Multi-criteria ranking and receptor modelling of airborne fine particles at three sites in the Pearl River Delta region of China

The multi-criteria decision making methods, Preference Ranking Organization METHods for Enrichment Evaluation (PROMETHEE) and Graphical Analysis for Interactive Assistance (GAIA), and the two-way Positive Matrix Factorization (PMF) receptor model were applied to airborne fine particle compositional data collected at three sites in Hong Kong during two monitoring campaigns held from November 2000 to October 2001 and November 2004 to October 2005. PROMETHEE/GAIA indicated that the three sites were worse during the later monitoring campaign, and that the order of the air quality at the sites during each campaign was: rural site > urban site > roadside site. The PMF analysis on the other hand, identified 6 common sources at all of the sites (diesel vehicle, fresh sea salt, secondary sulphate, soil, aged sea salt and oil combustion) which accounted for approximately 68.8 ± 8.7% of the fine particle mass at the sites. In addition, road dust, gasoline vehicle, biomass burning, secondary nitrate, and metal processing were identified at some of the sites. Secondary sulphate was found to be the highest contributor to the fine particle mass at the rural and urban sites with vehicle emission as a high contributor to the roadside site. The PMF results are broadly similar to those obtained in a previous analysis by PCA/APCS. However, the PMF analysis resolved more factors at each site than the PCA/APCS. In addition, the study demonstrated that combined results from multi-criteria decision making analysis and receptor modelling can provide more detailed information that can be used to formulate the scientific basis for mitigating air pollution in the region.

Canadian National Air Pollution Surveillance (NAPS) PM2.5 speciation program: Methodology and PM2.5 chemical composition for the years 2003–2008

Abstract The Canadian National Air Pollution Surveillance (NAPS) network, monitoring criteria gases (CO, O 3 , NO x , and SO 2 ), PM 2.5 , PM 10 , volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs) and particle chemical mass and composition, has been in operation for over 40 years. Since 1984 both fine ( 2.5 ) and coarse (2.5–10 μm – PM 10–2.5 ) particle mass measurements have been made at NAPS network sites using dichotomous samplers. In January 2003, the NAPS PM 2.5 speciation program was initiated with the purpose of measuring all major components of PM 2.5 , including ammonium nitrate, ammonium sulphate, metals, and organic and elemental carbon. The present paper describes the improved sampling (e.g. Teflon/Nylon filter packs for nitrate loss, and an active blank for each and every sample in the determination of positive organic carbon artifacts), and analytical methods used in the Canadian NAPS PM 2.5 speciation program. A detailed dataset was then analyzed for seasonal and geographical variations in the major components of 24-h time integrated PM 2.5 samples collected at eight urban and three rural measurement sites across Canada (2003–2008). Chemical mass reconstruction was used for assessment of the adequacy of selected sampling and chemical parameters as well as for the determination of the relative contributions of different compound classes to PM 2.5 mass. The highest frequency of PM 2.5 episodes exceeding 30 μg m −3 were observed in Ontario and southern Quebec. In general, the most important contributions to PM 2.5 mass were secondary aerosol sulphate and nitrate (38–63% for western sites and 3–44% for eastern sites), depending on the season. Organic matter (OM) was found to be the second most important component (21–45%), while particle-bound water (PBW) accounted for 6–12% of the PM 2.5 mass. Golden B.C. was an exception, exhibiting high levels of OM (60–70%) and low levels of PBW (∼3%).

Fabrication of Cu-Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; Composites by Simplified Internal Oxidation Process

Cu-Al2O3 composites were prepared by a new simplified internal oxidation process integrating with powder metallurgical process, and then the hot extrusion and the cold rolling processes were carried out. The microstructure, electrical conductivity, hardness, tensile strength and thermal stability of the composites were investigated. The results show that Cu-Al2O3 composites were fabricated successfully by the simplified process in which internal oxidation completed during the sintering. There are a mass of fine Al2O3 particles in size varying from 5 nm to 20nm dispersed in copper matrix after sintering 950 for 4h. After sintered at 950 for 4h and extruded at 950 followed with the cold deforming of 80%, the electrical conductivity, hardness, tensile strength and softening temperature of composite reach 81％IACS, 137HV, 561MPa and 850 respectively. It is considered that the dispersion strengthening and strain hardening have greatly contribution to the Cu-Al2O3 composites fabricated with the simplified process.

