WorldWideScience

Sample records for atmospheric ultrafine particles

  1. Ultrafine particles in the atmosphere

    CERN Document Server

    Brown, L M; Harrison, R M; Maynard, A D; Maynard, R L

    2003-01-01

    Following the recognition that airborne particulate matter, even at quite modest concentrations, has an adverse effect on human health, there has been an intense research effort to understand the mechanisms and quantify the effects. One feature that has shone through is the important role of ultrafine particles as a contributor to the adverse effects of airborne particles. In this volume, many of the most distinguished researchers in the field provide a state-of-the-art overview of the scientific and medical research on ultrafine particles. Contents: Measurements of Number, Mass and Size Distr

  2. [Distribution of atmospheric ultrafine particles during haze weather in Hangzhou].

    Science.gov (United States)

    Chen, Qiu-Fang; Sun, Zai; Xie, Xiao-Fang

    2014-08-01

    Atmospheric ultrafine particles (UFPs) were monitored with fast mobility particle sizer (FMPS) in continuous haze weather and the haze fading process during December 6 to 11, 2013 in Hangzhou. Particle concentration and size distribution were studied associated with meteorological factors. The results showed that number concentrations were the highest at night and began to reduce in the morning. There was a small peak at 8 o'clock in the morning and 18 o'clock in the afternoon. It showed an obvious peak traffic source, which indicated that traffic emissions played a great role in the atmospheric pollution. During haze weather, the highest number concentration of UFPs reached 8 x 10(4) cm(-3). Particle size spectrum distribution was bimodal, the peak particle sizes were 15 nm and 100 nm respectively. Majority of UFPs were Aitken mode and Accumulation mode and the size of most particles concentrated near 100 nm. Average CMD(count medium diameter) was 85.89 nm. During haze fading process, number concentration and particles with size around 100 nm began to reduce and peak size shifted to small size. Nuclear modal particles increased and were more than accumulation mode. Average CMD was 58.64 nm. Meteorological factors such as the visibility and wind were negatively correlated with the particle number concentration. Correlation coefficient R were -0.225 and - 0.229. The humidity was correlated with number concentration. Correlation coefficient R was 0.271. The atmosphere was stable in winter and the level temperature had small correlation with number concentration. Therefore, study on distribution of atmospheric ultrafine particles during haze weather had the significance on the formation mechanism and control of haze weather.

  3. Estimation of the contribution of ultrafine particles to lung deposition of particle-bound mutagens in the atmosphere.

    Science.gov (United States)

    Kawanaka, Youhei; Matsumoto, Emiko; Sakamoto, Kazuhiko; Yun, Sun-Ja

    2011-02-15

    The present study was performed to estimate the contributions of fine and ultrafine particles to the lung deposition of particle-bound mutagens in the atmosphere. This is the first estimation of the respiratory deposition of atmospheric particle-bound mutagens. Direct and S9-mediated mutagenicity of size-fractionated particulate matter (PM) collected at roadside and suburban sites was determined by the Ames test using Salmonella typhimurium strain TA98. Regional deposition efficiencies in the human respiratory tract of direct and S9-mediated mutagens in each size fraction were calculated using the LUDEP computer-based model. The model calculations showed that about 95% of the lung deposition of inhaled mutagens is caused by fine particles for both roadside and suburban atmospheres. Importantly, ultrafine particles were shown to contribute to the deposition of mutagens in the alveolar region of the lung by as much as 29% (+S9) and 26% (-S9) for the roadside atmosphere and 11% (+S9) and 13% (-S9) for the suburban atmosphere, although ultrafine particles contribute very little to the PM mass concentration. These results indicated that ultrafine particles play an important role as carriers of mutagens into the lung.

  4. Ultrafine particles

    DEFF Research Database (Denmark)

    Bekö, Gabriel; Weschler, Charles J.; Wierzbicka, Aneta;

    2013-01-01

    Particle number (PN) concentrations (10-300 nm in size) were continuously measured over a period of ∼45 h in 56 residences of nonsmokers in Copenhagen, Denmark. The highest concentrations were measured when occupants were present and awake (geometric mean, GM: 22.3 × 103 cm-3), the lowest when...... the homes were vacant (GM: 6.1 × 103 cm-3) or the occupants were asleep (GM: 5.1 × 103 cm-3). Diary entries regarding occupancy and particle related activities were used to identify source events and apportion the daily integrated exposure among sources. Source events clearly resulted in increased PN...... concentrations and decreased average particle diameter. For a given event, elevated particle concentrations persisted for several hours after the emission of fresh particles ceased. The residential daily integrated PN exposure in the 56 homes ranged between 37 × 103 and 6.0 × 106 particles per cm3·h/day (GM: 3...

  5. [Study on number concentration distribution of atmospheric ultrafine particles in Hangzhou].

    Science.gov (United States)

    Xie, Xiao-Fang; Sun, Zai; Fu, Zhi-Min; Yang, Wen-Jun; Lin, Jian-Zhong

    2013-02-01

    Atmospheric ultrafine particles (UFPs) were measured with fast mobility particle sizer(FMPS) in Hangzhou, during March 2011 to February 2012. The number concentration and size distribution of UFPs associated with meteorology were studied. The results showed that the number concentration of UFPs was logarithmic bi-modal distribution, and the seasonal levels presented winter > summer > spring> autumn. The highest monthly average concentration was 3.56 x 10(4) cm-3 in December and the lowest was 2.51 x 10(4) cm-3 in October. The seasonal values of count medium diameter(CMD) were spring > winter > autumn > summer. The highest monthly average CMD was 53. 51 nm in April and the lowest was 16.68 nm in June. Meteorological factors had effects on concentration of UFPs.

  6. Size distributions of polycyclic aromatic hydrocarbons in the atmosphere and estimation of the contribution of ultrafine particles to their lung deposition.

    Science.gov (United States)

    Kawanaka, Youhei; Tsuchiya, Yoshiteru; Yun, Sun-Ja; Sakamoto, Kazuhiko

    2009-09-01

    This is the first estimation of the contribution of ultrafine particles to the lung deposition of particle-bound polycyclic aromatic hydrocarbons (PAHs) in the atmosphere. The size distributions of nine PAHs (4-6 rings) were measured at roadside and suburban sites in winter in Japan. Deposition efficiencies and fluxes of PAHs in ultrafine mode (2.1 microm) to the human respiratory tract were calculated using the LUDEP computer-based model. From 10%-15% and 4.2%-6.9% of target PAHs were distributed in the ultrafine mode in the roadside and suburban atmosphere, respectively. The model calculations showed that as much as 18%-19% and 16%-17% of inhaled PAHs are deposited in the alveolar region of the lung for the roadside and suburban atmosphere, respectively. Total deposition fluxes of target PAHs in the alveolar region were about 1.5-fold greater for the roadside atmosphere than for the suburban atmosphere. Importantly, ultrafine particles were shown to contribute as much as 23%-30% and 10%-16% to PAH deposition in the alveolar region for the roadside and suburban atmosphere, respectively, although the contributions of ultrafine particles to the total particulate matter masswere only 2.3% in the roadside atmosphere and 1.3% in the suburban atmosphere. These results indicated that ultrafine particles are significant contributors to the deposition of PAHs into the alveolar region of the lung.

  7. Production, growth and properties of ultrafine atmospheric aerosol particles in an urban environment

    Directory of Open Access Journals (Sweden)

    I. Salma

    2011-02-01

    Full Text Available Number concentrations of atmospheric aerosol particles were measured by a flow-switching type differential mobility particle sizer in an electrical mobility diameter range of 6–1000 nm in 30 channels near central Budapest with a time resolution of 10 min continuously from 3 November 2008 to 2 November 2009. Daily median number concentrations of particles varied from 3.8 × 103 to 29 ×103 cm−3 with a yearly median of 11.8 × 103 cm−3. Contribution of ultrafine particles to the total particle number ranged from 58 to 92% with a mean ratio and standard deviation of (79 ± 6%. Typical diurnal variation of the particle number concentration was related to the major emission patterns in cities, new particle formation, sinks of particles and meteorology. Shapes of the monthly mean number size distributions were similar to each other. Overall mean for the number median mobility diameter of the Aitken and accumulation modes were 26 and 93 nm, respectively, which are substantially smaller than for rural or background environments. The Aitken and accumulation modes contributed similarly to the total particle number concentrations at the actual measurement location. New particle formation and growth unambiguously occurred on 83 days, which represent 27% of all relevant days. Hence, new particle formation and growth are not rare phenomena in Budapest. Their frequency showed an apparent seasonal variation with a minimum of 7.3% in winter and a maximum of 44% in spring. New particle formation events were linked to increased gas-phase H2SO4 concentrations. In the studied area, new particle formation is mainly affected by condensation sink and solar radiation. The formation process seems to be not sensitive to SO2, which was present in a yearly median concentration of 6.7 μg m−3. This suggests that the precursor gas was always available in excess

  8. Ultrafine Condensation Particle Counter Instrument Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Kuang, C. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2016-02-01

    The Model 3776 Ultrafine Condensation Particle Counter (UCPC; pictured in Appendix A) is designed for researchers interested in airborne particles smaller than 20 nm. With sensitivity to particles down to 2.5 nm in diameter, this UCPC is ideally suited for atmospheric and climate research, particle formation and growth studies, combustion and engine exhaust research, and nanotechnology research.

  9. Measurements of hygroscopicity and volatility of atmospheric ultrafine particles in the rural Pearl River Delta area of China

    Science.gov (United States)

    Kim, Jae-Seok; Kim, Young J.; Park, Kihong

    2011-09-01

    A hygroscopicity and volatility tandem differential mobility analyzer (HVTDMA) technique was used to determine the time- and size-resolved properties of ultrafine particles and to infer relative volume fractions of non-volatile and non-hygroscopic (NV_NH), volatile and non-hygroscopic (V_NH), volatile and hygroscopic (V_H), and non-volatile and hygroscopic (NV_H) groups. Cluster analysis of wind direction and air mass backward trajectory have revealed that enhanced ultrafine particle concentrations were often observed when air mass was transported with high wind speed (>3 m s -1) from the polluted northeast region containing a significant amount of SO 2 and experienced a strong photochemical activity. We found the photochemically-produced ultrafine particles to consist primarily of NV_H with a little V_NH and V_H. In morning traffic events, we estimated ultrafine particles to consist of 61% NV_NH, 36% V (volatile group = the sum of V_NH and V_H), and 2% NV_H, while during biomass burning events, ultrafine particles consisted of 69% NV_NH, 21% V and 10% NV_H. Further, as determined by TEM/EDS analysis, the increase in NV_H during the biomass burning event was consistent with the frequent existence of K element in ultrafine particles. Comparison of data among different geometric locations in China and Korea revealed ultrafine particle hygroscopicity and volatility during the photochemical event as being highly variable in locations affected by diverse sources and variable precursor gases (e.g., SO 2 and VOC), while during the combustion events, less hygroscopicity variation across different locations was observed.

  10. Nanomaterials vs Ambient Ultrafine Particles

    DEFF Research Database (Denmark)

    Stone, Vicki; Miller, Mark R.; Clift, Martin J. D.

    2016-01-01

    BACKGROUND: A rich literature exists that has demonstrated adverse human health effects following exposure to ambient air particulate matter (PM), with strong support for an important role for ultrafine (nano-sized) particles. At present, relatively little human health or epidemiology data exists...

  11. Surgical smoke and ultrafine particles

    Directory of Open Access Journals (Sweden)

    Nowak Dennis

    2008-12-01

    Full Text Available Abstract Background Electrocautery, laser tissue ablation, and ultrasonic scalpel tissue dissection all generate a 'surgical smoke' containing ultrafine ( Methods To measure the amount of generated particulates in 'surgical smoke' during different surgical procedures and to quantify the particle number concentration for operation room personnel a condensation particle counter (CPC, model 3007, TSI Inc. was applied. Results Electro-cauterization and argon plasma tissue coagulation induced the production of very high number concentration (> 100000 cm-3 of particles in the diameter range of 10 nm to 1 μm. The peak concentration was confined to the immediate local surrounding of the production side. In the presence of a very efficient air conditioning system the increment and decrement of ultrafine particle occurrence was a matter of seconds, with accumulation of lower particle number concentrations in the operation room for only a few minutes. Conclusion Our investigation showed a short term very high exposure to ultrafine particles for surgeons and close assisting operating personnel – alternating with longer periods of low exposure.

  12. Efficiency of cloud condensation nuclei formation from ultrafine particles

    Directory of Open Access Journals (Sweden)

    J. R. Pierce

    2007-01-01

    Full Text Available Atmospheric cloud condensation nuclei (CCN concentrations are a key uncertainty in the assessment of the effect of anthropogenic aerosol on clouds and climate. The ability of new ultrafine particles to grow to become CCN varies throughout the atmosphere and must be understood in order to understand CCN formation. We have developed the Probability of Ultrafine particle Growth (PUG model to answer questions regarding which growth and sink mechanisms control this growth, how the growth varies between different parts of the atmosphere and how uncertainties with respect to the magnitude and size distribution of ultrafine emissions translates into uncertainty in CCN generation. The inputs to the PUG model are the concentrations of condensable gases, the size distribution of ambient aerosol, particle deposition timescales and physical properties of the particles and condensable gases. It was found in most cases that condensation is the dominant growth mechanism and coagulation with larger particles is the dominant sink mechanism for ultrafine particles. In this work we found that the probability of a new ultrafine particle generating a CCN varies from <0.1% to ~90% in different parts of the atmosphere, though in the boundary layer a large fraction of ultrafine particles have a probability between 1% and 40%. Some regions, such as the tropical free troposphere, are areas with high probabilities; however, variability within regions makes it difficult to predict which regions of the atmosphere are most efficient for generating CCN from ultrafine particles. For a given mass of primary ultrafine aerosol, an uncertainty of a factor of two in the modal diameter can lead to an uncertainty in the number of CCN generated as high as a factor for eight. It was found that no single moment of the primary aerosol size distribution, such as total mass or number, is a robust predictor of the number of CCN ultimately generated. Therefore, a complete description of the

  13. Particle number size distribution in the eastern Mediterranean: Formation and growth rates of ultrafine airborne atmospheric particles

    Science.gov (United States)

    Kopanakis, I.; Chatoutsidou, S. E.; Torseth, K.; Glytsos, T.; Lazaridis, M.

    2013-10-01

    Particle number concentration was measured between June 2009 and June 2010 at Akrotiri research station in a rural/suburban region of western Crete (Greece). Overall, the available data covered 157 days during the aforementioned period of measurements. The objectives were to study the number size distribution characteristics of ambient aerosols and furthermore to identify new particle formation events and to evaluate particle formation rates and growth rates of the newborn particles. Aerosol particles with mobility diameters between 10 and 1100 nm were measured using a Scanning Mobility Particle Sizer (SMPS) system. Measurements were performed at ambient relative humidities. The median total particle number concentration was 525 #/cm3 whereas the number concentration ranged between 130 #/cm3 and 9597 #/cm3. The average percentage of particles with diameters between 10 nm and 100 nm (N10-100) to total particles was 53% during summer and spring, but reached 80% during winter. Maximum average contribution of nano-particles (10 nm coagulation sinks. Mean growth and formation rates were calculated and showed values equal to 6 nm hr-1 and 13 cm-3 s-1, respectively.

  14. Exposure to ultrafine particles in asphalt work.

    Science.gov (United States)

    Elihn, Karine; Ulvestad, Bente; Hetland, Siri; Wallen, Anna; Randem, Britt Grethe

    2008-12-01

    An epidemiologic study has demonstrated that asphalt workers show increased loss of lung function and an increase of biomarkers of inflammation over the asphalt paving season. The aim of this study was to investigate which possible agent(s) causes the inflammatory reaction, with emphasis on ultrafine particles. The workers' exposure to total dust, polycyclic aromatic hydrocarbons, and NO(2) was determined by personal sampling. Exposure to ultrafine particles was measured by means of particle counters and scanning mobility particle sizer mounted on a van following the paving machine. The fractions of organic and elemental carbon were determined. Asphalt paving workers were exposed to ultrafine particles with medium concentration of about 3.4 x 10(4)/cm(3). Ultrafine particles at the paving site originated mainly from asphalt paving activities and traffic exhaust; most seemed to originate from asphalt fumes. Oil mist exceeded occupational limits on some occasions. Diesel particulate matter was measured as elemental carbon, which was low, around 3 microg/m(3). NO(2) and total dust did not exceed limits. Asphalt pavers were exposed to relatively high concentrations of ultrafine particles throughout their working day, with possible adverse health effects.

  15. Personal exposure to ultrafine particles.

    Science.gov (United States)

    Wallace, Lance; Ott, Wayne

    2011-01-01

    Personal exposure to ultrafine particles (UFP) can occur while people are cooking, driving, smoking, operating small appliances such as hair dryers, or eating out in restaurants. These exposures can often be higher than outdoor concentrations. For 3 years, portable monitors were employed in homes, cars, and restaurants. More than 300 measurement periods in several homes were documented, along with 25 h of driving two cars, and 22 visits to restaurants. Cooking on gas or electric stoves and electric toaster ovens was a major source of UFP, with peak personal exposures often exceeding 100,000 particles/cm³ and estimated emission rates in the neighborhood of 10¹² particles/min. Other common sources of high UFP exposures were cigarettes, a vented gas clothes dryer, an air popcorn popper, candles, an electric mixer, a toaster, a hair dryer, a curling iron, and a steam iron. Relatively low indoor UFP emissions were noted for a fireplace, several space heaters, and a laser printer. Driving resulted in moderate exposures averaging about 30,000 particles/cm³ in each of two cars driven on 17 trips on major highways on the East and West Coasts. Most of the restaurants visited maintained consistently high levels of 50,000-200,000 particles/cm³ for the entire length of the meal. The indoor/outdoor ratios of size-resolved UFP were much lower than for PM₂.₅ or PM₁₀, suggesting that outdoor UFP have difficulty in penetrating a home. This in turn implies that outdoor concentrations of UFP have only a moderate effect on personal exposures if indoor sources are present. A time-weighted scenario suggests that for typical suburban nonsmoker lifestyles, indoor sources provide about 47% and outdoor sources about 36% of total daily UFP exposure and in-vehicle exposures add the remainder (17%). However, the effect of one smoker in the home results in an overwhelming increase in the importance of indoor sources (77% of the total).

  16. Ultrafine particle exposure in Danish residencies

    DEFF Research Database (Denmark)

    Bekö, Gabriel; Karottki, Dorina Gabriela; Wierzbicka, Aneta

    2016-01-01

    We measured ultrafine particle concentrations in 56 Danish residences, estimated the daily integrated exposure of the occupants and apportioned this exposure to source events. The residential daily integrated particle number (PN) exposure in the homes was substantial and source events, especially...

  17. A chemical analyzer for charged ultrafine particles

    Directory of Open Access Journals (Sweden)

    S. G. Gonser

    2013-04-01

    Full Text Available New particle formation is a frequent phenomenon in the atmosphere and of major significance for the earth's climate and human health. To date the mechanisms leading to the nucleation of particles as well as to aerosol growth are not completely understood. A lack of appropriate measurement equipment for online analysis of the chemical composition of freshly nucleated particles is one major limitation. We have developed a Chemical Analyzer for Charged Ultrafine Particles (CAChUP capable of analyzing particles with diameters below 30 nm. A bulk of size separated particles is collected electrostatically on a metal filament, resistively desorbed and consequently analyzed for its molecular composition in a time of flight mass spectrometer. We report of technical details as well as characterization experiments performed with the CAChUP. Our instrument was tested in the laboratory for its detection performance as well as for its collection and desorption capabilities. The manual application of known masses of camphene (C10H16 to the desorption filament resulted in a detection limit between 0.5 and 5 ng, and showed a linear response of the mass spectrometer. Flow tube experiments of 25 nm diameter secondary organic aerosol from ozonolysis of alpha-pinene also showed a linear relation between collection time and the mass spectrometer's signal intensity. The resulting mass spectra from the collection experiments are in good agreement with published work on particles generated by the ozonolysis of alpha-pinene. A sensitivity study shows that the current setup of CAChUP is ready for laboratory measurements and for the observation of new particle formation events in the field.

  18. A chemical analyzer for charged ultrafine particles

    Directory of Open Access Journals (Sweden)

    S. G. Gonser

    2013-09-01

    Full Text Available New particle formation is a frequent phenomenon in the atmosphere and of major significance for the Earth's climate and human health. To date the mechanisms leading to the nucleation of particles as well as to aerosol growth are not completely understood. A lack of appropriate measurement equipment for online analysis of the chemical composition of freshly nucleated particles is one major limitation. We have developed a Chemical Analyzer for Charged Ultrafine Particles (CAChUP capable of analyzing particles with diameters below 30 nm. A bulk of size-separated particles is collected electrostatically on a metal filament, resistively desorbed and subsequently analyzed for its molecular composition in a time of flight mass spectrometer. We report on technical details as well as characterization experiments performed with the CAChUP. Our instrument was tested in the laboratory for its detection performance as well as for its collection and desorption capabilities. The manual application of defined masses of camphene (C10H16 to the desorption filament resulted in a detection limit between 0.5 and 5 ng, and showed a linear response of the mass spectrometer. Flow tube experiments of 25 nm diameter secondary organic aerosol from ozonolysis of alpha-pinene also showed a linear relation between collection time and the mass spectrometer's signal intensity. The resulting mass spectra from the collection experiments are in good agreement with published work on particles generated by the ozonolysis of alpha-pinene. A sensitivity study shows that the current setup of CAChUP is ready for laboratory measurements and for the observation of new particle formation events in the field.

  19. Emission of ultrafine particles from the incineration of municipal solid waste: A review

    Science.gov (United States)

    Jones, Alan M.; Harrison, Roy M.

    2016-09-01

    Ultrafine particles (diameter waste, and this article reviews studies carried out on the emissions from modern municipal waste incinerators. The effects of engineering controls upon particle emissions are considered, as well as the very limited information on the effects of changing waste composition. The results of measurements of incinerator flue gas, and of atmospheric sampling at ground level in the vicinity of incinerators, show that typical ultrafine particle concentrations in flue gas are broadly similar to those in urban air and that consequently, after the dispersion process dilutes incinerator exhaust with ambient air, ultrafine particle concentrations are typically indistinguishable from those that would occur in the absence of the incinerator. In some cases the ultrafine particle concentration in the flue gas may be below that in the local ambient air. This appears to be a consequence of the removal of semi-volatile vapours in the secondary combustion zone and abatement plant, and the high efficiency of fabric filters for ultrafine particle collection.

  20. Specific Property of Ultrafine Particle Classification

    Institute of Scientific and Technical Information of China (English)

    LI Guo-hua; HUANG Zhi-chu; ZHANG You-lin

    2003-01-01

    In the process of ultrafine particle classification,the separation curve,which reflects the characteristics of separating process,is frequently influenced by the characteristics of separation flow field and operating parameters,etc.This paper introduces the concept of system deviation and deduces the calculating method of the separation curves.Meanwhile,it analyses the influences of classification flow field's specific properties and some operating parameters on the separation curves.The results show that,in the process of ultrafine particle classification,the local vortex in the separation field improves the separation efficiency to a certain degree,but the accuracy will decrease;the coacervation action of particles will seriously influence the classification accuracy.

  1. Concentrated ambient ultrafine particle exposure induces cardiac change in young healthy volunteers

    Science.gov (United States)

    Exposure to ambient ultrafine particles has been associated with cardiopulmonary toxicity and mortality. Adverse effects specifically linked to ultrafine particles include loss of sympathovagal balance and altered hemostasis. To characterize the effects of ultrafine particles in ...

  2. Characterization of ultrafine and fine particles from CHP Plants

    Energy Technology Data Exchange (ETDEWEB)

    2009-08-15

    Samples of particles collected at CHP plants in the project 'Survey of emissions from CHP Plants' have been analysed in this project to give information on the morphology and chemical composition of individual particle size classes. The objective of this project was to characterize ultrafine and fine particles emitted to the atmosphere from Danish CHP plants. Nine CHP plants were selected in the Emission Survey Project as being representative for the different types of CHP plants operating in Denmark: 1) Three Waste-to Energy (WTE) plants. 2) Three biomass fired (BM) plants (two straw fired, one wood/saw dust fired). 3) Two gas fired (GF) plants (one natural gas, one landfill gas fired). 4) One gasoil (GO) fired plant. At the WTE and BM plants, various types of emission control systems implemented. The results from these plants represent the composition and size distribution of combustion particles that are emitted from the plants emission control systems. The measured emissions of particles from the waste-to-energy plants WTE1-3 are generally very low. The number and mass concentrations of ultrafine particles (PM{sub 0.1}) were particularly low in the flue gas from WTE2 and WTE3, where bag filters are used for the reduction of particle emissions. The EDX analysis of particles from the WTE plants indicates that the PM{sub 0.1} that penetrates the ECS at WTE can contain high fractions of metals such as Fe, Mn and Cu. The SEM analysis of particles from WTE1-3 showed that the particles were generally porous and irregular in shape. The concentrations of particles in the flue gas from the biomass plants were generally higher than found for the WTE plants. The time series results showed that periodical, high concentration peaks of PM emissions occur from BM1 and BM2. The chemical composition of the particles emitted from the three biomass plants is generally dominated by C, O and S, and to some extend also Fe and Si. A high amount of Cu was found in selected

  3. Preparation of ultrafine chitosan particles by reverse microemulsion

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Ultrafine chitosan particles were prepared by reverse microemulsion consisting of water, Triton X-100, octanol and cyclohexane. Two methods of preparing ultrafine chitosan particles were adopted and compared using TEM and IR, and possible mechanisms for the formation of ultrafine chitosan particles were proposed. Experimental results show that the method which combined ionic gelation and cross-linking gave uniformly sized chitosan nanoparticles with an average diameter of 92 nm, while the cross-linking without ionic gelation produced spindly chitosan particles with an average length of 943 nm and width of 188 nm.

  4. Surface magnetism of ferromagnetic ultrafine particles

    Institute of Scientific and Technical Information of China (English)

    ZHEN; Peng(甄鹏); LI; Hua(李华); HU; Weijun(胡维军); MEI; Liangmo(梅良模)

    2002-01-01

    The electronic structures and atomic magnetic moments of Nin clusters ( n = 2-6) have been studied. Compared with crystalline nickel, some clusters increase obviously in magnetism; some decrease obviously; and some show ferrimagnetism. The symmetry of clusters has great effect on magnetic moment. If they are similar in symmetry, the clusters are similar in magnetic moment. The magnetic moment for small clusters does not seem to increase or decrease monotonically with the change in their size, because adding or removing one atom may fully change the symmetry of small clusters. As the surface layer of ultrafine particles is made of many different polyhedrons with low symmetry and the alignment of the polyhedrons is complicated, the whole surface layer presents shortrange order. The calculated results explain the abnormal phenomena about surface magnetism that have been in existence for a long time.

  5. Ultrafine particle measurement and related EPA research studies

    Science.gov (United States)

    Webinar slides to present information on measuring ultrafine particles at the request of the 2013 MARAMA Monitoring Committee. The talk covers near-road monitoring, instrument intercomparison, and general overview of UFP monitoring technology.

  6. Separation of ultrafine particles from class F fly ashes

    Directory of Open Access Journals (Sweden)

    Acar Ilker

    2016-01-01

    Full Text Available In this study, ultrafine particles were recovered from Çatalağzı (CFA and Sugözü (SFA thermal power plant fly ashes using a specific hydraulic classification technology. Since fly ashes have a high tendency to be flocculated in water, settling experiments were first designed to determine the more effective dispersant and the optimum dosage. Two different types of the superplasticizers (SP polymers based on sulphonate (NSF, Disal and carboxylate (Glenium 7500 were used as the dispersing agents in these settling experiments. Hydraulic classification experiments were then conducted to separate ultrafine fractions from the fly ash samples on the basis of the settling experiments. According to the settling experiments, better results were achieved with the use of Disal for both CFA and SFA. The classification experiments showed that the overflow products with average particle sizes of 5.2 μm for CFA and 4.4 μm for SFA were separated from the respective as-received samples with acceptable yields and high enough recoveries of -5 μm (ultrafine particles. Overall results pointed out that the hydraulic classification technology used provided promising results in the ultrafine particle separations from the fly ash samples.

  7. Outdoor ultrafine particle concentrations in front of fast food restaurants

    NARCIS (Netherlands)

    Vert, Cristina; Meliefste, Kees; Hoek, Gerard

    2016-01-01

    Ultrafine particles (UFPs) have been associated with negative effects on human health. Emissions from motor vehicles are the principal source of UFPs in urban air. A study in Vancouver suggested that UFP concentrations were related to density of fast food restaurants near the monitoring sites. A pre

  8. Worker exposure to ultrafine particles during carbon black treatment

    Directory of Open Access Journals (Sweden)

    Urszula Mikołajczyk

    2015-07-01

    Full Text Available Background: The aim of the project was to assess the exposure of workers to ultrafine particles released during handling and packing of carbon black. The assessment included the results of the measurements performed in a carbon black handling plant before, during, and after work shift. Material and Methods: The number concentration of particles within the dimension range 10–1000 nm and 10–100 nm was assayed by a condensation particle counter (CPC. The mass concentration of particles was determined by a DustTrak II DRX aerosol concentration monitor. The surface area concentration of the particles potentially deposited in the alveolar (A and tracheo-bronchial (TB regions was estimated by an AeroTrak 9000 nanoparticle monitor. Results: An average mass concentration of particles during the process was 6-fold higher than that before its start, while a 3-fold increase in the average number concentration of particles within the dimension range 10–1000 nm and 10–100 nm was observed during the process. At the same time a 4-fold increase was found in the surface area concentration of the particles potentially deposited in the A and TB regions. Conclusions: During the process of carbon black handling and packing a significantly higher values of each of the analysed parameters, characterizing the exposure to ultrafine particles, were noted. Med Pr 2015;66(3:317–326

  9. Aerosol number size distributions over a coastal semi urban location: Seasonal changes and ultrafine particle bursts

    Energy Technology Data Exchange (ETDEWEB)

    Babu, S. Suresh, E-mail: s_sureshbabu@vssc.gov.in [Space Physics Laboratory, Vikram Sarabhai Space Centre, Thiruvananthapuram 695022 (India); Kompalli, Sobhan Kumar [Space Physics Laboratory, Vikram Sarabhai Space Centre, Thiruvananthapuram 695022 (India); Moorthy, K. Krishna [Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science, Bangalore 560 012 (India)

    2016-09-01

    Number-size distribution is one of the important microphysical properties of atmospheric aerosols that influence aerosol life cycle, aerosol-radiation interaction as well as aerosol-cloud interactions. Making use of one-yearlong measurements of aerosol particle number-size distributions (PNSD) over a broad size spectrum (~ 15–15,000 nm) from a tropical coastal semi-urban location-Trivandrum (Thiruvananthapuram), the size characteristics, their seasonality and response to mesoscale and synoptic scale meteorology are examined. While the accumulation mode contributed mostly to the annual mean concentration, ultrafine particles (having diameter < 100 nm) contributed as much as 45% to the total concentration, and thus constitute a strong reservoir, that would add to the larger particles through size transformation. The size distributions were, in general, bimodal with well-defined modes in the accumulation and coarse regimes, with mode diameters lying in the range 141 to 167 nm and 1150 to 1760 nm respectively, in different seasons. Despite the contribution of the coarse sized particles to the total number concentration being meager, they contributed significantly to the surface area and volume, especially during transport of marine air mass highlighting the role of synoptic air mass changes. Significant diurnal variation occurred in the number concentrations, geometric mean diameters, which is mostly attributed to the dynamics of the local coastal atmospheric boundary layer and the effect of mesoscale land/sea breeze circulation. Bursts of ultrafine particles (UFP) occurred quite frequently, apparently during periods of land-sea breeze transitions, caused by the strong mixing of precursor-rich urban air mass with the cleaner marine air mass; the resulting turbulence along with boundary layer dynamics aiding the nucleation. These ex-situ particles were observed at the surface due to the transport associated with boundary layer dynamics. The particle growth rates from

  10. Concentrations of ultrafine particles at a highway toll collection booth and exposure implications for toll collectors.

    Science.gov (United States)

    Cheng, Yu-Hsiang; Huang, Cheng-Hsiung; Huang, Hsiao-Lin; Tsai, Chuen-Jinn

    2010-12-15

    Research regarding the magnitude of ultrafine particle levels at highway toll stations is limited. This study measured ambient concentrations of ultrafine particles at a highway toll station from October 30 to November 1 and November 5 to November 6, 2008. A scanning mobility particle sizer was used to measure ultrafine particle concentrations at a ticket/cash tollbooth. Levels of hourly average ultrafine particles at the tollbooth were about 3-6 times higher than those in urban backgrounds, indicating that a considerable amount of ultrafine particles are exhausted from passing vehicles. A bi-modal size distribution pattern with a dominant mode at about particle reactions in fresh fumes emitted directly from vehicles. The influences of traffic volume, wind speed, and relative humidity on ultrafine particle concentrations were also determined. High ambient concentrations of ultrafine particles existed under low wind speed, low relative humidity, and high traffic volume. Although different factors account for high ambient concentrations of ultrafine particles at the tollbooth, measurements indicate that toll collectors who work close to traffic emission sources have a high exposure risk.

  11. Anti-aggregation dispersion of ultrafine particles by electro-static technique

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The dispersion of ultrafine particles in the air can be achieved by mechanical method or surface modification. In this work, the electrostatic technique was first employed for anti-aggregation of ultrafine particles. When the relative humidity of the air is within the region of 70%-75%, effective storage time of ultrafine particles can reach 72 h after treatment by the electrostatic technique. The experi-mental results showed that this technique imparted ultrafine particles much more pronounced anti-aggregation property. In the dry air, the critical diameter of ultrafine particles anti-aggregated by the electrostatic technique is the function of particle property and charging field intensity. The critical diameter is inversely proportional to the square of the charging field intensity.

  12. Exposure to inhalable, respirable, and ultrafine particles in welding fume.

    Science.gov (United States)

    Lehnert, Martin; Pesch, Beate; Lotz, Anne; Pelzer, Johannes; Kendzia, Benjamin; Gawrych, Katarzyna; Heinze, Evelyn; Van Gelder, Rainer; Punkenburg, Ewald; Weiss, Tobias; Mattenklott, Markus; Hahn, Jens-Uwe; Möhlmann, Carsten; Berges, Markus; Hartwig, Andrea; Brüning, Thomas

    2012-07-01

    This investigation aims to explore determinants of exposure to particle size-specific welding fume. Area sampling of ultrafine particles (UFP) was performed at 33 worksites in parallel with the collection of respirable particles. Personal sampling of respirable and inhalable particles was carried out in the breathing zone of 241 welders. Median mass concentrations were 2.48 mg m(-3) for inhalable and 1.29 mg m(-3) for respirable particles when excluding 26 users of powered air-purifying respirators (PAPRs). Mass concentrations were highest when flux-cored arc welding (FCAW) with gas was applied (median of inhalable particles: 11.6 mg m(-3)). Measurements of particles were frequently below the limit of detection (LOD), especially inside PAPRs or during tungsten inert gas welding (TIG). However, TIG generated a high number of small particles, including UFP. We imputed measurements welding fume. Concentrations were mainly predicted by the welding process and were significantly higher when local exhaust ventilation (LEV) was inefficient or when welding was performed in confined spaces. Substitution of high-emission techniques like FCAW, efficient LEV, and using PAPRs where applicable can reduce exposure to welding fume. However, harmonizing the different exposure metrics for UFP (as particle counts) and for the respirable or inhalable fraction of the welding fume (expressed as their mass) remains challenging.

  13. [Ultrafine particles and effects on the body: review of the literature].

    Science.gov (United States)

    Pedata, P; Garzillo, E M; Sannolo, N

    2010-01-01

    The International laws and the technology developments led to a situation where the current levels of environmental pollution are below those that existed at the beginning of the century: however, these pollution levels produce harmful effects to health linked to an increase in morbidity and mortality. Over the years the pollution has changed: following the transformation of heating, motor innovation and emissions reducing, has been a reduction in air concentration of some conventional pollutants (sulfur dioxide, carbon monoxide, benzene), while there wasn't a significant reduction of particulate air pollution. In this work have been questioned several electronic databases of scientific literature based on a selection algorithm that contains expressions for the following topics: "ultrafine particles", "effects on human health", "occupational and environmental exposure". We analyzed 200 articles, progressively reduced to 88, selected for keywords, year of publication and arguments; the main topics covered by the articles were related to chemical and physical UFP properties, UFP exposure, European legislation relating to the values of particle concentrations in the atmosphere, toxicokinetics and effects on various organs such as, in particular, the respiratory system, cardiovascular system, central nervous system and the intracellular mechanism of action. Analysis of the literature showed that ultrafine particles (PM0.1 aerodynamic diameter less than 0.1 microm) are more powerful than the coarse particle fraction (2.5-10 microm) and fine (0.1-2.5 microm) in inducing adverse effects to human health. Unfortunately, the study of mechanisms of action of these particles presents particular difficulties because of the large number of chemical and biological mechanisms that come into play in the body after exposure to ultrafine particles.

  14. Monte Carlo N-Particle Tracking of Ultrafine Particle Flow in Bent Micro-Tubes

    Energy Technology Data Exchange (ETDEWEB)

    Casella, Andrew M.; Loyalka, Sudarsham K.

    2016-02-16

    The problem of large pressure-differential driven laminar convective-diffusive ultrafine aerosol flow through bent micro-tubes is of interest in several contemporary research areas including; release of contents from pressurized containment vessels, aerosol sampling equipment, advanced scientific instruments, gas-phase micro-heat exchangers, and microfluidic devices. In each of these areas, the predominant problem is the determination of the fraction of particles entering the micro-tube that is deposited within the tube and the fraction that is transmitted through. Due to the extensive parameter restrictions of this class of problems, a Lagrangian particle tracking method making use of the coupling of the analytical stream line solutions of Dean and the simplified Langevin equation is quite a useful tool in problem characterization. This method is a direct analog to the Monte Carlo N-Particle method of particle transport extensively used in nuclear physics and engineering. In this work, 10 nm diameter particles with a density of 1 g/cm3 are tracked within micro-tubes with toroidal bends with pressure differentials ranging between 0.2175 and 0.87 atmospheres. The tubes have radii of 25 microns and 50 microns and the radius of curvature is between 1 m and 0.3183 cm. The carrier gas is helium, and temperatures of 298 K and 558 K are considered. Numerical convergence is considered as a function of time step size and of the number of particles per simulation. Particle transmission rates and deposition patterns within the bent micro-tubes are calculated.

  15. Exposure to ultrafine and fine particles and noise during cycling and driving in 11 Dutch cities

    NARCIS (Netherlands)

    Boogaard, H.; Borgman, G.; Kamminga, J.; Hoek, H.

    2009-01-01

    Recent studies have suggested that exposures during traffic participation may be associated with adverse health effects. Traffic participation involves relatively short but high exposures. Potentially relevant exposures include ultrafine particles, fine particles (PM2.5) and noise. Simultaneously, d

  16. Filtration efficiency of an electrostatic fibrous filter: Studying filtration dependency on ultrafine particle exposure and composition

    DEFF Research Database (Denmark)

    Ardkapan, Siamak Rahimi; Johnson, Matthew S.; Yazdi, Sadegh

    2014-01-01

    The objective of the present study is to investigate the relationship between ultrafine particle concentrations and removal efficiencies for an electrostatic fibrous filter in a laboratory environment. Electrostatic fibrous filters capture particles efficiently, with a low pressure drop. Therefor...

  17. Vascular effects of ultrafine particles in persons with type 2 diabetes

    Science.gov (United States)

    BACKGROUND: Diabetes confers an increased risk for cardiovascular effects of airborne particles. OBJECTIVE: We hypothesized that inhalation of elemental carbon ultrafine particles (UFP) would activate blood platelets and vascular endothelium in people with type 2 diabetes. ...

  18. Separation of Fischer-Tropsch Wax Products from Ultrafine Iron Catalyst Particles

    Energy Technology Data Exchange (ETDEWEB)

    James K. Neathery; Gary Jacobs; Amitava Sarkar; Adam Crawford; Burtron H. Davis

    2006-09-30

    In the previous reporting period, modifications were completed for integrating a continuous wax filtration system for a 4 liter slurry bubble column reactor. During the current reporting period, a shakedown of the system was completed. Several problems were encountered with the progressive cavity pump used to circulate the wax/catalyst slurry though the cross-flow filter element and reactor. During the activation of the catalyst with elevated temperature (> 270 C) the elastomer pump stator released sulfur thereby totally deactivating the iron-based catalyst. Difficulties in maintaining an acceptable leak rate from the pump seal and stator housing were also encountered. Consequently, the system leak rate exceeded the expected production rate of wax; therefore, no online filtration could be accomplished. Work continued regarding the characterization of ultra-fine catalyst structures. The effect of carbidation on the morphology of iron hydroxide oxide particles was the focus of the study during this reporting period. Oxidation of Fe (II) sulfate results in predominantly {gamma}-FeOOH particles which have a rod-shaped (nano-needles) crystalline structure. Carbidation of the prepared {gamma}-FeOOH with CO at atmospheric pressure produced iron carbides with spherical layered structure. HRTEM and EDS analysis revealed that carbidation of {gamma}-FeOOH particles changes the initial nano-needles morphology and generates ultrafine carbide particles with irregular spherical shape.

  19. Recycling concrete: An undiscovered source of ultrafine particles

    Science.gov (United States)

    Kumar, Prashant; Morawska, Lidia

    2014-06-01

    While concrete recycling is practiced worldwide, there are many unanswered questions in relation to ultrafine particle (UFP; Dp recycling sites. In particular: (i) Does recycling produce UFPs and in what quantities? (ii) How do they disperse around the source? (iii) What impact does recycling have on ambient particle number concentrations (PNCs) and exposure? (iv) How effective are commonly used dust respirators to limit exposure? We measured size-resolved particles in the 5-560 nm range at five distances between 0.15 and 15.15 m that were generated by an experimentally simulated concrete recycling source and found that: (i) the size distributions were multimodal, with up to ˜93% of total PNC in the UFP size range; and (ii) dilution was a key particle transformation mechanism. UFPs showed a much slower decay rate, requiring ˜62% more distance to reach 10% of their initial concentration compared with their larger counterparts in the 100-560 nm size range. Compared with typical urban exposure during car journeys, exposure decay profiles showed up to ˜5 times higher respiratory deposition within 10 m of the source. Dust respirators were found to remove half of total PNC; however the removal factor for UFPs was only ˜57% of that observed in the 100-560 nm size range. These findings highlight a need for developing an understanding of the nature of the particles as well as for better control measures to limit UFP exposure.

  20. Forecasting ultrafine particle concentrations from satellite and in situ observations

    Science.gov (United States)

    Crippa, P.; Castruccio, S.; Pryor, S. C.

    2017-02-01

    Recent innovations in remote sensing technologies and retrievals offer the potential for predicting ultrafine particle (UFP) concentrations from space. However, the use of satellite observations to provide predictions of near-surface UFP concentrations is limited by the high frequency of incomplete predictor values (due to missing observations), the lack of models that account for the temporal dependence of UFP concentrations, and the large uncertainty in satellite retrievals. Herein we present a novel statistical approach designed to address the first two limitations. We estimate UFP concentrations by using lagged estimates of UFP and concurrent satellite-based observations of aerosol optical properties, ultraviolet solar radiation flux, and trace gas concentrations, wherein an expectation maximization algorithm is used to impute missing values in the satellite observations. The resulting model of UFP (derived by using an autoregressive moving average model with exogenous inputs) explains 51 and 28% of the day-to-day variability in concentrations at two sites in eastern North America.

  1. Synthesis of silicon carbide-silicon nitride composite ultrafine particles using a carbon dioxide laser

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Masaaki; Maniette, Yves; Nakata, Yoshinori; Okutani, Takeshi (Government Industrial Development Lab., Hokkaido, Sapporo (Japan))

    1993-05-01

    The synthesis and the structure of silicon carbide-silicon nitride (SiC-Si[sub 3]N[sub 4]) composite ultrafine particles have been studied. SiC-Si[sub 3]N[sub 4] composite ultrafine particles were prepared by irradiating a SiH[sub 4], C[sub 2]H[sub 4], and NH[sub 3] gas mixture with a CO[sub 2] laser at atmospheric pressure. The composition of composite powders changed with the reactant gas flow rate. The carbon and nitrogen content of the powder could be controlled in a wide range from 0 to 30 wt%. The composite powder, which contained 25.3 wt% carbon and 5.8 wt% nitrogen, had a [beta]-SiC structure. As the nitrogen content increased, SiC decreased and amorphous phase, Si[sub 3]N[sub 4], Si appeared. The results of XPS and lattice constant measurements suggested that Si, C, and N atoms were intimately mixed in the composite particles.

  2. Identification and verification of ultrafine particle affinity zones in urban neighbourhoods: sample design and data pre-processing.

    LENUS (Irish Health Repository)

    Harris, Paul

    2009-01-01

    A methodology is presented and validated through which long-term fixed site air quality measurements are used to characterise and remove temporal signals in sample-based measurements which have good spatial coverage but poor temporal resolution. The work has been carried out specifically to provide a spatial dataset of atmospheric ultrafine particle (UFP < 100 nm) data for ongoing epidemiologic cohort analysis but the method is readily transferable to wider epidemiologic investigations and research into the health effects of other pollutant species.

  3. Nanocapillary Atmospheric Pressure Plasma Jet: A Tool for Ultrafine Maskless Surface Modification at Atmospheric Pressure.

    Science.gov (United States)

    Motrescu, Iuliana; Nagatsu, Masaaki

    2016-05-18

    With respect to microsized surface functionalization techniques we proposed the use of a maskless, versatile, simple tool, represented by a nano- or microcapillary atmospheric pressure plasma jet for producing microsized controlled etching, chemical vapor deposition, and chemical modification patterns on polymeric surfaces. In this work we show the possibility of size-controlled surface amination, and we discuss it as a function of different processing parameters. Moreover, we prove the successful connection of labeled sugar chains on the functionalized microscale patterns, indicating the possibility to use ultrafine capillary atmospheric pressure plasma jets as versatile tools for biosensing, tissue engineering, and related biomedical applications.

  4. Ultrafine particles at eight urban sites in Antwerp. Instrument comparison and spatiotemporal variation in particle number concentration and size distribution

    Energy Technology Data Exchange (ETDEWEB)

    Staelens, J.; Matheeussen, C.; Roekens, E. [Department Air, Environment and Communication, Flemish Environment Agency VMM, Antwerp, 2000 (Belgium); Frijns, E.; Berghmans, P. [Flemish Institute for Technological Research VITO, Mol, 2400 (Belgium); Kos, G.P.A.; Weijers, E.P. [Environment and Energy Engineering, Energy research Centre of the Netherlands ECN, Petten, 1755 ZG (Netherlands); Panteliadis, P. [Department of Air Quality, Public Health Service ofAmsterdam, Amsterdam, 1000 CE (Netherlands); Bergmans, B. [Air Quality, Institut Scientifique de Service Public (ISSeP), Liege, 4000 (Belgium); Wyche, K. [Department of Chemistry, University of Leicester, Leicester, LE2 7TG (United Kingdom)

    2013-03-15

    Due to the short atmospheric lifetime of ultrafine particles (UFP) and their strong dependence on local sources, ambient particle number concentrations and size distributions may vary significantly on short spatial and temporal scales. Because UFP are a primary pollutant that is rapidly transformed by physicochemical processes (dispersion, coagulation, deposition, etc.) and emitted mainly by mobile sources, they show a very high spatial variation. The particle number concentration is known to be elevated near roads and to decrease with increasing distance to the road primarily as a result of dispersion. Therefore, UFP measurements at a single urban background air quality monitoring station may not be indicative of the actual exposure in the communities surrounding this station. To address this problem and to more accurately estimate human exposure and subsequent health impacts of UFP, more intensive measurements on finer spatial scales are needed. Therefore, UFP measurements were carried out at eight urban background or hotspot sites in the city of Antwerp (Belgium)

  5. Comparison of deposited surface area of airborne ultrafine particles generated from two welding processes.

    Science.gov (United States)

    Gomes, J F; Albuquerque, P C; Miranda, Rosa M; Santos, Telmo G; Vieira, M T

    2012-09-01

    This article describes work performed on the assessment of the levels of airborne ultrafine particles emitted in two welding processes metal-active gas (MAG) of carbon steel and friction-stir welding (FSW) of aluminium in terms of deposited area in alveolar tract of the lung using a nanoparticle surface area monitor analyser. The obtained results showed the dependence from process parameters on emitted ultrafine particles and clearly demonstrated the presence of ultrafine particles, when compared with background levels. The obtained results showed that the process that results on the lower levels of alveolar-deposited surface area is FSW, unlike MAG. Nevertheless, all the tested processes resulted in important doses of ultrafine particles that are to be deposited in the human lung of exposed workers.

  6. Fabrication of cast carbon steel with ultrafine TiC particles

    Institute of Scientific and Technical Information of China (English)

    Sang-Hoon LEE; Jin-Ju PARK; Sung-Mo HONG; Byoung-Sun HAN; Min-Ku LEE; Chang-Kyu RHEE

    2011-01-01

    The carbon steels dispersed with ultrafine TiC particles were fabricated by conventional casting method. The casting process is more economical than other available routes for metal matrix composite production, and the large sized components to be fabricated in short processing time. However, it is extremely difficult to obtain uniform dispersion of ultrafine ceramic particles in liquid metals due to the poor wettability and the specific gravity difference between the ceramic particle and metal matrix, In order to solve these problems, the mechanical milling (MM) and surface-active processes were introduced. As a result, Cu coated ultrafine TiC powders made by MM process using high energy ball milling machine were mixed with Sn powders as a surfactant to get better wettability by lowering the surface tension of carbon steel melt, The microstructural investigations by OM show that ultrafine TiC particles are distributed uniformly in carbon steel matrix. The grain sizes of the cast matrix with ultrafine TiC particles are much smaller than those without ultrafine TiC particles. This is probably due to the fact that TiC particles act as nucleation sites during solidification. The wear resistance of cast carbon steel composites added with MMed TiC/Cu-Sn powders is improved due to grain size refinement.

  7. Ultrafine particle removal and generation by portable air cleaners

    Science.gov (United States)

    Waring, Michael S.; Siegel, Jeffrey A.; Corsi, Richard L.

    Portable air cleaners can both remove and generate pollutants indoors. To investigate these phenomena, we conducted a two-phase investigation in a 14.75 m 3 stainless steel chamber. In the first phase, particle size-resolved (12.6-514 nm diameter) clean air delivery rates (CADR) and efficiencies were determined, as were ozone emission rates, for two high-efficiency particle arresting (HEPA) filters, one electrostatic precipitator with a fan, and two ion generators without fans. The two HEPA air cleaners had count average CADR (standard deviation) of 188 (30) and 324 (44) m 3 h -1; the electrostatic precipitator 284 (62) m 3 h -1; and the two ion generators 41 (11) and 35 (13) m 3 h -1. The electrostatic precipitator emitted ozone at a rate of 3.8±0.2 mg h -1, and the two ion generators 3.3±0.2 and 4.3±0.2 mg h -1. Ozone initiates reactions with certain unsaturated organic compounds that produce ultrafine and fine particles, carbonyls, other oxidized products, and free radicals. During the second phase, five different ion generators were operated separately in the presence of a plug-in liquid or solid air freshener, representing a strong terpene source. For air exchange rates of between 0.49 and 0.96 h -1, three ion generators acted as steady-state net particle generators in the entire measured range of 4.61-157 nm, and two generated particles in the range of approximately 10 to 39-55 nm. Terpene and aldehyde concentrations were also sampled for one ion generator, and concentrations of terpenes decreased and formaldehyde increased. Given these results, the pollutant removal benefits of ozone-generating air cleaners may be outweighed by the generation of indoor pollution.

  8. Outdoor ultrafine particle concentrations in front of fast food restaurants.

    Science.gov (United States)

    Vert, Cristina; Meliefste, Kees; Hoek, Gerard

    2016-01-01

    Ultrafine particles (UFPs) have been associated with negative effects on human health. Emissions from motor vehicles are the principal source of UFPs in urban air. A study in Vancouver suggested that UFP concentrations were related to density of fast food restaurants near the monitoring sites. A previous monitoring campaign could not separate the contribution of restaurants from road traffic. The main goal of this study has been the quantification of fast food restaurants' contribution to outdoor UFP concentrations. A portable particle number counter (DiscMini) has been used to carry out mobile monitoring in a largely pedestrianized area in the city center of Utrecht. A fixed route passing 17 fast food restaurants was followed on 8 days. UFP concentrations in front of the restaurants were 1.61 times higher than in a nearby square without any local sources used as control area and 1.22 times higher compared with all measurements conducted in between the restaurants. Adjustment for other sources such as passing mopeds, smokers or candles did not explain the increase. In conclusion, fast food restaurants result in significant increases in outdoor UFP concentrations in front of the restaurant.

  9. Measurements of Ultra-fine and Fine Aerosol Particles over Siberia: Large-scale Airborne Campaigns

    Science.gov (United States)

    Arshinov, Mikhail; Paris, Jean-Daniel; Stohl, Andreas; Belan, Boris; Ciais, Philippe; Nédélec, Philippe

    2010-05-01

    In this paper we discuss the results of in-situ measurements of ultra-fine and fine aerosol particles carried out in the troposphere from 500 to 7000 m in the framework of several International and Russian State Projects. Number concentrations of ultra-fine and fine aerosol particles measured during intensive airborne campaigns are presented. Measurements carried over a great part of Siberia were focused on particles with diameters from 3 to 21 nm to study new particle formation in the free/upper troposphere over middle and high latitudes of Asia, which is the most unexplored region of the Northern Hemisphere. Joint International airborne surveys were performed along the following routes: Novosibirsk-Salekhard-Khatanga-Chokurdakh-Pevek-Yakutsk-Mirny-Novosibirsk (YAK-AEROSIB/PLARCAT2008 Project) and Novosibirsk-Mirny-Yakutsk-Lensk-Bratsk-Novosibirsk (YAK-AEROSIB Project). The flights over Lake Baikal was conducted under Russian State contract. Concentrations of ultra-fine and fine particles were measured with automated diffusion battery (ADB, designed by ICKC SB RAS, Novosibirsk, Russia) modified for airborne applications. The airborne ADB coupled with CPC has an additional aspiration unit to compensate ambient pressure and changing flow rate. It enabled to classify nanoparticles in three size ranges: 3-6 nm, 6-21 nm, and 21-200 nm. To identify new particle formation events we used similar specific criteria as Young et al. (2007): (1) N3-6nm >10 cm-3, (2) R1=N3-6/N621 >1 and R2=N321/N21200 >0.5. So when one of the ratios R1 or R2 tends to decrease to the above limits the new particle formation is weakened. It is very important to notice that space scale where new particle formation was observed is rather large. All the events revealed in the FT occurred under clean air conditions (low CO mixing ratios). Measurements carried out in the atmospheric boundary layer over Baikal Lake did not reveal any event of new particle formation. Concentrations of ultra-fine

  10. Ultrafine particle size as a tracer for aircraft turbine emissions.

    Science.gov (United States)

    Riley, Erin A; Gould, Timothy; Hartin, Kris; Fruin, Scott A; Simpson, Christopher D; Yost, Michael G; Larson, Timothy

    2016-08-01

    Ultrafine particle number (UFPN) and size distributions, black carbon, and nitrogen dioxide concentrations were measured downwind of two of the busiest airports in the world, Los Angeles International Airport (LAX) and Hartsfield-Jackson International Airport (ATL - Atlanta, GA) using a mobile monitoring platform. Transects were located between 5 km and 10 km from the ATL and LAX airports. In addition, measurements were taken at 43 additional urban neighborhood locations in each city and on freeways. We found a 3-5 fold increase in UFPN concentrations in transects under the landing approach path to both airports relative to surrounding urban areas with similar ground traffic characteristics. The latter UFPN concentrations measured were distinct in size distributional properties from both freeways and across urban neighborhoods, clearly indicating different sources. Elevated concentrations of Black Carbon (BC) and NO2 were also observed on airport transects, and the corresponding pattern of elevated BC was consistent with the observed excess UFPN concentrations relative to other urban locations.

  11. Ultrafine particle air pollution inside diesel-propelled passenger trains.

    Science.gov (United States)

    Abramesko, Victoria; Tartakovsky, Leonid

    2017-04-05

    Locomotives with diesel engines are used worldwide and are an important source of air pollution. Pollutant emissions by locomotive engines affect the air quality inside passenger trains. This study is aimed at investigating ultrafine particle (UFP) air pollution inside passenger trains and providing a basis for assessing passenger exposure to this pollutant. The concentrations of UFPs inside the carriages of push-pull trains are dramatically higher when the train operates in pull mode. This clearly shows that locomotive engine emissions are a dominant factor in train passengers' exposure to UFPs. The highest levels of UFP air pollution are observed inside the carriages of pull trains close to the locomotive. In push mode, the UFP number concentrations were lower by factors of 2.6-43 (depending on the carriage type) compared to pull mode. The UFP concentrations are substantially lower in diesel multiple-unit trains than in trains operating in pull mode. A significant influence of the train movement regime on the UFP NC inside a carriage is observed.

  12. Study of real time detection and size distribution measurement of ultrafine aerosol with a particle growth system (PGS)

    Energy Technology Data Exchange (ETDEWEB)

    Rebours, A.

    1994-06-29

    First, the theoretical knowledge on condensation phenomena of a supersaturated vapor in a cylindrical duct where an ultrafine aerosol of nanometers size is flowing, is recalled. Then, a Particle Growth-System (PGS) of original design is developed: the aerosol is confined in a region with a uniform vapor supersaturation profile. When imperfectly filtered atmospheric air is used as source of condensation nuclei, the produced droplets are found to be monodisperse. Therefore, our PGS offers a simple method of calibrating Optical Particle Counters because the size distribution of theses droplets is controlled. After an experimental study validated by a theoretical model, we establish that, under certain supersaturation conditions, the droplet size in our PGS is a function of ultrafine particle size on which the vapor condenses. Furthermore, when the sampled aerosol is constituted of an ultrafine fraction and a fine fraction, we show that the size distribution of the droplets that come out from the PGS is bimodal too. Finally, a simple redesign of our fluids inlet system should reduce particles losses in the PGS due to brownian diffusion and, in that manner improve their detection. (author). 72 refs., 46 figs., 8 tabs., 4 appends.

  13. What does respirator certification tell us about filtration of ultrafine particles?

    Science.gov (United States)

    Eninger, Robert M; Honda, Takeshi; Reponen, Tiina; McKay, Roy; Grinshpun, Sergey A

    2008-05-01

    Recent interest in exposures to ultrafine particles (less than 100 nm) in both environmental and occupational settings led the authors to question whether the protocols used to certify respirator filters provide adequate attention to ultrafine aerosols. The authors reviewed the particle size distribution of challenge aerosols and evaluated the aerosol measurement method currently employed in the National Institute for Occupational Safety and Health (NIOSH) particulate respirator certification protocol for its ability to measure the contribution of ultrafine particles to filter penetration. Also considered were the differences between mechanical and electrically charged (electret) filters in light of the most penetrating particle size. It was found that the sodium chloride (NaCl) and dioctylphthalate (DOP) aerosols currently used in respirator certification tests contain a significant fraction of particles in the ultrafine region. However, the photometric method deployed in the certification test is not capable of adequately measuring light scatter of particles below approximately 100 nm in diameter. Specifically, 68% (by count) and 8% (by mass) of the challenge NaCl aerosol particles and 10% (by count) and 0.3% (by mass) of the DOP particles below 100 nm do not significantly contribute to the filter penetration measurement. In addition, the most penetrating particle size for electret filters likely occurs at 100 nm or less under test conditions similar to those used in filter certification. The authors conclude, therefore, that the existing NIOSH certification protocol may not represent a worst-case assessment for electret filters because it has limited ability to determine the contribution of ultrafine aerosols, which include the most penetrating particle size for electret filters. Possible strategies to assess ultrafine particle penetration in the certification protocol are discussed.

  14. Mammalian cell-transforming potential of traffic-linked ultrafine particulate matter PM0.056 in urban roadside atmosphere.

    Science.gov (United States)

    Verma, Mukesh K; Poojan, Shiv; Sultana, Sarwat; Kumar, Sushil

    2014-09-01

    We examined the clastogenic and cell-transforming potential of ultrafine particulate matter fraction PM0.056 of urban ambient aerosol using mammalian cells. PM1.0, PM0.56 and PM0.056 fractions were sampled from roadside atmosphere of an urban area using the cascade impactor MOUDI-NR-110. The potential to induce cytotoxicity, DNA damage and micronuclei formation was examined at the test concentrations of 3, 6, 12.5, 25, 50 and 100 μg/ml using the 3-4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, the plasmid relaxation assay and the C3H10T1/2 (10T1/2) cells. The cell-transforming potential was investigated in vitro using 10T1/2 cell transformation assay and the soft agar assay. PM1, PM0.56 and PM0.056 fractions were found to be toxic in dose-dependent manner. These induced cytotoxicity at five test concentrations, the ultrafine particle fraction PM0.056 showed greater cytotoxic potential. PM0.056 induced micronucleus formation in 10T1/2 cells. The effect was statistically significant. The DNA-damaging potential was measured in a plasmid relaxation assay. Both fine and ultrafine particle fraction PM0.56 and PM0.056 displayed greater effect as compared to larger PM1 fraction. DNA damage was found to be dependent on particulate matter intrinsic pro-oxidant chemicals. The ability of the ultrafine particle fraction PM0.056 to induce morphological cell transformation was demonstrated by significant and dose-dependent increases in type III focus formation by morphologically transformed cells in culture flasks and their clonal expansion in soft agar. It is concluded that the traffic-linked ultrafine particle fraction PM0.056 in the atmosphere by the roadside of an urban area is clastogenic and able to induce morphological transformation of mammalian cells.

  15. A mechanism for the production of ultrafine particles from concrete fracture.

    Science.gov (United States)

    Jabbour, Nassib; Rohan Jayaratne, E; Johnson, Graham R; Alroe, Joel; Uhde, Erik; Salthammer, Tunga; Cravigan, Luke; Faghihi, Ehsan Majd; Kumar, Prashant; Morawska, Lidia

    2017-03-01

    While the crushing of concrete gives rise to large quantities of coarse dust, it is not widely recognized that this process also emits significant quantities of ultrafine particles. These particles impact not just the environments within construction activities but those in entire urban areas. The origin of these ultrafine particles is uncertain, as existing theories do not support their production by mechanical processes. We propose a hypothesis for this observation based on the volatilisation of materials at the concrete fracture interface. The results from this study confirm that mechanical methods can produce ultrafine particles (UFP) from concrete, and that the particles are volatile. The ultrafine mode was only observed during concrete fracture, producing particle size distributions with average count median diameters of 27, 39 and 49 nm for the three tested concrete samples. Further volatility measurements found that the particles were highly volatile, showing between 60 and 95% reduction in the volume fraction remaining by 125 °C. An analysis of the volatile fraction remaining found that different volatile material is responsible for the production of particles between the samples.

  16. PREPARATION OF WATERBORNE ULTRAFINE PARTICLES OF EPOXY RESIN BY PHASE INVERSION TECHNIQUE

    Institute of Scientific and Technical Information of China (English)

    YANG Zhengzhong; XU Yuanze; WANG Shengjie; YU Hao; CAI Weizhen

    1997-01-01

    Waterborne ultrafine particles of epoxy resin were prepared by phase inversion technique The results of SEM revealed that the particles diameter was in the range of 50 to l()am and the effects on amount of water required at phase inversion point were also dis()ed.

  17. Partitioning of Black Carbon between ultrafine and fine particle modes in an urban airport vs. urban background environment

    Science.gov (United States)

    Costabile, F.; Angelini, F.; Barnaba, F.; Gobbi, G. P.

    2015-02-01

    In this work, we characterize the Black Carbon (BC) aerosol in an urban airport vs. urban background environment with the objective to evaluate when and how the ultrafine BC dominates the bulk aerosol. Aerosol optical and microphysical properties were measured in a Mediterranean urban area (Rome) at sites impacted by BC sources including fossil fuels (FF), and biomass burning (BB). Experimental BC data were interpreted through measurement-constrained simulations of BC microphysics and optical properties. A "scheme" to separate the ultrafine BC was experimented on the basis of the relation found between changes in the BC partitioning between Aitken and accumulation mode particles, and relevant changes in particle size distribution and optical properties of the bulk aerosol. This separation scheme, applied to experimental data, proved useful to reveal the impact of airport and road traffic emissions. Findings may have important atmospheric implications. The experimented scheme can help separating different BC sources (FF, BB, "aged" BC) when BC size distributions may be very difficult to obtain (satellite, columnar observations, routine monitoring). Indeed, separating the ultrafine BC from the fine BC may provide significant benefits in addressing BC impact on air quality and climate.

  18. Environmental and health impacts of fine and ultrafine metallic particles: Assessment of threat scores

    Energy Technology Data Exchange (ETDEWEB)

    Goix, Sylvaine [Université de Toulouse, INP-ENSAT, Av. Agrobiopôle, 31326 Castanet-Tolosan (France); UMR 5245 CNRS-INP-UPS, EcoLab (Laboratoire d' écologie fonctionnelle), Avenue de l' Agrobiopôle, BP 32607, 31326 Castanet-Tolosan (France); Lévêque, Thibaut [Université de Toulouse, INP-ENSAT, Av. Agrobiopôle, 31326 Castanet-Tolosan (France); UMR 5245 CNRS-INP-UPS, EcoLab (Laboratoire d' écologie fonctionnelle), Avenue de l' Agrobiopôle, BP 32607, 31326 Castanet-Tolosan (France); ADEME (French Agency for Environment and Energy Management), 20 Avenue du Grésillé, BP 90406, 49004 Angers Cedex 01 (France); Xiong, Tian-Tian [Université de Toulouse, INP-ENSAT, Av. Agrobiopôle, 31326 Castanet-Tolosan (France); UMR 5245 CNRS-INP-UPS, EcoLab (Laboratoire d' écologie fonctionnelle), Avenue de l' Agrobiopôle, BP 32607, 31326 Castanet-Tolosan (France); Schreck, Eva [Géosciences Environnement Toulouse (GET), Observatoire Midi Pyrénées, Université de Toulouse, CNRS, IRD, 14 Avenue E. Belin, F-31400 Toulouse (France); and others

    2014-08-15

    This study proposes global threat scores to prioritize the harmfulness of anthropogenic fine and ultrafine metallic particles (FMP) emitted into the atmosphere at the global scale. (Eco)toxicity of physicochemically characterized FMP oxides for metals currently observed in the atmosphere (CdO, CuO, PbO, PbSO{sub 4}, Sb{sub 2}O{sub 3}, and ZnO) was assessed by performing complementary in vitro tests: ecotoxicity, human bioaccessibility, cytotoxicity, and oxidative potential. Using an innovative methodology based on the combination of (eco)toxicity and physicochemical results, the following hazard classification of the particles is proposed: CdCl{sub 2}∼CdO>CuO>PbO>ZnO>PbSO{sub 4}>Sb{sub 2}O{sub 3}. Both cadmium compounds exhibited the highest threat score due to their high cytotoxicity and bioaccessible dose, whatever their solubility and speciation, suggesting that cadmium toxicity is due to its chemical form rather than its physical form. In contrast, the Sb{sub 2}O{sub 3} threat score was the lowest due to particles with low specific area and solubility, with no effects except a slight oxidative stress. As FMP physicochemical properties reveal differences in specific area, crystallization systems, dissolution process, and speciation, various mechanisms may influence their biological impact. Finally, this newly developed and global approach could be widely used in various contexts of pollution by complex metal particles and may improve risk management. - Highlights: • Seven micro- and nano- monometallic characterized particles were studied as references. • Bioaccessibility, eco and cytotoxicity, and oxidative potential assays were performed. • According to calculated threat scores: CdCl{sub 2}∼CdO>CuO>PbO>ZnO>PbSO{sub 4}>Sb{sub 2}O{sub 3}.

  19. Inter-particle interactions and magnetocaloric effect in a sample of ultrafine Fe1-x Hgx particles in Hg

    DEFF Research Database (Denmark)

    Pedersen, Michael Stanley; Mørup, Steen; Linderoth, S.;

    1997-01-01

    Ultrafine magnetic particles consisting of a metastable iron-mercury alloy in Hg have been investigated by Mossbauer spectroscopy and magnetization measurements. It was found that the magnetic particles interact strongly, and around 100 K there is a transition from a superparamagnetic state to a ...

  20. On the spatial distribution and evolution of ultrafine particles in Barcelona

    Directory of Open Access Journals (Sweden)

    M. Dall'Osto

    2013-01-01

    Full Text Available Sources and evolution of ultrafine particles were investigated both horizontally and vertically in the large urban agglomerate of Barcelona, Spain. Within the SAPUSS project (Solving Aerosol Problems by Using Synergistic Strategies, a large number of instruments was deployed simultaneously at different monitoring sites (road, two urban background, regional background, urban tower 150 m a.s.l., urban background tower site 80 m a.s.l. during a 4 week period in September–October 2010. Particle number concentrations (N>5 nm are highly correlated with black carbon (BC at all sites only under strong vehicular traffic influences. By contrast, under cleaner atmospheric conditions (low condensation sink, CS such correlation diverges towards much higher N/BC ratios at all sites, indicating additional sources of particles including secondary production of freshly nucleated particles. Size-resolved aerosol distributions (N10–500 as well as particle number concentrations (N>5 nm allow us to identify three types of nucleation and growth events: (1 a regional type event originating in the whole study region and impacting almost simultaneously the urban city of Barcelona and the surrounding urban background area; (2 a regional type event impacting only the regional background area but not the urban agglomerate; (3 an urban type event which originates only within the city centre but whose growth continues while transported away from the city to the regional background. Furthermore, during these clean air days, higher N are found at tower level than at ground level only in the city centre whereas such a difference is not so pronounced at the remote urban background tower. In other words, this study suggests that the column of air above the city ground level possesses the optimal combination between low CS and high vapour source, hence enhancing the concentrations of freshly nucleated

  1. Scavenging of ultrafine particles by rainfall at a boreal site: observations and model estimations

    Directory of Open Access Journals (Sweden)

    C. Andronache

    2006-05-01

    Full Text Available Values of the scavenging coefficient were determined from observations of ultrafine particles (with diameters in the range 10–510 nm during rain events at a boreal forest site in Southern Finland between 1996 and 2001. The estimated range of values of the scavenging coefficient was [7×10−6–4×10−5] s−1, which is generally higher than model calculations based only on below-cloud processes (Brownian diffusion, interception, and typical charge effects. A new model that includes below-cloud scavenging processes, mixing of ultrafine particles from the boundary layer (BL into cloud, followed by cloud condensation nuclei activation and in-cloud removal by rainfall, is presented. The effective scavenging coefficients estimated from this new model have values comparable with those obtained from observations. Results show that ultrafine particle removal by rain depends on aerosol size, rainfall intensity, mixing processes between BL and cloud elements, in-cloud scavenged fraction, in-cloud collection efficiency, and in-cloud coagulation with cloud droplets. Implications for the treatment of scavenging of BL ultrafine particles in numerical models are discussed.

  2. Exposure to ultrafine particles and respiratory hospitalisations in five European cities

    DEFF Research Database (Denmark)

    Samoli, Evangelia; Andersen, Zorana Jovanovic; Katsouyanni, Klea

    2016-01-01

    Epidemiological evidence on the associations between exposure to ultrafine particles (UFP), with aerodynamic electrical mobility diameters <100 nm, and health is limited. We gathered data on UFP from five European cities within 2001-2011 to investigate associations between short-term changes in c...

  3. PULMONARY AND CARDIAC GENE EXPRESSION FOLLOWING ACUTE ULTRAFINE CARBON PARTICLE INHALATION IN HYPERTENSIVE RATS

    Science.gov (United States)

    Inhalation of ultrafine carbon particles (ufCP) causes cardiac physiological changes without marked pulmonary injury or inflammation. We hypothesized that acute ufCP exposure of 13 months old Spontaneously Hypertensive (SH) rats will cause differential effects on the lung and hea...

  4. Effect of flow characteristics on ultrafine particle emissions from range hoods.

    Science.gov (United States)

    Tseng, Li-Ching; Chen, Chih-Chieh

    2013-08-01

    In order to understand the physical mechanisms of the production of nanometer-sized particulate generated from cooking oils, the ventilation of kitchen hoods was studied by determining the particle concentration, particle size distribution, particle dimensions, and hood's flow characteristics under several cooking scenarios. This research varied the temperature of the frying operation on one cooking operation, with three kinds of commercial cooking oils including soybean oil, olive oil, and sunflower oil. The variations of particle concentration and size distributions with the elevated cooking oil temperatures were presented. The particle concentration increases as a function of temperature. For oil temperatures ranging between 180°C and 210°C, a 5°C increase in temperature increased the number concentration of ultrafine particles by 20-50%. The maximum concentration of ultrafine particles was found to be approximately 6 × 10(6) particles per cm(3) at 260°C. Flow visualization techniques and particle distribution measurement were performed for two types of hood designs, a wall-mounted range hood and an island hood, at a suction flow rate of 15 m(3) min(-1). The flow visualization results showed that different configurations of kitchen hoods induce different aerodynamic characteristics. By comparing the results of flow visualizations and nanoparticle measurements, it was found that the areas with large-scale turbulent vortices are more prone to dispersion of ultrafine particle leakage because of the complex interaction between the shear layers and the suction movement that results from turbulent dispersion. We conclude that the evolution of ultrafine particle concentration fluctuations is strongly affected by the location of the hood, which can alter the aerodynamic features. We suggest that there is a correlation between flow characteristics and amount of contaminant leakage. This provides a comprehensive strategy to evaluate the effectiveness of kitchen hoods

  5. Fabrication of a pure, uniform electroless silver film using ultrafine silver aerosol particles.

    Science.gov (United States)

    Byeon, Jeong Hoon; Kim, Jang-Woo

    2010-07-20

    To obtain evenly distributed pure Ag particles with a narrow size distribution on a polymer membrane, a novel activation procedure with an environmentally friendly, cost-effective method was utilized as a pretreatment before electroless Ag deposition. The pretreatment was first performed on an untreated membrane surface by collecting ultrafine ambient spark-generated Ag aerosol particles. After annealing, the electroless Ag film was fabricated on the collected aerosol particles in the Ag electroless bath. Experimental characterizations showed that the ultrafine Ag particles were uniformly anchored onto the membrane surface through pretreatment, resulting in a pure Ag film of closely packed particles with a narrow size distribution on the membrane, and the properties were comparable to those of an Ag film on wet Sn-Ag-activated membranes.

