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Sample records for aerosol particle growth

  1. Size matters in the water uptake and hygroscopic growth of atmospherically relevant multicomponent aerosol particles.

    PubMed

    Laskina, Olga; Morris, Holly S; Grandquist, Joshua R; Qin, Zhen; Stone, Elizabeth A; Tivanski, Alexei V; Grassian, Vicki H

    2015-05-14

    Understanding the interactions of water with atmospheric aerosols is crucial for determining the size, physical state, reactivity, and climate impacts of this important component of the Earth's atmosphere. Here we show that water uptake and hygroscopic growth of multicomponent, atmospherically relevant particles can be size dependent when comparing 100 nm versus ca. 6 μm sized particles. It was determined that particles composed of ammonium sulfate with succinic acid and of a mixture of chlorides typical of the marine environment show size-dependent hygroscopic behavior. Microscopic analysis of the distribution of components within the aerosol particles show that the size dependence is due to differences in the mixing state, that is, whether particles are homogeneously mixed or phase separated, for different sized particles. This morphology-dependent hygroscopicity has consequences for heterogeneous atmospheric chemistry as well as aerosol interactions with electromagnetic radiation and clouds.

  2. Formation and growth of indoor air aerosol particles as a result of D-limonene oxidation

    NASA Astrophysics Data System (ADS)

    Vartiainen, E.; Kulmala, M.; Ruuskanen, T. M.; Taipale, R.; Rinne, J.; Vehkamäki, H.

    Oxidation of D-limonene, which is a common monoterpene, can lead to new aerosol particle formation in indoor environments. Thus, products containing D-limonene, such as citrus fruits, air refresheners, household cleaning agents, and waxes, can act as indoor air aerosol particle sources. We released D-limonene into the room air by peeling oranges and measured the concentration of aerosol particles of three different size ranges. In addition, we measured the concentration of D-limonene, the oxidant, and the concentration of ozone, the oxidizing gas. Based on the measurements we calculated the growth rate of the small aerosol particles, which were 3-10 nm in diameter, to be about 6300nmh-1, and the losses of the aerosol particles that were due to the coagulation and condensation processes. From these, we further approximated the concentration of the condensable vapour and its source rate and then calculated the formation rate of the small aerosol particles. For the final result, we calculated the nucleation rate and the maximum number of molecules in a critical cluster. The nucleation rate was in the order of 105cm-3s-1 and the number of molecules in a critical-sized cluster became 1.2. The results were in agreement with the activation theory.

  3. Hygroscopic growth of urban aerosol particles during the 2009 Mirage-Shanghai Campaign

    NASA Astrophysics Data System (ADS)

    Ye, Xingnan; Tang, Chen; Yin, Zi; Chen, Jianmin; Ma, Zhen; Kong, Lingdong; Yang, Xin; Gao, Wei; Geng, Fuhai

    2013-01-01

    The hygroscopic properties of submicrometer urban aerosol particles were studied during the 2009 Mirage-Shanghai Campaign. The urban aerosols were composed of more-hygroscopic and nearly-hydrophobic particles, together with a trace of less-hygroscopic particles. The mean hygroscopicity parameter κ of the more-hygroscopic mode varied in the range of 0.27-0.39 depending on particle size. The relative abundance of the more-hygroscopic particles at any size was ca. 70%, slightly increasing with particle size. The number fraction of the nearly-hydrophobic particles fluctuated between 0.1 and 0.4 daily, in accordance with traffic emissions and atmospheric diffusion. The results from relative humidity dependence on hygroscopic growth and chemical analysis of fine particles indicated that particulate nitrate formation through the homogenous gas-phase reaction was suppressed under ammonia-deficient atmosphere in summer whereas the equilibrium was broken by more available NH3 during adverse meteorological conditions.

  4. Early growth dynamical implications for the steerability of stratospheric solar radiation management via sulfur aerosol particles

    NASA Astrophysics Data System (ADS)

    Benduhn, François; Schallock, Jennifer; Lawrence, Mark G.

    2016-09-01

    Aerosol growth dynamics may have implications for the steerability of stratospheric solar radiation management via sulfur particles. This paper derives a set of critical initial growth conditions that are analyzed as a function of two key parameters: the initial concentration of the injected sulfuric acid and its dilution rate with the surrounding air. Based upon this analysis, early aerosol growth dynamical regimes may be defined and classified in terms of their likelihood to serve as candidates for the controlled generation of a radiatively effective aerosol. Our results indicate that the regime that fulfills all critical conditions would require that airplane turbines be used to provide sufficient turbulence. The regime's parameter space is narrow and related to steep gradients, thus pointing to potential fine tuning requirements. More research, development, and testing would be required to refine our findings and determine their global-scale implications.

  5. Determination of particle nucleation and growth rates from measured aerosol size distributions

    NASA Astrophysics Data System (ADS)

    Verheggen, B.; Mozurkewich, M.

    2003-04-01

    The effects of aerosols on atmospheric chemistry, health and climate are dependent on particle size and composition, and therefore on particle nucleation and growth. An analytical model has been developed to determine nucleation and growth rates from measurements of consecutive aerosol size distributions. The evolution of an aerosol population in time is described by the General Dynamic Equation (GDE). Wall loss, coagulation loss and coagulation production are determined, based on the measured aerosol size distributions. Taking their contributions into account, a non-linear regression analysis of the GDE is performed for each time interval to find the value of the growth rate, that gives best agreement between the measured and calculated change in the size distribution. Other parameters can also be verified and/or optimized by regression analysis. Knowing the growth rate as a function of time (and size) from the regression analysis, each measured cohort of particles is tracked backwards in time to their time of formation, where the radius of the critical cluster is assumed to be 0.5 nm. The number density of each cohort has decreased since their formation, due to wall losses and coagulation processes. Perturbation theory is used to approximate the contribution of within mode coagulation in decreasing the number density. Wall losses and coagulation scavenging are well characterized for each time interval. The integrated losses, from time of formation to time of measurement, are used to obtain the number of nucleated particles, and ultimately the -empirically determined- nucleation rate. The analysis is applied to measurements made in Calspan's 590 m3 smog chamber, following SO2 nucleation.

  6. Particle growth by acid-catalyzed heterogeneous reactions of organic carbonyls on preexisting aerosols.

    PubMed

    Jang, Myoseon; Carroll, Brian; Chandramouli, Bharadwaj; Kamens, Richard M

    2003-09-01

    Aerosol growth by the heterogeneous reactions of different aliphatic and alpha,beta-unsaturated carbonyls in the presence/absence of acidified seed aerosols was studied in a 2 m long flow reactor (2.5 cm i.d.) and a 0.5-m3 Teflon film bag under darkness. For the flow reactor experiments, 2,4-hexadienal, 5-methyl-3-hexen-2-one, 2-cyclohexenone, 3-methyl-2-cyclopentenone, 3-methyl-2-cyclohexenone, and octanal were studied. The carbonyls were selected based on their reactivity for acid-catalyzed reactions, their proton affinity, and their similarity to the ring-opening products from the atmospheric oxidation of aromatics. To facilitate acid-catalyzed heterogeneous hemiacetal/acetal formation, glycerol was injected along with inorganic seed aerosols into the flow reactor system. Carbonyl heterogeneous reactions were accelerated in the presence of acid catalysts (H2SO4), leading to higher aerosol yields than in their absence. Aldehydes were more reactive than ketones for acid-catalyzed reactions. The conjugated functionality also resulted in higher organic aerosol yieldsthan saturated aliphatic carbonyls because conjugation with the olefinic bond increases the basicity of the carbonyl leading to increased stability of the protonated carbonyl. Aerosol population was measured from a series of sampling ports along the length of the flow reactor using a scanning mobility particle sizer. Fourier transform infrared spectrometry of either an impacted liquid aerosol layer or direct reaction of carbonyls as a thin liquid layer on a zinc selenide FTIR disk was employed to demonstrate the direct transformation of chemical functional groups via the acid-catalyzed reactions. These results strongly indicate that atmospheric multifunctional organic carbonyls, which are created by atmospheric photooxidation reactions, can contribute significantly to secondary organic aerosol formation through acid-catalyzed heterogeneous reactions. Exploratory studies in 25- and 190-m3 outdoor chambers

  7. Measurement, growth types and shrinkage of newly formed aerosol particles at an urban research platform

    NASA Astrophysics Data System (ADS)

    Salma, Imre; Németh, Zoltán; Weidinger, Tamás; Kovács, Boldizsár; Kristóf, Gergely

    2016-06-01

    Budapest platform for Aerosol Research and Training (BpART) was created for advancing long-term on-line atmospheric measurements and intensive aerosol sample collection campaigns in Budapest. A joint study including atmospheric chemistry or physics, meteorology, and fluid dynamics on several-year-long data sets obtained at the platform confirmed that the location represents a well-mixed, average atmospheric environment for the city centre. The air streamlines indicated that the host and neighbouring buildings together with the natural orography play an important role in the near-field dispersion processes. Details and features of the airflow structure were derived, and they can be readily utilised for further interpretations. An experimental method to determine particle diffusion losses in the differential mobility particle sizer (DMPS) system of the BpART facility was proposed. It is based on CPC-CPC (condensation particle counter) and DMPS-CPC comparisons. Growth types of nucleated particles observed in 4 years of measurements were presented and discussed specifically for cities. Arch-shaped size distribution surface plots consisting of a growth phase followed by a shrinkage phase were characterised separately since they supply information on nucleated particles. They were observed in 4.5 % of quantifiable nucleation events. The shrinkage phase took 1 h 34 min in general, and the mean shrinkage rate with standard deviation was -3.8 ± 1.0 nm h-1. The shrinkage of particles was mostly linked to changes in local atmospheric conditions, especially in global radiation and the gas-phase H2SO4 concentration through its proxy, or to atmospheric mixing in few cases. Some indirect results indicate that variations in the formation and growth rates of nucleated particles during their atmospheric transport could be a driving force of shrinkage for particles of very small sizes and on specific occasions.

  8. Aerosol-CFD modelling of ultrafine and black carbon particle emission, dilution, and growth near roadways

    NASA Astrophysics Data System (ADS)

    Huang, L.; Gong, S. L.; Gordon, M.; Liggio, J.; Staebler, R. M.; Stroud, C. A.; Lu, G.; Mihele, C.; Brook, J. R.; Jia, C. Q.

    2014-05-01

    Many studies have shown that on-road vehicle emissions are the dominant source of ultrafine particles (UFP; diameter < 100 nm) in urban areas and near-roadway environments. In order to advance our knowledge on the complex interactions and competition among atmospheric dilution, dispersion and dynamics of UFPs, an aerosol dynamics-CFD coupled model is developed and validated against field measurements. A unique approach of applying periodic boundary conditions is proposed to model pollutant dispersion and dynamics in one unified domain from the tailpipe level to the ambient near-road environment. This approach significantly reduces the size of the computational domain, and therefore, allows fast simulation of multiple scenarios. The model is validated against measured turbulent kinetic energy (TKE) and pollution gradients near a major highway. Through a model sensitivity analysis, the relative importance of individual aerosol dynamical processes on the total particle number concentration (N) and particle number-size distribution (PSD) near a highway is investigated. The results demonstrate that (1) coagulation has a negligible effect on N and particle growth, (2) binary homogeneous nucleation (BHN) of H2SO4-H2O is likely responsible for elevated N closest to the road, (3) N and particle growth are very sensitive to the condensation of semi-volatile organics (SVOCs), particle dry deposition, and the interaction between these processes. The results also indicate that, without the proper treatment of atmospheric boundary layer (i.e. its wind profile and turbulence quantities), the nucleation rate would be underestimated by a factor of 5 in the vehicle wake region due to overestimated mixing. Therefore, introducing ABL conditions to activity-based emission models may potentially improve their performance in estimating UFP traffic emissions.

  9. The Remarkable Condensational Growth of Cloud Droplets Grown on Giant Sea-salt Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Jensen, J. B.; Nugent, A. D.

    2015-12-01

    Condensational growth of cloud drops is often assumed to be a well-understood process, using the drop growth equation: After activation of cloud condensation nuclei into cloud drops at cloud base, model studies often assume that drops quickly become dilute and consist of pure water. As a consequence, adiabatic ascent predicts that the growth rate of these drops is inversely proportional to their radius, and consequently that the drop spectrum will narrow with altitude. Here we demonstrate that drop growth on giant sea-salt aerosol particles (GCCN, dry radius > 0.5 μm) behaves very differently. For typical marine stratocumulus updrafts (0.4 m s-1), and for dry radius > 2 μm, these drops typically remain concentrated solution drops, and their condensational growth is so fast that they accelerate away from the main drop peak, and thus very rapidly attain precipitation drop sizes through condensation only. We show how many studies, that have attempted to include the effects of GCCN by initiating large pure water drops at cloud base, may have seriously underestimated the effects of GCCN on warm rain formation. We also speculate on possible solutions to this issue.

  10. On the growth of nitric and sulfuric acid aerosol particles under stratospheric conditions

    NASA Technical Reports Server (NTRS)

    Hamill, Patrick; Turco, R. P.; Toon, O. B.

    1988-01-01

    A theory for the formation of frozen aerosol particles in the Antarctic stratosphere was developed and applied to the formation of polar stratospheric clouds. The theory suggests that the condensed ice particles are composed primarily of nitric acid and water, with small admixtures of sulfuric and hydrochloric acids in solid solution. The proposed particle formation mechanism is in agreement with the magnitude and seasonal behavior of the optical extinction observed in the winter polar stratosphere.

  11. Hygroscopic growth of urban aerosol particles in Beijing (China) during wintertime: a comparison of three experimental methods

    NASA Astrophysics Data System (ADS)

    Meier, J.; Wehner, B.; Massling, A.; Birmili, W.; Nowak, A.; Gnauk, T.; Brüggemann, E.; Herrmann, H.; Min, H.; Wiedensohler, A.

    2009-09-01

    The hygroscopic properties of atmospheric aerosols are highly relevant for the quantification of radiative effects in the atmosphere, but also of interest for the assessment of particle health effects upon inhalation. This article reports measurements of aerosol particle hygroscopicity in the highly polluted urban atmosphere of Beijing, China in January 2005. The meteorological conditions corresponded to a relatively cold and dry atmosphere. Three different methods were used: 1) A combination of Humidifying Differential Mobility Particle Sizer (H-DMPS) and Twin Differential Mobility Particle Sizer (TDMPS) measurements, 2) A Hygroscopic Tandem Differential Mobility Analyzer (H-TDMA), and 3) A simplistic solubility model fed by chemical particle composition determined from Micro Orifice Uniform Deposit Impactor (MOUDI) samples. From the H-DMPS and TDMPS particle number size distributions, a size-resolved descriptive hygroscopic growth factor (DHGF) was determined for the relative humidities (RH) 55%, 77% and 90%, and particle diameters between 30 and 400 nm. In Beijing, the highest DHGFs were observed for accumulation mode particles, 1.40 (±0.03) at 90% RH. DHGF decreased significantly with particle size, reaching 1.04 (±0.15) at 30 nm. H-TDMA data also suggest a decrease in growth factor towards the biggest particles investigated (350 nm), associated with an increasing fraction of nearly hydrophobic particles. The agreement between the H-DMPS/TDMPS and H-TDMA methods was satisfactory in the accumulation mode size range (100-400 nm). In the Aitken mode range (<100 nm), the H-DMPS/TDMPS method yielded growth factors lower by up to 0.1 at 90% RH. The application of the solubility model based on measured chemical composition clearly reproduced the size-dependent trend in hygroscopic particle growth observed by the other methods. In the case of aerosol dominated by inorganic ions, the composition-derived growth factors tended to agree (± 0.05) or underestimate (up to

  12. Hygroscopic growth of size-resolved, emission-source classified, aerosol particles sampled across the United States

    NASA Astrophysics Data System (ADS)

    Shingler, T.; Crosbie, E. C.; Ziemba, L. D.; Anderson, B. E.; Campuzano Jost, P.; Jimenez, J. L.; Mikoviny, T.; Wisthaler, A.; Sorooshian, A.

    2014-12-01

    The hygroscopic growth of atmospheric aerosol particles is a key air quality parameter, impacting the radiation budget, visibility, and cloud formation. During the DC3 and SEAC4RS field campaigns (>300 total flight hours), measurements were made over 32 US states, Canada, the Pacific Ocean, and the Gulf of Mexico, between the surface and 41,000 feet ASL. The aircraft research payloads included a suite of in-situ aerosol and gas phase instruments. The Differential Aerosol Sizing and Hygroscopicity Spectrometer Probe (DASH-SP) and the Langley Aerosol Research Group Experiment (LARGE) humidified nephelometer instrument applied different techniques to measure water uptake by aerosol particles at prescribed relative humidity values. Size-resolved growth factor (GF ≡ Dp,wet/Dp,dry) measurements by the DASH-SP are compared to bulk scattering measurements (f(RH) ≡ σscat,wet/σscat,dry) by the LARGE instrument. Spatial location and volatile organic compound tracers such as isoprene and acetonitrile are used to classify the origin of distinct air masses, including: forest fires, biogenic-emitting forests, agricultural use lands, marine boundary layer, urban, and rural background. Analyses of GF results by air mass origin are reported and results are compared with f(RH) measurements. A parameterization between the f(RH) and GF measurements and its potential uses are discussed.

  13. Chemical characterization of submicron aerosol and particle growth events at a national background site (3295 m a.s.l.) on the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Du, W.; Sun, Y. L.; Xu, Y. S.; Jiang, Q.; Wang, Q. Q.; Yang, W.; Wang, F.; Bai, Z. P.; Zhao, X. D.; Yang, Y. C.

    2015-09-01

    Atmospheric aerosols exert highly uncertain impacts on radiative forcing and also have detrimental effects on human health. While aerosol particles are widely characterized in megacities in China, aerosol composition, sources and particle growth in rural areas in the Tibetan Plateau remain less understood. Here we present the results from an autumn study that was conducted from 5 September to 15 October 2013 at a national background monitoring station (3295 m a.s.l.) in the Tibetan Plateau. The submicron aerosol composition and particle number size distributions were measured in situ with an Aerodyne Aerosol Chemical Speciation Monitor (ACSM) and a Scanning Mobility Particle Sizer (SMPS). The average mass concentration of submicron aerosol (PM1) is 11.4 μg m-3 (range: 1.0-78.4 μg m-3) for the entire study, which is much lower than observed at urban and rural sites in eastern China. Organics dominated PM1, accounting for 43 % on average, followed by sulfate (28 %) and ammonium (11 %). Positive Matrix Factorization analysis of ACSM organic aerosol (OA) mass spectra identified an oxygenated OA (OOA) and a biomass burning OA (BBOA). The OOA dominated OA composition, accounting for 85 % on average, 17 % of which was inferred from aged BBOA. The BBOA contributed a considerable fraction of OA (15 %) due to the burning of cow dung and straw in September. New particle formation and growth events were frequently observed (80 % of time) throughout the study. The average particle growth rate is 2.0 nm h-1 (range: 0.8-3.2 nm h-1). By linking the evolution of particle number size distribution to aerosol composition, we found an elevated contribution of organics during particle growth periods and also a positive relationship between the growth rate and the fraction of OOA in OA, which potentially indicates an important role of organics in particle growth in the Tibetan Plateau.

  14. Organic Nitrate Contribution to New Particle Formation and Growth in Secondary Organic Aerosols from α-Pinene Ozonolysis.

    PubMed

    Berkemeier, Thomas; Ammann, Markus; Mentel, Thomas F; Pöschl, Ulrich; Shiraiwa, Manabu

    2016-06-21

    The chemical kinetics of organic nitrate production during new particle formation and growth of secondary organic aerosols (SOA) were investigated using the short-lived radioactive tracer (13)N in flow-reactor studies of α-pinene oxidation with ozone. Direct and quantitative measurements of the nitrogen content indicate that organic nitrates accounted for ∼40% of SOA mass during initial particle formation, decreasing to ∼15% upon particle growth to the accumulation-mode size range (>100 nm). Experiments with OH scavengers and kinetic model results suggest that organic peroxy radicals formed by α-pinene reacting with secondary OH from ozonolysis are key intermediates in the organic nitrate formation process. The direct reaction of α-pinene with NO3 was found to be less important for particle-phase organic nitrate formation. The nitrogen content of SOA particles decreased slightly upon increase of relative humidity up to 80%. The experiments show a tight correlation between organic nitrate content and SOA particle-number concentrations, implying that the condensing organic nitrates are among the extremely low volatility organic compounds (ELVOC) that may play an important role in the nucleation and growth of atmospheric nanoparticles. PMID:27219077

  15. Initial steps of aerosol growth

    NASA Astrophysics Data System (ADS)

    Kulmala, M.; Laakso, L.; Lehtinen, K. E. J.; Riipinen, I.; Dal Maso, M.; Anttila, T.; Kerminen, V.-M.; Hõrrak, U.; Vana, M.; Tammet, H.

    2004-12-01

    The formation and growth of atmospheric aerosols depend on several steps, namely nucleation, initial steps of growth and subsequent - mainly condensational - growth. This work focuses on the initial steps of growth, meaning the growth right after nucleation, where the interplay of curvature effects and thermodynamics has a significant role on the growth kinetics. More specifically, we investigate how ion clusters and aerosol particles grow from 1.5 nm to 20 nm (diameter) in atmospheric conditions using experimental data obtained by air ion and aerosol spectrometers. The measurements have been performed at a boreal forest site in Finland. The observed trend that the growth rate seems to increase as a function of size can be used to investigate possible growth mechanisms. Such a growth rate is consistent with a recently suggested nano-Köhler mechanism, in which growth is activated at a certain size with respect to condensation of organic vapors. The results also imply that charge-enhanced growth associated with ion-mediated nucleation plays only a minor role in the initial steps of growth, since it would imply a clear decrease of the growth rate with size. Finally, further evidence was obtained on the earlier suggestion that atmospheric nucleation and the subsequent growth of fresh nuclei are likely to be uncoupled phenomena via different participating vapors.

  16. Initial steps of aerosol growth

    NASA Astrophysics Data System (ADS)

    Kulmala, O.; Laakso, L.; Lehtinen, K. E. J.; Riipinen, I.; Dal Maso, M.; Anttila, T.; Kerminen, V.-M.; Hõrrak, U.; Vana, M.; Tammet, H.

    2004-09-01

    The formation and growth of atmospheric aerosols depend on several steps, namely nucleation, initial steps of growth and subsequent - mainly condensational - growth. This work focuses on the initial steps of growth, meaning the growth right after nucleation, where the interplay of curvature effects and thermodynamics has a significant role on the growth kinetics. More specifically, we investigate how ion clusters and aerosol particles grow from 1.5 nm to 20 nm in atmospheric conditions using experimental data obtained by air ion and aerosol spectrometers. The measurements have been performed at a boreal forest site in Finland. The observed trend that the growth rate seems to increase as a function of size can be used to investigate possible growth mechanisms. Such a growth rate is consistent with a recently suggested nano-Köhler mechanism, in which growth is activated at a certain size with respect to condensation of organic vapors. The results also imply that charge-enhance growth associated with ion-mediated nucleation plays only a minor role in the initial steps of growth, since it would imply a clear decrease of the growth rate with size. Finally, further evidence was obtained on the earlier suggestion that atmospheric nucleation and the subsequent growth of fresh nuclei are likely to be uncoupled phenomena via different participating vapors.

  17. Aerosol-computational fluid dynamics modeling of ultrafine and black carbon particle emission, dilution, and growth near roadways

    NASA Astrophysics Data System (ADS)

    Huang, L.; Gong, S. L.; Gordon, M.; Liggio, J.; Staebler, R.; Stroud, C. A.; Lu, G.; Mihele, C.; Brook, J. R.; Jia, C. Q.

    2014-12-01

    Many studies have shown that on-road vehicle emissions are the dominant source of ultrafine particles (UFPs; diameter < 100 nm) in urban areas and near-roadway environments. In order to advance our knowledge on the complex interactions and competition among atmospheric dilution, dispersion, and dynamics of UFPs, an aerosol dynamics-computational fluid dynamics (CFD) coupled model is developed and validated against field measurements. A unique approach of applying periodic boundary conditions is proposed to model pollutant dispersion and dynamics in one unified domain from the tailpipe level to the ambient near-road environment. This approach significantly reduces the size of the computational domain, and therefore allows fast simulation of multiple scenarios. The model is validated against measured turbulent kinetic energy (TKE) and horizontal gradient of pollution concentrations perpendicular to a major highway. Through a model sensitivity analysis, the relative importance of individual aerosol dynamical processes on the total particle number concentration (N) and particle number-size distribution (PSD) near a highway is investigated. The results demonstrate that (1) coagulation has a negligible effect on N and particle growth, (2) binary homogeneous nucleation (BHN) of H2SO4-H2O is likely responsible for elevated N closest to the road, and (3) N and particle growth are very sensitive to the condensation of semi-volatile organics (SVOCs), particle dry deposition, and the interaction between these processes. The results also indicate that, without the proper treatment of the atmospheric boundary layer (i.e., its wind profile and turbulence quantities), the nucleation rate would be underestimated by a factor of 5 in the vehicle wake region due to overestimated dilution. Therefore, introducing atmospheric boundary layer (ABL) conditions to activity-based emission models may potentially improve their performance in estimating UFP traffic emissions.

  18. Measuring and modeling the hygroscopic growth of two humic substances in mixed aerosol particles of atmospheric relevance

    NASA Astrophysics Data System (ADS)

    Zamora, I. R.; Jacobson, M. Z.

    2013-09-01

    The hygroscopic growth of atmospheric particles affects atmospheric chemistry and Earth's climate. Water-soluble organic carbon (WSOC) constitutes a significant fraction of the dry submicron mass of atmospheric aerosols, thus affecting their water uptake properties. Although the WSOC fraction is comprised of many compounds, a set of model substances can be used to describe its behavior. For this study, mixtures of Nordic aquatic fulvic acid reference (NAFA) and Fluka humic acid (HA), with various combinations of inorganic salts (sodium chloride and ammonium sulfate) and other representative organic compounds (levoglucosan and succinic acid), were studied. We measured the equilibrium water vapor pressure over bulk solutions of these mixtures as a function of temperature and solute concentration. New water activity (aw) parameterizations and hygroscopic growth curves at 25 °C were calculated from these data for particles of equivalent composition. We examined the effect of temperature on the water activity and found a maximum variation of 9% in the 0-30 °C range, and 2% in the 20-30 °C range. Five two-component mixtures were studied to understand the effect of adding a humic substance (HS), such as NAFA and HA, to an inorganic salt or a saccharide. The deliquescence point at 25 °C for HS-inorganic mixtures did not change significantly from that of the pure inorganic species. However, the hygroscopic growth of HA / inorganic mixtures was lower than that exhibited by the pure salt, in proportion to the added mass of HA. The addition of NAFA to a highly soluble solute (ammonium sulfate, sodium chloride or levoglucosan) in water had the same effect as the addition of HA to the inorganic species for most of the water activity range studied. Yet, the water uptake of these NAFA mixtures transitioned to match the growth of the pure salt or saccharide at high aw values. The remaining four mixtures were based on chemical composition data for different aerosol types. As

  19. Interaction of aerosol particles composed of protein and salts with water vapor: hygroscopic growth and microstructural rearrangement

    NASA Astrophysics Data System (ADS)

    Mikhailov, E.; Vlasenko, S.; Niessner, R.; Pöschl, U.

    2004-02-01

    The interaction of aerosol particles composed of the protein bovine serum albumin (BSA) and the inorganic salts sodium chloride and ammonium nitrate with water vapor has been investigated by hygroscopicity tandem differential mobility analyzer (H-TDMA) experiments complemented by transmission electron microscopy (TEM) and Köhler theory calculations (100-300nm particle size range, 298K, 960hPa). BSA was chosen as a well-defined model substance for proteins and other macromolecular compounds, which constitute a large fraction of the water-soluble organic component of air particulate matter.

    Pure BSA particles exhibited deliquescence and efflorescence transitions at sim35% relative humidity (RH) and a hygroscopic diameter increase by up to sim10% at 95% RH in good agreement with model calculations based on a simple parameterisation of the osmotic coefficient. Pure NaCl particles were converted from near-cubic to near-spherical shape upon interaction with water vapor at relative humidities below the deliquescence threshold (partial surface dissolution and recrystallisation), and the diameters of pure NH4NO3 particles decreased by up to 10% due to chemical decomposition and evaporation.

    Mixed NaCl-BSA and NH4NO3-BSA particles interacting with water vapor exhibited mobility equivalent diameter reductions of up to 20%, depending on particle generation, conditioning, size, and chemical composition (BSA dry mass fraction 10-90%). These observations can be explained by formation of porous agglomerates (envelope void fractions up to 50%) due to ion-protein interactions and electric charge effects on the one hand, and by compaction of the agglomerate structure due to capillary condensation effects on the other. The size of NH4NO3-BSA particles was apparently also influenced by volatilisation of NH4NO3, but not as much as for pure salt particles, i.e. the protein inhibited the decomposition of NH4NO3 or the

  20. The hygroscopicity of indoor aerosol particles

    SciTech Connect

    Wei, L.

    1993-07-01

    A system to study the hygroscopic growth of particle was developed by combining a Tandem Differential Mobility Analyzer (TDMA) with a wetted wall reactor. This system is capable of mimicking the conditions in human respiratory tract, and measuring the particle size change due to the hygroscopic growth. The performance of the system was tested with three kinds of particles of known composition, NaCl, (NH{sub 4}){sub 2}SO{sub 4}, and (NH{sub 4})HS0{sub 4} particles. The hygroscopicity of a variety of common indoor aerosol particles was studied including combustion aerosols (cigarette smoking, cooking, incenses and candles) and consumer spray products such as glass cleaner, general purpose cleaner, hair spray, furniture polish spray, disinfectant, and insect killer. Experiments indicate that most of the indoor aerosols show some hygroscopic growth and only a few materials do not. The magnitude of hygroscopic growth ranges from 20% to 300% depending on the particle size and fraction of water soluble components.

  1. The Life Cycle of Stratospheric Aerosol Particles

    NASA Technical Reports Server (NTRS)

    Hamill, Patrick; Jensen, Eric J.; Russell, P. B.; Bauman, Jill J.

    1997-01-01

    This paper describes the life cycle of the background (nonvolcanic) stratospheric sulfate aerosol. The authors assume the particles are formed by homogeneous nucleation near the tropical tropopause and are carried aloft into the stratosphere. The particles remain in the Tropics for most of their life, and during this period of time a size distribution is developed by a combination of coagulation, growth by heteromolecular condensation, and mixing with air parcels containing preexisting sulfate particles. The aerosol eventually migrates to higher latitudes and descends across isentropic surfaces to the lower stratosphere. The aerosol is removed from the stratosphere primarily at mid- and high latitudes through various processes, mainly by isentropic transport across the tropopause from the stratosphere into the troposphere.

  2. Interaction of aerosol particles composed of protein and salts with water vapor: hygroscopic growth and microstructural rearrangement

    NASA Astrophysics Data System (ADS)

    Mikhailov, E.; Vlasenko, S.; Niessner, R.; Pöschl, U.

    2003-09-01

    decomposition products NH3 and HNO3. The efflorescence threshold of NaCl-BSA particles decreased with increasing BSA dry mass fraction, i.e. the protein inhibited the formation of salt crystals and enhanced the stability of supersaturated solution droplets. The H-TDMA and TEM results indicate that the protein was enriched at the surface of the mixed particles and formed an envelope, which inhibits the access of water vapor to the particle core and leads to kinetic limitations of hygroscopic growth, phase transitions, and microstructural rearrangement processes. Besides these surface and kinetic effects, proteins and comparable organic macromolecules may also influence the thermodynamic properties of the aqueous bulk solution (solubilities, vapor pressures, and chemical equilibria, e.g. for the decomposition and evaporation of NH4NO3. The observed effects should be taken into account in the analysis of data from laboratory experiments and field measurements and in the modelling of aerosol processes involving water vapor and particles with complex composition. They can strongly influence experimental results, and depending on ambient conditions they may also play a significant role in the atmosphere (deliquescence, efflorescence, and CCN activation of particles). In fact, irregular hygroscopic growth curves similar to the ones observed in this study have recently been reported from H-TDMA experiments with water-soluble organics extracted from real air particulate matter and with humic-like substances. The Köhler theory calculations performed with different models demonstrate that the hygroscopic growth of particles composed of inorganic salts and proteins can be efficiently described with a simple volume additivity approach, provided that the correct dry solute mass equivalent diameter and composition are known. A simple parameterisation of the osmotic coefficient has been derived from an osmotic pressure virial equation and appears to be well-suited for proteins and comparable

  3. Laser-Assisted Analysis of Aerosol Particles

    NASA Technical Reports Server (NTRS)

    Sinha, M. P.; Giffin, C. E.; Norris, D. D.; Friedlander, S. K.

    1985-01-01

    Proposed instrument makes rapid mass-spectrometric analyses of individual particles in aerosols. Each particle vaporized and ionized by intense laser pulse, which creates ions of minimum complexity. Ability to analyze single aerosol particles continuously makes technique suitable for detection of toxic aerosol particles on real-time basis and for identification of their sources.

  4. Vapor scavenging by atmospheric aerosol particles

    SciTech Connect

    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.

  5. Wind reduction by aerosol particles

    NASA Astrophysics Data System (ADS)

    Jacobson, Mark Z.; Kaufman, Yoram J.

    2006-12-01

    Aerosol particles are known to affect radiation, temperatures, stability, clouds, and precipitation, but their effects on spatially-distributed wind speed have not been examined to date. Here, it is found that aerosol particles, directly and through their enhancement of clouds, may reduce near-surface wind speeds below them by up to 8% locally. This reduction may explain a portion of observed ``disappearing winds'' in China, and it decreases the energy available for wind-turbine electricity. In California, slower winds reduce emissions of wind-driven soil dust and sea spray. Slower winds and cooler surface temperatures also reduce moisture advection and evaporation. These factors, along with the second indirect aerosol effect, may reduce California precipitation by 2-5%, contributing to a strain on water supply.

  6. Incorporation of new particle formation and early growth treatments into WRF/Chem: Model improvement, evaluation, and impacts of anthropogenic aerosols over East Asia

    NASA Astrophysics Data System (ADS)

    Cai, Changjie; Zhang, Xin; Wang, Kai; Zhang, Yang; Wang, Litao; Zhang, Qiang; Duan, Fengkui; He, Kebin; Yu, Shao-Cai

    2016-01-01

    New particle formation (NPF) provides an important source of aerosol particles and cloud condensation nuclei, which may result in enhanced cloud droplet number concentration (CDNC) and cloud shortwave albedo. In this work, several nucleation parameterizations and one particle early growth parameterization are implemented into the online-coupled Weather Research and Forecasting model coupled with chemistry (WRF/Chem) to improve the model's capability in simulating NPF and early growth of ultrafine particles over East Asia. The default 8-bin over the size range of 39 nm-10 μm used in the Model for Simulating Aerosol Interactions and Chemistry aerosol module is expanded to the 12-bin over 1 nm-10 μm to explicitly track the formation and evolution of new particles. Although model biases remain in simulating H2SO4, condensation sink, growth rate, and formation rate, the evaluation of July 2008 simulation identifies a combination of three nucleation parameterizations (i.e., COMB) that can best represent the atmospheric nucleation processes in terms of both surface nucleation events and the resulting vertical distribution of ultrafine particle concentrations. COMB consists of a power law of Wang et al. (2011) based on activation theory for urban areas in planetary boundary layer (PBL), a power law of Boy et al. (2008) based on activation theory for non-urban areas in PBL, and the ion-mediated nucleation parameterization of YU10 for above PBL. The application and evaluation of the improved model with 12-bin and the COMB nucleation parameterization in East Asia during January, April, July, and October in 2001 show that the model has an overall reasonably good skill in reproducing most observed meteorological variables and surface and column chemical concentrations. Relatively large biases in simulated precipitation and wind speeds are due to inaccurate surface roughness and limitations in model treatments of cloud formation and aerosol-cloud-precipitation interactions

  7. Phase transformation and growth of hygroscopic aerosols

    SciTech Connect

    Tang, I.N.