Updating the Conceptual Model for Fine Particle Mass Emissions from Combustion Systems Allen L. Robinson

Atmospheric transformations determine the contribution of emissions from combustion systems to fine particulate matter (PM) mass. For example, combustion systems emit vapors that condense onto existing particles or form new particles as the emissions are cooled and diluted. Upon entering the atmosphere, emissions are exposed to atmospheric oxidants and sunlight, which causes them to evolve chemically and physically, generating secondary PM. This review discusses these transformations, focusing on organic PM. Organic PM emissions are semi -volatile at atmospheric conditions and thus their partitioning varies continuously with changing temperature and concentration. Because organics contribute a large portion of the PM mass emitted by most combustion sources, these emissions cannot be represented using a traditional, static emission factor. Instead, knowledge of the volatility distribution of emissions is required to explicitly account for changes in gas-particle partitioning. This requires updating how PM emissions from combustion systems are measured and simulated from combustion systems. Secondary PM production often greatly exceeds the direct or primary PM emissions; therefore, secondary PM must be included in any assessment of the contribution of combustion systems to ambient PM concentrations. Low-volatility organic vapors emitted by combustion systems appear to be very important secondary PM precursors that are poorly accounted for in inventories and models. The review concludes by discussing the implications that the dynamic nature of these PM emissions have on source testing for emission inventory development and regulatory purposes. This discussion highlights important linkages between primary and secondary PM, which could lead to simplified certification test procedures while capturing the emission components that contribute most to atmospheric PM mass.

Effects of Aerosol Hygroscopicity on Fine Particle Mass Concentration and Light Extinction Coefficient at Seoul and Gosan in Korea

The sensitivity of aerosol light extinction coefficient to the aerosol chemical composition change is estimated by (1) calculating the aerosol water content and chemical concentrations by a gas/particle equilibrium model and (2) calculating the aerosol light extinction coefficient by a Mie theory based optical model. The major chemical species are total (gas and particle phase) sulfuric acid, total nitric acid, and total ammonia which are based on the measurement data at Seoul and Gosan. At Seoul, since there were enough ammonia to neutralize both total sulfuric acid and total nitric acid, the dry ionic concentration is most sensitive to the variation of the total nitric acid level, while the total mass concentration (ionic concentration plus water content) and thus, the aerosol light extinction coefficient are primarily determined by the total sulfuric acid. At Gosan, since the concentration of ambient sulfuric acid was the highest among the inorganic species, sulfate salts determined aerosol hygroscopicity. Thus, both ionic and total mass concentration, and resultant aerosol light extinction coefficient are primarily determined by the sulfuric acid level.

Health impacts of particulate matter in five major Estonian towns: main sources of exposure and local differences

Particulate matter (PM) is the major air pollution problem with health impacts in Estonia. The prevailing sources of particles are traffic and local heating. In this study, we quantified the health effects of PM in neighbourhoods of five main cities with a health impact assessment (HIA) approach that uses information on exposure, baseline mortality/morbidity and exposure–response relationships from previous epidemiological studies. The exposure was defined as modelled PM2.5 annual levels and daily averages of PM10 (monitoring data in Tallinn and Kohtla-Jarve and modelled levels in Tartu, Narva and Parnu). The modelled results were validated with data from monitoring stations and additional measuring programmes. The annual average concentration of PM2.5 in the neighbourhoods studied varied from 7.6 to 23.6 μg m−3. The analysis indicated that the exposure above natural background corresponds to 462 [95% confidence interval (CI) 120–815] premature deaths, resulting in 6,034 (95% CI 1,583–10,309) years of life lost per year. The average decrease in life-expectancy at birth per resident of Tallinn was estimated to be 0.63 (95% CI 0.16–1.08) years. In the polluted city centres, this average decrease may reach >1 year and in Parnu, it may reach 0.95 year. However, in the least polluted neighbourhood, the decrease of life expectancy was only 0.17 years. In addition, 231 (95% CI 145–306) respiratory and 338 (95% CI 205–454) cardiovascular hospitalisations per year could be expected. The majority of the external costs are related to the long-term effects on mortality and amount to €270 (95% CI 190–350) million annually. In comparison, the costs of hospitalisations contribute just €1.1 (95% CI 0.6–1.6) million. The main differences in health impacts were mostly driven by differences in the pollution sources, the magnitude of such sources and distribution patterns in the atmosphere. The smallest health effects, with the exception of the green residential areas, were observed in the industrial cities Kohtla-Jarve and Narva (due to the small share contributed by local residential heating and relatively little car traffic). However, it is questionable whether the mass of fine particles is the best indicator of air pollution risk in such areas.