  6. Preparation and Hydrogen Storage Properties of Mg-Rich Mg-Ni Ultrafine Particles

    Directory of Open Access Journals (Sweden)

    Jianxin Zou

    2012-01-01

    Full Text Available In the present work, Mg-rich Mg-Ni ultrafine powders were prepared through an arc plasma method. The phase components, microstructure, and hydrogen storage properties of the powders were carefully investigated. It is found that Mg2Ni and MgNi2 could be obtained directly from the vapor state reactions between Mg and Ni, depending on the local vapor content in the reaction chamber. A nanostructured MgH2 + Mg2NiH4 hydrogen storage composite could be generated after hydrogenation of the Mg-Ni ultrafine powders. After dehydrogenation, MgH2 and Mg2NiH4 decomposed into nanograined Mg and Mg2Ni, respectively. Thermogravimetry/differential scanning calorimetry (TG/DSC analyses showed that Mg2NiH4 phase may play a catalytic role in the dehydriding process of the hydrogenated Mg ultrafine particles.

  7. Concentration response functions for ultrafine particles and all-cause mortality and hospital admissions: results of a European expert panel elicitation.

    NARCIS (Netherlands)

    Hoek, G.; Boogaard, H.; Knol, A.B.; de Hartog, J.J.; Slottje, P.; Ayres, J.G.; Borm, P.; Brunekreef, B.; Donaldson, K.; Forastiere, F.; Holgate, S.; Kreyling, W.G.; Nemery, B.; Pekkanen, J.; Stone, V.; Wichmann, H.E.; van der Sluijs, J.P.

    2010-01-01

    Toxicological studies have provided evidence of the toxicity of ultrafine particles (UFP), but epidemiological evidence for health effects of ultrafines is limited. No quantitative summary currently exists of concentration-response functions for ultrafine particles that can be used in health impact

  8. On the unification of aircraft ultrafine particle emission data

    Energy Technology Data Exchange (ETDEWEB)

    Kaercher, B.; Busen, R. [DLR Deutsches Zentrum fuer Luft- und Raumfahrt e.V., Wessling (Germany). Inst. fuer Physik der Atmosphaere; Turco, R.P.; Yu Fangqun [California Univ., Los Angeles, CA (United States). Dept. of Atmospheric Sciences; Danilin, M.Y.; Weisenstein, D.K. [Atmospheric and Environmental Research, Inc., Cambridge, MA (United States); Miake-Lye, R.C. [Aerodyne Research, Inc., Billerica, MA (United States)

    2000-03-01

    To predict the environmental impacts of future commercial aviation, intensive studies have been launched to measure the properties and effects of aircraft emissions. These observations have revealed an extremely wide variance with respect to the number and sizes of the particles produced in the exhaust plumes. Aircraft aerosol ultimately contributes to the population of cloud-forming nuclei, and may lead to significant global radiative and chemical perturbations. In this paper, recent discoveries are coordinated and unified in the form of a physically consistent plume aerosol model that explains most of the observational variance. Using this new approach, it is now practical to carry out reliable global atmospheric simulations of aircraft effects, as demonstrated by a novel assessment of the perturbation of the stratospheric aerosol layer by a supersonic aircraft fleet. (orig.)

  9. Experiments and Modeling of the Preparation of Ultrafine Calcium Carbonate in Spouted Beds with Inert Particles

    Institute of Scientific and Technical Information of China (English)

    林诚; 朱涛; 朱跃姿; 张济宇

    2003-01-01

    A novel reaction-drying process was carried out in a spouted bed reactor with inert particles and used to prepare ultrafine CaCO3 particles. Effects of concentrations of CO2 and Ca(OH)2, and reaction temperature on Ca(OH)2 conversion were experimentally investigated. The particle sizes and composition of CaCO3 produced were characterized with transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results indicated that ultrafine CaCO3 particles with mean size of 80 nm could be obtained with this novel process.By modifying the Arrhenius Equation and considering the Ca(OH)2 state, a kinetic model was established to describe the process in the spouted bed. The model parameters estimated from the reaction-drying experiments were found to fit well the experimental data, indicating the applicability of the proposed kinetic model.

  10. Mode resolved density of atmospheric aerosol particles

    Directory of Open Access Journals (Sweden)

    P. Aalto

    2008-09-01

    Full Text Available In this study, we investigate the mode resolved density of ultrafine atmospheric particles measured in boreal forest environment. The method used here enables us to find the distinct density information for each mode in atmospheric fine particle population: the density values for nucleation, Aitken, and accumulation mode particles are presented. The experimental data was gained during 2 May 2005–19 May 2005 at the boreal forest measurement station "SMEAR II" in Hyytiälä, Southern Finland. The density values for accumulation mode varied from 1.1 to 2 g/cm3 (average 1.5 g/cm3 and for Aitken mode from 0.4 to 2 g/cm3 (average 0.97 g/cm3. As an overall trend during the two weeks campaign, the density value of Aitken mode was seen to gradually increase. With the present method, the time dependent behaviour of the particle density can be investigated in the time scale of 10 min. This allows us to follow the density evolution of the nucleation mode particles during the particle growth process following the nucleation burst. The density of nucleation mode particles decreased during the growth process. The density values for 15 nm particles were 1.2–1.5 g/cm3 and for grown 30 nm particles 0.5–1 g/cm3. These values are consistent with the present knowledge that the condensing species are semi-volatile organics, emitted from the boreal forest.

  11. Determinants of personal exposure to PM2.5, ultrafine particle counts, and CO in a transport microenvironment.

    Science.gov (United States)

    Kaur, S; Nieuwenhuijsen, M J

    2009-07-01

    Short-term human exposure concentrations to PM2.5, ultrafine particle counts (particle range: 0.02-1 microm), and carbon monoxide (CO) were investigated at and around a street canyon intersection in Central London, UK. During a four week field campaign, groups of four volunteers collected samples at three timings (morning, lunch, and afternoon), along two different routes (a heavily trafficked route and a backstreet route) via five modes of transport (walking, cycling, bus, car, and taxi). This was followed by an investigation into the determinants of exposure using a regression technique which incorporated the site-specific traffic counts, meteorological variables (wind speed and temperature) and the mode of transport used. The analyses explained 9, 62, and 43% of the variability observed in the exposure concentrations to PM2.5, ultrafine particle counts, and CO in this study, respectively. The mode of transport was a statistically significant determinant of personal exposure to PM2.5, ultrafine particle counts, and CO, and for PM2.5 and ultrafine particle counts it was the most important determinant. Traffic count explained little of the variability in the PM2.5 concentrations, but it had a greater influence on ultrafine particle count and CO concentrations. The analyses showed that temperature had a statistically significant impact on ultrafine particle count and CO concentrations. Wind speed also had a statistically significant effect but smaller. The small proportion in variability explained in PM2.5 by the model compared to the largest proportion in ultrafine particle counts and CO may be due to the effect of long-range transboundary sources, whereas for ultrafine particle counts and CO, local traffic is the main source.

  12. Distribution pattern of inhaled ultrafine gold particles in the rat lung.

    Science.gov (United States)

    Takenaka, S; Karg, E; Kreyling, W G; Lentner, B; Möller, W; Behnke-Semmler, M; Jennen, L; Walch, A; Michalke, B; Schramel, P; Heyder, J; Schulz, H

    2006-09-01

    The role of alveolar macrophages in the fate of ultrafine particles in the lung was investigated. Male Wistar-Kyoto rats were exposed to ultrafine gold particles, generated by a spark generator, for 6 h at a concentration of 88 microg/m3 (4 x 10(6)/cm3, 16 nm modal mobility diameter). Up to 7 days, the animals were serially sacrificed, and lavaged cells and lung tissues were examined by transmission electron microscopy. The gold concentration/content in the lung, lavage fluid, and blood was estimated by inductively coupled plasma-mass spectrometry. Gold particles used were spherical and electron dense with diameters of 5-8 nm. The particles were individual or slightly agglomerated. By inductively coupled plasma-mass spectrometry analysis of the lung, 1945 +/- 57 ng (mean +/- SD) and 1512 +/- 184 ng of gold were detected on day 0 and on day 7, respectively, indicating that a large portion of the deposited gold particles was retained in the lung tissue. In the lavage fluid, 573 +/- 67 ng and 96 +/- 29 ng were found on day 0 and day 7, respectively, which means that 29% and 6% of the retained gold particles were lavageable on these days. A low but significant increase of gold (0.03 to 0.06% of lung concentration) was found in the blood. Small vesicles containing gold particles were found in the cytoplasm of alveolar macrophages. In the alveolar septum, the gold particles were enclosed in vesicles observed in the cytoplasm of alveolar type I epithelial cells. These results indicate that inhaled ultrafine gold particles in alveolar macrophages and type I epithelial cells are processed by endocytotic pathways, though the uptake of the gold particles by alveolar macrophages is limited. To a low degree, systemic particle translocation took place.

  13. Numerical Model for Ultra-fine Particles in the Absence and Presence of Gravity

    Science.gov (United States)

    Dutt, Meenakshi; Elliott, James A.

    2009-06-01

    Length scales of particles and their surrounding medium strongly determines the nature of their interactions with one another and their responses to external fields. We are interested in systems of ultra-fine particles (0.1-1.0 micron) such as volcanic ash, soot from forest fires, solid aerosols, or fine powders for pharmaceutical inhalation applications. We have a developed a numerical model which captures the dominant physical interactions which control the behavior of these systems. The adhesive interactions between the particles use the Derjaguin-Muller-Toporov (DMT) adhesion theory along with the van der Waals attraction. The elastic restoring forces are modeled by the Hertz's contact model, and require details of material properties such as the Young's modulus and Poisson ratio. Commencing with a three dimensional gas of ultra-fine particles, the absence of gravity does not produce any noticeable clustering. The presence of gravity initially generates a large population of clusters with small number of particles, as the particles settle. The initial population of small clusters or single particles which have settled decrease with time as more particles, or clusters, agglomerate with one another. Our final results show clusters containing 10 to 100 particles, with a larger population of small clusters. We present details of the model, and some preliminary results which demonstrate the influence of the particle surface properties on the clustering dynamics of these systems, in the absence and presence of gravity (M. Dutt, J. A. Elliott, et al. in press).

  14. Impact of two particle measurement techniques on the determination of N95 class respirator filtration performance against ultrafine particles

    Energy Technology Data Exchange (ETDEWEB)

    Mostofi, Reza [Department of Building, Civil and Environmental Engineering Concordia University, Montreal, Quebec (Canada); Noeel, Alexandra [Department of Environmental and Occupational Health, University of Montreal, Montreal, Quebec (Canada); Haghighat, Fariborz, E-mail: haghi@bcee.concordia.ca [Department of Building, Civil and Environmental Engineering Concordia University, Montreal, Quebec (Canada); Bahloul, Ali [Institut de Recherche Robert-Sauve en Sante et en Securite du Travail, Montreal, Quebec H3A 3C2 (Canada); Lara, Jaime [Department of Environmental and Occupational Health, University of Montreal, Montreal, Quebec (Canada); Cloutier, Yves [Institut de Recherche Robert-Sauve en Sante et en Securite du Travail, Montreal, Quebec H3A 3C2 (Canada)

    2012-05-30

    Highlights: Black-Right-Pointing-Pointer Performance evaluation of respirator using two different measurement techniques. Black-Right-Pointing-Pointer Impaction and electrical mobility were used to characterize ultrafine particle. Black-Right-Pointing-Pointer The experiment was done using ultrafine-sized poly-dispersed aerosols. Black-Right-Pointing-Pointer Both techniques show that MPPS would occur at a similar size range. - Abstract: The purpose of this experimental study was to compare two different particle measurement devices; an Electrical Low Pressure Impactor (ELPI) and a Scanning Mobility Particle Sizer (SMPS), to measure the number concentration and the size distribution of NaCl salt aerosols to determine the collection efficiency of filtering respirators against poly disperse aerosols. Tests were performed on NIOSH approved N95 filtering face-piece respirators (FFR), sealed on a manikin head. Ultrafine particles found in the aerosols were also collected and observed by transmission electron microscopy (TEM). According to the results, there is a systematic difference for the particle size distribution measured by the SMPS and the ELPI. It is largely attributed to the difference in the measurement techniques. However, in spite of these discrepancies, reasonably similar trends were found for the number concentration with both measuring instruments. The particle penetration, calculated based on mobility and aerodynamic diameters, never exceeded 5% for any size range measured at constant flow rate of 85 L/min. Also, the most penetrating particle size (MPPS), with the lowest filtration efficiency, would occur at a similar ultrafine size range <100 nm. With the ELPI, the MPPS was at 70 nm aerodynamic diameter, whereas it occurred at 40 nm mobility diameter with the SMPS.

  15. Abrasion of ultrafine WC-Co by fine abrasive particles

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Abrasive wear of a series of WC-(5%-14%, mass fiaction)Co hardmetals was investigated employing coarse and fine SiC abrasive under two-body dry abrasion conditions with pin-on-disc and edge-on-disc test arrangements. Unexpectedly, it is found that submicron grades demonstrate substantially higher wear rates comparing with the coarse grades if fine abrasive is utilized in pin-on-disc tests. Such a behavior is attributed to changes in a ratio of abrasive size to size of hard phase as finer abrasive is used.The edge-on-disc test demonstrates that edge wear may be described in two stages with the highest wear rates at the beginning stage.This behavior is associated with a transition of wear mechanisms as edge is wider due to wear. Compared with the ultrafine grades of the same Co content, the coarse grades demonstrate higher wear rates at the beginning, but lower wear rates at the final stage. Wear rates and mechanisms observed at final stage correlate well to the results observed for pin-on-disc tests employing fine abrasive.

  16. DYNAMIC RHEOLOGICAL BEHAVIOR OF POLYPROPYLENE FILLED WITH ULTRA-FINE POWDERED RUBBER PARTICLES

    Institute of Scientific and Technical Information of China (English)

    Qiang Zheng; Yan-xia Cao; Miao Du

    2004-01-01

    Dynamic rheological characteristics of polypropylene (PP) filled with ultra-fine full-vulcanized powdered rubber (UFPR) composed of styrene-butadiene copolymer were studied through dynamic rheological measurements on an Advanced Rheometric Expansion System (ARES). A specific viscoelastic phenomenon, i.e. "the second plateau", appeared at low frequencies, and exhibits a certain dependence on the amount of rubber particles and the dispersion state in the matrix. This phenomenon is attributed to the formation of aggregation structure of rubber particles. The analyses of Cole-Cole diagrams of the dynamic viscoelastic functions suggest that the heterogeneity of the composites is enhanced on increasing both particle content and temperature.

  17. Ultrafine carbon particles down-regulate CYP1B1 expression in human monocytes

    Directory of Open Access Journals (Sweden)

    Ziegler-Heitbrock Loems

    2009-10-01

    Full Text Available Abstract Background Cytochrome P450 monoxygenases play an important role in the defence against inhaled toxic compounds and in metabolizing a wide range of xenobiotics and environmental contaminants. In ambient aerosol the ultrafine particle fraction which penetrates deeply into the lungs is considered to be a major factor for adverse health effects. The cells mainly affected by inhaled particles are lung epithelial cells and cells of the monocyte/macrophage lineage. Results In this study we have analyzed the effect of a mixture of fine TiO2 and ultrafine carbon black Printex 90 particles (P90 on the expression of cytochrome P450 1B1 (CYP1B1 in human monocytes, macrophages, bronchial epithelial cells and epithelial cell lines. CYP1B1 expression is strongly down-regulated by P90 in monocytes with a maximum after P90 treatment for 3 h while fine and ultrafine TiO2 had no effect. CYP1B1 was down-regulated up to 130-fold and in addition CYP1A1 mRNA was decreased 13-fold. In vitro generated monocyte-derived macrophages (MDM, epithelial cell lines, and primary bronchial epithelial cells also showed reduced CYP1B1 mRNA levels. Benzo[a]pyrene (BaP is inducing CYB1B1 but ultrafine P90 can still down-regulate gene expression at 0.1 μM of BaP. The P90-induced reduction of CYP1B1 was also demonstrated at the protein level using Western blot analysis. Conclusion These data suggest that the P90-induced reduction of CYP gene expression may interfere with the activation and/or detoxification capabilities of inhaled toxic compounds.

  18. REAL TIME MEASUREMENT OF ULTRAFINE AND NANO PARTICLES AND SIGNIFICANCE OF OPERATING GEARS

    Directory of Open Access Journals (Sweden)

    H. A. NAKHAWA

    2017-03-01

    Full Text Available This research paper focuses on characterization of ultrafine and nanoparticle emissions from diesel vehicle to investigate their physical characterization in terms of number and size as they are more vulnerable and responsible for toxicity, mutagenicity and carcinogenicity. An investigation has been carried out to identify the significance of different operating gears, clutch, declutch and gear change operations for their contributions to particle number(PN on urban and extra urban part of the driving cycle. A bi-modal particle size distribution pattern was observed for both urban and extra urban parts where almost all the particles are below 200 nm and particle number peaks appear at 7 to 8 nm and at 70 nm. Nano particles contribute approximately, 70% of total particle number over urban part. Experimental investigation shows that the most significant gear for their contribution to particle number are 3rd and 5th gears on urban and extra urban part of the driving cycle respectively.

  19. Characteristics of ultrafine particles emitted from adimethyl ether (DME) engine

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Measurements of exhaust particle number concentration and size distribution from a dimethyl ether (DME) engine at different engine loads and speeds were carried out by using a two-stage dilution system and an SMPS. The results of the DME engine were compared with those of the original diesel engine. The fuel composition had significant effects on the exhaust particle size distribution, the total exhaust particle number and mass concentrations. Compared with those of the DME engine, the particle mass emissions of the diesel engine increased 5.7-17.7 times. At high engine speed (n=2200 r/min),compared with those of the DME engine, the total particle number emissions of the diesel engine increased 0.75-2.2 times, while the total particle number emissions of the diesel engine decreased by about 50%-80% for middle and high loads at middle engine speed (n=1400 r/min). Compared with those of the DME engine, the total exhaust particle number concentrations in the accumulation mode of the diesel engine increased 4.2-62.6 times and the exhaust particle geometric number mean diameters in the accumulation mode increased by about 10-30 nm. This correlated with higher oxygen level and lack of C-C bonds in DME. A lot of nucleation mode particles were emitted from the DME engine, this correlated with the processes of nucleation and condensation of the volatile and semi-volatile compounds in the exhaust gas.

  20. Characterization of ultrafine particle number concentration and new particle formation in urban environment of Taipei, Taiwan

    Science.gov (United States)

    Cheung, H. C.; Chou, C. C.-K.; Huang, W.-R.; Tsai, C.-Y.

    2013-04-01

    An intensive aerosol characterization experiment was performed at the Taipei Aerosol and Radiation Observatory (TARO, 25.02° N, 121.53° E) in the urban area of Taipei, Taiwan during July 2012. Number concentration and size distribution of aerosol particles were measured continuously, which were accompanied by concurrent measurements of mass concentration of submicron particles, PM (d ≤ 1 μm), and photolysis rate of ozone, J(O1D). The averaged number concentrations of total (Ntotal), accumulation mode (Nacu), Aitken mode (Ntotal), and nucleation mode (Nnuc) particles were 7.6 × 103 cm-3, 1.2 × 103 cm-3, 4.4 × 103 cm-3, and 1.9 × 103 cm-3, respectively. Accordingly, the ultrafine particles (UFPs, d ≤ 100 nm) accounted for 83% of the total number concentration of particles measured in this study (10 ≤ d ≤ 429 nm), indicating the importance of UFPs to the air quality and radiation budget in Taipei and its surrounding areas. An averaged Nnuc/NOx ratio of ~60 cm-3 ppbv-1 was derived from nighttime measurements, which was suggested to be the characteristic of vehicle emissions that contributed to the "urban background" of nucleation mode particles throughout a day. On the contrary, it was found that the number concentration of nucleation mode particles was independent of NOx and could be elevated up to 10 times the "urban background" levels during daytime, suggesting a substantial amount of nucleation mode particles produced from photochemical processes. Consistency in the time series of the nucleation mode particle concentration and the proxy of H2SO4 production, UVB·SO2, for new particle formation (NPF) events showed that photo-oxidation of SO2 was responsible for the formation of new particles in our study area. Moreover, analysis upon the diameter growth rate, GR, and formation rate of nucleation mode particles, J10-25, found that the values of GR (8.5 ± 6.8 nm h-1) in Taipei were comparable to other urban areas, whereas the values of J10-25 (2.2 ± 1

  1. [Experimental study on the size spectra and emission factor of ultrafine particle from coal combustion].

    Science.gov (United States)

    Sun, Zai; Yang, Wen-jun; Xie, Xiao-fang; Chen, Qiu-fang; Cai, Zhi-liang

    2014-12-01

    The emission characteristics of ultrafine particles released from pulverized coal combustion were studied, the size spectra of ultrafine particles (5.6-560 nm) were measured with FMPS (fast mobility particle sizer) on a self-built aerosol experiment platform. Meanwhile, a particle dynamic evolution model was established to obtain the particle deposition rate and the emission rate through the optimized algorithm. Finally, the emission factor was calculated. The results showed that at the beginning of particle generation, the size spectra were polydisperse and complex, the initial size spectra was mainly composed of three modes including 10 nm, 30-40 nm and 100-200 nm. Among them, the number concentration of mode around 10 nm was higher than those of other modes, the size spectrum of around 100-200 nm was lognormal distributed, with a CMD (count median diameter) of around 16 nm. Then, as time went on, the total number concentration was decayed by exponential law, the CMD first increased and then tended to be stable gradually. The calculation results showed that the emission factor of particles from coal combustion under laboratory condition was (5.54 x 10(12) ± 2.18 x 10(12)) unit x g(-1).

  2. Seasonality of ultrafine and sub-micron aerosols and the inferences on particle formation processes

    Science.gov (United States)

    Cheung, H. C.; Chou, C. C.-K.; Chen, M.-J.; Huang, W.-R.; Huang, S.-H.; Tsai, C.-Y.; Lee, C. S.-L.

    2015-08-01

    The aim of this study is to investigate the seasonal variations in the physicochemical properties of atmospheric ultrafine particles (UFPs, d ≤ 100nm) and submicron particles (PM1, d ≤ 1 μm) in an East-Asian urban area, which are hypothesized to be affected by the interchange of summer and winter monsoons. An observation experiment was conducted at the TARO, an urban aerosol station in Taipei, Taiwan, from October 2012 to August 2013. The measurements included the mass concentration and chemical composition of UFPs and PM1, as well as the particle number concentration (PNC) and size distribution (PSD) with size range of 4-736 nm. The results indicate that the mass concentration of PM1 was elevated during cold seasons with peak level of 18.5 μg m-3 in spring, whereas the highest UFPs concentration was measured in summertime with a seasonal mean of 1.62 μg m-3. Moreover, chemical analysis revealed that the UFPs and PM1 were characterized by distinct composition; UFPs were composed mostly of organics, whereas ammonium and sulfate were the major constituents in PM1. The seasonal median of total PNCs ranged from 13.9 × 103 cm-3 in autumn to 19.4 × 103 cm-3 in spring. The PSD information retrieved from the corresponding PNC measurements indicates that the nucleation mode PNC (N4-25) peaked at 11.6 × 103 cm-3 in winter, whereas the Aitken mode (N25-100) and accumulation mode (N100-736) exhibited summer maxima at 6.0 × 103 and 3.1 × 103 cm-3, respectively. The shift in PSD during summertime is attributed to the enhancement in the photochemical production of condensable organic matter that, in turn, contributes to the growth of aerosol particles in the atmosphere. In addition, remarkable photochemical production of particles was observed in spring and summer seasons, which was characterized with averaged particle growth and formation rates of 4.3 ± 0.8 nm h-1 and 1.6 ± 0.8 cm-3 s-1, respectively. The prevalence of new particle formation (NPF) in summer is

  3. Regional impacts of ultrafine particle emissions from the surface of the Great Lakes

    Directory of Open Access Journals (Sweden)

    S. H. Chung

    2011-12-01

    Full Text Available Quantifying the impacts of aerosols on climate requires a detailed knowledge of both the anthropogenic and the natural contributions to the aerosol population. Recent work has suggested a previously unrecognized natural source of ultrafine particles resulting from breaking waves at the surface of large freshwater lakes. This work is the first modeling study to investigate the potential for this newly discovered source to affect the aerosol number concentrations on regional scales. Using the WRF-Chem modeling framework, the impacts of wind-driven aerosol production from the surface of the Great Lakes were studied for a July 2004 test case. Simulations were performed for a base case with no lake surface emissions, a case with lake surface emissions included, and a default case wherein large freshwater lakes emit marine particles as if they were oceans. Results indicate that the lake surface emissions can enhance the surface-level aerosol number concentration by ~20% over the remote northern Great Lakes and by ~5% over other parts of the Great Lakes. These results were highly sensitive to the new particle formation (i.e., nucleation parameterization within WRF-Chem; when the new particle formation process was deactivated, surface-layer enhancements from the lake emissions increased to as much as 200%. The results reported here have significant uncertainties associated with the lake emission parameterization and the way ultrafine particles are modeled within WRF-Chem. Nevertheless, the magnitudes of the impacts found in this study suggest that further study to quantify the emissions of ultrafine particles from the surface of the Great Lakes is merited.

  4. Investigation on the potential generation of ultrafine particles from the tire-road interface

    Science.gov (United States)

    Mathissen, Marcel; Scheer, Volker; Vogt, Rainer; Benter, Thorsten

    2011-11-01

    There has been some discussion in the literature on the generation of ultrafine particles from tire abrasion of studded and non-studded tires tested in the laboratory environment. In the present study, the potential generation of ultrafine particles from the tire road interface was investigated during real driving. An instrumented Sport Utility Vehicle equipped with summer tires was used to measure particle concentrations with high temporal resolution inside the wheel housing while driving on a regular asphalt road. Different driving conditions, i.e., straight driving, acceleration, braking, and cornering were applied. For normal driving conditions no enhanced particle number concentration in the size range 6-562 nm was found. Unusual maneuvers associated with significant tire slip resulted in measurable particle concentrations. The maximum of the size distribution was between 30 and 60 nm. An exponential increase of the particle concentration with velocity was measured directly at the disc brakes for full stop brakings. A tracer gas experiment was carried out to estimate the upper limit of the emission factor during normal straight driving.

  5. Treatment of losses of ultrafine aerosol particles in long sampling tubes during ambient measurements

    Science.gov (United States)

    Kumar, Prashant; Fennell, Paul; Symonds, Jonathan; Britter, Rex

    Long sampling tubes are often required for particle measurements in street canyons. This may lead to significant losses of the number of ultrafine (those below 100 nm) particles within the sampling tubes. Inappropriate treatment of these losses may significantly change the measured particle number distributions (PND), because most of the ambient particles, by number, exist in the ultrafine size range. Based on the Reynolds number (Re) in the sampling tubes, most studies treat the particle losses using the Gormley and Kennedy laminar flow model (Gormley, P.G., Kennedy, M., 1949. Diffusion from a stream following through a cylinderical tube. Proceedings of Royal Irish Academy 52, 163-169.) or the Wells and Chamberlain turbulent flow model (Wells, A.C., Chamberlain, A.C., 1967. Transport of small particles to vertical surfaces. British Journal of Applied Physics 18, 1793-1799.). Our experiments used a particle spectrometer with various lengths (1.00, 5.47, 5.55, 8.90 and 13.40 m) of sampling tube to measure the PNDs in the 5-2738 nm range. Experiments were performed under different operating conditions to measure the particle losses through silicone rubber tubes of circular cross-section (7.85 mm internal diameter). Sources of particles included emissions from an idling diesel engine car in a street canyon, emissions from a burning candle and those from the generation of salt aerosols using a nebuliser in the laboratory. Results showed that losses for particles below ≈20 nm were important and were largest for the smallest size range (5-10 nm), but were modest for particles above ≈20 nm. In our experiments the laminar flow model did not reflect the observations for small Re. This may be due to the sampling tubes not being kept straight or other complications. In situ calibration or comparison appears to be required.

  6. Ultrafine Particles in Residential Indoors and Doses Deposited in the Human Respiratory System

    Directory of Open Access Journals (Sweden)

    Maurizio Manigrasso

    2015-09-01

    Full Text Available Indoor aerosol sources may significantly contribute to the daily dose of particles deposited into the human respiratory system. Therefore, it is important to characterize the aerosols deriving from the operations currently performed in an indoor environment and also to estimate the relevant particle respiratory doses. For this aim, aerosols from indoor combustive and non-combustive sources were characterized in terms of aerosol size distributions, and the relevant deposition doses were estimated as a function of time, particle diameter and deposition site in the respiratory system. Ultrafine particles almost entirely made up the doses estimated. The maximum contribution was due to particles deposited in the alveolar region between the 18th and the 21st airway generation. When cooking operations were performed, respiratory doses per unit time were about ten-fold higher than the relevant indoor background dose. Such doses were even higher than those associated with outdoor traffic aerosol.

  7. Chemical preparation and investigation of Fe-P-B ultrafine amorphous alloy particles

    Institute of Scientific and Technical Information of China (English)

    胡征; 吴勇; 范以宁; 颜其洁; 陈懿

    1997-01-01

    A series of Fe-P-B ultrafine amorphous alloy particles has been prepared by the chemical reduction method The composition and size of the particles have been effectively adjusted.Mossbauer spectroscopy in addition to sonic other techniques has been used to investigate the reaction process,the factors that influence the preparation,the crystallization of the particles,and the interactions between the components within them.The results indicate that the co-deposition of iron,phosphorus and boron atoms in the solution at room temperature forms Fe-P-B amorphous alloy particles,and a preferential bonding of Fe-P bond to Fe-B one exists in the particles.

  8. The Behavior of Ultrafine Particles in the Absence and Presence of External Fields

    Science.gov (United States)

    Dutt, Meenakshi; Hancock, Bruno; Bentham, Craig; Elliott, James

    2007-03-01

    Length scales of particles and their surrounding medium strongly determines the nature of their interactions with one another and their responses to external fields. We are interested in systems of ultrafine particles (0.1 - 1.0 micron) such as volcanic ash, solid aerosols, or fine powders for pharmaceutical ihalation applications. We develop a numerical model for these systems using the Derjaguin-Muller-Toporov (DMT) adhesion theory along with the van der Waals attraction between the particles and their contact mechanical interactions. We study the dynamics of these systems in the absence and presence of gravity by controlling the particle size, and thereby, the surface properties of the particles. Finally, we explore the response of these systems to external fields by studying the evolution of the internal microstructure under contant load and shear strain.

  9. Ultrafine-grained mineralogy and matrix chemistry of olivine-rich chondritic interplanetary dust particles

    Science.gov (United States)

    Rietmeijer, F. J. M.

    1989-01-01

    Olivine-rich chondritic interplanetary dust particles (IDPs) are an important subset of fluffy chondritic IDPs collected in the earth's stratosphere. Particles in this subset are characterized by a matrix of nonporous, ultrafine-grained granular units. Euhedral single crystals, crystals fragments, and platey single crystals occur dispersed in the matrix. Analytical electron microscopy of granular units reveals predominant magnesium-rich olivines and FeNi-sulfides embedded in amorphous carbonaceous matrix material. The variable ratio of ultrafine-grained minerals vs. carbonaceous matrix material in granular units support variable C/Si ratios, and some fraction of sulfur is associated with carbonaceous matrix material. The high Mg/(Mg+Fe) ratios in granular units is similar to this distribution in P/Comet Halley dust. The chondritic composition of fine-grained, polycrystalline IDPs gradually breaks down into nonchondritic, and ultimately, single mineral compositions as a function of decreased particle mass. The relationship between particle mass and composition in the matrix of olivine-rich chondritic IDPs is comparable with the relationship inferred for P/Comet Halley dust.

  10. Ultrafine particles emitted by flame and electric arc guns for thermal spraying of metals.

    Science.gov (United States)

    Bémer, Denis; Régnier, Roland; Subra, Isabelle; Sutter, Benjamin; Lecler, Marie T; Morele, Yves

    2010-08-01

    The ultrafine aerosol emitted by thermal spraying of metals using flame and electric arc processes has been characterized in terms of particle size distribution and emission rates based on both particle number and mass. Thermal spraying of Zn, Zn/Al, and Al was studied. Measurements taken using an electrical low pressure impactor and a condensation nucleus counter reveal an aerosol made up of very fine particles (80-95% of number distribution electric arc process are very high, the largest values being recorded during spraying of pure aluminium. This process generates high particle emissions and therefore requires careful consideration and possible rethinking of currently implemented protection measures: ventilated cabins, dust collectors, and personal protective equipment.

  11. Exposure to ultrafine particles in relation to indoor events and dwelling characteristics

    DEFF Research Database (Denmark)

    Spilak, Michal; Frederiksen, Marie; Kolarik, Barbara

    2014-01-01

    Exposure to ultrafine particles (UFP) in homes is associated with health risks such as cardiovascular disease and/or respiratory problems. These risks are heightened by the long time that people spend indoors. Therefore reducing the particle concentration in homes leads to improved health among i....... Furthermore, the winter season was associated significantly with high UFP levels indoors. Results of our study also indicated that owning a pet, wood-type floors and floor levels close to the ground are associated with increased UFP levels....... occupants. The use of particle filtration units may be an effective way of reducing UFP indoors. The purpose of this study was to evaluate associations between UFP concentrations and dwelling characteristics, estimate UFP removal rates indoors and to assess the effectiveness of installed particle filtration...

  12. Separation of Fischer-Tropsch Wax Products from Ultrafine Iron Catalyst Particles

    Energy Technology Data Exchange (ETDEWEB)

    Amitava Sarkar; James K. Neathery; Burtron H. Davis

    2006-12-31

    A fundamental filtration study was started to investigate the separation of Fischer-Tropsch Synthesis (FTS) liquids from iron-based catalyst particles. Slurry-phase FTS in slurry bubble column reactor systems is the preferred mode of operation since the reaction is highly exothermic. Consequently, heavy wax products in one approach may be separated from catalyst particles before being removed from the reactor system. Achieving an efficient wax product separation from iron-based catalysts is one of the most challenging technical problems associated with slurry-phase iron-based FTS and is a key factor for optimizing operating costs. The separation problem is further compounded by attrition of iron catalyst particles and the formation of ultra-fine particles.

  13. Ultrafine particle removal by residential heating, ventilating, and air-conditioning filters.

    Science.gov (United States)

    Stephens, B; Siegel, J A

    2013-12-01

    This work uses an in situ filter test method to measure the size-resolved removal efficiency of indoor-generated ultrafine particles (approximately 7-100 nm) for six new commercially available filters installed in a recirculating heating, ventilating, and air-conditioning (HVAC) system in an unoccupied test house. The fibrous HVAC filters were previously rated by the manufacturers according to ASHRAE Standard 52.2 and ranged from shallow (2.5 cm) fiberglass panel filters (MERV 4) to deep-bed (12.7 cm) electrostatically charged synthetic media filters (MERV 16). Measured removal efficiency ranged from 0 to 10% for most ultrafine particles (UFP) sizes with the lowest rated filters (MERV 4 and 6) to 60-80% for most UFP sizes with the highest rated filter (MERV 16). The deeper bed filters generally achieved higher removal efficiencies than the panel filters, while maintaining a low pressure drop and higher airflow rate in the operating HVAC system. Assuming constant efficiency, a modeling effort using these measured values for new filters and other inputs from real buildings shows that MERV 13-16 filters could reduce the indoor proportion of outdoor UFPs (in the absence of indoor sources) by as much as a factor of 2-3 in a typical single-family residence relative to the lowest efficiency filters, depending in part on particle size.

  14. Regional impacts of ultrafine particle emissions from the surface of the Great Lakes

    Directory of Open Access Journals (Sweden)

    S. H. Chung

    2011-05-01

    Full Text Available Quantifying the impacts of aerosols on climate requires a detailed knowledge of both the anthropogenic and the natural contributions to the aerosol population. Recent work has suggested a previously unrecognized natural source of ultrafine particles resulting from breaking waves at the surface of large freshwater lakes. This work is the first modeling study to investigate the potential for this newly discovered source to affect the aerosol number concentrations on regional scales. Using the WRF-Chem modeling framework, the impacts of wind-driven aerosol production from the surface of the Great Lakes were studied for a July 2004 test case. Simulations were performed for a base case with no lake surface emissions, a case with lake surface emissions included, and a default case wherein large freshwater lakes emit marine particles as if they were oceans. Results indicate that the lake surface emissions can enhance the surface level aerosol number concentration by ∼20 % over the remote northern Great Lakes and by ∼5 % over other parts of the Great Lakes. These results were highly sensitive the nucleation parameterization within WRF-Chem; when the nucleation process was deactivated, surface-layer enhancements from the lake emissions increased to as much as 200 %. The results reported here have significant uncertainties associated with the lake emission parameterization and the way ultrafine particles are modeled within WRF-Chem. Nevertheless, the magnitude of the impacts found in this study suggest that further study of this phenomena is merited.

  15. Fine and Ultrafine Particles from Combustion Sources - Investigations with in-situ techniques

    Energy Technology Data Exchange (ETDEWEB)

    Pagels, Joakim

    2005-04-01

    Fine airborne particles are associated with adverse health effects in the human population. The aim of this research was to develop and evaluate methods for in-situ characterisation of fine and ultrafine particles and to determine their deposition in the human airways. The aim was also to increase knowledge about health and environmentally relevant properties of aerosols from biomass combustion and selected indoor sources. The methods include instrumental techniques such as Scanning Mobility Particle Sizer (SMPS), Electrical Low-Pressure Impactor (ELPI), Aerodynamic Particle Sizer (APS) and Tandem Differential Mobility Analysers (TDMA) based on volatility and hygroscopic growth. Filter samplers and impactors were used for collecting particles on substrates for subsequent chemical analysis. Emissions from local district heating plants (0.5-12 MW), based on moving grate combustion of woody fuels, were sampled with a dilution system and characterised. Particles from the indoor sources of cigarettes, incense and candles were examined in the laboratory by using an airtight 22 m{sup 3} stainless steel chamber. A set-up to determine respiratory deposition in humans was constructed. It was automatised and uses an electrical mobility spectrometer with an improved inversion algorithm to perform fast measurements of particles of different sizes in the inhaled and exhaled air. It was evaluated on human test-persons. The investigated biomass combustion sources emit high concentrations of fine and ultrafine particles. The chemical composition is dominated by KCl and K{sub 2}SO{sub 4}; Zn, Cd and Pb were also quantified. Elemental carbon was identified in particles larger than 150 nm during periods of incomplete combustion. The particle concentration depends on the fuel ash content and the combustion efficiency. The aerosol is essentially internally mixed with hygroscopic growth factors significantly higher than reported for diesel exhaust and environmental tobacco smoke. The

  16. Formation of Ultrafine Metal Particles and Metal Oxide Precursor on Anodized Al by Electrolysis Deposition

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Nickel was deposited by ac electrolysis deposition in the pores of the porous oxide film of Al produced by anodizing in phosphoric acid. Ultrafine rod-shaped Ni particles were formed in the pores. At the same time a film of Ni oxide precursor was developed on the surface of the porous oxide film. The Ni particles and the Ni oxide precursor were examined by SEM, TEM and X-ray diffraction. The thickness of the barrier layer of the porous oxide film was thin and it attributed to the formation of the metal particles, while the formation of the oxide precursor was associated with the surface pits which were developed in the pretreatment of Al.

  17. Exposure to Ultrafine Particles from Ambient Air and Oxidative Stress-Induced DNA Damage

    DEFF Research Database (Denmark)

    Bräuner, Elvira Vaclavik; Forchhammer, Lykke; Møller, Peter

    2007-01-01

    BACKGROUND: Particulate matter, especially ultrafine particles (UFPs), may cause health effects through generation of oxidative stress, with resulting damage to DNA and other macromolecules. OBJECTIVE: We investigated oxidative damage to DNA and related repair capacity in peripheral blood...... mononuclear cells (PBMCs) during controlled exposure to urban air particles with assignment of number concentration (NC) to four size modes with average diameters of 12, 23, 57, and 212 nm. DESIGN. Twenty-nine healthy adults participated in a randomized, two-factor cross-over study with or without biking...... exercise for 180 min and with exposure to particles (NC 6169-15362/cm3) or filtered air (NC 91-542/cm3) for 24 hr. METHODS: The levels of DNA strand breaks (SBs), oxidized purines as formamidopyrimidine DNA glycolase (FPG) sites, and activity of 7,8-dihydro-8-oxoguanine-DNA glycosylase (OGG1) in PBMCs were...

  18. Mechanism of formation of metal sulfide ultrafine particles in reverse micelles using a gas injection method

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Hiroshi; Tsubaki, Yoritaka; Hirai, Takayuki; Komasawa, Isao [Osaka Univ., Toyonaka, Osaka (Japan)

    1997-01-01

    The mechanism of formation of ultrafine CdS, ZnS, and their composite particles by the injection of H{sub 2}S into reverse micelles was studied. The particle formation process was followed by the change in UV-visible absorption spectra. The kinetics of the whole process including dissolution of H{sub 2}S, nucleation, particle growth, and coagulation was analyzed from time-course changes of the size and number of formed particles. The dissolution of H{sub 2}S was the principal rate-determining step, and most of the dissolved H{sub 2}S was consumed for particle growth. The particles formed in the present gas injection method were larger in size than those in the previous solution-mixing method in most cases. A kinetic scheme based on the distribution of the species among the micelles was then proposed, and this successfully explained the particle growth. Composite particles of CdS and ZnS having mixed crystal or core-shell structures were also prepared, and the application of these particles as photocatalysts for the cleavage of water to generate H{sub 2} was then investigated.

  19. Removal of fine and ultrafine particles from indoor air environments by the unipolar ion emission

    Science.gov (United States)

    Uk Lee, Byung; Yermakov, Mikhail; Grinshpun, Sergey A.

    2004-09-01

    The continuous emission of unipolar ions was evaluated in order to determine its ability to remove fine and ultrafine particles from indoor air environments. The evolution of the indoor aerosol concentration and particle size distribution was measured in real time with the ELPI in a room-size (24.3 m3) test chamber where the ion emitter was operating. After the results were compared with the natural decay, the air cleaning factor was determined. The particle aerodynamic size range of ∼0.04-2 μm was targeted because it represents many bioaerosol agents that cause emerging diseases, as well as those that can be used for biological warfare or in the event of bioterrorism. The particle electric charge distribution (also measured in the test chamber with the ELPI) was rapidly affected by the ion emission. It was concluded that the corona discharge ion emitters (either positive or negative), which are capable of creating an ion density of 105-106 e± cm-3, can be efficient in controlling fine and ultrafine aerosol pollutants in indoor air environments, such as a typical office or residential room. At a high ion emission rate, the particle mobility becomes sufficient so that the particle migration results in their deposition on the walls and other indoor surfaces. Within the tested ranges of the particle size and ion density, the particles were charged primarily due to the diffusion charging mechanism. The particle removal efficiency was not significantly affected by the particle size, while it increased with increasing ion emission rate and the time of emission. The performance characteristics of three commercially available ionic air purifiers, which produce unipolar ions by corona discharge at relatively high emission rates, were evaluated. A 30-minute operation of the most powerful device among those tested resulted in the removal of about 97% of 0.1 μm particles and about 95% of 1 μm particles from the air in addition to the natural decay effect.

  20. Ultrafine Particles from Traffic Emissions and Children’s Health (UPTECH in Brisbane, Queensland (Australia: Study Design and Implementation

    Directory of Open Access Journals (Sweden)

    Wafaa Nabil Ezz

    2015-02-01

    Full Text Available Ultrafine particles are particles that are less than 0.1 micrometres (µm in diameter. Due to their very small size they can penetrate deep into the lungs, and potentially cause more damage than larger particles. The Ultrafine Particles from Traffic Emissions and Children’s Health (UPTECH study is the first Australian epidemiological study to assess the health effects of ultrafine particles on children’s health in general and peripheral airways in particular. The study is being conducted in Brisbane, Australia. Continuous indoor and outdoor air pollution monitoring was conducted within each of the twenty five participating school campuses to measure particulate matter, including in the ultrafine size range, and gases. Respiratory health effects were evaluated by conducting the following tests on participating children at each school: spirometry, forced oscillation technique (FOT and multiple breath nitrogen washout test (MBNW (to assess airway function, fraction of exhaled nitric oxide (FeNO, to assess airway inflammation, blood cotinine levels (to assess exposure to second-hand tobacco smoke, and serum C-reactive protein (CRP levels (to measure systemic inflammation. A pilot study was conducted prior to commencing the main study to assess the feasibility and reliably of measurement of some of the clinical tests that have been proposed for the main study. Air pollutant exposure measurements were not included in the pilot study.

  1. Experimental investigation of submicron and ultrafine soot particle removal by tree leaves

    Science.gov (United States)

    Hwang, Hee-Jae; Yook, Se-Jin; Ahn, Kang-Ho

    2011-12-01

    Soot particles emitted from vehicles are one of the major sources of air pollution in urban areas. In this study, five kinds of trees were selected as Pinus densiflora, Taxus cuspidata, Platanus occidentalis, Zelkova serrata, and Ginkgo biloba, and the removal of submicron (densiflora showed the greatest deposition velocity, followed by T. cuspidata, Platanus occidentalis, Zelkova serrata, and Ginkgo biloba. In addition, from the comparison of deposition velocity between two groups of Platanus occidentalis leaves, i.e. one group of leaves with front sides only and the other with back sides only, it was supposed in case of the broadleaf trees that the removal of airborne soot particles of submicron and ultrafine sizes could be affected by the surface roughness of tree leaves, i.e. the veins and other structures on the leaves.

  2. Characteristics of Ultrafine Particles and Their Relationships with Meteorological Factors and Trace Gases in Wuhan, Central China

    Directory of Open Access Journals (Sweden)

    Tianhao Zhang

    2016-07-01

    Full Text Available Ultrafine particles with a diameter below 1 μm are strongly linked to traffic and industrial emissions, causing a growing global health concern. In order to reveal the characteristics of ultrafine particles in central China, which makes up the sparse research in industrial cities of a developing country, particle number concentrations (PNC together with meteorological parameters and concentrations of trace gases were measured over one year in Wuhan. The number concentration of ultrafine particles peaked in winter and was the lowest in summer across the entire size range monitored. Further, particles with a diameter smaller than 30 nm increased dramatically in concentration with decreasing diameter. The monthly averaged number concentrations of particles discriminated in three size ranges formed a near- inverse parabolic distribution peaking in January. This trend is supported by a negative correlation between PNC and precipitation, temperature, and mixing layer height, which emphasizes the effect of these meteorological parameters on scouring, convection, and diffusion of particles. However, since wind not only disperses particulate matter but also brings in exogenous particles, wind speed plays an equivocal role in particle number concentrations. The diurnal analysis indicates that hourly measurements of trace gases concentrations could be used as a proxy for dense industrial activities and to reveal some complex chemical reactions. The results of this study offer reasonable estimations of particle impacts and provide references for policymaking of emission control in the industrial cities of developing countries.

  3. The role of organic condensation on ultrafine particle growth during nucleation events

    Directory of Open Access Journals (Sweden)

    D. Patoulias

    2014-12-01

    Full Text Available A new aerosol dynamics model (DMANx has been developed that simulates the aerosol size/composition distribution and includes the condensation of organic vapors on nanoparticles through the implementation of the recently developed Volatility Basis Set framework. Simulations were performed for Hyytiala (Finland and Finokalia (Greece, two locations with different organic sources where detailed measurements were available to constrain the new model. We investigate the effect of condensation of organics and chemical aging reactions of secondary organic aerosol (OA on ultrafine particle growth and particle number concentration. This work highlights the importance of the pathways of oxidation of biogenic volatile organic compounds and the production of extremely low-volatility organics. At Hyytiala, organic condensation dominates the growth process of new particles. The low-volatility secondary OA contributes to particle growth during the early growth stage, but after a few hours most of the growth is due to semi-volatile secondary OA. At Finokalia, simulations show that organics have a complementary role to new particle growth contributing 45% to the total mass of new particles. Condensation of organics increases the number concentration of particles that can act as CCN (N100 by 13% at Finokalia and 25% at Hyytiala. The sensitivity of our results to the surface tension used is discussed.

  4. Modelling component evaporation and composition change of traffic-induced ultrafine particles during travel from street canyon to urban background.

    Science.gov (United States)

    Nikolova, Irina; MacKenzie, A Rob; Cai, Xiaoming; Alam, Mohammed S; Harrison, Roy M

    2016-07-18

    We developed a model (CiTTy-Street-UFP) of traffic-related particle behaviour in a street canyon and in the nearby downwind urban background that accounts for aerosol dynamics and the variable vapour pressure of component organics. The model simulates the evolution and fate of traffic generated multicomponent ultrafine particles (UFP) composed of a non-volatile core and 17 Semi-Volatile Organic Compounds (SVOC, modelled as n-alkane proxies). A two-stage modelling approach is adopted: (1) a steady state simulation inside the street canyon is achieved, in which there exists a balance between traffic emissions, condensation/evaporation, deposition, coagulation and exchange with the air above roof-level; and (2) a continuing simulation of the above-roof air parcel advected to the nearby urban park during which evaporation is dominant. We evaluate the component evaporation and associated composition changes of multicomponent organic particles in realistic atmospheric conditions and compare our results with observations from London (UK) in a street canyon and an urban park. With plausible input conditions and parameter settings, the model can reproduce, with reasonable fidelity, size distributions in central London in 2007. The modelled nucleation-mode peak diameter, which is 23 nm in the steady-state street canyon, decreases to 9 nm in a travel time of just 120 s. All modelled SVOC in the sub-10 nm particle size range have evaporated leaving behind only non-volatile material, whereas modelled particle composition in the Aitken mode contains SVOC between C26H54 and C32H66. No data on particle composition are available in the study used for validation, or elsewhere. Measurements addressing in detail the size resolved composition of the traffic emitted UFP in the atmosphere are a high priority for future research. Such data would improve the representation of these particles in dispersion models and provide the data essential for model validation. Enhanced knowledge of the

  5. Ultrafine and fine particle formation in a naturally ventilated office as a result of reactions between ozone and scented products

    DEFF Research Database (Denmark)

    Toftum, Jørn; Dijken, F. v.

    2003-01-01

    occurring in such offices, air fresheners or scented cleaners may react with ozone to form secondary organic aerosols (SOA). The tested air fresheners were relatively small sources of SOA with detectable increases occurring only in the ultrafine particle number concentration. With the cleaner, also...

  6. Ultrafine particles dispersion modeling in a street canyon: development and evaluation of a composite lattice Boltzmann model.

    Science.gov (United States)

    Habilomatis, George; Chaloulakou, Archontoula

    2013-10-01

    Recently, a branch of particulate matter research concerns on ultrafine particles found in the urban environment, which originate, to a significant extent, from traffic sources. In urban street canyons, dispersion of ultrafine particles affects pedestrian's short term exposure and resident's long term exposure as well. The aim of the present work is the development and the evaluation of a composite lattice Boltzmann model to study the dispersion of ultrafine particles, in urban street canyon microenvironment. The proposed model has the potential to penetrate into the physics of this complex system. In order to evaluate the model performance against suitable experimental data, ultrafine particles levels have been monitored on an hourly basis for a period of 35 days, in a street canyon, in Athens area. The results of the comparative analysis are quite satisfactory. Furthermore, our modeled results are in a good agreement with the results of other computational and experimental studies. This work is a first attempt to study the dispersion of an air pollutant by application of the lattice Boltzmann method.

  7. Ultrafine particle size distributions near freeways: Effects of differing wind directions on exposure

    Science.gov (United States)

    Kozawa, Kathleen H.; Winer, Arthur M.; Fruin, Scott A.

    2012-12-01

    High ambient ultrafine particle (UFP) concentrations may play an important role in the adverse health effects associated with living near busy roadways. However, UFP size distributions change rapidly as vehicle emissions dilute and age. These size changes can influence UFP lung deposition rates and dose because deposition in the respiratory system is a strong function of particle size. Few studies to date have measured and characterized changes in near-road UFP size distributions in real-time, thus missing transient variations in size distribution due to short-term fluctuations in wind speed, direction, or particle dynamics. In this study we measured important wind direction effects on near-freeway UFP size distributions and gradients using a mobile platform with 5-s time resolution. Compared to more commonly measured perpendicular (downwind) conditions, parallel wind conditions appeared to promote formation of broader and larger size distributions of roughly one-half the particle concentration. Particles during more parallel wind conditions also changed less in size with downwind distance and the fraction of lung-deposited particle number was calculated to be 15% lower than for downwind conditions, giving a combined decrease of about 60%. In addition, a multivariate analysis of several variables found meteorology, particularly wind direction and temperature, to be important in predicting UFP concentrations within 150 m of a freeway (R2 = 0.46, p = 0.014).

  8. Variability in exposure to ambient ultrafine particles in urban schools: Comparative assessment between Australia and Spain.

    Science.gov (United States)

    Mazaheri, Mandana; Reche, Cristina; Rivas, Ioar; Crilley, Leigh R; Álvarez-Pedrerol, Mar; Viana, Mar; Tobias, Aurelio; Alastuey, Andrés; Sunyer, Jordi; Querol, Xavier; Morawska, Lidia

    2016-03-01

    Ambient ultrafine particle number concentrations (PNC) have inhomogeneous spatio-temporal distributions and depend on a number of different urban factors, including background conditions and distant sources. This paper quantitatively compares exposure to ambient ultrafine particles at urban schools in two cities in developed countries, with high insolation climatic conditions, namely Brisbane (Australia) and Barcelona (Spain). The analysis used comprehensive indoor and outdoor air quality measurements at 25 schools in Brisbane and 39 schools in Barcelona. PNC modes were analysed with respect to ambient temperature, land use and urban characteristics, combined with the measured elemental carbon concentrations, NOx (Brisbane) and NO2 (Barcelona). The trends and modes of the quantified weekday average daily cycles of ambient PNC exhibited significant differences between the two cities. PNC increases were observed during traffic rush hours in both cases. However, the mid-day peak was dominant in Brisbane schools and had the highest contribution to total PNC for both indoors and outdoors. In Barcelona, the contribution from traffic was highest for ambient PNC, while the mid-day peak had a slightly higher contribution for indoor concentrations. Analysis of the relationships between PNC and land use characteristics in Barcelona schools showed a moderate correlation with the percentage of road network area and an anti-correlation with the percentage of green area. No statistically significant correlations were found for Brisbane. Overall, despite many similarities between the two cities, school-based exposure patterns were different. The main source of ambient PNC at schools was shown to be traffic in Barcelona and mid-day new particle formation in Brisbane. The mid-day PNC peak in Brisbane could have been driven by the combined effect of background and meteorological conditions, as well as other local/distant sources. The results have implications for urban development

  9. Size-Resolved Source Emission Rates of Indoor Ultrafine Particles Considering Coagulation.

    Science.gov (United States)

    Rim, Donghyun; Choi, Jung-Il; Wallace, Lance A

    2016-09-20

    Indoor ultrafine particles (UFP, log-normally distributed for three common indoor UFP sources: an electric stove, a natural gas burner, and a paraffin wax candle. Experimental investigations were performed in a full-scale test building. Size- and time-resolved concentrations of UFP ranging from 2 to 100 nm were monitored using a scanning mobility particle sizer (SMPS). Based on the temporal evolution of the particle size distribution during the source emission period, the size-dependent source emission rate was determined using a material-balance modeling approach. The results indicate that, for a given UFP source, the source strength varies with particle size and source type. The analytical model assuming a log-normally distributed source emission rate could predict the temporal evolution of the particle size distribution with reasonable accuracy for the gas stove and the candle. Including the effect of coagulation was found to increase the estimates of source strengths by up to a factor of 8. This result implies that previous studies on indoor UFP source strengths considering only deposition and ventilation might have largely underestimated the true values of UFP source strengths, especially for combustion due to the natural gas stove and the candle.

  10. Occupational Exposure to Ultrafine Particles among Airport Employees - Combining Personal Monitoring and Global Positioning System

    DEFF Research Database (Denmark)

    Møller, Karina Lauenborg; Thygesen, Lau Caspar; Schipperijn, Jasper

    2014-01-01

    BACKGROUND: Exposure to ultrafine particles (UFP) has been linked to cardiovascular and lung diseases. Combustion of jet fuel and diesel powered handling equipment emit UFP resulting in potentially high exposure levels among employees working at airports. High levels of UFP have been reported...... at several airports, especially on the apron, but knowledge on individual exposure profiles among different occupational groups working at an airport is lacking. PURPOSE: The aim of this study was to compare personal exposure to UFP among five different occupational groups working at Copenhagen Airport (CPH...... concentrations (GM: 12 to 20×103 UFP/cm3). CONCLUSION: The study demonstrates a strong gradient of exposure to UFP in ambient air across occupational groups of airport employees....

  11. Estimates of HVAC filtration efficiency for fine and ultrafine particles of outdoor origin

    Science.gov (United States)

    Azimi, Parham; Zhao, Dan; Stephens, Brent

    2014-12-01

    This work uses 194 outdoor particle size distributions (PSDs) from the literature to estimate single-pass heating, ventilating, and air-conditioning (HVAC) filter removal efficiencies for PM2.5 and ultrafine particles (UFPs: HVAC filters identified in the literature. Filters included those with a minimum efficiency reporting value (MERV) of 5, 6, 7, 8, 10, 12, 14, and 16, as well as HEPA filters. We demonstrate that although the MERV metric defined in ASHRAE Standard 52.2 does not explicitly account for UFP or PM2.5 removal efficiency, estimates of filtration efficiency for both size fractions increased with increasing MERV. Our results also indicate that outdoor PSD characteristics and assumptions for particle density and typical size-resolved infiltration factors (in the absence of HVAC filtration) do not drastically impact estimates of HVAC filter removal efficiencies for PM2.5. The impact of these factors is greater for UFPs; however, they are also somewhat predictable. Despite these findings, our results also suggest that MERV alone cannot always be used to predict UFP or PM2.5 removal efficiency given the various size-resolved removal efficiencies of different makes and models, particularly for MERV 7 and MERV 12 filters. This information improves knowledge of how the MERV designation relates to PM2.5 and UFP removal efficiency for indoor particles of outdoor origin. Results can be used to simplify indoor air quality modeling efforts and inform standards and guidelines.

  12. Performance of school bus retrofit systems: ultrafine particles and other vehicular pollutants.

    Science.gov (United States)

    Zhang, Qunfang; Zhu, Yifang

    2011-08-01

    This study evaluated the performance of retrofit systems for diesel-powered school buses, a diesel oxidation catalyst (DOC) muffler and a spiracle crankcase filtration system (CFS), regarding ultrafine particles (UFPs) and other air pollutants from tailpipe emissions and inside bus cabins. Tailpipe emissions and in-cabin air pollutant levels were measured before and after retrofitting when the buses were idling and during actual pick-up/drop off routes. Retrofit systems significantly reduced tailpipe emissions with a reduction of 20-94% of total particles with both DOC and CFS installed. However, no unequivocal decrease was observed for in-cabin air pollutants after retrofitting. The AC/fan unit and the surrounding air pollutant concentrations played more important roles for determining the in-cabin air quality of school buses than did retrofit technologies. Although current retrofit systems reduce children's exposure while waiting to board at a bus station, retrofitting by itself does not protect children satisfactorily from in-cabin particle exposures. Turning on the bus engine increased in-cabin UFP levels significantly only when the wind blew from the bus' tailpipe toward its hood with its windows open. This indicated that wind direction and window position are significant factors determining how much self-released tailpipe emissions may penetrate into the bus cabin. The use of an air purifier was found to remove in-cabin particles by up to 50% which might be an alternative short-to-medium term strategy to protect children's health.

  13. Ultrafine Sm-Fe-N Particles Prepared by Planetary Ball Milling

    Directory of Open Access Journals (Sweden)

    Neil D.

    2013-01-01

    Full Text Available Ultrafine magnetically hard particles are needed for the bottom­up fabrication of anisotropic exchanged­coupled permanent magnets. In this study we have chosen Sm2Fe17Nx because of its high anisotropy field and large saturation magnetization. A multi­stage planetary ball milling process was used. The key is to find the right balance of energy used to mill the precursor particles; it must be high enough to break the particles and reduce their size but, not so high as to destroy the crystal structure of the nanoparticles that would lead to deterioration of the magnetic properties. First the coarse powders were subjected to a wet milling with 2.0 mm diameter media. In each subsequent stage the media size was reduced to maintain the milling balance. Using such a process produced particles in a size range from 100 - 800 nm with a coercivity as high as 10 kOe at room temperature.

  14. Emission characteristics of ultrafine particles and volatile organic compounds in a commercial printing center.

    Science.gov (United States)

    Betha, Raghu; Selvam, Valliappan; Blake, Donald R; Balasubramanian, Rajasekhar

    2011-11-01

    Laser printers are one of the common indoor equipment in schools, offices, and various other places. Laser printers have recently been identified as a potential source of indoor air pollution. This study examines the characteristics of ultrafine particles (UFPs, diameter commercial printing center. The results indicated that apart from the printer type, the age of printers, and the number of pages printed, the characteristics of UFPs emitted from printers also depend on indoor ventilation conditions. It was found that at reduced ventilation rates of indoor air, there was a rise in the number concentration of UFPs in the printing center. Interestingly, the contribution of UFPs to the total number of submicrometer-sized particles was observed to be higher at a sampling point far away from the printer than the one in the immediate vicinity of the printer. Black carbon (BC) measurements showed a good correlation (rs = 0.82) with particles in the size range of 100-560 nm than those with diameters less than 100 nm (rs = 0.33 for 50-100 nm, and rs = -0.19 for 5.6-50 nm particles). Measurements of VOCs in the printing center showed high levels of m-, o-, and p-xylene, styrene, and ethylbenzenes during peak hours of printing. Although toluene was found in higher levels, its concentration decreased during peak hours compared to those during nonoperating hours of the printing center.

  15. Magnetic property and microstructure of single crystalline Nd2Fe14B ultrafine particles ball milled from HDDR powders

    Energy Technology Data Exchange (ETDEWEB)

    Li, WF; Hu, XC; Cui, BZ; Yang, JB; Han, JZ; Hadjipanayis, GC

    2013-08-01

    In this work we report the microstructure and magnetic property of single crystalline Nd2Fe14B ultrafine particles ball milled from HDDR Nd-Fe-B alloys. The average size of the particles is 283 nm, and TEM observation reveals that these particles are single crystalline. The coercivity of these particles is 6.0 kOe, which is much higher than that of the particles ball milled from sintered and hot pressed Nd-Fe-B magnets. Micromagnetic analysis shows that the coercivity degradation is caused by surface damage during ball milling. (C) 2013 Elsevier B.V. All rights reserved.

  16. Comparison of Three Real-Time Measurement Methods for Airborne Ultrafine Particles in the Silicon Alloy Industry

    Directory of Open Access Journals (Sweden)

    Ida Teresia Kero

    2016-09-01

    Full Text Available The aim of this study was to compare the applicability and the correlation between three commercially available instruments capable of detection, quantification, and characterization of ultrafine airborne particulate matter in the industrial setting of a tapping area in a silicon alloy production plant. The number concentration of ultrafine particles was evaluated using an Electric Low Pressure Impactor (ELPITM, a Fast Mobility Particle Sizer (FMPSTM, and a Condensation Particle Counter (CPC. The results are discussed in terms of particle size distribution and temporal variations linked to process operations. The instruments show excellent temporal covariation and the correlation between the FMPS and ELPI is good. The advantage of the FMPS is the excellent time- and size resolution of the results. The main advantage of the ELPI is the possibility to collect size-fractionated samples of the dust for subsequent analysis by, for example, electron microscopy. The CPC does not provide information about the particle size distribution and its correlation to the other two instruments is somewhat poor. Nonetheless, the CPC gives basic, real-time information about the ultrafine particle concentration and can therefore be used for source identification.

  17. Comparison of Three Real-Time Measurement Methods for Airborne Ultrafine Particles in the Silicon Alloy Industry.

    Science.gov (United States)

    Kero, Ida Teresia; Jørgensen, Rikke Bramming

    2016-01-01

    The aim of this study was to compare the applicability and the correlation between three commercially available instruments capable of detection, quantification, and characterization of ultrafine airborne particulate matter in the industrial setting of a tapping area in a silicon alloy production plant. The number concentration of ultrafine particles was evaluated using an Electric Low Pressure Impactor (ELPI(TM)), a Fast Mobility Particle Sizer (FMPS(TM)), and a Condensation Particle Counter (CPC). The results are discussed in terms of particle size distribution and temporal variations linked to process operations. The instruments show excellent temporal covariation and the correlation between the FMPS and ELPI is good. The advantage of the FMPS is the excellent time- and size resolution of the results. The main advantage of the ELPI is the possibility to collect size-fractionated samples of the dust for subsequent analysis by, for example, electron microscopy. The CPC does not provide information about the particle size distribution and its correlation to the other two instruments is somewhat poor. Nonetheless, the CPC gives basic, real-time information about the ultrafine particle concentration and can therefore be used for source identification.

  18. Comparison of Three Real-Time Measurement Methods for Airborne Ultrafine Particles in the Silicon Alloy Industry

    Science.gov (United States)

    Kero, Ida Teresia; Jørgensen, Rikke Bramming

    2016-01-01

    The aim of this study was to compare the applicability and the correlation between three commercially available instruments capable of detection, quantification, and characterization of ultrafine airborne particulate matter in the industrial setting of a tapping area in a silicon alloy production plant. The number concentration of ultrafine particles was evaluated using an Electric Low Pressure Impactor (ELPITM), a Fast Mobility Particle Sizer (FMPSTM), and a Condensation Particle Counter (CPC). The results are discussed in terms of particle size distribution and temporal variations linked to process operations. The instruments show excellent temporal covariation and the correlation between the FMPS and ELPI is good. The advantage of the FMPS is the excellent time- and size resolution of the results. The main advantage of the ELPI is the possibility to collect size-fractionated samples of the dust for subsequent analysis by, for example, electron microscopy. The CPC does not provide information about the particle size distribution and its correlation to the other two instruments is somewhat poor. Nonetheless, the CPC gives basic, real-time information about the ultrafine particle concentration and can therefore be used for source identification. PMID:27598180

  19. Electrosurgical Smoke: Ultrafine Particle Measurements and Work Environment Quality in Different Operating Theatres

    Science.gov (United States)

    Romano, Francesco; Gustén, Jan; De Antonellis, Stefano; Joppolo, Cesare M.

    2017-01-01

    Air cleanliness in operating theatres (OTs) is an important factor for preserving the health of both the patient and the medical staff. Particle contamination in OTs depends mainly on the surgery process, ventilation principle, personnel clothing systems and working routines. In many open surgical operations, electrosurgical tools (ESTs) are used for tissue cauterization. ESTs generate a significant airborne contamination, as surgical smoke. Surgical smoke is a work environment quality problem. Ordinary surgical masks and OT ventilation systems are inadequate to control this problem. This research work is based on numerous monitoring campaigns of ultrafine particle concentrations in OTs, equipped with upward displacement ventilation or with a downward unidirectional airflow system. Measurements performed during ten real surgeries highlight that the use of ESTs generates a quite sharp and relevant increase of particle concentration in the surgical area as well within the entire OT area. The measured contamination level in the OTs are linked to surgical operation, ventilation principle, and ESTs used. A better knowledge of airborne contamination is crucial for limiting the personnel’s exposure to surgical smoke. Research results highlight that downward unidirectional OTs can give better conditions for adequate ventilation and contaminant removal performances than OTs equipped with upward displacement ventilation systems. PMID:28146089

  20. Characterization of decay and emission rates of ultrafine particles in indoor ice rink.

    Science.gov (United States)

    Kim, J; Lee, K

    2013-08-01

    The purposes of this study were to determine indoor ultrafine particle (UFP, diameter DiSCmini were 0.54 ± 0.21/h and 0.85 ± 0.34/h, respectively. The average decay rate of UFP surface area concentration was 0.33 ± 0.15/h. The average emission rates of UFP number concentrations measured by P-Trak and DiSCmini were 1.2 × 10(14) ± 6.5 × 10(13) particles/min and 3.3 × 10(14) ± 2.4 × 10(14) particles/min, respectively. The average emission rate of UFP surface area concentration was 3.1 × 10(11) ± 2.0 × 10(11) μm(2)/min. UFP emission rate was associated with resurfacer age. DiSCmini measured higher decay and emission rates than P-Trak due to their different measuring mechanisms and size ranges.

  1. Electrosurgical Smoke: Ultrafine Particle Measurements and Work Environment Quality in Different Operating Theatres

    Directory of Open Access Journals (Sweden)

    Francesco Romano

    2017-01-01

    Full Text Available Air cleanliness in operating theatres (OTs is an important factor for preserving the health of both the patient and the medical staff. Particle contamination in OTs depends mainly on the surgery process, ventilation principle, personnel clothing systems and working routines. In many open surgical operations, electrosurgical tools (ESTs are used for tissue cauterization. ESTs generate a significant airborne contamination, as surgical smoke. Surgical smoke is a work environment quality problem. Ordinary surgical masks and OT ventilation systems are inadequate to control this problem. This research work is based on numerous monitoring campaigns of ultrafine particle concentrations in OTs, equipped with upward displacement ventilation or with a downward unidirectional airflow system. Measurements performed during ten real surgeries highlight that the use of ESTs generates a quite sharp and relevant increase of particle concentration in the surgical area as well within the entire OT area. The measured contamination level in the OTs are linked to surgical operation, ventilation principle, and ESTs used. A better knowledge of airborne contamination is crucial for limiting the personnel’s exposure to surgical smoke. Research results highlight that downward unidirectional OTs can give better conditions for adequate ventilation and contaminant removal performances than OTs equipped with upward displacement ventilation systems.

  2. Filter performance of n99 and n95 facepiece respirators against viruses and ultrafine particles.

    Science.gov (United States)

    Eninger, Robert M; Honda, Takeshi; Adhikari, Atin; Heinonen-Tanski, Helvi; Reponen, Tiina; Grinshpun, Sergey A

    2008-07-01

    The performance of three filtering facepiece respirators (two models of N99 and one N95) challenged with an inert aerosol (NaCl) and three virus aerosols (enterobacteriophages MS2 and T4 and Bacillus subtilis phage)-all with significant ultrafine components-was examined using a manikin-based protocol with respirators sealed on manikins. Three inhalation flow rates, 30, 85, and 150 l min(-1), were tested. The filter penetration and the quality factor were determined. Between-respirator and within-respirator comparisons of penetration values were performed. At the most penetrating particle size (MPPS), >3% of MS2 virions penetrated through filters of both N99 models at an inhalation flow rate of 85 l min(-1). Inhalation airflow had a significant effect upon particle penetration through the tested respirator filters. The filter quality factor was found suitable for making relative performance comparisons. The MPPS for challenge aerosols was 0.1 mum. The filtration performance of the N95 respirator approached that of the two models of N99 over the range of particle sizes tested ( approximately 0.02 to 0.5 mum). Filter penetration of the tested biological aerosols did not exceed that of inert NaCl aerosol. The results suggest that inert NaCl aerosols may generally be appropriate for modeling filter penetration of similarly sized virions.

  3. The rural carbonaceous aerosols in coarse, fine, and ultrafine particles during haze pollution in northwestern China.

    Science.gov (United States)

    Zhu, Chong-Shu; Cao, Jun-Ji; Tsai, Chuen-Jinn; Shen, Zhen-Xing; Liu, Sui-Xin; Huang, Ru-Jin; Zhang, Ning-ning; Wang, Ping

    2016-03-01

    The carbonaceous aerosol concentrations in coarse particle (PM10: Dp ≤ 10 μm, particulate matter with an aerodynamic diameter less than 10 μm), fine particle (PM2.5: Dp ≤ 2.5 μm), and ultrafine particle (PM0.133: Dp ≤ 0.133 μm) carbon fractions in a rural area were investigated during haze events in northwestern China. The results indicated that PM2.5 contributed a large fraction in PM10. OC (organic carbon) accounted for 33, 41, and 62 % of PM10, PM2.5, and PM0.133, and those were 2, 2.4, and 0.4 % for EC (elemental carbon) in a rural area, respectively. OC3 was more abundant than other organic carbon fractions in three PMs, and char dominated EC in PM10 and PM2.5 while soot dominated EC in PM0.133. The present study inferred that K(+), OP, and OC3 are good biomass burning tracers for rural PM10 and PM2.5, but not for PM0.133 during haze pollution. Our results suggest that biomass burning is likely to be an important contributor to rural PMs in northwestern China. It is necessary to establish biomass burning control policies for the mitigation of severe haze pollution in a rural area.

  4. Simulation on a novel micron-array inertial impactor for submicron and ultrafine particle separation

    Science.gov (United States)

    Liu, Rui-Tao; Tao, Lu-Qi; Yang, Yi; Ren, Tian-Ling

    2016-08-01

    The particulate matter (PM), which was put forward in 1997 by US, had taken more and more attention due to the influence on human health. Although the mass concentration, number concentration and chemical composition of PM were still major research directions, how to collect these PMs more efficiently becomes critical. Inertial impactor is an effective separation device, however, due to different motion states of PM2.5 and PM0.3 in the flow field, the inertial impactor which can separate PM0.3 from other PMs has not been fabricated. In this work, the motion states for both submicron and ultrafine particles were studied by using classical theory of channel aerodynamic, and a novel micron-array inertial impactor was designed and simulated for the first time. Besides, the influence of some characteristic parameters (W, T, S, Dc, etc.) on particle collection efficiency were researched and discussed through simulation results. This novel structure can be easily fabricated by MEMS technology or laser direct writing and also can be widely used in particle separation or flexible sensor fields.

  5. Alterations in welding process voltage affect the generation of ultrafine particles, fume composition, and pulmonary toxicity.