    1995-09-01

    Ambient aerosols frequently contain large portions of hygroscopic inorganic salts such as chlorides, nitrates, and sulfates in either pure or mixed forms. Such inorganic salt aerosols exhibit the properties of deliquescence and efflorescence in air. The phase transformation from a solid particle to a saline droplet usually occurs spontaneously when the relative humidity of the atmosphere reaches a level specific to the chemical composition of the aerosol particle. Conversely, when the relative humidity decreases and becomes low enough, the saline droplet will evaporate and suddenly crystallize, expelling all its water content. The phase transformation and growth of aerosols play an important role in many atmospheric processes affecting air quality, visibility degradation, and climate changes. In this chapter, an exposition of the underlying thermodynamic principles is given, and recent advances in experimental methods utilizing single-particle levitation are discussed. In addition, pertinent and available thermodynamic data, which are needed for predicting the deliquescence properties of single and multi-component aerosols, are compiled. This chapter is useful to research scientists who are either interested in pursuing further studies of aerosol thermodynamics, or required to model the dynamic behavior of hygroscopic aerosols in a humid environment.

  8. AEROSOL PARTICLE COLLECTOR DESIGN STUDY

    SciTech Connect

    Lee, S; Richard Dimenna, R

    2007-09-27

    A computational evaluation of a particle collector design was performed to evaluate the behavior of aerosol particles in a fast flowing gas stream. The objective of the work was to improve the collection efficiency of the device while maintaining a minimum specified air throughput, nominal collector size, and minimal power requirements. The impact of a range of parameters was considered subject to constraints on gas flow rate, overall collector dimensions, and power limitations. Potential improvements were identified, some of which have already been implemented. Other more complex changes were identified and are described here for further consideration. In addition, fruitful areas for further study are proposed.

  9. Test-Aerosol Generator For Calibrating Particle Counters

    NASA Technical Reports Server (NTRS)

    Mogan, Paul A.; Adams, Alois J.; Schwindt, Christian J.; Hodge, Timothy R.; Mallow, Tim J.; Duong, Anh A.; Bukauskas, Vyto V.

    1996-01-01

    Apparatus generates clean, stable aerosol stream for use in testing and calibrating laser-based aerosol-particle counter. Size and concentration of aerosol particles controlled to ensure accurate calibration. Cheap, widely available medical nebulizers used to generate aerosols.

  10. Using a combined power law and log-normal distribution model to simulate particle formation and growth in a mobile aerosol chamber

    NASA Astrophysics Data System (ADS)

    Olin, Miska; Anttila, Tatu; Dal Maso, Miikka

    2016-06-01

    We present the combined power law and log-normal distribution (PL+LN) model, a computationally efficient model to be used in simulations where the particle size distribution cannot be accurately represented by log-normal distributions, such as in simulations involving the initial steps of aerosol formation, where new particle formation and growth occur simultaneously, or in the case of inverse modeling. The model was evaluated against highly accurate sectional models using input parameter values that reflect conditions typical to particle formation occurring in the atmosphere and in vehicle exhaust. The model was tested in the simulation of a particle formation event performed in a mobile aerosol chamber at Mäkelänkatu street canyon measurement site in Helsinki, Finland. The number, surface area, and mass concentrations in the chamber simulation were conserved with the relative errors lower than 2 % using the PL+LN model, whereas a moment-based log-normal model and sectional models with the same computing time as with the PL+LN model caused relative errors up to 17 and 79 %, respectively.

  11. On the growth of ternary system HNO{sub 3}/H{sub 2}SO{sub 4}/H{sub 2} aerosol particles in the stratosphere

    SciTech Connect

    Hamill, P.; Tabazadeh, A.; Kinne, S.; Toon, O.B.

    1996-04-01

    The authors present model study results on the formation of ternary aerosols of nitric acid, sulfuric acid, and water in the stratosphere. The aerosol particles grow by means of a heteromolecular condensation process. The authors assume the particles are in equilibrium with the background water vapor.

  12. Atmospheric pressure flow reactor / aerosol mass spectrometer studies of tropospheric aerosol nucleat and growth kinetics. Final report, June, 2001

    SciTech Connect

    Worsnop, Douglas R.

    2001-06-01

    The objective of this program was to determine the mechanisms and rates of growth and transformation and growth processes that control secondary aerosol particles in both the clear and polluted troposphere. The experimental plan coupled an aerosol mass spectrometer (AMS) with a chemical ionization mass spectrometer to provide simultaneous measurement of condensed and particle phases. The first task investigated the kinetics of tropospheric particle growth and transformation by measuring vapor accretion to particles (uptake coefficients, including mass accommodation coefficients and heterogeneous reaction rate coefficients). Other work initiated investigation of aerosol nucleation processes by monitoring the appearance of submicron particles with the AMS as a function of precursor gas concentrations. Three projects were investigated during the program: (1) Ozonolysis of oleic acid aerosols as model of chemical reactivity of secondary organic aerosol; (2) Activation of soot particles by measurement deliquescence in the presence of sulfuric acid and water vapor; (3) Controlled nucleation and growth of sulfuric acid aerosols.

  13. Glassy aerosols heterogeneously nucleate cirrus ice particles

    NASA Astrophysics Data System (ADS)

    Wilson, Theodore W.; Murray, Benjamin J.; Dobbie, Steven; Cui, Zhiqiang; Al-Jumur, Sardar M. R. K.; Möhler, Ottmar; Schnaiter, Martin; Wagner, Robert; Benz, Stefan; Niemand, Monika; Saathoff, Harald; Ebert, Volker; Wagner, Steven; Kärcher, Bernd

    2010-05-01

    Ice clouds in the tropical tropopause layer (TTL, ~12-18 km, ~180-200 K) play a key role in dehydrating air entering the stratosphere. However, in-situ measurements show that air within these clouds is unexpectedly supersaturated(1); normally the growth of ice crystals rapidly quenches any supersaturation. A number of explanations for high in-cloud humidity have been put forward, but recent research suggests high humidity may be related to the low numbers of ice crystals found within these clouds(1). Low ice number densities can be produced through selective nucleation by a small subset of aerosol particles. This is inconsistent with homogeneous nucleation of ice in liquid aerosols. However, droplets rich in organic material, ubiquitous in the TTL, are known to become glassy (amorphous, non-crystalline solid) under TTL conditions(2,3). Here we show, using a large cloud simulation chamber, that glassy solution droplets nucleate ice heterogeneously at low supersaturations. Using a one-dimensional cirrus model we also show that nucleation by glassy aerosol in the TTL may explain low TTL ice number densities and high in-cloud humidity. Recent measurements of the composition of TTL cirrus residues are consistent with our findings(4). (1) Krämer, M. et al. Ice supersaturations and cirrus cloud crystal numbers. Atm. Chem. Phys. 9, 3505-3522 (2009). (2) Murray, B. J. Inhibition of ice crystallisation in highly viscous aqueous organic acid droplets. Atm. Chem. Phys. 8, 5423-5433 (2008). (3) Zobrist, B., Marcolli, C., Pedernera, D. A. & Koop, T. Do atmospheric aerosols form glasses? Atm. Chem. Phys. 8, 5221-5244 (2008). (4) Froyd, K. D., Murphy, D. M., Lawson, P., Baumgardner, D. & Herman, R. L. Aerosols that form subvisible cirrus at the tropical tropopause. Atmos. Chem. Phys. 10, 209-218 (2010).

  14. Sulfur speciation in individual aerosol particles

    NASA Astrophysics Data System (ADS)

    Neubauer, Kenneth R.; Sum, Stephen T.; Johnston, Murray V.; Wexler, Anthony S.

    1996-08-01

    Sulfur aerosols play an important role in acid deposition and the Earth's energy balance. Important species in these aerosols include methanesulfonates, hydroxymethanesulfonates, sulfates, and sulfites. Because the relative amounts of these species indicate different sources and atmospheric processes, it is important to distinguish them in single-aerosol particles. To accomplish this task, we use rapid single-particle mass spectrometry (RSMS), a technique that permits individual particles to be analyzed in an online mode. Each sulfur species produces a characteristic set of ions in the mass spectra. In simulated marine and urban aerosols the relative amounts of methanesulfonic acid (MSA) and sodium hydroxymethanesulfonate (NaHMSA) in a single particle can be determined from peak area ratios in the mass spectra. Improved quantitation is possible by application of the classification and regression tree (CART) algorithm to distinguish the mass spectra of particles having different compositions. Factors that influence speciation include particle size, morphology, and laser fluence.

  15. A numerical determination of the evolution of cloud drop spectra due to condensation on natural aerosol particles

    NASA Technical Reports Server (NTRS)

    Lee, I. Y.; Haenel, G.; Pruppacher, H. R.

    1980-01-01

    The time variation in size of aerosol particles growing by condensation is studied numerically by means of an air parcel model which allows entrainment of air and aerosol particles. Particles of four types of aerosols typically occurring in atmospheric air masses were considered. The present model circumvents any assumption about the size distribution and chemical composition of the aerosol particles by basing the aerosol particle growth on actually observed size distributions and on observed amounts of water taken up under equilibrium by a deposit of the aerosol particles. Characteristic differences in the drop size distribution, liquid water content and supersaturation were found for the clouds which evolved from the four aerosol types considered.

  16. Laboratory Experiments and Instrument Intercomparison Studies of Carbonaceous Aerosol Particles

    SciTech Connect

    Davidovits, Paul

    2015-10-20

    ) two well-characterized source of soot particles and (b) a flow reactor for controlled OH and/or O3 oxidation of relevant gas phase species to produce well-characterized SOA particles. After formation, the aerosol particles are subjected to physical and chemical processes that simulate aerosol growth and aging. A suite of instruments in our laboratory is used to characterize the physical and chemical properties of aerosol particles before and after processing. The Time of Flight Aerosol Mass Spectrometer (ToF-AMS) together with a Scanning Mobility Particle Sizer (SMPS) measures particle mass, volume, density, composition (including black carbon content), dynamic shape factor, and fractal dimension. The–ToF-AMS was developed at ARI with Boston College participation. About 120 AMS instruments are now in service (including 5 built for DOE laboratories) performing field and laboratory studies world-wide. Other major instruments include a thermal denuder, two Differential Mobility Analyzers (DMA), a Cloud Condensation Nuclei Counter (CCN), a Thermal desorption Aerosol GC/MS (TAG) and the new Soot Particle Aerosol Mass Spectrometer (SP-AMS). Optical instrumentation required for the studies have been brought to our laboratory as part of ongoing and planned collaborative projects with colleagues from DOE, NOAA and university laboratories. Optical instruments that will be utilized include a Photoacoustic Spectrometer (PAS), a Cavity Ring Down Aerosol Extinction Spectrometer (CRD-AES), a Photo Thermal Interferometer (PTI), a new 7-wavelength Aethalometer and a Cavity Attenuated Phase Shift Extinction Monitor (CAPS). These instruments are providing aerosol absorption, extinction and scattering coefficients at a range of atmospherically relevant wavelengths. During the past two years our work has continued along the lines of our original proposal. We report on 12 completed and/or continuing projects conducted during the period 08/14 to 0814/2015. These projects are described in

  17. Characteristics of aerosolized ice forming marine biogenic particles

    NASA Astrophysics Data System (ADS)

    Alpert, Peter A.

    Ice particles are ubiquitous in the atmosphere existing as the sole constituents of glaciated cirrus clouds or coexisting with supercooled liquid droplets in mixed-phase clouds. Aerosol particles serving as heterogeneous ice nuclei for ice crystal formation impact the global radiative balance by modification of cloud radiative properties, and thus climate. Atmospheric ice formation is not a well understood process and represents great uncertainty for climate prediction. The oceans which cover the majority of the earth's surface host nearly half the total global primary productivity and contribute to the greatest aerosol production by mass. However, the effect of biological activity on particle aerosolization, particle composition, and ice nucleation is not well established. This dissertation investigates the link between marine biological activity, aerosol particle production, physical/chemical particle characteristics, and ice nucleation under controlled laboratory conditions. Dry and humidified aerosol size distributions of particles from bursting bubbles generated by plunging water jets and aeration through frits in a seawater mesocosm containing bacteria and/or phytoplankton cultures, were measured as a function of biological activity. Total particle production significantly increases primarily due to enhanced aerosolization of particles ≤100 nm in diameter attributable to the presence and growth of phytoplankton. Furthermore, hygroscopicity measurements indicate primary organic material associated with the sea salt particles, providing additional evidence for the importance of marine biological activity for ocean derived aerosol composition. Ice nucleation experiments show that these organic rich particles nucleate ice efficiently in the immersion and deposition modes, which underscores their importance in mixed-phase and cirrus cloud formation processes. In separate ice nucleation experiments employing pure cultures of Thalassiosira pseudonana, Nannochloris

  18. Standard aerosols for particle velocimeters

    NASA Technical Reports Server (NTRS)

    Deepark, A.; Ozarski, R.; Thomson, J. A. L.

    1976-01-01

    System consists of laser-scattering counter (LSC) and photographic system. Photographic system provides absolute method of measuring aerosol size-distribution independently of their light scattering properties. LSC comprises 1-mW He/Ne laser, input optics, collecting optics, photodetector, and signal-processing electronics.

  19. Photochemical Aging of Organic Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Nizkorodov, S. A.; Bateman, A. P.; Dailo, M.; Do, T.; Mang, S. A.; Pan, X.; Underwood, J. S.; Walser, M. L.

    2007-05-01

    Secondary Organic Aerosol (SOA) particles are produced in the atmosphere as a result of oxidation of volatile organic compounds (VOC). Primary Organic Aerosol (POA) particles are directly emitted in the atmosphere by their sources. This research focuses on the mechanisms of direct photochemical processes taking place in model SOA and POA particles, the role of such processes in aging of organic aerosol particles, and the effect of photochemistry on particles' physicochemical properties. To address these questions, artificial SOA and POA particles are investigated with several laboratory-based approaches relying on cavity ring-down spectroscopy and mass-spectrometry. SOA particles generated by dark oxidation of d-Limonene, alpha-Pinene, and beta-Pinene by ozone are all found to absorb radiation in the tropospheric actinic window. The UV absorption photolyzes SOA constituents resulting in a release of small VOC molecules back in the gas-phase, and considerable change in SOA chemical composition. For terpenes featuring a terminal double bond, the main SOA photolysis products are invariably found to be formaldehyde and formic acid. Similar observations are obtained for products of ozonolysis of thin films of unsaturated fatty acids and self-assembled monolayers of unsaturated alkenes. For the case of fatty acids, a very detailed mechanism of ozonolysis and subsequent photolysis is proposed. The photolytic activity is primarily attributed to organic peroxides and aldehydes. These results convincingly demonstrate that photochemical processes occurring inside SOA and POA particles age the particles on time scales that are shorter than typical lifetimes of aerosol particles in the atmosphere.

  20. Particle size dependent response of aerosol counters

    NASA Astrophysics Data System (ADS)

    Ankilov, A.; Baklanov, A.; Colhoun, M.; Enderle, K.-H.; Gras, J.; Julanov, Yu.; Kaller, D.; Lindner, A.; Lushnikov, A. A.; Mavliev, R.; McGovern, F.; O'Connor, T. C.; Podzimek, J.; Preining, O.; Reischl, G. P.; Rudolf, R.; Sem, G. J.; Szymanski, W. W.; Vrtala, A. E.; Wagner, P. E.; Winklmayr, W.; Zagaynov, V.

    During an international workshop at the Institute for Experimental Physics of the University of Vienna, Austria, which was coordinated within the Committee on Nucleation and Atmospheric Aerosols (IAMAS-IUGG), 10 instruments for aerosol number concentration measurement were studied, covering a wide range of methods based on various different measuring principles. In order to investigate the detection limits of the instruments considered with respect to particle size, simultaneous number concentration measurements were performed for monodispersed aerosols with particle sizes ranging from 1.5 to 50 nm diameter and various compositions. The instruments considered show quite different response characteristics, apparently related to the different vapors used in the various counters to enlarge the particles to an optically detectable size. A strong dependence of the 50% cutoff diameter on the particle composition in correlation with the type of vapor used in the specific instrument was found. An enhanced detection efficiency for ultrafine hygroscopic sodium chloride aerosols was observed with water operated systems, an analogous trend was found for n-butanol operated systems with nonhygroscopic silver and tungsten oxide particles.

  1. New Particle Formation and Secondary Organic Aerosol in Beijing

    NASA Astrophysics Data System (ADS)

    Hu, M.; Yue, D.; Guo, S.; Hu, W.; Huang, X.; He, L.; Wiedensohler, A.; Zheng, J.; Zhang, R.

    2011-12-01

    Air pollution in Beijing has been a major concern due to being a mega-city and green Olympic Games requirements. Both long term and intensive field measurements have been conducted at an Urban Air Quality Monitoring Station in the campus of Peking University since 2004. Aerosol characteristics vary seasonally depending on meteorological conditions and source emissions. Secondary compositions of SNA (sum of sulfate, nitrate, and ammonium) and SOA (secondary organic aerosol) become major fraction of fine particles, which may enhance aerosol impacts on visibility and climate change. The transformation processes of new particle formation (NPF) and secondary organic aerosol have been focused on. It was found that gaseous sulfuric acid, ammonia, and organic compounds are important precursors to NPF events in Beijing and H2SO4-NH3-H2O ternary nucleation is one of the important mechanisms. The contributions of condensation and neutralization of sulfuric acid, coagulation, and organics to the growth of the new particles are estimated as 45%, 34%, and 21%, respectively. Tracer-based method to estimate biogenic and anthropogenic SOA was established by using gas chromatography-mass spectrometry. Secondary organic tracers derived from biogenic (isoprene, α-pinene, β-caryophyllene) and anthropogenic (toluene) contributed 32% at urban site and 35% at rural site, respectively. Other source apportionment techniques were also used to estimate secondary organic aerosols, including EC tracer method, water soluble organic carbon content, chemical mass balance model, and AMS-PMF method.

  2. Aerosol particle analysis by Raman scattering technique

    SciTech Connect

    Fung, K.H.; Tang, I.N.

    1992-10-01

    Laser Raman spectroscopy is a very versatile tool for chemical characterization of micron-sized particles. Such particles are abundant in nature, and in numerous energy-related processes. In order to elucidate the formation mechanisms and understand the subsequent chemical transformation under a variety of reaction conditions, it is imperative to develop analytical measurement techniques for in situ monitoring of these suspended particles. In this report, we outline our recent work on spontaneous Raman, resonance Raman and non-linear Raman scattering as a novel technique for chemical analysis of aerosol particles as well as supersaturated solution droplets.

  3. Alternative pathway for atmospheric particles growth.

    PubMed

    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. PMID:22517749

  4. Alternative pathway for atmospheric particles growth.

    PubMed

    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. Alternative pathway for atmospheric particles growth

    PubMed Central

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

    2012-01-01

    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. PMID:22517749

  6. Composition and formation of organic aerosol particles in the Amazon

    NASA Astrophysics Data System (ADS)

    Pöhlker, C.; Wiedemann, K.; Sinha, B.; Shiraiwa, M.; Gunthe, S. S.; Artaxo, P.; Gilles, M. K.; Kilcoyne, A. L. D.; Moffet, R. C.; Smith, M.; Weigand, M.; Martin, S. T.; Pöschl, U.; Andreae, M. O.

    2012-04-01

    We applied scanning transmission X-ray microscopy with near edge X-ray absorption fine structure (STXM-NEXAFS) analysis to investigate the morphology and chemical composition of aerosol samples from a pristine tropical environment, the Amazon Basin. The samples were collected in the Amazonian rainforest during the rainy season and can be regarded as a natural background aerosol. The samples were found to be dominated by secondary organic aerosol (SOA) particles in the fine and primary biological aerosol particles (PBAP) in the coarse mode. Lab-generated SOA-samples from isoprene and terpene oxidation as well as pure organic compounds from spray-drying of aqueous solution were measured as reference samples. The aim of this study was to investigate the microphysical and chemical properties of a tropical background aerosol in the submicron size range and its internal mixing state. The lab-generated SOA and pure organic compounds occurred as spherical and mostly homogenous droplet-like particles, whereas the Amazonian SOA particles comprised a mixture of homogeneous droplets and droplets having internal structures due to atmospheric aging. In spite of the similar morphological appearance, the Amazon samples showed considerable differences in elemental and functional group composition. According to their NEXAFS spectra, three chemically distinct types of organic material were found and could be assigned to the following three categories: (1) particles with a pronounced carboxylic acid (COOH) peak similar to those of laboratory-generated SOA particles from terpene oxidation; (2) particles with a strong hydroxy (COH) signal similar to pure carbohydrate particles; and (3) particles with spectra resembling a mixture of the first two classes. In addition to the dominant organic component, the NEXAFS spectra revealed clearly resolved potassium (K) signals for all analyzed particles. During the rainy season and in the absence of anthropogenic influence, active biota is

  7. Phase transitions and morphologies of aerosol particles

    NASA Astrophysics Data System (ADS)

    Song, M.; Marcolli, C.; Krieger, U.; Zuend, A.; Peter, T.

    2012-12-01

    Tropospheric aerosol particles consisting of complex mixtures of organic compounds, ammonium sulfate (AS) and water undergo phase transitions such as liquid-liquid phase separation (LLPS), efflorescence and deliquescence as a consequence of changes in ambient relative humidity (RH). These phase transitions in the mixed aerosol particles may lead to different particle configurations such as core-shell or partially engulfed structures. However, the physical states and morphologies of these aerosol particles are still poorly understood. In this study, we investigate the phase transitions and morphological changes of various internally mixed organics/AS/water particles with different organic-to-inorganic ratios (OIR), namely OIR = 6:1, 2:1, 1:2 and 1:6 during humidity cycles using optical microscopy and Raman spectroscopy. Particularly, we explore how the properties of different organic functional groups and the compositional complexity of the organic aerosol fraction influence the occurrence of LLPS in the relationship with the organic oxygen-to-carbon (O:C) ratios. We found that LLPS occurred for all mixtures with O:C < 0.56, for none of the mixtures with O:C > 0.80, and depended on the specific types and compositions of organic functional groups for 0.56 < O:C < 0.80. Moreover, the number of mixture components and the spread of the O:C range did not notably influence the conditions for LLPS to occur. Since in ambient aerosols O:C and OIR range typically between 0.2 and 1.0, and between 4:1 and 1:5, respectively, LLPS is expected to be a common feature of tropospheric aerosols. AS in the mixed particles effloresced between 0 and 47 %RH and deliquesced between 71 and 80 %RH during humidity cycles. Compared to a deliquescence relative humidity (DRH) of 80 % for pure AS, the DRH in the mixed particles showed slightly lower values. A strong reduction or complete inhibition of efflorescence occurred for mixtures with high OIR that did not exhibit LLPS. Both core-shell and

  8. Sources and transformations of atmospheric aerosol particles

    NASA Astrophysics Data System (ADS)

    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

  9. Fatty Acids as Surfactants on Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Tervahattu, H.; Juhanoja, J.; Niemi, J.

    2003-12-01

    Fatty acids (n-alcanoic acids) are common compounds in numerous anthropogenic and natural emissions. According to Rogge et al. (1993), catalyst-equipped automobiles emitted more than 600 μg km-1 of fatty acids which was over 50% of all identified organics in fine aerosol emissions. Coal burning produces fatty acids ranging from about 1700 mg kg-1 for bituminous coal to over 10000 mg kg-1 for lignite (Oros and Simoneit, 2000). Similarly, biomass burning is an important source for aerosol fatty acids. They are the major identified compound group in deciduous tree smoke, their total emission factor being measured as 1589 mg kg-1 which was 56% of all identified organic compounds (Oros and Simoneit, 2001a). Large amounts of fatty acid are also emitted from burning of conifer trees and grass (Oros and Simoneit, 2001a; Simoneit, 2002). Fatty acids have been reported to be major constituents of marine aerosols in many investigations (Barger and Garrett, 1976; Gagosian et. al, 1981; Sicre et al., 1990; Stephanou, 1992). It has been suggested that as the marine aerosol particles form, they acquire a coating of organic surfactants (Blanchard, 1964; Gill et al., 1983; Middlebrook et al., 1998; Ellison et al., 1999). Amphiphilic molecules, including lipids, can be assembled as monomolecular layers at air/water interfaces as well as transported to a solid support. Recently, we could show by time-of-flight secondary ion mass spectrometry that fatty acids are important ingredients of the outermost surface layer of the sea-salt aerosol particles (Tervahattu et al., 2002). In their TOF-SIMS studies on the surface composition of atmospheric aerosols, Peterson and Tyler (2002) found fatty acids on the surface of Montana forest fire particles. In this work we have studied by TOF-SIMS the surface chemical composition of aerosol particles emitted from field fires in the Baltic and other East European countries and transported to Finland as well as aerosol particles transported from

  10. Sulfur speciation of single aerosol particles

    SciTech Connect

    Neubauer, K.R.; Sum, S.T.; Johnston, M.V.; Wexler, A.S.

    1995-12-31

    Sulfur enters the atmosphere as gaseous species emitted from both natural and anthropogenic sources. These species can undergo a variety of oxidation reactions that ultimately yield hexavalent sulfur aerosols. Since the final products play an important role in acid rain production and the earth`s energy balance, it is important to distinguish tetravalent and hexavalent sulfur aerosols, as well as differentiate those arising from natural and anthropogenic sources. To attain these goals the authors chose to examine five target compounds that are present in the atmosphere: sodium sulfate, ammonium sulfate, ammonium sulfite, methanesulfonic acid (MSA), and the sodium salt of hydroxymethanesulfonic acid (NaHMSA). Sodium sulfate is observed in oceanic aerosols, while both ammonium salts are observed over land. MSA is found only in the marine environment and originates solely from natural emissions, while HMSA is formed in urban hazes and primarily arises from anthropogenic sources. Thus, MSA and HMSA serve as tracers for distinguishing natural and anthropogenic sulfur emissions. To differentiate these compounds, the authors used Rapid Single-Particle Mass Spectrometry (RSMS), a method that allows single particles to be analyzed on-line and in real time. With RSMS, particles are drawn directly into the source region of a reflectron time-of-flight mass spectrometer where they are detected by light scattering of a continuous laser beam and then ablated by an excimer laser pulse. With this sequence of events, each mass spectrum results from a single laser pulse ablating a single particle.

  11. Temporal Variation of Aerosol Properties at a Rural Continental Site and Study of Aerosol Evolution through Growth Law Analysis

    NASA Technical Reports Server (NTRS)

    Wang, Jian; Collins, Don; Covert, David; Elleman, Robert; Ferrare, Richard A.; Gasparini, Roberto; Jonsson, Haflidi; Ogren, John; Sheridan, Patrick; Tsay, Si-Chee

    2006-01-01

    Aerosol size distributions were measured by a Scanning Mobility Particle Sizer (SMPS) onboard the CIRPAS Twin Otter aircraft during 16 flights at the Southern Great Plains (SGP) site in northern central Oklahoma as part of the Aerosol Intensive Operation period in May, 2003. During the same period a second SMPS was deployed at a surface station and provided continuous measurements. Combined with trace gas measurements at the SGP site and back-trajectory analysis, the aerosol size distributions provided insights into the sources of aerosols observed at the SGP site. High particle concentrations, observed mostly during daytime, were well correlated with the sulfur dioxide (SO2) mixing ratios, suggesting nucleation involving sulfuric acid is likely the main source of newly formed particles at the SGP. Aerosols within plumes originating from wildfires in Central America were measured at the surface site. Vertically compact aerosol layers, which can be traced back to forest fires in East Asia, were intercepted at altitudes over 3000 meters. Analyses of size dependent particle growth rates for four periods during which high cloud coverage was observed indicate growth dominated by volume controlled reactions. Sulfate accounts for 50% to 72% of the increase in aerosol volume concentration; the rest of the volume concentration increase was likely due to secondary organic species. The growth law analyses and meteorological conditions indicate that the sulfate was produced mainly through aqueous oxidation of SO2 in clouds droplets and hydrated aerosol particles.

  12. Studies of Ice Nucleating Aerosol Particles in Arctic Cloud Systems

    NASA Technical Reports Server (NTRS)

    Rogers, David C.; DeMott, Paul J.; Kreidenweis, Sonia M.

    2001-01-01

    The focus of this research is to improve the understanding of ice nucleating aerosol particles (IN) and the role they play in ice formation in Arctic clouds. IN are important for global climate issues in a variety of ways. The primary effect is their role in determining the phase (liquid or solid) of cloud particles. The microscale impact is on cloud particle size, growth rate, shape, fall speed, concentration, radiative properties, and scavenging of gases and aerosols. On a larger scale, ice formation affects the development of precipitation (rate, amount, type, and distribution), latent heat release (rate and altitude), ambient humidity, the persistence of clouds, and cloud albedo. The overall goals of our FIRE 3 research are to characterize the concentrations and variability of Arctic IN during the winter-spring transition, to compare IN measurements with ice concentrations in Arctic clouds, and to examine selected IN samples for particle morphology and chemical there are distinguishable chemical signatures. The results can be combined with other measurements of aerosols, gaseous species, and cloud characteristics in order to understand the processes that determine the phase and concentration of cloud particles.

  13. Particle size distribution of indoor aerosol sources

    SciTech Connect

    Shah, K.B.

    1990-10-24

    As concern about Indoor Air Quality (IAQ) has grown in recent years, it has become necessary to determine the nature of particles produced by different indoor aerosol sources and the typical concentration that these sources tend to produce. These data are important in predicting the dose of particles to people exposed to these sources and it will also enable us to take effective mitigation procedures. Further, it will also help in designing appropriate air cleaners. A new state of the art technique, DMPS (Differential Mobility Particle Sizer) System is used to determine the particle size distributions of a number of sources. This system employs the electrical mobility characteristics of these particles and is very effective in the 0.01--1.0 {mu}m size range. A modified system that can measure particle sizes in the lower size range down to 3 nm was also used. Experimental results for various aerosol sources is presented in the ensuing chapters. 37 refs., 20 figs., 2 tabs.

  14. Generation and characterization of large-particle aerosols using a center flow tangential aerosol generator with a nonhuman-primate, head-only aerosol chamber

    PubMed Central

    Bohannon, J. Kyle; Lackemeyer, Matthew G.; Kuhn, Jens H.; Wada, Jiro; Bollinger, Laura; Jahrling, Peter B.; Johnson, Reed F.

    2016-01-01

    Aerosol droplets or particles produced from infected respiratory secretions have the potential to infect another host through inhalation. These respiratory particles can be polydisperse and range from 0.05–500 μm in diameter. Animal models of infection are generally established to facilitate the potential licensure of candidate prophylactics and/or therapeutics. Consequently, aerosol-based animal infection models are needed to properly study and counter airborne infections. Ideally, experimental aerosol exposure should reliably result in animal disease that faithfully reproduces the modelled human disease. Few studies have been performed to explore the relationship between exposure particle size and induced disease course for infectious aerosol particles. The center flow tangential aerosol generator (CenTAG™) produces large-particle aerosols capable of safely delivering a variety of infectious aerosols to nonhuman primates within a Class III Biological Safety Cabinet (BSC) for establishment or refinement of nonhuman primate infectious disease models. Here we report the adaptation of this technology to the Animal Biosafety Level 4 (ABSL-4) environment for the future study of high-consequence viral pathogens and the characterization of CenTAG™-created sham (no animal, no virus) aerosols using a variety of viral growth media and media supplements. PMID:25970823

  15. Generation and characterization of large-particle aerosols using a center flow tangential aerosol generator with a non-human-primate, head-only aerosol chamber.

    PubMed

    Bohannon, J Kyle; Lackemeyer, Matthew G; Kuhn, Jens H; Wada, Jiro; Bollinger, Laura; Jahrling, Peter B; Johnson, Reed F

    2015-01-01

    Aerosol droplets or particles produced from infected respiratory secretions have the potential to infect another host through inhalation. These respiratory particles can be polydisperse and range from 0.05 to 500 µm in diameter. Animal models of infection are generally established to facilitate the potential licensure of candidate prophylactics and/or therapeutics. Consequently, aerosol-based animal infection models are needed to properly study and counter airborne infections. Ideally, experimental aerosol exposure should reliably result in animal disease that faithfully reproduces the modeled human disease. Few studies have been performed to explore the relationship between exposure particle size and induced disease course for infectious aerosol particles. The center flow tangential aerosol generator (CenTAG™) produces large-particle aerosols capable of safely delivering a variety of infectious aerosols to non-human primates (NHPs) within a Class III Biological Safety Cabinet (BSC) for establishment or refinement of NHP infectious disease models. Here, we report the adaptation of this technology to the Animal Biosafety Level 4 (ABSL-4) environment for the future study of high-consequence viral pathogens and the characterization of CenTAG™-created sham (no animal, no virus) aerosols using a variety of viral growth media and media supplements. PMID:25970823

  16. Cooling enhancement of aerosol particles due to surfactant precipitation.

    PubMed

    Beaver, Melinda R; Freedman, Miriam A; Hasenkopf, Christa A; Tolbert, Margaret A

    2010-07-01

    Light extinction by particles in Earth's atmosphere is strongly dependent on the particle size, chemical composition, and ability to take up water. In this work, we have measured the optical growth factors, fRH(ext)(RH, dry), for complex particles composed of an inorganic salt, sodium nitrate, and an anionic surfactant, sodium dodecyl sulfate. In contrast with previous studies using soluble and slightly soluble organic compounds, optical growth in excess to that expected based on the volume weighted water uptake of the individual components is observed. We explored the relationship between optical growth and concentration of surfactant by investigating the role of particle density, the effect of a surfactant monolayer, and increased light extinction by surfactant aggregates and precipitates. For our experimental conditions, it is likely that surfactant precipitates are responsible for the observed increase in light scattering. The contribution of surfactant precipitates to light scattering of aerosol particles has not been previously explored and has significant implications for characterizing the aerosol direct effect.

  17. AEROSOL GROWTH IN A STEADY-STATE, CONTINUOUS FLOW CHAMBER: APPLICATION TO STUDIES OF SECONDARY AEROSOL FORMATION

    EPA Science Inventory

    An analytical solution for the steady-state aerosol size distribution achieved in a steady-state, continuous flow chamber is derived, where particle growth is occurring by gas-to-particle conversion and particle loss is occurring by deposition to the walls of the chamber. The s...