Effects of Aerosol Hygroscopicity on Fine Particle Mass Concentration and Light Extinction Coefficient at Seoul and Gosan in Korea

Effects of Aerosol Hygroscopicity on Fine Particle Mass Concentration and Light Extinction Coefficient at Seoul and Gosan in Korea

Experimental investigation of engine emissions with marine gas oil-oxygenate blends

This paper investigates the diesel engine performance and exhaust emissions with marine gas oil-alternative fuel additive. Marine gas oil (MGO) was selected as base fuel for the engine experiments. An oxygenate, diethylene glycol dimethyl ether (DGM), and a biodiesel (BD) jatropha oil methyl ester (JOME) with a volume of 10% were blended with the MGO fuel. JOME was derived from inedible jatropha oil. Lower emissions with diesel-BD blends (soybean methyl ester, rapeseed methyl ester etc.) have been established so far, but the effect of MGO-BD (JOME) blends on engine performance and emissions has been a growing interest as JOME (BD) is derived from inedible oil and MGO is frequently used in maritime transports. No phase separation between MGO–DGM and MGO–JOME blends was found. The neat MGO, MGO–DGM and MGO–JOME blends are termed as MGO, Ox10 and B10 respectively. The experiments were conducted with a six-cylinder, four-stroke, turbocharged, direct-injection Scania DC 1102 (DI) diesel engine. The experimental results showed significant reductions in fine particle number and mass emissions, PM and smoke emissions with Ox10 and B10 fuels compared to the MGO fuel. Other emissions including total unburned hydrocarbon (THC), carbon monoxide (CO) and engine noise were also reduced with the Ox10 and B10 fuels, while maintaining similar brake specific fuel consumption (BSFC) and thermal efficiency with MGO fuel. Oxides of nitrogen (NOx) emissions, on the other hand, were slightly higher with the Ox10 and B10 fuels at high engine load conditions.

Sensitivity of the Community Multiscale Air Quality (CMAQ) model v4.7 results for the eastern United States to MM5 and WRF meteorological drivers

Abstract. This paper presents a comparison of the operational performances of two Community Multiscale Air Quality (CMAQ) model v4.7 simulations that utilize input data from the 5th-generation Mesoscale Model (MM5) and the Weather Research and Forecasting (WRF) meteorological models. Two sets of CMAQ model simulations were performed for January and August 2006. One set utilized MM5 meteorology (MM5-CMAQ) and the other utilized WRF meteorology (WRF-CMAQ), while all other model inputs and options were kept the same. For January, predicted ozone (O3) mixing ratios were higher in the Southeast and lower Mid-west regions in the WRF-CMAQ simulation, resulting in slightly higher bias and error as compared to the MM5-CMAQ simulations. The higher predicted O3 mixing ratios are attributed to less dry deposition of O3 in the WRF-CMAQ simulation due to differences in the calculation of the vegetation fraction between the MM5 and WRF models. The WRF-CMAQ results showed better performance for particulate sulfate (SO42−), similar performance for nitrate (NO3−), and slightly worse performance for nitric acid (HNO3), total carbon (TC) and total fine particulate (PM2.5) mass than the corresponding MM5-CMAQ results. For August, predictions of O3 were notably higher in the WRF-CMAQ simulation, particularly in the southern United States, resulting in increased model bias. Concentrations of predicted particulate SO42− were lower in the region surrounding the Ohio Valley and higher along the Gulf of Mexico in the WRF-CMAQ simulation, contributing to poorer model performance. The primary causes of the differences in the MM5-CMAQ and WRF-CMAQ simulations appear to be due to differences in the calculation of wind speed, planetary boundary layer height, cloud cover and the friction velocity (u∗) in the MM5 and WRF model simulations, while differences in the calculation of vegetation fraction and several other parameters result in smaller differences in the predicted CMAQ model concentrations. The performance for SO42−, NO3− and NH4+ wet deposition was similar for both simulations for January and August.