    Science.gov (United States)

    Antonini, James M; Keane, Michael; Chen, Bean T; Stone, Samuel; Roberts, Jenny R; Schwegler-Berry, Diane; Andrews, Ronnee N; Frazer, David G; Sriram, Krishnan

    2011-12-01

    The goal was to determine if increasing welding voltage changes the physico-chemical properties of the fume and influences lung responses. Rats inhaled 40 mg/m³ (3 h/day × 3 days) of stainless steel (SS) welding fume generated at a standard voltage setting of 25 V (regular SS) or at a higher voltage (high voltage SS) of 30 V. Particle morphology, size and composition were characterized. Bronchoalveolar lavage was performed at different times after exposures to assess lung injury. Fumes collected from either of the welding conditions appeared as chain-like agglomerates of nanometer-sized primary particles. High voltage SS welding produced a greater number of ultrafine-sized particles. Fume generated by high voltage SS welding was higher in manganese. Pulmonary toxicity was more substantial and persisted longer after exposure to the regular SS fume. In summary, a modest raise in welding voltage affected fume size and elemental composition and altered the temporal lung toxicity profile.

  6. Coarse and fine particles but not ultrafine particles in urban air trigger hospital admission for asthma in children

    DEFF Research Database (Denmark)

    Iskandar, Amne; Andersen, Zorana Jovanovic; Bønnelykke, Klaus;

    2012-01-01

    BackgroundShort-term exposure to air pollution can trigger hospital admissions for asthma in children, but it is not known which components of air pollution are most important. There are no available studies on the particular effect of ultrafine particles (UFPs) on paediatric admissions for asthma......(x)) or nitrogen dioxide (NO(2)); and (2) infants are more susceptible to the effects of exposure to air pollution than older children.MethodDaily counts of admissions for asthma in children aged 0-18 years to hospitals located within a 15 km radius of the central fixed background urban air pollution measurement...... station in Copenhagen between 2001 and 2008 were extracted from the Danish National Patient Registry. A time-stratified case crossover design was applied and data were analysed using conditional logistic regression to estimate the effect of air pollution on asthma admissions.ResultsA significant...

  7. Air pollutant concentrations near three Texas roadways, Part I: Ultrafine particles

    Science.gov (United States)

    Zhu, Yifang; Pudota, Jayanth; Collins, Donald; Allen, David; Clements, Andrea; DenBleyker, Allison; Fraser, Matt; Jia, Yuling; McDonald-Buller, Elena; Michel, Edward

    Vehicular emitted air pollutant concentrations were studied near three types of roadways in Austin, Texas: (1) State Highway 71 (SH-71), a heavily traveled arterial highway dominated by passenger vehicles; (2) Interstate 35 (I-35), a limited access highway north of Austin in Georgetown; and (3) Farm to Market Road 973 (FM-973), a heavily traveled surface roadway dominated by truck traffic. Air pollutants examined include carbon monoxide (CO), oxides of nitrogen (NO x), and carbonyl species in the gas-phase. In the particle phase, ultrafine particle (UFP) concentrations (diameter duty traffic, wind speed, and proximity to the road were found to be the most important factors determining UFP concentrations near the roadways. Since wind directions were not consistent during the sampling periods, distances along wind trajectories from the roadway to the sampling points were used to study the decay characteristics of UFPs. Under perpendicular wind conditions, for all studied roadway types, particle number concentrations increased dramatically moving from the upwind side to the downwind side. The elevated particle number concentrations decay exponentially with increasing distances from the roadway with sharp concentration gradients observed within 100-150 m, similar to previously reported studies. A single exponential decay curve was found to fit the data collected from all three roadways very well under perpendicular wind conditions. No consistent pattern was observed for UFPs under parallel wind conditions. However, regardless of wind conditions, particle concentrations returned to background levels within a few hundred meters of the roadway. Within measured UFP size ranges, smaller particles (6-25 nm) decayed faster than larger ones (100-300 nm). Similar decay rates were observed among UFP number, surface, and volume.

  8. Continuous Near-Road Monitoring of Ultrafine Particles from 2010-2015 in Toronto, Canada

    Science.gov (United States)

    Su, Y.; Sofowote, U.; Debosz, J.; Munoz, T.

    2015-12-01

    Ultrafine particles (UFPs) have an aerodynamic diameter less than 100 nanometre (nm). Their large surface areas per unit mass favor absorption of toxic chemicals in air. UFPs could penetrate deep into the respiratory or cardiovascular systems and pose adverse health effects. Recent studies showed the association between children exposure to UFPs and their systolic blood pressure. In urban environments, primary sources of UFPs are from road traffic emissions and account for most of the total particle numbers. Controls on UPFs rely on better understanding of their emission sources and environmental behaviour. Ontario Ministry of the Environment and Climate Change have monitored UFPs since 2010 at two near-road stations in Toronto by using TSI 3031 UFP monitors. One station is located in mixed residential and industrial area and 16 meters from a major road with over 20,000 vehicles per day. The other station is surrounded by mixed residential and commercial buildings and 20 meters from a major road with over 20,000 vehicles per day. UFPs concentrations were monitored using six size channels: 20-30nm, 30-50nm, 50-70nm, 70-100nm, 100-200nm, and 200-450nm. The TSI 3031 monitors generally performed well for long-term UFP monitoring. Multi-year measurements of UFPs at the two stations show no apparent inter-annual variation or seasonality. Smaller particles (i.e., 20-50 nm) were found to be composed of over 50% of the measured particles. The observations are generally consistent with the theoretical understanding of particle nuclei mode and accumulation mode. When air mass originated from road traffic, UFPs were elevated in morning traffic hours and to a less extent in the late afternoon. The elevated UFPs number concentrations coincided with other traffic-related air pollutants like nitrogen oxides and black carbon. Moreover, higher number concentrations were found on weekdays than weekends. The observations suggest that UFPs are mostly from vehicle emissions.

  9. Exposure assessment of a cyclist to PM10 and ultrafine particles.

    Science.gov (United States)

    Berghmans, P; Bleux, N; Int Panis, L; Mishra, V K; Torfs, R; Van Poppel, M

    2009-02-01

    Estimating personal exposure to air pollution is a crucial component in identifying high-risk populations and situations. It will enable policy makers to determine efficient control strategies. Cycling is again becoming a favorite mode of transport both in developing and in developed countries due to increasing traffic congestion and environmental concerns. In Europe, it is also seen as a healthy sports activity. However, due to high levels of hazardous pollutants in the present day road microenvironment the cyclist might be at a higher health risk due to higher breathing rate and proximity to the vehicular exhaust. In this paper we present estimates of the exposure of a cyclist to particles of various size fractions including ultrafine particles (UFP) in the town of Mol (Flanders, Belgium). The results indicate relatively higher UFP concentration exposure during morning office hours and moderate UFP levels during afternoon. The major sources of UFP and PM(10) were identified, which are vehicular emission and construction activities, respectively. We also present a dust mapping technique which can be a useful tool for town planners and local policy makers.

  10. Characterization of ultrafine particle number concentration and new particle formation in an urban environment of Taipei, Taiwan

    Science.gov (United States)

    Cheung, H. C.; Chou, C. C.-K.; Huang, W.-R.; Tsai, C.-Y.

    2013-09-01

    An intensive aerosol characterization experiment was performed at the Taipei Aerosol and Radiation Observatory (TARO, 25.02° N, 121.53° E) in the urban area of Taipei, Taiwan, during July 2012. Number concentration and size distribution of aerosol particles were measured continuously, which were accompanied by concurrent measurements of mass concentration of submicron particles, PM1 (d ≤ 1 μm), and photolysis rate of ozone, J(O1D). The averaged number concentrations of total (Ntotal), accumulation mode (Nacu), Aitken mode (NAitken), and nucleation mode (Nnuc) particles were 13.9 × 103 cm-3, 1.2 × 103 cm-3, 6.1 × 103 cm-3, and 6.6 × 103 cm-3, respectively. Accordingly, the ultrafine particles (UFPs, d ≤ 100 nm) accounted for 91% of the total number concentration of particles measured in this study (10 ≤ d ≤ 429 nm), indicating the importance of UFPs to the air quality and radiation budget in Taipei and its surrounding areas. An averaged Nnuc / NOx ratio of 192.4 cm-3 ppbv-1 was derived from nighttime measurements, which was suggested to be the characteristic of vehicle emissions that contributed to the "urban background" of nucleation mode particles throughout a day. On the contrary, it was found that the number concentration of nucleation mode particles was independent of NOx and could be elevated up to 10 times of the "urban background" levels during daytime, suggesting a substantial amount of nucleation mode particles produced from photochemical processes. Averages (± 1σ) of the diameter growth rate (GR) and formation rate of nucleation mode particles, J10, were 11.9 ± 10.6 nm h-1 and 6.9 ± 3.0 cm-3 s-1, respectively. Consistency in the time series of the nucleation mode particle concentration and the proxy of H2SO4 production, UVB · SO2/CS, for new particle formation (NPF) events suggested that photooxidation of SO2 was likely one of the major mechanisms for the formation of new particles in our study area. Moreover, it was revealed that the

  11. Ultrafine Zinc and Nickel, Palladium, Silver Coated Zinc Particles Used for Reductive Dehalogenation of Chlorinated Ethylenes in Aqueous Solution

    OpenAIRE

    Li, Weifeng; Kenneth J. Klabunde

    1998-01-01

    Zero-valent zinc metal has been employed for the reductive dehalogenation of chlorinated ethylenes. In order to enhance this environmental remediation chemistry, ultrafine zinc particles and transition metal additives (coatings) have been employed. Indeed, activated zinc (cryozinc) significantly enhanced the reduction/dehalogenation process, especially in the presence of nickel and palladium coatings. These reagents were able to achieve rapid, deep reductive dehalogenation of trichloroethylen...

  12. Concentrations of fine, ultrafine, and black carbon particles in auto-rickshaws in New Delhi, India

    Science.gov (United States)

    Apte, Joshua, S.; Kirchstetter, Thomas W.; Reich, Alexander, H.; Deshpande, Shyam J.; Kaushik, Geetanjali; Chel, Arvind; Marshall, Julian D.; Nazaroff, William W.

    2011-08-01

    Concentrations of air pollutants from vehicles are elevated along roadways, indicating that human exposure in transportation microenvironments may not be adequately characterized by centrally located monitors. We report results from ˜180 h of real-time measurements of fine particle and black carbon mass concentration (PM 2.5, BC) and ultrafine particle number concentration (PN) inside a common vehicle, the auto-rickshaw, in New Delhi, India. Measured exposure concentrations are much higher in this study (geometric mean for ˜60 trip-averaged concentrations: 190 μg m -3 PM 2.5, 42 μg m -3 BC, 280 × 10 3 particles cm -3; GSD ˜1.3 for all three pollutants) than reported for transportation microenvironments in other megacities. In-vehicle concentrations exceeded simultaneously measured ambient levels by 1.5× for PM 2.5, 3.6× for BC, and 8.4× for PN. Short-duration peak concentrations (averaging time: 10 s), attributable to exhaust plumes of nearby vehicles, were greater than 300 μg m -3 for PM 2.5, 85 μg m -3 for BC, and 650 × 10 3 particles cm -3 for PN. The incremental increase of within-vehicle concentration above ambient levels—which we attribute to in- and near-roadway emission sources—accounted for 30%, 68% and 86% of time-averaged in-vehicle PM 2.5, BC and PN concentrations, respectively. Based on these results, we estimate that one's exposure during a daily commute by auto-rickshaw in Delhi is as least as large as full-day exposures experienced by urban residents of many high-income countries. This study illuminates an environmental health concern that may be common in many populous, low-income cities.

  13. The formation and growth of ultrafine particles in two contrasting environments: a case study

    Science.gov (United States)

    Kompalli, Sobhan Kumar; Babu, S. Suresh; Krishna Moorthy, K.; Gogoi, Mukunda M.; Nair, Vijayakumar S.; Chaubey, Jai Prakash

    2014-07-01

    Formation of ultrafine particles and their subsequent growth have been examined during new particle formation (NPF) events in two contrasting environments under varying ambient conditions, one for a tropical semi-urban coastal station, Trivandrum, and the other for a high-altitude free-tropospheric Himalayan location, Hanle. At Trivandrum, NPF bursts took place in the late evening/night hours, whereas at Hanle the burst was a daytime event. During the nucleation period, the total number concentration reached levels as high as ~ 15 900 cm-3 at Trivandrum, whereas at Hanle, the total number concentration was ~ 2700 cm-3, indicating the abundant availability of precursors at Trivandrum and the pristine nature of Hanle. A sharp decrease was associated with NPF for the geometric mean diameter of the size distribution, and a large increase in the concentration of the particles in the nucleation regime (Dp < 25 nm). Once formed, these (secondary) aerosols grew from nucleation (diameter Dp < 25 nm) to Aitken (25 ≤ Dp ≤ 100 nm) regime and beyond, to the accumulation size regimes (100 ≤ Dp ≤ 1000 nm), with varying growth rates (GR) for the different size regimes at both the locations. A more rapid growth ~ 50 nm h-1 was observed at Trivandrum, in contrast to Hanle where the growth rate ranged from 0.1 to 20 nm h-1 for the transformation from the nucleation to accumulation - a size regime that can potentially act as cloud condensation nuclei (CCN). The faster coagulation led to lifetimes of < 1 h for nucleation mode particles.

  14. Expert elicitation on ultrafine particles: likelihood of health effects and causal pathways

    Directory of Open Access Journals (Sweden)

    Brunekreef Bert

    2009-07-01

    Full Text Available Abstract Background Exposure to fine ambient particulate matter (PM has consistently been associated with increased morbidity and mortality. The relationship between exposure to ultrafine particles (UFP and health effects is less firmly established. If UFP cause health effects independently from coarser fractions, this could affect health impact assessment of air pollution, which would possibly lead to alternative policy options to be considered to reduce the disease burden of PM. Therefore, we organized an expert elicitation workshop to assess the evidence for a causal relationship between exposure to UFP and health endpoints. Methods An expert elicitation on the health effects of ambient ultrafine particle exposure was carried out, focusing on: 1 the likelihood of causal relationships with key health endpoints, and 2 the likelihood of potential causal pathways for cardiac events. Based on a systematic peer-nomination procedure, fourteen European experts (epidemiologists, toxicologists and clinicians were selected, of whom twelve attended. They were provided with a briefing book containing key literature. After a group discussion, individual expert judgments in the form of ratings of the likelihood of causal relationships and pathways were obtained using a confidence scheme adapted from the one used by the Intergovernmental Panel on Climate Change. Results The likelihood of an independent causal relationship between increased short-term UFP exposure and increased all-cause mortality, hospital admissions for cardiovascular and respiratory diseases, aggravation of asthma symptoms and lung function decrements was rated medium to high by most experts. The likelihood for long-term UFP exposure to be causally related to all cause mortality, cardiovascular and respiratory morbidity and lung cancer was rated slightly lower, mostly medium. The experts rated the likelihood of each of the six identified possible causal pathways separately. Out of these

  15. Using advanced dispersion models and mobile monitoring to characterize spatial patterns of ultrafine particles in an urban area

    Science.gov (United States)

    Zwack, Leonard M.; Hanna, Steven R.; Spengler, John D.; Levy, Jonathan I.

    2011-09-01

    In urban settings with elevated bridges, buildings, and other complex terrain, the relationship between traffic and air pollution can be highly variable and difficult to accurately characterize. Atmospheric dispersion models are often used in this context, but incorporating background concentrations and characterizing emissions at high spatiotemporal resolution is challenging, especially for ultrafine particles (UFPs). Ambient pollutant monitoring can characterize this relationship, especially when using continuous real-time monitoring. However, it is challenging to quantify local source contributions over background or to characterize spatial patterns across a neighborhood. The goal of this study is to evaluate contributions of traffic to neighborhood-scale air pollution using a combination of regression models derived from mobile UFP monitoring observations collected in Brooklyn, NY and outputs from the Quick Urban & Industrial Complex (QUIC) model. QUIC is a dispersion model that can explicitly take into account the three-dimensional shapes of buildings. The monitoring-based regression model characterized concentration gradients from a major elevated roadway, controlling for real-time traffic volume, meteorological variables, and other local sources. QUIC was applied to simulate dispersion from this same major roadway. The relative concentration decreases with distance from the roadway estimated by the monitoring-based regression model after removal of background and by QUIC were similar. Horizontal contour plots with both models demonstrated non-uniform patterns related to building configuration and source heights. We used the best-fit relationship between the monitoring-based regression model after removal of background and the QUIC outputs ( R2 = 0.80) to estimate a UFP emissions factor of 5.7 × 10 14 particles/vehicle-km, which was relatively consistent across key model assumptions. Our joint applications of novel techniques for analyzing mobile monitoring

  16. Preparation and Characterization of CeO2-ZrO2 Solid Solution Ultrafine Particles Using Reversed Microemulsion

    Institute of Scientific and Technical Information of China (English)

    An Yuan; Li Li; Wang Jun; Shen Meiqing

    2005-01-01

    Ce0.6Zr0.4O2 solid solution ultrafine particle was prepared in the cyclohexane/water/OP-10/n-hexanol reversed microemulsion. The quasi-ternary phase diagram investigations showed that the system has narrow W/O type microemulison region, so it is the proper system to prepare Ce0.6Zr0.4O2 solid solution ultrafine particle. Some physical-chemical techniques such as TG/DTA, XRD, BET, and HRTEM are used to characterize the resultant powders. The results show that the fluorite cubic Ce0.6Zr0.4O2 solid solution is obtained at 400 ℃. The surface area is (146.7 m2·g-1), which is higher than the surface area for sol-gel prepared sample (59.5 m2·g-1). HRTEM images indicated that the Ce0.6Zr0.4O2 solid solution ultrafine particle is well-crystallized, narrow size distribution, less agglomeration, within mean size of 5~7 nm.

  17. Transition metals in coarse, fine, very fine and ultra-fine particles from an interstate highway transect near Detroit

    Science.gov (United States)

    Cahill, Thomas A.; Barnes, David E.; Lawton, Jonathan A.; Miller, Roger; Spada, Nicholas; Willis, Robert D.; Kimbrough, Sue

    2016-11-01

    As one component of a study investigating the impact of vehicle emissions on near-road air quality, human exposures, and potential health effects, particles were measured from September 21 to October 30, 2010 on both sides of a major roadway (Interstate-96) in Detroit. Traffic moved freely on this 12 lane freeway with a mean velocity of 69 mi/hr. with little braking and acceleration. The UC Davis DELTA Group rotating drum (DRUM) impactors were used to collect particles in 8 size ranges at sites nominally 100 m south, 10 m north, 100 m north, and 300 m north of the highway. Ultra-fine particles were continuously collected at the 10 m north and 100 m north sites. Samples were analyzed every 3 h for mass (soft beta ray transmission), 42 elements (synchrotron-induced x-ray fluorescence) and optical attenuation (350-800 nm spectroscopy). A three day period of steady southerly winds along the array allowed direct measurement of freeway emission rates for coarse (10 > Dp > 1.0 μm), PM2.5, very fine (0.26 > Dp > 0.09 μm), and ultra-fine (Dp car and truck emission rates of 1973, this value would have been about 16 μg/m3, corrected down from the 19 μg/m3 PM5.0 using measured roadway dust contributions. This would have included 2.7 μg/m3 of lead, versus the 0.0033 μg/m3 measured. Very fine particles were distributed across the array with a relatively weak falloff versus distance. For the ultra-fine particles, emissions of soot and metals seen in vehicular braking studies correlated with traffic at the 10 m site, but only the soot was statistically significant at the 100 m north site. Otherwise, the 10 m north and 100 m north sites were essentially identical in mean concentration and highly correlated in time for most of the 5 week study. This result supports earlier publications showing the ability of very fine and ultra-fine particles to transport to sites well removed from the freeway sources. The concentrations of very fine and ultra-fine metals from brake wear and

  18. MEMS-based silicon cantilevers with integrated electrothermal heaters for airborne ultrafine particle sensing

    Science.gov (United States)

    Wasisto, Hutomo Suryo; Merzsch, Stephan; Waag, Andreas; Peiner, Erwin

    2013-05-01

    The development of low-cost and low-power MEMS-based cantilever sensors for possible application in hand-held airborne ultrafine particle monitors is described in this work. The proposed resonant sensors are realized by silicon bulk micromachining technology with electrothermal excitation, piezoresistive frequency readout, and electrostatic particle collection elements integrated and constructed in the same sensor fabrication process step of boron diffusion. Built-in heating resistor and full Wheatstone bridge are set close to the cantilever clamp end for effective excitation and sensing, respectively, of beam deflection. Meanwhile, the particle collection electrode is located at the cantilever free end. A 300 μm-thick, phosphorus-doped silicon bulk wafer is used instead of silicon-on-insulator (SOI) as the starting material for the sensors to reduce the fabrication costs. To etch and release the cantilevers from the substrate, inductively coupled plasma (ICP) cryogenic dry etching is utilized. By controlling the etching parameters (e.g., temperature, oxygen content, and duration), cantilever structures with thicknesses down to 10 - 20 μm are yielded. In the sensor characterization, the heating resistor is heated and generating thermal waves which induce thermal expansion and further cause mechanical bending strain in the out-of-plane direction. A resonant frequency of 114.08 +/- 0.04 kHz and a quality factor of 1302 +/- 267 are measured in air for a fabricated rectangular cantilever (500x100x13.5 μm3). Owing to its low power consumption of a few milliwatts, this electrothermal cantilever is suitable for replacing the current external piezoelectric stack actuator in the next generation of the miniaturized cantilever-based nanoparticle detector (CANTOR).

  19. Effect of particle-fiber friction coefficient on ultrafine aerosol particles clogging in nanofiber based filter

    Science.gov (United States)

    Sambaer, Wannes; Zatloukal, Martin; Kimmer, Dusan

    2013-04-01

    Realistic SEM image based 3D filter model considering transition/free molecular flow regime, Brownian diffusion, aerodynamic slip, particle-fiber and particle-particle interactions together with a novel Euclidian distance map based methodology for the pressure drop calculation has been utilized for a polyurethane nanofiber based filter prepared via electrospinning process in order to more deeply understand the effect of particle-fiber friction coefficient on filter clogging and basic filter characteristics. Based on the performed theoretical analysis, it has been revealed that the increase in the fiber-particle friction coefficient causes, firstly, more weaker particle penetration in the filter, creation of dense top layers and generation of higher pressure drop (surface filtration) in comparison with lower particle-fiber friction coefficient filter for which deeper particle penetration takes place (depth filtration), secondly, higher filtration efficiency, thirdly, higher quality factor and finally, higher quality factor sensitivity to the increased collected particle mass. Moreover, it has been revealed that even if the particle-fiber friction coefficient is different, the cake morphology is very similar.

  20. Modeling ultrafine particle growth at a pine forest site influenced by anthropogenic pollution during BEACHON-RoMBAS 2011

    Science.gov (United States)

    Cui, Y. Y.; Hodzic, A.; Smith, J. N.; Ortega, J.; Brioude, J.; Matsui, H.; Levin, E. J. T.; Turnipseed, A.; Winkler, P.; de Foy, B.

    2014-10-01

    Formation and growth of ultrafine particles is crudely represented in chemistry-climate models, contributing to uncertainties in aerosol composition, size distribution, and aerosol effects on cloud condensation nuclei (CCN) concentrations. Measurements of ultrafine particles, their precursor gases, and meteorological parameters were performed in a ponderosa pine forest in the Colorado Front Range in July-August 2011, and were analyzed to study processes leading to small particle burst events (PBEs) which were characterized by an increase in the number concentrations of ultrafine 4-30 nm diameter size particles. These measurements suggest that PBEs were associated with the arrival at the site of anthropogenic pollution plumes midday to early afternoon. During PBEs, number concentrations of 4-30 nm diameter particles typically exceeded 104 cm-3, and these elevated concentrations coincided with increased SO2 and monoterpene concentrations, and led to a factor-of-2 increase in CCN concentrations at 0.5% supersaturation. The PBEs were simulated using the regional WRF-Chem model, which was extended to account for ultrafine particle sizes starting at 1 nm in diameter, to include an empirical activation nucleation scheme in the planetary boundary layer, and to explicitly simulate the subsequent growth of Aitken particles (10-100 nm) by condensation of organic and inorganic vapors. The updated model reasonably captured measured aerosol number concentrations and size distribution during PBEs, as well as ground-level CCN concentrations. Model results suggest that sulfuric acid originating from anthropogenic SO2 triggered PBEs, and that the condensation of monoterpene oxidation products onto freshly nucleated particles contributes to their growth. The simulated growth rate of ~ 3.4 nm h-1 for 4-40 nm diameter particles was comparable to the measured average value of 2.3 nm h-1. Results also suggest that the presence of PBEs tends to modify the composition of sub-20 nm diameter

  1. Autophagy is essential for ultrafine particle-induced inflammation and mucus hyperproduction in airway epithelium.

    Science.gov (United States)

    Chen, Zhi-Hua; Wu, Yin-Fang; Wang, Ping-Li; Wu, Yan-Ping; Li, Zhou-Yang; Zhao, Yun; Zhou, Jie-Sen; Zhu, Chen; Cao, Chao; Mao, Yuan-Yuan; Xu, Feng; Wang, Bei-Bei; Cormier, Stephania A; Ying, Song-Min; Li, Wen; Shen, Hua-Hao

    2016-01-01

    Environmental ultrafine particulate matter (PM) is capable of inducing airway injury, while the detailed molecular mechanisms remain largely unclear. Here, we demonstrate pivotal roles of autophagy in regulation of inflammation and mucus hyperproduction induced by PM containing environmentally persistent free radicals in human bronchial epithelial (HBE) cells and in mouse airways. PM was endocytosed by HBE cells and simultaneously triggered autophagosomes, which then engulfed the invading particles to form amphisomes and subsequent autolysosomes. Genetic blockage of autophagy markedly reduced PM-induced expression of inflammatory cytokines, e.g. IL8 and IL6, and MUC5AC in HBE cells. Mice with impaired autophagy due to knockdown of autophagy-related gene Becn1 or Lc3b displayed significantly reduced airway inflammation and mucus hyperproduction in response to PM exposure in vivo. Interference of the autophagic flux by lysosomal inhibition resulted in accumulated autophagosomes/amphisomes, and intriguingly, this process significantly aggravated the IL8 production through NFKB1, and markedly attenuated MUC5AC expression via activator protein 1. These data indicate that autophagy is required for PM-induced airway epithelial injury, and that inhibition of autophagy exerts therapeutic benefits for PM-induced airway inflammation and mucus hyperproduction, although they are differentially orchestrated by the autophagic flux.

  2. Exposure to ultrafine particles and black carbon in diesel-powered commuter trains

    Science.gov (United States)

    Jeong, Cheol-Heon; Traub, Alison; Evans, Greg J.

    2017-04-01

    Ultrafine particle (UFP), black carbon (BC) and lung deposited surface area (LDSA) concentrations measured during 43 trips on diesel-powered commuter trains revealed elevated exposures under some conditions. When the passenger coaches were pulled by a locomotive, the geometric mean concentrations of UFP, LDSA, and BC were 18, 10, and 6 times higher than the exposure levels when the locomotive pushed the coaches, respectively. In addition, UFP, LDSA, and BC concentrations in pull-trains were 5, 3, and 4 times higher than concentrations measured while walking on city sidewalks, respectively. Exposure to these pollutants was most elevated in the coach located closest to the locomotive: geometric means were 126,000 # cm-3 for UFP, 249 μm2 cm-3 for LDSA, and 17,800 ng m-3 of BC; these concentrations are much higher than those previously reported for other modes of public transportation. Markedly high levels of diesel exhaust are present in passenger trains powered by diesel locomotives operated in pull-mode. Thus, it is recommended that immediate steps be taken to evaluate, and where needed, mitigate exposure in diesel-powered passenger trains, both commuter and inter-city.

  3. Field comparison of instruments for exposure assessment of airborne ultrafine particles and particulate matter

    Science.gov (United States)

    Spinazzè, Andrea; Fanti, Giacomo; Borghi, Francesca; Del Buono, Luca; Campagnolo, Davide; Rovelli, Sabrina; Cattaneo, Andrea; Cavallo, Domenico M.

    2017-04-01

    The objective of this study was to compare the use of co-located real-time devices and gravimetric samplers to measure ultrafine particles (UFP) and size-fractionated PM mass concentrations. The results contribute to evaluating the comparability of different monitoring instruments for size-fractionated PM concentrations. Paired light scattering devices and gravimetric samplers were used to measure the PM1, PM2.5, PM4/5, PM10 and TSP mass concentrations during 8-h monitoring sessions in an urban background site (Como, Italy) in winter. A total of 16 sampling sessions were performed: measurements were analyzed using linear regression analysis. Absolute deviations between techniques were calculated and discussed. The UFP concentrations measured using a condensation particle counter were clearly overestimated compared with the reference instrument (portable diffusion charger), with an absolute deviation that appeared to increase with the UFP concentration. The comparison of different light-scattering devices (photometers - 'PHOTs') indicated an over-estimation of two of the tested instruments (PHOT-2 and PHOT-3) with respect to the one used as the reference (PHOT-1) regarding the measurement of the size-fractioned PM, with the only exception being PM4/5. Further, the comparison of different light-scattering devices with filter-based samplers indicated that direct-reading devices tend to over-estimate (PHOT-2, PHOT-3) or under-estimate (PHOT-1) the PM concentrations from gravimetric analysis. The comparison of different filter-based samplers showed that the observed over-estimation error increased with increasing PM concentration levels; however, the good level of agreement between the investigated methods allowed them to be classified as comparable, although they cannot be characterized as having reciprocal predictability. Ambient relative humidity was correlated with the absolute error resulting from the comparison of direct-reading vs. filter-based techniques, as

  4. Empirical estimates of size-resolved precipitation scavenging coefficients for ultrafine particles

    Science.gov (United States)

    Pryor, S. C.; Joerger, V. M.; Sullivan, R. C.

    2016-10-01

    Below-cloud scavenging coefficients for ultrafine particles (UFP) exhibit comparatively large uncertainties in part because of the limited availability of observational data sets from which robust parameterizations can be derived or that can be used to evaluate output from numerical models. Long time series of measured near-surface UFP size distributions and precipitation intensity from the Midwestern USA are used here to explore uncertainties in scavenging coefficients and test both the generalizability of a previous empirical parameterization developed using similar data from a boreal forest in Finland (Laakso et al., 2003) and whether a more parsimonious formulation can be developed. Scavenging coefficients (λ) over an ensemble of 95 rain events (with a median intensity of 1.56 mm h-1) and 104 particle diameter (Dp) classes (from 10 to 400 nm) indicate a mean value of 3.4 × 10-5 s-1 (with a standard error of 1.1 × 10-6 s-1) and a median of 1.9 × 10-5 s-1 (interquartile range: -2.0 × 10-5 to 7.5 × 10-5 s-1). The median scavenging coefficients for Dp: 10-400 nm computed over all 95 rain events exhibit close agreement with the empirical parameterization proposed by (Laakso et al., 2003). They decline from ∼4.1 × 10-5 s-1 for Dp of 10-19 nm, to ∼1.6 × 10-5 s-1 for Dp of 80-113 nm, and show an increasing tendency for Dp > 200 nm.

  5. Long-term observations of tropospheric particle number size distributions and equivalent black carbon mass concentrations in the German Ultrafine Aerosol Network (GUAN

    Directory of Open Access Journals (Sweden)

    W. Birmili

    2015-11-01

    Full Text Available The German Ultrafine Aerosol Network (GUAN is a cooperative atmospheric observation network, which aims at improving the scientific understanding of aerosol-related effects in the troposphere. The network addresses research questions dedicated to both, climate and health related effects. GUAN's core activity has been the continuous collection of tropospheric particle number size distributions and black carbon mass concentrations at seventeen observation sites in Germany. These sites cover various environmental settings including urban traffic, urban background, rural background, and Alpine mountains. In association with partner projects, GUAN has implemented a high degree of harmonisation of instrumentation, operating procedures, and data evaluation procedures. The quality of the measurement data is assured by laboratory intercomparisons as well as on-site comparisons with reference instruments. This paper describes the measurement sites, instrumentation, quality assurance and data evaluation procedures in the network as well as the EBAS repository, where the data sets can be obtained (doi:10.5072/guan.

  6. Concentration levels and source apportionment of ultrafine particles in road microenvironments

    Science.gov (United States)

    Argyropoulos, G.; Samara, C.; Voutsa, D.; Kouras, A.; Manoli, E.; Voliotis, A.; Tsakis, A.; Chasapidis, L.; Konstandopoulos, A.; Eleftheriadis, K.

    2016-03-01

    A mobile laboratory unit (MOBILAB) with on-board instrumentation (Scanning Mobility Particle Sizer, SMPS; Ambient NOx analyzer) was used to measure size-resolved particle number concentrations (PNCs) of quasi-ultrafine particles (UFPs, 9-372 nm), along with NOx, in road microenvironments. On-road measurements were carried out in and around a large Greek urban agglomeration, the Thessaloniki Metropolitan Area (TMA). Two 2-week measurement campaigns were conducted during the warm period of 2011 and the cold period of 2012. During each sampling campaign, MOBILAB was driven through a 5-day inner-city route and a second 5-day external route covering in total a wide range of districts (urban, urban background, industrial and residential), and road types (major and minor urban roads, freeways, arterial and interurban roads). All routes were conducted during working days, in morning and in afternoon hours under real-world traffic conditions. Spatial classification of MOBILAB measurements involved the assignment of measurement points to location bins defined by the aspect ratio of adjacent urban street canyons (USCs). Source apportionment was further carried out, by applying Positive Matrix Factorization (PMF) to particle size distribution data. Apportioned PMF factors were interpreted, by employing a two-step methodology, which involved (a) statistical association of PMF factor contributions with 12 h air-mass back-trajectories ending at the TMA during MOBILAB measurements, and (b) Multiple Linear Regression (MLR) using PMF factor contributions as the dependent variables, while relative humidity, solar radiation flux, and vehicle speed were used as the independent variables. The applied data analysis showed that low-speed cruise and high-load engine operation modes are the two dominant sources of UFPs in most of the road microenvironments in the TMA, with significant contributions from background photochemical processes during the warm period, explaining the reversed

  7. Combustion derived ultrafine particles induce cytochrome P-450 expression in specific lung compartments in the developing neonatal and adult rat

    Science.gov (United States)

    Chan, Jackie K. W.; Vogel, Christoph F.; Baek, Jaeeun; Kodani, Sean D.; Uppal, Ravi S.; Bein, Keith J.; Anderson, Donald S.

    2013-01-01

    Vehicle exhaust is rich in polycyclic aromatic hydrocarbons (PAH) and can be a dominant contributor to ultrafine urban particulate matter (PM). Exposure to ultrafine PM is correlated with respiratory infections and asthmatic symptoms in young children. The lung undergoes substantial growth, alveolarization, and cellular maturation within the first years of life, which may be impacted by environmental pollutants such as PM. PAHs in PM can serve as ligands for the aryl hydrocarbon receptor (AhR) that induces expression of certain isozymes in the cytochrome P-450 superfamily, such as CYP1A1 and CYP1B1, localized in specific lung cell types. Although AhR activation and induction has been widely studied, its context within PM exposure and impact on the developing lung is poorly understood. In response, we have developed a replicable ultrafine premixed flame particle (PFP) generating system and used in vitro and in vivo models to define PM effects on AhR activation in the developing lung. We exposed 7-day neonatal and adult rats to a single 6-h PFP exposure and determined that PFPs cause significant parenchymal toxicity in neonates. PFPs contain weak AhR agonists that upregulate AhR-xenobiotic response element activity and expression and are capable inducers of CYP1A1 and CYP1B1 expression in both ages with different spatial and temporal patterns. Neonatal CYP1A1 expression was muted and delayed compared with adults, possibly because of differences in the enzyme maturation. We conclude that the inability of neonates to sufficiently adapt in response to PFP exposure may, in part, explain their susceptibility to PFP and urban ultrafine PM. PMID:23502512

  8. Observations of ultrafine particle nucleation events in the tropical UT/LS over West Africa and Brazil

    Science.gov (United States)

    Borrmann, S.; Curtius, J.; Kunkel, D.; Weigel, R.; Vicani, S.; Schiller, C.; Ulanovski, A.; Ravegnani, F.; Cairo, F.; Law, K. A.

    2009-04-01

    New particle formation by gas to particle conversion in the tropical upper troposphere and lower stratosphere (UT/LS) may be a major source of aerosols for origin and maintenance of the global stratospheric Junge aerosol layer. Once created in the tropical upper troposphere these ultrafine particles can be carried aloft towards the tropopause by the -radiatively driven- slowly rising air, and subsequently enter the Brewer-Dobson circulation for global distribution within the stratosphere. During the TROCCINOX (2005) and AMMA-SCOUT (2006) campaigns in South America (Brazil) and West-Africa (Burkina Faso) the Russian M-55 high altitude research aircraft "Geophysica" performed in-situ measurements of trace gases and aerosols in the tropical UT/LS. By means of the four channel COPAS condensation particle counting system total ultrafine particle number concentrations were measured for ambient aerosol particles with size diameters larger than 6 nm, 10 nm, and 14 nm, respectively. The fourth channel also had a lower "cut-off" diameter of 10 nm, but here the sample air was heated to 250 °C prior to the particle detection. Thus, this channel delivered the number of non volatile particles providing information on the fraction of particles NOT consisting of binary sulfuric acid/water solutions. During both campaigns cloud free air masses were encountered between 12 and 14 km altitude with ultrafine particle concentrations as high as 8000 to 10000 particles per cm³. Based on the difference of the count results from the channels with 6 nm and 14 nm cut-off diameters it can be concluded that the particles were freshly formed in-situ during so called nucleation events. Covering flight path lengths of roughly 300 km over West-Africa and 600 km over Brazil these areas with enhanced particle concentrations are of significant scale. For the data observed over Brazil oxidation of ground released SO2 to H2SO4 while being lifted -possibly supported by ion induced nucleation- is a

  9. 超细颗粒卤化银的制备与稳定性%PREPARATION OF ULTRA-FINE SILVER HALIDE PARTICLES AND THEIR STABILITY

    Institute of Scientific and Technical Information of China (English)

    崔兴品; 岳军

    1999-01-01

    With gelatin or gelatin+PVA as colloid protective medium and under proper reactive condition, ultra-fine silver iodobromide particles with average diameter of about 20 nm and better monodispersity were prepared by direct reaction of silver nitrate with mixture of potassium bromide and potassium iodide. According to TEM data, it was discovered that gelatin+PVA showed stronger colloid protective power for these ultra-fine particles, which restrained particles' coalescence and growth effectively during physical and chemical ripening, so that there was not observable change of particle size and monodispersity to be found. In the case of only gelatin as colloid protective medium to prepare ultra-fine silver iodobromide particles, particles'stability in the process of physical ripening depended on the ratio of gelatin amount to silver content as the preparing reaction. It appears that there exists a critical ratio of gelatin amount to silver content for particles′ stability. When experimental ratio of gelatin amount to silver content in the reaction was over this critical ratio, gelatin can protect ultra-fine particles against coalescence and growth to a considerable degree. On the contrary, the particle size beacme significantly large in the process of physical ripening due to decrease of gelatin protective power if the experimental ratio was lower than this critical ratio.

  10. Personal exposure of street canyon intersection users to PM 2.5, ultrafine particle counts and carbon monoxide in Central London, UK

    Science.gov (United States)

    Kaur, S.; Nieuwenhuijsen, M.; Colvile, R.

    Short-term human exposure to PM 2.5, ultrafine particle counts (particle range: 0.02-1 μm) and carbon monoxide (CO) was investigated at and around a street canyon intersection in Central London, UK. During a four-week field campaign, groups of four volunteers collected samples at three timings (morning, lunch and afternoon), along two different routes (a heavily trafficked route and a backstreet route) via five modes of transport (walking, cycling, bus, car and taxi). PM 2.5 was sampled using high-flow gravimetric personal samplers, ultrafine particle counts were measured using TSI P-TRAKs and Langans were used to measure CO exposure. Three hundred and ninety-four samples were collected—197 PM 2.5, 86 ultrafine particle count and 111 CO. Arithmetic means of PM 2.5 personal exposure were 27.5, 33.5, 34.5, 38.0 and 41.5 μg m -3, ultrafine particle counts were 67 773, 93 968, 101 364, 99 736 and 87 545 pt cm -3 and CO levels were 0.9, 1.1, 0.8, 1.3 and 1.1 ppm for walking, cycling, bus, car and taxi respectively. On the heavily trafficked route, personal exposure was 35.3 μg m -3, 101142 pt cm -3 and 1.3 ppm, and on the backstreet route it was 31.8 μg m -3, 71628 pt cm -3 and 0.6 ppm for PM 2.5, ultrafine particle counts and CO, respectively. Personal exposure levels were high during the morning measurements for all three pollutants (34.6 μg m -3, 106 270 pt cm -3 and 1.5 ppm for PM 2.5, ultrafine particle counts and CO, respectively).There was a moderately strong correlation between personal exposure of ultrafine particle counts and CO ( r=0.7, N=67) but a weaker correlation between PM 2.5 and ultrafine particle counts ( r=0.5, N=83) and a low correlation between PM 2.5 and CO exposure ( r=0.2, N=105). The exposure assessment also revealed that the background and kerbside monitoring stations were not representative of the personal exposure of individuals to PM 2.5 and CO at and around a street canyon intersection.

  11. Hygroscopic properties of newly formed ultrafine particles at an urban site surrounded by deciduous forest (Sapporo, northern Japan) during the summer of 2011

    Science.gov (United States)

    Jung, J.; Kawamura, K.

    2014-07-01

    To investigate the hygroscopic properties of ultrafine particles during new particle formation events, the hygroscopic growth factors of size-segregated atmospheric particles were measured at an urban site in Sapporo, northern Japan, during the summer of 2011. The hygroscopic growth factor at 85 % relative humidity [g(85%)] of freshly formed nucleation mode particles was 1.11 to 1.28 (average: 1.16 ± 0.06) at a dry particle diameter (Dp) centered on 20 nm, which is equivalent to 1.17 to 1.35 (1.23 ± 0.06) at a dry Dp centered on 100 nm after considering the Kelvin effect. These values are comparable with those of secondary organic aerosols, suggesting that low-volatility organic vapors are important to the burst of nucleation mode particles. The equivalent g(85%) at a dry Dp of 100 nm for nucleated particles that have grown to Aitken mode sizes (1.24 to 1.34; average: 1.30 ± 0.04) were slightly higher than those of newly formed nucleation mode particles, suggesting that the growth of freshly formed nucleation mode particles to the Aitken mode size can be subjected to condensation of not only low-volatility organic vapors, but also water-soluble inorganic species. Based on this result, and previous measurement of radiocarbon in aerosols, we suggest that the burst of nucleation mode particles and their subsequent growth were highly affected by biogenic organic emissions at this measurement site, which is surrounded by deciduous forest. Gradual increases in mode diameter after the burst of nucleation mode particles were observed under southerly wind conditions, with a dominant contribution of intermediately hygroscopic particles. However, sharp increases in mode diameter were observed when the wind direction shifted to northwesterly or northeasterly, with a sharp increase in the highly hygroscopic particle fraction of the Aitken mode particles, indicating that the hygroscopic growth factor of newly formed particles is perturbed by the local winds that deliver

  12. Effect of Ultrafine particles on Flow Field and Transport Properties near the nterface Around a Moving Bubble

    Institute of Scientific and Technical Information of China (English)

    马友光; 徐世昌; 冯惠生

    2004-01-01

    Laser Doppler Anemometer has been used to measure the flow field characteristics near the interface around a moving bubble in the presence of ultrafine particles. In order to model a moving bubble, the bubble was fixed into the counter-flow liquid by a metal mesh. Experimental materials are air and water, and the particles are complex oxidate powder. Experiments were carried out under the operating conditions: the liquid flow velocity u0 is 12.6 cm/s, the equivalent diameter de is 0.6 cm, the mass concentration of particle is 0.2%,the average particle diameter is about 10 nm and the density is 2 g/cm3. The velocity profiles of both frontal and tail-vortex areas were measured respectively. The experimental results show that the velocity fields are obviously changed in the existence of particles. In the frontal area of the bubble, both tangential and normal velocities decrease due to the presence of particles, but in tail vortex area, the tangential velocities increase remarkably, and normal velocities rise gradually from the center towards the fringe in the opposite tendency to that of no particles. The influences of flow field change in the presence of particles on gas-liquid mass transfer are analyzed and discussed.

  13. Ultrafine particles from electric appliances and cooking pans: experiments suggesting desorption/nucleation of sorbed organics as the primary source.

    Science.gov (United States)

    Wallace, L A; Ott, W R; Weschler, C J

    2015-10-01

    Ultrafine particles are observed when metal surfaces, such as heating elements in electric appliances, or even empty cooking pans, are heated. The source of the particles has not been identified. We present evidence that particles >10 nm are not emitted directly from the heating elements or the metal surfaces. Using repeated heating of an electric burner, several types of cooking pans, and a steam iron, the increase in the number of particles (>10 nm) can be reduced to 0. After the devices are exposed to indoor air for several hours or days, subsequent heating results in renewed particle production, suggesting that organic matter has sorbed on their surfaces. Also, after a pan has been heated to the point that no increase in particles is observed, washing with detergent results in copious production of particles the next time the pan is heated. These observations suggest that detergent residue and organics sorbed from indoor air are the sources of the particles. We hypothesize that organic compounds are thermally desorbed from the hot surface as gaseous molecules; as they diffuse from the hot air near the pan into cooler air, selected compounds exceed their saturation concentration and nucleation occurs.

  14. Redox Dynamics of Mixed Metal (Mn, Cr, and Fe) Ultrafine Particles

    Energy Technology Data Exchange (ETDEWEB)

    Nico, Peter S.; Kumfer, Benjamin M.; Kennedy, Ian M.; Anastasio, Cort

    2008-08-01

    The impact of particle composition on metal oxidation state, and on changes in oxidation state with simulated atmospheric aging, are investigated experimentally in flame-generated nanoparticles containing Mn, Cr, and Fe. The results demonstrate that the initial fraction of Cr(VI) within the particles decreases with increasing total metal concentration in the flame. In contrast, the initial Mn oxidation state was only partly controlled by metal loading, suggesting the importance of other factors. Two reaction pathways, one reductive and one oxidative, were found to be operating simultaneously during simulated atmospheric aging. The oxidative pathway depended upon the presence of simulated sunlight and O{sub 3}, whereas the reductive pathway occurred in the presence of simulated sunlight alone. The reductive pathway appears to be rapid but transient, allowing the oxidative pathway to dominate with longer aging times, i.e. greater than {approx}8 hours. The presence of Mn within the particles enhanced the importance of the oxidative pathway, leading to more net Cr oxidation during aging implying that Mn can mediate oxidation by removal of electrons from other particulate metals.

  15. Response of spontaneously hypertensive rats to inhalation of fine and ultrafine particles from traffic: experimental controlled study

    Directory of Open Access Journals (Sweden)

    Dormans Jan AMA

    2006-05-01

    Full Text Available Abstract Background Many epidemiological studies have shown that mass concentrations of ambient particulate matter (PM are associated with adverse health effects in the human population. Since PM is still a very crude measure, this experimental study has explored the role of two distinct size fractions: ultrafine (3 to 3613 μg/m3 for fCAP and from 269μg/m3 to 556 μg/m3 for u+fCAP. Results Ammonium, nitrate, and sulphate ions accounted for 56 ± 16% of the total fCAP mass concentrations, but only 17 ± 6% of the u+fCAP mass concentrations. Unambiguous particle uptake in alveolar macrophages was only seen after u+fCAP exposures. Neither fCAP nor u+fCAP induced significant changes of cytotoxicity or inflammation in the lung. However, markers of oxidative stress (heme oxygenase-1 and malondialdehyde were affected by both fCAP and u+fCAP exposure, although not always significantly. Additional analysis revealed heme oxygenase-1 (HO-1 levels that followed a nonmonotonic function with an optimum at around 600 μg/m3 for fCAP. As a systemic response, exposure to u+fCAP and fCAP resulted in significant decreases of the white blood cell concentrations. Conclusion Minor pulmonary and systemic effects are observed after both fine and ultrafine + fine PM exposure. These effects do not linearly correlate with the CAP mass. A greater component of traffic CAP and/or a larger proportion ultrafine PM does not strengthen the absolute effects.

  16. Internal Combustion Engines as the Main Source of Ultrafine Particles in Residential Neighborhoods: Field Measurements in the Czech Republic

    Directory of Open Access Journals (Sweden)

    Jitka Stolcpartova

    2015-11-01

    Full Text Available Ultrafine particles (UFP, diameter < 100 nm exposure has already been associated with adverse effects on human health. Spatial distribution of UFP is non-uniform; they concentrate in the vicinity of the source, e.g. traffic, because of their short lifespan. This work investigates spatial distribution of UFP in three areas in the Czech Republic with different traffic load: High traffic (Prague neighborhood—Sporilov, commuter road vicinity (Libeznice, and a small city with only local traffic (Celakovice. Size-resolved measurements of particles in the 5–500 nm range were taken with a particle classifier mounted, along with batteries, GPS and other accessories, on a handcart and pushed around the areas, making one-minute or longer stops at places of interest. Concentrations along main roads were elevated in comparison with places farther from the road; this pattern was observed in all sites, while particle number distributions both close and away from main roads had similar patterns. The absence of larger particles, the relative absence of higher concentrations of particles away from the main roads, and similar number distributions suggest that high particle number concentrations cannot be readily attributed to sources other than internal combustion engines in vehicles and mobile machinery (i.e., mowers and construction machines.

  17. Aircraft observations of ultrafine particles and CCN from the boundary layer to the free troposphere in the Arctic summertime

    Science.gov (United States)

    Burkart, Julia; Willis, Megan; Bozem, Heiko; Hoor, Peter; Köllner, Franziska; Schneider, Johannes; Brauner, Ralf; Konrad, Christian; Herber, Andreas; Leaitch, Richard; Abbatt, Jon

    2016-04-01

    The Arctic is one of the regions most sensitive to climate change. The shrinking extent of sea ice during the Arctic summertime increases the area covered by open ocean, which likely impacts Arctic aerosol, cloud properties, and thus climate. In this context extensive aerosol measurements (aerosol composition, particle number and size, cloud condensation nuclei, and trace gases) have been made during the NETCARE 2014 summer campaign from the Polar 6 aircraft. The Polar 6 is an adopted DC-3 aircraft owned by the Alfred Wegener Institute in Bremerhaven, Germany. In July 2014 eleven flights were conducted out of Resolute Bay. Flights included vertical profiles from as low as 60 m up to 3 km, as well as several low-level flights covering diverse terrains such as open ocean, fast ice, melt ponds, and polynyas. Here we discuss the vertical distribution of ultrafine particles (UFP, dp: 5 - 20 nm), size distributions of larger particles (dp: 20 nm to 1 μm), and cloud condensation nuclei (CCN) in relation to different meteorological conditions and terrains. UFPs have been observed predominantly within the boundary layer, where concentrations reached several hundreds and occasionally even a few thousand particles per cubic centimeter. Highest concentrations were observed above open ocean and at the top of low-level clouds. During such events, the dominant mode of the size distribution was below 20 nm. However, in a few cases this ultrafine mode extended to sizes larger than 40 nm, suggesting that these UFP can grow into the CCN size range and thereby impact cloud properties and become climatically relevant.

  18. The chemical composition of ultrafine particles and associated biological effects at an alpine town impacted by wood burning.

    Science.gov (United States)

    Corsini, Emanuela; Vecchi, Roberta; Marabini, Laura; Fermo, Paola; Becagli, Silvia; Bernardoni, Vera; Caruso, Donatella; Corbella, Lorenza; Dell'Acqua, Manuela; Galli, Corrado L; Lonati, Giovanni; Ozgen, Senem; Papale, Angela; Signorini, Stefano; Tardivo, Ruggero; Valli, Gianluigi; Marinovich, Marina

    2017-02-25

    This work is part of the TOBICUP (TOxicity of BIomass Combustion generated Ultrafine Particles) project which aimed at providing the composition of ultrafine particles (UFPs, i.e. particles with aerodynamic diameter, dae, lower than 100nm) emitted by wood combustion and elucidating the related toxicity. Results here reported are from two ambient monitoring campaigns carried out at an alpine town in Northern Italy, where wood burning is largely diffused for domestic heating in winter. Wintertime and summertime UFP samples were analyzed to assess their chemical composition (i.e. elements, ions, total carbon, anhydrosugars, and polycyclic aromatic hydrocarbons) and biological activity. The induction of the pro-inflammatory cytokine interleukin-8 (IL-8) by UFPs was investigated in two human cells lines (A549 and THP-1) and in human peripheral blood leukocytes. In addition, UFP-induced oxidative stress and genotoxicity were investigated in A549 cells. Ambient UFP-related effects were compared to those induced by traffic-emitted particles (DEP) taken from the NIES reference material "vehicle exhaust particulates". Ambient air UFPs induced a dose-related IL-8 release in both A549 and THP-1 cells; the effect was more relevant on summer samples and in general THP-1 cells were more sensitive than A549 cells. On a weight basis our data did not support a higher biological activity of ambient UFPs compared to DEP. The production of IL-8 in the whole blood assay indicated that UFPs reached systemic circulation and activated blood leukocytes. Comet assay and γ-H2AX evaluation showed a significant DNA damage especially in winter UFPs samples compared to control samples. Our study showed that ambient UFPs can evoke a pulmonary inflammatory response by inducing a dose-related IL-8 production and DNA damage, with different responses to UFP samples collected in the summer and winter periods.

  19. Synthesis of Supported Ultrafine Non-noble Subnanometer-Scale Metal Particles Derived from Metal-Organic Frameworks as Highly Efficient Heterogeneous Catalysts.

    Science.gov (United States)

    Kang, Xinchen; Liu, Huizhen; Hou, Minqiang; Sun, Xiaofu; Han, Hongling; Jiang, Tao; Zhang, Zhaofu; Han, Buxing

    2016-01-18

    The properties of supported non-noble metal particles with a size of less than 1 nm are unknown because their synthesis is a challenge. A strategy has now been created to immobilize ultrafine non-noble metal particles on supports using metal-organic frameworks (MOFs) as metal precursors. Ni/SiO2 and Co/SiO2 catalysts were synthesized with an average metal particle size of 0.9 nm. The metal nanoparticles were immobilized uniformly on the support with a metal loading of about 20 wt%. Interestingly, the ultrafine non-noble metal particles exhibited very high activity for liquid-phase hydrogenation of benzene to cyclohexane even at 80 °C, while Ni/SiO2 with larger Ni particles fabricated by a conventional method was not active under the same conditions.

  20. Vapor scavenging by atmospheric aerosol particles

    Energy Technology Data Exchange (ETDEWEB)

    Andrews, E.

    1996-05-01

    Particle growth due to vapor scavenging was studied using both experimental and computational techniques. Vapor scavenging by particles is an important physical process in the atmosphere because it can result in changes to particle properties (e.g., size, shape, composition, and activity) and, thus, influence atmospheric phenomena in which particles play a role, such as cloud formation and long range transport. The influence of organic vapor on the evolution of a particle mass size distribution was investigated using a modified version of MAEROS (a multicomponent aerosol dynamics code). The modeling study attempted to identify the sources of organic aerosol observed by Novakov and Penner (1993) in a field study in Puerto Rico. Experimentally, vapor scavenging and particle growth were investigated using two techniques. The influence of the presence of organic vapor on the particle`s hydroscopicity was investigated using an electrodynamic balance. The charge on a particle was investigated theoretically and experimentally. A prototype apparatus--the refractive index thermal diffusion chamber (RITDC)--was developed to study multiple particles in the same environment at the same time.

  1. Sources and transformations of atmospheric aerosol particles

    Science.gov (United States)

    Cross, Eben Spencer

    Aerosol particles are an important component of the Earth-Atmosphere system because of their influence on the radiation budget both directly (through absorption and scattering) and indirectly (through cloud condensation nuclei (CCN) activity). The magnitude of the raditaive forcing attributed to the direct and indirect aerosol effects is highly uncertain, leading to large uncertainties in projections of global climate change. Real-time measurements of aerosol properties are a critical step toward constraining the uncertainties in current global climate modeling and understanding the influence that anthropogenic activities have on the climate. The objective of the work presented in this thesis is to gain a more complete understanding of the atmospheric transformations of aerosol particles and how such transformations influence the direct and indirect radiative effects of the particles. The work focuses on real-time measurements of aerosol particles made with the Aerodyne Aerosol Mass Spectrometer (AMS) developed in collaboration with the Boston College research group. A key feature of the work described is the development of a light scattering module for the AMS. Here we present the first results obtained with the integrated light scattering - AMS system. The unique and powerful capabilities of this new instrument combination are demonstrated through laboratory experiments and field deployments. Results from two field studies are presented: (1) The Northeast Air Quality Study (NEAQS), in the summer of 2004, conducted at Chebogue Point, Nova Scotia and (2) The Megacity Initiative: Local and Global Research Observations (MILAGRO) field campaign conducted in and around Mexico City, Mexico in March of 2006. Both field studies were designed to study the transformations that occur within pollution plumes as they are transported throughout the atmosphere. During the NEAQS campaign, the pollution plume from the Northeastern United States was intercepted as it was

  2. International Airport Impacts to Air Quality: Size and Related Properties of Large Increases in Ultrafine Particle Number Concentrations.

    Science.gov (United States)

    Hudda, N; Fruin, S A

    2016-04-05

    We measured particle size distributions and spatial patterns of particle number (PN) and particle surface area concentrations downwind from the Los Angeles International Airport (LAX) where large increases (over local background) in PN concentrations routinely extended 18 km downwind. These elevations were mostly comprised of ultrafine particles smaller than 40 nm. For a given downwind distance, the greatest increases in PN concentrations, along with the smallest mean sizes, were detected at locations under the landing jet trajectories. The smaller size of particles in the impacted area, as compared to the ambient urban aerosol, increased calculated lung deposition fractions to 0.7-0.8 from 0.5-0.7. A diffusion charging instrument (DiSCMini), that simulates alveolar lung deposition, measured a fivefold increase in alveolar-lung deposited surface area concentrations 2-3 km downwind from the airport (over local background), decreasing steadily to a twofold increase 18 km downwind. These ratios (elevated lung-deposited surface area over background) were lower than the corresponding ratios for elevated PN concentrations, which decreased from tenfold to twofold over the same distance, but the spatial patterns of elevated concentrations were similar. It appears that PN concentration can serve as a nonlinear proxy for lung deposited surface area downwind of major airports.

  3. A comparison of strategies for estimation of ultrafine particle number concentrations in urban air pollution monitoring networks.

    Science.gov (United States)

    Reggente, Matteo; Peters, Jan; Theunis, Jan; Van Poppel, Martine; Rademaker, Michael; De Baets, Bernard; Kumar, Prashant

    2015-04-01

    We propose three estimation strategies (local, remote and mixed) for ultrafine particles (UFP) at three sites in an urban air pollution monitoring network. Estimates are obtained through Gaussian process regression based on concentrations of gaseous pollutants (NOx, O3, CO) and UFP. As local strategy, we use local measurements of gaseous pollutants (local covariates) to estimate UFP at the same site. As remote strategy, we use measurements of gaseous pollutants and UFP from two independent sites (remote covariates) to estimate UFP at a third site. As mixed strategy, we use local and remote covariates to estimate UFP. The results suggest: UFP can be estimated with good accuracy based on NOx measurements at the same location; it is possible to estimate UFP at one location based on measurements of NOx or UFP at two remote locations; the addition of remote UFP to local NOx, O3 or CO measurements improves models' performance.

  4. Alternative pathway for atmospheric particles growth.

    Science.gov (United States)

    Monge, Maria Eugenia; Rosenørn, Thomas; Favez, Olivier; Müller, Markus; Adler, Gabriela; Abo Riziq, Ali; Rudich, Yinon; Herrmann, Hartmut; George, Christian; D'Anna, Barbara

    2012-05-01

    Credible climate change predictions require reliable fundamental scientific knowledge of the underlying processes. Despite extensive observational data accumulated to date, atmospheric aerosols still pose key uncertainties in the understanding of Earth's radiative balance due to direct interaction with radiation and because they modify clouds' properties. Specifically, major gaps exist in the understanding of the physicochemical pathways that lead to aerosol growth in the atmosphere and to changes in their properties while in the atmosphere. Traditionally, the driving forces for particle growth are attributed to condensation of low vapor pressure species following atmospheric oxidation of volatile compounds by gaseous oxidants. The current study presents experimental evidence of an unaccounted-for new photoinduced pathway for particle growth. We show that heterogeneous reactions activated by light can lead to fast uptake of noncondensable Volatile Organic Compounds (VOCs) at the surface of particles when only traces of a photosensitizer are present in the seed aerosol. Under such conditions, size and mass increase; changes in the chemical composition of the aerosol are also observed upon exposure to volatile organic compounds such as terpenes and near-UV irradiation. Experimentally determined growth rate values match field observations, suggesting that this photochemical process can provide a new, unaccounted-for pathway for atmospheric particle growth and should be considered by models.

  5. Ultrafine particles in four European urban environments: Results from a new continuous long-term monitoring network

    Science.gov (United States)

    Hofman, J.; Staelens, J.; Cordell, R.; Stroobants, C.; Zikova, N.; Hama, S. M. L.; Wyche, K. P.; Kos, G. P. A.; Van Der Zee, S.; Smallbone, K. L.; Weijers, E. P.; Monks, P. S.; Roekens, E.

    2016-07-01

    To gain a better understanding on the spatiotemporal variation of ultrafine particles (UFPs) in urban environments, this study reports on the first results of a long-term UFP monitoring network, set up in Amsterdam (NL), Antwerp (BE), Leicester (UK) and London (UK). Total number concentrations and size distributions were assessed during 1-2 years at four fixed urban background sites, supplemented with mobile trailer measurements for co-location monitoring and additional short-term monitoring sites. Intra- and interurban spatiotemporal UFP variation, associations with commonly-monitored pollutants (PM, NOx and BC) and impacts of wind fields were evaluated. Although comparable size distributions were observed between the four cities, source-related differences were demonstrated within specific particle size classes. Total and size-resolved particle number concentrations showed clear traffic-related temporal variation, confirming road traffic as the major UFP contributor in urban environments. New particle formation events were observed in all cities. Correlations with typical traffic-related pollutants (BC and NOx) were obtained for all monitoring stations, except for Amsterdam, which might be attributable to UFP emissions from Schiphol airport. The temporal variation in particle number concentration correlated fairly weakly between the four cities (rs = 0.28-0.50, COD = 0.28-0.37), yet improved significantly inside individual cities (rs = 0.59-0.77). Nevertheless, considerable differences were still obtained in terms of particle numbers (20-38% for total particle numbers and up to 49% for size-resolved particle numbers), confirming the importance of local source contributions and the need for careful consideration when allocating UFP monitoring stations in heterogeneous urban environments.

  6. Measured performance of filtration and ventilation systems for fine and ultrafine particles and ozone in an unoccupied modern California house.

    Science.gov (United States)

    Singer, B C; Delp, W W; Black, D R; Walker, I S

    2016-12-05

    This study evaluated nine ventilation and filtration systems in an unoccupied 2006 house located 250 m downwind of the I-80 freeway in Sacramento, California. Systems were evaluated for reducing indoor concentrations of outdoor particles in summer and fall/winter, ozone in summer, and particles from stir-fry cooking. Air exchange rate was measured continuously. Energy use was estimated for year-round operation in California. Exhaust ventilation without enhanced filtration provided indoor PM2.5 that was 70% lower than outdoors. Supply ventilation with MERV13 filtration provided slightly less protection, whereas supply MERV16 filtration reduced PM2.5 by 97-98% relative to outdoors. Supply filtration systems used little energy but provided no benefits for indoor-generated particles. Systems with MERV13-16 filter in the recirculating heating and cooling unit (FAU) operating continuously or 20 min/h reduced PM2.5 by 93-98%. Across all systems, removal percentages were higher for ultrafine particles and lower for black carbon, relative to PM2.5 . Indoor ozone was 3-4% of outdoors for all systems except an electronic air cleaner that produced ozone. Filtration via the FAU or portable filtration units lowered PM2.5 by 25-75% when operated over the hour following cooking. The energy for year-round operation of FAU filtration with an efficient blower motor was estimated at 600 kWh/year.

  7. Effect of cabin ventilation rate on ultrafine particle exposure inside automobiles.

    Science.gov (United States)

    Knibbs, Luke D; de Dear, Richard J; Morawska, Lidia

    2010-05-01

    We alternately measured on-road and in-vehicle ultrafine (automobiles and ventilation settings, a positive linear relationship was found between outdoor air flow rate and I/O ratio, with the former accounting for a substantial proportion of variation in the latter (R(2) = 0.81). UFP concentrations recorded in-cabin during tunnel travel were significantly higher than those reported by comparable studies performed on open roadways. A simple mathematical model afforded the ability to predict tunnel trip average in-cabin UFP concentrations with good accuracy. Our data indicate that under certain conditions, in-cabin UFP exposures incurred during tunnel travel may contribute significantly to daily exposure. The UFP exposure of automobile occupants appears strongly related to their choice of ventilation setting and vehicle.

  8. Analysis of the chemical composition of ultrafine particles from two domestic solid biomass fired room heaters under simulated real-world use

    Science.gov (United States)

    Ozgen, Senem; Becagli, Silvia; Bernardoni, Vera; Caserini, Stefano; Caruso, Donatella; Corbella, Lorenza; Dell'Acqua, Manuela; Fermo, Paola; Gonzalez, Raquel; Lonati, Giovanni; Signorini, Stefano; Tardivo, Ruggero; Tosi, Elisa; Valli, Gianluigi; Vecchi, Roberta; Marinovich, Marina

    2017-02-01

    Two common types of wood (beech and fir) were burned in commercial pellet (11.1 kW) and wood (8.2 kW) stoves following a combustion cycle simulating the behavior of a real-world user. Ultrafine particulate matter (UFP, dp carbon, and PAH content. The measurement of the number concentration and size distribution was also performed by a fourth multistage impactor. UFP mass emission factors averaged to 424 mg/kgfuel for all the tested stove and wood type (fir, beech) combinations except for beech log burning in the wood stove (838 mg/kgfuel). Compositional differences were observed for pellets and wood UFP samples, where high TC levels characterize the wood log combustion and potassium salts are dominant in every pellet sample. Crucial aspects determining the UFP composition in the wood stove experiments are critical situations in terms of available oxygen (a lack or an excess of combustion air) and high temperatures. Whereas for the automatically controlled pellets stove local situations (e.g., hindered air-fuel mixing due to heaps of pellets on the burner pot) determine the emission levels and composition. Wood samples contain more potentially carcinogenic PAHs with respect to pellets samples. Some diagnostic ratios related to PAH isomers and anhydrosugars compiled from experimental UFP data in the present study and compared to literature values proposed for the emission source discrimination for atmospheric aerosol, extend the evaluation usually limited to higher particle size fractions also to UFP.

  9. Contribution of various microenvironments to the daily personal exposure to ultrafine particles: Personal monitoring coupled with GPS tracking

    Science.gov (United States)

    Bekö, Gabriel; Kjeldsen, Birthe Uldahl; Olsen, Yulia; Schipperijn, Jasper; Wierzbicka, Aneta; Karottki, Dorina Gabriela; Toftum, Jørn; Loft, Steffen; Clausen, Geo

    2015-06-01

    Exposure to ultrafine particles (UFP) may have adverse health effects. Central monitoring stations do not represent the personal exposure to UFP accurately. Few studies have previously focused on personal exposure to UFP. Sixty non-smoking residents living in Copenhagen, Denmark were asked to carry a backpack equipped with a portable monitor, continuously recording particle number concentrations (PN), in order to measure the real-time individual exposure over a period of ˜48 h. A GPS logger was carried along with the particle monitor and allowed us to estimate the contribution of UFP exposure occurring in various microenvironments (residence, during active and passive transport, other indoor and outdoor environments) to the total daily exposure. On average, the fractional contribution of each microenvironment to the daily integrated personal exposure roughly corresponded to the fractions of the day the subjects spent in each microenvironment. The home environment accounted for 50% of the daily personal exposure. Indoor environments other than home or vehicles contributed with ˜40%. The highest median UFP concentration was obtained during passive transport (vehicles). However, being in transit or outdoors contributed 5% or less to the daily exposure. Additionally, the subjects recorded in a diary the periods when they were at home. With this approach, 66% of the total daily exposure was attributable to the home environment. The subjects spent 28% more time at home according to the diary, compared to the GPS. These results may indicate limitations of using diaries, but also possible inaccuracy and miss-classification in the GPS data.

  10. Special Issue for the 9th International Conference on Carbonaceous Particles in the Atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Strawa, A.W.; Kirchstetter, T.W.; Puxbaum, H.

    2009-12-11

    Carbonaceous particles are a minor constituent of the atmosphere but have a profound effect on air quality, human health, visibility and climate. The importance of carbonaceous particles has been increasingly recognized and become a mainstream topic at numerous conferences. Such was not the case in 1978, when the 1st International Conference on Carbonaceous Particles in the Atmosphere (ICCPA), or ''Carbon Conference'' as it is widely known, was introduced as a new forum to bring together scientists who were just beginning to reveal the importance and complexity of carbonaceous particles in the environment. Table 1 lists the conference dates, venues in the series as well as the proceedings, and special issues resulting form the meetings. Penner and Novakov (Penner and Novakov, 1996) provide an excellent historical perspective to the early ICCPA Conferences. Thirty years later, the ninth in this conference series was held at its inception site, Berkeley, California, attended by 160 scientists from 31 countries, and featuring both new and old themes in 49 oral and 83 poster presentations. Topics covered such areas as historical trends in black carbon aerosol, ambient concentrations, analytic techniques, secondary aerosol formation, biogenic, biomass, and HULIS1 characterization, optical properties, and regional and global climate effects. The conference website, http://iccpa.lbl.gov/, holds the agenda, as well as many presentations, for the 9th ICCPA. The 10th ICCPA is tentatively scheduled for 2011 in Vienna, Austria. The papers in this issue are representative of several of the themes discussed in the conference. Ban-Weiss et al., (Ban-Weiss et al., accepted) measured the abundance of ultrafine particles in a traffic tunnel and found that heavy duty diesel trucks emit at least an order of magnitude more ultrafine particles than light duty gas-powered vehicles per unit of fuel burned. Understanding of this issue is important as ultrafine particles

  11. Association between short-term exposure to ultrafine particles and mortality in eight European urban areas

    DEFF Research Database (Denmark)

    Stafoggia, Massimo; Schneider, Alexandra; Cyrys, Josef;

    2017-01-01

    and non-accidental mortality, with mortality increasing by approximately 0.35% per 10,000 particles/cm increases in particle number concentration occurring 5 to 7 days before death. A similar pattern was found for cause-specific mortality. Estimates decreased after adjustment for fine particles (PM2...

  12. Control on Crystal Forms of Ultrafine Barium Carbonate Particles and Study on its Mechanism

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Barium carbonate particles were prepared by using homogeneous precipitation method and co-precipitation method respectively. Through adding different crystalline controlling modifiers, Barium carbonate particles in five different shapes including linear, needle-like, pillarlike, sphere-like and dumbbell-like were synthesized. These particles were characterized by SEM and XRD, and their synthetic mechanism was discussed in this paper.

  13. Maskless localized patterning of biomolecules on carbon nanotube microarray functionalized by ultrafine atmospheric pressure plasma jet using biotin-avidin system

    Science.gov (United States)

    Abuzairi, Tomy; Okada, Mitsuru; Purnamaningsih, Retno Wigajatri; Poespawati, Nji Raden; Iwata, Futoshi; Nagatsu, Masaaki

    2016-07-01

    Ultrafine plasma jet is a promising technology with great potential for nano- or micro-scale surface modification. In this letter, we demonstrated the use of ultrafine atmospheric pressure plasma jet (APPJ) for patterning bio-immobilization on vertically aligned carbon nanotube (CNT) microarray platform without a physical mask. The biotin-avidin system was utilized to demonstrate localized biomolecule patterning on the biosensor devices. Using ±7.5 kV square-wave pulses, the optimum condition of plasma jet with He/NH3 gas mixture and 2.5 s treatment period has been obtained to functionalize CNTs. The functionalized CNTs were covalently linked to biotin, bovine serum albumin (BSA), and avidin-(fluorescein isothiocyanate) FITC, sequentially. BSA was necessary as a blocking agent to protect the untreated CNTs from avidin adsorption. The localized patterning results have been evaluated from avidin-FITC fluorescence signals analyzed using a fluorescence microscope. The patterning of biomolecules on the CNT microarray platform using ultrafine APPJ provides a means for potential application of microarray biosensors based on CNTs.

  14. Evaluation of Multi-Year Continuous Measurements of Ultrafine Particles at Two Near-Road Stations in Toronto, Canada

    Science.gov (United States)

    Su, Y.; Sofowote, U.; Debosz, J.; Munoz, T.; Whitelaw, C.

    2013-12-01

    Particles with an aerodynamic diameter less than 100 nanometre (nm) are referred to as ultrafine particles (UFPs). Relative to fine and course particles, UFPs have greater potential to be suspended in air for a longer time and absorb toxic chemicals due to their larger surface areas per unit mass. UFPs could penetrate deep into the respiratory or cardiovascular systems and pose adverse health effects. In urban environments, primary sources of UFPs are from road traffic emissions and account for most of the total particle numbers. Controls on UPFs rely on better understanding of their emission sources and environmental behaviour. Ontario Ministry of the Environment have monitored UFPs since 2010 at two near-road stations in Toronto by using TSI 3031 UFP monitors. The two monitoring stations are approximately 20-30 meters adjacent to major arterial roads with over 20,000 vehicles per day. UFPs concentrations were monitored using six size channels: 20-30nm, 30-50nm, 50-70nm, 70-100nm, 100-200nm, and 200-450nm. Data are collected at time intervals of 11 or 15 minutes and averaged hourly. Concurrent measurements include wind speeds, wind directions, and concentrations of other air pollutants such as nitrogen oxides and black carbon. Data influenced by road-side traffic emissions were filtered by wind direction within 45° of normal to the road and wind speed greater than 1 m/s. Number concentrations were found higher for particles with sizes of 20-30nm and 30-50nm than for other sizes of UFPs. The observed particle number distributions are generally consistent with the theoretical understanding of particle nuclei mode and accumulation mode. During the day, for UFPs with sizes of 20-30nm and 30-50nm, elevated number concentrations were observed in morning traffic hours and to a less extent in the late afternoon. The elevated UFPs number concentrations coincided with nitrogen oxides and black carbon. Moreover, higher number concentrations were found on weekdays than

  15. Seasonal variations of ultra-fine and submicron aerosols in Taipei, Taiwan: implications for particle formation processes in a subtropical urban area

    Science.gov (United States)

    Cheung, H. C.; Chou, C. C.-K.; Chen, M.-J.; Huang, W.-R.; Huang, S.-H.; Tsai, C.-Y.; Lee, C. S. L.