  18. Aerosol growth in Titan's ionosphere.

    PubMed

    Lavvas, Panayotis; Yelle, Roger V; Koskinen, Tommi; Bazin, Axel; Vuitton, Véronique; Vigren, Erik; Galand, Marina; Wellbrock, Anne; Coates, Andrew J; Wahlund, Jan-Erik; Crary, Frank J; Snowden, Darci

    2013-02-19

    Photochemically produced aerosols are common among the atmospheres of our solar system and beyond. Observations and models have shown that photochemical aerosols have direct consequences on atmospheric properties as well as important astrobiological ramifications, but the mechanisms involved in their formation remain unclear. Here we show that the formation of aerosols in Titan's upper atmosphere is directly related to ion processes, and we provide a complete interpretation of observed mass spectra by the Cassini instruments from small to large masses. Because all planetary atmospheres possess ionospheres, we anticipate that the mechanisms identified here will be efficient in other environments as well, modulated by the chemical complexity of each atmosphere. PMID:23382231

  19. The influence of meteoric smoke particles on stratospheric aerosol properties

    NASA Astrophysics Data System (ADS)

    Mann, Graham; Brooke, James; Dhomse, Sandip; Plane, John; Feng, Wuhu; Neely, Ryan; Bardeen, Chuck; Bellouin, Nicolas; Dalvi, Mohit; Johnson, Colin; Abraham, Luke

    2016-04-01

    The ablation of metors in the thermosphere and mesosphere introduces a signficant source of particulate matter into the polar upper stratosphere. These meteoric smoke particles (MSP) initially form at nanometre sizes but in the stratosphere have grown to larger sizes (tens of nanometres) following coagulation. The presence of these smoke particles may represent a significant mechanism for the nucleation of polar stratospheric clouds and are also known to influence the properties of the stratospheric aerosol or Junge layer. In this presentation we present findings from experiments to investigate the influence of the MSP on the Junge layer, carried out with the UM-UKCA composition-climate model. The UM-UKCA model is a high-top (up to 80km) version of the general circulation model with well-resolved stratospheric dynamics, includes the aerosol microphysics module GLOMAP and has interactive sulphur chemistry suitable for the stratosphere and troposphere (Dhomse et al., 2014). We have recently added to UM-UKCA a source of meteoric smoke particles, based on prescribing the variation of the smoke particles from previous simulations with the Whole Atmosphere Community Climate Model (WACCM). In UM-UKCA, the MSP particles are transported within the GLOMAP aerosol framework, alongside interactive stratospheric sulphuric acid aerosol. For the experiments presented here, we have activated the interaction between the MSP and the stratospheric sulphuric acid aerosol. The MSP provide an important sink term for the gas phase sulphuric acid simulated in the model, with subsequent effects on the formation, growth and temporal evolution of stratospheric sulphuric acid aerosol particles. By comparing simulations with and without the MSP-sulphur interactions we quantify the influence of the meteoric smoke on the properties of volcanically-quiescent Junge layer. We also investigate the extent to which the MSP may modulate the effects from SO2 injected into the stratosphere from volcanic

  20. Tracking Water Diffusion Fronts in a Highly Viscous Aerosol Particle

    NASA Astrophysics Data System (ADS)

    Bastelberger, Sandra; Krieger, Ulrich; Peter, Thomas

    2016-04-01

    Field measurements indicate that atmospheric secondary aerosol particles can be present in a highly viscous, glassy state [1]. In contrast to liquid state particles, the gas phase equilibration is kinetically limited and governed by condensed phase diffusion. In recent water diffusion experiments on highly viscous single aerosol particles levitated in an electrodynamic balance (EDB) we observed a characteristic shift behavior of the Mie whispering gallery modes (WGM) indicative of the changing radial structure of the particle, thus providing us with an experimental method to track the diffusion process inside the particle. When a highly viscous, homogeneous particle is exposed to an abrupt increase in relative humidity, the rapid gas phase diffusion and strong concentration dependence of the diffusion coefficient in the condensed phase lead to extremely steep water concentration gradients inside the particle, reminiscent of diffusion fronts. The resulting quasi step-like concentration profile motivates the introduction of a simple core-shell model describing the morphology of the non-equilibrium particle during humidification. The subsequent particle growth and reduction of the shell refractive index can be observed as red and blueshift behavior of the WGM, respectively. The shift pattern can be attributed to a core-shell radius ratio and particle radius derived from model calculations [2]. If supplemented with growth information obtained from the WGM redshift and thermodynamic equilibrium data, we can infer a comprehensive picture of the time evolution of the diffusion fronts in the framework of our core-shell model. The measured time dependent concentration profile is then compared with simulations solving the non-linear diffusion equation [3] [1] Virtanen, A., et al., Nature, 467, 824-827, 2010 [2] Kaiser, T., Schweiger, G., Computers in Physics, Vol. 7, No. 6, 682-686, Nov/Dec 1993 [3] Zobrist, B., Soonsin, V., Luo, B.P., Peter, T. et al., Phys. Chem. Chem

  1. The Impact of Aerosol Particle Mixing State on the Hygroscopicity of Sea Spray Aerosol.

    PubMed

    Schill, Steven R; Collins, Douglas B; Lee, Christopher; Morris, Holly S; Novak, Gordon A; Prather, Kimberly A; Quinn, Patricia K; Sultana, Camille M; Tivanski, Alexei V; Zimmermann, Kathryn; Cappa, Christopher D; Bertram, Timothy H

    2015-06-24

    Aerosol particles influence global climate by determining cloud droplet number concentrations, brightness, and lifetime. Primary aerosol particles, such as those produced from breaking waves in the ocean, display large particle-particle variability in chemical composition, morphology, and physical phase state, all of which affect the ability of individual particles to accommodate water and grow into cloud droplets. Despite such diversity in molecular composition, there is a paucity of methods available to assess how particle-particle variability in chemistry translates to corresponding differences in aerosol hygroscopicity. Here, an approach has been developed that allows for characterization of the distribution of aerosol hygroscopicity within a chemically complex population of atmospheric particles. This methodology, when applied to the interpretation of nascent sea spray aerosol, provides a quantitative framework for connecting results obtained using molecular mimics generated in the laboratory with chemically complex ambient aerosol. We show that nascent sea spray aerosol, generated in situ in the Atlantic Ocean, displays a broad distribution of particle hygroscopicities, indicative of a correspondingly broad distribution of particle chemical compositions. Molecular mimics of sea spray aerosol organic material were used in the laboratory to assess the volume fractions and molecular functionality required to suppress sea spray aerosol hygroscopicity to the extent indicated by field observations. We show that proper accounting for the distribution and diversity in particle hygroscopicity and composition are important to the assessment of particle impacts on clouds and global climate.

  2. The Impact of Aerosol Particle Mixing State on the Hygroscopicity of Sea Spray Aerosol.

    PubMed

    Schill, Steven R; Collins, Douglas B; Lee, Christopher; Morris, Holly S; Novak, Gordon A; Prather, Kimberly A; Quinn, Patricia K; Sultana, Camille M; Tivanski, Alexei V; Zimmermann, Kathryn; Cappa, Christopher D; Bertram, Timothy H

    2015-06-24

    Aerosol particles influence global climate by determining cloud droplet number concentrations, brightness, and lifetime. Primary aerosol particles, such as those produced from breaking waves in the ocean, display large particle-particle variability in chemical composition, morphology, and physical phase state, all of which affect the ability of individual particles to accommodate water and grow into cloud droplets. Despite such diversity in molecular composition, there is a paucity of methods available to assess how particle-particle variability in chemistry translates to corresponding differences in aerosol hygroscopicity. Here, an approach has been developed that allows for characterization of the distribution of aerosol hygroscopicity within a chemically complex population of atmospheric particles. This methodology, when applied to the interpretation of nascent sea spray aerosol, provides a quantitative framework for connecting results obtained using molecular mimics generated in the laboratory with chemically complex ambient aerosol. We show that nascent sea spray aerosol, generated in situ in the Atlantic Ocean, displays a broad distribution of particle hygroscopicities, indicative of a correspondingly broad distribution of particle chemical compositions. Molecular mimics of sea spray aerosol organic material were used in the laboratory to assess the volume fractions and molecular functionality required to suppress sea spray aerosol hygroscopicity to the extent indicated by field observations. We show that proper accounting for the distribution and diversity in particle hygroscopicity and composition are important to the assessment of particle impacts on clouds and global climate. PMID:27162963

  3. Water Activity Limits the Hygroscopic Growth Factor of Organic Aerosols

    NASA Astrophysics Data System (ADS)

    Rodriguez, L. I.; Cabrera, J. A.; Golden, D.; Tabazadeh, A.

    2007-12-01

    In this work we study the hygroscopic behavior of organic aerosols, which has important implications for Earth's climate. The hygroscopic growth factor (HGF) is defined as the ratio of the diameter of a spherical particle when it is exposed to dry conditions to that at humid conditions. We present a new formulation to express the HGF of an aerosol particle as a function of water activity (aw) in the aqueous phase. This new formulation matches reported HGFs for common inorganic salts and water-miscible organic particles that are known to deliquesce into aqueous drops at high relative humidities (RH). Many studies use tandem differential mobility analyzers (TDMA) to determine the HGF of organic aerosols. For example, Brooks et al. used a TDMA to measure a HGF of 1.2 for 2 μm phthalic acid (PA) particles at 90% RH (aw= 0.9). However, water activity limits the growth of a particle that can be attributed to water uptake. We have assembled a vapor pressure apparatus to measure aw of aqueous solutions at room temperature. Measured water activities for PA, used in our growth formulation, yield a HGF of ~ 1.0005 for 2 μm PA particles at 90% RH. Comparing our results against Brooks et al. suggests that TDMA experiments may grossly overestimate the HGF of PA particles since water activity limits this growth to below 1.0005. Alternatively, we suggest that the adsorption of a negligible mass of water by a highly porous PA particle can lead to an apparent growth in particle size by changing its morphology. Other studies also use TDMAs to measure HGFs of secondary organic aerosols (SOAs). HGFs reported for SOAs are very similar to PA, suggesting that the observed growth may be due to morphological changes in particle size rather than water uptake as commonly assumed. We built a smog chamber where an organic precursor, such as d-limonene, reacts with nitrogen oxides under UV radiation to produce SOAs. We compare the HGFs for SOAs obtained with our method to those obtained with

  4. The Impact of Aerosol Particle Mixing State on the Hygroscopicity of Sea Spray Aerosol

    PubMed Central

    2015-01-01

    Aerosol particles influence global climate by determining cloud droplet number concentrations, brightness, and lifetime. Primary aerosol particles, such as those produced from breaking waves in the ocean, display large particle–particle variability in chemical composition, morphology, and physical phase state, all of which affect the ability of individual particles to accommodate water and grow into cloud droplets. Despite such diversity in molecular composition, there is a paucity of methods available to assess how particle–particle variability in chemistry translates to corresponding differences in aerosol hygroscopicity. Here, an approach has been developed that allows for characterization of the distribution of aerosol hygroscopicity within a chemically complex population of atmospheric particles. This methodology, when applied to the interpretation of nascent sea spray aerosol, provides a quantitative framework for connecting results obtained using molecular mimics generated in the laboratory with chemically complex ambient aerosol. We show that nascent sea spray aerosol, generated in situ in the Atlantic Ocean, displays a broad distribution of particle hygroscopicities, indicative of a correspondingly broad distribution of particle chemical compositions. Molecular mimics of sea spray aerosol organic material were used in the laboratory to assess the volume fractions and molecular functionality required to suppress sea spray aerosol hygroscopicity to the extent indicated by field observations. We show that proper accounting for the distribution and diversity in particle hygroscopicity and composition are important to the assessment of particle impacts on clouds and global climate. PMID:27162963

  5. Characteristics of Chinese aerosols determined by individual-particle analysis

    NASA Astrophysics Data System (ADS)

    Gao, Yuan; Anderson, James R.

    2001-08-01

    Tropospheric aerosols that originate in China and are transported over the North Pacific Ocean have potentially significant impacts on regional and global climate. These aerosols are complex mixtures of soil dust and anthropogenic particles from a variety of sources, including fossil fuel combustion, biomass burning, mining, smelting, and other industrial processes, plus reaction products of heterogeneous processes that affect these particles during transport. In the coastal marine atmosphere, these particles could be further mixed with marine aerosols. To provide examples of the diversity of chemical and physical properties of east Asian aerosols in the spring, individual aerosol particle samples were collected in April and May 1999 in three different environments in China: Qingdao on the coast of the East China Sea, Beijing in the northeast interior, and Mount Waliguan in remote northwestern China. Results reveal that aerosols in this region are complex and heterogeneous. In addition to significant differences in aerosol composition and size distributions among the samples, each sample contains a large number of polyphase aggregates. Many of the particles also have irregular shapes; for a number of the particle types, the irregular shapes should persist even at high ambient RH. Because composition, degree and nature of polyphase aggregation, and shape all effect aerosol radiative properties, the complex state of east Asian aerosols presents a challenge for the modeling of aerosol radiative forcing in the region.

  6. Chemistry and Composition of Atmospheric Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Kolb, Charles E.; Worsnop, Douglas R.

    2012-05-01

    For more than two decades a cadre of physical chemists has focused on understanding the formation processes, chemical composition, and chemical kinetics of atmospheric aerosol particles and droplets with diameters ranging from a few nanometers to ˜10,000 nm. They have adapted or invented a range of fundamental experimental and theoretical tools to investigate the thermochemistry, mass transport, and chemical kinetics of processes occurring at nanoscale gas-liquid and gas-solid interfaces for a wide range of nonideal, real-world substances. State-of-the-art laboratory methods devised to study molecular spectroscopy, chemical kinetics, and molecular dynamics also have been incorporated into field measurement instruments that are deployed routinely on research aircraft, ships, and mobile laboratories as well as at field sites from megacities to the most remote jungle, desert, and polar locations. These instruments can now provide real-time, size-resolved aerosol particle physical property and chemical composition data anywhere in Earth's troposphere and lower stratosphere.

  7. Workplace aerosol mass concentration measurement using optical particle counters.

    PubMed

    Görner, Peter; Simon, Xavier; Bémer, Denis; Lidén, Göran

    2012-02-01

    Direct-reading aerosol measurement usually uses the optical properties of airborne particles to detect and measure particle concentration. In the case of occupational hygiene, mass concentration measurement is often required. Two aerosol monitoring methods are based on the principle of light scattering: optical particle counting (OPC) and photometry. The former analyses the light scattered by a single particle, the latter by a cloud of particles. Both methods need calibration to transform the quantity of scattered light detected into particle concentration. Photometers are simpler to use and can be directly calibrated to measure mass concentration. However, their response varies not only with aerosol concentration but also with particle size distribution, which frequently contributes to biased measurement. Optical particle counters directly measure the particle number concentration and particle size that allows assessment of the particle mass provided the particles are spherical and of known density. An integrating algorithm is used to calculate the mass concentration of any conventional health-related aerosol fraction. The concentrations calculated thus have been compared with simultaneous measurements by conventional gravimetric sampling to check the possibility of field OPC calibration with real workplace aerosols with a view to further monitoring particle mass concentration. Aerosol concentrations were measured in the food industry using the OPC GRIMM® 1.108 and the CIP 10-Inhalable and CIP 10-Respirable (ARELCO®) aerosol samplers while meat sausages were being brushed and coated with calcium carbonate. Previously, the original OPC inlet had been adapted to sample inhalable aerosol. A mixed aerosol of calcium carbonate and fungi spores was present in the workplace. The OPC particle-size distribution and an estimated average particle density of both aerosol components were used to calculate the mass concentration. The inhalable and respirable aerosol fractions

  8. Workplace aerosol mass concentration measurement using optical particle counters.

    PubMed

    Görner, Peter; Simon, Xavier; Bémer, Denis; Lidén, Göran

    2012-02-01

    Direct-reading aerosol measurement usually uses the optical properties of airborne particles to detect and measure particle concentration. In the case of occupational hygiene, mass concentration measurement is often required. Two aerosol monitoring methods are based on the principle of light scattering: optical particle counting (OPC) and photometry. The former analyses the light scattered by a single particle, the latter by a cloud of particles. Both methods need calibration to transform the quantity of scattered light detected into particle concentration. Photometers are simpler to use and can be directly calibrated to measure mass concentration. However, their response varies not only with aerosol concentration but also with particle size distribution, which frequently contributes to biased measurement. Optical particle counters directly measure the particle number concentration and particle size that allows assessment of the particle mass provided the particles are spherical and of known density. An integrating algorithm is used to calculate the mass concentration of any conventional health-related aerosol fraction. The concentrations calculated thus have been compared with simultaneous measurements by conventional gravimetric sampling to check the possibility of field OPC calibration with real workplace aerosols with a view to further monitoring particle mass concentration. Aerosol concentrations were measured in the food industry using the OPC GRIMM® 1.108 and the CIP 10-Inhalable and CIP 10-Respirable (ARELCO®) aerosol samplers while meat sausages were being brushed and coated with calcium carbonate. Previously, the original OPC inlet had been adapted to sample inhalable aerosol. A mixed aerosol of calcium carbonate and fungi spores was present in the workplace. The OPC particle-size distribution and an estimated average particle density of both aerosol components were used to calculate the mass concentration. The inhalable and respirable aerosol fractions

  9. Particle size distributions of several commonly used seeding aerosols

    NASA Technical Reports Server (NTRS)

    Crosswy, F. L.

    1985-01-01

    During the course of experimentation, no solid particle powder could be found which produced an aerosol with a narrow particle size distribution when fluidization was the only flow process used in producing the aerosol. The complication of adding particle size fractionation processes to the aerosol generation effort appears to be avoidable. In this regard, a simple sonic orifice is found to be effective in reducing the percentage of agglomerates in the several metal oxide powders tested. Marginally beneficial results are obtained for a 0.5/99.5 percent by weight mixture of the flow agent and metal oxide powder. However, agglomeration is observed to be enhanced when the flow agent percentage is increased to 5 percent. Liquid atomization using the Collison nebulizer as well as a version of the Laskin nozzle resulted in polydispersed aerosols with particle size distributions heavily weighted by the small particle end of the size spectrum. The aerosol particle size distributions produced by the vaporization/condensation seeder are closer to the ideal monodispersed aerosol than any of the other aerosols tested. In addition, this seeding approach affords a measure of control over particle size and particle production rate.

  10. Aerosol stability of infectious and potentially infectious reovirus particles.

    PubMed Central

    Adams, D J; Spendlove, J C; Spendlove, R S; Barnett, B B

    1982-01-01

    The aerosol stability of two particle forms, infectious and potentially infectious, of reovirus were examined under static conditions for a range of relative humidities at 21 and 24 degrees C. Virus aerosolization efficiency was determined for two methods of dissemination: Collison nebulizer and Chicago atomizer. Suspensions of Bacillus subtilis var. niger spores were added to reovirus preparations that included both particle forms and disseminated into a dynamic aerosol toroid to estimate the physical decay of the aerosols. At 90 to 100% relative humidity, both reovirus particle forms showed less than 10-fold loss of infectivity after 12 h of aging. At lower relative humidities the aerosol decay curve showed rapid initial decay followed by a markedly lower decay rate. Our findings reveal that reovirus particles are relatively stable in the airborne state. PMID:7149719

  11. Fatty acids on continental sulfate aerosol particles

    NASA Astrophysics Data System (ADS)

    Tervahattu, H.; Juhanoja, J.; Vaida, V.; Tuck, A. F.; Niemi, J. V.; Kupiainen, K.; Kulmala, M.; VehkamäKi, H.

    2005-03-01

    Surface analyses of atmospheric aerosols from different continental sources, such as forest fires and coal and straw burning, show that organic surfactants are found on such aerosols. The predominant organic species detected by time-of-flight secondary ion mass spectrometry on the sulfate aerosols are fatty acids of different carbon chain length up to the C32 acid. These observations are consistent with literature accounts of functional group analysis of bulk samples, but this is the first direct evidence of fatty acid films on the surface of sulfate aerosols. Surface analysis leads to the conclusion that fatty acid films on continental aerosols may be more common than has been previously suggested.

  12. Optimized sparse-particle aerosol representations for modeling cloud-aerosol interactions

    NASA Astrophysics Data System (ADS)

    Fierce, Laura; McGraw, Robert

    2016-04-01

    Sparse representations of atmospheric aerosols are needed for efficient regional- and global-scale chemical transport models. Here we introduce a new framework for representing aerosol distributions, based on the method of moments. Given a set of moment constraints, we show how linear programming can be used to identify collections of sparse particles that approximately maximize distributional entropy. The collections of sparse particles derived from this approach reproduce CCN activity of the exact model aerosol distributions with high accuracy. Additionally, the linear programming techniques described in this study can be used to bound key aerosol properties, such as the number concentration of CCN. Unlike the commonly used sparse representations, such as modal and sectional schemes, the maximum-entropy moment-based approach is not constrained to pre-determined size bins or assumed distribution shapes. This study is a first step toward a new aerosol simulation scheme that will track multivariate aerosol distributions with sufficient computational efficiency for large-scale simulations.

  13. Organic Aerosol Nucleation and Growth at the CERN CLOUD chamber

    NASA Astrophysics Data System (ADS)

    Tröstl, Jasmin; Lethipalo, Katrianne; Bianchi, Federico; Sipilä, Mikko; Nieminen, Tuomo; Wagner, Robert; Frege, Carla; Simon, Mario; Weingartner, Ernest; Gysel, Martin; Dommen, Josef; Baltensperger, Urs

    2014-05-01

    It is well known that atmospheric aerosols influence the climate by changing Earth's radiation balance (IPCC 2007 and 2013). Recent models have shown (Merikanto et al. 2009) that aerosol nucleation is one of the biggest sources of low level cloud condensation nuclei. Still, aerosol nucleation and growth are not fully understood. The driving force of nucleation and growth is sulfuric acid. However ambient nucleation and growth rates cannot be explained by solely sulfuric acid as precursor. Recent studies have shown that only traces of precursors like ammonia and dimethylamine enhance the nucleation rates dramatically (Kirkby et al. 2011, Almeida et al., 2013). Thus the role of different aerosol precursor needs to be studied not only in ambient but also in very well controlled chamber experiments. The CLOUD (Cosmics Leaving OUtdoor Droplets) experiment enables conducting experiments very close to atmospheric conditions and with a very low contaminant background. The latest CLOUD experiments focus on the role of organics in aerosol nucleation and growth. For this purpose, numerous experiments with alpha-pinene have been conducted at the CERN CLOUD chamber. Several state-of-the-art instruments were used to cover the whole complexity of the experiment. Chamber conditions were set to 40% relative humidity and 5° C. Atmospheric concentrations of SO2, O3, HONO, H2O and alpha-pinene were injected to the chamber. Different oxidation conditions were used, yielding different levels of oxidized organics: (1) OH radicals, (2) Ozone with the OH scavenger H2 (pure ozonolysis) and (3) both. SO2 was injected to allow for sulfuric acid production. Optical UV fibers were used to enable photochemical reactions. A high field cage (30 kV) can be turned on to remove all charged particles in the chamber to enable completely neutral conditions. Comparing neutral conditions to the beam conditions using CERN's proton synchrotron, the fraction of ion-induced nucleation can be studied. Using

  14. MASS SPECTROMETRY OF INDIVIDUAL AEROSOL PARTICLES. (R823980)

    EPA Science Inventory

    Typically, in real-time aerosol mass spectrometry (RTAMS), individual airborne particles
    are ablated and ionized with a single focused laser pulse. This technique yields information that
    permits bulk characterization of the particle, but information about the particle's sur...

  15. Equilibrium absorptive partitioning theory between multiple aerosol particle modes

    NASA Astrophysics Data System (ADS)

    Crooks, Matthew; Connolly, Paul; Topping, David; McFiggans, Gordon

    2016-10-01

    An existing equilibrium absorptive partitioning model for calculating the equilibrium gas and particle concentrations of multiple semi-volatile organics within a bulk aerosol is extended to allow for multiple involatile aerosol modes of different sizes and chemical compositions. In the bulk aerosol problem, the partitioning coefficient determines the fraction of the total concentration of semi-volatile material that is in the condensed phase of the aerosol. This work modifies this definition for multiple polydisperse aerosol modes to account for multiple condensed concentrations, one for each semi-volatile on each involatile aerosol mode. The pivotal assumption in this work is that each aerosol mode contains an involatile constituent, thus overcoming the potential problem of smaller particles evaporating completely and then condensing on the larger particles to create a monodisperse aerosol at equilibrium. A parameterisation is proposed in which the coupled non-linear system of equations is approximated by a simpler set of equations obtained by setting the organic mole fraction in the partitioning coefficient to be the same across all modes. By perturbing the condensed masses about this approximate solution a correction term is derived that accounts for many of the removed complexities. This method offers a greatly increased efficiency in calculating the solution without significant loss in accuracy, thus making it suitable for inclusion in large-scale models.

  16. Thermophoretic separation of aerosol particles from a sampled gas stream

    DOEpatents

    Postma, Arlin K.

    1986-01-01

    A method for separating gaseous samples from a contained atmosphere that includes aerosol particles uses the step of repelling particles from a gas permeable surface or membrane by heating the surface to a temperature greater than that of the surrounding atmosphere. The resulting thermophoretic forces maintain the gas permeable surface clear of aerosol particles. The disclosed apparatus utilizes a downwardly facing heated plate of gas permeable material to combine thermophoretic repulsion and gravity forces to prevent particles of any size from contacting the separating plate surfaces.

  17. What Causes Aerosol Growth and Ozone Production in Smoke Plumes?

    NASA Astrophysics Data System (ADS)

    Alvarado, M. J.; Prinn, R. G.

    2006-12-01

    The growth of aerosol particles and production of ozone in smoke plumes is the result of a complex interaction between horizontal diffusion, gas-phase oxidation, coagulation, and mass transfer between phases. Models allow us to separate the effects of these processes and predict their impact on the global environment. We present the results of a new model of gas and aerosol chemistry applied to young biomass burning plumes. The model includes heterogeneous chemistry, kinetic mass transfer, coagulation and the formation of secondary organic and inorganic aerosol. Comparison with measurements from SAFARI 2000 (Hobbs et al., 2003, JGR, doi:10.1029/2002JD002352) suggests the baseline model underpredicts ozone formation and the growth of aerosol within the plume. We explore whether the model predictions can be improved by (1) including heterogeneous HONO production, and (2) adding in surrogates for the uncharacterized organic compounds emitted by the biomass burning. Including the heterogeneous reaction NO2 => HONO greatly improves the match for ozone, OH, and aerosol nitrate concentration, but only when the uptake coefficient approaches 10-3, which is over an order of magnitude higher than previously reported values (Stemmler et al., 2006, doi:10.1038/nature04603). Using the reaction NO2 => 0.5 HONO + 0.5 HNO3 with an uptake coefficient of 10-3 (the top of the range recommended by Jacob, 2000, Atm. Env.,34, 2131-2159) provides an even better match for aerosol nitrate, but produces less O3 and OH than the first reaction. Direct measurements of HONO and OH in young biomass plumes would help determine if this chemistry is taking place. We used two surrogates to model the uncharacterized compounds: long chain alkanes and monoterpenes, representing primary and secondary sources of condensable compounds respectively. Complete condensation of the long-chain alkanes can account for nearly all of the observed increase in organic carbon. However, the accommodation coefficient

  18. Carbonaceous aerosol particles from common vegetation in the Grand Canyon

    SciTech Connect

    Hallock, K.A.; Mazurek, M.A.; Cass, G.R.

    1992-05-01

    The problem of visibility reduction in the Grand Canyon due to fine organic aerosol particles in the atmosphere has become an area of increased environmental concern. Aerosol particles can be derived from many emission sources. In this report, we focus on identifying organic aerosols derived from common vegetation in the Grand Canyon. These aerosols are expected to be significant contributors to the total atmospheric organic aerosol content. Aerosol samples from living vegetation were collected by resuspension of surface wax and resin components liberated from the leaves of vegetation common to areas of the Grand Canyon. The samples were analyzed using high-resolution gas chromatography/mass spectrometry (GC/MS). Probable identification of compounds was made by comparison of sample spectra with National Institute of Standards and Technology (NIST) mass spectral references and positive identification of compounds was made when possible by comparison with authentic standards as well as NIST references. Using these references, we have been able to positively identify the presence of n-alkane and n-alkanoic acid homolog series in the surface waxes of the vegetation sampled. Several monoterpenes, sesquiterpenes, and diterpenes were identified also as possible biogenic aerosols which may contribute to the total organic aerosol abundance leading to visibility reduction in the Grand Canyon.

  19. Regional signatures in the organic composition of marine aerosol particles

    NASA Astrophysics Data System (ADS)

    Frossard, Amanda A.; Russell, Lynn M.; Keene, William C.; Kieber, David J.; Quinn, Patricia K.; Bates, Timothy S.

    2013-05-01

    Marine aerosol particles play an important role in the earth's radiative balance, yet the sources and composition of the organic fraction remain largely unconstrained. Recent measurements have been made in order to characterize the sources, composition, and concentration of aerosol particles in the marine boundary layer. The organic composition of submicron particles derived from multiple seawater regions have been measured using Fourier Transform Infrared (FTIR) spectroscopy. Cluster analysis of FTIR organic spectra suggest different spectral signatures based on collection location, seawater composition, and ambient conditions. Measurements including non-refractory aerosol composition from a high-resolution time of flight aerosol mass spectrometer (HR-ToF-AMS), seawater composition, and wind speed were used to interpret the cluster results, depending on the availability from each campaign. FTIR spectra of ambient particles are compared to FTIR spectra of primary marine particles generated from model ocean systems to infer the ambient particle production mechanisms and aging processes. Recent measurements used in the comparison include ambient and generated marine aerosol particles measured off the coast of California during CalNex in May and June 2010. Remote ambient marine aerosol particles were collected 100 miles off the coast of Monterey in the eastern Pacific during the EPEACE experiment in July 2011. Ambient and generated marine particles were measured in two different seawater types during WACS 2012 including colder, more productive water off the coast of the northeastern United States and warmer, oligotrophic water in the Sargasso Sea. These particles are also compared with those measured in the southeastern Pacific during VOCALS and the north Atlantic during ICEALOT.

  20. Simultaneous In-Situ Measurement of Local Particle Size, Particle Concentration, and Velocity of Aerosols.

    PubMed

    Weber; Schweiger

    1999-02-01

    Photon correlation spectroscopy has been applied to the characterization of (quasi-)monodisperse aerosols. The experiments were carried out with an experimental standard pin hole setup on laminar flowing aerosols of the submicrometer particle size range. It is shown that beside local mean particle size and local aerosol velocity simultaneously the local particle number concentration may be obtained from a single measured autocorrelation function. The proposed procedure does not require calibration. It is pointed out that measurement conditions can be adapted to the properties of the aerosol to be characterized, thus allowing characterization of aerosols over a wide parameter range, e.g., it is not restricted to the case of low particle concentration. The experimental results are compared to data from literature, data from reference measurements and data from a theoretical model, respectively. The method can also be usefull for characterization of other fluid-particle systems as hydrosols. Copyright 1999 Academic Press.

  1. A combined particle trap/HTDMA hygroscopicity study of mixed inorganic/organic aerosol particles

    NASA Astrophysics Data System (ADS)

    Zardini, A. A.; Sjogren, S.; Marcolli, C.; Krieger, U. K.; Gysel, M.; Weingartner, E.; Baltensperger, U.; Peter, T.

    2008-09-01

    Atmospheric aerosols are often mixtures of inorganic and organic material. Organics can represent a large fraction of the total aerosol mass and are comprised of water-soluble and insoluble compounds. Increasing attention was paid in the last decade to the capability of mixed inorganic/organic aerosol particles to take up water (hygroscopicity). We performed hygroscopicity measurements of internally mixed particles containing ammonium sulfate and carboxylic acids (citric, glutaric, adipic acid) in parallel with an electrodynamic balance (EDB) and a hygroscopicity tandem differential mobility analyzer (HTDMA). The organic compounds were chosen to represent three distinct physical states. During hygroscopicity cycles covering hydration and dehydration measured by the EDB and the HTDMA, pure citric acid remained always liquid, adipic acid remained always solid, while glutaric acid could be either. We show that the hygroscopicity of mixtures of the above compounds is well described by the Zdanovskii-Stokes-Robinson (ZSR) relationship as long as the two-component particle is completely liquid in the ammonium sulfate/glutaric acid system; deviations up to 10% in mass growth factor (corresponding to deviations up to 3.5% in size growth factor) are observed for the ammonium sulfate/citric acid 1:1 mixture at 80% RH. We observe even more significant discrepancies compared to what is expected from bulk thermodynamics when a solid component is present. We explain this in terms of a complex morphology resulting from the crystallization process leading to veins, pores, and grain boundaries which allow for water sorption in excess of bulk thermodynamic predictions caused by the inverse Kelvin effect on concave surfaces.

  2. Polarization resolved angular optical scattering of aerosol particles

    NASA Astrophysics Data System (ADS)

    Redding, B.; Pan, Y.; Wang, C.; Videen, G.; Cao, Hui

    2014-05-01

    Real-time detection and identification of bio-aerosol particles are crucial for the protection against chemical and biological agents. The strong elastic light scattering properties of airborne particles provides a natural means for rapid, non-invasive aerosol characterization. Recent theoretical predictions suggested that variations in the polarization dependent angular scattering cross section could provide an efficient means of classifying different airborne particles. In particular, the polarization dependent scattering cross section of aggregate particles is expected to depend on the shape of the primary particles. In order to experimentally validate this prediction, we built a high throughput, sampling system, capable of measuring the polarization resolved angular scattering cross section of individual aerosol particles flowing through an interrogating volume with a single shot of laser pulse. We calibrated the system by comparing the polarization dependent scattering cross section of individual polystyrene spheres with that predicted by Mie theory. We then used the system to study different particles types: Polystyrene aggregates composed 500 nm spheres and Bacillus subtilis (BG, Anthrax simulant) spores composed of elongated 500 nm × 1000 nm cylinder-line particles. We found that the polarization resolved scattering cross section depends on the shape of the constituent elements of the aggregates. This work indicates that the polarization resolved scattering cross section could be used for rapid discrimination between different bio-aerosol particles.

  3. Measurements of aerosol chemistry during new particle formation events at a remote rural mountain site.

    PubMed

    Creamean, Jessie M; Ault, Andrew P; Ten Hoeve, John E; Jacobson, Mark Z; Roberts, Gregory C; Prather, Kimberly A

    2011-10-01

    Determining the major sources of particles that act as cloud condensation nuclei (CCN) represents a critical step in the development of a more fundamental understanding of aerosol impacts on cloud formation and climate. Reported herein are direct measurements of the CCN activity of newly formed ambient particles, measured at a remote rural site in the Sierra Nevada Mountains of Northern California. Nucleation events in the winter of 2009 occurred during two pristine periods following precipitation, with higher gas-phase SO(2) concentrations during the second period, when faster particle growth occurred (7-8 nm/h). Amines, as opposed to ammonia, and sulfate were detected in the particle phase throughout new particle formation (NPF) events, increasing in number as the particles grew to larger sizes. Interestingly, long-range transport of SO(2) from Asia appeared to potentially play a role in NPF during faster particle growth. Understanding the propensity of newly formed particles to act as CCN is critical for predicting the effects of NPF on orographic cloud formation during winter storms along the Sierra Nevada Mountain range. The potential impact of newly formed particles in remote regions needs to be compared with that of transported urban aerosols when evaluating the impact of aerosols on clouds and climate.

  4. The on-line analysis of aerosol-delivered pharmaceuticals via single particle aerosol mass spectrometry.

    PubMed

    Morrical, Bradley D; Balaxi, Maria; Fergenson, David

    2015-07-15

    The use of single particle aerosol mass spectrometry (SPAMS) was evaluated for the analysis of inhaled pharmaceuticals to determine the mass distribution of the individual active pharmaceutical ingredients (API) in both single ingredient and combination drug products. SPAMS is an analytical technique where the individual aerodynamic diameters and chemical compositions of many aerosol particles are determined in real-time. The analysis was performed using a Livermore Instruments SPAMS 3.0, which allowed the efficient analysis of aerosol particles with broad size distributions and can acquire data even under a very large particle load. Data similar to what would normally require roughly three days of experimentation and analysis was collected in a five minute period and analyzed automatically. The results were computed to be comparable to those returned by a typical Next Generation Impactor (NGI) particle size distribution experiment.