Biomass burning aerosol emissions from vegetation fires: particle number and mass emission factors and size distributions

Abstract. Aerosol emissions from vegetation fires have a large impact on air quality and climate. In this study, we use published experimental data and different fitting procedures to derive dynamic particle number and mass emission factors (EFPN, EFPM) related to the fuel type, burning conditions and the mass of dry fuel burned, as well as characteristic CO-referenced emission ratios (PN/CO, PM/CO). Moreover, we explore and characterize the variability of the particle size distribution of fresh smoke, which is typically dominated by a lognormal accumulation mode with count median diameter around 120 nm (depending on age, fuel and combustion efficiency), and its effect on the relationship between particle number and mass emission factors. For the particle number emission factor of vegetation fires, we found no dependence on fuel type and obtained the following parameterization as a function of modified combustion efficiency (MCE): EFPN=34×1015×(1−MCE) kg−1±1015 kg−1 with regard to dry fuel mass (d.m.). For the fine particle mass emission factors (EFPM) we obtained (86–85×MCE) g kg−1±3 g kg−1 as an average for all investigated fires; (93–90×MCE) g kg−1±4 g kg−1 for forest; (67–65×MCE) g kg−1±2 g kg−1 for savanna; (63–62×MCE) g kg−1±1 g kg−1 for grass. For the PN/CO emission ratio we obtained an average of (34±16) cm−3 ppb−1 exhibiting no systematic dependence on fuel type or combustion efficiency. The average PM/CO emission ratios were (0.09±0.04) g g−1 for all investigated fires; (0.13±0.05) g g−1 for forest; (0.08±0.03) g g−1 for savanna; and (0.07±0.03) g g−1 for grass. The results are consistent with each other, given that particles from forest fires are on average larger than those from savanna and grass fires. This assumption and the above parameterizations represent the current state of knowledge, but they are based on a rather limited amount of experimental data which should be complemented by further measurements. Nevertheless, the presented parameterizations appear sufficiently robust for exploring the influence of vegetation fires on aerosol particle number and mass concentrations in regional and global model studies.

Contributions from DMS and ship emissions to CCN observed over the summertime North Pacific

Abstract. Measurements of cloud condensation nuclei (CCN) made over the North Pacific Ocean in July 2002 are analysed with concurrent measurements of aerosol number, mass and composition. Overall the CCN are controlled by the sulphate, including one case that suggests particle nucleation and growth resulting from dimethyl sulphide oxidation that enhanced CCN concentrations. Hourly CCN concentrations are correlated with concentrations of sulphate plus methanesulphonic acid (MSA) over the entire study period (r2=0.43 and 0.52 for supersaturations of 0.34% and 0.19%, respectively), and are not well correlated with other organics (r2&lt;0.2). One case study reveals elevated mass and number concentrations of ultrafine and fine organic particles due to regional ship emissions, identified through quadrupole aerosol mass spectrometer (Q-AMS) measurements, during which organic mass concentrations are correlated with CCN values (r2=0.39 and 0.46 for supersaturations of 0.19% and 0.34%, respectively). The evolution of the time series and mass distributions of organics, sulphate and MSA over this timeframe indicate that the regional distribution of small, diffuse ship-sourced organic particles act as condensation sites for sulphur species, resulting in a subsequent increase in number concentrations of CCN. We conclude that, where present, direct emissions of anthropogenic organic particles may exert a strong control on marine CCN concentrations once diffused into the marine atmosphere, by acting as condensation sites for biogenic and anthropogenic sulphur species.

Сравнительная оценка экологичности барабанных и дисковых колесных тормозных механизмов автотранс портных средств