    2016-02-01

    The aim of this study is to investigate the seasonal variations in the physicochemical properties of atmospheric ultra-fine particles (UFPs, d ≤ 100 nm) and submicron particles (PM1, d ≤ 1 µm) in an east Asian urban area, which are hypothesized to be affected by the interchange of summer and winter monsoons. An observation experiment was conducted at TARO (Taipei Aerosol and Radiation Observatory), an urban aerosol station in Taipei, Taiwan, from October 2012 to August 2013. The measurements included the mass concentration and chemical composition of UFPs and PM1, as well as the particle number concentration (PNC) and the particle number size distribution (PSD) with size range of 4-736 nm. The results indicated that the mass concentration of PM1 was elevated during cold seasons with a peak level of 18.5 µg m-3 in spring, whereas the highest concentration of UFPs was measured in summertime with a mean of 1.64 µg m-3. Moreover, chemical analysis revealed that the UFPs and PM1 were characterized by distinct composition; UFPs were composed mostly of organics, whereas ammonium and sulfate were the major constituents of PM1. The seasonal median of total PNCs ranged from 13.9 × 103 cm-3 in autumn to 19.4 × 103 cm-3 in spring. Median concentrations for respective size distribution modes peaked in different seasons. The nucleation-mode PNC (N4 - 25) peaked at 11.6 × 103 cm-3 in winter, whereas the Aitken-mode (N25 - 100) and accumulation-mode (N100 - 736) PNC exhibited summer maxima at 6.0 × 103 and 3.1 × 103 cm-3, respectively. The change in PSD during summertime was attributed to the enhancement in the photochemical production of condensable organic matter that, in turn, contributed to the growth of aerosol particles in the atmosphere. In addition, clear photochemical production of particles was observed, mostly in the summer season, which was characterized by average particle growth and formation rates of 4.0 ± 1.1 nm h-1 and 1.4 ± 0.8 cm-3 s-1

  16. Complex nanominerals and ultrafine particles assemblages in phosphogypsum of the fertilizer industry and implications on human exposure.

    Science.gov (United States)

    Silva, Luis F O; Hower, James C; Izquierdo, Maria; Querol, Xavier

    2010-10-01

    Phosphogypsum (CaSO(4).2H(2)O), a by-product of phosphate-rock processing, contains high amounts of impurities such P(2)O(5), F, radioactive elements, organic substances, secondary nanominerals, and ultrafine particles (UFP) enriched in metals and metalloids. In this study, we examine phosphogypsum (PG) collected from abandoned fertilizer industry facility in south Brazil (Santa Catarina state). The fragile nature of nanominerals and UFP assemblages from fertilizer industry systems required novel techniques and experimental approaches. The investigation of the geochemistry of complex nanominerals and UFP assemblages was a prerequisite to accurately assess the environmental and human health risks of contaminants and cost-effective chemical and biogeological remediation strategies. Particular emphasis was placed on the study and characterization of the complex mixed nanominerals and UFP containing potentially toxic elements. Nanometer-sized phases in PG were characterized using energy-dispersive X-ray spectrometer (EDS), field-emission scanning electron microscope (FE-SEM), and high-resolution transmission electron microscopy (HR-TEM) images. The chemical composition and possible correlations with morphology of nanominerals and UFP, as well as aspects of nanominerals and UFP, are discussed in the context of human health exposure, as well as in relation to management of the nanominerals and UFP in PG environments.

  17. Complex nanominerals and ultrafine particles assemblages in phosphogypsum of the fertilizer industry and implications on human exposure

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Luis F.O., E-mail: felipeqma@yahoo.com.br [Catarinense Institute of Environmental Research and Human Development-IPADHC, Capivari de Baixo, Santa Catarina (Brazil); Hower, James C. [University of Kentucky Center for Applied Energy Research, Lexington, KY, 40511 (United States); Izquierdo, Maria; Querol, Xavier [Institute of Environmental Assessment and Water Research (IDAEA-CSIC) C/Lluis Sole y Sabaris s/n, 08028 Barcelona (Spain)

    2010-10-01

    Phosphogypsum (CaSO{sub 4}.2H{sub 2}O), a by-product of phosphate-rock processing, contains high amounts of impurities such P{sub 2}O{sub 5}, F, radioactive elements, organic substances, secondary nanominerals, and ultrafine particles (UFP) enriched in metals and metalloids. In this study, we examine phosphogypsum (PG) collected from abandoned fertilizer industry facility in south Brazil (Santa Catarina state). The fragile nature of nanominerals and UFP assemblages from fertilizer industry systems required novel techniques and experimental approaches. The investigation of the geochemistry of complex nanominerals and UFP assemblages was a prerequisite to accurately assess the environmental and human health risks of contaminants and cost-effective chemical and biogeological remediation strategies. Particular emphasis was placed on the study and characterization of the complex mixed nanominerals and UFP containing potentially toxic elements. Nanometer-sized phases in PG were characterized using energy-dispersive X-ray spectrometer (EDS), field-emission scanning electron microscope (FE-SEM), and high-resolution transmission electron microscopy (HR-TEM) images. The chemical composition and possible correlations with morphology of nanominerals and UFP, as well as aspects of nanominerals and UFP, are discussed in the context of human health exposure, as well as in relation to management of the nanominerals and UFP in PG environments.

  18. Contribution of various microenvironments to the daily personal exposure to ultrafine particles

    DEFF Research Database (Denmark)

    Bekö, Gabriel; Kjeldsen, Birthe Uldahl; Olsen, Yulia;

    2015-01-01

    a backpack equipped with a portable monitor, continuously recording particle number concentrations (PN), in order to measure the real-time individual exposure over a period of similar to 48 h. A GPS logger was carried along with the particle monitor and allowed us to estimate the contribution of UFP exposure...

  19. Cyto- and genotoxicity of ultrafine TiO2 particles in cultured human lymphoblastoid cells.

    Science.gov (United States)

    Wang, Jing J; Sanderson, Barbara J S; Wang, He

    2007-04-01

    Titanium dioxide is frequently used in the production of paints, paper, plastics, welding rod-coating material, and cosmetics, because of its low toxicity. However, recent studies have shown that nano-sized or ultrafine TiO(2) (UF-TiO(2)) (<100 nm in diameter) can generate pulmonary fibrosis and lung tumor in rats. Cytotoxicity induced by UF-TiO(2) in rat lung alveolar macrophages was also observed. This generates great concern about the possible adverse effects of UF-TiO(2) for humans. The cytotoxicity and genotoxicity of UF-TiO(2) were investigated using the methyl tetrazolium cytotoxicity (MTT) assay, the population growth assay, the apoptosis assay by flow cytometry, the cytokinesis block micronucleus (CBMN) assay, the comet assay, and the hypoxanthine-guanine phosphoribosyltransferase (HPRT) gene mutation assay. WIL2-NS cells were incubated for 6, 24 and 48 h with 0, 26, 65 and 130 microg/ml UF-TiO(2). Significant decreases in viability were seen in the MTT assay at higher doses; for example, 61, 7 and 2% relative viability at 130 microg/ml for 6, 24 and 48-h exposure (P<0.01). A dose-dependent relationship was observed, while a time-dependent relationship was seen only at the highest dose (130 microg/ml) after exposure for 24 and 48 h. Treatment with 130 microg/ml UF-TiO(2) induced approximately 2.5-fold increases in the frequency of micronucleated binucleated cells (P<0.01). In addition, a significant reduction in the cytokinesis block proliferation index was observed by the CBMN assay (P<0.05). In the comet assay, treatment with 65 microg/ml UF-TiO(2) induced approximately 5-fold increases in olive tail moment (P<0.05). In the HPRT mutation assay, treatment with 130 microg/ml UF-TiO(2) induced approximately 2.5-fold increases in the mutation frequency (P<0.05). The results of this study indicate that UF-TiO(2) can cause genotoxicity and cytotoxicity in cultured human cells.

  20. Studying passive ultrafine particle dispersion in a room with a heat source

    DEFF Research Database (Denmark)

    Ardkapan, Siamak Rahimi; Nielsen, Peter V.; Afshari, Alireza

    2014-01-01

    of passive particles in a room with displacement ventilation system. In addition, some experiments are performed to verify the accuracy of the simulation results. According to the comparison of the experiment and the simulations in front of supply opening, the k–ε model seems to give better results than...... the k–ω model. It is shown that, in order to have an accurate result, the simulation of radiation effect is essential. Furthermore, the results of particle simulations show that when the passive particle source is in the height of 1.5 m and the heater is at the height of 0.5 m, the average concentration...

  1. Size controllable synthesis of ultrafine spherical gold particles and their simulation of plasmonic and SERS behaviors

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Zao [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, Sichuan (China); College of Physics and Electronics, Central South University, Changsha 410083 (China); Science and Technology on Plasma Physics Laboratory, China Academy of Engineering Physics, Mianyang 621900 (China); Xu, Xibin [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, Sichuan (China); College of Physics and Electronics, Central South University, Changsha 410083 (China); Luo, Jiangshan; Li, Xibo [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, Sichuan (China); Science and Technology on Plasma Physics Laboratory, China Academy of Engineering Physics, Mianyang 621900 (China); Yi, Yong [Joint Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology and Research Center of Laser Fusion, Mianyang (China); Jiang, Xiaodong [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, Sichuan (China); Yi, Yougen, E-mail: yougenyi@mail.csu.edu.cn [College of Physics and Electronics, Central South University, Changsha 410083 (China); Tang, Yongjian [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, Sichuan (China); Science and Technology on Plasma Physics Laboratory, China Academy of Engineering Physics, Mianyang 621900 (China)

    2014-04-01

    A simple and reproducible way was explored to synthesize quasi-spherical gold particles with different size distributions in water by rapidly adding a mixture solution of HAuCl{sub 4}, sodium citrate, and a trace amount of silver nitrate. By careful tuning of the reaction parameters, mono-disperse gold particles with the diameter of 5–220 nm can be obtained controllably. The particle size of 130 nm for the particles film showed the highest SERS activity with the 632.8 nm excitation. The theoretical calculations of the UV–vis extinction spectra can be directly compared with experiments by using the discrete-dipole approximation (DDA). Control of nanostructure shape allows optimization of plasmon resonance for molecular detection and spectroscopy.

  2. Surface conductivity dependent dynamic behaviour of an ultrafine atmospheric pressure plasma jet for microscale surface processing

    Science.gov (United States)

    Abuzairi, Tomy; Okada, Mitsuru; Bhattacharjee, Sudeep; Nagatsu, Masaaki

    2016-12-01

    An experimental study on the dynamic behaviour of microcapillary atmospheric pressure plasma jets (APPJs) with 5 μm tip size for surfaces of different conductivity is reported. Electrical and spatio-temporal characteristics of the APPJs are monitored using high voltage probe, current monitor and high speed intensified charge couple device camera. From these experimental results, we presented a simple model to understand the electrical discharge characteristics of the capillary APPJs with double electrodes, and estimated the velocity of the ionization fronts in the jet and the electron density to be 3.5-4.2 km/s and 2-7 × 1017 m-3. By analyzing the dynamics of the microcapillary APPJs for different substrate materials, it was found that the surface irradiation area strongly depended on the substrate conductivity and permittivity, especially in the case of polymer-like substrate, surface irradiation area was significantly broadened probably due to the repelling behaviour of the plasma jets from the accumulated electrical charges on the polymer surface. The effect of applying a substrate bias in the range from -900 V to +900 V on the plasma irradiation onto the substrates was also investigated. From the knowledge of the present results, it is helpful for choosing the substrate materials for microscale surface modification.

  3. Ultrafine particle sources and in-situ formation in a European megacity

    Directory of Open Access Journals (Sweden)

    M. Pikridas

    2015-02-01

    Full Text Available Ambient particle number size distributions were measured in Paris, France during summer (1–31 July 2009 and winter (15 January–15 February 2010 at three fixed ground sites and using two mobile laboratories and one airplane. The campaigns were part of the MEGAPOLI project. New particle formation (NPF was observed only during summer at approximately 50% of the campaign days, assisted by the low condensation sink (about 10.7 ± 5.9 × 10−3 s−1. NPF events inside the Paris plume were also observed at 600 m altitude onboard an aircraft simultaneously with regional events identified on the ground. Increased particle number concentrations were measured aloft also outside of the Paris plume at the same altitude, and were attributed to NPF. The Paris plume was identified, based on increased particle number and black carbon concentration, up to 200 km away from Paris center during summer. The number concentration of particles with diameter exceeding 2.5 nm measured on the surface at Paris center was on average 6.9 ± 8.7 × 104 and 12.1 ± 8.6 × 104 cm−3 during summer and winter, respectively, and was found to decrease exponentially with distance from Paris. However, further than 30 km from the city center, the particle number concentration at the surface was similar during both campaigns. During summer one suburban site in the NE was not significantly affected by Paris emissions due to higher background number concentrations, while the particle number concentration at the second suburban site in the SW increased by a factor of three when it was downwind of Paris.

  4. Capture Efficiency of Cooking-Related Fine and Ultrafine Particles by Residential Exhaust Hoods

    Energy Technology Data Exchange (ETDEWEB)

    Lunden, Melissa M.; Delp, William W.

    2014-06-05

    Effective exhaust hoods can mitigate the indoor air quality impacts of pollutant emissions from residential cooking. This study reports capture efficiencies (CE) measured for cooking generated particles for scripted cooking procedures in a 121-m3 chamber with kitchenette. CEs also were measured for burner produced CO2 during cooking and separately for pots and pans containing water. The study used four exhaust hoods previously tested by Delp and Singer (Environ. Sci. Technol., 2012, 46, 6167-6173). For pan-frying a hamburger over medium heat on the back burner, CEs for particles were similar to those for burner produced CO2 and mostly above 80percent. For stir-frying green beans in a wok (high heat, front burner), CEs for burner CO2 during cooking varied by hood and airflow: CEs were 34-38percent for low (51?68 L s-1) and 54?72percent for high (109?138 L s-1) settings. CEs for 0.3?2.0 ?m particles during front burner stir-frying were 3?11percent on low and 16?70percent on high settings. Results indicate that CEs measured for burner CO2 are not predictive of CEs of cooking-generated particles under all conditions, but they may be suitable to identify devices with CEs above 80percent both for burner combustion products and for cooking-related particles.

  5. Atmospheric and environmental impacts of volcanic ash particle emissions

    Science.gov (United States)

    Durant, Adam

    2010-05-01

    Globally, at any one time, there may be 20 volcanoes erupting that collectively emit a constant flux of gases and aerosol, including silicate particles (tephra), to the atmosphere which influences processes including cloud microphysics, heterogeneous chemistry and radiative balance. The nature and impact of atmospheric volcanic particle fluxes depend on total mass erupted, emission rate, emission source location, physical and chemical properties of the particles, and the location and residence time of the particles in the atmosphere. Removal of ash particles from the atmosphere through sedimentation is strongly influenced by particle aggregation through hydrometeor formation, and convective instabilities such as mammatus. I will address the following questions: What are the atmospheric impacts of volcanic ash emissions? What controls the residence time of volcanic particles in the atmosphere? What affects particle accumulation at the surface? And what are the human and environmental impacts of ash fallout?

  6. Effects of Particle Filters and Accelerated Engine Replacement on Heavy-Duty Diesel Vehicle Emissions of Black Carbon, Nitrogen Oxides, and Ultrafine Particles

    Science.gov (United States)

    Kirchstetter, T.; Preble, C.; Dallmann, T. R.; DeMartini, S. J.; Tang, N. W.; Kreisberg, N. M.; Hering, S. V.; Harley, R. A.

    2013-12-01

    Diesel particle filters have become widely used in the United States since the introduction in 2007 of a more stringent exhaust particulate matter emission standard for new heavy-duty diesel vehicle engines. California has instituted additional regulations requiring retrofit or replacement of older in-use engines to accelerate emission reductions and air quality improvements. This presentation summarizes pollutant emission changes measured over several field campaigns at the Port of Oakland in the San Francisco Bay Area associated with diesel particulate filter use and accelerated modernization of the heavy-duty truck fleet. Pollutants in the exhaust plumes of hundreds of heavy-duty trucks en route to the Port were measured in 2009, 2010, 2011, and 2013. Ultrafine particle number, black carbon (BC), nitrogen oxides (NOx), and nitrogen dioxide (NO2) concentrations were measured at a frequency ≤ 1 Hz and normalized to measured carbon dioxide concentrations to quantify fuel-based emission factors (grams of pollutant emitted per kilogram of diesel consumed). The size distribution of particles in truck exhaust plumes was also measured at 1 Hz. In the two most recent campaigns, emissions were linked on a truck-by-truck basis to installed emission control equipment via the matching of transcribed license plates to a Port truck database. Accelerated replacement of older engines with newer engines and retrofit of trucks with diesel particle filters reduced fleet-average emissions of BC and NOx. Preliminary results from the two most recent field campaigns indicate that trucks without diesel particle filters emit 4 times more BC than filter-equipped trucks. Diesel particle filters increase emissions of NO2, however, and filter-equipped trucks have NO2/NOx ratios that are 4 to 7 times greater than trucks without filters. Preliminary findings related to particle size distribution indicate that (a) most trucks emitted particles characterized by a single mode of approximately

  7. An electrical sensor for long-term monitoring of ultrafine particles in workplaces

    Science.gov (United States)

    Lanki, Timo; Tikkanen, Juha; Janka, Kauko; Taimisto, Pekka; Lehtimäki, Matti

    2011-07-01

    Pegasor Oy Ltd. (Finland) has developed a diffusion charging measurement device that enables continuous monitoring of fine particle concentration at a low initial and lifecycle cost. The innovation, for which an international process and apparatus patent has been applied for, opens doors for monitoring nanoparticle concentrations in workplaces. The Pegasor Particle Sensor (PPS) operates by electrostatically charging particles passing through the sensor and then measuring the current caused by the charged particles as they leave the sensor. The particles never touch the sensor and so never accumulate on its surfaces or need to be cleaned off. The sensor uses an ejector pump to draw a constant sample flow into the sensing area where it is mixed with the clean, charged pump flow air (provided by an external source). The sample flow containing charged particles passes through the sensor. The current generated by the charge leaving the detection volume is measured and related to the particle surface area. This system is extremely simple and reliable - no contact, no moving parts, and all critical parts of the sensor are constantly cleaned by a stream of fresh, filtered air. Due to the ejector pump, the sample flow, and respectively the sensor response is independent of the flow and pressure conditions around the sampling inlet. Tests with the Pegasor Particle Sensor have been conducted in a laboratory, and at a workplace producing nanoparticles for glass coatings. A new measurement protocol has been designed to ensure that process workers are not exposed to unusually high nanoparticle concentrations at any time during their working day. One sensor is placed inside the process line, and a light alarm system indicates the worker not to open any protective shielding or ventilation systems before concentration inside has reached background levels. The benefits of PPS in industrial hygiene are that the same monitoring technology can be used at the source as well as at the

  8. Ultrafine Particle Metrics and Research Considerations: Review of the 2015 UFP Workshop

    Directory of Open Access Journals (Sweden)

    Richard W. Baldauf

    2016-10-01

    Full Text Available In February 2015, the United States Environmental Protection Agency (EPA sponsored a workshop in Research Triangle Park, NC, USA to review the current state of the science one missions, air quality impacts, and health effects associated with exposures to ultrafine particles[1].[...

  9. Estimation of ultrafine particle concentrations at near-highway residences using data from local and central monitors

    Science.gov (United States)

    Fuller, Christina H.; Brugge, Doug; Williams, Paige L.; Mittleman, Murray A.; Durant, John L.; Spengler, John D.

    2012-09-01

    Ultrafine particles (UFP; aerodynamic diameter predict hourly UFP concentration measured at residences in an urban community with a major interstate highway and; (2) determine if meteorology and proximity to traffic improve explanatory power. Short-term (1-3 weeks) residential monitoring of UFP concentration was conducted at 18 homes. Long-term monitoring was conducted at two near-highway monitoring sites and a central site. We created models of outdoor residential UFP concentration based on concentrations at the near-highway site, at the central site, at both sites together and without fixed sites. UFP concentration at residential sites was more highly correlated with those at a near-highway site than a central site. In regression models of each site alone, a 10% increase in UFP concentration at a near-highway site was associated with a 6% (95% CI: 6%, 7%) increase at residences while a 10% increase in UFP concentration at the central site was associated with a 3% (95% CI: 2%, 3%) increase at residences. A model including both sites showed minimal change in the magnitude of the association between the near-highway site and the residences, but the estimated association with UFP concentration at the central site was substantially attenuated. These associations remained after adjustment for other significant predictors of residential UFP concentration, including distance from highway, wind speed, wind direction, highway traffic volume and precipitation. The use of a central site as an estimate of personal exposure for populations near local emissions of traffic-related air pollutants may result in exposure misclassification.

  10. Characteristics of ultrafine particle from a compression-ignition engine fueled with low sulfur diesel

    Institute of Scientific and Technical Information of China (English)

    LIU Wei; ZHANG WuGao; LEI Zhu; LI XinLing; HUANG Zhen

    2009-01-01

    Number size distributions (NSDs, 10-487 nm) and composition of nanoparticle emitted from an engine fueled with ordinary diesel (OD) and low sulfur diesel (LSD) fuel were comparatively studied. The re-suits indicate that, compared with the OD, the LSD was found to slightly decrease the mass concentra-tion, and significantly reduce the number concentration of the total particles (10-487 nm), and the reduction of number increased with the speed and load of engine. The NSD for the two fuels showed a similar bimodal structure under all test engine conditions. Under the same engine conditions, the nu-cleation mode for LSD fuel was significantly lower than that of ordinary diesel. However, the accumu-lation mode for the two fuels showed little difference. The elements composition of exhaust particles included C, O, Cl, S, Si, Ca, Na, Al and K. The S element was not detected in LSD fuel case. The main component of soluble organic fraction (SOF) of exhaust particles for the two fuels included saturated alkane (C15-C26), ester and polycyclic aromatic hydrocarbons (PAHs). However, PAHs were not found in LSD fuel case.

  11. Assessment of ultrafine particles and noise measurements using fuzzy logic and data mining techniques.

    Science.gov (United States)

    Fernández-Camacho, R; Brito Cabeza, I; Aroba, J; Gómez-Bravo, F; Rodríguez, S; de la Rosa, J

    2015-04-15

    This study focuses on correlations between total number concentrations, road traffic emissions and noise levels in an urban area in the southwest of Spain during the winter and summer of 2009. The high temporal correlation between sound pressure levels, traffic intensity, particle number concentrations related to traffic, black carbon and NOx concentrations suggests that noise is linked to traffic emissions as a main source of pollution in urban areas. First, the association of these different variables was studied using PreFuRGe, a computational tool based on data mining and fuzzy logic. The results showed a clear association between noise levels and road-traffic intensity for non-extremely high wind speed levels. This behaviour points, therefore, to vehicular emissions being the main source of urban noise. An analysis for estimating the total number concentration from noise levels is also proposed in the study. The high linearity observed between particle number concentrations linked to traffic and noise levels with road traffic intensity can be used to calculate traffic related particle number concentrations experimentally. At low wind speeds, there are increases in noise levels of 1 dB for every 100 vehicles in circulation. This is equivalent to 2000 cm(-3) per vehicle in winter and 500 cm(-3) in summer. At high wind speeds, wind speed could be taken into account. This methodology allows low cost sensors to be used as a proxy for total number concentration monitoring in urban air quality networks.

  12. Mass and elemental distributions of atmospheric particles nearby blast furnace and electric arc furnace operated industrial areas in Australia.

    Science.gov (United States)

    Mohiuddin, Kazi; Strezov, Vladimir; Nelson, Peter F; Stelcer, Eduard; Evans, Tim

    2014-07-15

    The improved understanding of mass and elemental distributions of industrial air particles is important due to their heterogeneous atmospheric behaviour and impact on human health and the environment. In this study, particles of different size ranges were collected from three sites in Australia located in the vicinity of iron and steelmaking industries and one urban background site with very little industrial influence. In order to determine the importance of the type of industrial activity on the urban atmospheric quality, the industrial sites selected in this study were in the close proximity to two blast furnace operated and one electric arc furnace based steelmaking sites. The chemical compositions of the collected air particles were analysed using the proton induced X-ray emission (PIXE) technique. This study revealed significantly higher metal concentrations in the atmospheric particles collected in the industrial sites, comparing to the background urban site, demonstrating local influence of the industrial activities to the air quality. The modality types of the particles were found to be variable between the mass and elements, and among elements in the urban and industrial areas indicating that the elemental modal distribution is as important as particle mass for particle pollution modelling. The highest elemental number distribution at all studied sites occurred with particle size of 0.1 μm. Iron was found as the main dominant metal at the industrial atmosphere in each particle size range. The industrial Fe fraction in the submicron and ultrafine size particles was estimated at up to 95% which may be released from high temperature industrial activities with the iron and steelmaking industries being one of the major contributors. Hence, these industrial elemental loadings can highly influence the atmospheric pollution at local urban and regional levels and are required to consider in the atmospheric modelling settings.

  13. Daily variation in the properties of urban ultrafine aerosol—Part I: Physical characterization and volatility

    Science.gov (United States)

    Moore, Katharine F.; Ning, Zhi; Ntziachristos, Leonidas; Schauer, James J.; Sioutas, Constantinos

    A summer air quality monitoring campaign focusing on the evolution of ultrafine (data suggest the strong influence of commute traffic emissions on morning observations of ultrafine particle concentrations. By contrast, in the afternoon our measurements provide evidence of secondary photochemical reactions becoming the predominant formation mechanism of ultrafine aerosols. The ultrafine number concentration peak occurs in the early afternoon, before the maximum ozone concentration is observed. The source of this offset is unknown and requires further investigation. It is possible that the chemical mechanisms responsible for secondary organic aerosol formation evolve as atmospheric conditions change and/or secondary semi-volatile components of the aerosol re-volatilize due to the elevated peak temperatures observed (ca. 30-35 °C) combined with the increased atmospheric dilution during that time. Measurements of the volatility of the ultrafine aerosol are consistent with this interpretation as overall volatility increases in the afternoon and there is less evidence of external mixing. Composition data presented in the companion paper support these conclusions [Ning et al., 2007. Daily variation in chemical characteristics of urban ultrafine aerosols and inference of their sources. Environmental Science and Technology, in press].

  14. PAH, BTEX, carbonyl compound, black-carbon, NO2 and ultrafine particle dynamometer bench emissions for Euro 4 and Euro 5 diesel and gasoline passenger cars

    Science.gov (United States)

    Louis, Cédric; Liu, Yao; Tassel, Patrick; Perret, Pascal; Chaumond, Agnès; André, Michel

    2016-09-01

    Although implementing Diesel particulate filters (DPF) and other novel aftertreatment technologies makes it possible to achieve significant reductions in particle mass emissions, it may induce the release of ultrafine particles and emissions of many other unregulated compounds. This paper focuses on (i) ultrafine particles, black carbon, BTEX, PAH, carbonyl compounds, and NO2 emissions from Euro 4 and Euro 5 Diesel and gasoline passenger cars, (ii) the influence of driving conditions (e.g., cold start, urban, rural and motorway conditions), and (iii) the impact of additive and catalysed DPF devices on vehicle emissions. Chassis dynamometer tests were conducted on four Euro 5 vehicles and two Euro 4 vehicles: gasoline vehicles with and without direct injection system and Diesel vehicles equipped with additive and catalysed particulate filters. The results showed that compared to hot-start cycles, cold-start urban cycles increased all pollutant emissions by a factor of two. The sole exception was NO2, which was reduced by a factor of 1.3-6. Particulate and black carbon emissions from the gasoline engines were significantly higher than those from the Diesel engines equipped with DPF. Moreover, the catalysed DPF emitted about 3-10 times more carbonyl compounds and particles than additive DPF, respectively, during urban driving cycles, while the additive DPF vehicles emitted 2 and 5 times more BTEX and carbonyl compounds during motorway driving cycles. Regarding particle number distribution, the motorway driving cycle induced the emission of particles smaller in diameter (mode at 15 nm) than the urban cold-start cycle (mode at 80-100 nm). The results showed a clear positive correlation between particle, black carbon, and BTEX emissions, and a negative correlation between particles and NO2.

  15. Progress in the Analysis of Complex Atmospheric Particles

    Energy Technology Data Exchange (ETDEWEB)

    Laskin, Alexander; Gilles, Mary K.; Knopf, Daniel A.; Wang, Bingbing; China, Swarup

    2016-06-16

    This manuscript presents an overview on recent advances in field and laboratory studies of atmospheric particles formed in processes of environmental air-surfaces interactions. The overarching goal of these studies is to advance predictive understanding of atmospheric particle composition, particle chemistry during aging, and their environmental impacts. The diversity between chemical constituents and lateral heterogeneity within individual particles adds to the chemical complexity of particles and their surfaces. Once emitted, particles undergo transformation via atmospheric aging processes that further modify their complex composition. We highlight a range of modern analytical approaches that enable multi-modal chemical characterization of particles with both molecular and lateral specificity. When combined, they provide a comprehensive arsenal of tools for understanding the nature of particles at air-surface interactions and their reactivity and transformations with atmospheric aging. We discuss applications of these novel approaches in recent studies and highlight additional research areas to explore environmental effects of air-surface interactions.

  16. Progress in the Analysis of Complex Atmospheric Particles

    Science.gov (United States)

    Laskin, Alexander; Gilles, Mary K.; Knopf, Daniel A.; Wang, Bingbing; China, Swarup

    2016-06-01

    This article presents an overview of recent advances in field and laboratory studies of atmospheric particles formed in processes of environmental air-surface interactions. The overarching goal of these studies is to advance predictive understanding of atmospheric particle composition, particle chemistry during aging, and their environmental impacts. The diversity between chemical constituents and lateral heterogeneity within individual particles adds to the chemical complexity of particles and their surfaces. Once emitted, particles undergo transformation via atmospheric aging processes that further modify their complex composition. We highlight a range of modern analytical approaches that enable multimodal chemical characterization of particles with both molecular and lateral specificity. When combined, these approaches provide a comprehensive arsenal of tools for understanding the nature of particles at air-surface interactions and their reactivity and transformations with atmospheric aging. We discuss applications of these novel approaches in recent studies and highlight additional research areas to explore the environmental effects of air-surface interactions.

  17. Transport of particles in an atmospheric turbulent boundary layer

    Institute of Scientific and Technical Information of China (English)

    Xiongping Luo; Shiyi Chen

    2005-01-01

    A program incorporating the parallel code of large eddy simulation (LES) and particle transportation model is developed to simulate the motion of particles in an atmospheric turbulent boundary layer (ATBL). A model of particles of 100-micrometer order coupling with large scale ATBL is proposed. Two typical cases are studied, one focuses on the evolution of particle profile in the ATBL and the landing displacement of particles, whereas the other on the motion of particle stream.

  18. Atmospheric ultrafine aerosol number concentration and its correlation with vehicular flow at two sites in the western Himalayan region: Kullu-Manali, India

    Indian Academy of Sciences (India)

    Nand L Sharma; Jagdish C Kuniyal; Mahavir Singh; Priyanka Sharma; Kesar Chand; Ajay Kumar Negi; Manum Sharma; Harinder Kumar Thakur

    2011-04-01

    The concentration of ultrafine aerosol particles of aitken and nucleation mode having size in the range of 1–20 nm was monitored with water-based Condensation Particle Counter. The monitoring was carried out from midnight-to-midnight in every alternate day on a fortnightly basis to represent summer, monsoon and winter (autumn) seasons of 2008 at Mohal (1154 m amsl) and Kothi (2530 m amsl) in Kullu-Manali area of the northwestern Himalayan region of India. The results indicate that diurnal pattern has faint bimodal structure with two peaks, one in morning and the other in evening at both the sites but it is not as distinct as found in plains. There is rather a constant particle density pattern of large magnitude consistent with vehicular movement from morning till evening. The monthly 24 h average particle density gradually picks up from January, increases rapidly in summer months and then decreases in monsoon season at Mohal but at Kothi it keeps on rising from April to October with a slight more increase in September. The particle density is more in summer than in monsoon season at Mohal, a trend opposite to plains. It may be due to the development of warm thermal layer on valley floor while a cold layer develops along snowy hilltops in winter leading to convection of fine particle up the slopes of valley during daytime. At Kothi, the trend is same as it is in continental plains but opposite to Mohal. The relatively more value of particle density in September and October at both the sites may be due to month long International Kullu Dussehra fair in the valley. The vehicular survey conducted agrees well with entire study period averaged diurnal variations and monthly 24 h averaged value of fine particle density. The average value of ultrafine particle density at each hour of a day for entire study period is 20369 ± 1230 Ncm−3 and 14389 ± 1464 Ncm−3 at Mohal and Kothi sites, respectively. The comparison with earlier results shows a significant increase

  19. Microwave absorption properties of dielectric La{sub 1.5}Sr{sub 0.5}NiO{sub 4} ultrafine particles

    Energy Technology Data Exchange (ETDEWEB)

    Tho, P.T.; Xuan, C.T.A. [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang-Quoc-Viet, Hanoi (Viet Nam); College of Sciences, Thai-nguyen University, Thai-nguyen (Viet Nam); Quang, D.M. [Department of Physics, Hanoi National University, Hanoi (Viet Nam); Bach, T.N.; Thanh, T.D.; Le, N.T.H.; Manh, D.H.; Phuc, N.X. [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang-Quoc-Viet, Hanoi (Viet Nam); Nam, D.N.H., E-mail: daonhnam@yahoo.com [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang-Quoc-Viet, Hanoi (Viet Nam)

    2014-08-01

    Highlights: • Colossal permittivity La{sub 1.5}Sr{sub 0.5}NiO{sub 4} ultrafine particles are prepared. • The particles have weak paramagnetic behavior at 300 K. • La{sub 1.5}Sr{sub 0.5}NiO{sub 4} particles/wax composites exhibit strong microwave absorption. • Impedance matching is responsible for the absorption resonances. - Abstract: La{sub 2−x}Sr{sub x}NiO{sub 4} compounds are well known dielectric materials that have colossal permittivities (ε{sub R} > 10{sup 7}). In the present work, the powder of La{sub 1.5}Sr{sub 0.5}NiO{sub 4} ultrafine particles was prepared by a combinatorial method of solid-state reaction and high-energy ball milling. Magnetic measurements, M(H), show a very small magnetization and paramagnetic characteristics at room temperature. Flat layers of La{sub 2−x}Sr{sub x}NiO{sub 4}/paraffin mixture of different thicknesses (t) exhibits strong microwave absorption resonances in the 4–18 GHz range. The reflection loss (RL) decreases with t and reaches down to −36.7 dB for t = 3.0 mm. The impedance matching (|Z| = Z{sub 0} = 377 Ω), rather than the phase matching mechanism, is found responsible for the resonance for 1.5 mm ≤ t ≤ 3.0 mm. Further increase in the thickness leads to |Z| > Z{sub 0} at all frequencies and a reduced absorption. The influence of non-metal backing is also discussed. The obtained low RL suggests that La{sub 1.5}Sr{sub 0.5}NiO{sub 4} particles could be a potential filler for high performance radar absorbing material.

  20. Parameterization of ionization induced in the atmosphere by precipitating particles

    Science.gov (United States)

    Artamonov, Anton; Usoskin, Ilya; Kovaltsov, Gennady

    We present a physical model to calculate ionization induced in the atmosphere by precipitating particles. This model is based on the Bethe-Bloch equation applied for precipitating particles such as: electrons, alpha-particles and protons. The energy range of precipitating particles is up to 5MeV and 80MeV/nuc respectively. This model provides an easy implementation with a robust realization of model calculations for a wide range of incident energies of precipitating particles. This method is limited to the upper-middle atmosphere. An ionization yield function [see, Usoskin and Kovaltsov, 2006; Usoskin, Kovaltsov, Mironova, 2010] can be also used in this model, making it possible to calculate the atmospheric ionization effect of precipitating particles for the entire atmosphere, dawn to the ground.

  1. New particle formation and growth in CMAQ via application of comprehensive modal methods

    Science.gov (United States)

    The formation and growth of new atmospheric ultrafine particles are exceedingly complex processes and recent scientific efforts have grown our understanding of them tremendously. This presentation describes the effort to apply this new knowledge to the CMAQ chemical transport mod...

  2. Mass and elemental distributions of atmospheric particles nearby blast furnace and electric arc furnace operated industrial areas in Australia

    Energy Technology Data Exchange (ETDEWEB)

    Mohiuddin, Kazi, E-mail: kazi.mohiuddin@students.mq.edu.au [Graduate School of the Environment, Department of Environment and Geography, Faculty of Science, Macquarie University, NSW (Australia); Strezov, Vladimir; Nelson, Peter F. [Graduate School of the Environment, Department of Environment and Geography, Faculty of Science, Macquarie University, NSW (Australia); Stelcer, Eduard [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia); Evans, Tim [Graduate School of the Environment, Department of Environment and Geography, Faculty of Science, Macquarie University, NSW (Australia)

    2014-07-01

    The improved understanding of mass and elemental distributions of industrial air particles is important due to their heterogeneous atmospheric behaviour and impact on human health and the environment. In this study, particles of different size ranges were collected from three sites in Australia located in the vicinity of iron and steelmaking industries and one urban background site with very little industrial influence. In order to determine the importance of the type of industrial activity on the urban atmospheric quality, the industrial sites selected in this study were in the close proximity to two blast furnace operated and one electric arc furnace based steelmaking sites. The chemical compositions of the collected air particles were analysed using the proton induced X-ray emission (PIXE) technique. This study revealed significantly higher metal concentrations in the atmospheric particles collected in the industrial sites, comparing to the background urban site, demonstrating local influence of the industrial activities to the air quality. The modality types of the particles were found to be variable between the mass and elements, and among elements in the urban and industrial areas indicating that the elemental modal distribution is as important as particle mass for particle pollution modelling. The highest elemental number distribution at all studied sites occurred with particle size of 0.1 μm. Iron was found as the main dominant metal at the industrial atmosphere in each particle size range. The industrial Fe fraction in the submicron and ultrafine size particles was estimated at up to 95% which may be released from high temperature industrial activities with the iron and steelmaking industries being one of the major contributors. Hence, these industrial elemental loadings can highly influence the atmospheric pollution at local urban and regional levels and are required to consider in the atmospheric modelling settings. - Highlights: • Urban and

  3. Atmospheric sub-3 nm particles at high altitudes

    Directory of Open Access Journals (Sweden)

    S. Mirme

    2010-01-01

    Full Text Available Formation of new atmospheric aerosol particles is known to occur almost all over the world and the importance of these particles to climate and air quality has been recognized. Recently, it was found that atmospheric aerosol particle formation begins at the diameter of around 1.5–2.0 nm and a pool of sub-3 nm atmospheric particles – consisting of both charged and uncharged ones – was observed at the ground level. Here, we report on the first airborne observations of the pool of sub-3 nm neutral atmospheric particles. Between 2 and 3 nm, their concentration is roughly two orders of magnitude larger than that of the ion clusters, depending slightly on the altitude. Our findings indicate that new particle formation takes place throughout the tropospheric column up to the tropopause. Particles were found to be formed via neutral pathways in the boundary layer, and there was no sign of an increasing role by ion-induced nucleation toward the upper troposphere. Clouds, while acting as a source of sub-10 nm ions, did not perturb the overall budget of atmospheric clusters or particles.

  4. Atmospheric sub-3 nm particles at high altitudes

    Directory of Open Access Journals (Sweden)

    S. Mirme

    2009-09-01

    Full Text Available Formation of new atmospheric aerosol particles is known to occur almost all over the world and the importance of these particles to climate and air quality has been recognized. Recently, it was found that atmospheric aerosol formation begins at particle diameter of around 1.5–2.0 nm and a pool of sub-3 nm atmospheric particles – consisting of both charged and uncharged ones – was observed at the ground level. Here, we report on the first airborne observations of the pool of sub-3 nm neutral atmospheric particles. Between 2 and 3 nm, their concentration is roughly two orders of magnitude larger than that of the ion clusters, depending slightly on the altitude. Our findings indicate that new particle formation takes place actively throughout the tropospheric column up to the tropopause. Particles were found to be formed via neutral pathways in the boundary layer, and there was no sign of an increasing role by ion-induced nucleation toward the upper troposphere. Clouds, while acting as a source of sub-10 nm ions, did not perturb the overall budget of atmospheric clusters or particles.

  5. Morphology, composition, and atmospheric processing of soot particles

    Science.gov (United States)

    Slowik, Jay G.

    Combustion-generated soot aerosols play an important role in climate forcing due to their strong light-absorbing properties. Quantitative measurement of BC is challenging because BC often occurs in highly non-spherical soot particles of complex morphology. The task is further complicated because of the lack of an unambiguous chemical definition of the material. Here we present the development and application of a new technique for determining particle morphology and composition. Simultaneous measurements of mobility diameter, vacuum aerodynamic diameter, and non-refractory composition were used to determine the particle mass, volume, density, composition, dynamic shape factor, and fractal dimension. Under certain conditions, particle surface area and the number and size of the primary spherules composing the soot fractal aggregates were also determined. The particle characterization technique described above was applied to the following four studies: (1) Characterization of flame-generated soot particles. Depending on flame conditions, either fractal or near-spherical particles were generated and their properties interpreted in terms of the mechanism for soot formation. (2) Coating and denuding experiments were performed on soot particles. The results yielded information about morphology changes to the entire soot particle and to the internal black carbon structure due to atmospheric processing. The denuding experiments also provided particle surface area, which was used to determine the atmospheric lifetime of fractal soot particles relative to spheres. (3) An inter-comparison study of instruments measuring the black carbon content of soot particles was conducted. The detailed characterization of soot particles enabled a number of assumptions about the operation of the selected instruments to be tested. (4) Ambient particles were sampled in Mexico City. In the early morning, ambient particles were detected with a fractal morphology similar to that of diesel

  6. Evaluation of the Quick Urban and Industrial Complex (QUIC) Modeling System to Predict Ultrafine Particle Levels in an Urban Neighborhood near a Highway

    Science.gov (United States)

    St. Vincent, A.; Milando, C.; Zhu, S.; Zamore, W.; Brugge, D.; Durant, J.

    2010-12-01

    Exposure to vehicle-generated ultrafine particles (USA), and tested using wind conditions characteristic of the area. Model results were then compared to field data collected with a mobile air pollution monitoring laboratory. Generally good agreement was observed between the model results and field data for winds parallel and perpendicular to the highway. In addition, models that treated neighborhood blocks (i.e., collections of houses surrounded by four intersecting streets) as porous structures through which attenuated wind and UFP could pass performed better than models containing non-porous solid blocks or individual buildings. These results will help inform the development of a predictive UFP model that will be used as part of a cardiovascular health study being conducted in several neighborhoods near I-93 in Somerville.

  7. Multifractal analysis of atmospheric sub-micron particle data

    Science.gov (United States)

    Arizabalo, Rubén Darío; González-Ávalos, Eugenio; Korvin, Gabor

    2015-03-01

    Multifractal analysis was used to describe air pollution by sub-micrometric atmospheric particles. Atmospheric particle concentrations were studied from March 31 to April 21, 2006, as part of the MILAGRO campaign at the Jasso Station by means of an SMPS. Sixteen campaign days were selected to carry out the multifractal analysis of the experimental data through Singularity Spectra f(α). In this work, the roughness/smoothness feature of atmospheric particle distributions was studied by means of the Hölder exponent (α), which can be associated with the intensity of particle emissions through time and the randomness of the external emission sources. Multifractal analysis has been found to be a useful tool to establish intensity fluctuations of atmospheric data.

  8. Removal of Atmospheric Particles in Poor Visibility Outdoor Images

    Directory of Open Access Journals (Sweden)

    Yaseen Al-Zubaidy

    2013-08-01

    Full Text Available The visibility of a scene is degraded by weather phenomena such as rain drizzle, fog and haze. The degradation of image scene is due the substantial presence of particles in the atmosphere that scatter and absorb light. As the light spreads from object to the observer, the color and intensity is changed by the atmospheric particles. In this research, we suggest new methods to precisely detect airlight and correctly estimate the atmospheric veil from image that captured in bad weather. The result of suggested methods will be used in scattering atmospheric model to remove atmospheric particles namely, rain drizzle, fog and haze from a single image. Therefore a higher visibility image will be produced.

  9. New particle formation and growth in CMAQ: Application of comprehensive modal methods to observations during CalNex and CARES

    Science.gov (United States)

    The formation and growth of new atmospheric ultrafine particles are exceedingly complex processes and recent scientific efforts have grown our understanding of them tremendously. This presentation describes the effort to apply this new knowledge to the CMAQ chemical transport mod...

  10. Ultrafine particles affect the balance of endogenous pro- and anti-inflammatory lipid mediators in the lung: in-vitro and in-vivo studies

    Directory of Open Access Journals (Sweden)

    Beck-Speier Ingrid

    2012-07-01

    Full Text Available Abstract Background Exposure to ultrafine particles exerts diverse harmful effects including aggravation of pulmonary diseases like asthma. Recently we demonstrated in a mouse model for allergic airway inflammation that particle-derived oxidative stress plays a crucial role during augmentation of allergen-induced lung inflammation by ultrafine carbon particle (UfCP inhalation. The mechanisms how particle inhalation might change the inflammatory balance in the lungs, leading to accelerated inflammatory reactions, remain unclear. Lipid mediators, known to be immediately generated in response to tissue injury, might be strong candidates for priming this particle-triggered change of the inflammatory balance. Methods We hypothesize that inhalation of UfCP may disturb the balance of pro- and anti-inflammatory lipid mediators in: i a model for acute allergic pulmonary inflammation, exposing mice for 24 h before allergen challenge to UfCP inhalation (51.7 nm, 507 μg/m3, and ii an in-vitro model with primary rat alveolar macrophages (AM incubated with UfCP (10 μg/1 x 106 cells/ml for 1 h. Lungs and AM were analysed for pro- and anti-inflammatory lipid mediators, namely leukotriene B4 (LTB4, prostaglandin E2 (PGE2, 15(S-hydroxy-eicosatetraenoic acid (15(S-HETE, lipoxin A4 (LXA4 and oxidative stress marker 8-isoprostane by enzyme immunoassays and immunohistochemistry. Results In non-sensitized mice UfCP exposure induced a light non-significant increase of all lipid mediators. Similarly but significantly in rat AM all lipid mediators were induced already within 1 h of UfCP stimulation. Also sensitized and challenge mice exposed to filtered air showed a partially significant increase in all lipid mediators. In sensitized and challenged mice UfCP exposure induced highest significant levels of all lipid mediators in the lungs together with the peak of allergic airway inflammation on day 7 after UfCP inhalation. The levels of LTB4, 8-isoprostane and PGE2 were

  11. Evaluation of particle growth systems for sampling and analysis of atmospheric fine particles

    Institute of Scientific and Technical Information of China (English)

    Dae Seong Kim; Sang Bum Hong; Jung-Taek Kwon; Kihong Park

    2011-01-01

    Three types of water-based condensational growth systems,which can enable particles to grow in size to facilitate sampling and subsequent chemical analysis,were evaluated.The first one is a mixing type growth system where aerosols are mixed with saturated water vapor,the second one is a thermal diffusive growth system where warm flow enters cold-walled tube,and the third one is a laminar flow type where cold flow enters a warm wet-wall tube.Hygroscopic sodium chloride (NaCl),ammonium sulfate ((NH4)2SO4) and ammonium nitrate (NH4NO3),and non-hygroscopic polystyrene latex (PSL) particles,in the size range of 50-400 nm,were used to determine their growth factors through the growth systems.Our data showed that the third-type growth system could enable particles to grow most efficiently regardless of their hygroscopic property.Collection efficiency of particles in the size range of 0.05-2.5 μm,in a continuous aerosol sampler after they passed through the third-type growth system was about 100%,suggesting that the third-type growth system would be the most useful among the tested growth systems for sampling and subsequent chemical analysis of fine and ultrafine particles.

  12. Hydrostatic Hamiltonian particle-mesh (HPM) methods for atmospheric modelling

    NARCIS (Netherlands)

    Shin, S.; Reich, S.; Frank, J.E.

    2011-01-01

    We develop a hydrostatic Hamiltonian particle-mesh (HPM) method for efficient long-term numerical integration of the atmosphere. In the HPM method, the hydrostatic approximation is interpreted as a holonomic constraint for the vertical position of particles. This can be viewed as defining a set of v

  13. Size-Resolved Ultrafine Particle Deposition and Brownian Coagulation from Gasoline Vehicle Exhaust in an Environmental Test Chamber.

    Science.gov (United States)

    Zhao, Yu; Wang, Fang; Zhao, Jianing

    2015-10-20

    Size-resolved deposition rates and Brownian coagulation of particles between 20 and 900 nm (mobility diameter) were estimated in a well-mixed environmental chamber from a gasoline vehicle exhaust with a total peak particle concentration of 10(5)-10(6) particles/cm(3) at 12.24-25.22 °C. A deposition theory with modified friction velocity and coagulation model was also employed to predict particle concentration decay. Initially during particle decay, approximately 85% or more of the particles had diameters of vehicle exhaust particle dynamics and assess human exposure to vehicle particle pollutants in urban areas, tunnels, and underground parking lots.

  14. Impact of particle formation on atmospheric ions and particle number concentrations in an urban environment

    Science.gov (United States)

    Cheung, H. C.; Chou, C. C.-K.; Jayaratne, E. R.; Morawska, L.

    2015-04-01

    A measurement campaign was conducted from 3 to 19 December 2012 at an urban site of Brisbane, Australia. Size distribution of ions and particle number concentrations were measured to investigate the influence of particle formation and biomass burning on atmospheric ion and particle concentrations. Overall ion and particle number concentrations during the measurement period were found to be (- 1.2 × 103 cm- 3 | + 1.6 × 103 cm- 3) and 4.4 × 103, respectively. The results of correlation analysis between concentrations of ions and nitrogen oxides indicated that positive and negative ions originated from similar sources, and that vehicle exhaust emissions had a more significant influence on intermediate/large ions, while cluster ions rapidly attached to larger particles once emitted into the atmosphere. Diurnal variations in ion concentration suggested the enrichment of intermediate and large ions on new particle formation event days, indicating that they were involved in the particle formation processes. Elevated total ions, particularly larger ions, and particle number concentrations were found during biomass burning episodes. This could be due to the attachment of cluster ions onto accumulation mode particles or production of charged particles from biomass burning, which were in turn transported to the measurement site. The results of this work enhance scientific understanding of the sources of atmospheric ions in an urban environment, as well as their interactions with particles during particle formation processes.

  15. Human peripheral blood mononuclear cells (PBMCs) from smokers release higher levels of IL-1-like cytokines after exposure to combustion-generated ultrafine particles

    Science.gov (United States)

    De Falco, Gianluigi; Terlizzi, Michela; Sirignano, Mariano; Commodo, Mario; D’Anna, Andrea; Aquino, Rita P.; Pinto, Aldo; Sorrentino, Rosalinda

    2017-01-01

    Ultrafine particles (UFP) generated by combustion processes are often associated with adverse health effects. However, little is known about the inflammatory processes generated by UFP that may underlie their toxicological activity. Murine macrophages (J774.1 cells) and human peripheral blood mononuclear cells (PBMCs) were used to evaluate the molecular mechanism underlying the pro-inflammatory activity of UFP. The addition of soot particles to J774.1 cells induced a concentration-dependent release of IL-1α, IL-1β and IL-33 This effect was not associated with cell death and, in contrast to literature, was pronounced at very low concentrations (5–100 pg/ml). Similarly, UFP induced the release of IL-1α, IL-18 and IL-33 by PBMCs. However, this effect was solely observed in PBMCs obtained from smokers, as the PBMCs from non-smokers instead released higher levels of IL-10. The release of these cytokines after UFP exposure was caspase-1- and NLRP3 inflammasome-dependent in PBMCs from healthy smokers, whereas IL-1α release was calpain-dependent. These results show that UFP at very low concentrations are able to give rise to an inflammatory process that is responsible for IL-1α, IL-18 and IL-33 release, which is pronounced in PBMCs from smokers, confirming that these individuals are especially susceptible to inflammatory-based airway diseases once exposed to air pollution. PMID:28223692

  16. Preparation of Ultra-fine Aluminum Nitride in Thermal Plasma

    Institute of Scientific and Technical Information of China (English)

    漆继红; 罗义文; 印永祥; 代晓雁

    2002-01-01

    Ultra-fine aluminum nitride has been synthesized by the evaporation of aluminum powder at atmospheric-pressure nitrogen plasma in a hot-wall reactor. The average size of aluminum nitride particle is 0.11μm measured by scanning electric mirror (SEM), and the purity is at least over 90% evaluated by X-Ray diffraction (XRD). The conversion of Al powder to aluminum nitride is strongly depended on the injection of NH3. Typical experimental parameters such as the feed rate of raw material, the flow rate of ammonia and the position of injecting aluminum powder into the reactor are given.

  17. Estimate Total Number of the Earth Atmospheric Particle with Standard Atmosphere Model

    Institute of Scientific and Technical Information of China (English)

    GAO Chong-Yi

    2001-01-01

    The total number of atmospheric particle (AP) is an important datum for planetary science and geoscience.Estimating entire AP number is also a familiar question in general physics.With standard atmosphere model,considering the number difference of AP caused by rough and uneven in the earth surface below,the sum of dry clean atmosphere particle is 1.06962 × 1044.So the whole number of AP including water vapor is 1.0740 × 1044.The rough estimation for the total number of AP on other planets (or satellites) in condensed state is also discussed on the base of it.

  18. Comparison of carcinogen, carbon monoxide, and ultrafine particle emissions from narghile waterpipe and cigarette smoking: Sidestream smoke measurements and assessment of second-hand smoke emission factors

    Science.gov (United States)

    Daher, Nancy; Saleh, Rawad; Jaroudi, Ezzat; Sheheitli, Hiba; Badr, Thérèse; Sepetdjian, Elizabeth; Al Rashidi, Mariam; Saliba, Najat; Shihadeh, Alan

    2010-01-01

    The lack of scientific evidence on the constituents, properties, and health effects of second-hand waterpipe smoke has fueled controversy over whether public smoking bans should include the waterpipe. The purpose of this study was to investigate and compare emissions of ultrafine particles (UFP, carcinogenic polyaromatic hydrocarbons (PAH), volatile aldehydes, and carbon monoxide (CO) for cigarettes and narghile (shisha, hookah) waterpipes. These smoke constituents are associated with a variety of cancers, and heart and pulmonary diseases, and span the volatility range found in tobacco smoke. Sidestream cigarette and waterpipe smoke was captured and aged in a 1 m 3 Teflon-coated chamber operating at 1.5 air changes per hour (ACH). The chamber was characterized for particle mass and number surface deposition rates. UFP and CO concentrations were measured online using a fast particle spectrometer (TSI 3090 Engine Exhaust Particle Sizer), and an indoor air quality monitor. Particulate PAH and gaseous volatile aldehydes were captured on glass fiber filters and DNPH-coated SPE cartridges, respectively, and analyzed off-line using GC-MS and HPLC-MS. PAH compounds quantified were the 5- and 6-ring compounds of the EPA priority list. Measured aldehydes consisted of formaldehyde, acetaldehyde, acrolein, methacrolein, and propionaldehyde. We found that a single waterpipe use session emits in the sidestream smoke approximately four times the carcinogenic PAH, four times the volatile aldehydes, and 30 times the CO of a single cigarette. Accounting for exhaled mainstream smoke, and given a habitual smoker smoking rate of 2 cigarettes per hour, during a typical one-hour waterpipe use session a waterpipe smoker likely generates ambient carcinogens and toxicants equivalent to 2-10 cigarette smokers, depending on the compound in question. There is therefore good reason to include waterpipe tobacco smoking in public smoking bans.

  19. Power Spectral Densities of Atmospheric Aerosol Particle Counts

    Science.gov (United States)

    2010-01-01

    directly by absorbing and scattering radiation and indirectly by acting as cloud condensation nuclei (CCN). They are also important in atmospheric...are generated photochemically from vapor-phase terpenes emitted by plants; and combustion-generated particles from vehicular traffic, biomass

  20. Hygroscopic properties of ultrafine aerosol particles in the boreal forest: diurnal variation, solubility and the influence of sulfuric acid

    Directory of Open Access Journals (Sweden)

    M. Ehn

    2007-01-01

    Full Text Available The hygroscopic growth of aerosol particles present in a boreal forest was measured at a relative humidity of 88%. Simultaneously the gas phase concentration of sulfuric acid, a very hygroscopic compound, was monitored. The focus was mainly on days with new particle formation by nucleation. The measured hygroscopic growth factors (GF correlated positively with the gaseous phase sulfuric acid concentrations. The smaller the particles, the stronger the correlation, with r=0.20 for 50 nm and r=0.50 for 10 nm particles. The increase in GF due to condensing sulfuric acid is expected to be larger for particles with initially smaller masses. During new particle formation, the changes in solubility of the new particles were calculated during their growth to Aitken mode sizes. As the modal diameter increased, the solubility of the particles decreased. This indicated that the initial particle growth was due to more hygroscopic compounds, whereas the later growth during the evening and night was mainly caused by less hygroscopic or even hydrophobic compounds. For all the measured sizes, a diurnal variation in GF was observed both during days with and without particle formation. The GF was lowest at around midnight, with a mean value of 1.12–1.24 depending on particle size and if new particle formation occurred during the day, and increased to 1.25–1.34 around noon. This can be tentatively explained by day- and nighttime gas-phase chemistry; different vapors will be present depending on the time of day, and through condensation these compounds will alter the hygroscopic properties of the particles in different ways.

  1. Ultrafine particles derived from mineral processing: A case study of the Pb-Zn sulfide ore with emphasis on lead-bearing colloids.

    Science.gov (United States)

    Mikhlin, Yuri; Vorobyev, Sergey; Romanchenko, Alexander; Karasev, Sergey; Karacharov, Anton; Zharkov, Sergey

    2016-03-01

    Although mining and mineral processing industry is a vast source of heavy metal pollutants, the formation and behavior of micrometer- and nanometer-sized particles and their aqueous colloids entered the environment from the technological media has received insufficient attention to date. Here, the yield and characteristics of ultrafine mineral entities produced by routine grinding of the Pb-Zn sulfide ore (Gorevskoe ore deposit, Russia) were studied using laser diffraction analysis (LDA), dynamic light scattering (DLS) and zeta potential measurement, microscopy, X-ray photoelectron spectroscopy, with most attention given to toxic lead species. It was revealed, in particular, that the fraction of particles less that 1 μm in the ground ore typical reaches 0.4 vol. %. The aquatic particles in supernatants were micrometer size aggregates with increased content of zinc, sulfur, calcium as compared with the bulk ore concentrations. The hydrodynamic diameter of the colloidal species decreased with time, with their zeta potentials remaining about -12 mV. The colloids produced from galena were composed of 20-50 nm PbS nanoparticles associated with lead sulfate and thiosulfate, while the surface oxidation products at precipitated galena were largely lead oxyhydroxides. The size and zeta potential of the lead-bearing colloids decreased with time down to about 100 nm and from -15 mV to -30 mV, respectively. And, conversely, lead sulfide nanoparticles were mobilized before the aggregates during redispersion of the precipitates in fresh portions of water. The potential environmental impact of the metal-bearing colloids, which is due to the large-scale production and relative stability, is discussed.

  2. Ionisation of the terrestrial atmosphere caused by energetic particles

    Energy Technology Data Exchange (ETDEWEB)

    Heber, Bernd; Herbst, Klaudia [Christian-Albrechts-Universitaet Kiel (Germany); Fichtner, Horst; Scherer, Klaus [Ruhr-Universitaet Bochum (Germany)

    2008-07-01

    Solar energetic particle (SEP) events are known to cause changes in constituents of the Earth's polar neutral middle atmosphere. During the past years several large SEP events have been observed to generate such atmospheric variations. Furthermore, Galactic Cosmic Rays (GCRs)are known to be the principal agents of ionization in the atmosphere above certain altitudes. A combination of derivatives of the GEANT 4 code, MAGNETOCOSMICS and PLANETOCOSMICS, allows to compute the GCR produced particle fluxes as well as the level of ionization at different altitudes and geographic/geomagnetic locations. In order to determine the accuracy of our model, we compare our results with balloon measurements of the ion pair production over Palestine, Texas, in 1969 and 1970. In this contribution we present results from our investigation of the ionization rate above 50 km in response to different levels of solar modulation of GCRs and compare the effect of the latter with that of large SEP events.

  3. Particle precipitation: How the spectrum fit impacts atmospheric chemistry

    Science.gov (United States)

    Wissing, J. M.; Nieder, H.; Yakovchouk, O. S.; Sinnhuber, M.

    2016-11-01

    Particle precipitation causes atmospheric ionization. Modeled ionization rates are widely used in atmospheric chemistry/climate simulations of the upper atmosphere. As ionization rates are based on particle measurements some assumptions concerning the energy spectrum are required. While detectors measure particles binned into certain energy ranges only, the calculation of a ionization profile needs a fit for the whole energy spectrum. Therefore the following assumptions are needed: (a) fit function (e.g. power-law or Maxwellian), (b) energy range, (c) amount of segments in the spectral fit, (d) fixed or variable positions of intersections between these segments. The aim of this paper is to quantify the impact of different assumptions on ionization rates as well as their consequences for atmospheric chemistry modeling. As the assumptions about the particle spectrum are independent from the ionization model itself the results of this paper are not restricted to a single ionization model, even though the Atmospheric Ionization Module OSnabrück (AIMOS, Wissing and Kallenrode, 2009) is used here. We include protons only as this allows us to trace changes in the chemistry model directly back to the different assumptions without the need to interpret superposed ionization profiles. However, since every particle species requires a particle spectrum fit with the mentioned assumptions the results are generally applicable to all precipitating particles. The reader may argue that the selection of assumptions of the particle fit is of minor interest, but we would like to emphasize on this topic as it is a major, if not the main, source of discrepancies between different ionization models (and reality). Depending on the assumptions single ionization profiles may vary by a factor of 5, long-term calculations may show systematic over- or underestimation in specific altitudes and even for ideal setups the definition of the energy-range involves an intrinsic 25% uncertainty for the

  4. Ultrafine particles from diesel vehicle emissions at different driving cycles induce differential vascular pro-inflammatory responses: Implication of chemical components and NF-κB signaling

    Directory of Open Access Journals (Sweden)

    Jen Nelson

    2010-03-01

    Full Text Available Abstract Background Epidemiological evidence supports the association between exposure to ambient particulate matter (PM and cardiovascular diseases. Chronic exposure to ultrafine particles (UFP; Dp Results UFP2 contained a higher level of redox active organic compounds and metals on a per PM mass basis than UFP1. While both UFP1 and UFP2 induced superoxide production and up-regulated stress response genes such as heme oxygenease-1 (HO-1, OKL38, and tissue factor (TF, only UFP2 induced the expression of pro-inflammatory genes such as IL-8 (2.8 ± 0.3-fold, MCP-1 (3.9 ± 0.4-fold, and VCAM (6.5 ± 1.1-fold (n = 3, P P Conclusion While UFP1 induced higher level of oxidative stress and stress response gene expression, only UFP2, with higher levels of redox active organic compounds and metals, induced pro-inflammatory responses via NF-κB signaling. Thus, UFP with distinct chemical compositions caused differential response patterns in endothelial cells.

  5. A land use regression model for ambient ultrafine particles in Montreal, Canada: A comparison of linear regression and a machine learning approach.

    Science.gov (United States)

    Weichenthal, Scott; Ryswyk, Keith Van; Goldstein, Alon; Bagg, Scott; Shekkarizfard, Maryam; Hatzopoulou, Marianne

    2016-04-01

    Existing evidence suggests that ambient ultrafine particles (UFPs) (regression model for UFPs in Montreal, Canada using mobile monitoring data collected from 414 road segments during the summer and winter months between 2011 and 2012. Two different approaches were examined for model development including standard multivariable linear regression and a machine learning approach (kernel-based regularized least squares (KRLS)) that learns the functional form of covariate impacts on ambient UFP concentrations from the data. The final models included parameters for population density, ambient temperature and wind speed, land use parameters (park space and open space), length of local roads and rail, and estimated annual average NOx emissions from traffic. The final multivariable linear regression model explained 62% of the spatial variation in ambient UFP concentrations whereas the KRLS model explained 79% of the variance. The KRLS model performed slightly better than the linear regression model when evaluated using an external dataset (R(2)=0.58 vs. 0.55) or a cross-validation procedure (R(2)=0.67 vs. 0.60). In general, our findings suggest that the KRLS approach may offer modest improvements in predictive performance compared to standard multivariable linear regression models used to estimate spatial variations in ambient UFPs. However, differences in predictive performance were not statistically significant when evaluated using the cross-validation procedure.

  6. Health risks caused by short term exposure to ultrafine particles generated by residential wood combustion: a case study of Temuco, Chile.

    Science.gov (United States)

    Díaz-Robles, Luis A; Fu, Joshua S; Vergara-Fernández, Alberto; Etcharren, Pablo; Schiappacasse, Luis N; Reed, Gregory D; Silva, María P

    2014-05-01

    Temuco is one of the most highly wood smoke polluted cities in Chile; however, there is scarce evidence of respiratory morbidity due to fine particulate matter. We aimed to estimate the relationship between daily concentration of ultrafine particles (UFP), with an aerodynamic diameter ≤ 0.1 μm, and outpatient visits for respiratory illness at medical care centers of Temuco, Chile, from August the 20th, 2009 to June the 30th, 2011. The Air Pollution Health Effects European Approach (APHEA2) protocol was followed, and a multivariate semi-parametric Poisson regression model was fitted with GAM techniques using R-Project statistical package; controlling for trend, seasonality, and confounders. The daily UFP were measured by a MOUDI NR-110 sampler. We found that results of the statistical analyses show significant associations between UFP and respiratory outpatient visits, with the elderly (population ≥ 65 years), being the group that presented the greatest risk. An interquartile increase of 4.73 μg/m(3) in UFP (lag 5 days) was associated with respiratory outpatient visits with a relative risk (RR) of 1.1458 [95% CI (1.0497-1.2507)] for the elderly. These results show novel findings regarding the relevance of daily UFP concentrations and health risk, especially for susceptible population in a wood smoke polluted city.

  7. Heterogeneities in inflammatory and cytotoxic responses of RAW 264.7 macrophage cell line to urban air coarse, fine, and ultrafine particles from six European sampling campaigns

    Energy Technology Data Exchange (ETDEWEB)

    Jalava, P.I.; Salonen, R.O.; Pennanen, A.S.; Sillanpaa, M.; Halinen, A.I.; Happo, M.S.; Hillamo, R.; Brunekreef, B.; Katsouyanni, K.; Sunyer, J.; Hirvonen, M.R. [National Public Health Institute, Kuopio (Finland). Dept. for Environmental Health

    2007-03-15

    We investigated the cytotoxic and inflammatory activities of size-segregated particulate samples (particulate matter, PM) from contrasting air pollution situations in Europe. Coarse (PM10-2.5), fine (PM2.5-0.2), and ultrafine (PM0.2) particulate samples were collected with a modified Harvard high-volume cascade impactor (HVCI). Mouse RAW 264.7 macrophages were exposed to the samples for 24 h. Selected inflammatory mediators, nitric oxide (NO) and cytokines (tumor necrosis factor alpha (TNF alpha), interleukin 6 (IL-6), macrophage inflammatory protein-2 (MIP-2)), were measured together with cytotoxicity (MTT test), and analysis of apoptosis and cell cycle (propidium iodide staining). The PM10-2.5 samples had a much higher inflammatory activity than the PM2.5-0.2 and PM0.2 samples, but the PM2.5-0.2 samples showed the largest differences in inflammatory activity, and the PM0.2 samples in cytotoxicity, between the sampling campaigns. The PM2.5-0.2 samples from traffic environments in springtime Barcelona and summertime Athens had the highest inflammatory activities, which may be related to the high photochemical activity in the atmosphere during the sampling campaigns. The PM0.2 sample from wintertime Prague with proven impacts from local coal and biomass combustion had very high cytotoxic and apoptotic activities and caused a distinct cell cycle arrest. Thus, particulate size, sources, and atmospheric transformation processes affect the toxicity profile of urban air particulate matter. These factors may explain some of the heterogeneity observed in particulate exposure-response relationships of human health effects in epidemiological studies.

  8. Global atmospheric particle formation from CERN CLOUD measurements

    Science.gov (United States)

    Dunne, Eimear M.; Gordon, Hamish; Kürten, Andreas; Almeida, João; Duplissy, Jonathan; Williamson, Christina; Ortega, Ismael K.; Pringle, Kirsty J.; Adamov, Alexey; Baltensperger, Urs; Barmet, Peter; Benduhn, Francois; Bianchi, Federico; Breitenlechner, Martin; Clarke, Antony; Curtius, Joachim; Dommen, Josef; Donahue, Neil M.; Ehrhart, Sebastian; Flagan, Richard C.; Franchin, Alessandro; Guida, Roberto; Hakala, Jani; Hansel, Armin; Heinritzi, Martin; Jokinen, Tuija; Kangasluoma, Juha; Kirkby, Jasper; Kulmala, Markku; Kupc, Agnieszka; Lawler, Michael J.; Lehtipalo, Katrianne; Makhmutov, Vladimir; Mann, Graham; Mathot, Serge; Merikanto, Joonas; Miettinen, Pasi; Nenes, Athanasios; Onnela, Antti; Rap, Alexandru; Reddington, Carly L. S.; Riccobono, Francesco; Richards, Nigel A. D.; Rissanen, Matti P.; Rondo, Linda; Sarnela, Nina; Schobesberger, Siegfried; Sengupta, Kamalika; Simon, Mario; Sipilä, Mikko; Smith, James N.; Stozkhov, Yuri; Tomé, Antonio; Tröstl, Jasmin; Wagner, Paul E.; Wimmer, Daniela; Winkler, Paul M.; Worsnop, Douglas R.; Carslaw, Kenneth S.

    2016-12-01

    Fundamental questions remain about the origin of newly formed atmospheric aerosol particles because data from laboratory measurements have been insufficient to build global models. In contrast, gas-phase chemistry models have been based on laboratory kinetics measurements for decades. We built a global model of aerosol formation by using extensive laboratory measurements of rates of nucleation involving sulfuric acid, ammonia, ions, and organic compounds conducted in the CERN CLOUD (Cosmics Leaving Outdoor Droplets) chamber. The simulations and a comparison with atmospheric observations show that nearly all nucleation throughout the present-day atmosphere involves ammonia or biogenic organic compounds, in addition to sulfuric acid. A considerable fraction of nucleation involves ions, but the relatively weak dependence on ion concentrations indicates that for the processes studied, variations in cosmic ray intensity do not appreciably affect climate through nucleation in the present-day atmosphere.

  9. Carbonaceous particles in the atmosphere: A historical perspective to the Fifth International Conference on Carbonaceous Particles in the Atmosphere

    Science.gov (United States)

    Penner, Joyce E.; Novakov, T.

    1996-08-01

    Carbonaceous aerosol species together with sulfates, other water-soluble inorganic compounds, and mineral particles play an important role in a variety of environmental effects. Carbonaceous particles contribute to the extinction of visible light by both scattering and absorption, thus influencing visibility degradation and radiative transfer through the atmosphere. These particles may serve as sites for condensation of water vapor and organic compounds. Components of carbonaceous material may contribute to atmospheric chemical processes because of their chemical and catalytic properties. Many of the original results in this field of research were first presented at the International Conferences on Carbonaceous Particles in the Atmosphere held in Berkeley (1978 and 1987) and in Linz and Vienna, Austria (1983 and 1991, respectively). At the fifth conference, August 23-26, 1994, at Lawrence Berkeley Laboratory, 85 papers were presented. This volume contains papers accepted for publication after peer review. In this introduction we attempt to provide an overview of research on carbonaceous particles from the 1950s to mid-1970s, which provided the backdrop for the first conference. We follow this by outlining research accomplishments and evolution of emphasis (as evidenced by the material presented at these conferences) and by summarizing the present state of this field of research.

  10. The formation of ultra-fine particles during ozone-initiated oxidations with terpenes emitted from natural paint

    Energy Technology Data Exchange (ETDEWEB)

    Lamorena, Rheo B. [Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, 373-1 Guseong-Dong, Yuseong-Gu, Daejeon 305-701 (Korea, Republic of); Jung, Sang-Guen [Environment and Process Technology Division, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650 (Korea, Republic of); Bae, Gwi-Nam [Environment and Process Technology Division, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650 (Korea, Republic of); Lee, Woojin [Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, 373-1 Guseong-Dong, Yuseong-Gu, Daejeon 305-701 (Korea, Republic of)]. E-mail: woojin_lee@kaist.ac.kr

    2007-03-06

    The formation of secondary products during the ozone-initiated oxidations with biogenic VOCs emitted from natural paint was investigated in this study. Mass spectrometry and infrared spectroscopy measurements have shown that the major components of gas-phase chemicals emitted from natural paint are monoterpenes including {alpha}- and {beta}-pinenes, camphene, p-cymene, and limonene. A significant formation of gaseous carbonyl products and nano-sized particles (4.4-168 nm) was observed in the presence of ozone. Carboxylic acids were also observed to form during the reactions (i.e. formic acid at 0.170 ppm and acetic acid at 0.260 ppm). The formation of particles increased as the volume of paint introduced into a reaction chamber increased. A secondary increase in the particle number concentration was observed after 440 min, which suggests further partitioning of oxidation products (i.e. carboxylic acids) into the particles previously existing in the reaction chamber. The growth of particles increased as the mean particle diameter and particle mass concentrations increased during the reaction. The experimental results obtained in this study may provide insight into the potential exposure of occupants to irritating chemical compounds formed during the oxidations of biogenic VOCs emitted from natural paint in indoor environments.