  5. Ice Phase Transitions by Atmospheric Aerosol Particles of Varied Composition

    NASA Astrophysics Data System (ADS)

    DeMott, P. J.; Prenni, A. J.; Archuleta, C. A.; Kreidenweis, S. M.; Cziczo, D. J.; Murphy, D. M.; Thomson, D. S.

    2001-12-01

    This paper describes laboratory and field study measurements of water uptake and ice nucleation by surrogate and real atmospheric aerosol particles. Laboratory measurements of water uptake are made using a humidified tandem differential mobility analyzer (HTDMA) and a cloud condensation nucleus (CCN) instrument operating at 20 to 30 \\deg C. Measurements of ice nucleation are made using a continuous flow ice-thermal diffusion chamber (CFDC) operated to -60 \\deg C for relevance toward understanding cirrus cloud formation. Extending earlier laboratory studies of single composition aerosols, we are investigating water uptake and ice nucleation rates and mechanisms by mixed aerosols of various types, including sulfate-nitrate, sulfate-organic, mineral oxide-sulfate and black carbon-sulfate types. Methodologies will be described and results will be summarized. Field measurements are planned to study heterogeneous and homogeneous ice nucleation by free tropospheric aerosols at a high altitude laboratory. The field study will include measurements of the compositions of aerosols that activate ice formation by homogeneous and heterogeneous ice nucleation mechanisms. This aspect of the study will be facilitated by interfacing the CFDC to the PALMS (Particle Analysis by Laser Mass Spectrometry) instrument. This combined instrument system was tested in the laboratory to quantify sampling efficiencies and validate specificity for sampling ice nucleus aerosol particles. Initial field data, if available at conference time, will be compared and contrasted with the results obtained for laboratory surrogate particles.

  6. LASER DESORPTION IONIZATION OF ULTRAFINE AEROSOL PARTICLES. (R823980)

    EPA Science Inventory

    On-line analysis of ultrafine aerosol particle in the 12 to 150 nm size range is performed by
    laser desorption/ionization. Particles are size selected with a differential mobility analyzer and then
    sent into a linear time-of-flight mass spectrometer where they are ablated w...

  7. Discrimination and classification of bio-aerosol particles using optical spectroscopy and scattering

    NASA Astrophysics Data System (ADS)

    Eversole, Jay D.

    2011-03-01

    For more than a decade now, there has been significant emphasis for development of sensors of agent aerosols, especially for biological warfare (BW) agents. During this period, the Naval Research Laboratory (NRL) and other labs have explored the application of optical and spectroscopic methods relevant to biological composition discrimination to aerosol particle characterization. I will first briefly attempt to establish the connection between sensor performance metrics which are statistically determined, and aerosol particle measurements through the use of computational models, and also describe the challenge of ambient background characterization that would be needed to establish more reliable and deterministic sensor performance predictions. Greater attention will then be devoted to a discussion of basic particle properties and their measurement. The NRL effort has adopted an approach based on direct measurements on individual particles, principally of elastic scatter and laser-induced fluorescence (LIF), rather than populations of particles. The development of a LIF instrument using two sequential excitation wavelengths to detect fluorescence in discrete spectral bands will be described. Using this instrument, spectral characteristics of particles from a variety of biological materials including BW agent surrogates, as well as other ``calibration'' particles and some known ambient air constituents will be discussed in terms of the dependence of optical signatures on aerosol particle composition, size and incident laser fluence. Comparison of scattering and emission measurements from particles composed of widely different taxa, as well as from similar species under different growth conditions highlight the difficulties of establishing ground truth for complex biological material compositions. One aspect that is anticipated to provide greater insight to this type of particle classification capability is the development of a fundamental computational model of

  8. Intercomparison of number concentration measurements by various aerosol particle counters

    NASA Astrophysics Data System (ADS)

    Ankilov, A.; Baklanov, A.; Colhoun, M.; Enderle, K.-H.; Gras, J.; Julanov, Yu.; Kaller, D.; Lindner, A.; Lushnikov, A. A.; Mavliev, R.; McGovern, F.; Mirme, A.; O'Connor, T. C.; Podzimek, J.; Preining, O.; Reischl, G. P.; Rudolf, R.; Sem, G. J.; Szymanski, W. W.; Tamm, E.; Vrtala, A. E.; Wagner, P. E.; Winklmayr, W.; Zagaynov, V.

    Total aerosol particle number concentrations, as measured by means of 16 different measurement systems, have been quantitatively compared during an international workshop at the Institute for Experimental Physics of the University of Vienna, Austria, which was coordinated within the Committee on Nucleation and Atmospheric Aerosols (ICCP-IUGG). The range of measuring instruments includes Pollak counters (PCO) in use already for several decades, presently available commercial particle counters, as well as laboratory prototypes. The operation of the instruments considered was based on different measurement principles: (1) adiabatic expansion condensation particle counter, (2) flow diffusion condensation particle counter, (3) turbulent mixing condensation particle counter, (4) laser optical particle counter, and (5) electrostatic particle measurement system. Well-defined test aerosols with various chemical compositions were considered: DEHS, sodium chloride, silver, hydrocarbons, and tungsten oxide. The test aerosols were nearly monodispersed with mean particle diameters between 4 and 520 nm, the particle number concentrations were varied over a range from about 4×10 1 to 7×10 6 cm -3. A few measurements were performed with two-component aerosol mixtures. For simultaneous concentration measurements, the various instruments considered were operated under steady state conditions in a linear flow system. A series of at least 10 single concentration measurements was performed by each individual instrument at each set of test aerosol parameters. The average of the concentration data measured by the various instruments was defined as a common reference. The number concentrations obtained from the various instruments typically agreed within a factor of about two over the entire concentration range considered. The agreement of the measured concentrations is notable considering the various different measurement principles applied in this study, and particularly in view of the

  9. Water Uptake and Hygroscopic Growth of Organosulfate Aerosol.

    PubMed

    Estillore, Armando D; Hettiyadura, Anusha P S; Qin, Zhen; Leckrone, Erin; Wombacher, Becky; Humphry, Tim; Stone, Elizabeth A; Grassian, Vicki H

    2016-04-19

    Organosulfates (OS) are important components of secondary organic aerosol (SOA) that have been identified in numerous field studies. This class of compounds within SOA can potentially affect aerosol physicochemical properties such as hygroscopicity because of their polar and hydrophilic nature as well as their low volatility. Currently, there is a dearth of information on how aerosol particles that contain OS interact with water vapor in the atmosphere. Herein we report a laboratory investigation on the hygroscopic properties of a structurally diverse set of OS salts at varying relative humidity (RH) using a Hygroscopicity-Tandem Differential Mobility Analyzer (H-TDMA). The OS studied include the potassium salts of glycolic acid sulfate, hydroxyacetone sulfate, 4-hydroxy-2,3-epoxybutane sulfate, and 2-butenediol sulfate and the sodium salts of benzyl sulfate, methyl sulfate, ethyl sulfate, and propyl sulfate. In addition, mixtures of OS and sodium chloride were also studied. The results showed gradual deliquescence of these aerosol particles characterized by continuous uptake and evaporation of water in both hydration and dehydration processes for the OS, while the mixture showed prompt deliquescence and effloresce transitions, albeit at a lower relative humidity relative to pure sodium chloride. Hygroscopic growth of these OS at 85% RH were also fit to parameterized functional forms. This new information provided here has important implications about the atmospheric lifetime, light scattering properties, and the role of OS in cloud formation. Moreover, results of these studies can ultimately serve as a basis for the development and evaluation of thermodynamic models for these compounds in order to consider their impact on the atmosphere. PMID:26967467

  10. Hygroscopicity of aerosol particles and CCN activity of nearly hydrophobic particles in the urban atmosphere over Japan during summer

    NASA Astrophysics Data System (ADS)

    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.

  11. SAGE II aerosol validation - Selected altitude measurements, including particle micromeasurements

    NASA Technical Reports Server (NTRS)

    Oberbeck, Verne R.; Russell, Philip B.; Pueschel, Rudolf F.; Snetsinger, Kenneth G.; Ferry, Guy V.; Livingston, John M.; Rosen, James N.; Osborn, Mary T.; Kritz, Mark A.

    1989-01-01

    The validity of particulate extinction coefficients derived from limb path solar radiance measurements obtained during the Stratospheric Aerosol and Gas Experiment (SAGE) II is tested. The SAGE II measurements are compared with correlative aerosol measurements taken during January 1985, August 1985, and July 1986 with impactors, laser spectrometers, and filter samplers on a U-2 aircraft, an upward pointing lidar on a P-3 aircraft, and balloon-borne optical particle counters. The data for July 29, 1986 are discussed in detail. The aerosol measurements taken on this day at an altitude of 20.5 km produce particulate extinction values which validate the SAGE II values for similar wavelengths.

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

    PubMed

    Babu, S Suresh; Kompalli, Sobhan Kumar; Moorthy, K Krishna

    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 (~15-15,000nm) 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 <100nm) 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 167nm and 1150 to 1760nm 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

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

    PubMed

    Babu, S Suresh; Kompalli, Sobhan Kumar; Moorthy, K Krishna

    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 (~15-15,000nm) 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 <100nm) 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 167nm and 1150 to 1760nm 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

  14. Complete chemical analysis of aerosol particles in real-time

    SciTech Connect

    Yang, Mo; Reilly, P.T.A.; Gieray, R.A.; Whitten, W.B.; Ramsey, J.M.

    1996-12-31

    Real-time mass spectrometry of individual aerosol particles using an ion trap mass spectrometer is described. The microparticles are sampled directly from the air by a particle inlet system into the vacuum chamber. An incoming particle is detected as it passes through two CW laser beams and a pulsed laser is triggered to intercept the particle for laser ablation ionization at the center of the ion trap. The produced ions are analyzed by the ion trap mass spectrometer. Ions of interest are selected and dissociated through collision with buffer gas atoms for further fragmentation analysis. Real-time chemical analyses of inorganic, organic, and bacterial aerosol articles have been demonstrated. It has been confirmed that the velocity and the size of the incoming particles highly correlate to each other. The performance of the inlet system, particle detection, and preliminary results are discussed.

  15. Chemical characterization of aerosol particles by laser Raman spectroscopy. Revision

    SciTech Connect

    Fung, K.H.

    1999-12-01

    The importance of aerosol particles in many branches of science, such as atmospheric chemistry, combustion, interfacial science, and material processing, has been steadily growing during the past decades. One of the unique properties of these particles is the very high surface-to-volume ratios, thus making them readily serve as centers for gas-phase condensation and heterogeneous reactions. These particles must be characterized by size, shape, physical state, and chemical composition. Traditionally, optical elastic scattering has been applied to obtain the physical properties of these particle (e.g., particle size, size distribution, and particle density). These physical properties are particularly important in atmospheric science as they govern the distribution and transport of atmospheric aerosols.

  16. Reactions and mass spectra of complex particles using Aerosol CIMS

    NASA Astrophysics Data System (ADS)

    Hearn, John D.; Smith, Geoffrey D.

    2006-12-01

    Aerosol chemical ionization mass spectrometry (CIMS) is used both on- and off-line for the analysis of complex laboratory-generated and ambient particles. One of the primary advantages of Aerosol CIMS is the low degree of ion fragmentation, making this technique well suited for investigating the reactivity of complex particles. To demonstrate the usefulness of this "soft" ionization, particles generated from meat cooking were reacted with ozone and the composition was monitored as a function of reaction time. Two distinct kinetic regimes were observed with most of the oleic acid in these particles reacting quickly but with 30% appearing to be trapped in the complex mixture. Additionally, detection limits are measured to be sufficiently low (100-200 ng/m3) to detect some of the more abundant constituents in ambient particles, including sulfate, which is measured in real-time at 1.2 [mu]g/m3. To better characterize complex aerosols from a variety of sources, a novel off-line collection method was also developed in which non-volatile and semi-volatile organics are desorbed from particles and concentrated in a cold U-tube. Desorption from the U-tube followed by analysis with Aerosol CIMS revealed significant amounts of nicotine in cigarette smoke and levoglucosan in oak and pine smoke, suggesting that this may be a useful technique for monitoring particle tracer species. Additionally, secondary organic aerosol formed from the reaction of ozone with R-limonene and volatile organics from orange peel were analyzed off-line showing large molecular weight products (m/z > 300 amu) that may indicate the formation of oligomers. Finally, mass spectra of ambient aerosol collected offline reveal a complex mixture of what appears to be highly processed organics, some of which may contain nitrogen.

  17. Growth of nucleation mode particles in the summertime Arctic: a case study

    NASA Astrophysics Data System (ADS)

    Willis, Megan D.; Burkart, Julia; Thomas, Jennie L.; Köllner, Franziska; Schneider, Johannes; Bozem, Heiko; Hoor, Peter M.; Aliabadi, Amir A.; Schulz, Hannes; Herber, Andreas B.; Leaitch, W. Richard; Abbatt, Jonathan P. D.

    2016-06-01

    The summertime Arctic lower troposphere is a relatively pristine background aerosol environment dominated by nucleation and Aitken mode particles. Understanding the mechanisms that control the formation and growth of aerosol is crucial for our ability to predict cloud properties and therefore radiative balance and climate. We present an analysis of an aerosol growth event observed in the Canadian Arctic Archipelago during summer as part of the NETCARE project. Under stable and clean atmospheric conditions, with low inversion heights, carbon monoxide less than 80 ppbv, and black carbon less than 5 ng m-3, we observe growth of small particles, < 20 nm in diameter, into sizes above 50 nm. Aerosol growth was correlated with the presence of organic species, trimethylamine, and methanesulfonic acid (MSA) in particles ˜ 80 nm and larger, where the organics are similar to those previously observed in marine settings. MSA-to-sulfate ratios as high as 0.15 were observed during aerosol growth, suggesting an important marine influence. The organic-rich aerosol contributes significantly to particles active as cloud condensation nuclei (CCN, supersaturation = 0.6 %), which are elevated in concentration during aerosol growth above background levels of ˜ 100 to ˜ 220 cm-3. Results from this case study highlight the potential importance of secondary organic aerosol formation and its role in growing nucleation mode aerosol into CCN-active sizes in this remote marine environment.

  18. Influence of refractive index on the accuracy of size determination of aerosol particles with light-scattering aerosol counters.

    PubMed

    Quenzel, H

    1969-01-01

    The scattering properties of single aerosol particles with different indices of refraction have been computed from the Mie theory considering the spectral response of light-scattering aerosol counters commercially available. It is demonstrated that high resolution of the aerosol size distribution is impossible, particularly because of the different refractive indices of the atmospheric aerosol particles. By using other ranges of scattering angle for the measurement, one may, in some cases, obtain better results.

  19. Supercritical Fluid Extraction and Analysis of Tropospheric Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Hansen, Kristen J.

    An integrated sampling and supercritical fluid extraction (SFE) cell has been designed for whole-sample analysis of organic compounds on tropospheric aerosol particles. The low-volume extraction cell has been interfaced with a sampling manifold for aerosol particle collection in the field. After sample collection, the entire SFE cell was coupled to a gas chromatograph; after on-line extraction, the cryogenically -focused sample was separated and the volatile compounds detected with either a mass spectrometer or a flame ionization detector. A 20-minute extraction at 450 atm and 90 ^circC with pure supercritical CO _2 is sufficient for quantitative extraction of most volatile compounds in aerosol particle samples. A comparison between SFE and thermal desorption, the traditional whole-sample technique for analyses of this type, was performed using ambient aerosol particle samples, as well as samples containing known amounts of standard analytes. The results of these studies indicate that SFE of atmospheric aerosol particles provides quantitative measurement of several classes of organic compounds. SFE provides information that is complementary to that gained by the thermal desorption analysis. The results also indicate that SFE with CO _2 can be validated as an alternative to thermal desorption for quantitative recovery of several organic compounds. In 1989, the organic constituents of atmospheric aerosol particles collected at Niwot Ridge, Colorado, along with various physical and meteorological data, were measured during a collaborative field study. Temporal changes in the composition of samples collected during summertime at the rural site were studied. Thermal desorption-GC/FID was used to quantify selected compounds in samples collected during the field study. The statistical analysis of the 1989 Niwot Ridge data set is presented in this work. Principal component analysis was performed on thirty-one variables selected from the data set in order to ascertain

  20. Thermophoretic separation of aerosol particles from a sampled gas stream

    DOEpatents

    Postma, A.K.

    1984-09-07

    This disclosure relates to separation of aerosol particles from gas samples withdrawn from within a contained atmosphere, such as containment vessels for nuclear reactors or other process equipment where remote gaseous sampling is required. It is specifically directed to separation of dense aerosols including particles of any size and at high mass loadings and high corrosivity. The United States Government has rights in this invention pursuant to Contract DE-AC06-76FF02170 between the US Department of Energy and Westinghouse Electric Corporation.

  1. Particle Property Data Quality Flags for the MISR Aerosol Product

    NASA Astrophysics Data System (ADS)

    Gaitley, B. J.; Kahn, R. A.; Garay, M. J.

    2013-12-01

    , extending over more than twelve years of MISR data, aid in the assessment. Comparisons with the limited available AERONET aerosol type data are also made and evaluated as appropriate. Seasons and regions that regularly show poorly constrained aerosol type results are identified, as are times and places where particle property information can be used with confidence. This work is performed in part at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration and in part at the NASA Goddard Space Flight Center.

  2. FTIR Analysis of Functional Groups in Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Shokri, S. M.; McKenzie, G.; Dransfield, T. J.

    2012-12-01

    Secondary organic aerosols (SOA) are suspensions of particulate matter composed of compounds formed from chemical reactions of organic species in the atmosphere. Atmospheric particulate matter can have impacts on climate, the environment and human health. Standardized techniques to analyze the characteristics and composition of complex secondary organic aerosols are necessary to further investigate the formation of SOA and provide a better understanding of the reaction pathways of organic species in the atmosphere. While Aerosol Mass Spectrometry (AMS) can provide detailed information about the elemental composition of a sample, it reveals little about the chemical moieties which make up the particles. This work probes aerosol particles deposited on Teflon filters using FTIR, based on the protocols of Russell, et al. (Journal of Geophysical Research - Atmospheres, 114, 2009) and the spectral fitting algorithm of Takahama, et al (submitted, 2012). To validate the necessary calibration curves for the analysis of complex samples, primary aerosols of key compounds (e.g., citric acid, ammonium sulfate, sodium benzoate) were generated, and the accumulated masses of the aerosol samples were related to their IR absorption intensity. These validated calibration curves were then used to classify and quantify functional groups in SOA samples generated in chamber studies by MIT's Kroll group. The fitting algorithm currently quantifies the following functionalities: alcohols, alkanes, alkenes, amines, aromatics, carbonyls and carboxylic acids.

  3. Accelerated simulation of stochastic particle removal processes in particle-resolved aerosol models

    NASA Astrophysics Data System (ADS)

    Curtis, J. H.; Michelotti, M. D.; Riemer, N.; Heath, M. T.; West, M.

    2016-10-01

    Stochastic particle-resolved methods have proven useful for simulating multi-dimensional systems such as composition-resolved aerosol size distributions. While particle-resolved methods have substantial benefits for highly detailed simulations, these techniques suffer from high computational cost, motivating efforts to improve their algorithmic efficiency. Here we formulate an algorithm for accelerating particle removal processes by aggregating particles of similar size into bins. We present the Binned Algorithm for particle removal processes and analyze its performance with application to the atmospherically relevant process of aerosol dry deposition. We show that the Binned Algorithm can dramatically improve the efficiency of particle removals, particularly for low removal rates, and that computational cost is reduced without introducing additional error. In simulations of aerosol particle removal by dry deposition in atmospherically relevant conditions, we demonstrate about 50-times increase in algorithm efficiency.

  4. Unique DNA-barcoded aerosol test particles for studying aerosol transport

    DOE PAGES

    Harding, Ruth N.; Hara, Christine A.; Hall, Sara B.; Vitalis, Elizabeth A.; Thomas, Cynthia B.; Jones, A. Daniel; Day, James A.; Tur-Rojas, Vincent R.; Jorgensen, Trond; Herchert, Edwin; et al

    2016-03-22

    Data are presented for the first use of novel DNA-barcoded aerosol test particles that have been developed to track the fate of airborne contaminants in populated environments. Until DNATrax (DNA Tagged Reagents for Aerosol eXperiments) particles were developed, there was no way to rapidly validate air transport models with realistic particles in the respirable range of 1–10 μm in diameter. The DNATrax particles, developed at Lawrence Livermore National Laboratory (LLNL) and tested with the assistance of the Pentagon Force Protection Agency, are the first safe and effective materials for aerosol transport studies that are identified by DNA molecules. The usemore » of unique synthetic DNA barcodes overcomes the challenges of discerning the test material from pre-existing environmental or background contaminants (either naturally occurring or previously released). The DNATrax particle properties are demonstrated to have appropriate size range (approximately 1–4.5 μm in diameter) to accurately simulate bacterial spore transport. As a result, we describe details of the first field test of the DNATrax aerosol test particles in a large indoor facility.« less

  5. Selection of quasi-monodisperse super-micron aerosol particles

    NASA Astrophysics Data System (ADS)

    Rösch, Michael; Pfeifer, Sascha; Wiedensohler, Alfred; Stratmann, Frank

    2014-05-01

    Size-segregated quasi monodisperse particles are essential for e.g. fundamental research concerning cloud microphysical processes. Commonly a DMA (Differential Mobility Analyzer) is used to produce quasi-monodisperse submicron particles. Thereto first, polydisperse aerosol particles are bipolarly charged by a neutralizer, and then selected according to their electrical mobility with the DMA [Knutson et al. 1975]. Selecting a certain electrical mobility with a DMA results in a particle size distribution, which contains singly charged particles as well as undesired multiply charged larger particles. Often these larger particles need to either be removed from the generated aerosol or their signals have to be corrected for in the data inversion and interpretation process. This problem becomes even more serious when considering super-micron particles. Here we will present two different techniques for generating quasi-monodisperse super-micron aerosol particles with no or only an insignificant number of larger sized particles being present. First, we use a combination of a cyclone with adjustable aerodynamic cut-off diameter and our custom-built Maxi-DMA [Raddatz et al. 2013]. The cyclone removes particles larger than the desired ones prior to mobility selection with the DMA. This results in a reduction of the number of multiply charged particles of up to 99.8%. Second, we utilize a new combination of cyclone and PCVI (Pumped Counterflow Virtual Impactor), which is based on purely inertial separation and avoids particle charging. The PCVI instrument was previously described by Boulter et al. (2006) and Kulkarni et al. (2011). With our two setups we are able to produce quasi-monodisperse aerosol particles in the diameter range from 0.5 to 4.4 µm without a significant number of larger undesired particles being present. Acknowledgements: This work was done within the framework of the DFG funded Ice Nucleation research UnIT (INUIT, FOR 1525) under WE 4722/1-1. References

  6. Single particle atmospheric aerosol analysis using digital holographic microscopy

    NASA Astrophysics Data System (ADS)

    Mihailescu, Mona; Cojocaru, Ruxandra Elena; Kusko, C.; Toanca, Flori; Dinescu, A.; Schiopu, P.

    2011-06-01

    The aim of this research is to calculate the refractive index of transparent atmospheric aerosols, which have biological origin, using a digital holographic microscopy technique (DHM). The samples are collected on filters, using miniature impactors for particles with dimensions smaller than 10μm (on even one axis), from a height of over 20 meters, in Magurele, a rural location near the urban and industrial agglomeration of the capital city, Bucharest. Due to their organic or inorganic origin, each atmospheric aerosol particle has different size, shape and optical properties which have a determinant role in LIDAR measurements. We record on a CCD camera hundreds of holograms which contain the diffraction pattern from every aerosol particle superposed with the reference wave. Digitally, we scan the entire volume of one particle with nanometric resolution (using an algorithm based on the Fresnel approximation). The calibration was done using an object with known dimensions fabricated by e-beam lithography and some complementary measurements were done in confocal microscopy. Our analysis separates four main classes of atmospheric aerosols particles (wires, columns, spherical fragments, and irregular). The predominant class in the investigated period is the first one, which has biological origin and the refractive index was calculated starting from the phase shift introduced by them in the optical path and models for their cylindrical shape. The influence of spatial filtering in the reconstructed object images was investigated.

  7. Time Resolved Measurements of Primary Biogenic Aerosol Particles in Amazonia

    NASA Astrophysics Data System (ADS)

    Wollny, A. G.; Garland, R.; Pöschl, U.

    2009-04-01

    Biogenic aerosols are ubiquitous in the Earth's atmosphere and they influence atmospheric chemistry and physics, the biosphere, climate, and public health. They play an important role in the spread of biological organisms and reproductive materials, and they can cause or enhance human, animal, and plant diseases. Moreover, they influence the Earth's energy budget by scattering and absorbing radiation, and they can initiate the formation of clouds and precipitation as cloud condensation and ice nuclei. The composition, abundance, and origin of biogenic aerosol particles and components are, however, still not well understood and poorly quantified. Prominent examples of primary biogenic aerosol particles, which are directly emitted from the biosphere to the atmosphere, are pollen, bacteria, fungal spores, viruses, and fragments of animals and plants. During the Amazonian Aerosol Characterization Experiment (AMAZE-08) a large number of aerosol and gas-phase measurements were taken on a remote site close to Manaus, Brazil, during a period of five weeks in February and March 2008. This presented study is focused on data from an ultraviolet aerodynamic particle sizer (UVAPS, TSI inc.) that has been deployed for the first time in Amazonia. In this instrument, particle counting and aerodynamic sizing over the range of 0.5-20 µm are complemented by the measurement of UV fluorescence at 355 nm (excitation) and 420-575 nm (emission), respectively. Fluorescence at these wavelengths is characteristic for reduced pyridine nucleotides (e.g., NAD(P)H) and for riboflavin, which are specific for living cells. Thus particles exhibiting fluorescence signals can be regarded as "viable aerosols" or "fluorescent bioparticles" (FBAP), and their concentration can be considered as lower limit for the actual abundance of primary biogenic aerosol particles. Data from the UVAPS were averaged over 5 minute time intervals. The presence of bioparticles in the observed size range has been

  8. Lake Spray Aerosol: A Chemical Signature from Individual Ambient Particles.

    PubMed

    Axson, Jessica L; May, Nathaniel W; Colón-Bernal, Isabel D; Pratt, Kerri A; Ault, Andrew P

    2016-09-20

    Aerosol production from wave breaking on freshwater lakes, including the Laurentian Great Lakes, is poorly understood in comparison to sea spray aerosol (SSA). Aerosols from freshwater have the potential to impact regional climate and public health. Herein, lake spray aerosol (LSA) is defined as aerosol generated from freshwater through bubble bursting, analogous to SSA from seawater. A chemical signature for LSA was determined from measurements of ambient particles collected on the southeastern shore of Lake Michigan during an event (July 6-8, 2015) with wave heights up to 3.1 m. For comparison, surface freshwater was collected, and LSA were generated in the laboratory. Single particle microscopy and mass spectrometry analysis of field and laboratory-generated samples show that LSA particles are primarily calcium (carbonate) with lower concentrations of other inorganic ions and organic material. Laboratory number size distributions show ultrafine and accumulation modes at 53 (±1) and 276 (±8) nm, respectively. This study provides the first chemical signature for LSA. LSA composition is shown to be coupled to Great Lakes water chemistry (Ca(2+) > Mg(2+) > Na(+) > K(+)) and distinct from SSA. Understanding LSA physicochemical properties will improve assessment of LSA impacts on regional air quality, climate, and health. PMID:27548099

  9. Lake Spray Aerosol: A Chemical Signature from Individual Ambient Particles.

    PubMed

    Axson, Jessica L; May, Nathaniel W; Colón-Bernal, Isabel D; Pratt, Kerri A; Ault, Andrew P

    2016-09-20

    Aerosol production from wave breaking on freshwater lakes, including the Laurentian Great Lakes, is poorly understood in comparison to sea spray aerosol (SSA). Aerosols from freshwater have the potential to impact regional climate and public health. Herein, lake spray aerosol (LSA) is defined as aerosol generated from freshwater through bubble bursting, analogous to SSA from seawater. A chemical signature for LSA was determined from measurements of ambient particles collected on the southeastern shore of Lake Michigan during an event (July 6-8, 2015) with wave heights up to 3.1 m. For comparison, surface freshwater was collected, and LSA were generated in the laboratory. Single particle microscopy and mass spectrometry analysis of field and laboratory-generated samples show that LSA particles are primarily calcium (carbonate) with lower concentrations of other inorganic ions and organic material. Laboratory number size distributions show ultrafine and accumulation modes at 53 (±1) and 276 (±8) nm, respectively. This study provides the first chemical signature for LSA. LSA composition is shown to be coupled to Great Lakes water chemistry (Ca(2+) > Mg(2+) > Na(+) > K(+)) and distinct from SSA. Understanding LSA physicochemical properties will improve assessment of LSA impacts on regional air quality, climate, and health.

  10. Hygroscopic Measurements of Aerosol Particles in Colorado during the Discover AQ Campaign 2014

    NASA Astrophysics Data System (ADS)

    Orozco, D.; Delgado, R.; Espinosa, R.; Martins, J. V.; Hoff, R. M.

    2014-12-01

    In ambient conditions, aerosol particles experience hygroscopic growth due to the influence of relative humidity (RH), scattering more light than when the particles are dry. The quantitative knowledge of the RH effect and its influence on the light scattering and, in particular, on the phase function and polarization of aerosol particles is of substantial importance when comparing ground observations with other optical aerosol measurements such satellite and sunphotometric retrievals of aerosol optical depth and their inversions. In the summer of 2014, the DISCOVER-AQ campaign was held in Colorado, where systematic and concurrent observations of column- integrated surface, and vertically-resolved distributions of aerosols and trace gases relevant to air quality and their evolution during the day were observed. Aerosol optical properties were measured in the UMBC trailer at the city of Golden using a TSI-3563 nephelometer and an in-situ Polarized Imaging Nephelometer (PI-NEPH) designed and built by the LACO group at UMBC. The PI-NEPH measures aerosol phase matrix components in high angular range between 2 and 178 degrees scattering angle at three wavelengths (λ=473, 532 and 671nm). The two measured elements of the phase matrix, intensity (P11) and linear polarization (P12) provide extensive characterization of the scattering properties of the studied aerosol. The scattering coefficient, P11 and P12 were measured under different humidity conditions to obtain the enhancement factor f(RH) and the dependence of P11 and P12 to RH using a humidifier dryer system covering a RH range from 20 to 90%. The ratio between scattering coefficients at high and low humidity in Golden Colorado showed relatively low hygroscopic growth in the aerosol particles f(RH=80%) was 1.27±0.19 for the first three weeks of sampling. According to speciated measurements performed at the UMBC trailer, the predominance of dust and organic aerosols over more hygroscopic nitrate and sulfate in the

  11. Mixing properties of individual submicrometer aerosol particles in Vienna

    NASA Astrophysics Data System (ADS)

    Okada, Kikuo; Hitzenberger, Regina M.

    Individual aerosol particles were collected on 5 days with different meteorological conditions in March, April and June 1991 in the urban atmosphere of Vienna in Austria. The samples collected with an impactor were examined by electron microscopy. The mixing properties of submicrometer aerosol particles with radii between 0.1 and 1 μm were studied by using the dialysis (extraction) of water-soluble material. The averaged results showed that more than 85% of particles with radii between 0.1 and 0.7 μm were hygroscopic. However, more than 50% of particles with radii larger than 0.2 μm were mixed particles (hygroscopic particles with water-insoluble inclusions), and they were dominant (80%) in the size range 0.5-0.7 μm radius. The results also showed that the number proportion of mixed particles increased with increasing radius and the abundance increased with increasing particle loading in the atmosphere. The volume fraction of water-soluble material ( ɛ) in mixed particles tended to decrease with increasing radius, implying the formation of mixed particles by heterogeneous processes such as condensation and/or surface reaction. Some results of elemental composition in individual particles analyzed with an energy-dispersive X-ray (EDX) analyzer equipped with an electron microscope are also presented in this paper.

  12. Novel Measurements of Aerosol Particle Interfaces Using Biphasic Microfluidics

    NASA Astrophysics Data System (ADS)

    Metcalf, A. R.; Dutcher, C. S.

    2014-12-01

    Secondary organic aerosol (SOA) particles are nearly ubiquitous in the atmosphere and yet there remains large uncertainties in their formation processes and ambient properties. These particles are complex microenvironments, which can contain multiple interfaces due to internal aqueous-organic phase partitioning and to the external liquid-vapor surface. These aerosol interfaces can profoundly affect the fate of condensable organic compounds emitted into the atmosphere by altering the way in which organic vapors interact with the ambient aerosol. Aerosol interfaces affect particle internal structure, species uptake, equilibrium partitioning, activation to cloud condensation or ice nuclei, and optical properties. For example, organic thin films can shield the core of the aerosol from the ambient environment, which may disrupt equilibrium partitioning and mass transfer. To improve our ability to accurately predict the fate of SOA in the atmosphere, we must improve our knowledge of aerosol interfaces and their interactions with the ambient environment. Few technologies exist to accurately probe aerosol interfaces at atmospherically-relevant conditions. In this talk, a novel method using biphasic microscale flows will be introduced for generating, trapping, and perturbing complex interfaces at atmospherically relevant conditions. These microfluidic experiments utilize high-speed imaging to monitor interfacial phenomena at the microscale and are performed with phase contrast and fluorescence microscopy on a temperature-controlled inverted microscope stage. From these experiments, interfacial thermodynamic properties such as surface tension, rheological properties such as interfacial moduli, and kinetic properties such as mass transfer coefficients can be measured or inferred. Chemical compositions of the liquid phases studied here span a range of viscosities and include electrolyte and water soluble organic acid species often observed in the atmosphere, such as mixtures

  13. Nonequilibrium Atmospheric Secondary Organic Aerosol Formation and Growth

    SciTech Connect

    Perraud, Veronique M.; Bruns, Emily A.; Ezell, Michael J.; Johnson, Stanley N.; Yu, Yong; Alexander, M. L.; Zelenyuk, Alla; Imre, D.; Chang, W. L.; Dabdub, Donald; Pankow, James F.; Finlayson-Pitts, Barbara J.

    2012-02-21

    Airborne particles play a critical role in air quality, human health effects, visibility and climate. Secondary organic aerosols (SOA) account for a significant portion of total airborne particles. They are formed in reactions of organic gases that produce low volatility and semi-volatile organic compounds (SVOCs). Current atmospheric models assume that SOA are liquids into which SVOCs undergo equilibrium partitioning and grow the particles. However a large discrepancy between model predictions and field measurements of SOA is commonly observed. We report here laboratory studies of the oxidation of a-pinene by ozone and nitrate radicals and show that particle composition is actually consistent with a kinetically determined growth mechanism, and not with equilibrium partitioning between the gas phase and liquid particles. If this is indeed a general phenomenon in air, the formulation of atmospheric SOA models will have to be revised to reflect this new paradigm. This will have significant impacts on quantifying the role of SOA in air quality, visibility, and climate.

  14. Condensational growth and trace species scavenging in stratospheric sulfuric acid/water aerosol droplets

    NASA Technical Reports Server (NTRS)

    Tompson, Robert V., Jr.