It is well-known that automobile transport as well as industry are the main sources of air pollution. In addition to exhaust gases, the flow of traffic releases a cloud of dust, consisting of over 60% of micro- and ultramicroscopic particles with radius of 10.0–0.25 µm, which are formed due to wheel abrasion (caused by the road grip of a tyre) and the use of the brake blocks (in braking).&nbsp;The products formed in the process of wearing of the wheel brake pads are also the sources of the mass of fine dispersed particles over an urban highway.&nbsp;The authors analyse and evaluate ecological characteristics of drum and disk wheel brakes of vehicles. Article in Russian. Ratinių transporto priemonių būgninių&nbsp; ir diskinių stabdžių mechanizmų ekologiškumo lyginamoji analizė Santrauka. Kaip žinoma, automobilių transportas, kaip ir pramonė, yra pagrindiniai aplinkos taršos šaltiniai. Transporto priemonių srautas į aplinką išmeta ne tik didelį kenksmingų deginių kiekį, bet ir daugybę kitų dulkių. Tyrimais nustatyta, kad apie 60 % šių dulkių kiekio sudaro mikroskopinės ir ultramikroskopinės dalelės (jų skersmuo – 10,0–0,25 µm). Šios dalelės susidaro transporto priemonių ratams sąveikaujant su kelio dangos paviršiumi (pavyzdžiui, intensyviai stabdant) ir tarpusavyje sąveikaujant transporto priemonės stabdžių elementams (pavyzdžiui, stabdžių trinkelių antdėklams sąveikaujant su diskais). Dalelių susidarymo intensyvumui įtakos turi stabdžių mechanizmo sandara, antdėklų frikcinė medžiaga, judėjimo režimas ir pan. Straipsnyje autoriai atlieka įvairių ratinių transporto priemonių būgninių ir diskinių stabdžių mechanizmų ekologiškumo lyginamąją analizę. Reikšminiai žodžiai: transporto priemonė, stabdžių mechanizmas, ekologiškumas, tyrimas. Сравнительная оценка экологичности барабанных и дисковых колесных тормозных механизмов автотранспортных средств Аннотация. Известно, что автомобильный транспорт наряду с промышленностью является одним из основных источников загрязнения атмосферного воздуха. Кроме выбросов отработавших газов, транспортный поток создает облако пыли, состоящее более чем на 60% из микроскопических и ультрамикроскопических частиц радиусом 10,0– 0,25 мкм, которые образуются вследствие истирания колес (при сцеплении с дорогой) и накладок тормозных колодок (при торможении). Источниками массы мелкодисперсных частиц в воздухе городской магистрали, кроме шинной пыли, являются продукты износа тормозных накладок колесных тормозных механизмов. Авторы исследуют и оценивают экологичность барабанных и дисковых колесных тормозных механизмов автотранспортных средств. Ключевые слова: транспорт, автомобиль, тормозной механизм, продукты износа, экологичность.

2006 ~ 2008년 황사기간 중 천안시 대기 입자의 특성 변화

황사기간 중 천안시 대기 입자의 특성 변화를 파악하기 위해, Cascade Impactor를 장착한 High Volume Air Sampler를 이용하여 대기 시료를 채취하여, 대기 입자의 입경별 질량농도 및 이온, 금속 성분의 농도를 황사기간과 비황사기간에 비교 측정하였다. 황사기간 중 일평균 TSP, PM10, PM2.5 평균 농도가 각각 214.9, 160.3, 95.9<TEX>${\mu}\;g/m^3$</TEX>으로, 비황사기간에 비해 각각 평균 3.08, 2.58, 1.95배 증가하였으며, 최대 농도는 TSP, PM10, PM2.5가 각각 850.1, 534.4, 233.3<TEX>${\mu}\;g/m^3$</TEX>으로, 비황사기간에 비해 각각 12.19, 8.60, 4.76배까지 증가하였다. 황사기간 중 농도의 증가는 미세입자보다는 조대입자에서 현저하였으며, 미세입자와 조대입자 모두 수용성 이온성분의 증가는 미미한 반면, 토양의 주요 구성 성분인 Fe, Al, Ti의 증가가 뚜렷이 관측되어, 토양구성 금속성분이 황사기간 중 입자 농도 증가의 주요원인 물질임을 확인할 수 있었다. Changes in aerosol characteristics during 2006 <TEX>${\sim}$</TEX>2008 Asian dust events in Cheoan were investigated by measuring mass, ion and elemental concentrations of fine and coarse particles. The average mass concentrations of daily TSP, PM10, PM2.5 were 214.9, 160.3, and 95.9<TEX>${\mu}\;g/m^3$</TEX>during Asian dust events, which were 3.08, 2.58, and 1.95 times higher than Non-asian dust events. The maximum concentrations of TSP, PM10, and PM2.5 were 850.1, 534.4, and 233.3<TEX>${\mu}\;g/m^3$</TEX>, which were 12.19, 8.60, and 4.76 times higher, respectively. Increases in ion concentrations were not significant during Asian dust events, but elemental concentrations including soil components such as Fe, Al, Ti increased by 17.1 and 43.4 times for fine and coarse particles, respectively. The results clearly indicate that metallic components from soil constituents were the major components in Asian dusts sampled at Cheonan.