  11. Solar energetic particle interactions with the Venusian atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Plainaki, Christina; Grassi, Davide [INAF-IAPS, Rome (Italy); Paschalis, Pavlos; Mavromichalaki, Helen [National and Kapodistrian Univ., Athens (Greece). Nuclear and Particle Physics Dept.; Andriopoulou, Maria [Austrian Academy of Sciences, Graz (Austria). Space Research Science Inst.

    2016-11-01

    In the context of planetary space weather, we estimate the ion production rates in the Venusian atmosphere due to the interactions of solar energetic particles (SEPs) with gas. The assumed concept for our estimations is based on two cases of SEP events, previously observed in near-Earth space: the event in October 1989 and the event in May 2012. For both cases, we assume that the directional properties of the flux and the interplanetary magnetic field configuration would have allowed the SEPs' arrival at Venus and their penetration to the planet's atmosphere. For the event in May 2012, we consider the solar particle properties (integrated flux and rigidity spectrum) obtained by the Neutron Monitor Based Anisotropic GLE Pure Power Law (NMBANGLE PPOLA) model (Plainaki et al., 2010, 2014) applied previously for the Earth case and scaled to the distance of Venus from the Sun. For the simulation of the actual cascade in the Venusian atmosphere initiated by the incoming particle fluxes, we apply the DYASTIMA code, a Monte Carlo (MC) application based on the Geant4 software (Paschalis et al., 2014). Our predictions are afterwards compared to other estimations derived from previous studies and discussed. Finally, we discuss the differences between the nominal ionization profile due to galactic cosmic-ray-atmosphere interactions and the profile during periods of intense solar activity, and we show the importance of understanding space weather conditions on Venus in the context of future mission preparation and data interpretation.

  12. Atmospheric Tar Balls: Particles from Biomass and Biofuel Burning

    Science.gov (United States)

    Posfai, Mihaly; Gelencser, Andras; Simonics, Renata; Arato, Krisztina; Li, Jia; Hobbs, Peter V.; Buseck, Peter R.

    2004-01-01

    Tar balls are amorphous, carbonaceous spherules that occur in the tropospheric aerosol as a result of biomass and biofuel burning. They form a distinct group of particles with diameters typically between 30 and 500 nm and readily identifiable with electron microscopy. Their lack of a turbostratic microstructure distinguishes them from soot, and their morphology and composition (approximately 90 mol% carbon) renders them distinct from other carbonaceous particles. Tar balls are particularly abundant in slightly aged (minutes to hours old) biomass smoke, indicating that they likely form by gas-to-particle conversion within smoke plumes. The material of tar balls is initially hygroscopic; however, the particles become largely insoluble as a result of free radical polymerization of their organic molecules. Consequently, tar balls are primarily externally mixed with other particle types, and they do not appreciably increase in size during aging. When tar balls coagulate with water-bearing particles, their material may partly dissolve and no longer be recognizable as distinct particles. Tar balls may contain organic compounds that absorb sunlight. They are an important, previously unrecognized type of carbonaceous (organic) atmospheric particle.

  13. Atmospheric tar balls: Particles from biomass and biofuel burning

    Science.gov (United States)

    Pósfai, MiháLy; GelencséR, AndráS.; Simonics, RenáTa; Arató, Krisztina; Li, Jia; Hobbs, Peter V.; Buseck, Peter R.

    2004-03-01

    "Tar balls" are amorphous, carbonaceous spherules that occur in the tropospheric aerosol as a result of biomass and biofuel burning. They form a distinct group of particles with diameters typically between 30 and 500 nm and readily identifiable with electron microscopy. Their lack of a turbostratic microstructure distinguishes them from soot, and their morphology and composition (˜90 mol % carbon) renders them distinct from other carbonaceous particles. Tar balls are particularly abundant in slightly aged (minutes to hours old) biomass smoke, indicating that they likely form by gas-to-particle conversion within smoke plumes. The material of tar balls is initially hygroscopic; however, the particles become largely insoluble as a result of free radical polymerization of their organic molecules. Consequently, tar balls are primarily externally mixed with other particle types, and they do not appreciably increase in size during aging. When tar balls coagulate with water-bearing particles, their material may partly dissolve and no longer be recognizable as distinct particles. Tar balls may contain organic compounds that absorb sunlight. They are an important, previously unrecognized type of carbonaceous (organic) atmospheric particle.

  14. Impact of aerosols and atmospheric particles on plant leaf proteins

    Science.gov (United States)

    Yan, Xing; Shi, Wen Z.; Zhao, Wen J.; Luo, Na N.

    2014-05-01

    Aerosols and atmospheric particles can diffuse and absorb solar radiation, and directly affect plant photosynthesis and related protein expression. In this study, for the first time, we performed an extensive investigation of the effects of aerosols and atmospheric particles on plant leaf proteins by combining Geographic Information System and proteomic approaches. Data on particles with diameters of 0.1-1.0 μm (PM1) from different locations across the city of Beijing and the aerosol optical depth (AOD) over the past 6 years (2007-2012) were collected. In order to make the study more reliable, we segregated the influence of soil pollution by measuring the heavy metal content. On the basis of AOD and PM1, two regions corresponding to strong and weak diffuse solar radiations were selected for analyzing the changes in the expression of plant proteins. Our results demonstrated that in areas with strong diffuse solar radiations, plant ribulose bisphosphate carboxylase was expressed at higher levels, but oxygen evolved in enhancer protein and light-harvesting complex II protein were expressed at lower levels. The expression of ATP synthase subunit beta and chlorophyll a-b binding protein were similar in both regions. By analyzing the changes in the expression of these leaf proteins and their functions, we conclude that aerosols and atmospheric particles stimulate plant photosynthesis facilitated by diffuse solar radiations.

  15. Study on Individual PAHs Content in Ultrafine Particles from Solid Fractions of Diesel and Biodiesel Exhaust Fumes

    OpenAIRE

    Małgorzata Szewczyńska; Małgorzata Pośniak; Elżbieta Dobrzyńska

    2013-01-01

    In order to characterize PAHs emissions of diesel engine fuelled with diesel and its blend (B20, B40). In the particle phase, PAHs in engine exhausts were collected by fiberglass filters using Electrical Low Pressure Impactor (ELPI) and then determined by a high performance liquid chromatography with a fluorimetric detector (HPLC-FL). The main content in exhaust gases from diesel engine, regardless the type of applied fuel, is constituted by the particles fraction of diameter

  16. Quantitative ED-EPMA of Individual Particles and its Application for Characterization of Atmospheric Aerosol Particles

    Science.gov (United States)

    Ro, C.

    2008-12-01

    An electron probe X-ray microanalysis (EPMA) technique using an energy-dispersive X-ray detector with an ultra-thin window, named low-Z particle EPMA, has been developed. The low-Z particle EPMA allows the quantitative determination of concentrations of low-Z elements such as C, N, and O, as well as higher-Z elements that can be analyzed by conventional energy-dispersive EPMA (ED-EPMA). The quantitative determination of low-Z elements (using full Monte Carlo simulations, from the electron impact to the X-ray detection) in individual environmental particles has improved the applicability of single-particle analysis, especially in atmospheric environmental aerosol research; many environmentally important atmospheric particles, e.g. sulfates, nitrates, ammonium, and carbonaceous particles, contain low-Z elements. In addition, an expert system that can perform chemical speciation from the elemental composition data obtained by the low-Z particle EPMA has been developed. The low-Z particle EPMA was applied to characterize K-feldspar particle samples of which the chemical compositions are well defined by the use of various bulk analytical methods. Chemical compositions of the K-feldspar samples obtained from the low-Z particle EPMA turn out to be very close to those from bulk analyses. The low-Z particle EPMA technique has been applied for the characterization of atmospheric aerosol particle samples, including Asian dust, urban, and indoor particulate samples: (1) The extent of chemical modification of Asian dust particles sampled in Chuncheon and Incheon, Korea, during several Asian dust storm events occurred in 2002-2006 was investigated. Mixing of Asian dust with air pollutants and sea-salts strongly depends on the characteristics of Asian dust storm events such as air-mass backward trajectories. For instance, no significant chemical modification of mineral dust corresponded to fast moving air-masses at high altitudes. Inversely, extensive chemical modification was

  17. Particle deposition in a child respiratory tract model: in vivo regional deposition of fine and ultrafine aerosols in baboons.

    Science.gov (United States)

    Albuquerque-Silva, Iolanda; Vecellio, Laurent; Durand, Marc; Avet, John; Le Pennec, Déborah; de Monte, Michèle; Montharu, Jérôme; Diot, Patrice; Cottier, Michèle; Dubois, Francis; Pourchez, Jérémie

    2014-01-01

    To relate exposure to adverse health effects, it is necessary to know where particles in the submicron range deposit in the respiratory tract. The possibly higher vulnerability of children requires specific inhalation studies. However, radio-aerosol deposition experiments involving children are rare because of ethical restrictions related to radiation exposure. Thus, an in vivo study was conducted using three baboons as a child respiratory tract model to assess regional deposition patterns (thoracic region vs. extrathoracic region) of radioactive polydisperse aerosols ([d16-d84], equal to [0.15 µm-0.5 µm], [0.25 µm-1 µm], or [1 µm-9 µm]). Results clearly demonstrated that aerosol deposition within the thoracic region and the extrathoraic region varied substantially according to particle size. High deposition in the extrathoracic region was observed for the [1 µm-9 µm] aerosol (72% ± 17%). The [0.15 µm-0.5 µm] aerosol was associated almost exclusively with thoracic region deposition (84% ± 4%). Airborne particles in the range of [0.25 µm-1 µm] showed an intermediate deposition pattern, with 49% ± 8% in the extrathoracic region and 51% ± 8% in the thoracic region. Finally, comparison of baboon and human inhalation experiments for the [1 µm-9 µm] aerosol showed similar regional deposition, leading to the conclusion that regional deposition is species-independent for this airborne particle sizes.

  18. Particle deposition in a child respiratory tract model: in vivo regional deposition of fine and ultrafine aerosols in baboons.

    Directory of Open Access Journals (Sweden)

    Iolanda Albuquerque-Silva

    Full Text Available To relate exposure to adverse health effects, it is necessary to know where particles in the submicron range deposit in the respiratory tract. The possibly higher vulnerability of children requires specific inhalation studies. However, radio-aerosol deposition experiments involving children are rare because of ethical restrictions related to radiation exposure. Thus, an in vivo study was conducted using three baboons as a child respiratory tract model to assess regional deposition patterns (thoracic region vs. extrathoracic region of radioactive polydisperse aerosols ([d16-d84], equal to [0.15 µm-0.5 µm], [0.25 µm-1 µm], or [1 µm-9 µm]. Results clearly demonstrated that aerosol deposition within the thoracic region and the extrathoraic region varied substantially according to particle size. High deposition in the extrathoracic region was observed for the [1 µm-9 µm] aerosol (72% ± 17%. The [0.15 µm-0.5 µm] aerosol was associated almost exclusively with thoracic region deposition (84% ± 4%. Airborne particles in the range of [0.25 µm-1 µm] showed an intermediate deposition pattern, with 49% ± 8% in the extrathoracic region and 51% ± 8% in the thoracic region. Finally, comparison of baboon and human inhalation experiments for the [1 µm-9 µm] aerosol showed similar regional deposition, leading to the conclusion that regional deposition is species-independent for this airborne particle sizes.

  19. Effect of nano-size nickel particles on wear resistance and high temperature oxidation resistance of ultrafine ceramic coating

    Institute of Scientific and Technical Information of China (English)

    古一; 夏长清; 李佳; 吴安如

    2004-01-01

    In order to improve the wear resistance and high temperature oxidation resistance of titanium and titanium alloy, the high temperature ultra fine ceramic coating containing nano-size nickel particles was prepared by flow coat method on the surface of industrially pure titanium TB1-0. The effects of nano-size nickel particles on the wear resistance and high temperature oxidation resistance of coating substrate system were investigated through oxidation kinetics experiment and wear resistance test. The morphologies of the specimens were examined by means of optical microscopy, scanning electron microscopy and X-ray diffraction. The results show that the high temperature ultra fine ceramic coating has notable protection effect on industrially pure titanium TB1-0 from oxidation. The oxidation and wear resistance properties of the coating can be effectively improved by adding nano-size nickel particles. The decreases from 1. 1 to 0. 6 by adding nano-size nickel particles, and the coating containing 10% (mass fraction) nano-size nickel shows the optimum properties.

  20. Experimental Study on Ultrafine Particle Removal Performance of Portable Air Cleaners with Different Filters in an Office Room

    Directory of Open Access Journals (Sweden)

    Huan Ma

    2016-01-01

    Full Text Available Size- and time-dependent aerodynamic behaviors of indoor particles, including PM1.0, were evaluated in a school office in order to test the performance of air-cleaning devices using different filters. In-situ real-time measurements were taken using an optical particle counter. The filtration characteristics of filter media, including single-pass efficiency, volume and effectiveness, were evaluated and analyzed. The electret filter (EE medium shows better initial removal efficiency than the high efficiency (HE medium in the 0.3–3.5 μm particle size range, while under the same face velocity, the filtration resistance of the HE medium is several times higher than that of the EE medium. During service life testing, the efficiency of the EE medium decreased to 60% with a total purifying air flow of 25 × 104 m3/m2. The resistance curve rose slightly before the efficiency reached the bottom, and then increased almost exponentially. The single-pass efficiency of portable air cleaner (PAC with the pre-filter (PR or the active carbon granule filter (CF was relatively poor. While PAC with the pre-filter and the high efficiency filter (PR&HE showed maximum single-pass efficiency for PM1.0 (88.6%, PAC with the HE was the most effective at removing PM1.0. The enhancement of PR with HE and electret filters augmented the single-pass efficiency, but lessened the airflow rate and effectiveness. Combined with PR, the decay constant of large-sized particles could be greater than for PACs without PR. Without regard to the lifetime, the electret filters performed better with respect to resource saving and purification improvement. A most penetrating particle size range (MPPS: 0.4–0.65 μm exists in both HE and electret filters; the MPPS tends to become larger after HE and electret filters are combined with PR. These results serve to provide a better understanding of the indoor particle removal performance of PACs when combined with different kinds of filters in

  1. Polycyclic aromatic hydrocarbons in ultrafine particles of diesel exhaust fumes – The use of ultrafast liquid chromatography

    OpenAIRE

    Małgorzata Szewczyńska; Małgorzata Pośniak

    2014-01-01

    Background: The article presents the results of the determination of polycyclic aromatic hydrocarbons (PAHs) in the fine particles fraction emitted from 3 types of diesel fuels using ultra-high pressure liquid chromatography. Material and Methods: Samples of diesel Eco, Verwa and Bio exhaust combustion fumes were generated at the model station which consisted of a diesel engine from the 2007 Diesel TDI 2.0. Personal Cascade Sioutas Impactor (PCSI) with Teflon filters was used to collect sampl...

  2. Catching Comet's Particles in the Earth's Atmosphere by Using Balloons

    Science.gov (United States)

    Potashko, Oleksandr; Viso, Michel

    The project is intended to catch cometary particles in the atmosphere by using balloons. The investigation is based upon knowledge that the Earth crosses the comet’s tails during the year. One can catch these particles at different altitudes in the atmosphere. So, we will be able to gradually advance in the ability to launch balloons from low to high altitudes and try to catch particles from different comet tails. The maximum altitude that we have to reach is 40 km. Both methods - distance observation and cometary samples from mission Stardust testify to the presence of organic components in comet’s particles. It would be useful to know more details about this organic matter for astrobiology; besides, the factor poses danger to the Earth. Moreover, it is important to prove that it is possible to get fundamental scientific results at low cost. In the last 5 years launching balloons has become popular and this movement looks like hackers’ one - as most of them occur without launch permission to airspace. The popularity of ballooning is connected with low cost of balloon, GPS unit, video recording unit. If you use iPhone, you have a light solution with GPS, video, picture and control function in one unit. The price of balloon itself begins from $50; it depends on maximum altitude, payload weight and material. Many university teams realized balloon launching and reached even stratosphere at an altitude of 33 km. But most of them take only video and picture. Meanwhile, it is possible to carry out scientific experiments by ballooning, for example to collect comet particles. There is rich experience at the moment of the use of mineral, chemical and isotopic analysis techniques and data of the comet’s dust after successful landing of StarDust capsule with samples in 2006. Besides, we may use absolutely perfect material to catch particles in the atmosphere, which was used by cosmic missions such as Stardust and Japanese Hayabusa. As to balloon launches, we could use

  3. Spatio-temporal variability and principal components of the particle number size distribution in an urban atmosphere

    Directory of Open Access Journals (Sweden)

    F. Costabile

    2008-10-01

    Full Text Available Due to the presence of diffusive anthropogenic sources in urban areas, the spatio-temporal variability of fine (diameter <1 μm and ultrafine (<0.1 μm aerosol particles has been a challenging issue in particle exposure assessment as well as atmospheric research in general. We examined number size distributions of atmospheric aerosol particles (size range 3–800 nm that were measured simultaneously at a maximum of eight observation sites in and around a city in Central Europe (Leipzig, Germany. Two main experiments were conducted with different time span and number of observation sites (2 years at 3 sites; 1 month at 8 sites. A general observation was that the particle number size distribution varied in time and space in a complex fashion as a result of interaction between local and far-range sources, and the meteorological conditions. To identify statistically independent factors in the urban aerosol, different runs of principal component analysis were conducted encompassing aerosol, gas phase, and meteorological parameters from the multiple sites. Several of the resulting principal components, outstanding with respect to their temporal persistence and spatial coverage, could be associated with aerosol particle modes: a first accumulation mode ("droplet mode", 300–800 nm, considered to be the result of liquid phase processes and far-range transport; a second accumulation mode (centered around diameters 90–250 nm, considered to result from primary emissions as well as aging through condensation and coagulation; an Aitken mode (30–200 nm linked to urban traffic emissions in addition to an urban and a rural Aitken mode; a nucleation mode (5–20 nm linked to urban traffic emissions; nucleation modes (3–20 nm linked to photochemically induced particle formation; an aged nucleation mode (10–50 nm. A number of additional components were identified to represent only local sources at a single site each, or infrequent phenomena. In summary

  4. Particle acceleration and transport in the solar atmosphere

    Science.gov (United States)

    Kontar, Eduard

    2016-07-01

    During periods of sporadic flare activity, the Sun releases energy stored in the magnetic field into the plasma of the solar atmosphere. This is an extremely efficient process, with a large fraction of the magnetic energy going into plasma particles. The solar flares are accompanied by prompt electromagnetic emission virtually over the entire electromagnetic spectrum from gamma-rays down to radio frequencies. The Sun, through its activity, also plays a driving role in the Sun-Earth system that substantially influences geophysical space. Solar flare energetic particles from the Sun are detected in interplanetary space by in-situ measurements making them a vital component of the single Sun-Earth system. Although a qualitative picture is generally agreed upon, many processes solar flare processes are poorly understood. Specifically, the processes of acceleration and propagation of energetic particles interacting on various physical scales remain major challenges in solar physics and basic plasma physics. In the talk, I will review the current understanding of solar flare energetic particles focusing on recent observational progress, which became possible due to the numerous spacecraft and ground-based observations.

  5. A marine biogenic source of atmospheric ice-nucleating particles

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, T. W.; Ladino, L. A.; Alpert, Peter A.; Breckels, M. N.; Brooks, I. M.; Browse, J.; Burrows, Susannah M.; Carslaw, K. S.; Huffman, J. A.; Judd, C.; Kilthau, W. P.; Mason, R. H.; McFiggans, Gordon; Miller, L. A.; Najera, J.; Polishchuk, E. A.; Rae, S.; Schiller, C. L.; Si, M.; Vergara Temprado, J.; Whale, Thomas; Wong, J P S; Wurl, O.; Yakobi-Hancock, J. D.; Abbatt, JPD; Aller, Josephine Y.; Bertram, Allan K.; Knopf, Daniel A.; Murray, Benjamin J.

    2015-09-09

    The formation of ice in clouds is facilitated by the presence of airborne ice nucleating particles1,2. Sea spray is one of the major global sources of atmospheric particles, but it is unclear to what extent these particles are capable of nucleating ice3–11. Here we show that material in the sea surface microlayer, which is enriched in surface active organic material representative of that found in sub-micron sea- spray aerosol12–21, nucleates ice under conditions that occur in mixed-phase clouds and high-altitude ice clouds. The ice active material is likely biogenic and is less than ~0.2 ?m in size. We also show that organic material (exudate) released by a common marine diatom nucleates ice when separated from cells and propose that organic material associated with phytoplankton cell exudates are a candidate for the observed ice nucleating ability of the microlayer samples. By combining our measurements with global model simulations of marine organic aerosol, we show that ice nucleating particles of marine origin are dominant in remote marine environments, such as the Southern Ocean, the North Pacific and the North Atlantic.

  6. Solar particle effects on minor components of the Polar atmosphere

    Directory of Open Access Journals (Sweden)

    A. Damiani

    2008-02-01

    Full Text Available Solar activity can influence the Earth's environment, and in particular the ozone layer, by direct modulation of the e.m. radiation or through variability of the incoming cosmic ray flux (solar and galactic particles. In particular, solar energetic particles (SEPs provide additional external energy to the terrestrial environment; they are able to interact with the minor constituents of the atmospheric layer and produce ionizations, dissociations, dissociative ionizations and excitations. This paper highlights the SEP effects on the chemistry of the upper atmosphere by analysing some SEP events recorded during 2005 in the descending phase of the current solar cycle. It is shown that these events can lead to short- (hours and medium- (days term ozone variations through catalytic cycles (e.g. HOx and NOx increases. We focus attention on the relationship between ozone and OH data (retrieved from MLS EOS AURA for four SEP events: 17 and 20 January, 15 May and 8 September. We confirm that SEP effects are different on the night and day hemispheres at high latitudes.

  7. Solar particle effects on minor components of the Polar atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Damiani, A. [ICES - International Center for Earth Sciences c/o Consiglio Nazionale delle Ricerche, Rome (Italy). Ist. di Acustica ' O.M. Corbino' ; INAF, Roma (Italy). Ist. di Fisica dello Spazio Interplanetario; Storini, M.; Laurenza, M. [INAF, Roma (Italy). Ist. di Fisica dello Spazio Interplanetario; Rafanelli, C. [ICES - International Center for Earth Sciences c/o Consiglio Nazionale delle Ricerche, Rome (Italy). Ist. di Acustica ' O.M. Corbino'

    2008-07-01

    Solar activity can influence the Earth's environment, and in particular the ozone layer, by direct modulation of the e.m. radiation or through variability of the incoming cosmic ray flux (solar and galactic particles). In particular, solar energetic particles (SEPs) provide additional external energy to the terrestrial environment; they are able to interact with the minor constituents of the atmospheric layer and produce ionizations, dissociations, dissociative ionizations and excitations. This paper highlights the SEP effects on the chemistry of the upper atmosphere by analysing some SEP events recorded during 2005 in the descending phase of the current solar cycle. It is shown that these events can lead to short- (hours) and medium- (days) term ozone variations through catalytic cycles (e.g. HO{sub x} and NO{sub x} increases). We focus attention on the relationship between ozone and OH data (retrieved from MLS EOS AURA) for four SEP events: 17 and 20 January, 15 May and 8 September. We confirm that SEP effects are different on the night and day hemispheres at high latitudes. (orig.)

  8. Can Highly Oxidized Organics Contribute to Atmospheric New Particle Formation?

    Science.gov (United States)

    Ortega, Ismael K; Donahue, Neil M; Kurtén, Theo; Kulmala, Markku; Focsa, Cristian; Vehkamäki, Hanna

    2016-03-10

    Highly oxidized organic molecules may play a critical role in new-particle formation within Earth's atmosphere along with sulfuric acid, which has long been considered as a key compound in this process. Here we explore the interactions of these two partners, using quantum chemistry to find the formation free energies of heterodimers and trimers as well as the fastest evaporation rates of (2,2) tetramers. We find that the heterodimers are more strongly bound than pure sulfuric acid dimers. Their stability correlates well with the oxygen to carbon ratio of the organics, their volatility, and the number of hydrogen bonds formed. Most of the stable trimers contain one sulfuric acid and two organics (1,2), whereas many (2,2) tetramers evaporate quickly, probably due to the stability of (1,2) clusters. This finding agrees with recent experimental studies that show how new-particle formation involving oxidized organics and sulfuric acid may be rate-limited by activation of (1,2) trimers, confirming the importance of this process in the atmosphere.

  9. Study on Varied Types of Ultrafine Powder Used in Refractory

    Institute of Scientific and Technical Information of China (English)

    LIXiaoming; WUQingshun

    1997-01-01

    The properties and low and medium tem-perature bonding mechanisms of varied types of SiO2 ultrafine powder used in ceramic and refractory and the temperature at which SiO2 ultrafine powder began to react with Al2O3 were studied,And initial researches on effects of ultrafine powders of Al2O3,SiC,3Al2o3·2SiO2,MgO·Al2O3 and ZrSiO4 on promoting sintering were made. The results indicated that among various types of SiO2 ultrafine powder ,non-crystal sil-ica ultrafine powder wa characterized by its structure and properties,It could yield consid-erable silica gel on its surface at low tempera-ture,which then dehydrated and formed Si-O-Si bond,thereby developing a netty structure that caused higher bond strength at low and medium temperature since the netty structure basically remperature since the netty structure basically reained as termperture rising.SiO2 ultrafine powder began to react with Al2O3 at 700℃, All of other types of ultrafine powder had effects on stimulating sintering ,but the effects were significant only when the particle size of ultrafine powder was less than 5μm。

  10. Heterogeneous reactions on the surface of fine particles in the atmosphere

    Institute of Scientific and Technical Information of China (English)

    DING Jie; ZHU Tong

    2003-01-01

    Fine particles play an important role in the atmosphere. Research on heterogeneous reactions on the surface of fine particles is one of the frontier areas of atmospheric science. In this paper, physical and chemical characteristics of fine particles in the atmosphere and the interactions between trace gases and fine particles are described, methods used in heterogeneous reactions research are discussed in detail, progress in the study of heterogeneous reactions on the surface of fine particles in the atmosphere is summarized, existing importantquestions are pointed out and future research directions are suggested.

  11. Preparation and Characterization of Plasma-Sprayed Ultrafine Chromium Oxide Coatings

    Institute of Scientific and Technical Information of China (English)

    LIN Feng; JIANG Xianliang; YU Yueguang; ZENG Keli; REN Xianjing; LI Zhenduo

    2007-01-01

    Ultrafine chromium oxide coatings were prepared by plasma spraying with ultrafine feedstock. Processing parameters of plasma spraying were optimized. Optical microscope (OM) was used to observe the microstructure of the ultrafine chromium oxide coatings. Scanning electron microscopy (SEM) was used to observe the morphology and particle size of ultrafine powder feedstock as well as to examine the microstructure of the chromium oxide coating. In addition, hardness and bonding strength of the ultrafine chromium oxide coatings were measured.The results showed that the optimized plasma spraying parameters were suitable for ultrafine chromium oxide coating and the properties and microstructure of the optimized ultrafine chromium oxide coating were superior compared to conventional chromium oxide wear resistant coatings.

  12. Effect of atmospheric electricity on dry deposition of airborne particles from atmosphere

    Science.gov (United States)

    Tammet, H.; Kimmel, V.; Israelsson, S.

    The electric mechanism of dry deposition is well known in the case of unattached radon daughter clusters that are unipolar charged and of high mobility. The problematic role of the electric forces in deposition of aerosol particles is theoretically examined by comparing the fluxes of particles carried by different deposition mechanisms in a model situation. The electric mechanism of deposition appears essential for particles of diameter 10-200 nm in conditions of low wind speed. The electric flux of fine particles can be dominant on the tips of leaves and needles even in a moderate atmospheric electric field of a few hundred V m -1 measured over the plane ground surface. The electric deposition is enhanced under thunderclouds and high voltage power lines. Strong wind suppresses the relative role of the electric deposition when compared with aerodynamic deposition. When compared with diffusion deposition the electric deposition appears less uniform: the precipitation particulate matter on the tips of leaves and especially on needles of top branches of conifer trees is much more intensive than on the ground surface and electrically shielded surfaces of plants. The knowledge of deposition geometry could improve our understanding of air pollution damage to plants.

  13. Biological particles capable of triggering ice nucleation in the atmosphere

    Science.gov (United States)

    Felgitsch, Laura; Bichler, Magdalena; Vogel, André; Häusler, Thomas; Grothe, Hinrich

    2016-04-01

    Ice-nucleating particles (INPs) have a huge impact on atmospheric processes, since they can trigger ice cloud formation. In general, ice clouds interfere with the radiation balance of planet Earth effectively at high altitudes. Since ambient matter of biological origin tends to have rather large aerodynamic diameters, it exhibits a fast sinking velocity and can only reach limited altitudes. Therefore, research focused on materials found in higher quantities in the upper atmosphere. However, recent findings indicate that the role of biological INPs has been underestimated in the past. In 2012 Pummer and colleagues found that the INPs from birch pollen can be washed off and constitute of macromolecules in the size-range of a few nanometres. With such a small diameter, they show a much longer life span in the upper atmosphere than expected. Further, Huffman and colleagues showed in 2013 a burst of biological INPs over woodlands triggered by rain events, which matches the finding of Pummer et al. well. Plants originating from the northern timberline experience harsh conditions with night frost even during the warm seasons. To prevent frost damages, those plants developed coping mechanisms. Many plant species, which are domestic in cold weather zones, exhibit ice nucleation activity. Therefore, it is important to examine those plants to understand the scale at which biological INPs can be emitted. For the presented results we focus on two types of samples: Berries and tree pollen. Both belong to plants domestic at the northern timberline. With our results we are able to show that INPs are spread vastly throughout different species. Furthermore, all those INPs show certain similarities to each other, most importantly, all of the found INPs seem to be associated to macromolecules in the nano-particulate size range. We examined the INPs from birch pollen more closely. Results indicate that proteins play a major role. Pummer, B., Bauer, H., Bernardi, J., Bleicher, S

  14. Atmospheric new particle formation: real and apparent growth of neutral and charged particles

    Directory of Open Access Journals (Sweden)

    J. Leppä

    2011-01-01

    Full Text Available In this study we have provided simple analytical formulae to estimate the growth rate of a nucleation mode due to self-coagulation and the apparent growth rate due to coagulation scavenging by larger particles. These formulae were used on a set of simulations covering a wide range of atmospheric conditions. The modal growth rates were determined from the simulation results by summing the contribution of each process, by calculating the increase rate in the count mean diameter of the mode and by following the peak concentration of the mode. The results of these three methods were compared with each other and the means used to estimate the growth rate due to self-coagulation and coagulation scavenging were found to work quite well. We also investigated the role of charged particles and electric interactions in the growth of a nucleation mode. Charged particles were found to increase the growth rate due to both self-coagulation and coagulation scavenging by a factor of ~1.5 to 2. In case of increased condensation onto charged particles, the total condensational growth rate of a nucleation mode may increase significantly in the very early steps of the growth. The analytical formulae provided by this paper were designed to provide the growth rates due to different processes from aerosol dynamic simulations, but the same principles can be used to determine the growth rates from measurement data.

  15. Atmospheric new particle formation: real and apparent growth of neutral and charged particles

    Directory of Open Access Journals (Sweden)

    J. Leppä

    2011-05-01

    Full Text Available In this study we have provided simple analytical formulae to estimate the growth rate of a nucleation mode due to self-coagulation and the apparent growth rate due to coagulation scavenging by larger particles. These formulae were used on a set of simulations covering a wide range of atmospheric conditions. The modal growth rates were determined from the simulation results by summing the contribution of each process, by calculating the increase rate in the count mean diameter of the mode and by following the peak concentration of the mode. The results of these three methods were compared with each other and the means used to estimate the growth rate due to self-coagulation and coagulation scavenging were found to give accurate values. We also investigated the role of charged particles and electric interactions in the growth of a nucleation mode. Charged particles were found to increase the growth rate due to both self-coagulation and coagulation scavenging by a factor of ~1.5 to 2. In case of increased condensation onto charged particles, the total condensational growth rate of a nucleation mode may increase significantly in the very early steps of the growth. The analytical formulae provided by this paper were designed to provide the growth rates due to different processes from aerosol dynamic simulations, but the same principles can be used to determine the growth rates from measurement data.

  16. Comparison of quartz and Teflon filters for simultaneous collection of size-separated ultrafine aerosol particles and gas-phase zero samples.

    Science.gov (United States)

    Parshintsev, Jevgeni; Ruiz-Jimenez, Jose; Petäjä, Tuukka; Hartonen, Kari; Kulmala, Markku; Riekkola, Marja-Liisa

    2011-07-01

    In this research, the two most common filter media, quartz and Teflon, were tested to obtain information about the possible adsorption of gas-phase compounds onto filters during long sample collection of atmospheric aerosols. Particles of nanometer-size for off-line chemical characterization were collected using a recently introduced differential mobility analyzer for size separation. Samples were collected at an urban site (Helsinki, SMEARIII station) during spring 2010. Sampling time was 4 to 10 days for particles 50, 40, or 30 nm in diameter. Sample air flow was 4 L/min. The sampling setup was arranged so that two samples were obtained for each sampling period almost simultaneously: one containing particles and adsorbed gas-phase compounds and one containing adsorbed gas-phase compounds only. Filters were extracted and analyzed for the presence of selected carboxylic acids, polyols, nitrogen-containing compounds, and aldehydes. The results showed that, in quartz filter samples, gas-phase adsorption may be responsible for as much as 100% of some compound masses. Whether quartz or Teflon, simultaneous collection of gas-phase zero samples is essential during the whole sampling period. The dependence of the adsorption of gas-phase compounds on vapor pressure and the effect of adsorption on the deposited aerosol layer are discussed.

  17. Fragmentation energetics of clusters relevant to atmospheric new particle formation.

    Science.gov (United States)

    Bzdek, Bryan R; DePalma, Joseph W; Ridge, Douglas P; Laskin, Julia; Johnston, Murray V

    2013-02-27

    The exact mechanisms by which small clusters form and grow in the atmosphere are poorly understood, but this process may significantly impact cloud condensation nuclei number concentrations and global climate. Sulfuric acid is the key chemical component to new particle formation (NPF), but basic species such as ammonia are also important. Few laboratory experiments address the kinetics or thermodynamics of acid and base incorporation into small clusters. This work utilizes a Fourier transform ion cyclotron resonance mass spectrometer equipped with surface-induced dissociation to investigate time- and collision-energy-resolved fragmentation of positively charged ammonium bisulfate clusters. Critical energies for dissociation are obtained from Rice-Ramsperger-Kassel-Marcus/quasi-equilibrium theory modeling of the experimental data and are compared to quantum chemical calculations of the thermodynamics of cluster dissociation. Fragmentation of ammonium bisulfate clusters occurs by two pathways: (1) a two-step pathway whereby the cluster sequentially loses ammonia followed by sulfuric acid and (2) a one-step pathway whereby the cluster loses an ammonium bisulfate molecule. Experimental critical energies for loss of an ammonia molecule and loss of an ammonium bisulfate molecule are higher than the thermodynamic values. If cluster growth is considered the reverse of cluster fragmentation, these results require the presence of an activation barrier to describe the incorporation of ammonia into small acidic clusters and suggest that kinetically (i.e., diffusion) limited growth should not be assumed. An important corollary is that models of atmospheric NPF should be revised to consider activation barriers to individual chemical steps along the growth pathway.

  18. Fragmentation Energetics of Clusters Relevant to Atmospheric New Particle Formation

    Energy Technology Data Exchange (ETDEWEB)

    Bzdek, Bryan R.; Depalma, Joseph W.; Ridge, Douglas P.; Laskin, Julia; Johnston, Murray V.

    2013-02-27

    The exact mechanisms by which small clusters form and grow in the atmosphere are poorly understood, but this process may significantly impact cloud condensation nuclei number concentrations and global climate. Sulfuric acid is the key chemical component to new particle formation, but basic species such as ammonia are also important. However, few laboratory experiments address the kinetics or thermodynamics of acid and base incorporation into small clusters. This work utilizes a Fourier transform ion cyclotron resonance mass spectrometer equipped with surface-induced dissociation (FTICR-SID) to investigate time- and collision energy-resolved fragmentation of positively charged ammonium bisulfate clusters. Critical energies for dissociation are obtained from Rice-Ramsperger-Kassel-Marcus/Quasi-Equilibrium Theory (RRKM/QET) modeling of the experimental data and are compared to quantum chemical calculations of the thermodynamics of cluster dissociation. Fragmentation of ammonium bisulfate clusters occurs by two pathways: 1) a two-step pathway whereby the cluster sequentially loses ammonia followed by sulfuric acid and 2) a one-step pathway whereby the cluster loses an ammonium bisulfate molecule. Experimental critical energies for loss of an ammonia molecule and loss of an ammonium bisulfate molecule are higher than the thermodynamic values. If cluster growth is considered the reverse of cluster fragmentation, these results require the presence of an activation barrier to describe the incorporation of ammonia into small acidic clusters and suggest that kinetically (i.e. diffusion) limited growth should not be assumed. An important corollary is that models of atmospheric NPF should be revised to consider activation barriers to individual chemical steps along the growth pathway.

  19. Mixing state of particles with secondary species by single particle aerosol mass spectrometer in an atmospheric pollution event

    Science.gov (United States)

    Xu, Lingling; Chen, Jinsheng

    2016-04-01

    Single particle aerosol mass spectrometer (SPAMS) was used to characterize size distribution, chemical composition, and mixing state of particles in an atmospheric pollution event during 20 Oct. - 5 Nov., 2015 in Xiamen, Southeast China. A total of 533,012 particle mass spectra were obtained and clustered into six groups, comprising of industry metal (4.5%), dust particles (2.6%), carbonaceous species (70.7%), K-Rich particles (20.7%), seasalt (0.6%) and other particles (0.9%). Carbonaceous species were further divided into EC (70.6%), OC (28.5%), and mixed ECOC (0.9%). There were 61.7%, 58.3%, 4.0%, and 14.6% of particles internally mixed with sulfate, nitrate, ammonium and C2H3O, respectively, indicating that these particles had undergone significant aging processing. Sulfate was preferentially mixed with carbonaceous particles, while nitrate tended to mix with metal-containing and dust particles. Compared to clear days, the fractions of EC-, metal- and dust particles remarkably increased, while the fraction of OC-containing particles decreased in pollution days. The mixing state of particles, excepted for OC-containing particles with secondary species was much stronger in pollution days than that in clear days, which revealed the significant influence of secondary particles in atmospheric pollution. The different activity of OC-containing particles might be related to their much smaller aerodynamic diameter. These results could improve our understanding of aerosol characteristics and could be helpful to further investigate the atmospheric process of particles.

  20. Heavy metal in inhalable and respirable particles in urban atmosphere

    Directory of Open Access Journals (Sweden)

    T.F. Ediagbonya

    2013-09-01

    Full Text Available Human activities in Sapele are veritable sources of particulate pollution which are exuded into the atmosphere. These activities include bush burning which is one of the pre-planting activities, transportation, gas flaring, incineration of wastes refuse disposal and the use of wood as a source of fuel. The objective of this study is to determine the concentration of the trace metal in particulate matter captured in glass fibre filter paper. High volume sampler was used to collect the respirable and inhalable suspended particulate matter at ten different sites located in Sapele, from December 2010 to April 2011. The foam and the glass fibre filter were analysed for nine (Mn, Ni, Cr, Cd, Zn, Cu, Co, Fe, and Pb respectively by Flame Atomic Absorption Spectrophotometer (FAAS. The concentration of the respirable particle ranged from 104.17 to 145.83ug/cubic meter while the inhalable concentration ranged from 166.67 to 812.50ug/cubic meter. From the analysis the element Cd was moderately enriched.

  1. Fe-Ni系列合金超细粉末的磁性和有效磁各向异性常数%The Magnetic Properties and Effective Magnetic Anisotropy of Fe-Ni Ultrafine Particles

    Institute of Scientific and Technical Information of China (English)

    许士跃; 何正明; 张正明; 汪仲诚; 陈杭德; 董传华

    2000-01-01

    Fe100 - xNix alloys of ultrafine particle with the average grain size of about 10 nm were synthesized by mechanically alloying process. The samples were investigated by X-ray diffraction and measurements of the saturation magnetization and coercivity force. Both b. c.c and f. c. c phase exist within a wide range for Fe100-x Nix, while x≤45. The effective magnetic anisotropy Ke was measured by applying the law of approach to saturation. The value of Ke decreases with an increase of Ni content. It is noticed that the strain anisotropy makes a large contribution to the magnetic anisotropy. The estimation of grain size leads to the determination of the single domain critical size and domain wall energy. The exchange stiffness and exchange integral deduced from the relationship between the effective magnetic anisotropy and domain wall energy are in agreement with that calculated by other methods.

  2. Fluorocarbon coatings deposited on micron-sized particles by atmospheric PECVD

    NARCIS (Netherlands)

    Abadjieva, E.; Heijden, A.E.D.M. van der; Creyghton, Y.L.M.; Ommen, J.R. van

    2012-01-01

    Fluorocarbon coatings have been deposited on micron-sized silica particles by means of atmospheric pressure plasma-enhanced chemical vapor deposition (PECVD). The silica particles have a diameter in the range between 40 and 70 ?m. They are fluidized at atmospheric pressure in a circulating fluidized

  3. Particle concentration and flux dynamics in the atmospheric boundary layer as the indicator of formation mechanism

    Directory of Open Access Journals (Sweden)

    J. Lauros

    2010-08-01

    Full Text Available We carried out column model simulations to study particle fluxes and deposition and to evaluate different particle formation mechanisms at a boreal forest site in Finland. We show that kinetic nucleation of sulphuric acid cannot be responsible for new particle formation alone as the vertical profile of particle number distribution does not correspond to observations. Instead organic induced nucleation leads to good agreement confirming the relevance of the aerosol formation mechanism including organic compounds emitted by biosphere.

    Simulation of aerosol concentration inside the atmospheric boundary layer during nucleation days shows highly dynamical picture, where particle formation is coupled with chemistry and turbulent transport. We have demonstrated suitability of our turbulent mixing scheme in reproducing most important characteristics of particle dynamics inside the atmospheric boundary layer. Deposition and particle flux simulations show that deposition affects noticeably only the smallest particles at the lowest part of the atmospheric boundary layer.

  4. Microstructure and properties of liquid-phase sintered tungsten heavy alloys by using ultra-fine tungsten powders

    Institute of Scientific and Technical Information of China (English)

    于洋; 王尔德

    2004-01-01

    The microstructure and properties of liquid-phase sintered 93W-4.9Ni-2.1Fe tungsten heavy alloys using ultra-fine tungsten powders (medium particle size of 700 nm) and original tungsten powders (medium particle size of 3 μm) were investigated respectively. Commercial tungsten powders (original tungsten powders) were mechanically milled in a high-energy attritor mill for 35 h. Ultra-fine tungsten powders and commercial Ni, Fe powders were consolidated into green compacts by using CIP method and liquid-phase sintering at 1 465 ℃ for 30 min in the dissociated ammonia atmosphere. Liquid-phase sintered tungsten heavy alloys using ultra-fine tungsten powders exhibit full densification (above 99% in relative density) and higher strength and elongation compared with conventional liquidphase sintered alloys using original tungsten powders due to lower sintering temperature at 1 465 ℃ and short sintering time. The mechanical properties of sintered tungsten heavy alloy are found to be mainly dependent on the particles size of raw tungsten powders and liquid-phase sintering temperature.

  5. Measuring Mass-Based Hygroscopicity of Atmospheric Particles through in Situ Imaging.

    Science.gov (United States)

    Piens, Dominique S; Kelly, Stephen T; Harder, Tristan H; Petters, Markus D; O'Brien, Rachel E; Wang, Bingbing; Teske, Ken; Dowell, Pat; Laskin, Alexander; Gilles, Mary K

    2016-05-17

    Quantifying how atmospheric particles interact with water vapor is critical for understanding the effects of aerosols on climate. We present a novel method to measure the mass-based hygroscopicity of particles while characterizing their elemental and carbon functional group compositions. Since mass-based hygroscopicity is insensitive to particle geometry, it is advantageous for probing the hygroscopic behavior of atmospheric particles, which can have irregular morphologies. Combining scanning electron microscopy with energy dispersive X-ray analysis (SEM/EDX), scanning transmission X-ray microscopy (STXM) analysis, and in situ STXM humidification experiments, this method was validated using laboratory-generated, atmospherically relevant particles. Then, the hygroscopicity and elemental composition of 15 complex atmospheric particles were analyzed by leveraging quantification of C, N, and O from STXM, and complementary elemental quantification from SEM/EDX. We found three types of hygroscopic responses, and correlated high hygroscopicity with Na and Cl content. The mixing state of 158 other particles from the sample broadly agreed with those of the humidified particles, indicating the potential to infer atmospheric hygroscopic behavior from a selected subset of particles. These methods offer unique quantitative capabilities to characterize and correlate the hygroscopicity and chemistry of individual submicrometer atmospheric particles.

  6. Measuring Mass-Based Hygroscopicity of Atmospheric Particles through in situ Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Piens, Dominique` Y.; Kelly, Stephen T.; Harder, Tristan; Petters, Markus D.; O' Brien, Rachel; Wang, Bingbing; Teske, Ken; Dowell, Pat; Laskin, Alexander; Gilles, Mary K.

    2016-04-18

    Quantifying how atmospheric particles interact with water vapor is critical for understanding the effects of aerosols on climate. We present a novel method to measure the mass-based hygroscopicity of particles while characterizing their elemental and carbon functional group compositions. Since mass-based hygroscopicity is insensitive to particle geometry, it is advantageous for probing the hygroscopic behavior of atmospheric particles, which can have irregular morphologies. Combining scanning electron microscopy with energy dispersive X-ray analysis (SEM/EDX), scanning transmission X-ray microscopy (STXM) analysis, and in situ STXM humidification experiments, this method was validated using laboratory-generated, atmospherically relevant particles. Then, the hygroscopicity and elemental composition of 15 complex atmospheric particles were analyzed by leveraging quantification of C, N, and O from STXM, and complementary elemental quantification from SEM/EDX. We found three types of hygroscopic responses, and correlated high hygroscopicity with Na and Cl content. The mixing state determined for 158 particles broadly agreed with those of the humidified particles, indicating the potential to infer the atmospheric hygroscopic behavior from a selected subset of particles. These methods offer unique quantitative capabilities to characterize and correlate the hygroscopicity and chemistry of individual submicron atmospheric particles.

  7. Hydrophobic aggregation of ultrafine kaolinite

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiao-ping; HU Yue-hua; LIU Run-Qing

    2008-01-01

    The hydrophobic aggregation of ultrafine kaolinite in cationic surfactant suspension was investigated by sedimentation test, zeta potential measurement and SEM observation. SEM images reveal that kaolinite particles show the self-aggregation of edge-face in acidic media, the aggregation of edge-face and edge-edge in neutral media, and the dispersion in alkaline media due to electrostatic repulsion. In the presence of the dodecylammonium acetate cationic surfactant and in neutral and alkaline suspension, the hydrophobic aggregation of face-face is demonstrated. The zeta potential of kaolinite increases with increasing the concentration of cationic surfactant. The small and loose aggregation at a low concentration but big and tight aggregation at a high concentration is presented At pH=7 alkyl quarterly amine salt CTAB has the best hydrophobic aggregation among three cationic surfactants, namely, dodecylammonium acetate, alkyl quarterly amine salts 1227 and CTAB.

  8. [Size distributions of organic carbon (OC) and elemental carbon (EC) in Shanghai atmospheric particles].

    Science.gov (United States)

    Wang, Guang-Hua; Wei, Nan-Nan; Liu, Wei; Lin, Jun; Fan, Xue-Bo; Yao, Jian; Geng, Yan-Hong; Li, Yu-Lan; Li, Yan

    2010-09-01

    Size distributions of organic carbon (OC), elemental carbon (EC) and secondary organic carbon (SOC) in atmospheric particles with size range from 7.20 microm, collected in Jiading District, Shanghai were determined. For estimating size distribution of SOC in these atmospheric particles, a method of determining (OC/EC)(pri) in atmospheric particles with different sizes was discussed and developed, with which SOC was estimated. According to the correlation between OC and EC, main sources of the particles were also estimated roughly. The size distributions of OC and SOC showed a bi-modal with peaks in the particles with size of 3.0 microm, respectively. EC showed both of a bi-modal and tri-modal. Compared with OC, EC was preferably enriched in particles with size of particles (particles. OC and EC were preferably enriched in fine particles (particles with different sizes accounted for 15.7%-79.1% of OC in the particles with corresponding size. Concentrations of SOC in fine aerosols ( 3.00 microm) accounted for 41.4% and 43.5% of corresponding OC. Size distributions of OC, EC and SOC showed time-dependence. The correlation between OC and EC showed that the main contribution to atmospheric particles in Jiading District derived from light petrol vehicles exhaust.

  9. Charging and coagulation of radioactive and nonradioactive particles in the atmosphere

    Directory of Open Access Journals (Sweden)

    Y.-H. Kim

    2015-09-01

    Full Text Available Charging and coagulation influence one another and impact the particle charge and size distributions in the atmosphere. However, few investigations to date have focused on the coagulation kinetics of atmospheric particles accumulating charge. This study presents three approaches to include mutual effects of charging and coagulation on the microphysical evolution of atmospheric particles such as radioactive particles. The first approach employs ion balance, charge balance, and a bivariate population balance model (PBM to comprehensively calculate both charge accumulation and coagulation rates of particles. The second approach involves a much simpler description of charging, and uses a monovariate PBM and subsequent effects of charge on particle coagulation. The third approach is further simplified assuming that particles instantaneously reach their steady-state charge distributions. It is found that compared to the other two approaches, the first approach can accurately predict time-dependent changes in the size and charge distributions of particles over a wide size range covering from the free molecule to continuum regimes. The other two approaches can reliably predict both charge accumulation and coagulation rates for particles larger than about 40 nm and atmospherically relevant conditions. These approaches are applied to investigate coagulation kinetics of particles accumulating charge in a radioactive neutralizer, the urban atmosphere, and a radioactive plume. Limitations of the approaches are discussed.

  10. Investigations of gas-to-particle conversion in the atmosphere

    Science.gov (United States)

    Juozaitis, Arvydas; Trakumas, Saulius; Girgždien≐, Rasa; Girgždys, Aloyzas; Šopauskien≐, Dalia; Ulevičius, Vidmantas

    Continental aerosol particle size distributions were measured as a function of time at the] background station Aisetas and in the suburb of Vilnius. Marine aerosol particle formation was studied in outdoor photochemical chamber experiments performed on the coast of the Baltic sea. The functional dependence of the particle diameter growth rate on the particle size was calculated from the aerosol particle size distribution data and was compared with the theoretical predictions for the particle growth due to vapor condensation or due to the adsorption of aerosol precursor gases on the particle surface or within an airborne droplet. It was shown that during summer months condensation of low pressure vapors formed by gas phase homogeneous chemical reactions was predominant mechanism of the continental aerosol particle growth. While in winter growth of a submicrometer continental aerosol particle was frequently governed by two competing processes: condensation of low pressure vapors and heterogeneous oxidation of aerosol precursor gases inside the liquid droplet. Ozone was found to be an active oxidant in the heterogeneous aqueous phase chemical reactions. The outdoor photochemical chamber experiments showed that aqueous phase chemical reactions were responsible for the formation of marine sulfuric acid aerosol particles from the dimethylsulfide. After these particles were partially neutralized by ammonia to the ammonium sulfate or bisulfate, their further growth was observed to be surface limited.

  11. Oxidation Products of Biogenic Emissions Contribute to Nucleation of Atmospheric Particles

    CERN Document Server

    Riccobono, Francesco; Baltensperger, Urs; Worsnop, Douglas R; Curtius, Joachim; Carslaw, Kenneth S; Wimmer, Daniela; Wex, Heike; Weingartner, Ernest; Wagner, Paul E; Vrtala, Aron; Viisanen, Yrjö; Vaattovaara, Petri; Tsagkogeorgas, Georgios; Tomé, Antonio; Stratmann, Frank; Stozhkov, Yuri; Spracklen, Dominick V; Sipilä, Mikko; Praplan, Arnaud P; Petäjä, Tuukka; Onnela, Antti; Nieminen, Tuomo; Mathot, Serge; Makhmutov, Vladimir; Lehtipalo, Katrianne; Laaksonen, Ari; Kvashin, Alexander N.; Kürten, Andreas; Kupc, Agnieszka; Keskinen, Helmi; Kajos, Maija; Junninen, Heikki; Hansel, Armin; Franchin, Alessandro; Flagan, Richard C; Ehrhart, Sebastian; Duplissy, Jonathan; Dunne, Eimear M; Downard, Andrew; David, André; Breitenlechner, Martin; Bianchi, Federico; Amorim, Antonio; Almeida, João; Rondo, Linda; Ortega, Ismael K; Dommen, Josef; Scott, Catherine E; Vrtala, Aron; Santos, Filipe D; Schallhart, Simon; Seinfeld, John H; Sipila, Mikko; Donahue, Neil M; Kirkby, Jasper; Kulmala, Markku

    2014-01-01

    Atmospheric new-particle formation affects climate and is one of the least understood atmospheric aerosol processes. The complexity and variability of the atmosphere has hindered elucidation of the fundamental mechanism of new-particle formation from gaseous precursors. We show, in experiments performed with the CLOUD (Cosmics Leaving Outdoor Droplets) chamber at CERN, that sulfuric acid and oxidized organic vapors at atmospheric concentrations reproduce particle nucleation rates observed in the lower atmosphere. The experiments reveal a nucleation mechanism involving the formation of clusters containing sulfuric acid and oxidized organic molecules from the very first step. Inclusion of this mechanism in a global aerosol model yields a photochemically and biologically driven seasonal cycle of particle concentrations in the continental boundary layer, in good agreement with observations.

  12. Sublimation of ice particles from rocket exhausts in the upper atmosphere

    OpenAIRE

    2003-01-01

    The process of sublimation of ice particles from a rocket exhaust in the upper atmosphere is examined. Heating by solar radiation and losses of energy by means thermal radiation and sublimation are taken into account in the thermal balance of the ice particles. The time dependences of size and temperature of the ice particles are obtained. An estimation of water vapor concentration around the rocket trajectory is made. The process of sublimation of the rocket exhaust ice particles may be impo...

  13. Concentrations of PAHs in atmospheric particles (PM-10) and roadside soil particles collected in Kuala Lumpur, Malaysia

    Science.gov (United States)

    Omar, Nasr Yousef M. J.; Abas, M. Radzi Bin; Ketuly, Kamal Aziz; Tahir, Norhayati Mohd

    The concentrations of polycyclic aromatic hydrocarbons (PAHs) in atmospheric particles and roadside soil particles were measured at eight locations in the city center and the suburb of Kuala Lumpur, Malaysia. Atmospheric particles were collected using high-volume PM-10 sampler on glass fiber filters over 24 h average sampling period. Both types of samples were extracted with dichloromethane by ultrasonic agitation. The extracts were then fractionated on an alumina-silica column and the aromatic fraction was subjected to gas chromatography-mass spectrometric (GC-MS) analysis. Total PAH concentrations in the atmospheric particles and roadside soil particles were found to be 6.28±4.35 ng m -3 and 0.22±0.11 μg g -1, respectively. Benzo[ g, h, i]perylene and coronene were found to be the most abundant PAHs in airborne particles at all locations. The most abundant PAHs in the roadside soil particles were fluoranthene, pyrene and phenanthrene.

  14. The interaction between air ions and aerosol particles in the atmosphere

    CERN Document Server

    Aplin, KL

    2012-01-01

    Charged particles are continually generated in atmospheric air, and the interaction between natural ionisation and atmospheric particles is complicated. It is of some climatic importance to establish if ions are implicated in particle formation. Atmospheric ion concentrations have been investigated here at high temporal resolution, using Gerdien ion analysers at a site where synchronous meteorological measurements were also made. The background ionisation rate was also monitored with a Geiger counter, enabling ion production from natural radioactivity to be distinguished from other effects. Measurements at 1Hz offer some promise in establishing the atmospheric electrical influences in ionic nucleation bursts, although combinations of other meteorological factors are also known to be significant. High time resolution meteorological and ion measurements are therefore clearly necessary in advancing basic understanding in the behaviour of atmospheric aerosol.

  15. Secondary Cosmic Ray Particles Due to GCR Interactions in the Earth's Atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Battistoni, G.; /Milan U. /INFN, Milan; Cerutti, F.; /CERN; Fasso, A.; /SLAC; Ferrari, A.; /CERN; Garzelli, M.V.; /Milan U. /INFN, Milan; Lantz, M.; /Goteborg, ITP; Muraro, S. /Milan U. /INFN, Milan; Pinsky, L.S.; /Houston U.; Ranft, J.; /Siegen U.; Roesler, S.; /CERN; Sala, P.R.; /Milan U. /INFN, Milan

    2009-06-16

    Primary GCR interact with the Earth's atmosphere originating atmospheric showers, thus giving rise to fluxes of secondary particles in the atmosphere. Electromagnetic and hadronic interactions interplay in the production of these particles, whose detection is performed by means of complementary techniques in different energy ranges and at different depths in the atmosphere, down to the Earth's surface. Monte Carlo codes are essential calculation tools which can describe the complexity of the physics of these phenomena, thus allowing the analysis of experimental data. However, these codes are affected by important uncertainties, concerning, in particular, hadronic physics at high energy. In this paper we shall report some results concerning inclusive particle fluxes and atmospheric shower properties as obtained using the FLUKA transport and interaction code. Some emphasis will also be given to the validation of the physics models of FLUKA involved in these calculations.

  16. Molecular understanding of sulphuric acid-amine particle nucleation in the atmosphere

    CERN Document Server

    Almeida, João; Kürten, Andreas; Ortega, Ismael K; Kupiainen-Määttä, Oona; Praplan, Arnaud P; Adamov, Alexey; Amorim, Antonio; Bianchi, Federico; Breitenlechner, Martin; David, André; Dommen, Josef; Donahue, Neil M; Downard, Andrew; Dunne, Eimear; Duplissy, Jonathan; Ehrhart, Sebastian; Flagan, Richard C; Franchin, Alessandro; Guida, Roberto; Hakala, Jani; Hansel, Armin; Heinritzi, Martin; Henschel, Henning; Jokinen, Tuija; Junninen, Heikki; Kajos, Maija; Kangasluoma, Juha; Keskinen, Helmi; Kupc, Agnieszka; Kurtén, Theo; Kvashin, Alexander N; Laaksonen, Ari; Lehtipalo, Katrianne; Leiminger, Markus; Leppä, Johannes; Loukonen, Ville; Makhmutov, Vladimir; Mathot, Serge; McGrath, Matthew J; Nieminen, Tuomo; Olenius, Tinja; Onnela, Antti; Petäjä, Tuukka; Riccobono, Francesco; Riipinen, Ilona; Rissanen, Matti; Rondo, Linda; Ruuskanen, Taina; Santos, Filipe D; Sarnela, Nina; Schallhart, Simon; Schnitzhofer, Ralf; Seinfeld, John H; Simon, Mario; Sipilä, Mikko; Stozhkov, Yuri; Stratmann, Frank; Tomé, Antonio; Tröstl, Jasmin; Tsagkogeorgas, Georgios; Vaattovaara, Petri; Viisanen, Yrjo; Virtanen, Annele; Vrtala, Aron; Wagner, Paul E; Weingartner, Ernest; Wex, Heike; Williamson, Christina; Wimmer, Daniela; Ye, Penglin; Yli-Juuti, Taina; Carslaw, Kenneth S; Kulmala, Markku; Curtius, Joachim; Baltensperger, Urs; Vehkamaki, Hanna; Kirkby, Jasper

    2013-01-01

    Nucleation of aerosol particles from trace atmospheric vapours is thought to provide up to half of global cloud condensation nuclei. Aerosols can cause a net cooling of climate by scattering sunlight and by leading to smaller but more numerous cloud droplets, which makes clouds brighter and extends their lifetimes. Atmospheric aerosols derived from human activities are thought to have compensated for a large fraction of the warming caused by greenhouse gases. However, despite its importance for climate, atmospheric nucleation is poorly understood. Recently, it has been shown that sulphuric acid and ammonia cannot explain particle formation rates observed in the lower atmosphere. It is thought that amines may enhance nucleation, but until now there has been no direct evidence for amine ternary nucleation under atmospheric conditions. Here we use the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber at CERN and find that dimethylamine above three parts per trillion by volume can enhance particle formation rates ...

  17. Particle-size distribution and gas/particle partitioning of atmospheric polybrominated diphenyl ethers in urban areas of Greece

    Energy Technology Data Exchange (ETDEWEB)

    Mandalakis, Manolis; Besis, Athanasios [Environmental Chemical Processes Laboratory, Department of Chemistry, University of Crete, GR-71003 Heraklion-Voutes (Greece); Stephanou, Euripides G. [Environmental Chemical Processes Laboratory, Department of Chemistry, University of Crete, GR-71003 Heraklion-Voutes (Greece)], E-mail: stephanou@chemistry.uoc.gr

    2009-04-15

    Ambient concentrations, gas/particle partitioning and particle-size distribution of polybrominated diphenyl ethers (PBDEs) were investigated in two urban areas (Athens and Heraklion) of Greece. Atmospheric (gas + particle) concentrations of {sigma}PBDE varied from 21 to 30 pg m{sup -3} in the center of Athens and from 4 to 44 pg m{sup -3} in the suburbs of Heraklion. A predominance of particulate PBDEs was observed in Athens (71-76% in particles), whereas the opposite was evident in Heraklion (69-92% in gas phase). In both urban areas, PBDE particle-size distribution featured a distinct enrichment in smaller particles. A similar trend was also observed in aerosols of a background marine site. For all sampling sites, more than 46% of {sigma}PBDE was associated with particles of <0.57 {mu}m in diameter. Our results imply that particulate PBDEs may have long atmospheric residence time and they may be capable of reaching the deeper parts of the human respiratory system. - Analysis of size-segregated aerosol samples indicates a predominance of polybrominated diphenyl ethers in the small particle-size fraction.

  18. Study on angular variation of cosmic ray secondary particles with atmospheric depth using CORSIKA code

    Science.gov (United States)

    Patgiri, P.; Kalita, D.; Boruah, K.

    2016-08-01

    The distribution of the secondary cosmic ray charged particles in the atmosphere as a function of zenith angle of the primary particle depends on various factors such as atmospheric depth, latitude and longitude of the place of observation and possibly other atmospheric conditions. This work is focussed on the investigation of atmospheric attenuation of an Extensive Air Shower using the zenith angle distribution of the secondary charged particles, at different atmospheric depths for pure primary compositions (gamma, proton and iron nucleus) and mixed compositions employing the Monte Carlo Simulation code CORSIKA (versions 6.990 and 7.3500) in the energy range 10 TeV-1 PeV. The secondary charged particles in different zenith angle bins are fitted with a differential distribution dN sp /dθ = A(X)sinθcos n(X)θ, where the power index n(X) is a function of atmospheric depth X. For a given zenith angle θ, the frequency of the showers with secondary charged particle intensity higher than a threshold is also fitted with a relation F(θ,X0) = F(0,X0)exp[-X0(secθ - 1)/λ], where X0 is the vertical atmospheric depth and λ is the attenuation length. Further, the angular distribution parameter n(X) and attenuation co-efficients (λ) from our simulation result for different primaries are compared with available experimental data.

  19. Study on angular variation of cosmic ray secondary particles with atmospheric depth using CORSIKA code

    Science.gov (United States)

    Patgiri, P.; Kalita, D.; Boruah, K.

    2017-04-01

    The distribution of the secondary cosmic ray charged particles in the atmosphere as a function of zenith angle of the primary particle depends on various factors such as atmospheric depth, latitude and longitude of the place of observation and possibly other atmospheric conditions. This work is focussed on the investigation of atmospheric attenuation of an Extensive Air Shower using the zenith angle distribution of the secondary charged particles, at different atmospheric depths for pure primary compositions (gamma, proton and iron nucleus) and mixed compositions employing the Monte Carlo Simulation code CORSIKA (versions 6.990 and 7.3500) in the energy range 10 TeV-1 PeV. The secondary charged particles in different zenith angle bins are fitted with a differential distribution dN sp /dθ = A(X)sinθcos n(X)θ, where the power index n(X) is a function of atmospheric depth X. For a given zenith angle θ, the frequency of the showers with secondary charged particle intensity higher than a threshold is also fitted with a relation F(θ,X0) = F(0,X0)exp[-X0(secθ - 1)/λ], where X0 is the vertical atmospheric depth and λ is the attenuation length. Further, the angular distribution parameter n(X) and attenuation co-efficients (λ) from our simulation result for different primaries are compared with available experimental data.

  20. Aprovechamiento de partículas de ultrafinos de carbón de una planta lavadora en la producción de coque metalúrgico Using ultrafine particles from a coal washing plant in metallurgical coke production

    Directory of Open Access Journals (Sweden)

    Díaz Velásquez José de Jesús

    2011-05-01

    Full Text Available

    Se estudió el aprovechamiento en mezclas de ultrafinos provenientes de una planta de lavado de carbón para la producción de coque por el proceso de briquetación, utilizando 6% en peso de alquitrán de carbón como aglomerante. Se caracterizaron las materias primas y se realizó una prueba piloto de coquización en un horno tipo Koppers. Se determinó la calidad del coque por pruebas de análisis próximo, estabilidad (Micum 10, M10 y Micum 40, M40, índice de reactividad del coque al CO2 (CRI y de resistencia después de la reacción con dióxido de carbono (CSR. Los resultados mostraron que la briquetación permite obtener un coque con un CRI de 19,0% y un CSR de 75,6%, características requeridas en los procesos metalúrgicos.

    Blending ultrafine particles from a coal washing plant was studied for coke production by briquetting using 6%w coal tar as binder. The ultrafine coal particles were characterised and a pilot coking test was made in a Koppers’ furnace. Coke quality was evaluated by proximate analysis, stability (micum 10 and micum 40, coke reactivity index (CRI with CO2 and the coke’s mechanical strength after reaction with carbon dioxide (CSR index. Briquetting results showed that was possible to obtain coke having 19.0 % CRI and 75.6% CSR, these being the characteristics required in metallurgical processes.

  1. The role of ions in particle nucleation under atmospheric conditions

    DEFF Research Database (Denmark)

    Enghoff, Martin B.; Pedersen, J. O. P.; Bondo, T.

    2008-01-01

    Aerosol nucleation has been studied experimentally in purified, atmospheric air, containing trace amounts of water vapor, ozone, and sulfur dioxide. The results are compared with model calculations. It is found that an increase in ionization by a factor of 10 increases the production rate of stable...

  2. Optical properties of nonspherical atmospheric particles and relevant applications

    Directory of Open Access Journals (Sweden)

    P. Yang

    2011-09-01

    Full Text Available Recent progress in the study of the single-scattering properties of nonspherical ice crystals within cirrus clouds and nonspherical dust particles is reviewed. We have been using the finite-difference time domain (FDTD method, the discrete dipole approximation (DDA, and an improved geometric optics method (IGOM to compute the single-scattering properties of nonspherical particles. We have incorporated the so-called edge effect associated with the surface wave into the IGOM extinction and absorption efficiencies. The simulation results in the solar and thermal infrared spectral regimes are presented. Furthermore, the impacts of particle nonsphericity on downstream remote sensing implementations and radiative transfer simulations involving ice clouds and dust aerosols are also summarized.

  3. Modelling the formation of organic particles in the atmosphere

    Science.gov (United States)

    Anttila, T.; Kerminen, V.-M.; Kulmala, M.; Laaksonen, A.; O'Dowd, C.

    2003-12-01

    A modelling study investigating the formation of organic particles from inorganic, thermodynamically stable clusters was carried out. A recently-developed theory, the so-called nano-Köhler theory, which describes a thermodynamic equilibrium between a nanometer-size cluster, water and water-soluble organic compound, was implemented in a dynamical model along with a treatment of the appropriate aerosol and gas-phase processes. The obtained results suggest that both gaseous sulphuric acid and organic vapours contribute to organic particle formation. The initial growth of freshly-nucleated clusters having a diameter around 1 nm is driven by condensation of gaseous sulphuric acid and by a lesser extent cluster self-coagulation. After the clusters have reached sizes of around 2 nm in diameter, low-volatile organic vapours start to condense spontaneously into the clusters, thereby accelerating their growth to detectable sizes. A shortage of gaseous sulphuric acid or organic vapours limit, or suppress altogether, the particle formation, since freshly-nucleated clusters are rapidly coagulated away by pre-existing particles. The obtained modelling results were applied to explaining the observed seasonal cycle in the number of aerosol formation events in a continental forest site.

  4. Semi-quantitative characterisation of ambient ultrafine aerosols resulting from emissions of coal fired power stations.

    Science.gov (United States)

    Hinkley, J T; Bridgman, H A; Buhre, B J P; Gupta, R P; Nelson, P F; Wall, T F

    2008-02-25

    Emissions from coal fired power stations are known to be a significant anthropogenic source of fine atmospheric particles, both through direct primary emissions and secondary formation of sulfate and nitrate from emissions of gaseous precursors. However, there is relatively little information available in the literature regarding the contribution emissions make to the ambient aerosol, particularly in the ultrafine size range. In this study, the contribution of emissions to particles smaller than 0.3 mum in the ambient aerosol was examined at a sampling site 7 km from two large Australian coal fired power stations equipped with fabric filters. A novel approach was employed using conditional sampling based on sulfur dioxide (SO(2)) as an indicator species, and a relatively new sampler, the TSI Nanometer Aerosol Sampler. Samples were collected on transmission electron microscope (TEM) grids and examined using a combination of TEM imaging and energy dispersive X-ray (EDX) analysis for qualitative chemical analysis. The ultrafine aerosol in low SO(2) conditions was dominated by diesel soot from vehicle emissions, while significant quantities of particles, which were unstable under the electron beam, were observed in the high SO(2) samples. The behaviour of these particles was consistent with literature accounts of sulfate and nitrate species, believed to have been derived from precursor emissions from the power stations. A significant carbon peak was noted in the residues from the evaporated particles, suggesting that some secondary organic aerosol formation may also have been catalysed by these acid seed particles. No primary particulate material was observed in the minus 0.3 mum fraction. The results of this study indicate the contribution of species more commonly associated with gas to particle conversion may be more significant than expected, even close to source.

  5. Preparation of Ultra-fine Salbutamol Sulfate Particles by Reactive Precipitation and Characterization of Dry Powder Inhalant%反应沉淀法制备超细硫酸沙丁胺醇颗粒及其粉雾剂的表征

    Institute of Scientific and Technical Information of China (English)

    续京; 刘晓林; 陈建峰

    2008-01-01

    The preparation of ultra.fine particles of salbutamol sulphate(SS)was accomplished with a reactive precipitation pathway,in Which salbutamo]and sulphuric acid were used as reactants wlth the solvents of ethanol.The effects of sulphuric acid concentration.reaction temperature,stirring rate,and reaction time on the Size of the particle were investigated.A binary mixture composed of lactose and SS was prepared to evaluate SS.The results showed that ultra-fine SS particles with controlled diameters ranging between 3 grn and 0.8 μm and with a narrow distribution could be achieyed.The morphology consisting of clubbed particles was successfully obtained.The pu-fity of the particles reached above 98%with UV detection.The dose of dry powder inhalation was obtained by blending the particles with recrystallized lactose.which acted as a carrier.The deposition quantity of the drug in breathing tract was estimated using a twin impinger apparatus.Compared wlth the Shapuer powder(purchased in the market),the results showed that SS particles had more quantines subsided in simulative lung.

  6. The role of low-volatility organic compounds in initial particle growth in the atmosphere

    CERN Document Server

    Tröstl, Jasmin; Gordon, Hamish; Heinritzi, Martin; Yan, Chao; Molteni, Ugo; Ahlm, Lars; Frege, Carla; Bianchi, Federico; Wagner, Robert; Simon, Mario; Lehtipalo, Katrianne; Williamson, Christina; Craven, Jill S; Duplissy, Jonathan; Adamov, Alexey; Almeida, Joao; Bernhammer, Anne-Kathrin; Breitenlechner, Martin; Brilke, Sophia; Dias, Antònio; Ehrhart, Sebastian; Flagan, Richard C; Franchin, Alessandro; Fuchs, Claudia; Guida, Roberto; Gysel, Martin; Hansel, Armin; Hoyle, Christopher R; Jokinen, Tuija; Junninen, Heikki; Kangasluoma, Juha; Keskinen, Helmi; Kim, Jaeseok; Krapf, Manuel; Kürten, Andreas; Laaksonen, Ari; Lawler, Michael; Leiminger, Markus; Mathot, Serge; Möhler, Ottmar; Nieminen, Tuomo; Onnela, Antti; Petäjä, Tuukka; Piel, Felix M; Miettinen, Pasi; Rissanen, Matti P; Rondo, Linda; Sarnela, Nina; Schobesberger, Siegfried; Sengupta, Kamalika; Sipilä, Mikko; Smith, James; Steiner, Gerhard; Tomè, Antònio; Virtanen, Annele; Wagner, Andrea C; Weingartner, Ernest; Wimmer, Daniela; Winkler, Paul M; Ye, Penglin; Carslaw, Kenneth S; Curtius, Joachim; Dommen, Josef; Kirkby, Jasper; Kulmala, Markku; Riipinen, Ilona; Worsnop, Douglas R; Donahue, Neil M; Baltensperger, Urs

    2016-01-01

    About half of present-day cloud condensation nuclei originate from atmospheric nucleation, frequently appearing as a burst of new particles near midday. Atmospheric observations show that the growth rate of new particles often accelerates when the diameter of the particles is between one and ten nanometres. In this critical size range, new particles are most likely to be lost by coagulation with pre-existing particles, thereby failing to form new cloud condensation nuclei that are typically 50 to 100 nanometres across. Sulfuric acid vapour is often involved in nucleation but is too scarce to explain most subsequent growth, leaving organic vapours as the most plausible alternative, at least in the planetary boundary layer. Although recent studies predict that low-volatility organic vapours contribute during initial growth, direct evidence has been lacking. The accelerating growth may result from increased photolytic production of condensable organic species in the afternoon, and the presence of a possible Kelv...