    1991-01-01

    Stratospheric aerosols play a significant role in the environment. The composition of aerosols is believed to be a liquid solution of sulfuric acid and water with numerous trace species. Of these trace species, ozone in particular was recognized as being very important in its role of shielding the environment from harmful ultraviolet radiation. Also among the trace species are HCl and ClONO2, the so called chlorine reservoir species and various oxides of nitrogen. The quantity of stratospheric aerosol and its particle size distribution determines, to a large degree, the chemistry present in the stratosphere. Aerosols experience 3 types of growth: nucleation, condensation, and coagulation. The application of condensation investigations to the specific problem of stratospheric aerosols is discussed.

  15. Processing of aerosol particles within the Habshan pollution plume

    NASA Astrophysics Data System (ADS)

    Semeniuk, T. A.; Bruintjes, R.; Salazar, V.; Breed, D.; Jensen, T.; Buseck, P. R.

    2015-03-01

    The Habshan industrial site in the United Arab Emirates produces a regional-scale pollution plume associated with oil and gas processing, discharging high loadings of sulfates and chlorides into the atmosphere, which interact with the ambient aerosol population. Aerosol particles and trace gas chemistry at this site were studied on two flights in the summer of 2002. Measurements were collected along vertical plume profiles to show changes associated with atmospheric processing of particle and gas components. Close to the outlet stack, particle concentrations were over 10,000 cm-3, dropping to <2000 cm-3 in more dilute plume around 1500 m above the stack. Particles collected close to the stack and within the dilute plume were individually measured for size, morphology, composition, and mixing state using transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy. Close to the stack, most coarse particles consisted of mineral dust and NaCl crystals from burning oil brines, while sulfate droplets dominated the fine mode. In more dilute plume, at least 1500 m above the stack, the particle spectrum was more diverse, with a significant increase in internally mixed particle types. Dilute plume samples consisted of coarse NaCl/silicate aggregates or NaCl-rich droplets, often with a sulfate component, while fine-fraction particles were of mixed cation sulfates, also internally mixed with nanospherical soot or silicates. Thus, both chloride and sulfate components of the pollution plume rapidly reacted with ambient mineral dust to form coated and aggregate particles, enhancing particle size, hygroscopicity, and reactivity of the coarse mode. The fine-fraction sulfate-bearing particles formed in the plume contribute to regional transport of sulfates, while coarse sulfate-bearing fractions locally reduced the SO2 loading through sedimentation. The chloride- and sulfate-bearing internally mixed particles formed in the plume markedly changed the

  16. Organic aerosol mixing observed by single-particle mass spectrometry.

    PubMed

    Robinson, Ellis Shipley; Saleh, Rawad; Donahue, Neil M

    2013-12-27

    We present direct measurements of mixing between separately prepared organic aerosol populations in a smog chamber using single-particle mass spectra from the high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). Docosane and docosane-d46 (22 carbon linear solid alkane) did not show any signs of mixing, but squalane and squalane-d62 (30 carbon branched liquid alkane) mixed on the time scale expected from a condensational-mixing model. Docosane and docosane-d46 were driven to mix when the chamber temperature was elevated above the melting point for docosane. Docosane vapors were shown to mix into squalane-d62, but not the other way around. These results are consistent with low diffusivity in the solid phase of docosane particles. We performed mixing experiments on secondary organic aerosol (SOA) surrogate systems finding that SOA derived from toluene-d8 (a surrogate for anthropogenic SOA (aSOA)) does not mix into squalane (a surrogate for hydrophobic primary organic aerosol (POA)) but does mix into SOA derived from α-pinene (biogenic SOA (bSOA) surrogate). For the aSOA/POA, the volatility of either aerosol does not limit gas-phase diffusion, indicating that the two particle populations do not mix simply because they are immiscible. In the aSOA/bSOA system, the presence of toluene-d8-derived SOA molecules in the α-pinene-derived SOA provides evidence that the diffusion coefficient in α-pinene-derived SOA is high enough for mixing on the time scale of 1 min. The observations from all of these mixing experiments are generally invisible to bulk aerosol composition measurements but are made possible with single-particle composition data.

  17. Impeded ice nucleation in glassy and highly viscous aerosol particles: the role of water diffusion

    NASA Astrophysics Data System (ADS)

    Marcolli, C.; Peter, T.; Zobrist, B.; Krieger, U. K.; Luo, B. P.; Soonsin, V.; Pedernera, D. A.; Koop, T.

    2010-05-01

    In situ and remote observations in the upper troposphere have disclosed the existence of water vapor pressures up to and even above water saturation. Under such conditions ice particle formation by homogeneous nucleation is expected to set in followed by ice crystal growth until the supersaturation is consumed. While the highest measured water vapor values might not withstand rigorous quality checks, values up to water saturation seem to be occurring. Since air masses appear to contain sufficient numbers of aerosol particles for cloud formation, the question arises why these aerosols are not successful at nucleating ice. The atmospheric aerosol is a complex mixture of various inorganic and organic components, whereas the organic fraction can represent more than 50% of the total aerosol mass. The homogeneous ice nucleation threshold was established for atmospherically relevant salt solutions and sulfuric acid, but only for a few organic species. The organic aerosol fraction tends to remain liquid instead of crystallizing as the temperature is decreased and, thus, organic aerosol particles may form highly viscous liquids. When the viscosity of such liquids reaches values in the order of 1012 Pa s, the molecular motion becomes so slow, that the sample vitrifies at the glass transition temperature Tg. If aerosol particles were present as glasses, this would influence several physical and chemical processes in the atmosphere significantly: Water uptake from the gas phase would be drastically impeded and ice nucleation inhibited. We investigated the glass transition temperature of a series of aqueous organic solutions such as polyols, sugars and dicarboxylic acids as a function of the solute concentration using a differential scanning calorimeter (DSC). These measurements show that the higher the molar mass of the organic solutes, the higher Tg of their respective solutions at a given water activity. Aerosol particles containing larger (≥150 g mol-1) organic molecules

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Light Absorption of Biogenic Aerosol Particles in Amazonia

    NASA Astrophysics Data System (ADS)

    Holanda, B. A.; Artaxo, P.; Ferreira De Brito, J.; Barbosa, H. M.; Andreae, M. O.; Saturno, J.; Pöhlker, C.; Holben, B. N.; Schafer, J.

    2014-12-01

    Aerosol absorption is a key issue in proper calculation of aerosol radiative forcing. Especially in the tropics with the dominance of natural biogenic aerosol and brown carbon, the so called anomalous absorption is of particular interest. A special experiment was designed to study the wavelength dependence of aerosol absorption for PM2.5 as well as for PM10 particles in the wet season in Central Amazonia. Aerosol analysis occurred from May to August 2014, in the ZF2 ecological reservation, situated at about 55 km North of Manaus in very pristine conditions Two 7 wavelengths AE33 Aethalometers were deployed measuring in parallel, but with a PM2.5 and PM10 inlets. Two MAAP (Multiangle Aerosol Absorption Photometer) were operated in parallel with the AE33 exactly at the same PM2.5 and PM10 inlets. Organic and elemental carbon was analyzed using collection with quartz filters and analysis using a Sunset OC/EC analyzer. Aerosol light scattering for 3 wavelengths was measured using Air Photon and TSI Nephelometers. Aerosol size distribution was measured with one TSI SMPS and a GRIMM OPC to have the size range from 10 nm to 10 micrometers. Particles were measured under dry conditions using diffusion dryers. Aerosol optical depth and absorption was also measured with an AERONET sunphotometer operated close to the site. As the experiment was run in the wet season, very low equivalent black carbon (EBC) were measured, with average concentrations around 50 ng/m³ during May, increasing to 130 ng/m³ in June and July. The measurements adjusted for similar wavelengths shows excellent agreement between the MAAP and AE33 for both inlets (PM2.5 and PM10). It was not possible statistically infer absorption from the coarse mode biogenic particles, since the absorption was completely dominated by fine mode particles. AERONET measurements shows very low values of AOD, at 0.17 at 500 nm and 0.13 at 870 nm, with very low absorption AOD values at 0.00086 at 676 nm and 0.0068 at 872 nm

  20. Influence of particle-phase state on the hygroscopic behavior of mixed organic-inorganic aerosols

    NASA Astrophysics Data System (ADS)

    Hodas, N.; Zuend, A.; Mui, W.; Flagan, R. C.; Seinfeld, J. H.

    2015-05-01

    Recent work has demonstrated that organic and mixed organic-inorganic particles can exhibit multiple phase states depending on their chemical composition and on ambient conditions such as relative humidity (RH). To explore the extent to which water uptake varies with particle-phase behavior, hygroscopic growth factors (HGFs) of nine laboratory-generated, organic and organic-inorganic aerosol systems with physical states ranging from well-mixed liquids to phase-separated particles to viscous liquids or semi-solids were measured with the Differential Aerosol Sizing and Hygroscopicity Spectrometer Probe at RH values ranging from 40 to 90%. Water-uptake measurements were accompanied by HGF and RH-dependent thermodynamic equilibrium calculations using the Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model. In addition, AIOMFAC-predicted growth curves are compared to several simplified HGF modeling approaches: (1) representing particles as ideal, well-mixed liquids; (2) forcing a single phase but accounting for non-ideal interactions through activity coefficient calculations; and (3) a Zdanovskii-Stokes-Robinson-like calculation in which complete separation of the inorganic and organic components is assumed at all RH values, with water uptake treated separately in each of the individual phases. We observed variability in the characteristics of measured hygroscopic growth curves across aerosol systems with differing phase behaviors, with growth curves approaching smoother, more continuous water uptake with decreasing prevalence of liquid-liquid phase separation and increasing oxygen : carbon ratios of the organic aerosol components. We also observed indirect evidence for the dehydration-induced formation of highly viscous semi-solid phases and for kinetic limitations to the crystallization of ammonium sulfate at low RH for sucrose-containing particles. AIOMFAC-predicted growth curves are generally in good agreement with the HGF

  1. Influence of particle phase state on the hygroscopic behavior of mixed organic-inorganic aerosols

    NASA Astrophysics Data System (ADS)

    Hodas, N.; Zuend, A.; Mui, W.; Flagan, R. C.; Seinfeld, J. H.

    2014-12-01

    Recent work has demonstrated that organic and mixed organic-inorganic particles can exhibit multiple phase states depending on their chemical composition and on ambient conditions such as relative humidity (RH). To explore the extent to which water uptake varies with particle phase behavior, hygroscopic growth factors (HGFs) of nine laboratory-generated, organic and organic-inorganic aerosol systems with physical states ranging from well-mixed liquids, to phase-separated particles, to viscous liquids or semi-solids were measured with the Differential Aerosol Sizing and Hygroscopicity Spectrometer Probe at RH values ranging from 40-90%. Water-uptake measurements were accompanied by HGF and RH-dependent thermodynamic equilibrium calculations using the Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model. In addition, AIOMFAC-predicted growth curves are compared to several simplified HGF modeling approaches: (1) representing particles as ideal, well-mixed liquids, (2) forcing a single phase, but accounting for non-ideal interactions through activity coefficient calculations, and (3) a Zdanovskii-Stokes-Robinson-like calculation in which complete separation between the inorganic and organic components is assumed at all RH values, with water-uptake treated separately in each of the individual phases. We observed variability in the characteristics of measured hygroscopic growth curves across aerosol systems with differing phase behaviors, with growth curves approaching smoother, more continuous water uptake with decreasing prevalence of liquid-liquid phase separation and increasing oxygen : carbon ratios of the organic aerosol components. We also observed indirect evidence for the dehydration-induced formation of highly viscous semi-solid phases and for kinetic limitations to the crystallization of ammonium sulfate at low RH for sucrose-containing particles. AIOMFAC-predicted growth curves are generally in good agreement with the HGF

  2. Dominant Aerosol Particle Type/Mixture Identification at Worldwide Locations Using the Aerosol Robotic Network (AERONET)

    NASA Astrophysics Data System (ADS)

    Giles, D. M.; Holben, B.; Eck, T. F.; Sinyuk, A.; Smirnov, A.; Slutsker, I.; Dickerson, R. R.; Thompson, A. M.; Schafer, J. S.

    2011-12-01

    Aerosol absorption results in atmospheric heating for various forms of particulate matter - we address means of partitioning mineral dust, pollution (e.g., black and brown carbon), and mixtures of the two using remote sensing techniques. Remotely sensed spectral aerosol optical depth (AOD) and single scattering albedo (SSA) derived from Aerosol Robotic Network (AERONET) sun photometer measurements can be used to calculate the absorption aerosol optical depth (AAOD) at 440, 675, and 870 nm. The spectral change in AAOD with wavelength on logarithmic scales provides the absorption Angstrom exponent (AAE). Recently, a few studies have shown that the relationship between aerosol absorption (i.e., AAE or SSA) and aerosol size [i.e., Angstrom exponent (AE) or fine mode fraction (FMF) of the AOD] can estimate the dominant aerosol particle types/mixtures (i.e., dust, pollution, and dust and pollution mixtures) [Bergstrom et al., 2007; Russell et al., 2010; Lee et al. 2010; Giles et al., 2011]. To evaluate these methods, approximately 20 AERONET sites were grouped into various aerosol categories (i.e., dust, mixed, urban/industrial, and biomass burning) based on aerosol types/mixtures identified in previous studies. For data collected between 1999 and 2010, the long-term data set was analyzed to determine the magnitude of spectral AAOD, perform a sensitivity study on AAE by varying the spectral AOD and SSA, and identify dominant aerosol particle types/mixtures. An assessment of the spectral AAOD showed, on average, that the mixed (dust and pollution) category had the highest absorption (AAE ~1.5) followed by biomass burning (AAE~1.3), dust (AAE~1.7), and urban/industrial (AAE~1.2) categories with AAOD (440 nm) varying between 0.03 and 0.09 among these categories. Perturbing input parameters based on the expected uncertainties for AOD (±0.01) and SSA [±0.03; for cases where AOD(440 nm)>0.4], the sensitivity study showed the perturbed AAE mean varied from the unperturbed

  3. RELATIONSHIP BETWEEN MEASURED WATER VAPOR GROWTH AND CHEMISTRY OF ATMOSPHERIC AEROSOL FOR GRAND CANYON, ARIZONA, IN WINTER 1990.

    EPA Science Inventory

    Size-resolved aerosol growth measurements (growth = moist particle diameter/dry particle diameter) and chemical composition monitoring were conducted during a 3 month period in the winter of 1990 at the South Rim of Grand Canyon National Park, AZ as part of the Navajo Generating ...

  4. A numerical simulation of atmospheric photochemical processes including interactions with aerosol particles

    SciTech Connect

    Hackler, M.A.

    1989-01-01

    We propose a comprehensive model of atmospheric photochemical processes that can be used to investigate the interactions between gas species and aerosol particles. We considered both gas and particle phase reactions, transport of material between these phases, convection, turbulent diffusion, particle growth, coagulation, nucleation, and sources. The aerosol particle phase is not forced to follow the gas phase in equilibrium; transport to the particles is described by diffusion to the particle surface. The resulting model treats 33 gas phase species and 39 particles phase species; 16 of these are transported between the phases. The particle size distribution is approximated by 9 sections between 0.01 and 10 {mu}m diameter. Strong interactions between the gas and particles are seen. Higher relative humidity results in more particle volume and surface area, allowing the interphase transport to become competitive with the reaction terms. In particular, at high relative humidities the increased scavenging of HO{sub 2} radicals by particles reduces the O{sub 3} maximum concentration. This effect is seen only on days when the maximum relative humidity exceeds 90%. This conclusion has implications for the applicability of models developed for the Los Angeles Basin, where the maximum relative humidity rarely exceeds 75%, to more humid climates like Houston.

  5. Ice Nucleation Activity of Various Agricultural Soil Dust Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Schiebel, Thea; Höhler, Kristina; Funk, Roger; Hill, Thomas C. J.; Levin, Ezra J. T.; Nadolny, Jens; Steinke, Isabelle; Suski, Kaitlyn J.; Ullrich, Romy; Wagner, Robert; Weber, Ines; DeMott, Paul J.; Möhler, Ottmar

    2016-04-01

    Recent investigations at the cloud simulation chamber AIDA (Aerosol Interactions and Dynamics in the Atmosphere) suggest that agricultural soil dust has an ice nucleation ability that is enhanced up to a factor of 10 compared to desert dust, especially at temperatures above -26 °C (Steinke et al., in preparation for submission). This enhancement might be caused by the contribution of very ice-active biological particles. In addition, soil dust aerosol particles often contain a considerably higher amount of organic matter compared to desert dust particles. To test agricultural soil dust as a source of ice nucleating particles, especially for ice formation in warm clouds, we conducted a series of laboratory measurements with different soil dust samples to extend the existing AIDA dataset. The AIDA has a volume of 84 m3 and operates under atmospherically relevant conditions over wide ranges of temperature, pressure and humidity. By controlled adiabatic expansions, the ascent of an air parcel in the troposphere can be simulated. As a supplement to the AIDA facility, we use the INKA (Ice Nucleation Instrument of the KArlsruhe Institute of Technology) continuous flow diffusion chamber based on the design by Rogers (1988) to expose the sampled aerosol particles to a continuously increasing saturation ratio by keeping the aerosol temperature constant. For our experiments, soil dust was dry dispersed into the AIDA vessel. First, fast saturation ratio scans at different temperatures were performed with INKA, sampling soil dust aerosol particles directly from the AIDA vessel. Then, we conducted the AIDA expansion experiment starting at a preset temperature. The combination of these two different methods provides a robust data set on the temperature-dependent ice activity of various agriculture soil dust aerosol particles with a special focus on relatively high temperatures. In addition, to extend the data set, we investigated the role of biological and organic matter in more

  6. Water uptake of clay and desert dust aerosol particles at sub- and supersaturated water vapor conditions.

    PubMed

    Herich, Hanna; Tritscher, Torsten; Wiacek, Aldona; Gysel, Martin; Weingartner, Ernest; Lohmann, Ulrike; Baltensperger, Urs; Cziczo, Daniel J

    2009-09-28

    Airborne mineral dust particles serve as cloud condensation nuclei (CCN), thereby influencing the formation and properties of warm clouds. It is therefore of atmospheric interest how dust aerosols with different mineralogy behave when exposed to high relative humidity (RH) or supersaturation (SS) with respect to liquid water. In this study the subsaturated hygroscopic growth and the supersaturated cloud condensation nucleus activity of pure clays and real desert dust aerosols were determined using a hygroscopicity tandem differential mobility analyzer (HTDMA) and a cloud condensation nuclei counter (CCNC), respectively. Five different illite, montmorillonite and kaolinite clay samples as well as three desert dust samples (Saharan dust (SD), Chinese dust (CD) and Arizona test dust (ATD)) were investigated. Aerosols were generated both with a wet and a dry disperser. The water uptake was parameterized via the hygroscopicity parameter kappa. The hygroscopicity of dry generated dust aerosols was found to be negligible when compared to processed atmospheric aerosols, with CCNC derived kappa values between 0.00 and 0.02 (the latter corresponds to a particle consisting of 96.7% by volume insoluble material and approximately 3.3% ammonium sulfate). Pure clay aerosols were generally found to be less hygroscopic than natural desert dust particles. The illite and montmorillonite samples had kappa approximately 0.003. The kaolinite samples were less hygroscopic and had kappa=0.001. SD (kappa=0.023) was found to be the most hygroscopic dry-generated desert dust followed by CD (kappa=0.007) and ATD (kappa=0.003). Wet-generated dust showed an increased water uptake when compared to dry-generated samples. This is considered to be an artifact introduced by redistribution of soluble material between the particles. Thus, the generation method is critically important when presenting such data. These results indicate any atmospheric processing of a fresh mineral dust particle which

  7. Water uptake of clay and desert dust aerosol particles at sub- and supersaturated water vapor conditions.

    PubMed

    Herich, Hanna; Tritscher, Torsten; Wiacek, Aldona; Gysel, Martin; Weingartner, Ernest; Lohmann, Ulrike; Baltensperger, Urs; Cziczo, Daniel J

    2009-09-28

    Airborne mineral dust particles serve as cloud condensation nuclei (CCN), thereby influencing the formation and properties of warm clouds. It is therefore of atmospheric interest how dust aerosols with different mineralogy behave when exposed to high relative humidity (RH) or supersaturation (SS) with respect to liquid water. In this study the subsaturated hygroscopic growth and the supersaturated cloud condensation nucleus activity of pure clays and real desert dust aerosols were determined using a hygroscopicity tandem differential mobility analyzer (HTDMA) and a cloud condensation nuclei counter (CCNC), respectively. Five different illite, montmorillonite and kaolinite clay samples as well as three desert dust samples (Saharan dust (SD), Chinese dust (CD) and Arizona test dust (ATD)) were investigated. Aerosols were generated both with a wet and a dry disperser. The water uptake was parameterized via the hygroscopicity parameter kappa. The hygroscopicity of dry generated dust aerosols was found to be negligible when compared to processed atmospheric aerosols, with CCNC derived kappa values between 0.00 and 0.02 (the latter corresponds to a particle consisting of 96.7% by volume insoluble material and approximately 3.3% ammonium sulfate). Pure clay aerosols were generally found to be less hygroscopic than natural desert dust particles. The illite and montmorillonite samples had kappa approximately 0.003. The kaolinite samples were less hygroscopic and had kappa=0.001. SD (kappa=0.023) was found to be the most hygroscopic dry-generated desert dust followed by CD (kappa=0.007) and ATD (kappa=0.003). Wet-generated dust showed an increased water uptake when compared to dry-generated samples. This is considered to be an artifact introduced by redistribution of soluble material between the particles. Thus, the generation method is critically important when presenting such data. These results indicate any atmospheric processing of a fresh mineral dust particle which

  8. Quantification of aerosol chemical composition using continuous single particle measurements

    NASA Astrophysics Data System (ADS)

    Jeong, C.-H.; McGuire, M. L.; Godri, K. J.; Slowik, J. G.; Rehbein, P. J. G.; Evans, G. J.

    2011-01-01

    Mass concentrations of particulate matter (PM) chemical components were determined from data for 0.3 to 3.0 μm particles measured by an Aerosol Time-of-Flight Mass Spectrometer (ATOFMS) data at an urban and rural site. Hourly-averaged concentrations of nitrate, sulphate, ammonium, organic carbon, and elemental carbon, estimated based on scaled ATOFMS peak intensities of corresponding ion marker species, were compared with collocated chemical composition measurements by an Aerosol Mass Spectrometer (AMS), a Gas-Particle Ion Chromatograph (GPIC), and a Sunset Lab field OCEC analyzer. The highest correlation was found for nitrate, with correlation coefficients (Pearson r) of 0.89 and 0.85 at the urban and rural sites, respectively. ATOFMS mass calibration factors, determined for the urban site, were used to calculate mass concentrations of the major PM chemical components at the rural site. Mass reconstruction using this ATOFMS based composition data agreed very well with the total PM mass measured at the rural site. Size distributions of the ten main types of particles were resolved for the rural site and the mass composition of each particle type was determined in terms of sulphate, nitrate, ammonium, organic carbon and elemental carbon. This is the first study to estimate hourly mass concentrations of individual aerosol components and the mass composition of individual particle-types based on ATOFMS single particle measurements.

  9. Single particle multichannel bio-aerosol fluorescence sensor

    NASA Astrophysics Data System (ADS)

    Kaye, P. H.; Stanley, W. R.; Hirst, E.; Foot, E. V.; Baxter, K. L.; Barrington, S. J.

    2005-05-01

    We describe a prototype low-cost multi-channel aerosol fluorescence sensor designed for unattended deployment in medium to large area bio-aerosol detection networks. Individual airborne particles down to ~1μm in size are detected and sized by measurement of light scattered from a continuous-wave diode laser (660nm). This scatter signal is then used to trigger the sequential firing of two xenon sources which irradiate the particle with UV pulses at ~280 nm and ~370 nm, optimal for excitation of bio-fluorophores tryptophan and NADH (nicotinamide adenine dinucleotide) respectively. For each excitation wavelength, fluorescence is detected across two bands embracing the peak emissions of the same bio-fluorophores. Current measurement rates are up to ~125 particles/s, corresponding to all particles for concentrations up to 1.3 x 104 particles/l. Developments to increase this to ~500 particles/s are in hand. Device sensitivity is illustrated in preliminary data recorded from aerosols of E.coli, BG spores, and a variety of non-biological materials.

  10. Glass formation processes in mixed inorganic/organic aerosol particles.

    PubMed

    Dette, Hans P; Koop, Thomas

    2015-05-14

    Recent experiments suggest that organic aerosol particles may transform into a glassy state at room temperature under dry conditions. Information on glass forming processes in mixed inorganic/organic aerosol particles is sparse, however, because inorganic crystal nucleation is usually very likely in such mixtures. Here we investigate the glass transition temperatures Tg of various organics (trehalose, sucrose, citric acid, sorbitol, and glycerol as well as 3-MBTCA) in binary mixtures with either NaNO3 or NH4HSO4 at different mass fractions. The glassy samples were prepared with the MARBLES technique by atomizing dilute aqueous solutions into aerosol particles and subsequent diffusion drying. The resulting aerosol particles were collected and their phase behavior was investigated using differential scanning calorimetry. At small and intermediate inorganic mass fractions salt crystallization did not occur. Instead, the single-phase mixtures remained in an amorphous state upon drying such that determination of their Tg was possible. From these measurements the Tg value of pure NaNO3 and pure NH4HSO4 could be inferred through extrapolation, resulting in values of Tg(NaNO3) ≈ 290 K and Tg(NH4HSO4) ≈ 220 K. Upon drying of NH4HSO4/3-MBTCA mixtures, phase-separated samples formed in which the inorganic-rich and organic-rich phases each show an independent glass transition. Our measurements provide a route toward establishing Tg values of inorganic salts that usually crystallize readily, and they may explain the reported contradicting observations of NaNO3 aerosol particles to either crystallize or remain amorphous upon drying at room temperature. PMID:25490407

  11. Dispersion of aerosol particles in the atmosphere: Fukushima

    NASA Astrophysics Data System (ADS)

    Haszpra, Tímea; Lagzi, István; Tél, Tamás

    2013-04-01

    Investigation of dispersion and deposition of aerosol particles in the atmosphere is an essential issue, because they have an effect on the biosphere and atmosphere. Moreover, aerosol particles have different transport properties and chemical and physical transformations in the atmosphere compared to gas phase air pollutants. The motion of a particle is described by a set of ordinary differential equations. The large-scale dynamics in the horizontal direction can be described by the equations of passive scalar advection, but in the vertical direction a well-defined terminal velocity should be taken into account as a term added to the vertical wind component. In the planetary boundary layer turbulent diffusion has an important role in the particle dispersion, which is taken into account by adding stochastic terms to the deterministic equations above. Wet deposition is also an essential process in the lower levels of the atmosphere, however, its precise parameterization is a challenge. For the simulations the wind field and other necessary data were taken from the ECMWF ERA-Interim database. In the case of the Fukushima Daiichi nuclear disaster (March-April 2011) radioactive aerosol particles were also released in the planetary boundary layer. Simulations (included the continuous and varying emission from the nuclear power plant) will be presented for the period of 14-23 March. Results show that wet deposition also has to be taken into consideration in the lower levels of the atmosphere. Furthermore, dynamical system characteristics are evaluated for the aerosol particle dynamics. The escape rate of particles was estimated both with and without turbulent diffusion, and in both cases when there was no wet deposition and also when wet deposition was taken into consideration.

  12. Design of Aerosol Particle Coating: Thickness, Texture and Efficiency

    PubMed Central

    Buesser, B.; Pratsinis, S.E.

    2013-01-01

    Core-shell particles preserve the performance (e.g. magnetic, plasmonic or opacifying) of a core material while modifying its surface with a shell that facilitates (e.g. by blocking its reactivity) their incorporation into a host liquid or polymer matrix. Here coating of titania (core) aerosol particles with thin silica shells (films or layers) is investigated at non-isothermal conditions by a trimodal aerosol dynamics model, accounting for SiO2 generation by gas phase and surface oxidation of hexamethyldisiloxane (HMDSO) vapor, coagulation and sintering. After TiO2 particles have reached their final primary particle size (e.g. upon completion of sintering during their flame synthesis), coating starts by uniformly mixing them with HMDSO vapor that is oxidized either in the gas phase or on the particles’ surface resulting in SiO2 aerosols or deposits, respectively. Sintering of SiO2 deposited onto the core TiO2 particles takes place transforming rough into smooth coating shells depending on process conditions. The core-shell characteristics (thickness, texture and efficiency) are calculated for two limiting cases of coating shells: perfectly smooth (e.g. hermetic) and fractal-like. At constant TiO2 core particle production rate, the influence of coating weight fraction, surface oxidation and core particle size on coating shell characteristics is investigated and compared to pertinent experimental data through coating diagrams. With an optimal temperature profile for complete precursor conversion, the TiO2 aerosol and SiO2-precursor (HMDSO) vapor concentrations have the strongest influence on product coating shell characteristics. PMID:23729833

  13. Spatial and Temporal Variability of Aerosol Particles in Arctic Spring

    SciTech Connect

    Shantz, Nicole C.; Gultepe, Ismail; Liu, Peter; Earle, Michael; Zelenyuk, Alla

    2012-10-01

    The objective of this work is to investigate the variability in the particle number concentration that may affect climate change assessment for Arctic regions. The Indirect and Semi-Direct Aerosol Campaign (ISDAC) was conducted in April 2008, in the vicinities of Fairbanks and Barrow, Alaska. Measurements of particle number concentrations and size distributions were conducted using a Passive Cavity Aerosol Spectrometer Probe (PCASP-100X) mounted under the Convair-580 aircraft wing. Total number concentration of particles (Na) with diameters in the range 0.12-3 μm was determined for polluted and clean air masses during times when the air was free of clouds and/or precipitation. Variability in Na was considered for both vertical profiles and constant altitude (horizontal) flight legs. This variability can have important implications for estimates of particle properties used in global climate model (GCM) simulations. When aerosol particle layers were encountered, Na rapidly increased from 25 cm-3 up to 550 cm-3 within relatively clean air masses, and reached up to 2200 cm-3 within polluted air masses, dominated by biomass burning pollution. When averaging Na over different distance scales, it was found that Na=140 cm-3 represent an average value for the majority of the encountered clean cases; while Na=720 cm-3 is a mean for polluted cases dominated by biomass burning plumes. These estimates, however, would not capture the details of particle layers encountered during most of the flights. Average aerosol particle characteristics can be difficult to interpret, especially during polluted cases, due to small-scale spatial and temporal variability.

  14. Characterization of aerosol particles at the forested site in Lithuania

    NASA Astrophysics Data System (ADS)

    Rimselyte, I.; Garbaras, A.; Kvietkus, K.; Remeikis, V.

    2009-04-01

    Atmospheric particulate matter (PM), especially fine particles (particles with aerodynamic diameter less than 1 m, PM1), has been found to play an important role in global climate change, air quality, and human health. The continuous study of aerosol parameters is therefore imperative for better understanding the environmental effects of the atmospheric particles, as well as their sources, formation and transformation processes. The particle size distribution is particularly important, since this physical parameter determines the mass and number density, lifetime and atmospheric transport, or optical scattering behavior of the particles in the atmosphere (Jaenicke, 1998). Over the years several efforts have been made to improve the knowledge about the chemical composition of atmospheric particles as a function of size (Samara and Voutsa, 2005) and to characterize the relative contribution of different components to the fine particulate matter. It is well established that organic materials constitute a highly variable fraction of the atmospheric aerosol. This fraction is predominantly found in the fine size mode in concentrations ranging from 10 to 70% of the total dry fine particle mass (Middlebrook et al., 1998). Although organic compounds are major components of the fine particles, the composition, formation mechanism of organic aerosols are not well understood. This is because particulate organic matter is part of a complex atmospheric system with hundreds of different compounds, both natural and anthropogenic, covering a wide range of chemical properties. The aim of this study was to characterize the forest PM1, and investigate effects of air mass transport on the aerosol size distribution and chemical composition, estimate and provide insights into the sources and characteristics of carbonaceous aerosols through analysis ^13C/12C isotopic ratio as a function of the aerosol particles size. The measurements were performed at the Rugšteliškis integrated

  15. Aerosol mixing state, hygroscopic growth and cloud activation efficiency during MIRAGE 2006

    NASA Astrophysics Data System (ADS)

    Lance, S.; Raatikainen, T.; Onasch, T. B.; Worsnop, D. R.; Yu, X.-Y.; Alexander, M. L.; Stolzenburg, M. R.; McMurry, P. H.; Smith, J. N.; Nenes, A.

    2013-05-01

    Observations of aerosol hygroscopic growth and CCN activation spectra for submicron particles are reported for the T1 ground site outside of Mexico City during the MIRAGE 2006 campaign. κ-Köhler theory is used to evaluate the characteristic hygroscopicity parameter, κ*, for the CCN active aerosol population using both size-resolved HTMDA and size-resolved CCNc measurements. Organic mass fractions (forg) are evaluated from size-resolved aerosol mass spectrometer (AMS) measurements, from which predictions of the hygroscopicity parameter are compared against κ*. Strong diurnal changes in aerosol water uptake parameters and aerosol composition are observed. We find that new particle formation (NPF) events are correlated with an increased κ* and CCN-active fraction during the daytime, with greater impact on smaller particles. During NPF events, the number concentration of 40 nm particles acting as CCN at 0.51% ± 0.06% supersaturation can surpass by more than a factor of two the corresponding concentrations of 100 nm particles. We also find that at 06:00-08:00 LT throughout the campaign, fresh traffic emissions result in substantial changes to the chemical distribution of the aerosol, with on average 65% externally mixed fraction for 40 nm particles and 30% externally mixed fraction for 100 nm particles, whereas at midday nearly all particles of both sizes can be described as "internally mixed". Average activation spectra and growth factor distributions are analyzed for different time periods characterizing the daytime (with and without NPF events), the early morning "rush hour" and the entire campaign. We show that κ* derived from CCNc measurements decreases as a function of size during all time periods, while the CCN-active fraction increases as a function of size. Size-resolved AMS measurements do not predict the observed trend for κ* versus particle size, which can be attributed to unresolved mixing state and the presence of refractory material not measured

  16. Production, Organic Characterization, and Phase Transformations of Marine Particles Aerosolized from a Laboratory Mesocosm Phytoplankton Bioreactor

    NASA Astrophysics Data System (ADS)

    Alpert, P. A.; Knopf, D. A.; Aller, J. Y.; Radway, J.; Kilthau, W.

    2012-12-01

    Previous studies have shown that particles emitted from bubble bursting and wave breaking of ocean waters with high biological activity can contain sea salts associated with organic material, with smaller particles containing a larger mass fraction of organics than larger particles. This likely indicates a link between phytoplankton productivity in oceans and particulate organic material in marine air. Once aerosolized, particles with significant amount of organic material can affect cloud activation and formation of ice crystals, among other atmospheric processes, thus influencing climate. This is significant for clouds and climate particularly over nutrient rich polar seas, in which concentrations of biological organisms can reach up to 109 cells per ml during spring phytoplankton blooms. Here we present results of bubble bursting aerosol production from a seawater mesocosm containing artificial seawater, natural seawater and unialgal cultures of three representative phytoplankton species. These phytoplankton (Thalassiosira pseudonana, Emilianaia huxleyi, and Nannochloris atomus), possessed siliceous frustules, calcareous frustules and no frustules, respectively. Bubbles were generated employing recirculating impinging water jets or glass frits. Dry and humidified aerosol size distributions and bulk aerosol organic composition were measured as a function of phytoplankton growth, and chlorophyll composition and particulate and dissolved organic carbon in the water were determined. Finally, particles were collected on substrates for ice nucleation and water uptake experiments, their elemental compositions were determined using computer controlled scanning electron microscopy and energy dispersive analysis of X-rays (CCSEMEDAX), and their carbon speciation was determined using scanning transmission X-ray microscopy and near-edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS). Particle size distributions exposed to dry and humidified air employing

  17. Coagulation of monodisperse aerosol particles by isotropic turbulence

    NASA Astrophysics Data System (ADS)

    Chun, J.; Koch, D. L.

    2005-02-01

    The rate of coagulation of initially monodisperse aerosols due to isotropic turbulence is studied with particular emphasis on the effects of noncontinuum hydrodynamics and particle inertia. The prevalence of these two factors distinguishes aerosol coagulation from the coagulation of colloidal particles. The turbulent flow seen by an interacting pair of particles is modelled as a stochastically varying flow field that is a linear function of position. This approximation is valid because the 1-10 micron diameter particles for which turbulence dominates coagulation are much smaller than the smallest eddies of a typical turbulent flow field. It is shown that the finite mean-free path of the gas enhances the rate of coagulation and leads to a finite coagulation rate even in the absence of van der Waals attractions. The coupled effects of turbulent shear and Brownian motion are treated. As in the case of laminar shear flows, it is found that Brownian motion plays an important role in the coagulation process even when the Peclet number is moderately large. It is shown that particle inertia increases the coagulation rate in two ways. First, preferential concentration increases the radial distribution function on length scales intermediate between the Kolmogorov length scale and the particle diameter. Second, the greater persistence of particles' relative motion during their local interaction leads to an increase in coagulation rate with increasing particle Stokes number.

  18. Endotoxin in Size-Separated Metal Working Fluid Aerosol Particles.

    PubMed

    Dahlman-Höglund, Anna; Lindgren, Åsa; Mattsby-Baltzer, Inger

    2016-08-01

    Patients with airway symptoms working in metal working industries are increasing, despite efforts to improve the environmental air surrounding the machines. Our aim was to analyse the amount of endotoxin in size-separated airborne particles of metal working fluid (MWF) aerosol, by using the personal sampler Sioutas cascade impactor, to compare filter types, and to compare the concentration of airborne endotoxin to that of the corresponding MWFs. In a pilot field study, aerosols were collected in two separate machine halls on totally 10 occasions, using glass fibre and polytetrafluoroethylene (PTFE) filters in parallel at each station. Airborne endotoxin was distributed over all size fractions. While a major part was found in the largest size fraction (72%, 2.5-10 µm), up to 8% of the airborne endotoxin was detected in the smallest size fraction (<0.25 µm). Comparing the efficiency of the filter types, a significantly higher median endotoxin level was found with glass fibres filters collecting the largest particle-size fraction (1.2-fold) and with PTFE filters collecting the smallest ones (5-fold). The levels of endotoxin in the size-separated airborne particle fractions correlated to those of the MWFs supporting the aerosol-generating machines. Our study indicates that a significant part of inhalable aerosols of MWFs consists of endotoxin-containing particles below the size of intact bacteria, and thus small enough to readily reach the deepest part of the lung. Combined with other chemical irritants of the MWF, exposure to MWF aerosols containing endotoxin pose a risk to respiratory health problems. PMID:27268595

  19. Hygroscopic properties of levoglucosan and related organic compounds characteristic to biomass burning aerosol particles

    NASA Astrophysics Data System (ADS)

    Mochida, Michihiro; Kawamura, Kimitaka

    2004-11-01

    Biomass burning, which is characterized by pyrolysis as well as vaporization and condensation of biomass constituents, is a significant source of atmospheric organic aerosols. In this study, hygroscopic properties of five organic compounds (levoglucosan, D-glucose, and vanillic, syringic, and 4-hydroxybenozoic acids), which are major pyrolysis products of wood, were measured using a tandem differential mobility analyzer. Levoglucosan, which is typically the most abundant species in wood burning aerosols, showed a significant hygroscopic growth for particles with a diameter of 100 nm. No efflorescence was observed under the measured relative humidity, and a supersaturated condition of levoglucosan-water particles was observed. The growth factors of levoglucosan are 1.08, 1.18, 1.23, and 1.38 at relative humidity (RH) of 60, 80, 85, and 90%, respectively. The measured hygroscopic curves are in general consistent with those estimated from ideal solution theory and Uniquac Functional-Group Activity Coefficient (UNIFAC) and Conductor-Like Screening Model for Real Solvent (COSMO-RS) methods. Significant hygroscopic growth was also observed for D-glucose, whose growth factor is quite similar to that of levoglucosan. However, three model pyrolysis products of lignin (i.e., vanillic-, syringic-, and 4-hydroxybenzoic acids) did not show any hygroscopic growth under the RH conditions up to 95%. On the basis of the organic composition of wood burning aerosols, the water absorption attributed to levoglucosan in wood burning aerosols is calculated to be up to 30% of the organic mass at 90% RH. This study demonstrates that oxygenated organics emitted from biomass burning could significantly enhance the hygroscopic properties of atmospheric aerosols.

  20. Chemical evolution of multicomponent aerosol particles during evaporation

    NASA Astrophysics Data System (ADS)

    Zardini, Alessandro; Riipinen, Ilona; Pagels, Joakim; Eriksson, Axel; Worsnop, Douglas; Switieckli, Erik; Kulmala, Markku; Bilde, Merete

    2010-05-01

    Atmospheric aerosol particles have an important but not well quantified effect on climate and human health. Despite the efforts made in the last decades, the formation and evolution of aerosol particles in the atmosphere is still not fully understood. The uncertainty is partly due to the complex chemical composition of the particles which comprise inorganic and organic compounds. Many organics (like dicarboxylic acids) can be present both in the gas and in the condensed phase due to their low vapor pressure. Clearly, an understanding of this partition is crucial to address any other issue in atmospheric physics and chemistry. Moreover, many organics are water soluble, and their influence on the properties of aqueous solution droplets is still poorly characterized. The solid and sub-cooled liquid state vapor pressures of some organic compounds have been previously determined by measuring the evaporation rate of single-compound crystals [1-3] or binary aqueous droplets [4-6]. In this work, we deploy the HTDMA technique (Hygroscopicity Tandem Differential Mobility Analyzer) coupled with a 3.5m laminar flow-tube and an Aerosol Mass Spectrometer (AMS) for determining the chemical evolution during evaporation of ternary droplets made of one dicarboxylic acid (succinic acid, commonly found in atmospheric samples) and one inorganic compound (sodium chloride or ammonium sulfate) in different mixing ratios, in equilibrium with water vapor at a fixed relative humidity. In addition, we investigate the evaporation of multicomponent droplets and crystals made of three organic species (dicarboxylic acids and sugars), of which one or two are semi-volatile. 1. Bilde M. and Pandis, S.N.: Evaporation Rates and Vapor Pressures of Individual Aerosol Species Formed in the Atmospheric Oxidation of alpha- and beta-Pinene. Environmental Science and Technology, 35, 2001. 2. Bilde M., et al.: Even-Odd Alternation of Evaporation Rates and Vapor Pressures of C3-C9 Dicarboxylic Acid Aerosols

  1. Quantification of aerosol chemical composition using continuous single particle measurements

    NASA Astrophysics Data System (ADS)

    Jeong, C.-H.; McGuire, M. L.; Godri, K. J.; Slowik, J. G.; Rehbein, P. J. G.; Evans, G. J.

    2011-07-01

    Mass concentrations of sulphate, nitrate, ammonium, organic carbon (OC), elemental carbon (EC) were determined from real time single particle data in the size range 0.1-3.0 μm measured by an Aerosol Time-of-Flight Mass Spectrometer (ATOFMS) at urban and rural sites in Canada. To quantify chemical species within individual particles measured by an ATOFMS, ion peak intensity of m/z -97 for sulphate, -62 for nitrate, +18 for ammonium, +43 for OC, and +36 for EC were scaled using the number and size distribution data by an Aerodynamic Particle Sizer (APS) and a Fast Mobility Particle Sizer (FMPS). Hourly quantified chemical species from ATOFMS single-particle analysis were compared with collocated fine particulate matter (aerodynamic diameter < 2.5 μm, PM2.5) chemical composition measurements by an Aerosol Mass Spectrometer (AMS) at a rural site, a Gas-Particle Ion Chromatograph (GPIC) at an urban site, and a Sunset Lab field OCEC analyzer at both sites. The highest correlation was found for nitrate, with correlation coefficients (Pearson r) of 0.89 (ATOFMS vs. GPIC) and 0.85 (ATOFMS vs. AMS). ATOFMS mass calibration factors, determined for the urban site, were used to calculate mass concentrations of the major PM2.5 chemical components at the rural site near the US border in southern Ontario. Mass reconstruction using the ATOFMS mass calibration factors agreed very well with the PM2.5 mass concentrations measured by a Tapered Element Oscillating Microbalance (TEOM, r = 0.86) at the urban site and a light scattering monitor (DustTrak, r = 0.87) at the rural site. In the urban area nitrate was the largest contributor to PM2.5 mass in the winter, while organics and sulphate contributed ~64 % of the summer PM2.5 in the rural area, suggesting a strong influence of regional/trans-boundary pollution. The mass concentrations of five major species in ten size-resolved particle-types and aerosol acidity of each particle-type were determined for the rural site. On a mass basis

  2. Atmospheric Chemistry: Nature's plasticized aerosols

    NASA Astrophysics Data System (ADS)

    Ziemann, Paul J.

    2016-01-01

    The structure of atmospheric aerosol particles affects their reactivity and growth rates. Measurements of aerosol properties over the Amazon rainforest indicate that organic particles above tropical rainforests are simple liquid drops.

  3. PARTICLE SIZE DISTRIBUTIONS FOR AN OFFICE AEROSOL

    EPA Science Inventory

    The article discusses an evaluation of the effect of percent outdoor air supplied and occupation level on the particle size distributions and mass concentrations for a typical office building. (NOTE: As attention has become focused on indoor air pollution control, it has become i...

  4. Morphologies of aerosol particles consisting of two liquid phases

    NASA Astrophysics Data System (ADS)

    Song, Mijung; Marcolli, Claudia; Krieger, Ulrich; Peter, Thomas

    2013-04-01

    Recent studies have shown that liquid-liquid phase separation (LLPS) might be a common feature in mixed organic/ammonium sulfate (AS)/H2O particles. Song et al. (2012) observed that in atmospheric relevant organic/AS/H2O mixtures LLPS always occurred for organic aerosol compositions with O:C < 0.56, depended on the specific functional groups of organics in the range of 0.56 < O:C < 0.80 and never appeared for O:C > 0.80. The composition of the organic fraction and the mixing state of aerosol particles may influence deliquescence relative humidity (DRH) and efflorescence relative humidity (ERH) of inorganic salts during RH cycles and also aerosol morphology. In order to determine how the deliquescence and efflorescence of AS in mixed organic/AS/H2O particles is influenced by LLPS and to identify the corresponding morphologies of the particles, we subjected organic/AS/H2O particles deposited on a hydrophobically coated substrate to RH cycles and observed the phase transitions using optical microscopy and Raman spectroscopy. In this study, we report results from 21 organic/AS/H2O systems with O:C ranging from 0.55 - 0.85 covering aliphatic and aromatic oxidized compounds. Eight systems did not show LLPS for all investigated organic-to-inorganic ratios, nine showed core-shell morphology when present in a two-liquid-phases state and four showed both, core-shell or partially engulfed configurations depending on the organic-to-inorganic ratio. While AS in aerosol particles with complete LLPS showed almost constant values of ERH = 44 ± 4 % and DRH = 77 ± 2 %, a strong reduction or complete inhibition of efflorescence occurred for mixtures that did not exhibit LLPS. To confirm these findings, we performed supplementary experiments on levitated particles in an electrodynamic balance and compared surface and interfacial tensions of the investigated mixtures. Reference Song, M., C. Marcolli, U. K. Krieger, A. Zuend, and T. Peter (2012), Liquid-liquid phase separation in

  5. Neural networks for aerosol particles characterization

    NASA Astrophysics Data System (ADS)

    Berdnik, V. V.; Loiko, V. A.

    2016-11-01

    Multilayer perceptron neural networks with one, two and three inputs are built to retrieve parameters of spherical homogeneous nonabsorbing particle. The refractive index ranges from 1.3 to 1.7; particle radius ranges from 0.251 μm to 56.234 μm. The logarithms of the scattered radiation intensity are used as input signals. The problem of the most informative scattering angles selection is elucidated. It is shown that polychromatic illumination helps one to increase significantly the retrieval accuracy. In the absence of measurement errors relative error of radius retrieval by the neural network with three inputs is 0.54%, relative error of the refractive index retrieval is 0.84%. The effect of measurement errors on the result of retrieval is simulated.

  6. Glyoxal and Methylglyoxal in Atlantic Seawater and marine Aerosol Particles

    NASA Astrophysics Data System (ADS)

    van Pinxteren, Manuela; Herrmann, Hartmut

    2014-05-01

    The two α-dicarbonyls glyoxal (CHOCHO; GLY) and methylglyoxal (CH3COCHO; MGLY) have attracted increasing attention over the past years because of their potential role in secondary organic aerosol formation. Recently Sinreich et al. (2010) suggested the open ocean as an important (so far unknown) source for GLY in the atmosphere. To date, there are few available field data of these compounds in the marine area. In this study we present measurements of GLY and MGLY in seawater and marine aerosol particles sampled during a transatlantic Polarstern cruise in spring 2011. In seawater we especially investigated the sea surface microlayer (sampled with the glass plate technique) as it is the direct interface between ocean and atmosphere. Analytical measurements were based on derivatisation with o-(2,3,4,5,6-Pentafluorobenzyl)-hydroxylamine reagent, solvent extraction and GC-MS (SIM) analysis. The results show that GLY and MGLY are present in the sea surface microlayer of the ocean and corresponding bulkwater with average concentrations of 228 ng L-1 (GLY) and 196 ng L-1 (MGLY). Significant enrichment (factor of 4) of GLY and MGLY in the sea surface microlayer was found implying photochemical production of the two carbonyls though a clear connection to global radiation was not observed. On aerosol particles, both carbonyls were detected (average concentration 0.2 ng m-3) and are strongly connected to each other, suggesting similar formation mechanisms. Both carbonyls show a very good correlation with particulate oxalate, supporting the idea of a secondary formation of oxalic acid via GLY and MGLY. A slight correlation of the two carbonyls in the sea surface microlayer and in the aerosol particles was found at co-located sampling areas. In summary, the results of GLY and MGLY in marine aerosol particles and in the oceanic water give first insights towards interaction processes of these alpha dicarbonyls between ocean and atmosphere (van Pinxteren and Herrmann (2013

  7. Morphology and Optical Properties of Mixed Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Fard, Mehrnoush M.; Krieger, Ulrich; Rudich, Yinon; Marcolli, Claudia; Peter, Thomas

    2015-04-01

    Experiments and modeling studies have shown that deliquesced aerosols can be present not only as one-phase system containing organics, inorganic salts and water, but often as two-phase systems consisting of a predominantly organic and a predominantly inorganic aqueous phase 1,2. Recent laboratory studies conducted with model mixtures representing tropospheric aerosols1,2,3, secondary organic aerosol (SOA) from smog chamber experiments4, and field measurements5 suggest that liquid- liquid phase separations (LLPS) is indeed a common phenomenon in mixed organic/ ammonium sulfate (AS) particles. During LLPS, particles may adopt different morphologies mainly core- shell and partially engulfed. A core- shell configuration will have consequences for heterogeneous chemistry and hygroscopicity and as a result will alter the optical properties of the particles since the aqueous inorganic-rich phase will be totally enclosed by a probably highly viscous organic coating with low diffusivity for reactants and water. The primary objective of this project is to establish a method for investigating the morphology of mixed inorganic and absorbing organic compounds of atmospheric relevance and study their radiative properties before, during, and after phase transitions mainly during LLPS. This will be the first study looking into the radiative effect of LLPS in detail. In this first experiment, the behavior of single droplets of carminic acid (CA)/ AS/ H2O mixture was monitored during relative humidity (RH) cycles using optical microscopy. The same mixture particle was levitated in an electrodynamic balance (EDB) and the change in its absorption properties was measured at varying RH. We also intend to determine the occurrence of LLPS in accumulation- sized particles and the change in their absorption using a cavity ring down aerosol spectrometer. If LLPS alters the absorptive properties of the suggested model aerosols significantly, absorption measurements of accumulation mode

  8. Aerosol growth in Titan’s ionosphere

    PubMed Central

    Lavvas, Panayotis; Yelle, Roger V.; Koskinen, Tommi; Bazin, Axel; Vuitton, Véronique; Vigren, Erik; Galand, Marina; Wellbrock, Anne; Coates, Andrew J.; Wahlund, Jan-Erik; Crary, Frank J.; Snowden, Darci

    2013-01-01

    Photochemically produced aerosols are common among the atmospheres of our solar system and beyond. Observations and models have shown that photochemical aerosols have direct consequences on atmospheric properties as well as important astrobiological ramifications, but the mechanisms involved in their formation remain unclear. Here we show that the formation of aerosols in Titan’s upper atmosphere is directly related to ion processes, and we provide a complete interpretation of observed mass spectra by the Cassini instruments from small to large masses. Because all planetary atmospheres possess ionospheres, we anticipate that the mechanisms identified here will be efficient in other environments as well, modulated by the chemical complexity of each atmosphere. PMID:23382231

  9. Fluorescence lifetime imaging of optically levitated aerosol: a technique to quantitatively map the viscosity of suspended aerosol particles.

    PubMed

    Fitzgerald, C; Hosny, N A; Tong, H; Seville, P C; Gallimore, P J; Davidson, N M; Athanasiadis, A; Botchway, S W; Ward, A D; Kalberer, M; Kuimova, M K; Pope, F D

    2016-08-21

    We describe a technique to measure the viscosity of stably levitated single micron-sized aerosol particles. Particle levitation allows the aerosol phase to be probed in the absence of potentially artefact-causing surfaces. To achieve this feat, we combined two laser based techniques: optical trapping for aerosol particle levitation, using a counter-propagating laser beam configuration, and fluorescent lifetime imaging microscopy (FLIM) of molecular rotors for the measurement of viscosity within the particle. Unlike other techniques used to measure aerosol particle viscosity, this allows for the non-destructive probing of viscosity of aerosol particles without interference from surfaces. The well-described viscosity of sucrose aerosol, under a range of relative humidity conditions, is used to validate the technique. Furthermore we investigate a pharmaceutically-relevant mixture of sodium chloride and salbutamol sulphate under humidities representative of in vivo drug inhalation. Finally, we provide a methodology for incorporating molecular rotors into already levitated particles, thereby making the FLIM/optical trapping technique applicable to real world aerosol systems, such as atmospheric aerosols and those generated by pharmaceutical inhalers. PMID:27430158

  10. Code System to Calculate Particle Penetration Through Aerosol Transport Lines.

    1999-07-14

    Version 00 Distribution is restricted to US Government Agencies and Their Contractors Only. DEPOSITION1.03 is an interactive software program which was developed for the design and analysis of aerosol transport lines. Models are presented for calculating aerosol particle penetration through straight tubes of arbitrary orientation, inlets, and elbows. An expression to calculate effective depositional velocities of particles on tube walls is derived. The concept of maximum penetration is introduced, which is the maximum possible penetrationmore » through a sampling line connecting any two points in a three-dimensional space. A procedure to predict optimum tube diameter for an existing transport line is developed. Note that there is a discrepancy in this package which includes the DEPOSITION 1.03 executable and the DEPOSITION 2.0 report. RSICC was unable to obtain other executables or reports.« less

  11. Hygroscopic Growth and Activation of Particles containing Algea-Exudate

    NASA Astrophysics Data System (ADS)

    Wex, Heike; Fuentes, Elena; Tsagkogeorgas, Georgios; Voigtländer, Jens; Clauss, Tina; Kiselev, Alexei; Green, David; Coe, Hugh; McFiggans, Gordon; Stratmann, Frank

    2010-05-01

    A large amount of the Earth is covered by oceans, which provide a constant source of marine aerosol particles, produced due to bubble bursting processes that depend on wind speed (O'Dowd and de Leeuw, 2007). In general, marine particles can be assumed to play an important role for the Earth atmosphere on a global scale, due to their abundance and due to their effect on clouds. E.g. marine stratus and stratocumulus clouds contribute about 30% to 40% to the Earth's albedo (Randall et al., 1984). The activation of aerosol particles to cloud droplets depends on the hygroscopic properties of the particles, which, in turn, depend on their chemical composition. For marine particles, is has been and still is discussed what the effects of organic substances being present in the particles might be. These substances originate from marine biota where they enrich at the ocean surface. To mimic marine aerosol particles, algae-exudates of different algae species were mixed with artificial sea-water. These samples were used in the laboratory to produce particles via a bubble bursting process (Fuentes et al., 2009). The hygroscopic growth and activation of the (size selected) particles was measured, using LACIS (Leipzig Aerosol Cloud Interaction Simulator, Stratmann et al., 2004) and the DMT-CCNc (Cloud Condensation Nucleus counter from Droplet Measurement Technologies, Roberts and Nenes, 2005). The hygroscopic growth was measured twice, 3 and 10 seconds after humidification, and no difference in the grown size was detected, i.e. no kinetic effect was observed for the examined time range. From LACIS and CCNc measurements, the hygroscopicity was deduced through determination of the amount of ions being effective in the particle / droplet solution (Rho(ion), Wex et al., 2007). A concentration dependent non-ideal behaviour was found for particles produced from an artificial sea-water sample that contained only inorganic salts, as can be expected (see e.g. Niedermeier et al., 2008

  12. Variations in hygroscopic growth of sub- and super-micron sea spray aerosols during a phytoplankton bloom

    NASA Astrophysics Data System (ADS)

    Forestieri, S.; Jayarathne, T. S.; Stone, E. A.; Laskina, O.; Grassian, V. H.; Lee, C.; Sultana, C. M.; Moore, K.; Cornwell, G.; Novak, G.; Bertram, T. H.; Prather, K. A.; Cappa, C. D.

    2014-12-01

    Marine sea spray aerosols (SSA) make up an important portion of natural aerosols (prior to anthropogenic influence) and are therefore important in establishing the baseline for anthropogenic aerosol climate impacts. One way aerosols impact climate is by scattering solar radiation, and how much light is scattered depends upon the size of aerosols. Aerosols grow larger via water uptake and thus scatter more light at elevated relative humidities. This growth depends on composition. SSA can become enriched in organics during phytoplankton blooms, becoming less salty and therefore less hygroscopic. Aerosol hygroscopicity of SSA sampled during an in-lab phytoplankton bloom were measured during the CAICE-IMPACTS 2014 study. SSA were generated via breaking waves in an enclosed 33 m wave channel filled with natural seawater. Aerosol hygroscopicity was characterized by measuring light extinction at 532 nm of dry aerosols and of aerosols humidified to 85% relative humidity using a Cavity Ringdown Spectrometer. These optical growth factors (humidified extinction/dry extinction) were converted to physical growth factors using Mie Theory calculations and aerosol size distributions measured with a scanning electrical mobility spectrometer (SEMS) and an aerodynamic particle sizer (APS). Growth factors for super- and sub-micron SSA were quantified separately through the use of a PM2.5 cyclone or PM1 impactor. The observed SSA growth factors will be linked to SSA and source water chemical composition determined by both offline and online analysis of samples. The SSA bulk growth factors will also be compared with concurrent measurements of the efficiency with which SSA act as cloud condensation nuclei. Observed SSA growth factors will also be compared to offline hygroscopic growth measurements.

  13. Characterization of aerosol particles at the forested site in Lithuania

    NASA Astrophysics Data System (ADS)

    Rimselyte, I.; Garbaras, A.; Kvietkus, K.; Remeikis, V.

    2009-04-01

    Atmospheric particulate matter (PM), especially fine particles (particles with aerodynamic diameter less than 1 m, PM1), has been found to play an important role in global climate change, air quality, and human health. The continuous study of aerosol parameters is therefore imperative for better understanding the environmental effects of the atmospheric particles, as well as their sources, formation and transformation processes. The particle size distribution is particularly important, since this physical parameter determines the mass and number density, lifetime and atmospheric transport, or optical scattering behavior of the particles in the atmosphere (Jaenicke, 1998). Over the years several efforts have been made to improve the knowledge about the chemical composition of atmospheric particles as a function of size (Samara and Voutsa, 2005) and to characterize the relative contribution of different components to the fine particulate matter. It is well established that organic materials constitute a highly variable fraction of the atmospheric aerosol. This fraction is predominantly found in the fine size mode in concentrations ranging from 10 to 70% of the total dry fine particle mass (Middlebrook et al., 1998). Although organic compounds are major components of the fine particles, the composition, formation mechanism of organic aerosols are not well understood. This is because particulate organic matter is part of a complex atmospheric system with hundreds of different compounds, both natural and anthropogenic, covering a wide range of chemical properties. The aim of this study was to characterize the forest PM1, and investigate effects of air mass transport on the aerosol size distribution and chemical composition, estimate and provide insights into the sources and characteristics of carbonaceous aerosols through analysis ^13C/12C isotopic ratio as a function of the aerosol particles size. The measurements were performed at the Rugšteliškis integrated

  14. Formation of Secondary Particulate Matter by Reactions of Gas Phase Hexanal with Sulfate Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Zhang, J.

    2003-12-01

    The formation of secondary particulate matter from the atmospheric oxidation of organic compounds can significantly contribute to the particulate burden, but the formation of organic secondary particulate matter is poorly understood. One way of producing organic secondary particulate matter is the oxidation of hydrocarbons with seven or more carbon atoms to get products with low vapor pressure. However, several recent reports suggest that relatively low molecular weight carbonyls can enter the particle phase by undergoing heterogeneous reactions. This may be a very important mechanism for the formation of organic secondary particulate matter. Atmospheric aldehydes are important carbonyls in the gas phase, which form via the oxidation of hydrocarbons emitted from anthropogenic and biogenic sources. In this poster, we report the results on particle growth by the heterogeneous reactions of hexanal. A 5 L Continuous Stirred Tank Reactor (CSTR) is set up to conduct the reactions in the presence of seed aerosol particles of deliquesced ammonia bisulfate. Hexanal is added into CSTR by syringe pump, meanwhile the concentrations of hexanal are monitored with High Pressure Liquid Chromatograph (HPLC 1050). A differential Mobility Analyzer (TSI 3071) set to an appropriate voltage is employed to obtain monodisperse aerosols, and another DMA associated with a Condensation Nuclear Counter (TSI 7610) is used to measure the secondary particle size distribution by the reaction in CSTR. This permits the sensitive determination of particle growth due to the heterogeneous reaction, very little growth occurs when hexanal added alone. Results for the simultaneous addition of hexanal and alcohols will also be presented.

  15. An amorphous solid state of biogenic secondary organic aerosol particles.

    PubMed

    Virtanen, Annele; Joutsensaari, Jorma; Koop, Thomas; Kannosto, Jonna; Yli-Pirilä, Pasi; Leskinen, Jani; Mäkelä, Jyrki M; Holopainen, Jarmo K; Pöschl, Ulrich; Kulmala, Markku; Worsnop, Douglas R; Laaksonen, Ari

    2010-10-14

    Secondary organic aerosol (SOA) particles are formed in the atmosphere from condensable oxidation products of anthropogenic and biogenic volatile organic compounds (VOCs). On a global scale, biogenic VOCs account for about 90% of VOC emissions and of SOA formation (90 billion kilograms of carbon per year). SOA particles can scatter radiation and act as cloud condensation or ice nuclei, and thereby influence the Earth's radiation balance and climate. They consist of a myriad of different compounds with varying physicochemical properties, and little information is available on the phase state of SOA particles. Gas-particle partitioning models usually assume that SOA particles are liquid, but here we present experimental evidence that they can be solid under ambient conditions. We investigated biogenic SOA particles formed from oxidation products of VOCs in plant chamber experiments and in boreal forests within a few hours after atmospheric nucleation events. On the basis of observed particle bouncing in an aerosol impactor and of electron microscopy we conclude that biogenic SOA particles can adopt an amorphous solid-most probably glassy-state. This amorphous solid state should provoke a rethinking of SOA processes because it may influence the partitioning of semi-volatile compounds, reduce the rate of heterogeneous chemical reactions, affect the particles' ability to accommodate water and act as cloud condensation or ice nuclei, and change the atmospheric lifetime of the particles. Thus, the results of this study challenge traditional views of the kinetics and thermodynamics of SOA formation and transformation in the atmosphere and their implications for air quality and climate.

  16. An amorphous solid state of biogenic secondary organic aerosol particles.

    PubMed

    Virtanen, Annele; Joutsensaari, Jorma; Koop, Thomas; Kannosto, Jonna; Yli-Pirilä, Pasi; Leskinen, Jani; Mäkelä, Jyrki M; Holopainen, Jarmo K; Pöschl, Ulrich; Kulmala, Markku; Worsnop, Douglas R; Laaksonen, Ari

    2010-10-14

    Secondary organic aerosol (SOA) particles are formed in the atmosphere from condensable oxidation products of anthropogenic and biogenic volatile organic compounds (VOCs). On a global scale, biogenic VOCs account for about 90% of VOC emissions and of SOA formation (90 billion kilograms of carbon per year). SOA particles can scatter radiation and act as cloud condensation or ice nuclei, and thereby influence the Earth's radiation balance and climate. They consist of a myriad of different compounds with varying physicochemical properties, and little information is available on the phase state of SOA particles. Gas-particle partitioning models usually assume that SOA particles are liquid, but here we present experimental evidence that they can be solid under ambient conditions. We investigated biogenic SOA particles formed from oxidation products of VOCs in plant chamber experiments and in boreal forests within a few hours after atmospheric nucleation events. On the basis of observed particle bouncing in an aerosol impactor and of electron microscopy we conclude that biogenic SOA particles can adopt an amorphous solid-most probably glassy-state. This amorphous solid state should provoke a rethinking of SOA processes because it may influence the partitioning of semi-volatile compounds, reduce the rate of heterogeneous chemical reactions, affect the particles' ability to accommodate water and act as cloud condensation or ice nuclei, and change the atmospheric lifetime of the particles. Thus, the results of this study challenge traditional views of the kinetics and thermodynamics of SOA formation and transformation in the atmosphere and their implications for air quality and climate. PMID:20944744

  17. Virtual Impactor for Sub-micron Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Bolshakov, A. A.; Strawa, A. W.; Hallar, A. G.

    2005-12-01

    The objective of a virtual impactor is to separate out the larger particles in a flow from the smaller particles in such a way that both sizes of particles are available for sampling. A jet of particle-laden air is accelerated toward a collection probe so that a small gap exists between the acceleration nozzle and the probe. A vacuum is applied to deflect a major portion of the airstream away form the collection probe. Particles larger than a certain size have sufficient momentum so that they cross the deflected streamlines and enter the collection probe, whereas smaller particles follow the deflected streamlines. The result is that the collection probe will contain a higher concentration of larger particles than is in the initial airstream. Typically, virtual impactors are high-flow devices used to separate out particles greater than several microns in diameter. We have developed a special virtual impactor to concentrate aerosol particles of diameters between 0.5 to 1 micron for the purpose of calibrating the optical cavity ring-down instrument [1]. No similar virtual impactors are commercially available. In our design, we have exploited considerations described earlier [2-4]. Performance of our virtual impactor was evaluated in an experimental set-up using TSI 3076 nebulizer and TSI 3936 scanning mobility particle size spectrometer. Under experimental conditions optimized for the best performance of the virtual impactor, we were able to concentrate the 700-nm polystyrene particles no less than 15-fold. However, under experimental conditions optimized for calibrating our cavity ring-down instrument, a concentration factor attainable was from 4 to 5. During calibration experiments, maximum realized particle number densities were 190, 300 and 1600 cm-3 for the 900-nm, 700-nm and 500-nm spheres, respectively. This paper discusses the design of the impactor and laboratory studies verifying its performance. References: 1. A.W. Strawa, R. Castaneda, T. Owano, D.S. Baer

  18. Hydrolysis of organonitrate functional groups in aerosol particles

    SciTech Connect

    Liu, Shang; Shilling, John E.; Song, Chen; Hiranuma, Naruki; Zaveri, Rahul A.; Russell, Lynn M.

    2012-10-19

    Organonitrate (ON) groups are important substituents in secondary organic aerosols. Model simulations and laboratory studies indicate a large fraction of ON groups in aerosol particles, but much lower quantities are observed in the atmosphere. Hydrolysis of ON groups in aerosol particles has been proposed recently. To test this hypothesis, we simulated formation of ON molecules in a reaction chamber under a wide range of relative humidity (0% to 90%). The mass fraction of ON groups (5% to 20% for high-NOx experiments) consistently decreased with increasing relative humidity, which was best explained by hydrolysis of ON groups at a rate of 4 day-1 (lifetime of 6 hours) for reactions under relative humidity greater than 20%. In addition, we found that secondary nitrogen-containing molecules absorb light, with greater absorption under dry and high-NOx conditions. This work provides the first evidence for particle-phase hydrolysis of ON groups, a process that could substantially reduce ON group concentration in the atmosphere.

  19. Composition and Particle Size Retrievals for Homogeneous Binary Aerosols

    NASA Astrophysics Data System (ADS)

    Niedziela, R. F.; Argon, P.; Bejcek, L.

    2014-12-01

    Tropospheric aerosols have widely varying compositions, shapes, and sizes. The ability to measure these physical characteristics, coupled with knowledge about their optical properties, can provide insight as to how these particles might participate in atmospheric processes, including their interaction with light. Over the past several years, our laboratory has been involved in developing methods to determine basic physical properties of laboratory-generated particles based on the analysis of infrared extinction spectra of multi-component aerosols. Here we report the results of a complete study on the applicability of well-known refractive index mixing rules to homogeneous binary liquid organic aerosols in an effort to yield in situ measurements of particle size and composition. In particular, we present results for terpenoid (carvone/nopinone) and long-chain hydrocarbon (squalane/squalene) mixtures. The included image shows model carvone/nopinone extinction spectra that were computed using the Lorentz-Lorenz mixing rule on complex refractive index data for the pure components.

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

    NASA Astrophysics Data System (ADS)

    Ehn, M.; Petäjä, T.; Aufmhoff, H.; Aalto, P.; Hämeri, K.; Arnold, F.; Laaksonen, A.; Kulmala, M.

    2006-10-01

    Freshly formed atmospheric aerosol particles are neither large enough to efficiently scatter incoming solar radiation nor able to act as cloud condensation nuclei. As the particles grow larger, their hygroscopicity determines the limiting size after which they are important in both of the aforementioned processes. The condensing species resulting in growth alter the hygroscopicity of the particles. We have measured hygroscopic growth of aerosol particles present in a boreal forest, along with the very hygroscopic atmospheric trace gas sulfuric acid. The focus was on days with new particle formation by nucleation. The measured hygroscopic growth factors (GF) correlated positively with gaseous phase sulfuric acid concentrations. This correlation had a strong size dependency; the smaller the particle, the more condensing sulfuric acid is bound to alter the GF due to initially smaller mass. In addition, water uptake of nucleation mode particles was monitored during new particle formation events and followed during their growth to Aitken mode sizes. As the modal diameter increased, the solubility of the particles decreased. This indicated that initially more hygroscopic particles transformed into less hygroscopic or even hydrophobic particles. A similar behavior was seen also during days with no particle formation, with GF decreasing during the evenings and increasing during early morning. This can be tentatively explained by day- and nighttime differences in the hygroscopicity of condensable vapors.