  7. Microstructure of atmospheric particles revealed by TXM and a new mode of influenza virus transmission

    Energy Technology Data Exchange (ETDEWEB)

    Bao, L.M., E-mail: baoliangman@sinap.ac.cn [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Zhang, G.L., E-mail: zhangguilin@sinap.ac.cn [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Lei, Q.T.; Li, Y.; Li, X.L. [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Hwu, Y.K. [Institute of Physics, Academia Sinica, Taipei 11529, Taiwan (China); Yi, J.M. [Advanced Photon Source, Argonne National Laboratory, Argonne 60439 (United States)

    2015-09-15

    For control of influenza, firstly it is important to find the real virus transmission media. Atmospheric aerosol particles are presumably one of the media. In this study, three typical atmospheric inhaled particles in Shanghai were studied by the synchrotron based transmission X-ray microscopes (TXM). Three dimensional microstructure of the particles reveals that there are many pores contained in, particularly the coal combustion fly particles which may be possible virus carrier. The particles can transport over long distance and cause long-range infections due to its light weight. We suggest a mode which is droplet combining with aerosol mode. By this mode the transmission of global and pandemic influenzas and infection between inland avian far from population and poultry or human living in cities along coast may be explained.

  8. Comparison of analytical methods for HULIS measurements in atmospheric particles

    Directory of Open Access Journals (Sweden)

    C. Baduel

    2009-03-01

    Full Text Available Humic-Like Substances (HULIS are a major contributor to the organic carbon in atmospheric aerosol. It would be necessary to standardise an analytical method that could be easily and routinely used for HULIS measurements. We present one of the first comparisons of two of the main methods in use to extract HULIS, using i a weak anion exchanger (DEAE and ii the combination of two separation steps, one according to polarity (on C18 and the second according to acidity (with a strong anion exchanger SAX. The quantification is performed with a DOC analyzer, complemented by an investigation of the chemical structure of the extracted fractions by UV-Visible spectroscopy. The analytical performances of each method are determined and compared for humic substances standards. These methods are further applied to determine the water extractable HULIS (HULISWS and the 0.1M NaOH alkaline extractable HULIS (HULIST in atmospheric aerosol collected in an Alpine Valley during winter time. This comparison shows that the simpler DEAE isolation procedure leads to higher recoveries and better reproducibility and should therefore be recommended.

  9. Heterogeneous ice nucleation and water uptake by field-collected atmospheric particles below 273 K

    Science.gov (United States)

    Wang, Bingbing; Laskin, Alexander; Roedel, Tobias; Gilles, Mary K.; Moffet, Ryan C.; Tivanski, Alexei V.; Knopf, Daniel A.

    2012-09-01

    Ice formation induced by atmospheric particles through heterogeneous nucleation is not well understood. Onset conditions for heterogeneous ice nucleation and water uptake by particles collected in Los Angeles and Mexico City were determined as a function of temperature (200-273 K) and relative humidity with respect to ice (RHice). Four dominant particle types were identified including soot associated with organics, soot with organic and inorganics, inorganic particles of marine origin coated with organic material, and Pb/Zn-containing particles apportioned to emissions relevant to waste incineration. Single particle characterization was provided by micro-spectroscopic analyses using computer controlled scanning electron microscopy with energy dispersive analysis of X-rays (CCSEM/EDX) and scanning transmission X-ray microscopy with near edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS). Above 230 K, significant differences in onsets of water uptake and immersion freezing of different particle types were observed. Below 230 K, particles exhibited high deposition ice nucleation efficiencies and formed ice atRHicewell below homogeneous ice nucleation limits. The data suggest that water uptake and immersion freezing are more sensitive to changes in particle chemical composition compared to deposition ice nucleation. The data demonstrate that anthropogenic and marine influenced particles, exhibiting various chemical and physical properties, possess distinctly different ice nucleation efficiencies and can serve as efficient IN at atmospheric conditions typical for cirrus and mixed-phase clouds.

  10. Heterogeneous ice nucleation and water uptake by field-collected atmospheric particles below 273 K

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Bingbing; Laskin, Alexander; Roedel, Tobias R.; Gilles, Marry K.; Moffet, Ryan C.; Tivanski, Alexei V.; Knopf, Daniel A.

    2012-09-25

    Atmospheric ice formation induced by particles with complex chemical and physical properties through heterogeneous nucleation is not well understood. Heterogeneous ice nucleation and water uptake by ambient particles collected from urban environments in Los Angeles and Mexico City are presented. Using a vapour controlled cooling system equipped with an optical microscopy, the range of onset conditions for ice nucleation and water uptake by the collected particles was determined as a function of temperature (200{273 K) and relative humidity with respect to ice (RHice) up to water saturation. Three distinctly different types of authentic atmospheric particles were investigated including soot particles associated with organics/inorganics, inorganic particles of marine origin coated with organic material, and Pb/Zn containing inorganic particles apportioned to anthropogenic emissions relevant to waste incineration. Single particle characterization was provided by micro-spectroscopic analyses using computer controlled scanning electron microscopy with energy dispersive analysis of X-rays (CCSEM/EDX) and scanning transmission X-ray microscopy with near edge X-ray absorption ne structure spectroscopy (STXM/NEXAFS). Above 230 K, signicant differences in water uptake and immersion freezing effciencies of the different particle types were observed. Below 230 K, the particles exhibited high deposition ice nucleation effciencies and formed ice at RHice values well below homogeneous ice nucleation limits. The data show that the chemical composition of these eld{collected particles plays an important role in determining water uptake and immersion freezing. Heterogeneous ice nucleation rate coeffcients, cumulative ice nuclei (IN) spectrum, and IN activated fraction for deposition ice nucleation are derived. The presented ice nucleation data demonstrate that anthropogenic and marine particles comprising of various chemical and physical properties exhibit distinctly different ice

  11. Particle concentration and flux dynamics in the atmospheric boundary layer as the indicator of formation mechanism

    DEFF Research Database (Denmark)

    Lauros, J.; Sogachev, Andrey; Smolander, S.;

    2010-01-01

    profile of particle number distribution does not correspond to observations. Instead organic induced nucleation leads to good agreement confirming the relevance of the aerosol formation mechanism including organic compounds emitted by biosphere. Simulation of aerosol concentration inside the atmospheric......We carried out column model simulations to study particle fluxes and deposition and to evaluate different particle formation mechanisms at a boreal forest site in Finland. We show that kinetic nucleation of sulphuric acid cannot be responsible for new particle formation alone as the vertical...

  12. Atmospheric fate and transport of fine volcanic ash: Does particle shape matter?

    Science.gov (United States)

    White, C. M.; Allard, M. P.; Klewicki, J.; Proussevitch, A. A.; Mulukutla, G.; Genareau, K.; Sahagian, D. L.

    2013-12-01

    Volcanic ash presents hazards to infrastructure, agriculture, and human and animal health. In particular, given the economic importance of intercontinental aviation, understanding how long ash is suspended in the atmosphere, and how far it is transported has taken on greater importance. Airborne ash abrades the exteriors of aircraft, enters modern jet engines and melts while coating interior engine parts causing damage and potential failure. The time fine ash stays in the atmosphere depends on its terminal velocity. Existing models of ash terminal velocities are based on smooth, quasi-spherical particles characterized by Stokes velocity. Ash particles, however, violate the various assumptions upon which Stokes flow and associated models are based. Ash particles are non-spherical and can have complex surface and internal structure. This suggests that particle shape may be one reason that models fail to accurately predict removal rates of fine particles from volcanic ash clouds. The present research seeks to better parameterize predictive models for ash particle terminal velocities, diffusivity, and dispersion in the atmospheric boundary layer. The fundamental hypothesis being tested is that particle shape irreducibly impacts the fate and transport properties of fine volcanic ash. Pilot studies, incorporating modeling and experiments, are being conducted to test this hypothesis. Specifically, a statistical model has been developed that can account for actual volcanic ash size distributions, complex ash particle geometry, and geometry variability. Experimental results are used to systematically validate and improve the model. The experiments are being conducted at the Flow Physics Facility (FPF) at UNH. Terminal velocities and dispersion properties of fine ash are characterized using still air drop experiments in an unconstrained open space using a homogenized mix of source particles. Dispersion and sedimentation dynamics are quantified using particle image

  13. Particle-fluorescence spectrometer for real-time single-particle measurements of atmospheric organic carbon and biological aerosol.

    Science.gov (United States)

    Pan, Yong-Le; Pinnick, Ronald G; Hill, Steven C; Chang, Richard K

    2009-01-15

    A particle-fluorescence spectrometer (PFS) for real-time measurements of single-particle UV-laser-induced fluorescence (UV-LIF) excited with a pulsed (263-nm) laser is reported. The dispersed UV-LIF spectra are measured by a 32-anode PMT detector with spectral coverage from 280-600 nm. The PFS represents a significant improvement over our previous apparatus [Pinnick et al., Atmos. Environ. 2004, 38, 1657] and can (1) measure fluorescence spectra of bacterial particles having light-scattering sizes as small as 1 microm (previously limited to about 3 microm) and so can measure particles with size in the range of 1-10 microm, (2) measure each particle's elastic scattering which can be used to estimate particle size (not available previously), (3) measure single-particle fluorescence spectra with a laser and detector that can record spectra as fast as 90,000/s, although the highest rates we have found experimentally in atmospheric measurements is only several hundred per second (previously limited by detectors to only 25/s), and (4) provide a time stamp for a data block of spectra with time resolution from 10 ms to 10 min. In addition, the PFS has been modified to be more robust, transportable, and smaller. The use of an aerodynamic-focusing sheath inlet nozzle assembly has improved the sample rate. The PFS has been employed to measure UV-LIF spectra from individual atmospheric particles during October-December 2006 and January-May 2008 in New Haven, CT, and during January-May 2007 in Las Cruces, NM.

  14. Particle pair diffusion of inertial particles such as dust in the atmosphere

    Science.gov (United States)

    Malik, Nadeem; Tereda, Yoseph; Usama, Syed

    2016-04-01

    The transport of particles in turbulent flows is ubiquitous in industrial applications and also in nature such as in dust storms and pollens. The mathematical equations that describe the motion of individual inertial particles (i.e. particles with weight and friction) is not fully developed yet, although simplified descriptions in specific contexts have been proposed, such as by Maxey and Riley [1]. The relative motion of groups of particles is equally important to understand, and this can usually be related to the relative motion of two particles, or pair diffusion. In 1926 Richardson [2] proposed a pioneering theory of pair diffusion of fluid particles based upon the idea of a separation dependent pair diffusivity, K(l), where l is the distance between two particles. Richardson advanced the theory based on a locality hypothesis in which only energy in the turbulent scales similar to the pair separation l is effective in further increasing the pair separation, leading to the famous 4/3-scaling, K˜ l4/3. Recent studies in turbulent particle pair diffusion [3] has suggested that both local and non-local effects govern the pair diffusion process inside the inertial subrange in high Reynolds number turbulence containing generalised power-law energy spectra, E(k)˜ k-p with 1

  15. Mathematical modeling of atmospheric fine particle-associated primary organic compound concentrations

    Science.gov (United States)

    Rogge, Wolfgang F.; Hildemann, Lynn M.; Mazurek, Monica A.; Cass, Glen R.; Simoneit, Bernd R. T.

    1996-08-01

    An atmospheric transport model has been used to explore the relationship between source emissions and ambient air quality for individual particle phase organic compounds present in primary aerosol source emissions. An inventory of fine particulate organic compound emissions was assembled for the Los Angeles area in the year 1982. Sources characterized included noncatalyst- and catalyst-equipped autos, diesel trucks, paved road dust, tire wear, brake lining dust, meat cooking operations, industrial oil-fired boilers, roofing tar pots, natural gas combustion in residential homes, cigarette smoke, fireplaces burning oak and pine wood, and plant leaf abrasion products. These primary fine particle source emissions were supplied to a computer-based model that simulates atmospheric transport, dispersion, and dry deposition based on the time series of hourly wind observations and mixing depths. Monthly average fine particle organic compound concentrations that would prevail if the primary organic aerosol were transported without chemical reaction were computed for more than 100 organic compounds within an 80 km × 80 km modeling area centered over Los Angeles. The monthly average compound concentrations predicted by the transport model were compared to atmospheric measurements made at monitoring sites within the study area during 1982. The predicted seasonal variation and absolute values of the concentrations of the more stable compounds are found to be in reasonable agreement with the ambient observations. While model predictions for the higher molecular weight polycyclic aromatic hydrocarbons (PAH) are in agreement with ambient observations, lower molecular weight PAH show much higher predicted than measured atmospheric concentrations in the particle phase, indicating atmospheric decay by chemical reactions or evaporation from the particle phase. The atmospheric concentrations of dicarboxylic acids and aromatic polycarboxylic acids greatly exceed the contributions that

  16. A diffusion model for use with directional samplers. [particle dispersion in atmosphere

    Science.gov (United States)

    Anbar, D.

    1978-01-01

    The paper presents a mathematical model for describing dispersion processes of airborne particles in the atmosphere. The process is described as a superposition of independent Brownian motion processes with drifts and a boundary at zero. It is assumed that the terrain is flat and of a homogeneous roughness. All sources are assumed to be point sources. The time dependencies of emission rates, wind speed, wind direction, and atmospheric conditions are taken into account.

  17. Characterization of high molecular weight compounds in urban atmospheric particles

    Directory of Open Access Journals (Sweden)

    V. Samburova

    2005-01-01

    Full Text Available The chemical nature of a large fraction of ambient organic aerosol particles is not known. However, high molecular weight compounds (often named humic-like substances have recently been detected by several authors and these compounds seem to account for a significant fraction of the total organic aerosol mass. Due to the unknown chemical structure of these compounds a quantification as well as a determination of their molecular weight is difficult. In this paper we investigate water soluble humic-like substances in ambient urban aerosol using size exclusion chromatography-UV spectroscopy and laser desorption/ionization mass spectrometry. A careful method evaluation shows that both methods complement each other and that both are needed to learn more about the molecular weight distribution and the concentration of humic-like substances. An upper molecular weight limit of humic-like substances of about 700 Da and a concentration of 0.2–1.8 µg/m3 air can be estimated corresponding to 8–33% of the total organic carbon for an urban background site.

  18. Black-carbon absorption enhancement in the atmosphere determined by particle mixing state

    Science.gov (United States)

    Liu, Dantong; Whitehead, James; Alfarra, M. Rami; Reyes-Villegas, Ernesto; Spracklen, Dominick V.; Reddington, Carly L.; Kong, Shaofei; Williams, Paul I.; Ting, Yu-Chieh; Haslett, Sophie; Taylor, Jonathan W.; Flynn, Michael J.; Morgan, William T.; McFiggans, Gordon; Coe, Hugh; Allan, James D.

    2017-02-01

    Atmospheric black carbon makes an important but poorly quantified contribution to the warming of the global atmosphere. Laboratory and modelling studies have shown that the addition of non-black-carbon materials to black-carbon particles may enhance the particles’ light absorption by 50 to 60% by refracting and reflecting light. Real-world experimental evidence for this `lensing’ effect is scant and conflicting, showing that absorption enhancements can be less than 5% or as large as 140%. Here we present simultaneous quantifications of the composition and optical properties of individual atmospheric black-carbon particles. We show that particles with a mass ratio of non-black carbon to black carbon of less than 1.5, which is typical of fresh traffic sources, are best represented as having no absorption enhancement. In contrast, black-carbon particles with a ratio greater than 3, which is typical of biomass-burning emissions, are best described assuming optical lensing leading to an absorption enhancement. We introduce a generalized hybrid model approach for estimating scattering and absorption enhancements based on laboratory and atmospheric observations. We conclude that the occurrence of the absorption enhancement of black-carbon particles is determined by the particles’ mass ratio of non-black carbon to black carbon.

  19. The characterization of atmospheric aerosols: Application to heterogeneous gas-particle reactions

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, J.M.; Henson, B.F.; Wilson, K.R. [Los Alamos National Lab., NM (United States); Prather, K.A.; Noble, C.A. [Univ. of California, Riverside, CA (United States)

    1998-12-31

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project of the Los Alamos National Laboratory (LANL). The objective of this collaborative research project is the measurement and modeling of atmospheric aerosols and heterogeneous (gas/aerosol) chemical reactions. The two major accomplishments are single particle characterization of tropospheric particles and experimental investigation of simulated stratospheric particles and reactions thereon. Using aerosol time-of-flight mass spectrometry, real-time and composition measurements of single particles are performed on ambient aerosol samples. This technique allows particle size distributions for chemically distinct particle types to be described. The thermodynamics and chemical reactivity of polar stratospheric clouds are examined using vapor deposited thin ice films. Employing nonlinear optical methods, as well as other techniques, phase transitions on both water and acid ices are monitored as a function of temperature or the addition of gases.

  20. Ionizer assisted air filtration for collection of submicron and ultrafine particles-evaluation of long-term performance and influencing factors.

    Science.gov (United States)

    Shi, Bingbing; Ekberg, Lars

    2015-06-02

    Previous research has demonstrated that unipolar ionization can enhance the filter performance to collect airborne particles, aeroallergens, and airborne microorganisms, without affecting the filter pressure drop. However, there is a lack of research on the long-term system performance as well as the influence of environmental and operational parameters. In this paper, both field and laboratory tests were carried out to evaluate the long-term particle collection efficiency of a synthetic filter of class M6 with and without ionization. The effect of air velocity, temperature, relative humidity, and particle concentration were further investigated in laboratory tests. Results showed that ionization enhanced the filtration efficiency by 40%-units during most of the operation time. When the ionization system was managed by periodically switching the ionizer polarity, the filtration efficiency against PM0.3-0.5 was maintained above 50% during half a year. Furthermore, the pressure drop of the ionizer-assisted M6 filter was 25-30% lower than that of a filter of class F7. The evaluation of various influencing factors demonstrated that (1) air moisture reduced the increase of filtration efficiency; (2) higher upstream particle concentration and air velocity decreased the filtration efficiency; and (3) the air temperature had very limited effect on the filtration efficiency.

  1. Experimental evidence for the role of ions in particle nucleation under atmospheric conditions

    DEFF Research Database (Denmark)

    Svensmark, Henrik; Pedersen, Jens Olaf Pepke; Marsh, N.D.

    2007-01-01

    Experimental studies of aerosol nucleation in air, containing trace amounts of ozone, sulphur dioxide and water vapour at concentrations relevant for the Earth's atmosphere, are reported. The production of new aerosol particles is found to be proportional to the negative ion density and yields...... nucleation rates of the order of 0.1 1 cm(-3) s(-1). This suggests that the ions are active in generating an atmospheric reservoir of small thermodynamically stable clusters, which are important for nucleation processes in the atmosphere and ultimately for cloud formation....

  2. Biological effects of atmospheric particles on human bronchial epithelial cells. Comparison with diesel exhaust particles.

    Science.gov (United States)

    Baulig, Augustin; Sourdeval, Matthieu; Meyer, Martine; Marano, Francelyne; Baeza-Squiban, Armelle

    2003-01-01

    Epidemiological studies have associated the increase of respiratory disorders with high levels of ambient particulate matter (PM) levels although the underlying biological mechanisms are unclear. PM are a complex mixture of particles with different origins but in urban areas, they mainly contain soots from transport like Diesel exhaust particles (DEP). In order to determine whether PM biological effects can be explained by the presence of DEP, the effects of urban PM, DEP and carbon black particles (CB) were compared on a human bronchial epithelial cell line (16-HBE14o-). Two types of PM were used : reference material (RPM) and PM with an aerodynamic diameter particles. However, DEP and to a lower extent PM inhibited cell proliferation, induced the release of a pro-inflammatory cytokine, GM-CSF, and generated a pro-oxidant state as shown by the increased intracellular peroxides production. By contrast, CB never induced such effects. Nevertheless CB are more endocytosed than DEP whereas PM are the less endocytosed particles. In conclusion, PM induced to a lower extent the same biological effects than DEP in 16-HBE cells suggesting that particle characteristics should be thoroughly considered in order to clearly correlate adverse effects of PM to their composition and to clarify the role of DEP in PM effects.

  3. Seasonal differences of the atmospheric particle size distribution in a metropolitan area in Japan.

    Science.gov (United States)

    Fujitani, Yuji; Kumar, Prashant; Tamura, Kenji; Fushimi, Akihiro; Hasegawa, Shuich; Takahashi, Katsuyuki; Tanabe, Kiyoshi; Kobayashi, Shinji; Hirano, Seishiro

    2012-10-15

    We compared the effect of ambient temperature observed in two different seasons on the size distribution and particle number concentration (PNC) as a function of distance (up to ~250 m) from a major traffic road (25% of the vehicles are heavy-duty diesel vehicles). The modal particle diameter was found between 10 and 30 nm at the roadside in the winter. However, there was no peak for this size range in the summer, even at the roadside. Ambient temperature affects both the atmospheric dilution ratio (DR) and the evaporation rate of particles, thus it affects the decay rate of PNC. We corrected the DR effect in order to focus on the effect of particle evaporation on PNC decay. The decay rate of PNC with DR was found to depend on the season and particle diameter. During the winter, the decay rate for smaller particles (particles >30 nm in diameter, the decay rate was nearly the same during both seasons. This distinction between particles less than or greater than 30 nm in diameter reflects differences in particle volatility properties. Mass-transfer theory was used to estimate evaporation rates of C20-C36 n-alkane particles, which are the major n-alkanes in diesel exhaust particles. The C20-C28 n-alkanes of 30-nm particles completely evaporate at 31.2 °C (summer), and their lifetime is shorter than the transport time of air masses in our region of interest. Absence of the peak at 10-30 nm and the low decay rate of PNC particles near the exhaust pipes of vehicles, and complete evaporation of semivolatile materials before they reached the roadside. These results suggest that the lifetime of particles particles show distinctly different spatial distributions depending on the season.

  4. The generation of diesel exhaust particle aerosols from a bulk source in an aerodynamic size range similar to atmospheric particles

    Directory of Open Access Journals (Sweden)

    Daniel J Cooney

    2008-08-01

    Full Text Available Daniel J Cooney1, Anthony J Hickey21Department of Biomedical Engineering; 2School of Pharmacy, University of North Carolina, Chapel Hill, NC, USAAbstract: The influence of diesel exhaust particles (DEP on the lungs and heart is currently a topic of great interest in inhalation toxicology. Epidemiological data and animal studies have implicated airborne particulate matter and DEP in increased morbidity and mortality due to a number of cardiopulmonary diseases including asthma, chronic obstructive pulmonary disorder, and lung cancer. The pathogeneses of these diseases are being studied using animal models and cell culture techniques. Real-time exposures to freshly combusted diesel fuel are complex and require significant infrastructure including engine operations, dilution air, and monitoring and control of gases. A method of generating DEP aerosols from a bulk source in an aerodynamic size range similar to atmospheric DEP would be a desirable and useful alternative. Metered dose inhaler technology was adopted to generate aerosols from suspensions of DEP in the propellant hydrofluoroalkane 134a. Inertial impaction data indicated that the particle size distributions of the generated aerosols were trimodal, with count median aerodynamic diameters less than 100 nm. Scanning electron microscopy of deposited particles showed tightly aggregated particles, as would be expected from an evaporative process. Chemical analysis indicated that there were no major changes in the mass proportion of 2 specific aromatic hydrocarbons (benzo[a]pyrene and benzo[k]fluoranthene in the particles resulting from the aerosolization process.Keywords: diesel exhaust particles, aerosol, inhalation toxicology

  5. Morphology and mixing state of atmospheric particles: Links to optical properties and cloud processing

    Science.gov (United States)

    China, Swarup

    Atmospheric particles are ubiquitous in Earth's atmosphere and impact the environment and the climate while affecting human health and Earth's radiation balance, and degrading visibility. Atmospheric particles directly affect our planet's radiation budget by scattering and absorbing solar radiation, and indirectly by interacting with clouds. Single particle morphology (shape, size and internal structure) and mixing state (coating by organic and inorganic material) can significantly influence the particle optical properties as well as various microphysical processes, involving cloud-particle interactions and including heterogeneous ice nucleation and water uptake. Conversely, aerosol cloud processing can affect the morphology and mixing of the particles. For example, fresh soot has typically an open fractal-like structure, but aging and cloud processing can restructure soot into more compacted shapes, with different optical and ice nucleation properties. During my graduate research, I used an array of electron microscopy and image analysis tools to study morphology and mixing state of a large number of individual particles collected during several field and laboratory studies. To this end, I investigated various types of particles such as tar balls (spherical carbonaceous particles emitted during biomass burning) and dust particles, but with a special emphasis on soot particles. In addition, I used the Stony Brook ice nucleation cell facility to investigate heterogeneous ice nucleation and water uptake by long-range transported particles collected at the Pico Mountain Observatory, in the Archipelago of the Azores. Finally, I used ice nucleation data from the SAAS (Soot Aerosol Aging Study) chamber study at the Pacific Northwest National Laboratory to understand the effects that ice nucleation and supercooled water processing has on the morphology of residual soot particles. Some highlights of our findings and implications are discussed next. We found that the

  6. Nuclear fuel particles in the environment - characteristics, atmospheric transport and skin doses

    Energy Technology Data Exchange (ETDEWEB)

    Poellaenen, R

    2002-05-01

    In the present thesis, nuclear fuel particles are studied from the perspective of their characteristics, atmospheric transport and possible skin doses. These particles, often referred to as 'hot' particles, can be released into the environment, as has happened in past years, through human activities, incidents and accidents, such as the Chernobyl nuclear power plant accident in 1986. Nuclear fuel particles with a diameter of tens of micrometers, referred to here as large particles, may be hundreds of kilobecquerels in activity and even an individual particle may present a quantifiable health hazard. The detection of individual nuclear fuel particles in the environment, their isolation for subsequent analysis and their characterisation are complicated and require well-designed sampling and tailored analytical methods. In the present study, the need to develop particle analysis methods is highlighted. It is shown that complementary analytical techniques are necessary for proper characterisation of the particles. Methods routinely used for homogeneous samples may produce erroneous results if they are carelessly applied to radioactive particles. Large nuclear fuel particles are transported differently in the atmosphere compared with small particles or gaseous species. Thus, the trajectories of gaseous species are not necessarily appropriate for calculating the areas that may receive large particle fallout. A simplified model and a more advanced model based on the data on real weather conditions were applied in the case of the Chernobyl accident to calculate the transport of the particles of different sizes. The models were appropriate in characterising general transport properties but were not able to properly predict the transport of the particles with an aerodynamic diameter of tens of micrometers, detected at distances of hundreds of kilometres from the source, using only the current knowledge of the source term. Either the effective release height has

  7. Atmospheric data over a solar cycle: no connection between galactic cosmic rays and new particle formation

    Directory of Open Access Journals (Sweden)

    M. Kulmala

    2010-02-01

    Full Text Available Aerosol particles affect the Earth's radiative balance by directly scattering and absorbing solar radiation and, indirectly, through their activation into cloud droplets. Both effects are known with considerable uncertainty only, and translate into even bigger uncertainties in future climate predictions. More than a decade ago, variations in galactic cosmic rays were suggested to closely correlate with variations in atmospheric cloud cover and therefore constitute a driving force behind aerosol-cloud-climate interactions. Later, the enhancement of atmospheric aerosol particle formation by ions generated from cosmic rays was proposed as a physical mechanism explaining this correlation. Here, we report unique observations on atmospheric aerosol formation based on measurements at the SMEAR II station, Finland, over a solar cycle (years 1996–2008 that shed new light on these presumed relationships. Our analysis shows that none of the quantities related to aerosol formation correlates with the cosmic ray-induced ionisation intensity (CRII. We also examined the contribution of ions to new particle formation on the basis of novel ground-based and airborne observations. A consistent result is that ion-induced formation contributes typically significantly less than 10% to the number of new particles, which would explain the missing correlation between CRII and aerosol formation. Our main conclusion is that galactic cosmic rays appear to play a minor role for atmospheric aerosol formation events, and so for the connected aerosol-climate effects as well.

  8. Atmospheric data over a solar cycle: no connection between galactic cosmic rays and new particle formation

    Directory of Open Access Journals (Sweden)

    M. Kulmala

    2009-10-01

    Full Text Available Aerosol particles affect the Earth's radiative balance by directly scattering and absorbing solar radiation and, indirectly, through their activation into cloud droplets. Both effects are known with considerable uncertainty only, and translate into even bigger uncertainties in future climate predictions. More than a decade ago, variations in galactic cosmic rays were suggested to closely correlate with variations in atmospheric cloud cover and therefore constitute a driving force behind aerosol-cloud-climate interactions. Later, the enhancement of atmospheric aerosol particle formation by ions generated from cosmic rays was proposed as a physical mechanism explaining this correlation. Here, we report unique observations on atmospheric aerosol formation based on measurements at the SMEAR II station, Finland, over a solar cycle (years 1996–2008 that shed new light on these presumed relationships. Our analysis shows that none of the quantities related to aerosol formation correlates with the cosmic ray-induced ionisation intensity (CRII. We also examined the contribution of ions to new particle formation on the basis of novel ground-based and airborne observations. A consistent result is that ion-induced formation contributes typically less than 10% to the number of new particles, which would explain the missing correlation between CRII and aerosol formation. Our main conclusion is that galactic cosmic rays appear to play a minor role for atmospheric aerosol formation, and so for the connected aerosol-climate effects as well.

  9. Organochlorine Pesticides and Polychlorinated Biphenyls in Atmospheric Particles Collected in Zagreb, Croatia

    Directory of Open Access Journals (Sweden)

    Marija Dvoršćak

    2015-07-01

    Full Text Available We studied the occurrence and levels of hexachlorobenzene, α-, β-, and γ-hexachlorocyclo-hexane, 4,4'-DDT, 4,4'-DDE, 4,4'-DDD, and 17 PCBs (six indicator and eleven other toxicologically significant congeners in PM10 and/or PM2.5 particle fractions collected between 2000 and 2003 and in 2010 at a site in the northern residential part of Zagreb, Croatia. Twenty-four-hour particle samples were collected on glass or quartz microfibre filters from approximately 100 m3 of ambient air per filter. Filters with particles collected over seven consecutive days were combined for ultrasonic extraction with 1:1 acetone:n-hexane mixture followed by capillary gas chromatography with electron capture detection. In the monitored periods, the mass concentrations of organochlorine compounds in atmospheric particles were characteristic of global environmental pollution and showed a decreasing trend. Local input was observed only for γ-hexachlorocyclohexane. There were no pronounced seasonal variations in the mass fraction levels of any pesticide or PCB in airborne particles. A decreasing trend in the mass concentrations of some compounds with higher air temperatures was mostly related to the lower particle concentrations in warmer seasons and, consequently, to less particle-bound organochlorine compounds in the atmosphere.

  10. Aqueous Processing of Atmospheric Organic Particles in Cloud Water Collected via Aircraft Sampling

    Energy Technology Data Exchange (ETDEWEB)

    Boone, Eric J.; Laskin, Alexander; Laskin, Julia; Wirth, Christopher; Shepson, Paul B.; Stirm, Brian H.; Pratt, Kerri A.

    2015-07-21

    Cloud water and below-cloud atmospheric particle samples were collected onboard a research aircraft during the Southern Oxidant and Aerosol Study (SOAS) over a forested region of Alabama in June 2013. The organic molecular composition of the samples was studied to gain insights into the aqueous-phase processing of organic compounds within cloud droplets. High resolution mass spectrometry with nanospray desorption electrospray ionization and direct infusion electrospray ionization were utilized to compare the organic composition of the particle and cloud water samples, respectively. Isoprene and monoterpene-derived organosulfates and oligomers were identified in both the particles and cloud water, showing the significant influence of biogenic volatile organic compound oxidation above the forested region. While the average O:C ratios of the organic compounds were similar between the atmospheric particle and cloud water samples, the chemical composition of these samples was quite different. Specifically, hydrolysis of organosulfates and formation of nitrogen-containing compounds were observed for the cloud water when compared to the atmospheric particle samples, demonstrating that cloud processing changes the composition of organic aerosol.

  11. Pollution characteristics of atmospheric fine particles and their secondary components in the atmosphere of Shenzhen in summer and in winter

    Institute of Scientific and Technical Information of China (English)

    NIU; Yuwen; HE; Lingyan; HU; Min; ZHANG; Jing; ZHAO; Yunliang

    2006-01-01

    Two field measurements for atmospheric fine particles were conducted in Baoan district of Shenzhen during the summer and winter in 2004. Totally 30 sets of 24 h samples were collected, and then the mass concentrations and chemical compositions were determined. The seasonal variations and secondary pollution characteristics of fine particles during the sampling periods were discussed with meteorological factors. The results show that seasonal variations of atmospheric particles are significant in Shenzhen. The average mass concentrations of PM2.5 and PM10 in summer were 35 μg·m-3 and 57 μg·m-3, respectively, and those in winter were 99 μg·m-3 and 135 μg·m-3, respectively. The concentrations of both PM2.5 and PM10 in winter increased 184% and 137%, respectively, compared to those in summer. PM2.5 accounted for 61% and 75% of PM10 in summer and in winter, respectively, indicating severe fine particle pollution in Shenzhen. During the summer and winter sampling periods, the mean OC/EC ratios were 3.4 and 1.6, respectively. The estimated secondary organic carbon (SOC) averagely accounted for 56% and 6% of the total OC in summer and in winter, respectively, which implies a major contribution of SOC to OC in summer. During the continuous high temperature period in summer, both the concentrations and fractions of secondary aerosol components in PM2.5 were highly elevated, suggesting severe secondary pollution again. The prevailing wind was from South China Sea in summer, and the air quality was good. The prevailing wind in winter was from Mainland China to the north, and the polluted air mass led to poor air quality.

  12. Utilitarian Opacity Model for Aggregate Particles in Protoplanetary Nebulae and Exoplanet Atmospheres

    CERN Document Server

    Cuzzi, Jeffrey N; Davis, Sanford S

    2013-01-01

    As small solid grains grow into larger ones in protoplanetary nebulae, or in the cloudy atmospheres of exoplanets, they generally form porous aggregates rather than solid spheres. A number of previous studies have used highly sophisticated schemes to calculate opacity models for irregular, porous particles with size much smaller than a wavelength. However, mere growth itself can affect the opacity of the medium in far more significant ways than the detailed compositional and/or structural differences between grain constituents once aggregate particle sizes exceed the relevant wavelengths. This physics is not new; our goal here is to provide a model that provides physical insight and is simple to use in the increasing number of protoplanetary nebula evolution, and exoplanet atmosphere, models appearing in recent years, yet quantitatively captures the main radiative properties of mixtures of particles of arbitrary size, porosity, and composition. The model is a simple combination of effective medium theory with...

  13. Influence of Ultrafine 2CaO·SiO2 Powder on Hydration Properties of Reactive Powder Concrete

    Directory of Open Access Journals (Sweden)

    Hongfang Sun

    2015-09-01

    Full Text Available In this research, we assessed the influence of an ultrafine 2CaO·SiO2 powder on the hydration properties of a reactive powder concrete system. The ultrafine powder was manufactured through chemical combustion method. The morphology of ultrafine powder and the development of hydration products in the cement paste prepared with ultrafine powder were investigated by scanning electron microscopy (SEM, mineralogical composition were determined by X-ray diffraction, while the heat release characteristics up to the age of 3 days were investigated by calorimetry. Moreover, the properties of cementitious system in fresh and hardened state (setting time, drying shrinkage, and compressive strength with 5% ordinary Portland cement replaced by ultrafine powder were evaluated. From SEM micrographs, the particle size of ultrafine powder was found to be up to several hundred nanometers. The hydration product started formulating at the age of 3 days due to slow reacting nature of belitic 2CaO·SiO2. The initial and final setting times were prolonged and no significant difference in drying shrinkage was observed when 5% ordinary Portland cement was replaced by ultrafine powder. Moreover, in comparison to control reactive powder concrete, the reactive powder concrete containing ultrafine powder showed improvement in compressive strength at and above 7 days of testing. Based on above, it can be concluded that the manufactured ultrafine 2CaO·SiO2 powder has the potential to improve the performance of a reactive powder cementitious system.

  14. In2O3 Ultrafine Powder Synthesis by Sol-Gel Method

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The precursor of ultrafine In2O3 powder was prepared by the hydrolysis, peptization and gelation of InC13 @4H2O used as raw material.After calcination, ultrafine In2O3 powder was obtained. The particles were characterized by the methods of thermo-gravimetric and differential thermal analysis (TG-DTA), X-ray diffractometry (XRD) and transmission electron microscopy (TEM), respectively.

  15. The role of low-volatility organic compounds in initial particle growth in the atmosphere

    Science.gov (United States)

    Tröstl, Jasmin; Chuang, Wayne K.; Gordon, Hamish; Heinritzi, Martin; Yan, Chao; Molteni, Ugo; Ahlm, Lars; Frege, Carla; Bianchi, Federico; Wagner, Robert; Simon, Mario; Lehtipalo, Katrianne; Williamson, Christina; Craven, Jill S.; Duplissy, Jonathan; Adamov, Alexey; Almeida, Joao; Bernhammer, Anne-Kathrin; Breitenlechner, Martin; Brilke, Sophia; Dias, Antònio; Ehrhart, Sebastian; Flagan, Richard C.; Franchin, Alessandro; Fuchs, Claudia; Guida, Roberto; Gysel, Martin; Hansel, Armin; Hoyle, Christopher R.; Jokinen, Tuija; Junninen, Heikki; Kangasluoma, Juha; Keskinen, Helmi; Kim, Jaeseok; Krapf, Manuel; Kürten, Andreas; Laaksonen, Ari; Lawler, Michael; Leiminger, Markus; Mathot, Serge; Möhler, Ottmar; Nieminen, Tuomo; Onnela, Antti; Petäjä, Tuukka; Piel, Felix M.; Miettinen, Pasi; Rissanen, Matti P.; Rondo, Linda; Sarnela, Nina; Schobesberger, Siegfried; Sengupta, Kamalika; Sipilä, Mikko; Smith, James N.; Steiner, Gerhard; Tomè, Antònio; Virtanen, Annele; Wagner, Andrea C.; Weingartner, Ernest; Wimmer, Daniela; Winkler, Paul M.; Ye, Penglin; Carslaw, Kenneth S.; Curtius, Joachim; Dommen, Josef; Kirkby, Jasper; Kulmala, Markku; Riipinen, Ilona; Worsnop, Douglas R.; Donahue, Neil M.; Baltensperger, Urs

    2016-05-01

    About half of present-day cloud condensation nuclei originate from atmospheric nucleation, frequently appearing as a burst of new particles near midday. Atmospheric observations show that the growth rate of new particles often accelerates when the diameter of the particles is between one and ten nanometres. In this critical size range, new particles are most likely to be lost by coagulation with pre-existing particles, thereby failing to form new cloud condensation nuclei that are typically 50 to 100 nanometres across. Sulfuric acid vapour is often involved in nucleation but is too scarce to explain most subsequent growth, leaving organic vapours as the most plausible alternative, at least in the planetary boundary layer. Although recent studies predict that low-volatility organic vapours contribute during initial growth, direct evidence has been lacking. The accelerating growth may result from increased photolytic production of condensable organic species in the afternoon, and the presence of a possible Kelvin (curvature) effect, which inhibits organic vapour condensation on the smallest particles (the nano-Köhler theory), has so far remained ambiguous. Here we present experiments performed in a large chamber under atmospheric conditions that investigate the role of organic vapours in the initial growth of nucleated organic particles in the absence of inorganic acids and bases such as sulfuric acid or ammonia and amines, respectively. Using data from the same set of experiments, it has been shown that organic vapours alone can drive nucleation. We focus on the growth of nucleated particles and find that the organic vapours that drive initial growth have extremely low volatilities (saturation concentration less than 10-4.5 micrograms per cubic metre). As the particles increase in size and the Kelvin barrier falls, subsequent growth is primarily due to more abundant organic vapours of slightly higher volatility (saturation concentrations of 10-4.5 to 10

  16. Hydrostatic Simulation of Earth's Atmospheric Gas Using Multi-particle Collision Dynamics

    Science.gov (United States)

    Pattisahusiwa, Asis; Purqon, Acep; Viridi, Sparisoma

    2016-01-01

    Multi-particle collision dynamics (MPCD) is a mesoscopic simulation method to simulate fluid particle-like flows. MPCD has been widely used to simulate various problems in condensed matter. In this study, hydrostatic behavior of gas in the Earth's atmospheric layer is simulated by using MPCD method. The simulation is carried out by assuming the system under ideal state and is affected only by gravitational force. Gas particles are homogeneous and placed in 2D box. Interaction of the particles with the box is applied through implementation of boundary conditions (BC). Periodic BC is applied on the left and the right side, specular reflection on the top side, while bounce-back on the bottom side. Simulation program is executed in Arch Linux and running in notebook with processor Intel i5 @2700 MHz with 10 GB DDR3 RAM. The results show behaviors of the particles obey kinetic theory for ideal gas when gravitational acceleration value is proportional to the particle mass. Density distribution as a function of altitude also meets atmosphere's hydrostatic theory.

  17. Vascular and lung function related to ultrafine and fine particles exposure assessed by personal and indoor monitoring: a cross-sectional study

    DEFF Research Database (Denmark)

    Olsen, Yulia; Karottki, Dorina Gabriela; Jensen, Ditte Marie

    2014-01-01

    -related effects. Methods: Associations between vascular and lung function, inflammation markers and exposure in terms of particle number concentration (PNC; d = 10-300 nm) were studied in a cross-sectional design with personal and home indoor monitoring in the Western Copenhagen Area, Denmark. During 48-h, PNC...... and PM2.5 were monitored in living rooms of 60 homes with 81 non-smoking subjects (30-75 years old), 59 of whom carried personal monitors both when at home and away from home. We measured lung function in terms of the FEV1/FVC ratio, microvascular function (MVF) and pulse amplitude by digital artery...... tonometry, blood pressure and biomarkers of inflammation including C-reactive protein, and leukocyte counts with subdivision in neutrophils, eosinophils, monocytes, and lymphocytes in blood. Results: PNC from personal and stationary home monitoring showed weak correlation (r = 0.15, p = 0.24). Personal UFP...

  18. Characterization of Atmospheric Aerosol Particles from a Mining City in Southwest China Using Electron Probe microanalysis

    Science.gov (United States)

    Cheng, X.; Huang, Y.; Lu, H., III; Liu, Z., IV; Wang, N. V.

    2015-12-01

    Xin Cheng1, Yi Huang1*, Huilin Lu2, Zaidong Liu2, Ningming Wang21 Key Laboratory of Geological Nuclear Technology of Sichuan Province, College of Earth Science, Chengdu University of Technology, Chengdu 610059, China. ; E-mail:chengxin_cdut@163.com 2 College of Earth Science, Chengdu University of Technology, Chengdu 610059, China. ; *Corresponding author: E-mail: huangyi@cdut.cn Panzhihua is a mining city located at Pan-Xi Rift valley, southwest China. It has a long industrial history of vanadium-titanium magnetite mining, iron and steel smelting, and coal-fired power plants. Atomospheric environment has been seriously contaminated with airborne paticles, which is threatening human health.The harmful effects of aerosols are dependent on certain characteristics such as microphysical properties. However, few studsies have been carried out on morphological information contained on single atmospheric particles in this area. In this study, we provide a detailed morphologically and chemically characterization of airborne particles collected at Panzhihua city in October, 2014, using a quantitative single particle analysis based on EPXMA. The results indicate that based on their chemical composition, five major types of particles were identified. Among these, aluminosilicate particles have typical spherical shapes and are produced during the high-temperature combustion; Fe-containing particles contains high level of Mn, and more likely originated from mineralogical and steel industry; Si-containing particles can originate from mineralogical source; V-Ti-Mn-containing particles are also produced by steel industry; Ca-containing particles,these particles are CaCO3, mainly from the mining of limestone mine. The results help us on tracing and partitioning different sources of atomospheric particles in the industrial area. Fig.1 Fe-rich shperical particles

  19. Processing of atmospheric particles caught in the act via STXM/NEXAFS

    Science.gov (United States)

    Steimer, S.; Lampimäki, M.; Grzinic, G.; Coz, E.; Watts, B.; Raabe, J.; Ammann, M.

    2012-12-01

    Atmospheric aerosols are an important focus of environmental research due to their effect on climate and human health. Among their main constituents are mineral dust and organic particles. Both types of particles directly and indirectly affect our climate through scattering and absorption of radiation and through acting as cloud condensation nuclei respectively. Organic particles are also of significant concern with respect to their health effects. Mineral dust particles in addition serve as a primary external iron source to the open ocean and the bioavailability of iron from these particles is highly dependent on the oxidation state of the metal. The environmental impact of atmospheric particles depends on their physical and chemical properties, which might change upon chemical ageing. In this study we therefore investigated the changes in chemical composition and morphology of mineral dust and organic particle proxies (Arizona test dust and shikimic acid, respectively) upon in situ exposure to ozone or nitrogen oxides in presence of humidity. This was achieved by monitoring changes at the C and O K-edges as well as the metal L-edges via scanning transmission X-ray microscopy (STXM) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. Measurements were conducted at the PolLux beamline at Swiss Light Source. All experiments were conducted in an environmental micro reactor, designed specifically for the end station, to enable the investigation in situ. We observed oxidation of shikimic acid particles in situ during exposure to ozone at different humidities, whereby humidity was found to be a critical factor controlling the rate of the reaction. We also obtained well resolved iron distribution maps from the individual submicrometer size mineral dust particles before and after exposure to nitrogen oxides.

  20. Tight coupling of particle size, number and composition in atmospheric cloud droplet activation

    Directory of Open Access Journals (Sweden)

    D. O. Topping

    2012-04-01

    Full Text Available The substantial uncertainty in the indirect effect of aerosol particles on radiative forcing in large part arises from the influences of atmospheric aerosol particles on (i the brightness of clouds, exerting significant shortwave cooling with no appreciable compensation in the long wave, and on (ii their ability to precipitate, with implications for cloud cover and lifetime.

    Predicting the ambient conditions at which aerosol particles may become cloud droplets is largely reliant on an equilibrium relationship derived by Köhler (1936. However, the theoretical basis of the relationship restricts its application to particles solely comprising involatile compounds and water, whereas a substantial fraction of particles in the real atmosphere will contain potentially thousands of semi-volatile organic compounds in addition to containing semi-volatile inorganic components such as ammonium nitrate.

    We show that equilibration of atmospherically reasonable concentrations of organic compounds with a growing particle as the ambient humidity increases has potentially larger implications on cloud droplet formation than any other equilibrium compositional dependence, owing to inextricable linkage between the aerosol composition, a particles size and concentration under ambient conditions.

    Whilst previous attempts to account for co-condensation of gases other than water vapour have been restricted to one inorganic condensate, our method demonstrates that accounting for the co-condensation of any number of organic compounds substantially decreases the saturation ratio of water vapour required for droplet activation. This effect is far greater than any other compositional dependence; more so even than the unphysical effect of surface tension reduction in aqueous organic mixtures, ignoring differences in bulk and surface surfactant concentrations.

  1. Peculiarities in atmospheric particle number and size-resolved speciation in an urban area in the western Mediterranean: Results from the DAURE campaign

    Science.gov (United States)

    Reche, C.; Viana, M.; Moreno, T.; Querol, X.; Alastuey, A.; Pey, J.; Pandolfi, M.; Prévôt, A.; Mohr, C.; Richard, A.; Artiñano, B.; Gomez-Moreno, F. J.; Cots, N.

    2011-09-01

    Air quality degradation problems in urban environments are mainly due to road traffic emissions. In northern and central European cities extensive investigations have been carried out on the variability of number of ultrafine particles and black carbon, whereas studies in southern-Europe have traditionally focused on chemical speciation, resulting in insufficient information to characterise urban aerosol processes. Accordingly, sources and processes controlling atmospheric pollutants were evaluated during the international DAURE campaign in Barcelona (Spain), a typical urban environment in the western Mediterranean, by means of continuous measurements of particle number, black carbon, PMx, particulate nitrate and particulate sulphate concentrations. Results provided evidence of the influence of three PM sources of interest: road traffic, construction-demolition works and shipping emissions. Road traffic governs the daily cycle of black carbon, a number of gaseous pollutants and the finer fraction of PM. Evaluation of the coarse aerosol (PM 2.5-10) daily cycle furnished evidence of the influence of construction-demolition works. These activities could increase hourly PM 2.5-10 levels by up to 8 μg m -3 on an annual hourly mean basis. Finally, shipping emissions were traced by means of SO 2 concentrations, which peak at a time different from that of other gaseous pollutants owing to the regular daytime onshore breeze bringing harbour emissions at midday. Moreover, a major local contribution of secondary aerosols was detected with elevated particle number levels at midday when nucleation processes are favoured by photochemistry and lower pollution levels. Particle number data were also analysed in search for the primary emission of vehicle exhaust (N1) and the secondary parts from gaseous precursors, primary parts from non-traffic sources, and/or particles inherited in the air mass (N2). N2 fraction accounted for 40% of number concentrations, ranging from 37% during

  2. Contribution of Arctic seabird-colony ammonia to atmospheric particles and cloud-albedo radiative effect

    Science.gov (United States)

    Croft, B.; Wentworth, G. R.; Martin, R. V.; Leaitch, W. R.; Murphy, J. G.; Murphy, B. N.; Kodros, J. K.; Abbatt, J. P. D.; Pierce, J. R.

    2016-11-01

    The Arctic region is vulnerable to climate change and able to affect global climate. The summertime Arctic atmosphere is pristine and strongly influenced by natural regional emissions, which have poorly understood climate impacts related to atmospheric particles and clouds. Here we show that ammonia from seabird-colony guano is a key factor contributing to bursts of newly formed particles, which are observed every summer in the near-surface atmosphere at Alert, Nunavut, Canada. Our chemical-transport model simulations indicate that the pan-Arctic seabird-influenced particles can grow by sulfuric acid and organic vapour condensation to diameters sufficiently large to promote pan-Arctic cloud-droplet formation in the clean Arctic summertime. We calculate that the resultant cooling tendencies could be large (about -0.5 W m-2 pan-Arctic-mean cooling), exceeding -1 W m-2 near the largest seabird colonies due to the effects of seabird-influenced particles on cloud albedo. These coupled ecological-chemical processes may be susceptible to Arctic warming and industrialization.

  3. Source apportionment of single aerosol particles in the atmosphere of Shanghai city

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A nuclear microprobe with high spatial resolution and high analyti cal sensitivity was applied to analyze atmospheric aerosol at five monitoring sites in Shanghai city. Meantime, a new pattern recognition technique, which used the micro PIXE spectrum of a single aerosol particle as its fingerprint, was developed to identify the origin of the particle. The results showed that the major contributors to the at mosphere pollution were soil dust (31.6%), building dust (30.8%), and the next were vehicle exhaust (13.7%), metallurgic industry excrements (5.6%), oil combustion (5%) and coal combustion (2.3%). Besides these, about 10% of the particles could not be identified. Based on the cluster analysis of these particles, they could be divided into eight groups. By inference, they might belong to some sub-pollution sources from soil dust, building dust and metallurgic industry excrements. Moreover, some new pollution sources from tyres and chemical plants were also revealed.

  4. Ablation and Chemical Alteration of Cosmic Dust Particles during Entry into the Earth’s Atmosphere

    Science.gov (United States)

    Rudraswami, N. G.; Shyam Prasad, M.; Dey, S.; Plane, J. M. C.; Feng, W.; Carrillo-Sánchez, J. D.; Fernandes, D.

    2016-12-01

    Most dust-sized cosmic particles undergo ablation and chemical alteration during atmospheric entry, which alters their original properties. A comprehensive understanding of this process is essential in order to decipher their pre-entry characteristics. The purpose of the study is to illustrate the process of vaporization of different elements for various entry parameters. The numerical results for particles of various sizes and various zenith angles are treated in order to understand the changes in chemical composition that the particles undergo as they enter the atmosphere. Particles with large sizes (> few hundred μm) and high entry velocities (>16 km s-1) experience less time at peak temperatures compared to those that have lower velocities. Model calculations suggest that particles can survive with an entry velocity of 11 km s-1 and zenith angles (ZA) of 30°-90°, which accounts for ˜66% of the region where particles retain their identities. Our results suggest that the changes in chemical composition of MgO, SiO2, and FeO are not significant for an entry velocity of 11 km s-1 and sizes <300 μm, but the changes in these compositions become significant beyond this size, where FeO is lost to a major extent. However, at 16 km s-1 the changes in MgO, SiO2, and FeO are very intense, which is also reflected in Mg/Si, Fe/Si, Ca/Si, and Al/Si ratios, even for particles with a size of 100 μm. Beyond 400 μm particle sizes at 16 km s-1, most of the major elements are vaporized, leaving the refractory elements, Al and Ca, suspended in the troposphere.

  5. Flux induced growth of atmospheric nano-particles by organic vapors

    Directory of Open Access Journals (Sweden)

    J. Wang

    2012-09-01

    Full Text Available Atmospheric aerosols play critical roles in air quality, public health, and visibility. In addition, they strongly influence climate by scattering solar radiation and by changing the reflectivity and lifetime of clouds. One major but still poorly understood source of atmospheric aerosol is new particle formation, which consists of the formation of thermodynamically stable clusters from trace gas molecules (homogeneous nucleation followed by growth of these clusters to a detectable size (~3 nm. Because freshly nucleated clusters are most susceptible to loss due to high rate of coagulation with pre-existing aerosol population, the initial growth rate strongly influences the rate of new particle formation and ambient aerosol population. Whereas many field observations and modeling studies indicate that organics enhance the initial growth of the clusters and therefore new particle formation, thermodynamic considerations would suggest that the strong increase of equilibrium vapor concentration due to cluster surface curvature (Kelvin effect may prevent ambient organics from condensing on these small clusters. Here the initial condensational growth of freshly nucleated clusters is described as heterogeneous nucleation of organic molecules onto these clusters. We find that the strong gradient in cluster population with respect to its size lead to positive cluster number flux, and therefore driving the growth of clusters substantially smaller than the Kelvin diameter, conventionally considered as the minimum particle size that can be grown through condensation. The conventional approach neglects this contribution from the cluster concentration gradient, and underestimates the rate of new particle formation by a factor of up to 60.

  6. Flux induced growth of atmospheric nano-particles by organic vapors

    Science.gov (United States)

    Wang, J.; McGraw, R. L.; Kuang, C.

    2012-09-01

    Atmospheric aerosols play critical roles in air quality, public health, and visibility. In addition, they strongly influence climate by scattering solar radiation and by changing the reflectivity and lifetime of clouds. One major but still poorly understood source of atmospheric aerosol is new particle formation, which consists of the formation of thermodynamically stable clusters from trace gas molecules (homogeneous nucleation) followed by growth of these clusters to a detectable size (~3 nm). Because freshly nucleated clusters are most susceptible to loss due to high rate of coagulation with pre-existing aerosol population, the initial growth rate strongly influences the rate of new particle formation and ambient aerosol population. Whereas many field observations and modeling studies indicate that organics enhance the initial growth of the clusters and therefore new particle formation, thermodynamic considerations would suggest that the strong increase of equilibrium vapor concentration due to cluster surface curvature (Kelvin effect) may prevent ambient organics from condensing on these small clusters. Here the initial condensational growth of freshly nucleated clusters is described as heterogeneous nucleation of organic molecules onto these clusters. We find that the strong gradient in cluster population with respect to its size lead to positive cluster number flux, and therefore driving the growth of clusters substantially smaller than the Kelvin diameter, conventionally considered as the minimum particle size that can be grown through condensation. The conventional approach neglects this contribution from the cluster concentration gradient, and underestimates the rate of new particle formation by a factor of up to 60.

  7. Quantification of environmentally persistent free radicals and reactive oxygen species in atmospheric aerosol particles

    Science.gov (United States)

    Arangio, Andrea M.; Tong, Haijie; Socorro, Joanna; Pöschl, Ulrich; Shiraiwa, Manabu

    2016-10-01

    Fine particulate matter plays a central role in the adverse health effects of air pollution. Inhalation and deposition of aerosol particles in the respiratory tract can lead to the release of reactive oxygen species (ROS), which may cause oxidative stress. In this study, we have detected and quantified a wide range of particle-associated radicals using electron paramagnetic resonance (EPR) spectroscopy. Ambient particle samples were collected using a cascade impactor at a semi-urban site in central Europe, Mainz, Germany, in May-June 2015. Concentrations of environmentally persistent free radicals (EPFR), most likely semiquinone radicals, were found to be in the range of (1-7) × 1011 spins µg-1 for particles in the accumulation mode, whereas coarse particles with a diameter larger than 1 µm did not contain substantial amounts of EPFR. Using a spin trapping technique followed by deconvolution of EPR spectra, we have also characterized and quantified ROS, including OH, superoxide (O2-) and carbon- and oxygen-centered organic radicals, which were formed upon extraction of the particle samples in water. Total ROS amounts of (0.1-3) × 1011 spins µg-1 were released by submicron particle samples and the relative contributions of OH, O2-, C-centered and O-centered organic radicals were ˜ 11-31, ˜ 2-8, ˜ 41-72 and ˜ 0-25 %, respectively, depending on particle sizes. OH was the dominant species for coarse particles. Based on comparisons of the EPR spectra of ambient particulate matter with those of mixtures of organic hydroperoxides, quinones and iron ions followed by chemical analysis using liquid chromatography mass spectrometry (LC-MS), we suggest that the particle-associated ROS were formed by decomposition of organic hydroperoxides interacting with transition metal ions and quinones contained in atmospheric humic-like substances (HULIS).

  8. Hygroscopic growth of atmospheric aerosol particles and its relation to nucleation scavenging in clouds

    Energy Technology Data Exchange (ETDEWEB)

    Svenningsson, B.

    1997-11-01

    Aerosol particles in the atmosphere are important in several aspects. Some major aerosol constituents that are deposited in ecosystems are acidic or fertilizers and some minor or trace constituents are toxic. Aerosol particles are also involved in the earth`s radiation balance, both directly by scattering the sunlight and indirectly by influencing the clouds. All these effects are influenced by the interaction between the aerosol particles and water vapour. A tandem differential mobility analyser (TDMA) has been designed to measure hygroscopic growth, i.e. the particle diameter change due to uptake of water at well defined relative humidities below 100%. Tests of the instrument performance have been made using aerosol particles of pure inorganic salts. Three field experiments have been performed as parts of large fog and cloud experiments. Bimodal hygroscopic growth spectra were found: less-hygroscopic particles containing a few percent and more-hygroscopic particles around 50% by volume of hygroscopically active material. In general the fraction of less-hygroscopic particles decreases with particle size and it is larger in polluted continental aerosols than in remote background aerosols. This external mixing cannot be fully understood using present views on the formation of aerosols. Evidence or the importance of the external mixing on the cloud nucleating properties of the particles are found in comparisons between hygroscopic growth spectra for the total aerosol, the interstitial aerosol in clouds, and cloud drop residuals. Cloud condensation nuclei spectra, calculated using aerosol particle size distributions and hygroscopic growth spectra, in combination with information on the major inorganic ions are presented. These CCN spectra reveal for instance that the influence of less-hygroscopic particles on the cloud droplets increases with increasing peak supersaturation. The fraction of the particles that were scavenged to cloud drops, as a function of particle

  9. Pesticides in the atmosphere: a comparison of gas-particle partitioning and particle size distribution of legacy and current-use pesticides

    Science.gov (United States)

    Degrendele, C.; Okonski, K.; Melymuk, L.; Landlová, L.; Kukučka, P.; Audy, O.; Kohoutek, J.; Čupr, P.; Klánová, J.

    2016-02-01

    This study presents a comparison of seasonal variation, gas-particle partitioning, and particle-phase size distribution of organochlorine pesticides (OCPs) and current-use pesticides (CUPs) in air. Two years (2012/2013) of weekly air samples were collected at a background site in the Czech Republic using a high-volume air sampler. To study the particle-phase size distribution, air samples were also collected at an urban and rural site in the area of Brno, Czech Republic, using a cascade impactor separating atmospheric particulates according to six size fractions. Major differences were found in the atmospheric distribution of OCPs and CUPs. The atmospheric concentrations of CUPs were driven by agricultural activities while secondary sources such as volatilization from surfaces governed the atmospheric concentrations of OCPs. Moreover, clear differences were observed in gas-particle partitioning; CUP partitioning was influenced by adsorption onto mineral surfaces while OCPs were mainly partitioning to aerosols through absorption. A predictive method for estimating the gas-particle partitioning has been derived and is proposed for polar and non-polar pesticides. Finally, while OCPs and the majority of CUPs were largely found on fine particles, four CUPs (carbendazim, isoproturon, prochloraz, and terbuthylazine) had higher concentrations on coarse particles ( > 3.0 µm), which may be related to the pesticide application technique. This finding is particularly important and should be further investigated given that large particles result in lower risks from inhalation (regardless the toxicity of the pesticide) and lower potential for long-range atmospheric transport.

  10. Protective effects of pulmonary epithelial lining fluid on oxidative stress and DNA single-strand breaks caused by ultrafine carbon black, ferrous sulphate and organic extract of diesel exhaust particles

    Energy Technology Data Exchange (ETDEWEB)

    Chuang, Hsiao-Chi [School of Respiratory Therapy, College of Medicine, Taipei Medical University, Taipei, Taiwan (China); Division of Pulmonary Medicine, Department of Internal Medicine, Shuang Ho Hospital, Taipei Medical University, Taipei, Taiwan (China); Cheng, Yi-Ling; Lei, Yu-Chen [Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, Taipei, Taiwan (China); Chang, Hui-Hsien [Institute of Environmental Health, College of Public Health, National Taiwan University, Taipei, Taiwan (China); Cheng, Tsun-Jen, E-mail: tcheng@ntu.edu.tw [Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, Taipei, Taiwan (China); Department of Public Health, College of Public Health, National Taiwan University, Taipei, Taiwan (China)

    2013-02-01

    Pulmonary epithelial lining fluid (ELF) is the first substance to make contact with inhaled particulate matter (PM) and interacts chemically with PM components. The objective of this study was to determine the role of ELF in oxidative stress, DNA damage and the production of proinflammatory cytokines following physicochemical exposure to PM. Ultrafine carbon black (ufCB, 15 nm; a model carbonaceous core), ferrous sulphate (FeSO{sub 4}; a model transition metal) and a diesel exhaust particle (DEP) extract (a model organic compound) were used to examine the acellular oxidative potential of synthetic ELF and non-ELF systems. We compared the effects of exposure to ufCB, FeSO{sub 4} and DEP extract on human alveolar epithelial Type II (A549) cells to determine the levels of oxidative stress, DNA single-strand breaks and interleukin-8 (IL-8) production in ELF and non-ELF systems. The effects of ufCB and FeSO{sub 4} on the acellular oxidative potential, cellular oxidative stress and DNA single-strand breakage were mitigated significantly by the addition of ELF, whereas there was no decrease following treatment with the DEP extract. There was no significant effect on IL-8 production following exposure to samples that were suspended in ELF/non-ELF systems. The results of the present study indicate that ELF plays an important role in the initial defence against PM in the pulmonary environment. Experimental components, such as ufCB and FeSO{sub 4}, induced the production of oxidative stress and led to DNA single-strand breaks, which were moderately prevented by the addition of ELF. These findings suggest that ELF plays a protective role against PM-driven oxidative stress and DNA damage. -- Highlights: ► To determine the role of ELF in ROS, DNA damage and IL-8 after exposure to PM. ► ufCB, FeSO{sub 4} and DEP extract were used to examine the protective effects of ELF. ► PM-driven oxidative stress and DNA single-strand breakage were mitigated by ELF. ► The findings

  11. COMPASS – COMparative Particle formation in the Atmosphere using Simulation chamber Study techniques

    Directory of Open Access Journals (Sweden)

    B. Bonn

    2013-06-01

    Full Text Available The anthropogenic influence on climate and environment has increased strongly since industrialization about 150 yr ago. The consequences for the atmosphere became more and more apparent and nowadays affect our life quality on Earth progressively. Because of that it is very important to understand the atmospheric processes, on which these effects are based on, in detail. In this study we report the set-up of a novel twin chamber technique that uses the comparative method and establishes an appropriate connection of atmospheric and laboratory methods to broaden the tools for investigations. It is designed to study the impact of certain parameters and gases on ambient processes such as particle formation online and can be applied in a large variety of conditions. The characterisation of both chambers proved that both chambers operate identically with a residence time (xT (COMPASS 1 = 26.5 ± 0.3 min and xT (COMPASS 2 = 26.6 ± 0.4 min at a typical flow rate of 15 L min−1 and a deposition rate (1.6 ± 0.8 × 10−5 s−1. Comparison measurement showed no significant differences. Therefore operation under atmospheric conditions is trustworthy. To indicate the applicability and the benefit of the system a set of experiments was conducted at different conditions, i.e. urban and remote, enhancing ozone and terpenes as well as reducing sunlight. In the ozone enhanced ambient particle number and volume increased substantially at urban and remote conditions in a different strength. Solar radiation displayed a clear positive effect on particle number as well as terpene addition did at remote conditions. Therefore the system is a useful tool to investigate local precursors, the details of ambient particle formation at surface locations as well as future feedback processes.

  12. Optical propagation in linear media atmospheric gases and particles, solid-state components, and water

    CERN Document Server

    Thomas, Michael E

    2006-01-01

    PART I: Background Theory and Measurement. 1. Optical Electromagnetics I. 2. Optical Electromagnetics II. 3. Spectroscopy of Matter. 4. Electrodynamics I: Macroscopic Interaction of Light and Matter. 5. Electrodynamics II: Microscopic Interaction of Light and Matter. 6. Experimental Techniques. PART II: Practical Models for Various Media. 7. Optical Propagation in Gases and the Atmosphere of the Earth. 8. Optical Propagation in Solids. 9. Optical Propagation in Liquids. 10. Particle Absorption and Scatter. 11. Propagation Background and Noise

  13. Preservation of amorphous ultrafine material: A proposed proxy for slip during recent earthquakes on active faults

    Science.gov (United States)

    Hirono, Tetsuro; Asayama, Satoru; Kaneki, Shunya; Ito, Akihiro

    2016-11-01

    The criteria for designating an “Active Fault” not only are important for understanding regional tectonics, but also are a paramount issue for assessing the earthquake risk of faults that are near important structures such as nuclear power plants. Here we propose a proxy, based on the preservation of amorphous ultrafine particles, to assess fault activity within the last millennium. X-ray diffraction data and electron microscope observations of samples from an active fault demonstrated the preservation of large amounts of amorphous ultrafine particles in two slip zones that last ruptured in 1596 and 1999, respectively. A chemical kinetic evaluation of the dissolution process indicated that such particles could survive for centuries, which is consistent with the observations. Thus, preservation of amorphous ultrafine particles in a fault may be valuable for assessing the fault’s latest activity, aiding efforts to evaluate faults that may damage critical facilities in tectonically active zones.

  14. Lidar remote sensing of laser-induced incandescence on light absorbing particles in the atmosphere.

    Science.gov (United States)

    Miffre, Alain; Anselmo, Christophe; Geffroy, Sylvain; Fréjafon, Emeric; Rairoux, Patrick

    2015-02-09

    Carbon aerosol is now recognized as a major uncertainty on climate change and public health, and specific instruments are required to address the time and space evolution of this aerosol, which efficiently absorbs light. In this paper, we report an experiment, based on coupling lidar remote sensing with Laser-Induced-Incandescence (LII), which allows, in agreement with Planck's law, to retrieve the vertical profile of very low thermal radiation emitted by light-absorbing particles in an urban atmosphere over several hundred meters altitude. Accordingly, we set the LII-lidar formalism and equation and addressed the main features of LII-lidar in the atmosphere by numerically simulating the LII-lidar signal. We believe atmospheric LII-lidar to be a promising tool for radiative transfer, especially when combined with elastic backscattering lidar, as it may then allow a remote partitioning between strong/less light absorbing carbon aerosols.

  15. Preparation of ultrafine Ti (C, N)-based cermet using oxygen-rich powders

    Institute of Scientific and Technical Information of China (English)

    FENG Ping; HE Yue-hui; XIONG Wei-hao; XIAO Yi-feng

    2005-01-01

    The availability using oxygen-rich powders to prepare ultrafine Ti(C,N)-based cermets was investigated. The deoxidation process, denitrification phenomenon and the effect of deoxidation on microstructure and mechanical properties of sintered samples were discussed, respectively. The results show that oxygen in the samples prepared even with high oxygen contained in starting powders can be almost completely cleaned away through suitable sintering process. The ultrafine oxygen-rich powders have a significant effect on microstructure, which promotes the formation of white core phase. A ultrafine Ti(C,N)-based cermet with mean particle size of 0. 30 μm, uniform microstructure and excellent mechanical properties is successfully prepared. It is also found that there exists severe denitrification phenomenon in the preparation process of ultrafine Ti(C,N)-based cermet.

  16. Particle Densities of the Atmospheric-Pressure Argon Plasmas Generated by the Pulsed Dielectric Barrier Discharges

    Science.gov (United States)

    Pan, Jie; Li, Li; Wang, Yunuan; Xiu, Xianwu; Wang, Chao; Song, Yuzhi

    2016-11-01

    Atmospheric-pressure argon plasmas have received increasing attention due to their high potential in many industrial and biomedical applications. In this paper, a 1-D fluid model is used for studying the particle density characteristics of the argon plasmas generated by the pulsed dielectric barrier discharges. The temporal evolutions of the axial particle density distributions are illustrated, and the influences of changing the main discharge conditions on the averaged particle densities are researched by independently varying the various discharge conditions. The calculation results show that the electron density and the ion density reach two peaks near the momentary cathodes during the rising and the falling edges of the pulsed voltage. Compared with the charged particle densities, the densities of the resonance state atom Arr and the metastable state atom Arm have more uniform axial distributions, reach higher maximums and decay more slowly. During the platform of the pulsed voltage and the time interval between the pulses, the densities of the excited state atom Ar* are far lower than those of the Arr or the Arm. The averaged particle densities of the different considered particles increase with the increases of the amplitude and the frequency of the pulsed voltage. Narrowing the discharge gap and increasing the relative dielectric constant of the dielectric also contribute to the increase of the averaged particle densities. The effects of reducing the discharge gap distance on the neutral particle densities are more significant than the influences on the charged particle densities. supported by Natural Science Foundation of Shandong Province, China (No. ZR2015AQ008), and Project of Shandong Province Higher Educational Science and Technology Program of China (No. J15LJ04)

  17. Plasma synthesis and characterization of ultrafine SiC

    Energy Technology Data Exchange (ETDEWEB)

    Vogt, G.J.; Phillips, D.S.; Taylor, T.N.

    1986-01-01

    Ultrafine SiC powders have been prepared by gas phase synthesis from silane and methane in an argon thermal rf-plasma. Bulk properties of the powders were determined by elemental analysis, x-ray diffractin, helium pycnometry, and BET surface area measurements. The near-surface composition and structure of the particles were examined by x-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). In addition to free silicon and carbon particles in the powders, free carbon and various silicon/carbon/oxygen species were found on the surface of the SiC particles.

  18. Influence of radioactivity on surface charging and aggregation kinetics of particles in the atmosphere.

    Science.gov (United States)

    Kim, Yong-Ha; Yiacoumi, Sotira; Lee, Ida; McFarlane, Joanna; Tsouris, Costas

    2014-01-01

    Radioactivity can influence surface interactions, but its effects on particle aggregation kinetics have not been included in transport modeling of radioactive particles. In this research, experimental and theoretical studies have been performed to investigate the influence of radioactivity on surface charging and aggregation kinetics of radioactive particles in the atmosphere. Radioactivity-induced charging mechanisms have been investigated at the microscopic level, and heterogeneous surface potential caused by radioactivity is reported. The radioactivity-induced surface charging is highly influenced by several parameters, such as rate and type of radioactive decay. A population balance model, including interparticle forces, has been employed to study the effects of radioactivity on particle aggregation kinetics in air. It has been found that radioactivity can hinder aggregation of particles because of similar surface charging caused by the decay process. Experimental and theoretical studies provide useful insights into the understanding of transport characteristics of radioactive particles emitted from severe nuclear events, such as the recent accident of Fukushima or deliberate explosions of radiological devices.

  19. Hydrostatic Simulation of Earth's Atmospheric Gas Using Multi-particle Collision Dynamics

    CERN Document Server

    Pattisahusiwa, Asis; Virid, Sparisoma

    2015-01-01

    Multi-particle collision dynamics (MPCD) is a mesoscopic simulation method to simulate fluid particle-like flows. MPCD has been widely used to simulate various problems in condensed matter. In this study, hydrostatic behavior of gas in the Earth's atmospheric layer is simulated by using MPCD method. The simulation is carried out by assuming the system under ideal state and is affected only by gravitational force. Gas particles are homogeneous and placed in 2D box. Interaction of the particles with the box is applied through implementation of boundary conditions (BC). Periodic BC is applied on the left and the right side, specular reflection on the top side, while bounce-back on the bottom side. Simulation program is executed in Arch Linux and running in notebook with processor Intel i5 @2700 MHz with 10 GB DDR3 RAM. The results show behaviors of the particles obey kinetic theory for ideal gas when gravitational acceleration value is proportional to the particle mass. Density distribution as a function of alti...

  20. Characterization of inorganic atmospheric particles in air quality program with SEM, TEM and XAS

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez L, R. [Centro de Estudios Superiores del Estado de Sonora Ley Federal del Trabajo Final s/n, Col. Apolo, 83100 Hermosillo, Sonora (Mexico); Esparza P, H. [Centro de Investigacion en Materiales Avanzados S. C. Miguel de Chihuahua No. 120, Complejo Industrial Chihuahua, 31109 Chihuahua (Mexico); Duarte M, A. [Departamento de Fisica, Universidad de Sonora, Blvd. Luis Encinas y Rosales, s/n. 83000 Hermosillo, Sonora (Mexico)

    2007-07-01

    Physical and chemical characterization of inorganic atmospheric particle samples collected on TSP and PM10 filters from January 2003 through December 2005 from three zones within the city of Hermosillo, Sonora; using Transmission Electron Microscopy, Scanning combined with EDS and Stanford University's Synchrotron X-Ray. The sample preparation for electron microscopy was deposited as an alcohol suspension using a sample holder. The different elements found amongst individual particles were Al, Ba, Bi, Br, Ca, Ce, Cl, Cr, Cu, Fe, K, La, Mn, Mg, Na, P, Pb, S, Si, Ti, U, V, W, Zn and Zr. These particles' morphology and chemical composition, illustrate an abundance of natural elements within the zone. However some of the elements present are directly related with human activities, and are of much interest from the public health and environmental perspectives. (Author)

  1. Light Induced Degradation of Eight Commonly Used Pesticides Adsorbed on Atmospheric Particles: Kinetics and Product Study

    Science.gov (United States)

    Socorro, J.; Durand, A.; Gligorovski, S.; Wortham, H.; Quivet, E.

    2014-12-01

    Pesticides are widely used all over the world whether in agricultural production or in non-agricultural settings. They may pose a potential human health effects and environmental risks due to their physico-chemical properties and their extensive use which is growing every year. Pesticides are found in the atmosphere removed from the target area by volatilization or wind erosion, and carried over long distances. These compounds are partitioned between the gaseous and particulate atmospheric phases. The increasingly used pesticides are semi-volatile compounds which are usually adsorbed on the surface of the atmospheric particles. These pesticides may undergo chemical and photo-chemical transformation. New compounds may then be formed that could be more hazardous than the primary pesticides. The atmospheric fate and lifetime of adsorbed pesticides on particles are controlled by the these (photo)chemical processes. However, there is a lack of kinetic data regarding the pesticides in the particle phase. This current work focuses on the photolytic degradation of commonly used pesticides in particulate phase. It aims at estimating the photolytic rates and thus the lifetimes of pesticides adsorbed on silica particles as a proxy of atmospheric particles. The following eight commonly used pesticides, cyprodinil, deltamethrin, difenoconazole, fipronil, oxadiazon, pendimethalin, permethrin, tetraconazole, were chosen because of their physico-chemical properties. The photolysis rates of tetraconazole and permethrin were extremely slow ≤ 1.2 · 10-6 s-1. The photolysis rates for the other pesticides were determined in the range of: (5.9 ± 0.3) · 10-6 fipronil. Finally, the identification of the surface products upon light irradiation was performed, using GC-(QqQ)-MS/MS and LC-(Q-IMS-ToF)-MS/MS. The potentially formed gas-phase products during these photolysis processes were followed continuously and on-line by PTR-ToF-MS. We hope that the obtained results from this study

  2. Volatility of mixed atmospheric humic-like substances and ammonium sulfate particles

    Science.gov (United States)

    Nie, Wei; Hong, Juan; Häme, Silja A. K.; Ding, Aijun; Li, Yugen; Yan, Chao; Hao, Liqing; Mikkilä, Jyri; Zheng, Longfei; Xie, Yuning; Zhu, Caijun; Xu, Zheng; Chi, Xuguang; Huang, Xin; Zhou, Yang; Lin, Peng; Virtanen, Annele; Worsnop, Douglas R.; Kulmala, Markku; Ehn, Mikael; Yu, Jianzhen; Kerminen, Veli-Matti; Petäjä, Tuukka

    2017-03-01

    The volatility of organic aerosols remains poorly understood due to the complexity of speciation and multiphase processes. In this study, we extracted humic-like substances (HULIS) from four atmospheric aerosol samples collected at the SORPES station in Nanjing, eastern China, and investigated the volatility behavior of particles at different sizes using a Volatility Tandem Differential Mobility Analyzer (VTDMA). In spite of the large differences in particle mass concentrations, the extracted HULIS from the four samples all revealed very high-oxidation states (O : C > 0.95), indicating secondary formation as the major source of HULIS in Yangtze River Delta (YRD). An overall low volatility was identified for the extracted HULIS, with the volume fraction remaining (VFR) higher than 55 % for all the regenerated HULIS particles at the temperature of 280 °C. A kinetic mass transfer model was applied to the thermodenuder (TD) data to interpret the observed evaporation pattern of HULIS, and to derive the mass fractions of semi-volatile (SVOC), low-volatility (LVOC) and extremely low-volatility components (ELVOC). The results showed that LVOC and ELVOC dominated (more than 80 %) the total volume of HULIS. Atomizing processes led to a size-dependent evaporation of regenerated HULIS particles, and resulted in more ELVOC in smaller particles. In order to understand the role of interaction between inorganic salts and atmospheric organic mixtures in the volatility of an organic aerosol, the evaporation of mixed samples of ammonium sulfate (AS) and HULIS was measured. The results showed a significant but nonlinear influence of ammonium sulfate on the volatility of HULIS. The estimated fraction of ELVOC in the organic part of the largest particles (145 nm) increased from 26 %, in pure HULIS samples, to 93 % in 1 : 3 (mass ratio of HULIS : AS) mixed samples, to 45 % in 2 : 2 mixed samples, and to 70 % in 3 : 1 mixed samples, suggesting that the interaction with ammonium sulfate

  3. Impact of cosmic rays and solar energetic particles on the Earth’s ionosphere and atmosphere

    Directory of Open Access Journals (Sweden)

    Mateev Lachezar

    2013-03-01

    Full Text Available A brief review of the study during COST Action ES0803 of effects due to cosmic rays (CR and solar energetic particles (SEP in the ionosphere and atmosphere is presented. Models CORIMIA (COsmic Ray Ionization Model for Ionosphere and Atmosphere and application of CORSIKA (COsmic Ray SImulations for KAscade code are considered. They are capable to compute the cosmic ray ionization profiles at a given location, time, solar and geomagnetic activity. Intercomparison of the models, as well as comparison with direct measurements of the atmospheric ionization, validates their applicability for the entire atmosphere and for the different levels of the solar activity. The effects of CR and SEP can be very strong locally in the polar cap regions, affecting the physical-chemical and electrical properties of the ionosphere and atmosphere. Contributions here were also made by the anomalous CR, whose ionization is significant at high geomagnetic latitudes (above 65°–70°. Several recent achievements and application of CR ionization models are briefly presented. This work is the output from the SG 1.1 of the COST ES0803 action (2008–2012 and the emphasis is given on the progress achieved by European scientists involved in this collaboration.

  4. Particle number size distribution and new particle formation:New characteristics during the special pollution control period in Beijing

    Institute of Scientific and Technical Information of China (English)

    Jian Gao; Fahe Chai; Tao Wang; Shulan Wang; Wenxing Wang

    2012-01-01

    New particle formation is a key process in shaping the size distribution of aerosols in the atmosphere.We present here the measurement results of number and size distribution of aerosol particles (10-10000 nm in diameter) obtained in the summer of 2008,at a suburban site in Beijing,China.We firstly reported the pollution level,particle number size distribution,diurnal variation of the particle number size distribution and then introduced the characteristics of the particle formation processes.The results showed that the number concentration of ultrafine particles was much lower than the values measured in other urban or suburban areas in previous studies.Sharp increases of ultrafine particle count were frequently observed at noon.An examination of the diurnal pattern suggested that the burst of ultrafine particles was mainly due to new particle formation promoted by photochemical processes.In addition,high relative humidity was a key factor driving the growth of the particles in the afternoon.During the 2-month observations,new particle formation from homogeneous nucleation was observed for 42.7% of the study period.The average growth rate of newly formed particles was 3.2 nm/hr,and varied from 1.2 to 8.0 nm/hr.The required concentration of condensable vapor was 4.4 × 107 cm-3,and its source rate was 1.2 × 106 cm-3sec-1.Further calculation on the source rate of sulphuric acid vapor indicated that the average participation of sulphuric acid to particle growth rates was 28.7%.

  5. Energy Transport Effects in Flaring Atmospheres Heated by Mixed Particle Beams

    Science.gov (United States)

    Zharkova, Valentina; Zharkov, Sergei; Macrae, Connor; Druett, Malcolm; Scullion, Eamon

    2016-07-01

    We investigate energy and particle transport in the whole flaring atmosphere from the corona to the photosphere and interior for the flaring events on the 1st July 2012, 6 and 7 September 2011 by using the RHESSI and SDO instruments as well as high-resolution observations from the Swedish 1-metre Solar Telescope (SST3) CRISP4 (CRisp Imaging Spectro-polarimeter). The observations include hard and soft X-ray emission, chromospheric emission in both H-alpha 656.3 nm core and continuum, as well as, in the near infra-red triplet Ca II 854.2 nm core and continuum channels and local helioseismic responses (sunquakes). The observations are compared with the simulations of hard X-ray emission and tested by hydrodynamic simulations of flaring atmospheres of the Sun heated by mixed particle beams. The temperature, density and macro-velocity variations of the ambient atmospheres are calculated for heating by mixed beams and the seismic response of the solar interior to generation of supersonic shocks moving into the solar interior. We investigate the termination depths of these shocks beneath the quiet photosphere levels and compare them with the parameters of seismic responses in the interior, or sunquakes (Zharkova and Zharkov, 2015). We also present an investigation of radiative conditions modelled in a full non-LTE approach for hydrogen during flare onsets with particular focus on Balmer and Paschen emission in the visible, near UV and near IR ranges and compare them with observations. The links between different observational features derived from HXR, optical and seismic emission are interpreted by different particle transport models that will allow independent evaluation of the particle transport scenarios.

  6. Formation of highly porous aerosol particles by atmospheric freeze-drying in ice clouds.

    Science.gov (United States)

    Adler, Gabriela; Koop, Thomas; Haspel, Carynelisa; Taraniuk, Ilya; Moise, Tamar; Koren, Ilan; Heiblum, Reuven H; Rudich, Yinon

    2013-12-17

    The cycling of atmospheric aerosols through clouds can change their chemical and physical properties and thus modify how aerosols affect cloud microphysics and, subsequently, precipitation and climate. Current knowledge about aerosol processing by clouds is rather limited to chemical reactions within water droplets in warm low-altitude clouds. However, in cold high-altitude cirrus clouds and anvils of high convective clouds in the tropics and midlatitudes, humidified aerosols freeze to form ice, which upon exposure to subsaturation conditions with respect to ice can sublimate, leaving behind residual modified aerosols. This freeze-drying process can occur in various types of clouds. Here we simulate an atmospheric freeze-drying cycle of aerosols in laboratory experiments using proxies for atmospheric aerosols. We find that aerosols that contain organic material that undergo such a process can form highly porous aerosol particles with a larger diameter and a lower density than the initial homogeneous aerosol. We attribute this morphology change to phase separation upon freezing followed by a glass transition of the organic material that can preserve a porous structure after ice sublimation. A porous structure may explain the previously observed enhancement in ice nucleation efficiency of glassy organic particles. We find that highly porous aerosol particles scatter solar light less efficiently than nonporous aerosol particles. Using a combination of satellite and radiosonde data, we show that highly porous aerosol formation can readily occur in highly convective clouds, which are widespread in the tropics and midlatitudes. These observations may have implications for subsequent cloud formation cycles and aerosol albedo near cloud edges.

  7. Polynuclear aromatic hydrocarbon degradation by heterogeneous reactions with N 2O 5 on atmospheric particles

    Science.gov (United States)

    Kamens, Richard M.; Guo, Jiazhen; Guo, Zhishi; McDow, Stephen R.

    The degradation of particulate polynuclear aromatic hydrocarbons (PAH) on atmospheric soot particles in the presence of gas phase dinitrogen pentoxide (N 2O 5) was explored. Dilute diesel and wood soot particles containing PAH were reacted with˜10ppm of N 2O 5 in a 200 ℓ continuous stirred tank reactor (CSTR). To provide a stable source of particles for reaction in the CSTR, diesel or wood soot particles were injected at night into a 25 m 3 Teflon outdoor chamber. The large chamber served as a reservoir for the feed aerosol, and the aerosol could then be introduced at a constant flow rate into the CSTR. PAH-N 2O 5 heterogeneous rate constants for wood soot at 15°C ranged from2 × 10 -18to5 × 10 -18 cm 3 molecules -1 s -1. For diesel soot the rate constants at 16°C were higher and ranged from5 × 10 -18to30 × 10 -18 cm 3 molecules -1 s -1. Comparisons with other studies suggest that sunlight is the most important factor which influences PAH decay. This is followed by ozone, NO 2, N 2O 5 and nitric acid. The rate constants of nitro-PAH formation from a parent PAH and N 2O 5 were of the order of1 × 10 -19-1 × 10 -18 molecules -1s -1. The uncertainty associated with all of these rate constants is± a factor of 3. Given, however, the small magnitude of the rate constants and the low levels of N 2O 5 present in the atmosphere, we concluded that PAH heterogeneous reactions with gas phase N 2O 5 degrade particle-bound PAH or to form nitro-PAH from PAH are not very important. (Direct application of the specific rate constants derived in this study to ambient atmospheres should not be undertaken unless the ambient particle size distributions and chemical composition of the particles are similar to the ones reported in this study.)

  8. A realtime, online automated system for measurement of Phosphate ions in atmospheric particles

    Science.gov (United States)

    Violaki, Kalliopi; Fang, Ting; Mihalopoulos, Nikos; Weber, Rodney James; Nenes, Athanasios

    2016-04-01

    Primary productivity of continental and marine ecosystems is often limited or co-limited by phosphorus. Of particular interest is the role of phosphorus in marine primary productivity, owing to its potential for affecting the concentration of atmospheric carbon dioxide. The atmosphere is considered a principal source of externally-supplied nutrients for large areas of the surface ocean, and oligotrophic open oceans in particular. Atmospheric inorganic P species (e.g. mono- or diprotonated orthophosphate) comprise the most bioavailable P form, and have been studied for many decades. Nevertheless, there are very large uncertainties in the phosphate biogeochemical budget due to the lack of observations and the poor match of the model to observations. This study presents a novel automated on-line, real-time analytical method for the analysis of water-soluble PO4-3 ions in atmospheric particles. The instrumentation consists of a particle-into-liquid sampler (PILS) coupled with a reaction coil to allow reagents to interact with the PILS liquid flow; the composite flow is then introduced into a mini spectrophotometer, which is equipped with a long path length of 250cm Liquid Wavequide Capillary Cell (LWCC), achieving low detection limit. This new system overcomes the limitations on detection and time resolution, as the configuration presented allows for measurement with 8 minute resolution. The data, when combined with routine PILS-IC or aerosol mass spectrometry, allows for an unprecedented insight towards the drivers of phosphate solubility and its relation to acidification from atmospheric acids. We present results for concentration of PM2.5 PO4-3 in Atlanta Georgia for a 2 month period (February-March, 2015) and the Eastern Mediterranean and its relation to aerosol acidity and other meteorological parameters. The results are discussed together with future directions towards optimized performance during long periods of operation.

  9. Removal of ultrafine particles from indoor environment

    DEFF Research Database (Denmark)

    Ardkapan, Siamak Rahimi

    technologies in order to improve indoor air quality. The objective of this study is to determine the effectiveness of portable air cleaners and to investigate the approaches of using these devices aiming at reducing the concentration of UFPs in the indoor environment. Experimental investigations...... and computational fluid dynamics (CFD) simulations were performed parallel in order to investigate the possibilities, limitations and possible applications to reach this aim. The Danish market was searched for portable air cleaners to be evaluated in the experiments. Five technologies were selected: Non Thermal...

  10. EFFECTS OF HEAT TREATMENT ON STRUCTURE AND PROPERTIES OF ULTRAFINE K—Co—Mo CATTALYSTS

    Institute of Scientific and Technical Information of China (English)

    BAOJun; BIANGuo-Zhu; FuYi-lu; HUTian-dou; LIUTao

    2001-01-01

    Co-Mo ultrafine particles were prepared by sol-gel method with citric acid as a complexant.The obtained dried gel was calcined in air and argon atmospheres,respectively.After promoting by K2CO3 and sulifiding,the two catalysts were single CoMoO4 crystallites with average size of 60nm.For the sample treated in argon,the main species in the sample were CoMoO3,besides,some Co-MoO4 existed,and the average size was about 20nm.These results indicated that the decomposition of citric acid reduced the CoMoO4 species and decreased the particle size remarkalby.BET measurements showed that,trating the dried gel in argon,the obtained Co-Mo particle and corresxponding sulifded sample possessed a larger surface area.For the sulfided catalysts,MoS2 and EXAFS results indicated that the sulfided sample whose precursor treated in argon possessed smaller average size.The catalytic activity measurement showed that the decrease of the particle sizes resulted in better properties for mixed alcohol synthesis.

  11. 钙钛矿型LaCOO3和LaMnO3超细粒子的制备%PREPARATION OF LaCoO3 AND LaMnO3 ULTRA-FINE PARTICLES WITH PEROVSKITE STRUCTURE

    Institute of Scientific and Technical Information of China (English)

    刘源

    2000-01-01

    Ultra-fine particles of LaCoOa and LaMnOa with perovskite structure were prepared by way of coprecipitation. Characteristics and size of sample particles are observed and measured by use of XRD and TEM. The influence of ethanol functioning as a dispersant on the texture and structure of samples is studied.%以共沉淀法制备出了钙钛型结构的稀土复合氧化物LaMnO3和LaCoO3超 细粒子,采用X-射线衍射和透射电镜测试了所得样品的物相和颗粒大小,考察了 制备过程中乙醇作为分散剂的影响.

  12. Clustering Dynamics of Ultra-fine Particulate Systems

    Science.gov (United States)

    Dutt, Meenakshi; Elliott, James

    2008-03-01

    Length scales of particles and their surrounding medium strongly determines the nature of their interactions with one another and their responses to external fields. We are interested in systems of ultrafine particles (0.1 - 1.0 micron) such as volcanic ash, solid aerosols, or fine powders for pharmaceutical ihalation applications. We develop a numerical model for these systems using the Derjaguin-Muller-Toporov (DMT) adhesion theory along with the van der Waals attraction between the particles and their contact mechanical interactions. We study the dynamics of these systems in the absence and presence of gravity by controlling the particle size, and thereby, the surface properties of the particles. The high surface energies of these particles causes them to agglomerate as they gravitationally settle. We explore their internal structure as a function of their particle size.

  13. Concentration and size distribution of particulate oxalate in marine and coastal atmospheres - Implication for the increased importance of oxalate in nanometer atmospheric particles

    Science.gov (United States)

    Guo, Tianfeng; Li, Kai; Zhu, Yujiao; Gao, Huiwang; Yao, Xiaohong

    2016-10-01

    In literature, particulate oxalate has been widely studied in the total suspended particles (TSP), particles 100 nm. In this article, we measured oxalate's concentrations in size-segregated atmospheric particles down to 10 nm or 56 nm during eight campaigns performed at a semi-urban coastal site, over the marginal seas of China and from the marginal seas to the northwest Pacific Ocean (NWPO) in 2012-2015. When the sum of the oxalate's concentration in particles pollution event. Mode analysis results of particulate oxalate and the correlation between oxalate and sulfate suggested that the elevated concentrations of oxalate in PM10 were mainly related to enhanced in-cloud formation of oxalate via anthropogenic precursors. Size distribution data in the total of 136 sets of samples also showed approximately 80% of particulate oxalate's mass existing in atmospheric particles >100 nm. Consistent with previous studies, particulate oxalate in particles >100 nm was a negligible ionic component when comparing to particulate SO42- in the same size range. However, the mole ratios of oxalate/sulfate in particles 100 nm atmospheric particles such as PM2.5, PM10, TSP, etc.

  14. On the formation of sulphuric acid – amine clusters in varying atmospheric conditions and its influence on atmospheric new particle formation

    Directory of Open Access Journals (Sweden)

    I. K. Ortega

    2012-10-01

    Full Text Available Sulphuric acid is a key component in atmospheric new particle formation. However, sulphuric acid alone does not form stable enough clusters to initiate particle formation in atmospheric conditions. Strong bases, such as amines, have been suggested to stabilize sulphuric acid clusters and thus participate in particle formation. We modelled the formation rate of clusters with two sulphuric acid and two amine molecules (JA2B2 at varying atmospherically relevant conditions with respect to concentrations of sulphuric acid ([H2SO4], dimethylamine ([DMA] and trimethylamine ([TMA], temperature and relative humidity (RH. We also tested how the model results change if we assume that the clusters with two sulphuric acid and two amine molecules would act as seeds for heterogeneous nucleation of organic vapours (other than amines with higher atmospheric concentrations than sulphuric acid. The modelled formation rates JA2B2 were functions of sulphuric acid concentration with close to quadratic dependence, which is in good agreement with atmospheric observations of the connection between the particle formation rate and sulphuric acid concentration. The coefficients KA2B2 connecting the cluster formation rate and sulphuric acid concentrations as JA2B2=KA2B2[H2SO4]2 turned out to depend also on amine concentrations, temperature and relative humidity. We compared the modelled coefficients KA2B2 with the corresponding coefficients calculated from the atmospheric observations (Kobs from environments with varying temperatures and levels of anthropogenic influence. By taking into account the modelled behaviour of JA2B2 as a function of [H2SO4], temperature and RH, the atmospheric particle formation rate was reproduced more closely than with the traditional semi-empirical formulae based on sulphuric acid concentration only. The formation rates of clusters with two sulphuric acid and two amine molecules with different amine compositions (DMA or TMA or one of both had

  15. Measurements of the mass absorption cross section of atmospheric soot particles using Raman spectroscopy

    Science.gov (United States)

    Nordmann, S.; Birmili, W.; Weinhold, K.; Müller, K.; Spindler, G.; Wiedensohler, A.

    2013-11-01

    Soot particles are a major absorber of shortwave radiation in the atmosphere. The mass absorption cross section is an essential quantity to describe this light absorption process. This work presents new experimental data on the mass absorption cross section of soot particles in the troposphere over Central Europe. Mass absorption cross sections were derived as the ratio between the light absorption coefficient determined by multiangle absorption photometry (MAAP) and the soot mass concentration determined by Raman spectroscopy. The Raman method is sensitive to graphitic structures present in the particle samples and was calibrated in the laboratory using Printex®90 model particles. Mass absorption cross sections were determined for a number of seven observation sites, ranging between 3.9 and 7.4 m2 g-1depending on measurement site and observational period. The highest values were found in a continentally aged air mass in winter, where soot particles were assumed to be mainly internally mixed. Our values are in the lower range of previously reported values, possibly due to instrumental differences to the former photometer and mass measurements. Overall, a value of 5.3m2 g-1from orthogonal regression over all samples is considered to be representative for the soot mass absorption cross section in the troposphere over Central Europe.

  16. Dispersion of aerosol particles in the free atmosphere using ensemble forecasts

    Directory of Open Access Journals (Sweden)

    T. Haszpra

    2013-10-01

    Full Text Available The dispersion of aerosol particle pollutants is studied using 50 members of an ensemble forecast in the example of a hypothetical free atmospheric emission above Fukushima over a period of 2.5 days. Considerable differences are found among the dispersion predictions of the different ensemble members, as well as between the ensemble mean and the deterministic result at the end of the observation period. The variance is found to decrease with the particle size. The geographical area where a threshold concentration is exceeded in at least one ensemble member expands to a 5–10 times larger region than the area from the deterministic forecast, both for air column "concentration" and in the "deposition" field. We demonstrate that the root-mean-square distance of any particle from its own clones in the ensemble members can reach values on the order of one thousand kilometers. Even the centers of mass of the particle cloud of the ensemble members deviate considerably from that obtained by the deterministic forecast. All these indicate that an investigation of the dispersion of aerosol particles in the spirit of ensemble forecast contains useful hints for the improvement of risk assessment.

  17. Simulation of cold atmospheric plasma component composition and particle densities in air

    Science.gov (United States)

    Kirsanov, Gennady; Chirtsov, Alexander; Kudryavtsev, Anatoliy

    2015-11-01

    Recently discharges in air at atmospheric pressure were the subject of numerous studies. Of particular interest are the cold streams of air plasma, which contains large amounts of chemically active species. It is their action can be decisive in the interaction with living tissues. Therefore, in addition to its physical properties, it is important to know the component composition and particle densities. The goal was to develop a numerical model of atmospheric pressure glow microdischarge in air with the definition of the component composition of plasma. To achieve this goal the task was divided into two sub-tasks, in the first simulated microdischarge atmospheric pressure in air using a simplified set of plasma chemical reactions in order to obtain the basic characteristics of the discharge, which are the initial approximations in the problem of the calculation of the densities with detailed plasma chemistry, including 53 spices and over 600 chemical reactions. As a result of the model was created, which can be adapted for calculating the component composition of plasma of various sources. Calculate the density of particles in the glow microdischarges and dynamics of their change in time.

  18. A Study of Atmospheric Particles Removal in a Low Visibility Outdoor Single Image

    Directory of Open Access Journals (Sweden)

    Muhamad Lazim Bin Talib

    2016-12-01

    Full Text Available Maximum limit of human visibility without the assistance of equipment is 1000 m based on International Commission on Illumination. The use of camera in the outdoor for the purpose of navigation, monitoring, remote sensing and robotic movement sometimes may yield images that are interrupted by haze, fog, smoke, steam and water drops. Fog is the random movement of water drops in the air that normally exists in the early morning. This disorder causes a differential image observed experiences low contrast, obscure, and difficult to identify targets. Analysis of the interference image can restore damaged image as a result of obstacles from atmospheric particles or drops of water during image observation. Generally, images with atmospheric particles contain a homogeneous texture like brightness and a heterogeneous texture which is the object that exists in the atmosphere. Pre-processing method based on the dark channel prior statistical measure of contrast vision and prior knowledge, still produces good image quality but less effective to overcome Halo problem or ring light, and strong lighting. This study aims to propel the development of machine vision industry aimed at navigation or monitoring for ground transportation, air or sea.

  19. Determination of iodine and bromine in coal and atmospheric particles by inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    Sun, Mingxing; Gao, Yunchuan; Wei, Biwen; Wu, Xiaowei

    2010-04-15

    Bromine and iodine in atmospheric particles or coal can cause environmental problems such as destruction of ozone in the atmosphere; therefore, the presence of these compounds has recently received increased attention. Here, a rapid and reliable method for the simultaneous determination of total bromine and iodine using ICP-MS analysis is described. Samples were dissolved in mixtures of 5 mL of HNO(3) and 2 mL of H(2)O(2) in a high pressure microwave digester. The solution was then oxidized by per-sulfate (Na(2)S(2)O(8)) in addition to a small amount of silver nitrate, after which the total bromine and iodine were measured simultaneously by ICP-MS. The signal memory effects of bromine and iodine during analysis were effectively decreased by washing with a new mixture agent (2% alcohol acidic solution, pH 1-2 adjusted with HCl). The detection limits for bromine and iodine using this method were about 3.2 microg L(-1) and 1.1 microg L(-1), respectively. Additionally, the spike recoveries were between 78.7% and 121% for bromine and iodine analysis, while the relative standard deviations ranged from 4.3% to 9.7%, and from 1.5% to 3.4% for bromine and iodine, respectively. The results of this study indicate that the method described here is suitable for the analysis of micro-amounts of bromine and iodine in atmospheric particles and coal samples.

  20. Monitoring of airborne biological particles in outdoor atmosphere. Part 1: Importance, variability and ratios.

    Science.gov (United States)

    Núñez, Andrés; Amo de Paz, Guillermo; Rastrojo, Alberto; García, Ana M; Alcamí, Antonio; Gutiérrez-Bustillo, A Montserrat; Moreno, Diego A

    2016-03-01

    The first part of this review ("Monitoring of airborne biological particles in outdoor atmosphere. Part 1: Importance, variability and ratios") describes the current knowledge on the major biological particles present in the air regarding their global distribution, concentrations, ratios and influence of meteorological factors in an attempt to provide a framework for monitoring their biodiversity and variability in such a singular environment as the atmosphere. Viruses, bacteria, fungi, pollen and fragments thereof are the most abundant microscopic biological particles in the air outdoors. Some of them can cause allergy and severe diseases in humans, other animals and plants, with the subsequent economic impact. Despite the harsh conditions, they can be found from land and sea surfaces to beyond the troposphere and have been proposed to play a role also in weather conditions and climate change by acting as nucleation particles and inducing water vapour condensation. In regards to their global distribution, marine environments act mostly as a source for bacteria while continents additionally provide fungal and pollen elements. Within terrestrial environments, their abundances and diversity seem to be influenced by the land-use type (rural, urban, coastal) and their particularities. Temporal variability has been observed for all these organisms, mostly triggered by global changes in temperature, relative humidity, et cetera. Local fluctuations in meteorological factors may also result in pronounced changes in the airbiota. Although biological particles can be transported several hundreds of meters from the original source, and even intercontinentally, the time and final distance travelled are strongly influenced by factors such as wind speed and direction. [Int Microbiol 2016; 19(1):1-1 3].

  1. Atmospheric number size distributions of soot particles and estimation of emission factors

    Directory of Open Access Journals (Sweden)

    D. Rose

    2006-01-01

    Full Text Available Number fractions of externally mixed particles of four different sizes (30, 50, 80, and 150 nm in diameter were measured using a Volatility Tandem DMA. The system was operated in a street canyon (Eisenbahnstrasse, EI and at an urban background site (Institute for Tropospheric Research, IfT, both in the city of Leipzig, Germany as well as at a rural site (Melpitz (ME, a village near Leipzig. Intensive campaigns of 3–5 weeks each took place in summer 2003 as well as in winter 2003/04. The data set thus obtained provides mean number fractions of externally mixed soot particles of atmospheric aerosols in differently polluted areas and different seasons (e.g. at 80 nm on working days, 60% (EI, 22% (IfT, and 6% (ME in summer and 26% (IfT, and 13% (ME in winter. Furthermore, a new method is used to calculate the size distribution of these externally mixed soot particles from parallel number size distribution measurements. A decrease of the externally mixed soot fraction with decreasing urbanity and a diurnal variation linked to the daily traffic changes demonstrate, that the traffic emissions have a significant impact on the soot fraction in urban areas. This influence becomes less in rural areas, due to atmospheric mixing and transformation processes. For estimating the source strength of soot particles emitted by vehicles (veh, soot particle emission factors were calculated using the Operational Street Pollution Model (OSPM. The emission factor for an average vehicle was found to be (1.5±0.4·1014 #(km·veh. The separation of the emission factor into passenger cars ((5.8±2·1013} #(km·veh and trucks ((2.5±0.9·1015 #(km·veh yielded in a 40-times higher emission factor for trucks compared to passenger cars.

  2. Numerical study of the auroral particle transport in the polar upper atmosphere

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Starting from the Boltzmann equation and with some reasonable assumptions, a one-dimensional transport equation of charged energetic particles is derived by taking account of major interactions with neutral species in the upper atmosphere, including the processes of elastic scattering, the excitation, the ionization and the secondary electron production. The transport equation is numerically solved, for a simplified atmosphere consisting only of nitrogen molecules (N2), to obtain the variations of incident electron fluxes as a function of altitude, energy and pitch angle. The model results can describe fairly the transport characteristics of pre-cipitating auroral electron spectra in the polar upper atmosphere; meanwhile the N2 ionization rates calculated from the modeled differential flux spectra also exhibit good agreements with existing empirical models in terms of several key parameters. Taking the energy flux spectra of precipitating electrons observed by FAST satellite flying over EISCAT site on May 15, 1997 as model inputs, the model-calculated ionization rate profile of neutral atmosphere consists reasonably with that recon-structed from electron density measurements by the radar.

  3. Lung cancer mortality and exposure to atmospheric aerosol particles in Guangzhou, China

    Science.gov (United States)

    Tie, Xuexi; Wu, Dui; Brasseur, Guy

    In recent years, China and other emerging countries have been experiencing severe air pollution problems with high concentrations of atmospheric aerosol particles. Satellite measurements indicate that the aerosol loading of the atmosphere in highly populated regions of China is about 10 times higher than, for example, in Europe and in the Eastern United States. The exposure to extremely high aerosol concentrations might lead to important human health effects, including respiratory and cardiovascular diseases as well as lung cancers. Here, we analyze 52-year historical surface measurements of haze data in the Chinese city of Guangzhou, and show that the dramatic increase in the occurrence of air pollution events between 1954 and 2006 has been followed by a large enhancement in the incidence of lung cancer.

  4. The variation of characteristics of individual particles during the haze evolution in the urban Shanghai atmosphere

    Science.gov (United States)

    Hu, Qingqing; Fu, Hongbo; Wang, Zhenzhen; Kong, Lingdong; Chen, Mindong; Chen, Jianmin

    2016-11-01

    The severe long-lasting haze episode in December 2013 provided a unique opportunity to track the variation of aerosol particles in Shanghai, China. Concentrations and sources of the pollutants varied greatly in severe haze-fog episode (P1), moderate haze episode (P2), and clear episode (P3). Both low wind speed and high relative humidity (RH) during P1 resulted in the high level pollutants of PM2.5 (240.3 ± 167.9 μg m- 3), SO2 (37.9 ± 20.7 μg m- 3), NO2 (111.5 ± 50.2 μg m- 3) and total water-soluble ions (58.73 ± 28.87 μg m- 3), indicating a strong accumulation of local pollutants and secondary species formation. During P2, air masses from the north decreased the concentration level of particles (116.1 ± 65.5 μg m- 3) and increased the visibility, resulting in a moderate degree of pollution. Most of the pollutants dropped to the lowest concentration levels due to the rainfall in P3, and the haze episode ended at 13 December. Single particle analysis showed that C-rich particles exhibited the highest number percentages (30%) in the samples of P1, S/N-rich species (35%) dominated the particles in the samples of P2, and Al/Si-rich particles (23%) were most abundant in the samples of P3. The TEM-EDS analysis confirmed that particles contained more internally mixed components during P1 and P2 than those during P3, suggesting that the particles during P1 and P2 underwent more intense aging in the atmosphere. The single particle analysis indicated that trace metals may promote the heterogeneous transformation of SO2 and NO2 on the surface of the particles during P1, which was in agreement with the highest sulfur oxidation ratio (SOR) and nitrogen oxidation ratio (NOR) observed in the haze-fog episode. Such information will deepen our understanding on the evolution of haze and fog pollutions in China, which will help the government to establish efficient control strategy for air pollution prevention.

  5. PD-FiTE - an efficient method for calculating gas / liquid equilibria in atmospheric aerosol particles

    Science.gov (United States)

    Topping, D.; Lowe, D.; McFiggans, G.; Barley, M.

    2009-04-01

    Assessing the impact of atmospheric aerosol particles on the environment requires adequate representation of appropriate key processes within large scale models. In the absence of primary particulate material, interactions between the atmospheric gaseous components and particles means that the chemical nature of the particles is largely determined by the availability of condensable gaseous material, such as sulphuric and nitric acids, and by the ambient environmental conditions. Gas to particle mass transfer of semi-volatile components,driven by a difference in equilibrium and actual partial pressures above an aerosol particle, is an important factor in determining the evolving chemical composition of the particle and is necessary for predicting aerosol loading and composition. The design of an appropriate framework required for parameterizations of key variables is challenging. These thermodynamic frameworks are often numerically very complex, resulting in significant computational expense. Three dimensional chemical and aerosol transport models demand that computational expense be kept at a minimum,resulting in a trade-off between accuracy and efficiency. To calculate the equilibrium vapour pressure above a solution requires treatment of solution nonideality. This is manifest through activity coefficients of components pertinent to each condensing specie. However, activity coefficients are complex functions of the solution composition. Parameterisation of activity coefficients provides the main focus of this work largely because reducing the numerical complexity whilst retaining a good level of accuracy is very challenging. The approach presented here, the hybrid Partial Derivative Fitted Taylor Expansion (PDFiTE) (Topping et al 2008), builds on previously reported work, with an aim to derive parameters for an accurate and computationally efficient framework through coupling with a complex thermodynamic model. Such a reduction in complexity is important as it is

  6. The link between atmospheric radicals and newly formed particles at a spruce forest site in Germany

    Directory of Open Access Journals (Sweden)

    B. Bonn

    2013-10-01

    Full Text Available It has been claimed for more than a century that atmospheric new particle formation is primarily influenced by the presence of sulphuric acid. However, the activation process of sulphuric acid related clusters into detectable particles is still an unresolved topic. In this study we focus on the PARADE campaign measurements conducted during August/September 2011 at Mt. Kleiner Feldberg in central Germany. During this campaign a set of radicals, organic and inorganic compounds and oxidants and aerosol properties were measured or calculated. We compared a range of organic and inorganic nucleation theories, evaluating their ability to simulate measured particle formation rates at 3 nm in diameter (J3 for a variety of different conditions. Nucleation mechanisms involving only sulphuric acid tentatively captured the observed noon-time daily maximum in J3, but displayed an increasing difference to J3 measurements during the rest of the diurnal cycle. Including large organic radicals, i.e. organic peroxy radicals (RO2 deriving from monoterpenes and their oxidation products in the nucleation mechanism improved the correlation between observed and simulated J3. This supports a recently proposed empirical relationship for new particle formation that has been used in global models. However, the best match between theory and measurements for the site of interest was found for an activation process based on large organic peroxy radicals and stabilized Criegee intermediates (sCI. This novel laboratory derived algorithm simulated the daily pattern and intensity of J3 observed in the ambient data. In this algorithm organic derived radicals are involved in activation and growth and link the formation rate of smallest aerosol particles with OH during daytime and NO3 during nighttime. Because of the RO2s lifetime is controlled by HO2 and NO we conclude that peroxy radicals and NO seem to play an important role for ambient radical chemistry not only with respect to

  7. Molecular understanding of atmospheric particle formation from sulfuric acid and large oxidized organic molecules

    CERN Document Server

    Schobesberger, Siegfried; Bianchi, Federico; Lönn, Gustaf; Ehn, Mikael; Lehtipalo, Katrianne; Dommen, Josef; Ehrhart, Sebastian; Ortega, Ismael K; Franchin, Alessandro; Nieminen, Tuomo; Riccobono, Francesco; Hutterli, Manuel; Duplissy, Jonathan; Almeida, João; Amorim, Antonio; Breitenlechner, Martin; Downard, Andrew J; Dunne, Eimear M; Flagan, Richard C; Kajos, Maija; Keskinen, Helmi; Kirkby, Jasper; Kupc, Agnieszka; Kürten, Andreas; Kurtén, Theo; Laaksonen, Ari; Mathot, Serge; Onnela, Antti; Praplan, Arnaud P; Rondo, Linda; Santos, Filipe D; Schallhart, Simon; Schnitzhofer, Ralf; Sipilä, Mikko; Tomé, António; Tsagkogeorgas, Georgios; Vehkamäki, Hanna; Wimmer, Daniela; Baltensperger, Urs; Carslaw, Kenneth S; Curtius, Joachim; Hansel, Armin; Petäjä, Tuukka; Kulmala, Markku; Donahue, Neil M; Worsnop, Douglas R

    2013-01-01

    Atmospheric aerosols formed by nucleation of vapors affect radiative forcing and therefore climate. However, the underlying mechanisms of nucleation remain unclear, particularly the involvement of organic compounds. Here, we present high-resolution mass spectra of ion clusters observed during new particle formation experiments performed at the Cosmics Leaving Outdoor Droplets chamber at the European Organization for Nuclear Research. The experiments involved sulfuric acid vapor and different stabilizing species, including ammonia and dimethylamine, as well as oxidation products of pinanediol, a surrogate for organic vapors formed from monoterpenes. A striking resemblance is revealed between the mass spectra from the chamber experiments with oxidized organics and ambient data obtained during new particle formation events at the Hyytiälä boreal forest research station. We observe that large oxidized organic compounds, arising from the oxidation of monoterpenes, cluster directly with single sulfuric acid molec...

  8. Quantitative energy-dispersive electron probe X-ray microanalysis for single-particle analysis and its application for characterizing atmospheric aerosol particles

    Indian Academy of Sciences (India)

    Shila Maskey; Chul-Un Ro

    2011-02-01

    An energy-dispersive electron probe X-ray microanalysis (ED-EPMA) technique using an energy-dispersive X-ray detector with an ultra-thin window, designated as low-Z particle EPMA, has been developed. The low-Z particle EPMA allows the quantitative determination of concentrations of low-Z elements such as C, N and O, as well as higher-Z elements that can be analysed by conventional ED-EPMA. The quantitative determination of low-Z elements (using full Monte Carlo simulations, from the electron impact to the X-ray detection) in individual particles has improved the applicability of single-particle analysis, especially in atmospheric environmental aerosol research; many environmentally important atmospheric particles, e.g. sulphates, nitrates, ammonium and carbonaceous particles, contain low-Z elements. To demonstrate its practical applicability, the application of the low-Z particle EPMA for the characterization of Asian Dust, urban and subway aerosol particles is shown herein. In addition, it is demonstrated that the Monte Carlo calculation can also be applied in a quantitative single-particle analysis using transmission electron microscopy (TEM) coupled with energy-dispersive X-ray spectrometry (EDX), showing that the technique is useful and reliable for the characterization of submicron aerosol particles

  9. Growth of atmospheric nano-particles by heterogeneous nucleation of organic vapor

    Directory of Open Access Journals (Sweden)

    J. Wang

    2013-07-01

    Full Text Available Atmospheric aerosols play critical roles in air quality, public health, and visibility. In addition, they strongly influence climate by scattering solar radiation and by changing the reflectivity and lifetime of clouds. One major but still poorly understood source of atmospheric aerosols is new particle formation, which consists of the formation of thermodynamically stable clusters from trace gas molecules (homogeneous nucleation followed by growth of these clusters to a detectable size (~3 nm. Because freshly nucleated clusters are most susceptible to loss due to high rate of coagulation with pre-existing aerosol population, the initial growth rate strongly influences the rate of new particle formation and ambient aerosol population. Whereas many field observations and modeling studies indicate that organics enhance the initial growth of the clusters and therefore new particle formation, thermodynamic considerations would suggest that the strong increase of equilibrium vapor concentration due to cluster surface curvature (Kelvin effect may prevent ambient organics from condensing on these small clusters. Here, the contribution of organics to the initial cluster growth is described as heterogeneous nucleation of organic molecules onto these clusters. We find that the strong gradient in cluster population with respect to its size leads to positive cluster number flux. This positive flux drives the growth of clusters substantially smaller than the Kelvin diameter, conventionally considered the minimum particle size that can be grown through condensation. The conventional approach neglects the contribution from the cluster concentration gradient, and underestimates the cluster survival probabilities by a factor of up to 60 if early growth of clusters is due to both condensation of sulfuric acid and heterogeneous nucleation of organic vapors.

  10. Growth of atmospheric nano-particles by heterogeneous nucleation of organic vapor

    Science.gov (United States)

    Wang, J.; McGraw, R. L.; Kuang, C.

    2013-07-01

    Atmospheric aerosols play critical roles in air quality, public health, and visibility. In addition, they strongly influence climate by scattering solar radiation and by changing the reflectivity and lifetime of clouds. One major but still poorly understood source of atmospheric aerosols is new particle formation, which consists of the formation of thermodynamically stable clusters from trace gas molecules (homogeneous nucleation) followed by growth of these clusters to a detectable size (~3 nm). Because freshly nucleated clusters are most susceptible to loss due to high rate of coagulation with pre-existing aerosol population, the initial growth rate strongly influences the rate of new particle formation and ambient aerosol population. Whereas many field observations and modeling studies indicate that organics enhance the initial growth of the clusters and therefore new particle formation, thermodynamic considerations would suggest that the strong increase of equilibrium vapor concentration due to cluster surface curvature (Kelvin effect) may prevent ambient organics from condensing on these small clusters. Here, the contribution of organics to the initial cluster growth is described as heterogeneous nucleation of organic molecules onto these clusters. We find that the strong gradient in cluster population with respect to its size leads to positive cluster number flux. This positive flux drives the growth of clusters substantially smaller than the Kelvin diameter, conventionally considered the minimum particle size that can be grown through condensation. The conventional approach neglects the contribution from the cluster concentration gradient, and underestimates the cluster survival probabilities by a factor of up to 60 if early growth of clusters is due to both condensation of sulfuric acid and heterogeneous nucleation of organic vapors.

  11. Modeling the possible role of iodine oxides in atmospheric new particle formation

    Directory of Open Access Journals (Sweden)

    S. Pechtl

    2006-01-01

    Full Text Available We studied the possible role of iodine oxides in atmospheric new particle formation with the one-dimensional marine boundary layer model MISTRA, which includes chemistry in the gas and aerosol phase as well as aerosol microphysics. The chemical reaction set focuses on halogen (Cl-Br-I chemistry. We included a two-step nucleation parameterization, where in the first step, the 'real' nucleation process is parameterized, i.e., the formation of cluster-sized nuclei via homogeneous condensation of gases. We considered both ternary sulfuric acid-ammonia-water nucleation and homomolecular homogeneous OIO nucleation. For the latter, we derived a parameterization based on combined laboratory-model studies. The second step of the nucleation parameterization treats the 'apparent' nucleation rate, i.e., the growth of clusters into the model's lowest size bin by condensable vapors such as OIO. We compared different scenarios for a clean marine versus a polluted continental background atmosphere. In every scenario, we assumed the air to move, independent of its origin, first over a coastal region (where it is exposed to surface fluxes of different reactive iodine precursors and later over the open ocean. According to these sensitivity studies, in the clean marine background atmosphere OIO can be responsible for both homogeneous nuclei formation and the subsequent growth of the clusters to detectable sizes. In contrast to this, in the continental case with its higher levels of pollutants, gas phase OIO mixing ratios, and hence related nucleation rates, are significantly lower. Compared to ternary H2SO4-NH3-H2O nucleation, homogeneous OIO nucleation can be neglected for new particle formation in this case, but OIO can contribute to early particle growth, i.e., to apparent nucleation rates. In general, we found OIO to be more important for the growth of newly formed particles than for the formation of new nuclei. According to our studies, observations of

  12. Characterisation of iron-rich atmospheric submicrometre particles in the roadside environment

    Science.gov (United States)

    Sanderson, P.; Su, S. S.; Chang, I. T. H.; Delgado Saborit, J. M.; Kepaptsoglou, D. M.; Weber, R. J. M.; Harrison, Roy M.

    2016-09-01

    Human exposure to ambient metallic nanoparticles is an area of great interest owing to their potential health impacts. Ambient metallic nanoparticles found in the roadside environment are contributed by combustion engines and wear of brakes, tyres and road surfaces. Submicrometre atmospheric particles collected at two UK urban sites have been subject to detailed characterisation. It is found that many metallic nanoparticles collected from roadside sampling sites are rich in iron. The Fe-rich nanoparticles can be classified into (1) high Fe content (ca 90 wt%) with each alloying element less than 1 wt%; and (2) moderate Fe content (<75 wt%) with high manganese and silicon content. Both clusters contain a variable mix of minor constituents, Mn, S and Si being most important in the high-Fe group. The moderate Fe group also contains Zn, Cu, Ba, Al and Ca. The Fe-rich nanoparticles exhibit primary particle sizes ranging between 20 and 30 nm, although some much larger particles up to around 100 nm can also be observed, along with some very small particles of 10 nm or less. These tend to agglomerate forming clusters ranging from ∼200 nm to 1 μm in diameter. The iron-rich particles observed are oxides, taking the form of spheres or multifaceted regular polyhedra. Analysis by EELS shows that both high- and moderate-Fe groups include particles of FeO, Fe3O4, α-Fe2O3 and γ-Fe2O3 of which γ-Fe2O3 is the most prominent. Internal mixing of different Fe-oxides is not observed.

  13. Treatment of airborne asbestos and asbestos-like microfiber particles using atmospheric microwave air plasma.

    Science.gov (United States)

    Averroes, A; Sekiguchi, H; Sakamoto, K

    2011-11-15

    Atmospheric microwave air plasma was used to treat asbestos-like microfiber particles that had two types of ceramic fiber and one type of stainless fiber. The treated particles were characterized via scanning electron microscopy (SEM) and X-ray diffraction (XRD). The experiment results showed that one type of ceramic fiber (Alumina:Silica=1:1) and the stainless fiber were spheroidized, but the other type of ceramic fiber (Alumina:Silica=7:3) was not. The conversion of the fibers was investigated by calculating the equivalent diameter, the aspect ratio, and the fiber content ratio. The fiber content ratio in various conditions showed values near zero. The relationship between the normalized fiber vanishing rate and the energy needed to melt the particles completely per unit surface area of projected particles, which is defined as η, was examined and seen to indicate that the normalized fiber vanishing rate decreased rapidly with the increase in η. Finally, some preliminary experiments for pure asbestos were conducted, and the analysis via XRD and phase-contrast microscopy (PCM) showed the availability of the plasma treatment.

  14. Chemical characteristics and source of size-fractionated atmospheric particle in haze episode in Beijing

    Science.gov (United States)

    Tan, Jihua; Duan, Jingchun; Zhen, Naijia; He, Kebin; Hao, Jiming

    2016-01-01

    The abundance, behavior, and source of chemical species in size-fractionated atmospheric particle were studied with a 13-stage low pressure impactor (ELPI) during high polluted winter episode in Beijing. Thirty three elements (Al, Ca, Fe, K, Mg, Na, Si, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Sr, Zr, Mo, Ag, Cd, In, Sn, Sb, Cs, Ba, Hg, Tl, and Pb) and eight water soluble ions (Cl-, NO3-, SO42 -, NH4+, Na+, K+, Ca2 +, and Mg2 +) were determined by ICP/MS and IC, respectively. The size distribution of TC (OC + EC) was reconstructed. Averagely, 51.5 ± 5.3% and 74.1 ± 3.7% of the total aerosol mass was distributed in the sub-micron (PM1) and fine particle (PM2.5), respectively. A significant shift to larger fractions during heavy pollution episode was observed for aerosol mass, NH4+, SO42 -, NO3-, K, Fe, Cu, Zn, Cd, and Pb. The mass size distributions of NH4+, SO42 -, NO3-, and K were dominated by accumulation mode. Size distributions of elements were classified into four main types: (I) elements were enriched within the accumulation mode (water soluble ions. Dust, vehicle, aged coal combustion, and sea salt were identified, and the size resolved source apportionments were discussed. Aged coal combustion was the important source of fine particles and dust contributed most to coarse particle.

  15. Spectro-microscopic Characterization of Physical Properties and Phase Separations in Individual Atmospheric Particles

    Science.gov (United States)

    OBrien, R. E.; Wang, B.; Neu, A.; Kelly, S. T.; Lundt, N.; Epstein, S. A.; MacMillan, A.; You, Y.; Laskin, A.; Nizkorodov, S.; Bertram, A. K.; Moffet, R.; Gilles, M.

    2013-12-01

    The phase state and liquid-liquid phase separations of ambient and laboratory generated aerosol particles were investigated using (1) scanning transmission x-ray microscopy/near-edge x-ray absorption fine structure spectroscopy (STXM/NEXAFS) coupled to a relative humidity (RH) controlled in-situ chamber and (2) environmental scanning electron microscopy (ESEM). The phase states of the particles were determined from measurements of their size and optical density. A comparison is made between the observed phase states of ambient samples and of laboratory generated aerosols to determine how well laboratory samples represent the phase of ambient samples. In addition, liquid-liquid phase separations in laboratory generated particles were investigated. Preliminary results showing that liquid-liquid phase separations occur at RH's between the deliquescence and efflorescence points and that the organic phase surrounds the inorganic phase will be presented. The STXM/NEXAFS technique provides insight into the degree of mixing at the deliquescence point and the degree of phase separation for particles of atmospherically relevant sizes.

  16. Study on the preparation and properties of ultrafine copper powder

    Institute of Scientific and Technical Information of China (English)

    LIU; Wei-ping; HUANG; Lin; YIN; Yan-hong

    2005-01-01

    In the study, the common copper powder is used as sample, the ultrafine copper powder is researched by a new process of high energy ball milling. The influence of the milling time, the milling intensity, the milling medium, the ratio of hall to material, the dry milling and the wet milling on copper powder size are studied and the rule of every factors influencing properties of copper particle size and specific surface area under the best experimental conditions are acquired. By the regressive analysis of experimental results under the best conditions, the characteristic equation of copper particle prepared by high energy milling is confirmed.

  17. New Ion-Nucleation Mechanism Relevant for the Earth's Atmosphere

    DEFF Research Database (Denmark)

    Marsh, N.D.; Svensmark, Henrik; Pedersen, Jens Olaf Pepke

    stages of particle coagulation and condensation have been performed and compared with the experimental results. The simulations indicate that a stable distribution of sub 3nm particles exists that cannot be detected using standard techniques for measuring atmospheric aerosol, and that the nucleation rate......Experimental studies of ultra-fine aerosol nucleation in clean atmospheric air, containing trace amounts of ozone, sulphur dioxide, and water vapour suggest that the production rate of critical clusters is sensitive to ionisation. To assess this sensitivity numerical simulations of the initial...... particles with the potential to influence the transparency of Earth's atmosphere. This is consistent with a number of recent studies indicating that variations in the density of cosmic rays arriving at Earth have affected climate over a wide range of time scales....

  18. Effectiveness of the Top-Down Nanotechnology in the Production of Ultrafine Cement (~220 nm

    Directory of Open Access Journals (Sweden)

    Byung-Wan Jo

    2014-01-01

    Full Text Available The present investigation is dealing with the communition of the cement particle to the ultrafine level (~220 nm utilizing the bead milling process, which is considered as a top-down nanotechnology. During the grinding of the cement particle, the effect of various parameters such as grinding time (1–6 h and grinding agent (methanol and ethanol on the production of the ultrafine cement has also been investigated. Performance of newly produced ultrafine cement is elucidated by the chemical composition, particle size distribution, and SEM and XRD analyses. Based on the particle size distribution of the newly produced ultrafine cement, it was assessed that the size of the cement particle decreases efficiently with increase in grinding time. Additionally, it is optimized that the bead milling process is able to produce 90% of the cement particle <350 nm and 50% of the cement particle < 220 nm, respectively, after 6.3 h milling without affecting the chemical phases. Production of the ultrafine cement utilizing this method will promote the construction industries towards the development of smart and sustainable construction materials.

  19. Formation of Sunquakes in Hydrodynamic Flaring Atmospheres Heated by Mixed Particle Beams

    Science.gov (United States)

    Zharkova, V. V.; Zharkov, S.

    2015-12-01

    We present hydrodynamic simulations of flaring atmospheres of the Sun heated by mixed particle beams and investigate their effects on the solar interior beneath the photosphere for production of acoustic waves, or sunquakes. The temperature, density and macro-velocity variations are calculated as functions of both column and linear depths for different mixed beams revealing strong sweeping of a flaring atmosphere under the quiet photosphere level (QFL). This results in subsequent plasma evaporation into the upper atmosphere and formation of supersonic shocks moving into the solar interior and terminating at depths of 300-5000 km beneath the QFL. The shocks deposited at different depths below the photosphere are found to define the parameters of seismic responses in the interior and their observation as sunquakes, according to the hydrodynamic model of wave propagation (Zharkov, 2013). In addition, we compare temporal and spatial distributions of HXR and optical emission in a few acoustically active flares with those produced by the complex simulations above, in attempt to resolve the puzzle of co-spatial formation of HXR and WL emission reported by Martinez-Oliveros et al. (2012).

  20. The effect of atmospheric aerosol particles and clouds on net ecosystem exchange in the Amazon

    Science.gov (United States)

    Cirino, G. G.; Souza, R. A. F.; Adams, D. K.; Artaxo, P.

    2014-07-01

    Carbon cycling in the Amazon is closely linked to atmospheric processes and climate in the region as a consequence of the strong coupling between the atmosphere and biosphere. This work examines the effects of changes in net radiation due to atmospheric aerosol particles and clouds on the net ecosystem exchange (NEE) of CO2 in the Amazon region. Some of the major environmental factors affecting the photosynthetic activity of plants, such as air temperature and relative humidity, were also examined. An algorithm for clear-sky irradiance was developed and used to determine the relative irradiance, f, which quantifies the percentage of solar radiation absorbed and scattered due to atmospheric aerosol particles and clouds. Aerosol optical depth (AOD) was calculated from irradiances measured with the MODIS (Moderate Resolution Imaging Spectroradiometer) sensor, onboard the Terra and Aqua satellites, and was validated with ground-based AOD measurements from AERONET (Aerosol Robotic Network) sun photometers. Carbon fluxes were measured using eddy covariance technique at the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) flux towers. Two sites were studied: the Jaru Biological Reserve (RBJ), located in Rondonia, and the Cuieiras Biological Reserve at the K34 LBA tower (located in a preserved region in the central Amazon). Analysis was performed continuously from 1999 to 2009 at K34 and from 1999 to 2002 at RBJ, and includes wet, dry and transition seasons. In the Jaru Biological Reserve, a 29% increase in carbon uptake (NEE) was observed when the AOD ranged from 0.10 to 1.5 at 550 nm. In the Cuieiras Biological Reserve, the aerosol effect on NEE was smaller, accounting for an approximate 20% increase in NEE. High aerosol loading (AOD above 3 at 550 nm) or high cloud cover leads to reductions in solar flux and strong decreases in photosynthesis up to the point where NEE approaches zero. The observed increase in NEE is attributed to an enhancement (~50%) in

  1. The effect of atmospheric aerosol particles and clouds on Net Ecosystem Exchange in Amazonia

    Science.gov (United States)

    Cirino, G. G.; Souza, R. F.; Adams, D. K.; Artaxo, P.

    2013-11-01

    Carbon cycling in Amazonia is closely linked to atmospheric processes and climate in the region as a consequence of the strong coupling between the atmosphere and biosphere. This work examines the effects of changes in net radiation due to atmospheric aerosol particles and clouds on the Net Ecosystem Exchange (NEE) of CO2 in the Amazon region. Some of the major environmental factors affecting the photosynthetic activity of plants, such as air temperature and relative humidity were also examined. An algorithm for clear-sky irradiance was developed and used to determine the relative irradiance f, which quantifies the percentage of solar radiation absorbed and scattered due to atmospheric aerosol particles and clouds. Aerosol optical depth (AOD) was calculated from irradiances measured with the MODIS (Moderate Resolution Imaging Spectroradiometer) sensor, onboard the TERRA and AQUA satellites, and was validated with ground-based AOD measurements from AERONET sun photometers. Carbon fluxes were measured using eddy-correlation techniques at LBA (The Large Scale Biosphere-Atmosphere Experiment in Amazonia) flux towers. Two sites were studied: the Biological Reserve of Jaru (located in Rondonia) and the Cuieiras Biological Reserve (located in a preserved region in central Amazonia). In the Jaru Biological Reserve, a 29% increase in carbon uptake (NEE) was observed when the AOD ranged from 0.10 to 1.5. In the Cuieiras Biological Reserve, this effect was smaller, accounting for an approximately 20% increase in NEE. High aerosol loading (AOD above 3 at 550 nm) or cloud cover leads to reductions in solar flux and strong decreases in photosynthesis up to the point where NEE approaches 0. The observed increase in NEE is attributed to an enhancement (~50%) in the diffuse fraction of photosynthetic active radiation (PAR). Significant changes in air temperature and relative humidity resulting from changes in solar radiation fluxes under high aerosol loading were also observed at

  2. Photochemistry of iron(III)-carboxylato complexes in aqueous atmospheric particles

    Science.gov (United States)

    Weller, Christian; Herrmann, Hartmut

    2010-05-01

    Iron is always present in the atmosphere in concentrations from ~10-9 M (clouds, rain) up to ~10-3 M (fog, particles). Sources are mainly mineral dust emissions. Iron complexes are very good absorbers in the UV-VIS actinic region and therefore photo-chemically reactive. Iron complex photolysis leads to radical production and can initiate radical chain reactions, which is related to the oxidizing capacity of the atmosphere. These radical chain reactions are involved in the decomposition and transformation of a variety of chemical compounds in cloud droplets and deliquescent particles. Additionally, the photochemical reaction itself can be a degradation pathway for organic compounds with the ability to bind iron. Iron-complexes of atmospherically relevant coordination compounds like oxalate, malonate, succinate, glutarate, tartronate, gluconate, pyruvate and glyoxalate have been investigated in laboratory experiments. Iron speciation depends on the iron-ligand ratio and the pH. The most suitable experimental conditions were calculated with a speciation program (Visual Minteq). The solutions were prepared accordingly and transferred to a 1 cm quartz cuvette and flash-photolyzed with an excimer laser at wavelengths 308 or 351 nm. Photochemically produced Fe2+ has been measured by spectrometry at 510 nm as Fe(phenantroline)32+. Fe2+ overall effective quantum yields have been calculated with the concentration of photochemically produced Fe2+ and the measured energy of the excimer laser pulse. The laser pulse energy was measured with a pyroelectric sensor. For some iron-carboxylate systems the experimental parameters like the oxygen content of the solution, the initial iron concentration and the incident laser energy were systematically altered to observe an effect on the overall quantum yield. The dependence of some quantum yields on these parameters allows in some cases an interpretation of the underlying photochemical reaction mechanism. Quantum yields of malonate

  3. 放电等离子烧结合成TiC/TiB2颗粒增强的超细晶钛基复合材料%Ultrafine-grained Ti-based composites reinforced by TiC/TiB2 particles fabricated by spark plasma sintering

    Institute of Scientific and Technical Information of China (English)

    陈友; 梁甲宏; 杨超; 李元元

    2011-01-01

    Ultrafine-grained Ti-based composites reinforced by TiC/TiB2 particles with different volume fractions were fabricated by spark plasma sintering (SPS) and crystallization of amorphous phase. The fabricated ultrafine-grained composites were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM) and universal materials tester. Results show that the relative densities of the samples decrease with the increase of the TiC/TiB2 addition. No reactions are observed to occur between the matrix and the TiC particles; the addition of TiB2 particles greatly changes the interface between the TiB2 particles and the matrix, but has little influence on the matrix, which is composed of continuously distributed β-Ti(Nb) phase and (Cu, Ni)-Ti2 phase. Moreover, the Ti-based composites with TiC particles have higher fracture strength than those with TiB2 particles. The sample with 35 vol.% TiC particles has the highest fracture strength of 2209 Mpa.%采用放电等离子烧结技术结合非晶晶化法制备了不同体积分数的TiC/TiB2颗粒增强的超细晶钛基复合材料.运用X射线衍射分析、扫描电子显微镜和万能材料试验机等实验手段,对合成的超细晶钛基复合材料进行测试分析.结果表明:随着外加TiC/TiB2颗粒的增加,钛基复合材料试样的致密度逐渐降低.TiC颗粒与基体不发生反应,而TiB2颗粒的加入改变了TiB2颗粒与基体界面的组织形貌,但对远离界面处的基体组织形貌没有影响,其组织均由-Ti(Nb)相和(Cu,Ni)-Ti2相组成,且ββ-Ti(Nb)相连续分布.同时,TiC颗粒的增强效果优于TiB2颗粒,35 vol.%(体积分数)TiC颗粒增强的复合材料试样的断裂强度最高,达2209 MPa.

  4. Particle-Induced X-Ray Emission Analysis of Atmospheric Aerosols

    Science.gov (United States)

    Gleason, Colin; Harrington, Charles; Schuff, Katie; Battaglia, Maria; Moore, Robert; Turley, Colin; Vineyard, Michael; Labrake, Scott

    2010-11-01

    We are developing a research program in ion-beam analysis (IBA) of atmospheric aerosols at the Union College Ion-Beam Analysis Laboratory to study the transport, transformation, and effects of airborne pollution in Upstate New York. The simultaneous applications of the IBA techniques of particle-induced X-ray emission (PIXE), Rutherford back-scattering spectrometry (RBS), particle-induced gamma-ray emission (PIGE), and proton elastic scattering analysis (PESA) is a powerful tool for the study of airborne pollution because they are non-destructive and provide quantitative information on nearly all elements of the periodic table. PIXE is the main IBA technique because it is able to detect nearly all elements from Na to U with high sensitivities and low detection limits. The aerosol samples are collected with cascade impactors that allow for the study of particulate matter as a function of particle size and the samples are analyzed using proton beams with energies around 2 MeV from the Union College 1.1-MV Pelletron Accelerator. The emitted X-rays are measured using a silicon drift detector with a resolution of 136 eV. We will describe how the aerosol samples were collected, discuss the PIXE analysis, and present preliminary results.

  5. Factors influencing the crystallization and the densification of ultrafine Si/N/C powders

    Energy Technology Data Exchange (ETDEWEB)

    Lences, Z. [Slovenska Akademia Vied, Bratislava (Slovakia). Inst. of Inorganic Chemistry; Bellosi, A. [CNR IRTEC, Research Institute for Ceramics Technology, Via Granarolo 64, 48018 Faenza (Italy); Monteverde, F. [CNR IRTEC, Research Institute for Ceramics Technology, Via Granarolo 64, 48018 Faenza (Italy)

    1995-06-01

    The employment of nanocomposite Si/N/C laser-formed powders to produce high performance ceramics results in several technological problems related to their nanometer particle size and to their high affinity for oxygen, which influence phase composition and densification. This study has focused on several aspects: the improvement of experimental methodologies for processing of ultrafine powders in a compact green body and for the addition of sintering aids; the evaluation of the starting composition of the Si/N/C ultrafine amorphous powders and of the thermal treatment conditions (temperature, time, atmosphere) on phase composition, thermal stability, grain size, specific surface area and crystallite size; and the production and characterization of dense Si{sub 3}N{sub 4}/SiC composites. Above 1400 C the amorphous Si/N/C powders crystallize in {alpha}- and {beta}-Si{sub 3}N{sub 4}, SiC and Si{sub 2}N{sub 2}O, their relative amounts and grain sizes depending on processing conditions. The phenomena are discussed on the basis of a series of reactions involving the formation of intermediates in the system Si-C-N-O. After densification by hot pressing, a very fine microstructure ({approx}100 nm) was observed in the dense Si{sub 3}N{sub 4}/SiC composites. High values of hardness (H{sub V}{>=}21 GPa) and good values of fracture toughness (K{sub IC}{approx}4.8 MPa m{sup 1/2}) were measured. ((orig.))

  6. Simulation of ion motion at atmospheric pressure: particle tracing versus electrokinetic flow.

    Science.gov (United States)

    Wissdorf, Walter; Pohler, Larissa; Klee, Sonja; Müller, David; Benter, Thorsten

    2012-02-01

    Results obtained with two computational approaches for the simulation of ion motion at elevated pressure are compared with experimentally derived ion current data. The computational approaches used are charged particle tracings with the software package SIMION ver. 8 and finite element based calculations using the software package Comsol Multiphysics ver. 4.0/4.0a. The experimental setup consisted of a tubular corona discharge ion source coupled to a cylindrical measurement chamber held at atmospheric pressure. Generated ions are flown into the chamber at essentially subsonic laminar isothermal conditions. In the simulations, strictly stationary conditions were assumed. The results show very good agreement between the SIMION/SDS model and experimental data. For the Comsol model, only qualitative agreement is observed.

  7. Influences of fireworks on chemical characteristics of atmospheric fine and coarse particles during Taiwan's Lantern Festival

    Science.gov (United States)

    Tsai, Hsieh-Hung; Chien, Li-Hsing; Yuan, Chung-Shin; Lin, Yuan-Chung; Jen, Yi-Hsiu; Ie, Iau-Ren

    2012-12-01

    In recent years, the celebration activities of various folk-custom festivals have been getting more and more attention from the citizens in Taiwan. Festivities throughout the whole island are traditionally accompanied by loud and brightly colored firework displays. Among these activities, the firework displays during Taiwan's Lantern Festival in Kaohsiung harbor is one of the largest festivals in Taiwan each year. Therefore, it is of importance to investigate the influence of fireworks displays on the ambient air quality during the Taiwan's Lantern Festival. Field measurements of atmospheric particulate matter (PM) were conducted on February 9th-11th, 2009 during Taiwan's Lantern Festival in Kaohsiung City. Moreover, three kinds of fireworks powders obtained from the same manufacturing factory producing Kaohsiung Lantern Festival fireworks were burned in a self-designed combustion chamber to determine the physicochemical properties of the fireworks' particles and to establish the source profile of firework burning. Several metallic elements of PM during the firework display periods were notably higher than those during the non-firework periods. The concentrations of Mg, K, Pb, and Sr in PM2.5 during the firework periods were 10 times higher than those during the non-firework periods. Additionally, the Cl-/Na+ ratio was approximately 3 during the firework display periods as Cl- came from the chlorine content of the firework powder. Moreover, the OC/EC ratio increased up to 2.8. Results obtained from PCA and CMB receptor modeling showed that major sources of atmospheric particles during the firework display periods in Kaohsiung harbor were fireworks, vehicular exhausts, soil dusts and marine sprays. Particularly, on February 10th, the firework displays contributed approximately 25.2% and 16.6% of PM10 at two downwind sampling sites, respectively.

  8. Fragmentation and Growth Energetics of Clusters Relevant to Atmospheric New Particle Formation

    Science.gov (United States)

    Bzdek, B. R.; DePalma, J. W.; Ridge, D. P.; Laskin, J.; Johnston, M. V.

    2013-12-01

    The exact mechanisms by which small clusters form and grow in the atmosphere are poorly understood, but this process may significantly impact cloud condensation nuclei number concentrations and global climate. Sulfuric acid is the key chemical component to new particle formation. However, basic species such as ammonia are also important. Few laboratory experiments address the kinetics or thermodynamics of acid and base incorporation into small clusters. This work utilizes a Fourier transform ion cyclotron resonance mass spectrometer equipped with surface-induced dissociation (FTICR-SID) to investigate time- and collision energy-resolved fragmentation of positively charged ammonium bisulfate clusters. The assumption underlying the experiment is that cluster growth can be considered the reverse of cluster fragmentation. Critical energies for fragmentation are obtained from Rice-Ramsperger-Kassel-Marcus/Quasi-Equilibrium Theory (RRKM/QET) modeling of the experimental data and are compared to quantum chemical calculations of the thermodynamics of cluster fragmentation. Fragmentation of ammonium bisulfate clusters occurs by two pathways: 1) a two-step pathway whereby the cluster sequentially loses ammonia followed by sulfuric acid and 2) a one-step pathway whereby the cluster loses an ammonium bisulfate molecule. Experimental critical energies for loss of an ammonia molecule and loss of an ammonium bisulfate molecule are higher than the thermodynamic values. If cluster growth is considered the reverse of cluster fragmentation, these results suggest that these clusters can grow by first adding sulfuric acid and then adding ammonia. Additionally, these results suggest the presence of an activation barrier to describe the incorporation of ammonia into small acidic clusters and therefore imply that kinetically (i.e. diffusion) limited growth should not be assumed. An important corollary is that models of atmospheric new particle formation should be revised to consider

  9. Association between the concentration of fine particles in the atmosphere and acute respiratory diseases in children

    Directory of Open Access Journals (Sweden)

    Antônio Paula Nascimento

    Full Text Available ABSTRACT OBJECTIVE To analyze the association between fine particulate matter concentration in the atmosphere and hospital care by acute respiratory diseases in children. METHODS Ecological study, carried out in the region of Grande Vitória, Espírito Santo, in the winter (June 21 to September 21, 2013 and summer (December 21, 2013 to March 19, 2014. We assessed data of daily count for outpatient care and hospitalization by respiratory diseases (ICD-10 in children from zero to 12 years in three hospitals in the Region of Grande Vitória. For collecting fine particulate matter, we used portable samplers of particles installed in six locations in the studied region. The Generalized Additive Model with Poisson distribution, fitted for the effects of predictor covariates, was used to evaluate the relationship between respiratory outcomes and concentration of fine particulate matter. RESULTS The increase of 4.2 µg/m3 (interquartile range in the concentration of fine particulate matter increased in 3.8% and 5.6% the risk of medical care or hospitalization, respectively, on the same day and with six-day lag from the exposure. CONCLUSIONS We identified positive association between outpatient care and hospitalizations of children under 12 years due to acute respiratory diseases and the concentration of fine particulate matter in the atmosphere.

  10. The origin of the reactivity of the Criegee intermediate: implications for atmospheric particle growth

    Energy Technology Data Exchange (ETDEWEB)

    Miliordos, Evangelos; Xantheas, Sotiris S.

    2016-01-18

    The electronic structure of the simplest Criegee intermediate (H₂COO) is practically that of a closed shell. On the biradical scale (β) from 0 (pure closed shell) to 1 (pure biradical) it registers a mere β=0.10, suggesting that a Lewis structure of a H₂C=Oδ+-Oδ- zwitterion best describes its ground electronic state. However, this picture of a nearly inert closed shell contradicts its rich atmospheric reactivity. It is the mixing of its ground with the first triplet excited state, which is a pure biradical state of the type H₂C•-O-O•, that is responsible for the formation of strongly bound products during reactions inducing atmospheric particle growth. This work was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. This research also used resources of the National Energy Research Scientific Computing Center, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

  11. Middle atmosphere response to the solar cycle in irradiance and ionizing particle precipitation

    Directory of Open Access Journals (Sweden)

    K. Semeniuk

    2011-05-01

    Full Text Available The impact of NOx and HOx production by three types of energetic particle precipitation (EPP, auroral zone medium and high energy electrons, solar proton events and galactic cosmic rays on the middle atmosphere is examined using a chemistry climate model. This process study uses ensemble simulations forced by transient EPP derived from observations with one-year repeating sea surface temperatures and fixed chemical boundary conditions for cases with and without solar cycle in irradiance. Our model results show a wintertime polar stratosphere ozone reduction of between 3 and 10 % in agreement with previous studies. EPP is found to modulate the radiative solar cycle effect in the middle atmosphere in a significant way, bringing temperature and ozone variations closer to observed patterns. The Southern Hemisphere polar vortex undergoes an intensification from solar minimum to solar maximum instead of a weakening. This changes the solar cycle variation of the Brewer-Dobson circulation, with a weakening during solar maxima compared to solar minima. In response, the tropical tropopause temperature manifests a statistically significant solar cycle variation resulting in about 4 % more water vapour transported into the lower tropical stratosphere during solar maxima compared to solar minima. This has implications for surface temperature variation due to the associated change in radiative forcing.