  1. The contribution of aerosol hygroscopic growth to the modeled aerosol radiative effect

    NASA Astrophysics Data System (ADS)

    Kokkola, Harri; Kühn, Thomas; Kirkevåg, Alf; Romakkaniemi, Sami; Arola, Antti

    2016-04-01

    The hygroscopic growth of atmospheric aerosols can have a significant effect on the direct radiative effect of atmospheric aerosol. However, there are significant uncertainties concerning how much of the radiative forcing is due to different chemical compounds, especially water. For example, modeled optical depth of water in global aerosol-climate models varies by more than a factor of two. These differences can be attributed to differences in modeled 1) hygroscopicity, 2) ambient relative humidity, and/or 3) aerosol size distribution. In this study, we investigate which of these above-mentioned factors cause the largest variability in the modeled optical depth of water. In order to do this, we have developed a tool that calculates aerosol extinction using interchangeable global 3D data of aerosol composition, relative humidity, and aerosol size distribution fields. This data is obtained from models that have taken part in the open international initiative AeroCom (Aerosol Comparisons between Observations and Models). In addition, we use global 3D data for relative humidity from the Atmospheric Infrared Sounder (AIRS) flying on board NASA's Aqua satellite and the National Centers for Environmental Prediction (NCEP) reanalysis data. These observations are used to evaluate the modeled relative humidity fields. In the first stage of the study, we made a detailed investigation using the aerosol-chemistry-climate model ECHAM-HAMMOZ in which most of the aerosol optical depth is caused by water. Our results show that the model significantly overestimates the relative humidity over the oceans while over land, the overestimation is lower or it is underestimated. Since this overestimation occurs over the oceans, the water optical depth is amplified as the hygroscopic growth is very sensitive to changes in high relative humidities. Over land, error in modeled relative humidity is unlikely to cause significant errors in water optical depth as relative humidities are generally

  2. Copper aerosols inhibit phytoplankton growth in the Mediterranean Sea

    PubMed Central

    Jordi, Antoni; Basterretxea, Gotzon; Tovar-Sánchez, Antonio; Alastuey, Andrés; Querol, Xavier

    2012-01-01

    Aerosol deposition plays an important role in climate and biogeochemical cycles by supplying nutrients to the open ocean, in turn stimulating ocean productivity and carbon sequestration. Aerosol particles also contain elements such as copper (Cu) that are essential in trace amounts for phytoplankton physiology but that can be toxic at high concentrations. Although the toxicity of Cu associated with aerosols has been demonstrated in bioassay experiments, extrapolation of these laboratory results to natural conditions is not straightforward. This study provides observational evidence of the negative effect of aerosols containing high Cu concentrations on marine phytoplankton over a vast region of the western Mediterranean Sea. Direct aerosol measurements were combined with satellite observations, resulting in the detection of significant declines in phytoplankton biomass after atmospheric aerosol events characterized by high Cu concentrations. The declines were more evident during summer, when nanoflagellates predominate in the phytoplankton population and stratification and oligotrophic conditions prevail in the study region. Together with previous findings concerning atmospheric Cu deposition, these results demonstrate that the toxicity of Cu-rich aerosols can involve large areas of the world’s oceans. Moreover, they highlight the present vulnerability of oceanic ecosystems to Cu-rich aerosols of anthropogenic origins. Because anthropogenic emissions are increasing, large-scale negative effects on marine ecosystems can be anticipated. PMID:23236141

  3. Physical and Optical/Radiative Characteristics of Aerosol and Cloud Particles in Tropical Cirrus: Importance in Radiation Balance

    NASA Technical Reports Server (NTRS)

    Pueschel, R. F.; Howard, S. D.; Foster, T. C.; Hallett, J.; Arnott, W. P.; Condon, Estelle P. (Technical Monitor)

    1996-01-01

    Whether cirrus clouds heat or cool the Earth-atmosphere system depends on the relative importance of the cloud shortwave albedo effect and the cloud thermal greenhouse effect. Both are determined by the distribution of ice condensate with cloud particle size. The microphysics instrument package flown aboard the NASA DC-8 in TOGA/COARE included an ice crystal replicator, a 2D Greyscale Cloud Particle Probe and a Forward Scattering Spectrometer Aerosol Probe. In combination, the electro-optical instruments permitted particle size measurements between 0.5 micrometer and 2.6 millimeter diameter. Ice crystal replicas were used to validate signals from the electrooptical instruments. Both optical and scanning electron microscopy were utilized to analyze aerosol and ice particle replicas between 0.1 micrometer and several 100 micrometer diameter. In first approximation, the combined aerosol-cloud particle spectrum in several clouds followed a power law N alpha D(sup -2.5). Thus, large cloud particles carried most of the condensate mass, while small cloud and aerosol particles determined the surface area. The mechanism of formation of small particles is growth of (hygroscopic, possibly ocean-derived) aerosol particles along the Kohler curves. The concentration of small particles is higher and less variable in space and time, and their tropospheric residence time is longer, than those of large cloud particles because of lower sedimentation velocities. Small particles shift effective cloud particle radii to sizes much smaller than the mean diameter of the cloud particles. This causes an increase in shortwave reflectivity and IR emissivity, and a decrease in transmissivity. Occasionally, the cloud reflectivity increased with altitude (decreasing temperature) stronger than did cloud emissivity, yielding enhanced radiative cooling at higher altitudes. Thus, cirrus produced by deep convection in the tropics may be critical in controlling processes whereby energy from warm

  4. Graphical techniques for interpreting the composition of individual aerosol particles

    NASA Astrophysics Data System (ADS)

    Yuan, Hui; Rahn, Kenneth A.; Zhuang, Guoshun

    A graphical technique that uses X- Y and ternary plots is presented for interpreting elemental data for individual aerosol particles. By revealing the multiple functional relationships between the elements, it offers more insight into the groups of particles and the transitions between them than traditional techniques such as factor analysis and cluster analysis alone are able to. For a sample of dust storm aerosol from Beijing in March 2002, X-Y plots revealed areas, lines, and "dots" that represented clays, smooth transitions to asymptotes of pure single-component minerals, and pure minor minerals or special particles, respectively. Ternary plots further revealed ratios of elements and potential minerals. Careful use of cluster analysis revealed subgroups of particles that were not separated by clear borders. The dust storm had three major components, clay/quartz (Al 2O 3, SiO 2, etc.), basic calcium (CaO, CaCO 3), and salts (sulfate, phosphate, chloride). Some sulfates, including CaSO 4 and (NH 4) xH 2-xSO 4, were mixed with the quartz and clay. A five-step sequence that combines graphics, basic statistics, cluster analysis, and SEM photography seems to extract the maximum information from suites of single particles.

  5. Time evolution and emission factors of aerosol particles from day and night time savannah fires

    NASA Astrophysics Data System (ADS)

    Vakkari, Ville; Beukes, Johan Paul; Tiitta, Petri; Venter, Andrew; Jaars, Kerneels; Josipovic, Miroslav; van Zyl, Pieter; Kulmala, Markku; Laakso, Lauri

    2013-04-01

    The largest uncertainties in the current global climate models originate from aerosol particle effects (IPCC, 2007) and at the same time aerosol particles also pose a threat to human health (Pope and Dockery, 2006). In southern Africa wild fires and prescribed burning are one of the most important sources of aerosol particles, especially during the dry season from June to September (e.g. Swap et al., 2003; Vakkari et al., 2012). The aerosol particle emissions from savannah fires in southern Africa have been studied in several intensive campaigns such as SAFARI 1992 and 2000 (Swap et al., 2003). However, all previous measurements have been carried out during the daytime, whereas most of the prescribed fires in southern Africa are lit up only after sunset. Furthermore, the previous campaigns followed the plume evolution for up to one hour after emission only. In this study, combining remote sensing fire observations to ground-based long-term measurements of aerosol particle and trace gas properties at the Welgegund measurement station (www.welgegund.org), we have been able to follow the time evolution of savannah fire plumes up to several hours in the atmosphere. For the first time the aerosol particle size distribution measurements in savannah fire plumes cover both day and night time plumes and also the ultrafine size range below 100 nm. During the period from May 20th 2010 to April 15th 2012 altogether 61 savannah fire plumes were observed at Welgegund. The evolution of the aerosol size distribution remained rapid for at least five hours after the fire: during this period the growth rate of the aerosol particle count mean diameter (size range 12 to 840 nm) was 24 nm h-1 for daytime plumes and 8 nm h-1 for night time plumes. The difference in the day and night time growth rate shows that photochemical reactions significantly increase the condensable vapour concentration in the plume. Furthermore, the condensable vapour concentration was found to affect both the

  6. Particle Property Data Quality Flags for the MISR Aerosol Product

    NASA Astrophysics Data System (ADS)

    Gaitley, B. J.; Kahn, R. A.; Garay, M. J.

    2012-12-01

    The MISR instrument aboard the NASA Earth Observing System's Terra satellite has the unique capability to retrieve aerosol properties under favorable conditions. General aerosol type retrieval quality guidelines are provided in the MISR Data Quality Statement and related publications. Here we report on the steps we are taking to provide an aerosol-type data quality flag, to be provided with each individual retrieval result. Some factors affecting retrieval quality that can be assessed pre-retrieval are the number of cameras available, the range of scattering angles and surface conditions such as shallow water or seasonal coastal runoff. Factors that must be assessed post-retrieval include low values of retrieved optical depth and the number and type of mixtures successfully passing the MISR algorithm acceptance criteria. Regional monthly plots with MISR measurements binned at 0.5 degree resolution with color-coded stratification of one or more parameters is the main method for identifying locations and times where particle properties are retrieved. Individual MISR values such as mid-visible AOD, number and type of mixtures passing, number of cameras used, the range and maximum scattering angles are plotted individually or as joint distributions. Initially, thresholds and conditions are determined for each MISR parameter separately. Finally, MISR parameters are combined for a given month and region, with their thresholds, to show the overall quality of the retrieval for determining particle properties. Multi-month summaries for more than twelve years of MISR data will aid in assessing quality. Seasons and regions that regularly show poorly constrained aerosol type results are identified, as are times and places where particle property information can be used with confidence. This work is performed in part at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration and in part at the NASA

  7. The Arctic polar stratospheric cloud aerosol - Aircraft measurements of reactive nitrogen, total water, and particles

    NASA Technical Reports Server (NTRS)

    Kawa, S. R.; Fahey, D. W.; Kelly, K. K.; Dye, J. E.; Baumgardner, D.; Gandrud, B. W.; Loewenstein, M.; Ferry, G. V.; Chan, K. R.

    1992-01-01

    In situ aircraft measurements in the lower stratosphere are used to investigate the reactive nitrogen, NO(y), total water, and particle components of the polar stratospheric cloud (PSC) aerosol in the Arctic. The results are compared to findings from the Antarctic derived using similar measurements and interpretive techniques. The Arctic data show that particle volume well above background values is present at temperatures above the frostpoint, confirming the result from the Antarctic that the observed PSCs are not water ice particles. NO(y) measurements inside a PSC are enhanced above ambient values consistent with anisokinetic sampling of particles containing NO(y). In the Arctic data over long segments of several flights, calculations show saturation with respect to nitric acid trihydrate without significant PSC particle growth above background.

  8. Measurements of Primary Biogenic Aerosol Particles with an Ultraviolet Aerodynamic Particle Sizer (UVAPS) During AMAZE-08

    NASA Astrophysics Data System (ADS)

    Wollny, A. G.; Garland, R.; Pöschl, U.

    2008-12-01

    Biogenic aerosols are ubiquitous in the Earth's atmosphere and they influence atmospheric chemistry and physics, the biosphere, climate, and public health. They play an important role in the spread of biological organisms and reproductive materials, and they can cause or enhance human, animal, and plant diseases. Moreover, they influence the Earth's energy budget by scattering and absorbing radiation, and they can initiate the formation of clouds and precipitation as cloud condensation and ice nuclei. The composition, abundance, and origin of biogenic aerosol particles and components are, however, still not well understood and poorly quantified. Prominent examples of primary biogenic aerosol particles, which are directly emitted from the biosphere to the atmosphere, are pollen, bacteria, fungal spores, viruses, and fragments of animals and plants. During the AMazonian Aerosol CharacteriZation Experiment (AMAZE-08) a large number of aerosol and gas-phase measurements were taken on a remote site close to Manaus, Brazil, during a period of five weeks in February and March 2008. The presented study is focused on data from an ultraviolet aerodynamic particle sizer (UVAPS, TSI inc.) that has been deployed for the first time in Amazonia. In this instrument, particle counting and aerodynamic sizing over the range of 0.5-20 μm are complemented by the measurement of UV fluorescence at 355 nm (excitation) and 420-575 nm (emission), respectively. Fluorescence at these wavelengths is characteristic for reduced pyridine nucleotides (e.g., NAD(P)H) and for riboflavin, which are specific for living cells. Thus particles exhibiting fluorescence signals can be regarded as 'viable aerosols' or 'fluorescent bioparticles' (FBAP), and their concentration can be considered as lower limit for the actual abundance of primary biogenic aerosol particles. First data analyses show a pronounced peak of FBAP at diameters around 2-3 μm. In this size range the biogenic particle fraction was

  9. Individual Aerosol Particle Types Produced by Savanna Burning

    NASA Astrophysics Data System (ADS)

    Posfai, M.; Simonics, R.; Li, J.; Hobbs, P. V.; Buseck, P. R.; Buseck, P. R.

    2001-12-01

    We used analytical transmission electron microscopy (TEM) to study individual aerosol particles that were collected on the University of Washington Convair-580 research aircraft over southern Africa during the Safari2000 Dry Season Experiment. Our goals were to study the compositions, morphologies, and mixing states of carbonaceous particles, in order to better understand the physical and chemical properties of biomass smoke on the individual-particle level. The compositions of single particles were determined using energy-dispersive x-ray spectrometry (EDS) and electron energy-loss spectroscopy (EELS). Energy-loss maps obtained with the TEM are useful for studying the spatial distribution of light elements such as carbon within the particles; thus, they provide a detailed picture of complex particles. Carbonaceous particles were assigned into three main groups on the basis of morphology and composition: "organic particles with inorganic inclusions," "tar balls," and "soot." Soot is recognized by its characteristic morphology and microstructure. The distinction between "organic particles with inorganic inclusions" and "tar balls" is somewhat arbitrary, since the two criteria that are used for their distinction (composition and aspect ratio) change continually. The relative concentrations of the three major particle types vary with the type of fire and distance from fire. In the plume of a smoldering fire west of Beria (August 31) the relative concentration of tar balls increased with aging of the plume. Tar balls have a fairly narrow size distribution with a maximum between 100 and 200 nm (diameter). The inorganic K-salt inclusions (KCl, K2SO4, KNO3) within "organic particles" should make these particles hygroscopic, regardless of the properties of the organic compounds. Aging causes the conversion of KCl into K2SO4, KNO3. Aerosol production from flaming and smoldering fires was compared over Kruger National Park on August 17; more soot and more Cl-rich inclusions

  10. Tying Biological Activity to Changes in Sea Spray Aerosol Chemical Composition via Single Particle Analyses

    NASA Astrophysics Data System (ADS)

    Sultana, C. M.; Lee, C.; Collins, D. B.; Axson, J. L.; Laskina, O.; Grandquist, J. R.; Grassian, V. H.; Prather, K. A.

    2014-12-01

    In remote marine environments, sea spray aerosols (SSA) often represent the greatest aerosol burden, thus having significant impacts on direct radiative interactions and cloud processes. Previous studies have shown that SSA is a complex mixture of inorganic salts and an array of dissolved and particulate organic components. Enrichment of SSA organic content is often correlated to seawater chlorophyll concentrations, a measure of oceanic biological activity. As the physical and chemical properties of aerosols control their radiative effects, recent studies conducted by the Center for Aerosol Impacts on Climate and the Environment have endeavored to further elucidate the ties between marine biological activity and primary SSA chemical composition using highly time resolved single particle analyses. A series of experiments performed in the recently developed Marine Aerosol Reference Tank evaluated the effect of changing marine microbial populations on SSA chemical composition, which was monitored via an aerosol time-of-flight mass spectrometer and a variety of offline spectroscopic and microscopic techniques. Each experiment was initiated using unfiltered and untreated seawater, thus maintaining a high level of biogeochemical complexity. This study is the first of its kind to capture daily changes in the primary SSA mixing state over the growth and death of a natural phytoplankton bloom. Increases in organic aerosol types (0.4-3 μm), internally and externally mixed with sea salt, could not be correlated to chlorophyll concentrations. Maximum production of these populations occurred two to four days after the in vivo chlorophyll fluorescence peaked in intensity. This work is in contrast to the current paradigm of correlating SSA organic content to seawater chlorophyll concentration.

  11. A Robust Computational Method for Coupled Liquid-liquid Phase Separation and Gas-particle Partitioning Predictions of Multicomponent Aerosols

    NASA Astrophysics Data System (ADS)

    Zuend, A.; Di Stefano, A.

    2014-12-01

    Providing efficient and reliable model predictions for the partitioning of atmospheric aerosol components between different phases (gas, liquids, solids) is a challenging problem. The partitioning of water, various semivolatile organic components, inorganic acids, bases, and salts, depends simultaneously on the chemical properties and interaction effects among all constituents of a gas + aerosol system. The effects of hygroscopic particle growth on the water contents and physical states of potentially two or more liquid and/or solid aerosol phases in turn may significantly affect multiphase chemistry, the direct effect of aerosols on climate, and the ability of specific particles to act as cloud condensation or ice nuclei. Considering the presence of a liquid-liquid phase separation in aerosol particles, which typically leads to one phase being enriched in rather hydrophobic compounds and the other phase enriched in water and dissolved electrolytes, adds a high degree of complexity to the goal of predicting the gas-particle partitioning of all components. Coupled gas-particle partitioning and phase separation methods are required to correctly account for the phase behaviour of aerosols exposed to varying environmental conditions, such as changes to relative humidity. We present new theoretical insights and a substantially improved algorithm for the reliable prediction of gas-particle partitioning at thermodynamic equilibrium based on the Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model. We introduce a new approach for the accurate prediction of the phase distribution of multiple inorganic ions between two liquid phases, constrained by charge balance, and the coupling of the liquid-liquid equilibrium model to a robust gas-particle partitioning algorithm. Such coupled models are useful for exploring the range of environmental conditions leading to complete or incomplete miscibility of aerosol constituents which will affect

  12. Radial inhomogeneities in particle composition of single, levitated aerosol particles observed by Mie resonance spectroscopy (Invited)

    NASA Astrophysics Data System (ADS)

    Krieger, U. K.; Steimer, S.; Lienhard, D.; Bastelberger, S.

    2013-12-01

    Recent observations have indicated that organic aerosol particles in the atmosphere may exist in an amorphous semi-solid or even solid (i.e. glassy) state, e.g. [1]. The influence of highly viscous and glassy states on the timescale of aerosol particle equilibration with respect to water vapor have been investigated for some model systems of atmospheric aerosol, e.g. [2,3]. In particular, it has been shown that the kinetics of the water absorption/desorption process is controlled entirely by liquid-phase diffusion of water molecules for a highly viscous aerosol particle. A liquid phase diffusion model based on numerically solving the non-linear diffusion equation predicts strong internal gradients in water concentration when condensed phase diffusion impedes the water uptake from the gas phase [2]. Here we observe and quantify the internal concentration gradients in single, levitated, micron size aerosol particles of aqueous MBTCA (3-methyl-1,2,3-Butanetricarboxylic acid) and shikimic acid using elastic Mie resonance spectroscopy. A single, aqueous particle is levitated in an electro-dynamic balance (for details see [2]), dried for several days at room temperature, cooled to the target temperature and exposed to a rapid change in relative humidity. In addition to measuring the elastically backscattered light of a 'white light ' LED source and recording the full spectrum with a spectrograph as in [2], we use a tunable diode laser (TDL) to scan high resolution TE- and TM spectra. This combination allows observing various Mie resonance mode orders simultaneously. Since we perform the experiment at low temperatures and low humidities the changes in the Mie-spectra due to water uptake are sufficiently slow to resolve the kinetics. Experimental Mie resonance spectra are inverted to concentration profiles of water within the particle by applying the numerical diffusion model [2] in conjunction with Mie calculations of multilayered spheres [4]. Potential implications for

  13. Atmospheric Condensational Properties of Ultrafine Chain and Fractal Aerosol Particles

    NASA Technical Reports Server (NTRS)

    Marlow, William H.

    1997-01-01

    The purpose for the research sponsored by this grant was to lay the foundations for qualitative understanding and quantitative description of the equilibrium vapor pressure of water vapor over the irregularly shaped, carbonaceous particles that are present in the atmosphere. This work apparently was the first systematic treatment of the subject. Research was conducted in two complementary components: 1. Calculations were performed of the equilibrium vapor pressure of water over particles comprised of aggregates of spheres in the 50-200 nm radius range. The purposes of this work were two-fold. First, since no systematic treatment of this subject had previously been conducted, its availability would be directly useful for quantitative treatment for a limited range of atmospheric aerosols. Second, it would provide qualitative indications of the effects of highly irregular particle shape on equilibrium vapor pressure of aggregates comprised of smaller spheres.

  14. Susceptibility of Tribolium confusum (Coleoptera: Tenebrionidae) to pyrethrin aerosol: effects of aerosol particle size, concentration, and exposure conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A series of laboratory studies were conducted to assess effect of droplet size on efficacy of pyrethrin aerosol against adults of Tribolium confusum Jacqueline DuVal, the confused flour beetle. A vertical flow aerosol exposure chamber that generated a standardized particle size diameter was used for...

  15. Size distribution dynamics reveal particle-phase chemistry in organic aerosol formation

    NASA Astrophysics Data System (ADS)

    Shiraiwa, M.; Yee, L. D.; Schilling, K.; Loza, C. L.; Craven, J. S.; Zuend, A.; Ziemann, P. J.; Seinfeld, J.

    2013-12-01

    Organic aerosols are ubiquitous in the atmosphere and play a central role in climate, air quality and public health. The aerosol size distribution is key in determining its optical properties and cloud condensation nucleus activity. The dominant portion of organic aerosol is formed through gas-phase oxidation of volatile organic compounds, so-called secondary organic aerosol (SOA). Typical experimental measurements of SOA formation include total SOA mass and atomic oxygen-to-carbon ratio. These measurements, alone, are generally insufficient to reveal the extent to which condensed-phase reactions occur in conjunction with the multi-generation gas-phase photooxidation. Combining laboratory chamber experiments and kinetic gas-particle modeling for the dodecane SOA system, here we show that the presence of particle-phase chemistry is reflected in the evolution of the SOA size distribution as well as its mass concentration. Particle-phase reactions are predicted to occur mainly at the particle surface and the reaction products contribute more than half of the SOA mass. Chamber photooxidation with a mid-experiment aldehyde injection confirms that heterogeneous reaction of aldehydes with organic hydroperoxides forming peroxyhemiacetals can lead to a large increase in SOA mass. The results of the current work have a number of implications for SOA models. While the dynamics of an aerosol size distribution reflects the mechanism of growth, we demonstrate here that it provides a key constraint in interpreting laboratory and ambient SOA formation. This work, although carried out specifically for the long chain alkane, dodecane, is expected to be widely applicable to other major classes of SOA precursors. SOA consists of a myriad of organic compounds containing various functional groups, which can generally undergo heterogeneous/multiphase reactions forming low-volatility products such as oligomers and other high molecular mass compounds. If particle-phase chemistry is indeed

  16. A New Electrospray Aerosol Generator with High Particle Transmission Efficiency.

    PubMed

    Fu, Huijing; Patel, Anand C; Holtzman, Michael J; Chen, Da-Ren

    2011-01-01

    A new single-capillary electrospray (ES) aerosol generator has been developed for monodisperse particle production with maximal transmission efficiency. The new generator consists of both a spray chamber in a point-to-orifice-plate configuration and a charge reduction chamber that can hold up to 4 Nuclespot ionizers (Model P-2042, NRD Inc.). The 2 chambers are partitioned by an orifice plate. To optimize the particle transmission efficiency of the prototype, a systematic study was performed on the generator by varying the system setup and operation. Two key dimensions of the generator setup, the orifice diameter and the distance from the capillary tip to the orifice plate, were varied. Fluorescence analysis was applied to characterize the loss of ES-generated particles at different locations of the prototype. It was found that particle loss in the generator could be reduced by either increasing the orifice diameter or decreasing the distance between the capillary tip and the orifice plate. Increasing either the total radioactivity of the ionizers or the flowrate of the particle carrier gas also further decreased the particle loss in the system. The maximum particle transmission efficiency of 88.0% was obtained with the spray chamber fully opened to the charge reduction chamber, the capillary tip at the same level as the orifice plate, and 4 bipolar ionizers installed.

  17. A method to resolve the phase state of aerosol particles

    NASA Astrophysics Data System (ADS)

    Saukko, E.; Kuuluvainen, H.; Virtanen, A.

    2012-01-01

    The phase state of atmospheric aerosols has an impact on their chemical aging and their deliquescence and thus their ability to act as cloud condensation nuclei (CCN). The phase change of particles can be induced by the deliquescence or efflorescence of water or by chemical aging. Existing methods, such as tandem differential mobility analysis rely on the size change of particles related to the water uptake or release. To address the need to study the phase change induced by mass-preserving and nearly mass-preserving processes a new method has been developed. The method relies on the physical impaction of particles on a smooth substrate and subsequent counting of bounced particles by a condensation particle counter (CPC). The connection between the bounce probability and physical properties of particles is so far qualitative. To evaluate the performance of this method, the phase state of ammonium sulfate and levoglucosan, crystalline and amorphous solid, in the presence of water vapor was studied. The results show a marked difference in particle bouncing properties between substances - not only at the critical relative humidity level, but also on the slope of the bouncing probability with respect to humidity. This suggests that the method can be used to differentiate between amorphous and crystalline substances as well as to differentiate between liquid and solid phases.

  18. A method to resolve the phase state of aerosol particles

    NASA Astrophysics Data System (ADS)

    Saukko, E.; Kuuluvainen, H.; Virtanen, A.

    2011-10-01

    The phase state of atmospheric aerosols has impact on their chemical aging and their deliquescence and thus their ability to act as cloud condensation nuclei (CCN). The phase change of particles can be induced by the deliquescence or efflorescence of water or by chemical aging. Existing methods, such as tandem differential mobility analysis rely on the size change of particles related to the water uptake or release related to deliquescence and efflorescence. To address the need to study the phase change induced by mass-preserving and nearly mass-preserving processes a new method has been developed. The method relies on the physical impaction of particles on a smooth substrate and subsequent counting of bounced particles by condensation particle counter (CPC). The connection between the bounce probability and physical properties of particles is so far qualitative. To evaluate the performance of this method, the phase state of ammonium sulfate and levoglucosan, crystalline and amorphous solid, in the presence of water vapor was studied. The results show a marked difference in particle bouncing properties between substances - not only at the critical relative humidity level, but also on the slope of the bouncing probability with respect to humidity. This suggests that the method can be used to differentiate between amorphous and crystalline substances as well as to differentiate between liquid and solid phases.

  19. Method and apparatus for aerosol particle absorption spectroscopy

    DOEpatents

    Campillo, Anthony J.; Lin, Horn-Bond

    1983-11-15

    A method and apparatus for determining the absorption spectra, and other properties, of aerosol particles. A heating beam source provides a beam of electromagnetic energy which is scanned through the region of the spectrum which is of interest. Particles exposed to the heating beam which have absorption bands within the band width of the heating beam absorb energy from the beam. The particles are also illuminated by light of a wave length such that the light is scattered by the particles. The absorption spectra of the particles can thus be determined from an analysis of the scattered light since the absorption of energy by the particles will affect the way the light is scattered. Preferably the heating beam is modulated to simplify the analysis of the scattered light. In one embodiment the heating beam is intensity modulated so that the scattered light will also be intensity modulated when the particles absorb energy. In another embodiment the heating beam passes through an interferometer and the scattered light reflects the Fourier Transform of the absorption spectra.

  20. A New Electrospray Aerosol Generator with High Particle Transmission Efficiency.

    PubMed

    Fu, Huijing; Patel, Anand C; Holtzman, Michael J; Chen, Da-Ren

    2011-01-01

    A new single-capillary electrospray (ES) aerosol generator has been developed for monodisperse particle production with maximal transmission efficiency. The new generator consists of both a spray chamber in a point-to-orifice-plate configuration and a charge reduction chamber that can hold up to 4 Nuclespot ionizers (Model P-2042, NRD Inc.). The 2 chambers are partitioned by an orifice plate. To optimize the particle transmission efficiency of the prototype, a systematic study was performed on the generator by varying the system setup and operation. Two key dimensions of the generator setup, the orifice diameter and the distance from the capillary tip to the orifice plate, were varied. Fluorescence analysis was applied to characterize the loss of ES-generated particles at different locations of the prototype. It was found that particle loss in the generator could be reduced by either increasing the orifice diameter or decreasing the distance between the capillary tip and the orifice plate. Increasing either the total radioactivity of the ionizers or the flowrate of the particle carrier gas also further decreased the particle loss in the system. The maximum particle transmission efficiency of 88.0% was obtained with the spray chamber fully opened to the charge reduction chamber, the capillary tip at the same level as the orifice plate, and 4 bipolar ionizers installed. PMID:22829715

  1. Inhomogeneities in particle composition of single, levitated aerosol particles observed by Mie resonance spectroscopy

    NASA Astrophysics Data System (ADS)

    Krieger, Ulrich; Lienhard, Daniel; Bastelberger, Sandra; Steimer, Sarah

    2014-05-01

    Recent observations have indicated that organic aerosol particles in the atmosphere may exist in an amorphous semi-solid or even solid (i.e. glassy) state, e.g. [1]. The influence of highly viscous and glassy states on the timescale of aerosol particle equilibration with respect to water vapor have been investigated for some model systems of atmospheric aerosol, e.g. [2,3]. In particular, it has been shown that the kinetics of the water absorption/desorption process is controlled entirely by liquid-phase diffusion of water molecules for a highly viscous aerosol particle. A liquid phase diffusion model based on numerically solving the non-linear diffusion equation predicts strong internal gradients in water concentration when condensed phase diffusion impedes the water uptake from the gas phase [2]. Here we observe and quantify the internal concentration gradients in single, levitated, micron size aerosol particles of aqueous shikimic acid using elastic Mie resonance spectroscopy. A single, aqueous particle is levitated in an electro-dynamic balance (for details see [2]), dried for several days at room temperature, cooled to the target temperature and exposed to a rapid change in relative humidity. In addition to measuring the elastically backscattered light of a "white light" LED source and recording the full spectrum with a spectrograph as in [2], we use a tunable diode laser (TDL) to scan high resolution TE- and TM spectra. This combination allows observing various Mie resonance mode orders simultaneously. Since we perform the experiment at low temperatures and low humidities the changes in the Mie-spectra due to water uptake are sufficiently slow to resolve the kinetics. Experimental Mie resonance spectra are inverted to concentration profiles of water within the particle by applying the numerical diffusion model [2] in conjunction with Mie calculations of multilayered spheres [4]. [1] A. Virtanen et al. (2010): An amorphous solid state of biogenic secondary

  2. Morphology and Optical Properties of Mixed Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Fard, Mehrnoush M.; Krieger, Ulrich; Rudich, Yinon; Marcolli, Claudia; Peter, Thomas

    2016-04-01

    Experiments and modeling studies have shown that deliquesced aerosols can exist not only as one-phase system containing organics, inorganic salts and water, but often as two-phase systems consisting of a predominantly organic and a predominantly inorganic aqueous phase (1,2). Recent laboratory studies conducted with model mixtures representing tropospheric aerosols (1,2,3), secondary organic aerosol (SOA) from smog chamber experiments (4), and field measurements (5) suggest that liquid-liquid phase separations (LLPS) is indeed a common phenomenon in mixed organic/ inorganic particles. During LLPS, particles may adopt different morphologies mainly core-shell and partially engulfed. A core-shell configuration will have consequences for heterogeneous chemistry and hygroscopicity and as a result will alter the optical properties of the particles in particular for organic phases containing absorbing molecules, e.g. brown carbon. The primary objective of this project is to establish a method for investigating the morphology of mixed inorganic and absorbing organic compounds of atmospheric relevance and study their radiative properties before, during, and after phase transitions mainly during LLPS. This will be the first study looking into the radiative effect of LLPS in detail. Our ternary model system consist of ammonium sulfate (AS)/ Polyethylene Glycol (PEG)/ and water (H2O). Carminic acid (CA) was added as a proxy for an absorbing organic compound to the system. The behavior of single droplets of above ternary mixture was monitored during relative humidity (RH) cycles using optical microscopy. The same ternary mixture particle was levitated in an electrodynamic balance (EDB) and the change in its absorption properties was measured at varying RH. In addition, Mie-code modeling is used to predict the absorption efficiency of the same ternary system and the result will be compared with the data obtained from EDB experiment. We also intend to determine the occurrence of

  3. Gas uptake and chemical aging of semisolid organic aerosol particles.

    PubMed

    Shiraiwa, Manabu; Ammann, Markus; Koop, Thomas; Pöschl, Ulrich

    2011-07-01

    Organic substances can adopt an amorphous solid or semisolid state, influencing the rate of heterogeneous reactions and multiphase processes in atmospheric aerosols. Here we demonstrate how molecular diffusion in the condensed phase affects the gas uptake and chemical transformation of semisolid organic particles. Flow tube experiments show that the ozone uptake and oxidative aging of amorphous protein is kinetically limited by bulk diffusion. The reactive gas uptake exhibits a pronounced increase with relative humidity, which can be explained by a decrease of viscosity and increase of diffusivity due to hygroscopic water uptake transforming the amorphous organic matrix from a glassy to a semisolid state (moisture-induced phase transition). The reaction rate depends on the condensed phase diffusion coefficients of both the oxidant and the organic reactant molecules, which can be described by a kinetic multilayer flux model but not by the traditional resistor model approach of multiphase chemistry. The chemical lifetime of reactive compounds in atmospheric particles can increase from seconds to days as the rate of diffusion in semisolid phases can decrease by multiple orders of magnitude in response to low temperature or low relative humidity. The findings demonstrate that the occurrence and properties of amorphous semisolid phases challenge traditional views and require advanced formalisms for the description of organic particle formation and transformation in atmospheric models of aerosol effects on air quality, public health, and climate.

  4. Aerosolization Characteristics of Dry Powder Inhaler Formulations for the Excipient Enhanced Growth (EEG) Application: Effect of Spray Drying Process Conditions on Aerosol Performance

    PubMed Central

    Son, Yoen-Ju; Longest, P. Worth; Hindle, Michael

    2013-01-01

    The aim of this study was to develop a spray dried submicrometer powder formulation suitable for the excipient enhanced growth (EEG) application. Combination particles were prepared using the Buchi Nano spray dryer B-90. A number of spray drying and formulation variables were investigated with the aims of producing dry powder formulations that were readily dispersed upon aerosolization and maximizing the fraction of submicrometer particles. Albuterol sulfate, mannitol, L-leucine, and poloxamer 188 were selected as a model drug, hygroscopic excipient, dispersibility enhancer and surfactant, respectively. Formulations were assessed by scanning electron microscopy and aerosol performance following aerosolization using an Aerolizer® dry powder inhaler (DPI). In vitro drug deposition was studied using a realistic mouth-throat (MT) model. Based on the in vitro aerosolization results, the best performing submicrometer powder formulation consisted of albuterol sulfate, mannitol, L-leucine and poloxamer 188 in a ratio of 30:48:20:2, containing 0.5% solids in a water:ethanol (80:20% v/v) solution which was spray dried at 70 °C. The submicrometer particle fraction (FPF1μm/ED) of this final formulation was 28.3% with more than 80% of the capsule contents being emitted during aerosolization. This formulation also showed 4.1% MT deposition. The developed combination formulation delivered a powder aerosol developed for the EEG application with high dispersion efficiency and low MT deposition from a convenient DPI device platform. PMID:23313343

  5. Method for determining aerosol particle size device for determining aerosol particle size

    DOEpatents

    Novick, Vincent J.