  12. Isotopic composition for source identification of mercury in atmospheric fine particles

    Science.gov (United States)

    Huang, Qiang; Chen, Jiubin; Huang, Weilin; Fu, Pingqing; Guinot, Benjamin; Feng, Xinbin; Shang, Lihai; Wang, Zhuhong; Wang, Zhongwei; Yuan, Shengliu; Cai, Hongming; Wei, Lianfang; Yu, Ben

    2016-09-01

    The usefulness of mercury (Hg) isotopes for tracing the sources and pathways of Hg (and its vectors) in atmospheric fine particles (PM2.5) is uncertain. Here, we measured Hg isotopic compositions in 30 potential source materials and 23 PM2.5 samples collected in four seasons from the megacity Beijing (China) and combined the seasonal variation in both mass-dependent fractionation (represented by the ratio 202Hg / 198Hg, δ202Hg) and mass-independent fractionation of isotopes with odd and even mass numbers (represented by Δ199Hg and Δ200Hg, respectively) with geochemical parameters and meteorological data to identify the sources of PM2.5-Hg and possible atmospheric particulate Hg transformation. All PM2.5 samples were highly enriched in Hg and other heavy metals and displayed wide ranges of both δ202Hg (-2.18 to 0.51 ‰) and Δ199Hg (-0.53 to 0.57 ‰), as well as small positive Δ200Hg (0.02 to 0.17 ‰). The results indicated that the seasonal variation in Hg isotopic composition (and elemental concentrations) was likely derived from variable contributions from anthropogenic sources, with continuous input due to industrial activities (e.g., smelting, cement production and coal combustion) in all seasons, whereas coal combustion dominated in winter and biomass burning mainly found in autumn. The more positive Δ199Hg of PM2.5-Hg in spring and early summer was likely derived from long-range-transported Hg that had undergone extensive photochemical reduction. The study demonstrated that Hg isotopes may be potentially used for tracing the sources of particulate Hg and its vectors in the atmosphere.

  13. Effect of atmospheric ageing on volatility and ROS of biodiesel exhaust nano-particles

    Directory of Open Access Journals (Sweden)

    A. M. Pourkhesalian

    2015-03-01

    Full Text Available In the prospect of limited energy resources and climate change, effects of alternative biofuels on primary emissions are being extensively studied. Our two recent studies have shown that biodiesel fuel composition has a~significant impact on primary particulate matter emissions. It was also shown that particulate matter caused by biodiesels was substantially different from the emissions due to petroleum diesel. Emissions appeared to have higher oxidative potential with the increase in oxygen content and decrease of carbon chain length and unsaturation levels of fuel molecules. Overall, both studies concluded that chemical composition of biodiesel is more important than its physical properties in controlling exhaust particle emissions. This suggests that the atmospheric ageing processes, including secondary organic aerosol formation, of emissions from different fuels will be different as well. In this study, measurements were conducted on a modern common-rail diesel engine. To get more information on realistic properties of tested biodiesel particulate matter once they are released into the atmosphere, particulate matter was exposed to atmospheric oxidants, ozone and ultra-violet light; and the change in their properties was monitored for different biodiesel blends. Upon the exposure to oxidative agents, the chemical composition of the exhaust changes. It triggers the cascade of photochemical reactions resulting in the partitioning of semi-volatile compounds between the gas and particulate phase. In most of the cases, aging lead to the increase in volatility and oxidative potential, and the increment of change was mainly dependent on the chemical composition of fuels as the leading cause for the amount and the type of semi-volatile compounds present in the exhaust.

  14. On the formation of sulphuric acid-amine clusters in varying atmospheric conditions and its influence on atmospheric new particle formation

    Directory of Open Access Journals (Sweden)

    P. Paasonen

    2012-05-01

    Full Text Available Sulphuric acid is a key component in atmospheric new particle formation. However, sulphuric acid alone does not form stable enough clusters to initiate particle formation in atmospheric conditions. Strong bases, such as amines, have been suggested to stabilize sulphuric acid clusters and thus participate in particle formation. We modelled the formation rate of clusters with two sulphuric acid and two amine molecules (JA2B2 at varying atmospherically relevant conditions with respect to concentrations of sulphuric acid ([H2SO4], dimethylamine ([DMA] and trimethylamine ([TMA], temperature and relative humidity (RH. The modelled formation rates JA2B2 were functions of sulphuric acid concentration with close to quadratic dependence, which is in good agreement with atmospheric observations of the connection between the particle formation rate and sulphuric acid concentration. The coefficients KA2B2 connecting the cluster formation rate and sulphuric acid concentrations as JA2B2 = KA2B2[H2SO4]2 turned out to depend also on amine concentrations, temperature and relative humidity. We tested how the model results change if the clusters with two sulphuric acid and two amine molecules are assumed to act as seeds for heterogeneous nucleation of organic vapours (other than amines with higher atmospheric concentrations than sulphuric acid. We also compared the modelled coefficients KA2B2 with the corresponding coefficients calculated from the atmospheric observations (Kobs from environments with varying temperatures and levels of anthropogenic influence. By taking into account the modelled behaviour of JA2B2 as a function of [H2SO4], temperature and RH, the atmospheric particle formation rate was reproduced more closely than with the

  15. Preparation of Ultrafine Cobalt Powder by Chemical Reduction in Aqueous Solution

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Nanocrystalline cobalt powders have been prepared from aqueous solution by reducing their corresponding metal salts under suitable conditions. The experimental conditions have been studied in detail. X-ray powder diffraction patterns show that the cobalt powder is hexagonal crystallite. The average particle size of the ultrafine cobalt powder is 55 nm.

  16. Future monitoring of charged particle energy deposition into the upper atmosphere and comments on possible relationships between atmospheric phenomena and solar and/or geomagnetic activity

    Science.gov (United States)

    Williams, D. J.; Grubb, R. N.; Evans, D. S.; Sauer, H. H.

    1975-01-01

    Monitoring of earth's atmosphere was conducted for several years utilizing the ITOS series of low-altitude, polar-orbiting weather satellites. A space environment monitoring package was included in these satellites to perform measurements of a portion of earth's charged particle environment. The charged particle observations proposed for the low-altitude weather satellite TIROS N, are described which will provide the capability of routine monitoring of the instantaneous total energy deposition into the upper atmosphere by the precipitation of charged particles from higher altitudes. Such observations may be of use in future studies of the relationships between geomagnetic activity and atmospheric weather pattern developments. Estimates are given to assess the potential importance of this type of energy deposition. Discussion and examples are presented illustrating the importance of distinguishing between solar and geomagnetic activity as possible causative sources. Such differentiation is necessary because of the widely different spatial and time scales involved in the atmospheric energy input resulting from these various sources of activity.

  17. Properties Research of Ultrafine DADNBF%超细 DADNBF 的性能研究

    Institute of Scientific and Technical Information of China (English)

    沈盼盼; 刘祖亮

    2014-01-01

    In order to study the properties of ultrafine 5 ,7-diamino-4 ,6-dinitrobenzenfuroxan (DADNBF) , ultrafine DADNBF was prepared using solvent/non-solvent method .The particle size distribution ,impact sensitivi-ty ,thermal stability ,vacuum stability ,shock sensitivity and flyer sensitivity of ultrafine DADNBF were compara-tively analyzed with raw DADNBF and ultrafine HNS-Ⅳ .The results show that the particle size distribution of ul-trafine DADNBF is in a range of 0 0.35-0 3.16 μm ,the specific surface area is 25 1. m2/g ,and the impact sensitivity (H50 ) is 108cm .The temperature at the exothermic peak of ultrafine DADNBF is 300℃ ,13℃ lower than that of the raw DADNBF .The critical initiation voltage of ultrafine DADNBF in flyer initiation test is 2 .35 kV and the shock sensitivity (X50 ) is 7 .54 mm .The comprehensive properties of ultrafine DADNBF are similar to ultrafine HNS-Ⅳ .%为了研究超细颗粒5,7-二氨基-4,6-二硝基苯并氧化呋咱(DADNBF )的性质,采用溶剂-非溶剂法制备了超细DADNBF颗粒。研究了超细DADNBF的粒径分布、撞击感度、热稳定性、真空安定性、冲击波感度和飞片起爆感度等性能,并与普通DADNBF和超细 HNS-Ⅳ进行比较。研究结果表明:DADNBF超细化后,样品粒度主要分布在00.35~03.16μm范围内;比表面积为251. m2/g ;撞击感度 H 50为108 cm ;DSC分解放热峰温为300℃,比细化前降低13℃;飞片起爆实验最低起爆电压为23.5 kV ;冲击波感度 X50=75.4 mm。超细DADNBF综合性能与超细HNS-Ⅳ接近。

  18. Characterisation of atmospheric deposited particles during a dust storm in urban areas of Eastern Australia.

    Science.gov (United States)

    Gunawardena, Janaka; Ziyath, Abdul M; Bostrom, Thor E; Bekessy, Lambert K; Ayoko, Godwin A; Egodawatta, Prasanna; Goonetilleke, Ashantha

    2013-09-01

    The characteristics of dust particles deposited during the 2009 dust storm in the Gold Coast and Brisbane regions of Australia are discussed in this paper. The study outcomes provide important knowledge in relation to the potential impacts of dust storm related pollution on ecosystem health in the context that the frequency of dust storms is predicted to increase due to anthropogenic desert surface modifications and climate change impacts. The investigated dust storm contributed a large fraction of fine particles to the environment with an increased amount of total suspended solids, compared to dry deposition under ambient conditions. Although the dust storm passed over forested areas, the organic carbon content in the dust was relatively low. The primary metals present in the dust storm deposition were aluminium, iron and manganese, which are common soil minerals in Australia. The dust storm deposition did not contain significant loads of nickel, cadmium, copper and lead, which are commonly present in the urban environment. Furthermore, the comparison between the ambient and dust storm chromium and zinc loads suggested that these metals were contributed to the dust storm by local anthropogenic sources. The potential ecosystem health impacts of the 2009 dust storm include, increased fine solids deposition on ground surfaces resulting in an enhanced capacity to adsorb toxic pollutants as well as increased aluminium, iron and manganese loads. In contrast, the ecosystem health impacts related to organic carbon and other metals from dust storm atmospheric deposition are not considered to be significant.

  19. Attenuated total reflectance FT-IR imaging and quantitative energy dispersive-electron probe X-ray microanalysis techniques for single particle analysis of atmospheric aerosol particles.

    Science.gov (United States)

    Ryu, JiYeon; Ro, Chul-Un

    2009-08-15

    This work demonstrates the practical applicability of the combined use of attenuated total reflectance (ATR) FT-IR imaging and low-Z particle electron probe X-ray microanalysis (EPMA) techniques for the characterization of individual aerosol particles. These two single particle analytical techniques provide complementary information on the physicochemical characteristics of the same individual particles, that is, the low-Z particle EPMA for the information on the morphology and elemental concentration and the ATR-FT-IR imaging on the functional group, molecular species, and crystal structure. It was confirmed that the ATR-FT-IR imaging technique can provide sufficient FT-IR absorption signals to perform molecular speciation of individual particles of micrometer size when applied to artificially generated aerosol particles such as ascorbic acid and NaNO(3) aerosols. An exemplar indoor atmospheric aerosol sample was investigated to demonstrate the practical feasibility of the combined application of ATR-FT-IR imaging and low-Z particle EPMA techniques for the characterization of individual airborne particles.

  20. Are coarse particles unexpected common reservoirs for some atmospheric anthropogenic trace elements? A case study

    Science.gov (United States)

    Catinon, Mickaël; Ayrault, Sophie; Boudouma, Omar; Bordier, Louise; Agnello, Gregory; Reynaud, Stéphane; Tissut, Michel

    2013-08-01

    Without specific experimental equipment, it is very difficult to sample long-term atmospheric deposits on a pure state. That is why the composition of air-transferred solid material accumulated for 40 years in the 2 m-high walls, pierced with numerous holes of an outdoor public shelter, Grenoble city, France, was studied. An appropriate fractionation procedure allowed to obtain several fractions which were i) a sand fraction (8.3%) (fraction A), ii) a large mass of organic matter corresponding mostly to large fragments (>250 μm) of plant origin (66.7%) (fraction B) or to pollen fraction C (0.4%), iii) a slowly depositing organo-clay fraction (20%) (fractions D1 and D2) and iv) a solution mixed with non-settable particles (4.3%) (fraction E). The composition of each fraction was determined for 20 elements. The sand fraction showed very high concentrations specifically in Cu, Pb and Fe corresponding respectively to 81.5, 48.2 and 35.2% of the samples content in these elements. In contrast, Cd and Zn were mainly accumulated in the fraction B (67.5 and 62.2%, respectively). The scanning electron microscopy coupled to energy dispersive X-ray analysis (SEM-EDX) study of the fraction A showed the presence of large particles bearing Pb and Fe, particles rich in Cu and typical fly ashes originating mostly from iron industry. Most of these particles had a crystalline shape suggesting that they were formed after emission at a high temperature. The Pb-Fe-Cu deposit seen in fraction A likely originates from the neighbouring road surface contaminated by car traffic for several decades. The 206Pb/207Pb ratio (1.146 ± 0.004) showed that in the coarse sandy fraction A, Pb was represented at 65% by non-gasoline lead and 35% by "gasoline" lead emitted before 1999. The fraction A particles can only be transported on a limited distance by high magnitude events. They constitute a large reservoir for Cu and Pb and may play a major role in the long-term contamination of urban soils.

  1. Highly time-resolved chemical characterization of atmospheric fine particles during 2010 Shanghai World Expo

    Directory of Open Access Journals (Sweden)

    X.-F. Huang

    2012-01-01

    Full Text Available Shanghai, with a population of over 20 million, is the largest mega-city in China. Rapidly increasing industrial and metropolitan emissions have deteriorated its air quality in the past decades, with fine particle pollution as one of the major issues. However, systematic characterization of atmospheric fine particles with advanced measurement techniques has been very scarce in Shanghai. During 2010 Shanghai World Expo, we deployed a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS and a single particle soot photometer (SP2 in urban Shanghai between 15 May and 10 June 2010 to measure fine particles with a high time resolution. The 4-min resolution PM1 mass concentration ranged from 5.5 to 155 μg m−3, with an average of 29.2 μg m−3. On average, sulfate and organic matter (OM were the most abundant PM1 components, accounting for 33.3 and 28.7% of the total mass, respectively, while the fraction of nitrate showed an increasing trend with the increasing PM1 loading, indicating the photochemical nature of high fine particle pollution in Shanghai. Taking advantage of HR-ToF-AMS and SP2, OM was found to have an average OM/OC ratio (organic matter mass/organic carbon mass of 1.55 and black carbon (BC had an average number fraction of internally mixed BC of 41.2%. Positive matrix factorization (PMF analysis on the high resolution organic mass spectral dataset identified a hydrocarbon-like (HOA, a semi-volatile oxygenated (SV-OOA, and a low-volatility oxygenated (LV-OOA organic aerosol component, which on average accounted for 24.0, 46.8, and 29.2% of the total organic mass, respectively. The diurnal patterns of them with interesting time delay possibly implied a photochemical oxidizing process from HOA (and/or its concurrently emitted gaseous organic pollutants to SV-OOA to LV-OOA. Back trajectory analysis indicated that the northwesterly continental air mass represented the

  2. Highly time-resolved chemical characterization of atmospheric fine particles during 2010 Shanghai World Expo

    Directory of Open Access Journals (Sweden)

    X.-F. Huang

    2012-06-01

    Full Text Available Shanghai, with a population of over 20 million, is the largest mega-city in China. Rapidly increasing industrial and metropolitan emissions have deteriorated its air quality in the past decades, with fine particle pollution as one of the major issues. However, systematic characterization of atmospheric fine particles with advanced measurement techniques has been very scarce in Shanghai. During 2010 Shanghai World Expo, we deployed a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS and a single particle soot photometer (SP2 in urban Shanghai between 15 May and 10 June 2010 to measure fine particles with a high time resolution. The 4-min resolution PM1 mass concentration ranged from 5.5 to 155 μg m−3, with an average of 29.2 μg m−3. On average, sulfate and organic matter (OM were the most abundant PM1 components, accounting for 33.3 and 28.7% of the total mass, respectively, while the fraction of nitrate showed an increasing trend with the increasing PM1 loading, indicating the photochemical nature of high fine particle pollution in Shanghai. Taking advantage of HR-ToF-AMS and SP2, OM was found to have an average OM/OC ratio (organic matter mass/organic carbon mass of 1.55 and black carbon (BC had an average number fraction of internally mixed BC of 41.2%. Positive matrix factorization (PMF analysis on the high resolution organic mass spectral dataset identified a hydrocarbon-like (HOA, a semi-volatile oxygenated (SV-OOA, and a low-volatility oxygenated (LV-OOA organic aerosol component, which on average accounted for 24.0, 46.8, and 29.2% of the total organic mass, respectively. The diurnal patterns of them with interesting time delay possibly implied a photochemical oxidizing process from HOA (and/or its concurrently emitted gaseous organic pollutants to SV-OOA to LV-OOA. Back trajectory analysis indicated that the northwesterly continental air mass represented the

  3. Atmospheric heteroseneous reaction of acetone: Adsorption and desorption kinetics and mechanisms on SiO2 particles

    Institute of Scientific and Technical Information of China (English)

    JIE ChongYu; CHEN ZhongMing; WANG HongLi; HUA Wei; WANG CaiXia; LI Shuang

    2008-01-01

    Acetone plays an important role in photooxidation processes in the atmosphere. Up to date, little is known regarding the heterogeneous fate of acetone. In this study, the adsorption and desorption processes of acetone on SiO2 particles, which are the major constituent of mineral dust in the atmos-phere, have been investigated for the first time under the simulated atmospheric conditions, using in situ transmission Fourier transform infrared spectroscopy. It is found that acetone molecules are ad-sorbed on the surfaces of SiO2 particles by van der Waals forces and hydrogen bonding forces in a nonreactive and reversible state. The rates of initial adsorption and initial desorption, initial uptake coefficients and adsorption concentrations at equilibrium have been determined at different relative humidity. The presence of water vapor cannot result in the formation of new substances, but can de-crease the adsorption ability by consuming or overlapping the isolated OH groups on the surfaces of SiO2 particles. In the desorption process, a considerable amount of acetone molecules will remain on SiO2 particles in dry air, whereas acetone molecules are almost completely desorbed at a high relative humidity. In order to evaluate the role of heterogeneous reactions of acetone and other carbonyl compounds in the atmosphere, a new model fitting the atmospheric conditions is needed.

  4. Investigation of particle sizes in Pluto's atmosphere from the 29 June 2015 occultation

    Science.gov (United States)

    Sickafoose, Amanda A.; Bosh, A. S.; Person, M. J.; Zuluaga, C. A.; Levine, S. E.; Pasachoff, J. M.; Babcock, B. A.; Dunham, E. W.; McLean, I.; Wolf, J.; Abe, F.; Bida, T. A.; Bright, L. P.; Brothers, T.; Christie, G.; Collins, P. L.; Durst, R. F.; Gilmore, A. C.; Hamilton, R.; Harris, H. C.; Johnson, C.; Kilmartin, P. M.; Kosiarek, M. R.; Leppik, K.; Logsdon, S.; Lucas, R.; Mathers, S.; Morley, C. J. K.; Natusch, T.; Nelson, P.; Ngan, H.; Pfüller, E.; de, H.-P.; Sallum, S.; Savage, M.; Seeger, C. H.; Siu, H.; Stockdale, C.; Suzuki, D.; Thanathibodee, T.; Tilleman, T.; Tristam, P. J.; Van Cleve, J.; Varughese, C.; Weisenbach, L. W.; Widen, E.; Wiedemann, M.

    2015-11-01

    The 29 June 2015 observations of a stellar occultation by Pluto, from SOFIA and ground-based sites in New Zealand, indicate that haze was present in the lower atmosphere (Bosh et al., this conference). Previously, slope changes in the occultation light curve profile of Pluto’s lower atmosphere have been attributed to haze, a steep thermal gradient, and/or a combination of the two. The most useful diagnostic for differentiating between these effects has been observing occultations over a range of wavelengths: haze scattering and absorption are functions of particle size and are wavelength dependent, whereas effects due to a temperature gradient should be largely independent of observational wavelength. The SOFIA and Mt. John data from this event exhibit obvious central flashes, from multiple telescopes observing over a range of wavelengths at each site (Person et al. and Pasachoff et al., this conference). SOFIA data include Red and Blue observations from the High-speed Imaging Photometer for Occultations (HIPO, at ~ 500 and 850 nm), First Light Infrared Test Camera (FLITECAM, at ~1800 nm), and the Focal Plan Imager (FPI+, at ~ 600 nm). Mt. John data include open filter, g', r', i', and near infrared. Here, we analyze the flux at the bottom of the light curves versus observed wavelength. We find that there is a distinct trend in flux versus wavelength, and we discuss applicable Mie scattering models for different particle size distributions and compositions (as were used to characterize haze in Pluto's lower atmosphere in Gulbis et al. 2015).SOFIA is jointly operated by the Universities Space Research Association, Inc. (USRA), under NASA contract NAS2-97001, and the Deutsches SOFIA Institut (DSI) under DLR contract 50 OK 0901 to the University of Stuttgart. Support for this work was provided by the National Research Foundation of South Africa, NASA SSO grants NNX15AJ82G (Lowell Observatory), PA NNX10AB27G (MIT), and PA NNX12AJ29G (Williams College), and the NASA

  5. Aerosol and Cloud-Nucleating Particle Observations during an Atmospheric River Event

    Science.gov (United States)

    DeMott, P. J.; McCluskey, C. S.; Petters, M.; Suski, K. J.; Levin, E. J.; Hill, T. C. J.; Atwood, S. A.; Schill, G. P.; Rocci, K.; Boose, Y.; Martin, A.; Cornwell, G.; Al-Mashat, H.; Moore, K.; Prather, K. A.; Rothfuss, N.; Taylor, H.; Leung, L. R.; Tomlinson, J. M.; Mei, F.; Hubbe, J. M.; Rosenfeld, D.; Spackman, J. R.; Fairall, C. W.; Creamean, J.; White, A. B.; Kreidenweis, S. M.

    2015-12-01

    The multi-agency CalWater 2015 project occurred over North Central CA and the Eastern Pacific during January to March 2015 (Spackman et al., this session). The goals of the campaign were to document the structure of atmospheric rivers (ARs) that deliver much of the water vapor associated with major winter storms along the U.S. West Coast and to investigate the modulating effect of aerosols on precipitation. Aerosol sources that may influence orographic cloud properties for air lifted over the mountains in California in winter include pollution, biomass burning, soil dusts and marine aerosols, but their roles will also be influenced by transport, vertical stratification, and scavenging processes. We present results from a comprehensive study of aerosol distributions, compositions, and cloud nucleating properties during an intense winter storm during February 2015, including data from an NSF-supported measurement site at Bodega Bay, from the DOE-ARM Cloud Aerosol Precipitation Experiment that included sampling on the NOAA RV Ron Brown offshore and the G-1 aircraft over ocean and land, and with context provided by other NOAA aircraft and remote sensing facilities. With a special focus on the coastal site, we discuss changes in aerosol distributions, aerosol hygroscopicity, and number concentrations of fluorescent particles, cloud condensation nuclei (CCN), and ice nucleating particles (INPs) during the AR event. We compare with periods preceding and following the event. For example, total aerosol number and surface area concentrations at below 0.5 μm diameter decreased from typical values of a few thousand cm-3 and 100 μm2 cm-3, respectively, to a few hundred cm-3 and 10 μm2cm-3 at Bodega Bay during the AR event. CCN concentrations were similarly lower, but hygroscopicity parameter (kappa) increased from typical values of 0.2 to values > 0.5 during the AR.INP and fluorescent particle number concentrations were generally lower during the AR event than at any other

  6. Real time analysis of lead-containing atmospheric particles in Beijing during springtime by single particle aerosol mass spectrometry.

    Science.gov (United States)

    Ma, Li; Li, Mei; Huang, Zhengxu; Li, Lei; Gao, Wei; Nian, Huiqing; Zou, Lilin; Fu, Zhong; Gao, Jian; Chai, Fahe; Zhou, Zhen

    2016-07-01

    Using a single particle aerosol mass spectrometer (SPAMS), the chemical composition and size distributions of lead (Pb)-containing particles with diameter from 0.1 μm to 2.0 μm in Beijing were analyzed in the spring of 2011 during clear, hazy, and dusty days. Based on mass spectral features of particles, cluster analysis was applied to Pb-containing particles, and six major classes were acquired consisting of K-rich, carboneous, Fe-rich, dust, Pb-rich, and Cl-rich particles. Pb-containing particles accounted for 4.2-5.3%, 21.8-22.7%, and 3.2% of total particle number during clear, hazy and dusty days, respectively. K-rich particles are a major contribution to Pb-containing particles, varying from 30.8% to 82.1% of total number of Pb-containing particles, lowest during dusty days and highest during hazy days. The results reflect that the chemical composition and amount of Pb-containing particles has been affected by meteorological conditions as well as the emissions of natural and anthropogenic sources. K-rich particles and carbonaceous particles could be mainly assigned to the emissions of coal combustion. Other classes of Pb-containing particles may be associated with metallurgical processes, coal combustion, dust, and waste incineration etc. In addition, Pb-containing particles during dusty days were first time studied by SPAMS. This method could provide a powerful tool for monitoring and controlling of Pb pollution in real time.

  7. Adsorption of phenol from water by ultrafine coal powders

    Institute of Scientific and Technical Information of China (English)

    LIU Zhuan-nian; ZHOU An-ning; YANG Fan; JIN Qi-ting

    2007-01-01

    Seven Shenfu coal powders different in particle size obtained by sieving and ball milling were used to probe their adsorption properties to phenol from water.The results show that the kinetics of phenol on coal powders follow the second-Order adsorption kinetic model well.Adsorption processes are governed by film diffusion and the kinetic parameters and the effective diffusion coefficients were calculated through plotting.Adsorption capacities to phenol increase exponentially with decreasing of diameter of coal described in terms of Freundlich isotherm,while for ultrafine coal powders with d50 of 4.28and 4.82 μm fit Langmuir isotherm well.

  8. Facile Fabrication of Ultrafine Copper Nanoparticles in Organic Solvent

    Directory of Open Access Journals (Sweden)

    Siegert Uwe

    2009-01-01

    Full Text Available Abstract A facile chemical reduction method has been developed to fabricate ultrafine copper nanoparticles whose sizes can be controlled down to ca. 1 nm by using poly(N-vinylpyrrolidone (PVP as the stabilizer and sodium borohyrdride as the reducing agent in an alkaline ethylene glycol (EG solvent. Transmission electron microscopy (TEM results and UV–vis absorption spectra demonstrated that the as-prepared particles were well monodispersed, mostly composed of pure metallic Cu nanocrystals and extremely stable over extended period of simply sealed storage.

  9. Characteristics of atmospheric particulate mercury in size-fractionated particles during haze days in Shanghai

    Science.gov (United States)

    Chen, Xiaojia; Balasubramanian, Rajasekhar; Zhu, Qiongyu; Behera, Sailesh N.; Bo, Dandan; Huang, Xian; Xie, Haiyun; Cheng, Jinping

    2016-04-01

    Atmospheric particulate mercury (PHg) is recognized as a global pollutant that requires regulation because of its significant impacts on both human health and wildlife. The haze episodes that occur frequently in China could influence the transport and fate of PHg. To examine the characteristics of PHg during haze and non-haze days, size-fractioned particles were collected using thirteen-stage Nano-MOUDI samplers (10 nm-18 μm) during a severe haze episode (from December 2013 to January 2014) in Shanghai. The PHg concentration on haze days (4.11 ± 0.53 ng m-3) was three times higher than on non-haze days (1.34 ± 0.15 ng m-3). The ratio of the PHg concentration to total gaseous mercury (TGM) ranged from 0.42 during haze days to 0.21 during non-haze days, which was possibly due to the elevated concentration of particles for gaseous elemental mercury (GEM) adsorption, elevated sulfate and nitrate contributing to GEM oxidation, and the catalytic effect of elevated water-soluble inorganic metal ions. PHg/PM10 during haze days (0.019 ± 0.004 ng/μg) was lower than during non-haze days (0.024 ± 0.002 ng/μg), and PHg/PM10 was significantly reduced with an increasing concentration of PM10, which implied a relatively lower growth velocity of mercury than other compositions on particles during haze days, especially in the diameter range of 0.018-0.032 μm. During haze days, each size-fractioned PHg concentration was higher than the corresponding fraction on non-haze days, and the dominant particle size was in the accumulation mode, with constant accumulation to a particle size of 0.56-1.0 μm. The mass size distribution of PHg was bimodal with peaks at 0.32-0.56 μm and 3.1-6.2 μm on non-haze days, and 0.56-1.0 μm and 3.1-6.2 μm on haze days. There was a clear trend that the dominant size for PHg in the fine modes shifted from 0.32-0.56 μm during non-haze days to 0.56-1.0 μm on haze days, which revealed the higher growth velocity of PHg on haze days due to the

  10. Preparation of ultrafine Ce-based oxide nanoparticles and their catalytic performances for diesel soot combustion

    Institute of Scientific and Technical Information of China (English)

    韦岳长; 赵震; 焦金庆; 刘坚; 段爱军; 姜桂元

    2014-01-01

    The ultrafine Ce-based oxide nanoparticles with different element dopings (Zr, Y) were synthesized by the method of mi-cropores-diffused coprecipitation (MDC) using ammonia solution as the precipitation agent. The activities of the catalysts for soot oxidation were evaluated by the temperature-programmed oxidation (TPO) reaction. Ce-based oxides prepared in this study exhibited high catalytic activity for soot oxidation under the condition of loose contact between soot particles and catalysts, and the catalytic ac-tivity of ultrafine Ce0.9Zr0.1O2 nanoparticle for soot combustion was the highest, whose T10, T50 and SCO2m was 364, 442 ºC and 98.3%, respectively. All catalysts were systematically characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brumauer-Emett-Teller (BET), Fourier transform infrared spectroscopy (FT-IR) and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS). It was indicated that the MDC method could prepare the ultrafine Ce-based oxide nanoparticles whose the crystal lattice were perfect, and the BET surface area and average crystal size of the ultrafine nanoparticles changed with the different element dopings (Zr, Y). The H2-TPR measurements showed that the ultrafine Ce-based ox-ide nanoparticles with the doping-Zr cation could be favorable for improving the redox property of the catalysts.

  11. Selective Flocculation Enhanced Magnetic Separation of Ultrafine Disseminated Magnetite Ores

    Directory of Open Access Journals (Sweden)

    Tao Su

    2016-08-01

    Full Text Available Simple magnetic separation for a certain magnetite mine with ultrafine disseminated lean ores has resulted in low performance, as the fine sizes and aggregation of ground mineral particles have caused inefficient recovery of the ultrafine minerals. In this study, we attempt to increase the apparent sizes of target mineral particles, and improve the separation indices, by using a multi-stage grinding-dispersion-selective flocculation-weak magnetic separation process. The results showed that under the conditions of 500 g/t sodium hexametaphospate (SHMP as dispersant, 750 g/t carboxymethyl starch (CMS as flocculant, agitating at 400 rpm for 10 min, with slurry pH 11, and final grinding fineness of 93.5% less than 0.03 mm, the obtained concentrate contained 62.82% iron, with recovery of 79.12% after multi-stage magnetic separation. Compared to simple magnetic separation, the concentrate’s iron grade increased by 1.26%, and a recovery rate by 5.08%. Fundamental analysis indicated that, in a dispersed state of dispersion, magnetite particles had weaker negative surface charges than quartz, allowing the adsorption of negative CMS ions via hydrogen bonding. Consequently, the aggregate size of the initial concentrate increased from 24.30 to 38.37 μm, accomplishing the goal of selective flocculation, and increasing the indices of separation.

  12. ISSARS Aerosol Database : an Incorporation of Atmospheric Particles into a Universal Tool to Simulate Remote Sensing Instruments

    Science.gov (United States)

    Goetz, Michael B.

    2011-01-01

    The Instrument Simulator Suite for Atmospheric Remote Sensing (ISSARS) entered its third and final year of development with an overall goal of providing a unified tool to simulate active and passive space borne atmospheric remote sensing instruments. These simulations focus on the atmosphere ranging from UV to microwaves. ISSARS handles all assumptions and uses various models on scattering and microphysics to fill the gaps left unspecified by the atmospheric models to create each instrument's measurements. This will help benefit mission design and reduce mission cost, create efficient implementation of multi-instrument/platform Observing System Simulation Experiments (OSSE), and improve existing models as well as new advanced models in development. In this effort, various aerosol particles are incorporated into the system, and a simulation of input wavelength and spectral refractive indices related to each spherical test particle(s) generate its scattering properties and phase functions. These atmospheric particles being integrated into the system comprise the ones observed by the Multi-angle Imaging SpectroRadiometer(MISR) and by the Multiangle SpectroPolarimetric Imager(MSPI). In addition, a complex scattering database generated by Prof. Ping Yang (Texas A&M) is also incorporated into this aerosol database. Future development with a radiative transfer code will generate a series of results that can be validated with results obtained by the MISR and MSPI instruments; nevertheless, test cases are simulated to determine the validity of various plugin libraries used to determine or gather the scattering properties of particles studied by MISR and MSPI, or within the Single-scattering properties of tri-axial ellipsoidal mineral dust particles database created by Prof. Ping Yang.

  13. Chemical characteristics and source apportionment of atmospheric particles during heating period in Harbin, China

    Institute of Scientific and Technical Information of China (English)

    Likun Huang; Guangzhi Wang

    2014-01-01

    Atmospheric particles (total suspended particles (TSPs); particulate matter (PM) with particle size below 10 μm,PM10; particulate matter with particle size below 2.5 μm,PM2.5)were collected and analyzed during heating and non-heating periods in Harbin.The sources of PM10 and PM2.5 were identified by the chemical mass balance (CMB) receptor model.Results indicated that PM2.5/TSP was the most prevalent and PM2.5 was the main component of PM10,while the presence of PM10-100 was relatively weak.SC42-and NO3-concentrations were more significant than other ions during the heating period.As compared with the non-heating period,Mn,Ni,Pb,S,Si,Ti,Zn,As,Ba,Cd,Cr,Fe and K were relatively higher during the heating period.In particular,Mn,Ni,S,Si,Ti,Zn and As in PM2.5 were obviously higher during the heating period.Organic carbon (OC) in the heating period was 2-5 times higher than in the non-heating period.Elemental carbon (EC) did not change much.OC/EC ratios were 8-11 during the heating period,which was much higher than in other Chinese cities (OC/EC:4-6).Results from the CMB indicated that 11 pollution sources were identified,of which traffic,coal combustion,secondary sulfate,secondary nitrate,and secondary organic carbon made the greatest contnbution.Before the heating period,dust and petrochemical industry made a larger contribution.In the heating period,coal combustion and secondary sulfate were higher.After the heating period,dust and petrochemical industry were highen Some hazardous components in PM2.5 were higher than in PM10,because PM2.5 has a higher ability to absorb toxic substances.Thus PM2.5 pollution is more significant regarding human health effects in the heating period.

  14. Health Impacts Estimation of Mineralogical and Chemical Characterization of Suspended Atmospheric Particles over the East Desert

    Directory of Open Access Journals (Sweden)

    U. A. Rahoma

    2010-01-01

    Full Text Available Problem statement: The small size fraction of aerosols, measured as PM10 and PM2.5, rather than the larger particles, is considered to be responsible for most of the health effects. Such particles have a relatively long residence time in the atmosphere and can therefore travel over long distances. Hence, a large portion of ambient concentrations of PM10 and in particular of particles with an aerodynamic diameter less than 2.5 µm (PM2.5, can be attributed to long range trans boundary air pollution or to other remote sources. The estimates of exposure and of health effects are based on a number of uncertain assumptions and data sets, as described in previous article. Approach: In industrialized Middle East countries, the daily deposition of PM10 particles in the lungs is roughly 250 µg day-1, which represents a small dose in terms of traditional toxicology studies. Studies of PM10 have considered this total material but have not asked how much its chemical or physical characteristics contribute to its total toxicity. Results: This article focuses on the description of the present knowledge on PM10 concentration fields and predominant sources contributing to PM10 from long range transport of pollution. PM10 is a complex mixture of many known and unknown components; therefore, a short introduction on the composition of PM10 is given. The studies denote to the African dust from mean PM10 levels background levels are still 5-10 mg m3 higher in the Eastern Basin (EMB when compared with those in the Western (WMB, mainly due to the higher anthropogenic and sea spray loads. Conclusion: As regards for the seasonal trends, these are largely driven by the occurrence of African dust events, resulting in a spring-early summer maximum over the EMB and a clear summer maximum in the WMB, although in this later region the recirculation of aged air masses play an important role. Furthermore, a marked seasonal trend is still evident when subtracting the African

  15. Preparation of ultrafine a-Al2O3 using precipitation-azeotropic distillation method

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Ammonium aluminum carbonate hydroxide (AACH) was prepared by a precipitation-azeotropic distillation method,which uses aluminum sulfate as the Al source and ammonium carbonate as the precipitant.Then,AACH was calcined into ultrafine α-Al2O3 powder.The factors that influence the dispersion property of ultrafine α-Al2O3 powder are discussed in this paper,such as the methods of adding materials,surfactant,and drying methods.The changes of the structure and property of ultrafine alumina in the thermal treatment process are also studied.The morphological structure and properties of AACH are characterized by DTA/TGA,SEM,XRD,and ICP measurements.The results show that ultrafine α-Al2O3 powder with a uniform particle size and well-distributed property can be synthesized only after aluminum sulfate atomizes into ammonium carbonate,proper amount of PEG1000 is added as the dispersant,and the product is treated by azeotropic distillation.The phase transformation of alumina during the calcination process can be described as amorphous Al2O3→γ-Al2O3→θ-Al2O3→α-Al2O3.The crystal grain size and density of ultrafine alumina powder increase with the increase of the calcination temperature.After AACH has been calcined at 1200℃ for 2 h,the ultrafine α-Al2O3 with uniform particle size,spherical shape,and more than 99.97% purity is obtained and its powder is well dispersed.

  16. Photochemistry of iron(III)-carboxylato complexes in aqueous atmospheric particles - Laboratory experiments and modeling studies

    Science.gov (United States)

    Weller, C.; Tilgner, A.; Herrmann, H.

    2010-12-01

    Iron is always present in the atmosphere in concentrations from ~10-9 M (clouds, rain) up to ~10-3 M (fog, particles). Sources are mainly mineral dust emissions. Iron complexes are very good absorbers in the UV-VIS actinic region and therefore photo-chemically reactive. Iron complex photolysis leads to radical production and can initiate radical chain reactions, which is related to the oxidizing capacity of the atmosphere. These radical chain reactions are involved in the decomposition and transformation of a variety of chemical compounds in cloud droplets and deliquescent particles. Additionally, the photochemical reaction itself can be a degradation pathway for organic compounds with the ability to bind iron. Iron-complexes of atmospherically relevant coordination compounds like oxalate, malonate, succinate, glutarate, tartronate, gluconate, pyruvate and glyoxalate have been investigated in laboratory experiments. Iron speciation depends on the iron-ligand ratio and the pH. The most suitable experimental conditions were calculated with a speciation program (Visual Minteq). The solutions were prepared accordingly and transferred to a 1 cm quartz cuvette and flash-photolyzed with an excimer laser at wavelengths 308 or 351 nm. Photochemically produced Fe2+ has been measured by spectrometry at 510 nm as Fe(phenantroline)32+. Fe2+ overall effective quantum yields have been calculated with the concentration of photochemically produced Fe2+ and the measured energy of the excimer laser pulse. The laser pulse energy was measured with a pyroelectric sensor. For some iron-carboxylate systems the experimental parameters like the oxygen content of the solution, the initial Iron concentration and the incident laser energy were systematically altered to observe an effect on the overall quantum yield. The dependence of some quantum yields on these parameters allows in some cases an interpretation of the underlying photochemical reaction mechanism. Quantum yields of malonate

  17. Seasonal variation of atmospheric particle number concentrations, new particle formation and atmospheric oxidation capacity at the high Arctic site Villum Research Station, Station Nord

    Science.gov (United States)

    Nguyen, Quynh T.; Glasius, Marianne; Sørensen, Lise L.; Jensen, Bjarne; Skov, Henrik; Birmili, Wolfram; Wiedensohler, Alfred; Kristensson, Adam; Nøjgaard, Jacob K.; Massling, Andreas

    2016-09-01

    This work presents an analysis of the physical properties of sub-micrometer aerosol particles measured at the high Arctic site Villum Research Station, Station Nord (VRS), northeast Greenland, between July 2010 and February 2013. The study focuses on particle number concentrations, particle number size distributions and the occurrence of new particle formation (NPF) events and their seasonality in the high Arctic, where observations and characterization of such aerosol particle properties and corresponding events are rare and understanding of related processes is lacking.A clear accumulation mode was observed during the darker months from October until mid-May, which became considerably more pronounced during the prominent Arctic haze months from March to mid-May. In contrast, nucleation- and Aitken-mode particles were predominantly observed during the summer months. Analysis of wind direction and wind speed indicated possible contributions of marine sources from the easterly side of the station to the observed summertime particle number concentrations, while southwesterly to westerly winds dominated during the darker months. NPF events lasting from hours to days were mostly observed from June until August, with fewer events observed during the months with less sunlight, i.e., March, April, September and October. The results tend to indicate that ozone (O3) might be weakly anti-correlated with particle number concentrations of the nucleation-mode range (10-30 nm) in almost half of the NPF events, while no positive correlation was observed. Calculations of air mass back trajectories using the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model for the NPF event days suggested that the onset or interruption of events could possibly be explained by changes in air mass origin. A map of event occurrence probability was computed, indicating that southerly air masses from over the Greenland Sea were more likely linked to those events.

  18. Mercury isotopes of atmospheric particle bound mercury for source apportionment study in urban Kolkata, India

    Directory of Open Access Journals (Sweden)

    Reshmi Das

    2016-04-01

    Full Text Available Abstract The particle bound mercury (PBM in urban-industrial areas is mainly of anthropogenic origin, and is derived from two principal sources: Hg bound to particulate matter directly emitted by industries and power generation plants, and adsorption of gaseous elemental mercury (GEM and gaseous oxidized mercury (GOM on air particulates from gas or aqueous phases. Here, we measured the Hg isotope composition of PBM in PM10 samples collected from three locations, a traffic junction, a waste incineration site and an industrial site in Kolkata, the largest metropolis in Eastern India. Sampling was carried out in winter and monsoon seasons between 2013–2015. The objective was to understand whether the isotope composition of the PBM represents source composition. The PBM collected from the waste burning site showed little mass independent fractionation (MIF (Δ199Hg = +0.12 to -0.11‰, similar to the signature in liquid Hg and Hg ores around the world with no seasonal variations. Samples from the industrial site showed mostly negative MDF and MIF (δ202Hg = -1.34 to -3.48 ‰ and Δ199Hg = +0.01 to -0.31‰. The MDF is consistent with PBM generated by coal combustion however, the MIF is 0.15‰ more negative compared to the Hg isotope ratios in Indian coals. The traffic junction PBM is probably not produced in situ, but has travelled some distances from nearby industrial sources. The longer residence time of this PBM in the atmosphere has resulted in-aerosol aqueous photoreduction. Thus, the MIF displays a larger range (Δ199Hg = +0.33 to -0.30‰ compared to the signature from the other sites and with more positive values in the humid monsoon season. Different Hg isotopic signature of PBM in the three different sampling locations within the same city indicates that both source and post emission atmospheric transformations play important roles in determining isotopic signature of PBM.

  19. ULTRAFINE FLUORESCENT DIAMONDS IN NANOTECHNOLOGY

    Directory of Open Access Journals (Sweden)

    Kanyuk M. I.

    2014-07-01

    Full Text Available The purpose of the work is to summarize the literature data concerning ultrafine diamonds, namely their industrial production, as well as considerable photostability and biocompatibility that promote their use in modern visualization techniques. It is shown that due to the unique physical properties, they are promising materials for using in nanotechnology in the near future. Possibility of diverse surface modification, small size and large absorption surface are the basis for their use in different approaches for drug and gene delivery into a cell. The changes in the properties of nanodiamond surface modification methods of their creation, stabilization and applications are described. It can be said that fluorescent surface-modified nanodiamonds are a promising target in various research methods that would be widely used for labeling of living cells, as well as in the processes of genes and drugs delivery into a cell.

  20. A critical evaluation of proxy methods used to estimate the acidity of atmospheric particles

    Science.gov (United States)

    Hennigan, C. J.; Izumi, J.; Sullivan, A. P.; Weber, R. J.; Nenes, A.

    2015-03-01

    Given significant challenges with available measurements of aerosol acidity, proxy methods are frequently used to estimate the acidity of atmospheric particles. In this study, four of the most common aerosol acidity proxies are evaluated and compared: (1) the ion balance method, (2) the molar ratio method, (3) thermodynamic equilibrium models, and (4) the phase partitioning of ammonia. All methods are evaluated against predictions of thermodynamic models and against direct observations of aerosol-gas equilibrium partitioning acquired in Mexico City during the Megacity Initiative: Local and Global Research Objectives (MILAGRO) study. The ion balance and molar ratio methods assume that any deficit in inorganic cations relative to anions is due to the presence of H+ and that a higher H+ loading and lower cation / anion ratio both correspond to increasingly acidic particles (i.e., lower pH). Based on the MILAGRO measurements, no correlation is observed between H+ levels inferred with the ion balance and aerosol pH predicted by the thermodynamic models and NH3-NH4+ partitioning. Similarly, no relationship is observed between the cation / anion molar ratio and predicted aerosol pH. Using only measured aerosol chemical composition as inputs without any constraint for the gas phase, the E-AIM (Extended Aerosol Inorganics Model) and ISORROPIA-II thermodynamic equilibrium models tend to predict aerosol pH levels that are inconsistent with the observed NH3-NH4+ partitioning. The modeled pH values from both E-AIM and ISORROPIA-II run with gas + aerosol inputs agreed well with the aerosol pH predicted by the phase partitioning of ammonia. It appears that (1) thermodynamic models constrained by gas + aerosol measurements and (2) the phase partitioning of ammonia provide the best available predictions of aerosol pH. Furthermore, neither the ion balance nor the molar ratio can be used as surrogates for aerosol pH, and previously published studies with conclusions based

  1. A critical evaluation of proxy methods used to estimate the acidity of atmospheric particles

    Directory of Open Access Journals (Sweden)

    C. J. Hennigan

    2014-11-01

    Full Text Available Given significant challenges with available measurements of aerosol acidity, proxy methods are frequently used to estimate the acidity of atmospheric particles. In this study, four of the most common aerosol acidity proxies are evaluated and compared: (1 the ion balance method, (2 the molar ratio method, (3 thermodynamic equilibrium models, and (4 the phase partitioning of ammonia. All methods are evaluated against predictions of thermodynamic models and against direct observations of aerosol-gas equilibrium partitioning acquired in Mexico City during the MILAGRO study. The ion balance and molar ratio methods assume that any deficit in inorganic cations relative to anions is due to the presence of H+; and that a higher H+ loading and lower cation/anion ratio both correspond to increasingly acidic particles (i.e., lower pH. Based on the MILAGRO measurements, no correlation is observed between H+ levels inferred with the ion balance and aerosol pH predicted by the thermodynamic models and ammonia–ammonium (NH3–NH4+ partitioning. Similarly, no relationship is observed between the cation / anion molar ratio and predicted aerosol pH. Using only measured aerosol chemical composition as inputs without any constraint for the gas phase, the Extended Aerosol Inorganics Model (E-AIM and ISORROPIA-II thermodynamic equilibrium models tend to predict aerosol pH levels that are inconsistent with the observed NH3–NH4+ partitioning. The modeled pH values from both models run with gas + aerosol inputs agreed well with the aerosol pH predicted by the phase partitioning of ammonia. It appears that (1 thermodynamic models constrained by gas + aerosol measurements, and (2 the phase partitioning of ammonia provide the best available predictions of aerosol pH. Furthermore, neither the ion balance nor the molar ratio can be used as surrogates for aerosol pH, and published studies to date with conclusions based on such acidity proxies may need to be reevaluated

  2. Organic and inorganic decomposition products from the thermal desorption of atmospheric particles

    Science.gov (United States)

    Williams, Brent J.; Zhang, Yaping; Zuo, Xiaochen; Martinez, Raul E.; Walker, Michael J.; Kreisberg, Nathan M.; Goldstein, Allen H.; Docherty, Kenneth S.; Jimenez, Jose L.

    2016-04-01

    Atmospheric aerosol composition is often analyzed using thermal desorption techniques to evaporate samples and deliver organic or inorganic molecules to various designs of detectors for identification and quantification. The organic aerosol (OA) fraction is composed of thousands of individual compounds, some with nitrogen- and sulfur-containing functionality and, often contains oligomeric material, much of which may be susceptible to decomposition upon heating. Here we analyze thermal decomposition products as measured by a thermal desorption aerosol gas chromatograph (TAG) capable of separating thermal decomposition products from thermally stable molecules. The TAG impacts particles onto a collection and thermal desorption (CTD) cell, and upon completion of sample collection, heats and transfers the sample in a helium flow up to 310 °C. Desorbed molecules are refocused at the head of a gas chromatography column that is held at 45 °C and any volatile decomposition products pass directly through the column and into an electron impact quadrupole mass spectrometer. Analysis of the sample introduction (thermal decomposition) period reveals contributions of NO+ (m/z 30), NO2+ (m/z 46), SO+ (m/z 48), and SO2+ (m/z 64), derived from either inorganic or organic particle-phase nitrate and sulfate. CO2+ (m/z 44) makes up a major component of the decomposition signal, along with smaller contributions from other organic components that vary with the type of aerosol contributing to the signal (e.g., m/z 53, 82 observed here for isoprene-derived secondary OA). All of these ions are important for ambient aerosol analyzed with the aerosol mass spectrometer (AMS), suggesting similarity of the thermal desorption processes in both instruments. Ambient observations of these decomposition products compared to organic, nitrate, and sulfate mass concentrations measured by an AMS reveal good correlation, with improved correlations for OA when compared to the AMS oxygenated OA (OOA

  3. Hygroscopicity of aerosol particles and CCN activity of nearly hydrophobic particles in the urban atmosphere over Japan during summer

    Science.gov (United States)

    Ogawa, Shuhei; Setoguchi, Yoshitaka; Kawana, Kaori; Nakayama, Tomoki; Ikeda, Yuka; Sawada, Yuuki; Matsumi, Yutaka; Mochida, Michihiro

    2016-06-01

    We investigated the hygroscopicity of 150 nm particles and the number-size distributions and the cloud condensation nuclei (CCN) activity of nearly hydrophobic particles in aerosols over Nagoya, Japan, during summer. We analyzed the correlations between the number concentrations of particles in specific hygroscopic growth factor (g) ranges and the mass concentrations of chemical components. This analysis suggests the association of nearly hydrophobic particles with hydrocarbon-like organic aerosol, elemental carbon and semivolatile oxygenated organic aerosol (SV-OOA), that of less hygroscopic particles with SV-OOA and nitrate and that of more hygroscopic particles with low-volatile oxygenated organic aerosol (LV-OOA) and sulfate. The hygroscopicity parameter (κ) of organics was derived based on the g distributions and chemical composition of 150 nm particles. The κ of the organics correlated positively with the fraction of the total organic mass spectral signal at m/z 44 and the volume fraction of the LV-OOA to the organics, indicating that organics with highly oxygenated structures including carboxylic acid groups contribute to the water uptake. The number-size distributions of the nearly hydrophobic particles with g around 1.0 and 1.1 correlated with the mass concentrations of chemical components. The results show that the chemical composition of the particles with g around 1.0 was different between the Aitken mode and the accumulation mode size ranges. An analysis for a parameter Fmax of the curves fitted to the CCN efficiency spectra of the particles with g around 1.0 suggests that the coating by organics associated with SV-OOA elevated the CCN activity of these particles.

  4. Chemical characterization of atmospheric particles and source apportionment in the vicinity of a steelmaking industry

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, S.M., E-mail: smarta@ctn.ist.utl.pt [Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10, 139.7 km, 2695-066 Bobadela LRS (Portugal); Lage, J. [Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10, 139.7 km, 2695-066 Bobadela LRS (Portugal); Fernández, B. [Global R& D, ArcelorMittal, Avilés (Spain); Garcia, S. [Instituto de Soldadura e Qualidade, Av. Prof. Dr. Cavaco Silva, 33, 2740-120 Porto Salvo (Portugal); Reis, M.A.; Chaves, P.C. [Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10, 139.7 km, 2695-066 Bobadela LRS (Portugal)

    2015-07-15

    The objective of this work was to provide a chemical characterization of atmospheric particles collected in the vicinity of a steelmaking industry and to identify the sources that affect PM{sub 10} levels. A total of 94 PM samples were collected in two sampling campaigns that occurred in February and June/July of 2011. PM{sub 2.5} and PM{sub 2.5–10} were analyzed for a total of 22 elements by Instrumental Neutron Activation Analysis and Particle Induced X-ray Emission. The concentrations of water soluble ions in PM{sub 10} were measured by Ion Chromatography and Indophenol-Blue Spectrophotometry. Positive Matrix Factorization receptor model was used to identify sources of particulate matter and to determine their mass contribution to PM{sub 10}. Seven main groups of sources were identified: marine aerosol identified by Na and Cl (22%), steelmaking and sinter plant represented by As, Cr, Cu, Fe, Ni, Mn, Pb, Sb and Zn (11%), sinter plant stack identified by NH{sub 4}{sup +}, K and Pb (12%), an unidentified Br source (1.8%), secondary aerosol from coke making and blast furnace (19%), fugitive emissions from the handling of raw material, sinter plant and vehicles dust resuspension identified by Al, Ca, La, Si, Ti and V (14%) and sinter plant and blast furnace associated essentially with Fe and Mn (21%). - Highlights: • Emissions from steelworks are very complex. • The larger steelworks contribution to PM{sub 10} was from blast furnace and sinter plant. • Sinter plant stack emissions contributed for 12% of the PM{sub 10} mass. • Secondary aerosol from coke making and blast furnace contributed for 19% of the PM{sub 10}. • Fugitive dust emissions highly contribute to PM{sub 10} mass.

  5. Influence of Ionization Degrees on the Evolutions of Charged Particles in Atmospheric Plasma at Low Altitude

    Institute of Scientific and Technical Information of China (English)

    PANG Xuexia; DENG Zechao; JIA Pengying; LIANG Weihua; LI Xia

    2012-01-01

    A zero-dimensional model which includes 56 species of reactants and 427 reactions is used to study the behavior of charged particles in atmospheric plasmas with different ionization degrees at low altitude (near 0 km). The constant coefficient nonlinear equations are solved by using the Quasi-steady-state approximation method. The electron lifetimes are obtained for afterglow plasma with different initial values, and the temporal evolutions of the main charged species are presented, which are dominant in reaction processes. The results show that the electron number density decays quickly. The lifetimes of electrons are shortened by about two orders with increasing ionization degree. Electrons then attach to neutral particles and produce negative ions. When the initial electron densities are in the range of 10l~ ~ 1014 cm-3, the negative ions have sufficiently high densities and long lifetimes for air purification, disinfection and sterilization. Electrons, O(2,-), O(4,-) CO(4,-) and CO(3,-) are the dominant negative species when the initial electron density neo ≤ 1013 cm^(-3), and only electrons and CO3 are left when neo 〉 1015 cm^(-3). N(+,2), N+ and O(+,2) are dominant in the positive charges for any ionization degree. Other positive species, such as 0(+,4), N(+,3), NO(+,2), NO(+,2), Ar(+,2) and H3O+. H2O, are dominant only for a certain ionization degree and in a certain period.

  6. PREPARATION OF Co50Ni50 ULTRAFINES BY CO-REDUCTION OF SOLUTION IN PRESENCE OF POLYMER

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The reduction reaction of aqueous Co2+ -hydrazine, which cannot be conducted under the common condition, is carried out by using both of low-temperature heating and stirring. Metallic ultrafines are prepared by this method. In the presence of polyvinyl alcohol (PVA), it is absorbed on the surface of particles of the product and forms a structure of complex particle, which is favorable to the stability of the powder size distribution. Co50Ni50 magnetic alloy ultrafines with fcc-cubic system can also be prepared from Co2+ -Ni2 +hybrid solution by the same method in the presence of PVA. The effect of PVA amount on the particle size and the stability of Co50Ni50 alloy ultrafines are emphatically discussed.

  7. Atmospheric aging of dust ice nucleating particles - a combined laboratory and field approach

    Science.gov (United States)

    Boose, Yvonne; Rodríguez, Sergio; García, M. Isabel; Linke, Claudia; Schnaiter, Martin; Zipori, Assaf; Crawford, Ian; Lohmann, Ulrike; Kanji, Zamin A.; Sierau, Berko

    2016-04-01

    We present INP data measured in-situ at two mostly free tropospheric locations: the High Altitude Research Station Jungfraujoch (JFJ) in the Swiss Alps, located at 3580 m above sea level (asl) and the Izaña observatory on Tenerife, off the West African shore (2373 m asl). INP concentrations were measured online with the Portable Ice Nucleation Chamber, PINC, at the Jungfraujoch in the winters of 2012, 2013 and 2014 and at Izaña in the summers of 2013 and 2014. Each measurement period lasted between 2 to 6 weeks. During summer, Izaña is frequently within the Saharan Air Layer and thus often exposed to Saharan dust events. Saharan dust also reaches the Jungfraujoch mainly during spring. For offline ice nucleation analysis in the laboratory under similar thermodynamic conditions, airborne dust was collected a) at Izaña with a cyclone directly from the air and b) collected from the surface of the Aletsch glacier close to the JFJ after deposition. Supporting measurements of aerosol particle size distributions and fluorescence were conducted at both locations, as well as cloud water isotope analysis at the Jungfraujoch and aerosol chemistry at Izaña. For both locations the origin of the INPs was investigated with a focus on dust and biological particles using back trajectories and chemical signature. Results show that dust aerosol is the dominant INP type at both locations at a temperature of 241 K. In addition to Saharan dust, also more local, basaltic dust is found at the Jungfraujoch. Biological particles are not observed to play a role for ice nucleation in clouds during winter at Jungfraujoch but are enriched in INP compared to the total aerosol at Izaña also during dust events. The comparison of the laboratory and the field measurements at Izaña indicates a good reproducibility of the field data by the collected dust samples. Field and laboratory data of the dust samples from both locations show that the dust arriving at JFJ is less ice nucleation active

  8. Middle atmosphere response to the solar cycle in irradiance and ionizing particle precipitation

    Directory of Open Access Journals (Sweden)

    K. Semeniuk

    2010-10-01

    Full Text Available The impact of NOx and HOx production by three types of energetic particle precipitation (EPP, aurora, solar proton events and galactic cosmic rays is examined using a chemistry climate model. Ensemble simulations forced by transient EPP derived from observations with one-year repeating sea surface temperatures and fixed chemical boundary conditions were conducted for cases with and without solar cycle in irradiance. Our model results show a wintertime polar stratosphere ozone reduction of between 3 and 10% in agreement with previous studies. EPP is found to modulate the radiative solar cycle effect in the middle atmosphere in a significant way, bringing temperature and ozone variations closer to observed patterns. The Southern Hemisphere polar vortex undergoes an intensification from solar minimum to solar maximum instead of a weakening. This changes the solar cycle variation of the Brewer-Dobson circulation, with a weakening during solar maxima compared to solar minima. In response, the tropical tropopause temperature manifests a statistically significant solar cycle variation resulting in about 4% more water vapour transported into the lower tropical stratosphere during solar maxima compared to solar minima. This has implications for surface temperature variation due to the associated change in radiative forcing.

  9. Heterogeneous Combustion Particles with Distinctive Light-Absorbing and Light-Scattering Phases as Mimics of Internally-Mixed Ambient Atmospheric Particles

    Science.gov (United States)

    Conny, J. M.; Ma, X.; Gunn, L. R.

    2011-12-01

    Particles with heterogeneously-distributed light-absorbing and light-scattering phases were generated from incomplete combustion or thermal decomposition to mimic real atmospheric particles with distinctive optical properties. Individual particles and particle populations were characterized microscopically. The purpose was to examine how optical property measurements of internally-mixed ambient air particles might vary based on the properties of laboratory-generated particles produced under controlled conditions. The project is an initial stage in producing reference samples for calibrating instrumentation for monitoring climatically-important atmospheric aerosols. Binary-phase particles containing black carbon (BC) and a metal or a metal oxide phase were generated from the thermal decomposition or partial combustion of liquid fuels at a variety of temperatures from 600 °C to 1100 °C. Fuels included mixtures of toluene or isooctane and iron pentacarbonyl or titanium tetrachloride. Scanning electron microscopy with energy-dispersive x-ray spectroscopy revealed that burning the fuels at different temperatures resulted in distinctive differences in morphology and carbon vs. metal/metal oxide composition. Particles from toluene/Fe(CO)5 thermal decomposition exhibited aggregated morphologies that were classified as dendritic, soot-like, globular, or composited (dendritic-globular). Particles from isooctane/TiCl4 combustion were typically spherical with surface adducts or aggregates. Diameters of the BC/TiO2 particles averaged 0.68 μm to 0.70 μm. Regardless of combustion temperature, the most abundant particles in each BC/TiO2 sample had an aspect ratio of 1.2. However, for the 600 °C and 900 °C samples the distribution of aspect ratios was skewed toward much larger ratios suggesting significant chainlike aggregation. Carbon and titanium compositions (wt.) for the 600 °C sample were 12 % and 53 %, respectively. In contrast, the composition trended in the opposite

  10. Photons and particles emitted from cold atmospheric-pressure plasma inactivate bacteria and biomolecules independently and synergistically.

    Science.gov (United States)

    Lackmann, Jan-Wilm; Schneider, Simon; Edengeiser, Eugen; Jarzina, Fabian; Brinckmann, Steffen; Steinborn, Elena; Havenith, Martina; Benedikt, Jan; Bandow, Julia E

    2013-12-06

    Cold atmospheric-pressure plasmas are currently in use in medicine as surgical tools and are being evaluated for new applications, including wound treatment and cosmetic care. The disinfecting properties of plasmas are of particular interest, given the threat of antibiotic resistance to modern medicine. Plasma effluents comprise (V)UV photons and various reactive particles, such as accelerated ions and radicals, that modify biomolecules; however, a full understanding of the molecular mechanisms that underlie plasma-based disinfection has been lacking. Here, we investigate the antibacterial mechanisms of plasma, including the separate, additive and synergistic effects of plasma-generated (V)UV photons and particles at the cellular and molecular levels. Using scanning electron microscopy, we show that plasma-emitted particles cause physical damage to the cell envelope, whereas UV radiation does not. The lethal effects of the plasma effluent exceed the zone of physical damage. We demonstrate that both plasma-generated particles and (V)UV photons modify DNA nucleobases. The particles also induce breaks in the DNA backbone. The plasma effluent, and particularly the plasma-generated particles, also rapidly inactivate proteins in the cellular milieu. Thus, in addition to physical damage to the cellular envelope, modifications to DNA and proteins contribute to the bactericidal properties of cold atmospheric-pressure plasma.

  11. Stabilization of ultrafine metal nanocatalysts on thin carbon sheets

    Science.gov (United States)

    Liu, Xiaofang; Cui, Xinrui; Liu, Yiding; Yin, Yadong

    2015-10-01

    A novel strategy was proposed to anchor ultrafine metal nanoparticles (NPs) on thin carbon sheets for highly stable and efficient heterogeneous catalysts. In this facile approach, a dense monolayer of ultrafine AuNPs was sandwiched between a silica core and a resin shell, followed by carbonization of the shell at a high temperature and then selective removal of the silica core. The shrinkage of the shells during carbonization facilitates partial embedment of the AuNPs on the carbon shell surface and provides superior stability against particle sintering during high temperature/mechanical post-treatments and catalytic reactions. It was also found that diffusion of reactants to the surface of AuNPs could be maximized by reducing the thickness of the hollow shells or simply by cracking the shells into thin carbon sheets, both significantly benefiting the catalytic efficiency. The advantages of this ultra-stable architecture together with the densely dispersed catalytic sites were demonstrated by their high stability and superior catalytic activity in reducing hydrophilic 4-nitrophenol and hydrophobic nitrobenzene.A novel strategy was proposed to anchor ultrafine metal nanoparticles (NPs) on thin carbon sheets for highly stable and efficient heterogeneous catalysts. In this facile approach, a dense monolayer of ultrafine AuNPs was sandwiched between a silica core and a resin shell, followed by carbonization of the shell at a high temperature and then selective removal of the silica core. The shrinkage of the shells during carbonization facilitates partial embedment of the AuNPs on the carbon shell surface and provides superior stability against particle sintering during high temperature/mechanical post-treatments and catalytic reactions. It was also found that diffusion of reactants to the surface of AuNPs could be maximized by reducing the thickness of the hollow shells or simply by cracking the shells into thin carbon sheets, both significantly benefiting the

  12. Direct evidence for coastal iodine particles from Laminaria macroalgae – linkage to emissions of molecular iodine

    Directory of Open Access Journals (Sweden)

    D. Wevill

    2004-02-01

    Full Text Available Renewal of ultrafine aerosols in the marine boundary layer may lead to repopulation of the marine distribution and ultimately determine the concentration of cloud condensation nuclei (CCN. Thus the formation of nanometre-scale particles can lead to enhanced scattering of incoming radiation and a net cooling of the atmosphere. The recent demonstration of the chamber formation of new particles from the photolytic production of condensable iodine-containing compounds from diiodomethane (CH2I2, (O'Dowd et al., 2002; Kolb, 2002; Jimenez et al., 2003a; Burkholder and Ravishankara, 2003, provides an additional mechanism to the gas-to-particle conversion of sulphuric acid formed in the photo-oxidation of dimethylsulphide for marine aerosol repopulation. CH2I2 is emitted from seaweeds (Carpenter et al., 1999, 2000 and has been suggested as an initiator of particle formation. We demonstrate here for the first time that ultrafine iodine-containing particles are produced by intertidal macroalgae exposed to ambient levels of ozone. The particle composition is very similar both to those formed in the chamber photo-oxidation of diiodomethane and in the oxidation of molecular iodine by ozone. The particles formed in all three systems are similarly aspherical and behave alike when exposed to increased humidity environments. Direct coastal boundary layer observations of molecular iodine, ultrafine particle production and iodocarbons are reported. Using a newly measured molecular iodine photolysis rate, it is shown that, if atomic iodine is involved in the observed particle bursts, it is of the order of at least 1000 times more likely to result from molecular iodine photolysis than diiodomethane photolysis. A hypothesis for molecular iodine release from intertidal macroalgae is presented and the potential importance of macroalgal iodine particles in their contribution to CCN and global radiative forcing are discussed.

  13. Interactions of mineral dust with pollution and clouds: An individual-particle TEM study of atmospheric aerosol from Saudi Arabia

    Science.gov (United States)

    Pósfai, Mihály; Axisa, Duncan; Tompa, Éva; Freney, Evelyn; Bruintjes, Roelof; Buseck, Peter R.

    2013-03-01

    Aerosol particles from desert dust interact with clouds and influence climate on regional and global scales. The Riyadh (Saudi Arabia) aerosol campaign was initiated to study the effects of dust particles on cloud droplet nucleation and cloud properties. Here we report the results of individual-particle studies of samples that were collected from an aircraft in April 2007. We used analytical transmission electron microscopy, including energy-dispersive X-ray spectrometry, electron diffraction, and imaging techniques for the morphological, chemical, and structural characterization of the particles. Dust storms and regional background conditions were encountered during four days of sampling. Under dusty conditions, the coarse (supermicrometer) fraction resembles freshly crushed rock. The particles are almost exclusively mineral dust grains and include common rock-forming minerals, among which clay minerals, particularly smectites, are most abundant. Unaltered calcite grains also occur, indicating no significant atmospheric processing. The particles have no visible coatings but some contain traces of sulfur. The fine (submicrometer) fraction is dominated by particles of anthropogenic origin, primarily ammonium sulfate (with variable organic coating and some with soot inclusions) and combustion-derived particles (mostly soot). In addition, submicrometer, iron-bearing clay particles also occur, many of which are internally mixed with ammonium sulfate, soot, or both. We studied the relationships between the properties of the aerosol and the droplet microphysics of cumulus clouds that formed above the aerosol layer. Under dusty conditions, when a large concentration of coarse-fraction mineral particles was in the aerosol, cloud drop concentrations were lower and droplet diameters larger than under regional background conditions, when the aerosol was dominated by submicrometer sulfate particles.

  14. Air Quality Impacts of Atmospheric Particles & Trace Gases: Field Studies in Diverse Environments

    Science.gov (United States)

    Mwaniki, George R.

    Air pollution impacts occur at all scales, meaning that policies and air quality management practices must be implemented and coordinated at the local, regional, national, and global scales. This dissertation is part of a continuing effort to improve our understanding of various air quality related issues in different environments. The dissertation consists of four studies. In the first study, wintertime chemical composition of water-soluble particulate matter with aerodynamic diameter less than 2.5 microm (PM2.5) was monitored in the Treasure Valley region near Boise, Idaho. This study was aimed at understanding the major drivers of wintertime PM2.5 within the locality of Boise and its suburbs. From this study, organics and particulate nitrate were the dominant contributors to the PM2.5 mass during wintertime. In the second study, particle size distribution, light scattering coefficient, speciated water soluble PM2.5, and cloud condensation nuclei (CCN) concentration were monitored in a mixed deciduous forest in Northern Michigan during the Community Atmosphere-Biosphere Interactions Experiment (CABINEX-2009). The overall goal of this study was to understand on how emissions of biogenic volatile organic compounds (BVOC) affect the gas-phase and particle-phase chemistry in the near-canopy environment, and the implications on local and regional air quality. From this study aerosol derived from the oxidation of BVOCs exhibited reduced hygroscopicity and CCN activation potential compared to aerosols derived from anthropogenic activities. The third study employed the eddy covariance (EC) technique to understand source-sink interactions of carbon dioxide (CO2), methane (CH 4), carbon monoxide (CO) and nitrous oxide (N2O) in Xi'an, China. In this study urban vegetation were found to play a major role in regulating CO2 emissions within the city while vehicular activities were a major driver for CO and CH4 fluxes. In the fourth study, visibility degradation effects of

  15. Correlations between urban atmospheric light extinction coefficients and fine particle mass concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Trier, A.; Cabrini, N.; Ferrer, J. [Facultad de Ciencia, Universidad de Santiago de Chile, Santiago 2 (Chile); Olaeta, I. [SESMA, Santiago 1 (Chile)

    1997-07-01

    Total horizontal atmospheric light extinction coefficients as well as particle mass concentrations have been measured in downtown areas of Santiago de Chile, a heavily polluted city. Measurement campaigns were carried out in 1994 in 1995. Extinction measurements were made by a telephotometric technique in four wavelength bands; oscillating mass balance type instruments were used to measure PM2.5 and PM10 mass concentrations. The latter type instrument had not been available heretofore. The extensive continuous PM2.5 measurements are the first for this city. Strong and highly significant statistical correlations were found between extinction coefficients and mass concentrations, especially with the fine respirable or PM2.5 mass concentrations. Angstrom exponents and, in one case, mass extinction coefficients have been estimated. [Spanish] Se ha medido coeficientes atmosfericos totales horizontales de extincion de luz asi como concentraciones de masa de particulas atmosfericas en zonas centricas de Santiago de Chile, una ciudad altamente contaminada. Las campanas de medicion se han hecho en 1994 y en 1995. Las mediciones de extincion se han hecho por un metodo telefotometrico en cuatro bandas espectrales; las concentraciones de masa PM2.5 y PM10 se han medido con instrumentos del tipo de balanzas de masa oscilantes. Tales instrumentos no han estado disponibles durante trabajos anteriores. Las extensas mediciones continuas de concentraciones de masa PM2.5 son las primeras para Santiago de Chile. Se han encontrado fuertes correlaciones estadisticas, altamente significativas, entre coeficientes de extincion y concentraciones de masa, especialmente las concentraciones de particulas finas respirables PM2.5. Se han estimado tambien exponentes de Angstrom y, en un caso, coeficientes masicos de extincion.

  16. A method for detecting the presence of organic fraction in nucleation mode sized particles

    Directory of Open Access Journals (Sweden)

    P. Vaattovaara

    2005-06-01

    Full Text Available New particle formation and growth has a very important role in many climate processes. However, the overall knowlegde of the chemical composition of atmospheric nucleation mode (particle diameter, d<20 nm and the lower end of Aitken mode particles (d≤50 nm is still insufficient. In this work, we have applied the UFO-TDMA (ultrafine organic tandem differential mobility analyzer method to shed light on the presence of organic fraction in the nucleation mode size class in different atmospheric environments. The basic principle of the organic fraction detection is based on our laboratory UFO-TDMA measurements with organic and inorganic compounds. Our laboratory measurements indicate that the usefulness of the UFO-TDMA in the field experiments would arise especially from the fact that atmospherically the most relevant inorganic compounds do not grow in subsaturated ethanol vapor, when particle size is 10nm in diameter and saturation ratio is about 86% or below it. Furthermore, internally mixed particles composed of ammonium bisulfate and sulfuric acid with sulfuric acid mass fraction ≤33% show no growth at 85% saturation ratio. In contrast, 10 nm particles composed of various organic compounds of atmospheric relevance are able to grow in those conditions. These discoveries indicate that it is possible to detect the presence of organics in atmospheric nucleation mode sized particles using the UFO-TDMA method. In the future, the UFO-TDMA is expected to be an important aid to describe the composition of atmospheric newly-formed particles.

  17. A method for detecting the presence of organic fraction in nucleation mode sized particles

    Directory of Open Access Journals (Sweden)

    P. Vaattovaara

    2005-01-01

    Full Text Available New particle formation and growth has a very important role in many climate processes. However, the overall knowlegde of the chemical composition of atmospheric nucleation mode (particle diameter, d<20 nm and the lower end of Aitken mode particles (d≤50 nm is still insufficient. In this work, we have applied the UFO-TDMA (ultrafine organic tandem differential mobility analyzer method to shed light on the presence of an organic fraction in the nucleation mode size class in different atmospheric environments. The basic principle of the organic fraction detection is based on our laboratory UFO-TDMA measurements with organic and inorganic compounds. Our laboratory measurements indicate that the usefulness of the UFO-TDMA in the field experiments would arise especially from the fact that atmospherically the most relevant inorganic compounds do not grow in subsaturated ethanol vapor, when particle size is 10 nm in diameter and saturation ratio is about 86% or below it. Furthermore, internally mixed particles composed of ammonium bisulfate and sulfuric acid with sulfuric acid mass fraction ≤33% show no growth at 85% saturation ratio. In contrast, 10 nm particles composed of various oxidized organic compounds of atmospheric relevance are able to grow in those conditions. These discoveries