    1998-01-01

    A method for determining the mass median diameter D of particles contained in a fluid is provided wherein the data of the mass of a pre-exposed and then a post-exposed filter is mathematically combined with data concerning the pressure differential across the same filter before and then after exposure to a particle-laden stream. A device for measuring particle size is also provided wherein the device utilizes the above-method for mathematically combining the easily quantifiable data.

  6. Linking variations in sea spray aerosol particle hygroscopicity to composition during two microcosm experiments

    NASA Astrophysics Data System (ADS)

    Forestieri, Sara D.; Cornwell, Gavin C.; Helgestad, Taylor M.; Moore, Kathryn A.; Lee, Christopher; Novak, Gordon A.; Sultana, Camille M.; Wang, Xiaofei; Bertram, Timothy H.; Prather, Kimberly A.; Cappa, Christopher D.

    2016-07-01

    The extent to which water uptake influences the light scattering ability of marine sea spray aerosol (SSA) particles depends critically on SSA chemical composition. The organic fraction of SSA can increase during phytoplankton blooms, decreasing the salt content and therefore the hygroscopicity of the particles. In this study, subsaturated hygroscopic growth factors at 85 % relative humidity (GF(85 %)) of predominately submicron SSA particles were quantified during two induced phytoplankton blooms in marine aerosol reference tanks (MARTs). One MART was illuminated with fluorescent lights and the other was illuminated with sunlight, referred to as the "indoor" and "outdoor" MARTs, respectively. Optically weighted GF(85 %) values for SSA particles were derived from measurements of light scattering and particle size distributions. The mean optically weighted SSA diameters were 530 and 570 nm for the indoor and outdoor MARTs, respectively. The GF(85 %) measurements were made concurrently with online particle composition measurements, including bulk composition (using an Aerodyne high-resolution aerosol mass spectrometer) and single particle (using an aerosol time-of-flight mass spectrometer) measurement, and a variety of water-composition measurements. During both microcosm experiments, the observed optically weighted GF(85 %) values were depressed substantially relative to pure inorganic sea salt by 5 to 15 %. There was also a time lag between GF(85 %) depression and the peak chlorophyll a (Chl a) concentrations by either 1 (indoor MART) or 3-to-6 (outdoor MART) days. The fraction of organic matter in the SSA particles generally increased after the Chl a peaked, also with a time lag, and ranged from about 0.25 to 0.5 by volume. The observed depression in the GF(85 %) values (relative to pure sea salt) is consistent with the large observed volume fractions of non-refractory organic matter (NR-OM) comprising the SSA. The GF(85 %) values exhibited a reasonable negative

  7. SAGE II aerosol validation: selected altitude measurements, including particle micromeasurements.

    PubMed

    Oberbeck, V R; Livingston, J M; Russell, P B; Pueschel, R F; Rosen, J N; Osborn, M T; Kritz, M A; Snetsinger, K G; Ferry, G V

    1989-06-20

    Correlative aerosol measurements taken at a limited number of altitudes during coordinated field experiments are used to test the validity of particulate extinction coefficients derived from limb path solar radiance measurements taken by the Stratospheric Aerosol and Gas Experiment (SAGE) II Sun photometer. In particular, results are presented from correlative measurement missions that were conducted during January 1985, August 1985, and July 1986. Correlative sensors included impactors, laser spectrometers, and filter samplers aboard an U-2-airplane, an upward pointing lidar aboard a P-3 airplane, and balloon-borne optical particle counters (dustsondes). The main body of this paper focuses on the July 29, 1986, validation experiment, which minimized the many difficulties (e.g., spatial and temporal inhomogeneities, imperfect coincidences) that can complicate the validation process. On this day, correlative aerosol measurements taken at an altitude of 20.5 km agreed with each other within their respective uncertainties, and particulate extinction values calculated at SAGE II wavelengths from these measurements validated corresponding SAGE II values. Additional validation efforts on days when measurement and logistical conditions were much less favorable for validation are discussed in an appendix.

  8. Experimental Determination of Chemical Diffusion within Secondary Organic Aerosol Particles

    SciTech Connect

    Abramson, Evan H.; Imre, D.; Beranek, Josef; Wilson, Jacqueline; Zelenyuk, Alla

    2013-02-28

    Formation, properties, transformations, and temporal evolution of secondary organic aerosols (SOA) particles strongly depend on particle phase. Recent experimental evidence from a number of groups indicates that SOA is in a semi-solid phase, the viscosity of which remained unknown. We find that when SOA is made in the presence of vapors of volatile hydrophobic molecules the SOA particles absorb and trap them. Here, we illustrate that it is possible to measure the evaporation rate of these molecules that is determined by their diffusion in SOA, which is then used to calculate a reasonably accurate value for the SOA viscosity. We use pyrene as a tracer molecule and a-pinene SOA as an illustrative case. It takes ~24 hours for half the pyrene to evaporate to yield a viscosity of 10^8 Pa s for a-pinene. This viscosity is consistent with measurements of particle bounce and evaporation rates. We show that viscosity of 10^8 Pa s implies coalescence times of minutes, consistent with the findings that SOA particles are spherical. Similar measurements on aged SOA particles doped with pyrene yield a viscosity of 10^9 Pa s, indicating that hardening occurs with time, which is consistent with observed decrease in water uptake and evaporation rate with aging.

  9. EVALUATION OF ACOUSTIC FORCES ON A PARTICLE IN AEROSOL MEDIUM

    SciTech Connect

    Lee, S; Richard Dimenna, R

    2007-09-27

    The acoustic force exerted on a solid particle was evaluated to develop a fundamental understanding of the critical physical parameters or constraints affecting particle motion and capture in a collecting device. The application of an acoustic force to the collection of a range of submicron-to-micron particles in a highly turbulent airflow stream laden with solid particles was evaluated in the presence of other assisting and competing forces. This scoping estimate was based on the primary acoustic force acting directly on particles in a dilute aerosol system, neglecting secondary interparticle effects such as agglomeration of the sub-micron particles. A simplified analysis assuming a stable acoustic equilibrium with an infinite sound speed in the solid shows that for a solid-laden air flow in the presence of a standing wave, particles will move toward the nearest node. The results also show that the turbulent drag force on a 1-{micro}m particle resulting from eddy motion is dominant when compared with the electrostatic force or the ultrasonic acoustic force. At least 180 dB acoustic pressure level at 1 MHz is required for the acoustic force to be comparable to the electrostatic or turbulent drag forces in a high-speed air stream. It is noted that particle size and pressure amplitude are dominant parameters for the acoustic force. When acoustic pressure level becomes very large, the acoustic energy will heat up the surrounding air medium, which may cause air to expand. With an acoustic power of about 600 watts applied to a 2000-lpm air flow, the air temperature can increase by as much as 15 C at the exit of the collector.

  10. Morphological characterization of soot aerosol particles during LACIS Experiment in November (LExNo)

    NASA Astrophysics Data System (ADS)

    Kiselev, A.; Wennrich, C.; Stratmann, F.; Wex, H.; Henning, S.; Mentel, T. F.; Kiendler-Scharr, A.; Schneider, J.; Walter, S.; Lieberwirth, I.

    2010-06-01

    Combined mobility and aerodynamic measurements were used to characterize the morphology of soot particles in an experimental campaign on the hygroscopic growth and activation of an artificial biomass burning aerosol. A custom-made, single-stage low-pressure impactor and two aerosol mass spectrometers (AMS) operating in the free molecular regime were used to measure the vacuum aerodynamic diameter of mobility-selected artificial soot particles that were produced in a spark discharge generator and then modified by condensation of ammonium hydrogen sulfate or levoglucosan as a coating to change their hydroscopic activity. Transmission electron microscope images revealed a relationship between the electrical mobility diameter and the diameter of the enveloping sphere, thus enabling evaluation of the effective density of soot agglomerates. A fractal description of the morphology of the soot aggregates allowed for evaluation of the average mass of the hygroscopic material per particle. The average mass of the hygroscopic material per particle was also measured directly with the two AMS instruments, and the agreement between the two methods was found satisfactory. This tandem approach allows detection of small changes in the particle effective density and morphology caused by condensation of organic material.

  11. Method for determining aerosol particle size, device for determining aerosol particle size

    DOEpatents

    Novick, V.J.

    1998-10-06

    A method for determining the mass median diameter D of particles contained in a fluid is provided wherein the data of the mass of a pre-exposed and then a post-exposed filter is mathematically combined with data concerning the pressure differential across the same filter before and then after exposure to a particle-laden stream. A device for measuring particle size is also provided wherein the device utilizes the above-method for mathematically combining the easily quantifiable data. 2 figs.

  12. Dynamics of Aerosol Particles in Stationary, Isotropic Turbulence

    NASA Technical Reports Server (NTRS)

    Collins, Lance R.; Meng, Hui

    2004-01-01

    A detailed study of the dynamics of sub-Kolmogorov-size aerosol particles in stationary isotropic turbulence has been performed. The study combined direct numerical simulations (DNS; directed by Prof. Collins) and high-resolution experimental measurements (directed by Prof. Meng) under conditions of nearly perfect geometric and parametric overlap. The goal was to measure the accumulation of particles in low-vorticity regions of the flow that arises from the effect commonly referred to as preferential concentration. The grant technically was initiated on June 13, 2000; however, funding was not available until July 11, 2000. The grant was originally awarded to Penn State University (numerical simulations) and SUNY-Buffalo (experiments); however, Prof. Collins effort was moved to Cornell University on January 2002 when he joined that university. He completed the study there. A list of the specific tasks that were completed under this study is presented.

  13. Multiphase OH oxidation kinetics of organic aerosol: The role of particle phase state and relative humidity

    NASA Astrophysics Data System (ADS)

    Slade, Jonathan H.; Knopf, Daniel A.

    2014-07-01

    Organic aerosol can exhibit different phase states in response to changes in relative humidity (RH), thereby influencing heterogeneous reaction rates with trace gas species. OH radical uptake by laboratory-generated levoglucosan and methyl-nitrocatechol particles, serving as surrogates for biomass burning aerosol, is determined as a function of RH. Increasing RH lowers the viscosity of amorphous levoglucosan aerosol particles enabling enhanced OH uptake. Conversely, OH uptake by methyl-nitrocatechol aerosol particles is suppressed at higher RH as a result of competitive coadsorption of H2O that occupies reactive sites. This is shown to have substantial impacts on organic aerosol lifetimes with respect to OH oxidation. The results emphasize the importance of organic aerosol phase state to accurately describe the multiphase chemical kinetics and thus chemical aging process in atmospheric models to better represent the evolution of organic aerosol and its role in air quality and climate.

  14. Water nucleation properties of chaparral fire aerosol particles

    SciTech Connect

    Hudson, J.G.; Rogers, C.F.; Hallett, J.

    1989-05-01

    In December, 1986, planned and prescribed forest management burns took place at Lodi Canyon, on the north side of the Los Angeles Basin, California. These fires involved a mixture of species of small trees and shrubs, including scrub oak, chamise, and mountain mahogany, known collectively as ''chaparral'' in the Western US. Over a period of about two weeks, about 200 hectares of chaparral were consumed. This prescribed burn presented an opportunity for three days of airborne measurements of aerosol properties including total particle or condensation nuclei (CN) concentrations and cloud condensation nuclei (CCN) concentrations. This study is in coordination with other efforts conducted simultaneously; here the emphasis will be on the airborne CN and CCN measurements and on related studies conducted on a laboratory scale. In this study, we distinguish between CCN and the total aerosol particle population as gauged by the CN count. CCN and CN concentrations and CCN/CN ratios will be presented for the airborne measurements and for laboratory measurements employing a similar fuel. Ancillary ion chromatography (IC) and scanning electron microscopy (SEM) information will also be presented for the laboratory-scale chaparral burn. 11 refs., 4 figs., 4 tabs.

  15. Real-Time Detection Method And System For Identifying Individual Aerosol Particles

    DOEpatents

    Gard, Eric Evan; Fergenson, David Philip

    2005-10-25

    A method and system of identifying individual aerosol particles in real time. Sample aerosol particles are compared against and identified with substantially matching known particle types by producing positive and negative test spectra of an individual aerosol particle using a bipolar single particle mass spectrometer. Each test spectrum is compared to spectra of the same respective polarity in a database of predetermined positive and negative spectra for known particle types and a set of substantially matching spectra is obtained. Finally the identity of the individual aerosol particle is determined from the set of substantially matching spectra by determining a best matching one of the known particle types having both a substantially matching positive spectrum and a substantially matching negative spectrum associated with the best matching known particle type.

  16. Hygroscopicity of internally mixed multi-component aerosol particles of atmospheric relevance

    NASA Astrophysics Data System (ADS)

    Liu, Qifan; Jing, Bo; Peng, Chao; Tong, Shengrui; Wang, Weigang; Ge, Maofa

    2016-01-01

    The hygroscopic properties of two water-soluble organic compounds (WSOCs) relevant to urban haze pollution (phthalic acid and levoglucosan) and their internally mixtures with inorganic salts (ammonium sulfate and ammonium nitrate) are investigated using a hygroscopicity tandem differential mobility analyzer (H-TDMA) system. The multi-component particles uptake water gradually in the range 5-90% relative humidity (RH). The experimental results are compared with the thermodynamic model predictions. For most mixtures, Extended Aerosol Inorganic Model (E-AIM) predictions agree well with the measured growth factors. The hygroscopic growth of mixed particles can be well described by the Zdanovskii-Stokes-Robinson (ZSR) relation as long as the mixed particles are completely liquid. ZSR calculations underestimate the water uptake of mixed particles at moderate RH due to the partial dissolution of ammonium sulfate in the organic and ammonium nitrate solution in this RH region. The phase of ammonium nitrate in the initial dry particles changes dramatically with the composition of mixtures. The presence of organics in the mixed particles can inhibit the crystallization of ammonium nitrate during the drying process and results in water uptake at low RH (RH < 60%). These results demonstrate that certain representative WSOCs can substantially influence the hygroscopicity of inorganic salts and overall water uptake of particles.

  17. Polluted dust promotes new particle formation and growth

    PubMed Central

    Nie, Wei; Ding, Aijun; Wang, Tao; Kerminen, Veli-Matti; George, Christian; Xue, Likun; Wang, Wenxing; Zhang, Qingzhu; Petäjä, Tuukka; Qi, Ximeng; Gao, Xiaomei; Wang, Xinfeng; Yang, Xiuqun; Fu, Congbin; Kulmala, Markku

    2014-01-01

    Understanding new particle formation and their subsequent growth in the troposphere has a critical impact on our ability to predict atmospheric composition and global climate change. High pre-existing particle loadings have been thought to suppress the formation of new atmospheric aerosol particles due to high condensation and coagulation sinks. Here, based on field measurements at a mountain site in South China, we report, for the first time, in situ observational evidence on new particle formation and growth in remote ambient atmosphere during heavy dust episodes mixed with anthropogenic pollution. Both the formation and growth rates of particles in the diameter range 15–50 nm were enhanced during the dust episodes, indicating the influence of photo-induced, dust surface-mediated reactions and resulting condensable vapor production. This study provides unique in situ observations of heterogeneous photochemical processes inducing new particle formation and growth in the real atmosphere, and suggests an unexpected impact of mineral dust on climate and atmospheric chemistry. PMID:25319109

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

    NASA Astrophysics Data System (ADS)

    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

  19. Dynamics of aerosol size during inhalation: hygroscopic growth of commercial nebulizer formulations.

    PubMed

    Haddrell, Allen E; Davies, James F; Miles, Rachael E H; Reid, Jonathan P; Dailey, Lea Ann; Murnane, Darragh

    2014-03-10

    The size of aerosol particles prior to, and during, inhalation influences the site of deposition within the lung. As such, a detailed understanding of the hygroscopic growth of an aerosol during inhalation is necessary to accurately model the deposited dose. In the first part of this study, it is demonstrated that the aerosol produced by a nebulizer, depending on the airflows rates, may experience a (predictable) wide range of relative humidity prior to inhalation and undergo dramatic changes in both size and solute concentration. A series of sensitive single aerosol analysis techniques are then used to make measurements of the relative humidity dependent thermodynamic equilibrium properties of aerosol generated from four common nebulizer formulations. Measurements are also reported of the kinetics of mass transport during the evaporation or condensation of water from the aerosol. Combined, these measurements allow accurate prediction of the temporal response of the aerosol size prior to and during inhalation. Specifically, we compare aerosol composed of pure saline (150 mM sodium chloride solution in ultrapure water) with two commercially available nebulizer products containing relatively low compound doses: Breath®, consisting of a simple salbutamol sulfate solution (5 mg/2.5 mL; 1.7 mM) in saline, and Flixotide® Nebules, consisting of a more complex stabilized fluticasone propionate suspension (0.25 mg/mL; 0.5 mM in saline. A mimic of the commercial product Tobi© (60 mg/mL tobramycin and 2.25 mg/mL NaCl, pH 5.5-6.5) is also studied, which was prepared in house. In all cases, the presence of the pharmaceutical was shown to have a profound effect on the magnitude, and in some cases the rate, of the mass flux of water to and from the aerosol as compared to saline. These findings provide physical chemical evidence supporting observations from human inhalation studies, and suggest that using the growth dynamics of a pure saline aerosol in a lung inhalation model

  20. Dynamics of aerosol size during inhalation: hygroscopic growth of commercial nebulizer formulations.

    PubMed

    Haddrell, Allen E; Davies, James F; Miles, Rachael E H; Reid, Jonathan P; Dailey, Lea Ann; Murnane, Darragh

    2014-03-10

    The size of aerosol particles prior to, and during, inhalation influences the site of deposition within the lung. As such, a detailed understanding of the hygroscopic growth of an aerosol during inhalation is necessary to accurately model the deposited dose. In the first part of this study, it is demonstrated that the aerosol produced by a nebulizer, depending on the airflows rates, may experience a (predictable) wide range of relative humidity prior to inhalation and undergo dramatic changes in both size and solute concentration. A series of sensitive single aerosol analysis techniques are then used to make measurements of the relative humidity dependent thermodynamic equilibrium properties of aerosol generated from four common nebulizer formulations. Measurements are also reported of the kinetics of mass transport during the evaporation or condensation of water from the aerosol. Combined, these measurements allow accurate prediction of the temporal response of the aerosol size prior to and during inhalation. Specifically, we compare aerosol composed of pure saline (150 mM sodium chloride solution in ultrapure water) with two commercially available nebulizer products containing relatively low compound doses: Breath®, consisting of a simple salbutamol sulfate solution (5 mg/2.5 mL; 1.7 mM) in saline, and Flixotide® Nebules, consisting of a more complex stabilized fluticasone propionate suspension (0.25 mg/mL; 0.5 mM in saline. A mimic of the commercial product Tobi© (60 mg/mL tobramycin and 2.25 mg/mL NaCl, pH 5.5-6.5) is also studied, which was prepared in house. In all cases, the presence of the pharmaceutical was shown to have a profound effect on the magnitude, and in some cases the rate, of the mass flux of water to and from the aerosol as compared to saline. These findings provide physical chemical evidence supporting observations from human inhalation studies, and suggest that using the growth dynamics of a pure saline aerosol in a lung inhalation model

  1. Cassini CAPS-ELS observations of carbon-based anions and aerosol growth in Titan's ionosphere

    NASA Astrophysics Data System (ADS)

    Desai, Ravindra; Coates, Andrew; Wellbrock, Anne; Kataria, Dhiren; Jones, Geraint; Lewis, Gethyn; Waite, J.

    2016-06-01

    Cassini observations of Titans ionosphere revealed an atmosphere rich in positively charged ions with masses up to > 350 amu and negatively charged ions and aerosols with mass over charge ratios as high as 13,800 amu/q. The detection of negatively charged molecules by the Cassini CAPS Electron Spectrometer (CAPS-ELS) was particularly surprising and showed how the synthesis of large aerosol-size particles takes place at altitudes much greater than previously thought. Here, we present further analysis into this CAPS-ELS dataset, through an enhanced understanding of the instrument's response function. In previous studies the intrinsic E/E energy resolution of the instrument did not allow specific species to be identified and the detections were classified into broad mass ranges. In this study we use an updated fitting procedure to show how the ELS mass spectrum can be resolved into specific peaks at multiples of carbon-based anions up to > 100 amu/q. The negatively charged ions and aerosols in Titans ionosphere increase in mass with decreasing altitude, the lightest species being observed close to Titan's exobase of ˜1,450km and heaviest species observed at altitudes < 950km. We identify key stages in this apparent growth process and report on key intermediaries which appear to trigger the rapid growth of the larger aerosol-size particles.

  2. The effect of local sources on particle size and chemical composition and their role in aerosol-cloud interactions

    NASA Astrophysics Data System (ADS)

    Portin, H.; Leskinen, A.; Hao, L.; Kortelainen, A.; Miettinen, P.; Jaatinen, A.; Laaksonen, A.; Lehtinen, K. E. J.; Romakkaniemi, S.; Komppula, M.

    2013-12-01

    The effects of local pollutant sources and particle chemical composition on aerosol-cloud interactions were investigated by measuring cloud interstitial and total aerosol size distributions, particle chemical composition and hygroscopic growth factors and cloud droplet size distributions on an observation tower, with a special focus on comparing clean air masses with those affected by local sources. The polluted air masses contained more particles than the clean air masses in all size classes, excluding the accumulation mode. This was caused by cloud processing, which was also observed for the polluted air but to a lesser extent. Some, mostly minor, differences in the particle chemical composition between the air masses were observed. The average size and number concentration of activating particles were quite similar for both air masses, producing average droplet populations with only minor distinctions. As a case study, a long cloud event was analyzed in detail regarding emissions from local sources, including a paper mill and a heating plant. Clear differences in the total and accumulation mode particle concentrations, particle hygroscopicity and chemical composition during the cloud event were observed. Particularly, larger particles, higher hygroscopicities and elevated amounts of inorganic constituents, especially SO4, were linked with the pollutant plumes. In the air masses affected by traffic and domestic wood combustion, a bimodal particle hygroscopicity distribution was observed, indicating externally mixed aerosol. The variable conditions during the event had a clear impact on cloud droplet formation.

  3. Reformulating atmospheric aerosol thermodynamics and hygroscopic growth into fog, haze and clouds

    NASA Astrophysics Data System (ADS)

    Metzger, S.; Lelieveld, J.

    2007-06-01

    Modeling atmospheric aerosol and cloud microphysics is rather complex, even if chemical and thermodynamical equilibrium is assumed. We show, however, that the thermodynamics can be considerably simplified by reformulating equilibrium to consistently include water, and transform laboratory-based concepts to atmospheric conditions. We generalize the thermodynamic principles that explain hydration and osmosis - merely based on solute solubilities - to explicitly account for the water mass consumed by hydration. As a result, in chemical and thermodynamical equilibrium the relative humidity (RH) suffices to determine the saturation molality, including solute and solvent activities (and activity coefficients), since the water content is fixed by RH for a given aerosol concentration and type. As a consequence, gas/liquid/solid aerosol equilibrium partitioning can be solved analytically and non-iteratively. Our new concept enables an efficient and accurate calculation of the aerosol water mass and directly links the aerosol hygroscopic growth to fog, haze and cloud formation. We apply our new concept in the 3rd Equilibrium Simplified Aerosol Model (EQSAM3) for use in regional and global chemistry-transport and climate models. Its input is limited to the species' solubilities from which a newly introduced stoichiometric coefficient for water is derived. Analogously, we introduce effective stoichiometric coefficients for the solutes to account for complete or incomplete dissociation. We show that these coefficients can be assumed constant over the entire activity range and calculated for various inorganic, organic and non-electrolyte compounds, including alcohols, sugars and dissolved gases. EQSAM3 calculates the aerosol composition and gas/liquid/solid partitioning of mixed inorganic/organic multicomponent solutions and the associated water uptake for almost 100 major compounds. It explicitly accounts for particle hygroscopic growth by computing aerosol properties such as

  4. Control over hygroscopic growth of saline aqueous aerosol using Pluronic polymer additives.

    PubMed

    Haddrell, Allen E; Hargreaves, Graham; Davies, James F; Reid, Jonathan P

    2013-02-25

    The hygroscopic properties of an aerosol originating from a nebulizer solution can affect the extent of peripheral deposition within the respiratory tract, which in turn affects drug efficacy of drugs delivered to the lungs. Thus, the ability to tailor the degree and rate of hygroscopic growth of an aerosol produced by a nebulizer through modification of the formulation would serve to improve drug efficacy through targeted lung deposition. In this study, the kinetic and thermodynamic hygroscopic properties of sodium chloride aerosol mixed with commercially available Pluronic polymers, specifically F77 and F127, are reported using three complementary single aerosol analysis techniques, specifically aerosol optical tweezers, a double ring electrodynamic balance and a concentric cylinder electrodynamic balance. The F77 polymer is shown to have a predictable effect on the hygroscopic properties of the aerosol: the ability of the droplet to uptake water from the air depends on the solute weight percent of sodium chloride present in a linear dose dependant manner. Unlike the smaller F77, a non-linear relationship was observed for the larger molecular weight F127 polymer, with significant suppression of hygroscopic growth (>50% by mass) for solution aerosol containing even only 1 wt% of the polymer and 99 wt% sodium chloride. The suppression of growth is shown to be consistent with the formation of mixed phase aerosol particles containing hydrophilic inorganic rich domains and hydrophobic polymer rich domains that sequester some of the inorganic component, with the two phases responding to changes in relative humidity independently. This independence of coupling with the gas phase is apparent in both the equilibrium state and the kinetics of water evaporation/condensation. By starting with a saline nebulizer solution with a concentration of F127 ∼10(-2)mM, a 12% reduction in the radius of all aerosol produced at a relative humidity (RH) of 84% is possible. The

  5. Phosphorus-bearing Aerosol Particles From Volcanic Plumes

    NASA Astrophysics Data System (ADS)

    Obenholzner, J. H.; Schroettner, H.; Poelt, P.; Delgado, H.; Caltabiano, T.

    2003-12-01

    Particles rich in P or bulk geochemical data of volcanic aerosol particles showing high P contents are known from many volcanic plumes (Stanton, 1994; Obenholzner et al., 2003). FESEM/EDS analysis of individual particles obtained from the passively degassing plume of Popocatepetl volcano, Mx. (1997) and from the plume of Stromboli (May 2003) show P frequently. Even at the high resolution of the FESEM, euhedral apatite crystals could not be observed. At Popocatepetl (1997) spherical Ca-P-O particles are common. Fluffy, fractal or botryoidal particles also can contain EDS-detectable amounts of P. The EDS spectrum of such particles can comprise various elements. However most particles show P, S and Cl. P-S and P-S-metal species are known in chemistry but do they occur in volcanic plumes? Stoichiometric considerations had been made in the past suggesting the existence of P-S species in plumes (Stanton 1994), gas sampling and remote gas monitoring systems have not detected yet such molecules in plumes. The particle spectrum of the reawakened Popocateptel volcano might be related to accumulation of volatiles at the top of a magma chamber during the phase of dormancy. P-Fe rich, Ca-free aggregates are also known from the eruption of El Chichon 1982 (SEM/EDS by M. Sheridan, per. comm. 08-24-2003). Persistently active volcanoes (i.e. Stromboli) represent a different category according to continuous degassing and aerosol particle formation. A particle collector ( ca. 90 ml/min) accompanied a COSPEC helicopter flight at Stromboli (May 15, 2003) after one of the rare types of sub-plinian events on April 5 2003. P-bearing particles are very common. For instance, an Fe oxide grain (diam. = 2 æm) is partially covered by fluffy and euhedral P-bearing matter. The elements detected are P, Cl, Na, Mg, Al, Si, K, Ca, Ti and (Fe). The fluffy and the euhedral (rhombohedral?) matter show in SE-BSE-mix image almost identical grey colors. At Stromboli and Popocatepetl particles on which

  6. Aerosol particle properties in a South American megacity

    NASA Astrophysics Data System (ADS)

    Ulke, Ana; Torres-Brizuela, Marcela; Raga, Graciela; Baumgardner, Darrel; Cancelada, Marcela

    2015-04-01

    The subtropical city of Buenos Aires is located on the western shore of Río de la Plata, on the southeastern coast of Argentina. It is the second largest metropolitan area in South America, with a population density of around 14 thousand people per km2. When all 24 counties of the Great Buenos Aires Metropolitan Area are included it is the third-largest conurbation in Latin America, with a population of around fifteen million inhabitants. The generalized worldwide trend to concentrate human activities in urban regions that continue to expand in area, threatens the local and regional environment. Air pollution in the Buenos Aires airshed is due to local sources (mainly the mobile sources, followed by the electric power plants and some industries) and to distant sources (like biomass burning, dust, marine aerosols and occasionally volcanic ash) whose products arrive in the city area due to the regional transport patterns. Previous research suggests that ambient aerosol particle concentrations should be considered an air quality problem. A field campaign was conducted in Buenos Aires in 2011 in order to characterize some aerosol particles properties measured for the first time in the city. Measurements began in mid- April and continued until December. The field observations were done in a collaborative effort between the Universities of Mexico (UNAM) and Buenos Aires (UBA). A suite of instruments was installed on the roof of an UBA laboratory and classroom buildings (34.54° S, 58.44° W) at an altitude of approximately 30 m above sea level. The measurements included the number concentration of condensation nuclei (CN) larger than approximately 50 nm, the mass concentration of particle-bound polycyclic aromatic hydrocarbons (PPAH), the scattering (Bscat) and absorption (Babs) coefficients at 550 nm and the vertical profiles of backscattered light from aerosols at a wavelength of 910 nm using a ceilometer. In addition, a weather station recorded the meteorological

  7. Review: engineering particles using the aerosol-through-plasma method

    SciTech Connect

    Phillips, Jonathan; Luhrs, Claudia C; Richard, Monique

    2009-01-01

    For decades, plasma processing of materials on the nanoscale has been an underlying enabling technology for many 'planar' technologies, particularly virtually every aspect of modern electronics from integrated-circuit fabrication with nanoscale elements to the newest generation of photovoltaics. However, it is only recent developments that suggest that plasma processing can be used to make 'particulate' structures of value in fields, including catalysis, drug delivery, imaging, higher energy density batteries, and other forms of energy storage. In this paper, the development of the science and technology of one class of plasma production of particulates, namely, aerosol-through-plasma (A-T-P), is reviewed. Various plasma systems, particularly RF and microwave, have been used to create nanoparticles of metals and ceramics, as well as supported metal catalysts. Gradually, the complexity of the nanoparticles, and concomitantly their potential value, has increased. First, unique two-layer particles were generated. These were postprocessed to create unique three-layer nanoscale particles. Also, the technique has been successfully employed to make other high-value materials, including carbon nanotubes, unsupported graphene, and spherical boron nitride. Some interesting plasma science has also emerged from efforts to characterize and map aerosol-containing plasmas. For example, it is clear that even a very low concentration of particles dramatically changes plasma characteristics. Some have also argued that the local-thermodynamic-equilibrium approach is inappropriate to these systems. Instead, it has been suggested that charged- and neutral-species models must be independently developed and allowed to 'interact' only in generation terms.

  8. Particle growth in silane-hydrogen discharges

    SciTech Connect

    Kujundzic, Damir; Gallagher, Alan

    2006-02-01

    The growth of silicon particles has been measured in silane-hydrogen radio-frequency (rf) discharges using a typical hydrogen/silane dilution ratio (20) and the pressure range (1.2-2.2 Torr) used for the production of amorphous and microcrystalline silicon films and devices. By operating brief discharges without gas flow, the particle size is obtained from the afterglow diffusion and the particle density from the scattered-light intensity. These small-reactor data thus provide the expected particle size and density versus location-in a commercial large-area-isothermal-flowing-gas reactor. Particle growth rate is a strong function of pressure, whereas film growth rate is almost independent of pressure. Both growth rates are sensitive to rf voltage, although particle growth is more sensitive.

  9. Molecular-scale evidence of aerosol particle formation via sequential addition of HIO3

    NASA Astrophysics Data System (ADS)

    Sipilä, Mikko; Sarnela, Nina; Jokinen, Tuija; Henschel, Henning; Junninen, Heikki; Kontkanen, Jenni; Richters, Stefanie; Kangasluoma, Juha; Franchin, Alessandro; Peräkylä, Otso; Rissanen, Matti P.; Ehn, Mikael; Vehkamäki, Hanna; Kurten, Theo; Berndt, Torsten; Petäjä, Tuukka; Worsnop, Douglas; Ceburnis, Darius; Kerminen, Veli-Matti; Kulmala, Markku; O'Dowd, Colin

    2016-09-01

    Homogeneous nucleation and subsequent cluster growth leads to the formation of new aerosol particles in the atmosphere. The nucleation of sulfuric acid and organic vapours is thought to be responsible for the formation of new particles over continents, whereas iodine oxide vapours have been implicated in particle formation over coastal regions. The molecular clustering pathways that are involved in atmospheric particle formation have been elucidated in controlled laboratory studies of chemically simple systems, but direct molecular-level observations of nucleation in atmospheric field conditions that involve sulfuric acid, organic or iodine oxide vapours have yet to be reported. Here we present field data from Mace Head, Ireland, and supporting data from northern Greenland and Queen Maud Land, Antarctica, that enable us to identify the molecular steps involved in new particle formation in an iodine-rich, coastal atmospheric environment. We find that the formation and initial growth process is almost exclusively driven by iodine oxoacids and iodine oxide vapours, with average oxygen-to-iodine ratios of 2.4 found in the clusters. On the basis of this high ratio, together with the high concentrations of iodic acid (HIO3) observed, we suggest that cluster formation primarily proceeds by sequential addition of HIO3, followed by intracluster restructuring to I2O5 and recycling of water either in the atmosphere or on dehydration. Our study provides ambient atmospheric molecular-level observations of nucleation, supporting the previously suggested role of iodine-containing species in the formation of new aerosol particles, and identifies the key nucleating compound.

  10. New aerosol particles formation in the Sao Paulo Metropolitan Area

    NASA Astrophysics Data System (ADS)

    Vela, Angel; Andrade, Maria de Fatima; Ynoue, Rita

    2016-04-01

    The Sao Paulo Metropolitan Area (SPMA), in the southeast region of Brazil, is considered a megalopolis comprised of Sao Paulo city and more 38 municipalities. The air pollutant emissions in the SPMA are related to the burning of the fuels: etanol, gasohol (gasoline with 25% ethanol) and diesel. According to CETESB (2013), the road vehicles contributed up to about 97, 87, and 80% of CO, VOCs and NOx emissions in 2012, respectively, being most of NOx associated to diesel combustion and most of CO and VOCs from gasohol and ethanol combustion. Studies conducted on ambient air pollution in the SPMA have shown that black carbon (BC) explains 21% of mass concentration of PM2.5 compared with 40% of organic carbon (OC), 20% of sulfates, and 12% of soil dust (Andrade et al., 2012). Most of the observed ambient PM2.5 mass concentration usually originates from precursors gases such as sulphur dioxide (SO2), ammonia (NH3), nitrogen oxides (NOx) and VOCs as well as through the physico-chemical processes such as the oxidation of low volatile hydrocarbons transferring to the condensed phase (McMurry et al., 2004). The Weather Research and Forecasting with Chemistry model (WRF-Chem; Grell et al. 2005), configured with three nested grid cells: 75, 15, and 3 km, is used as photochemical modeling to describe the physico-chemical processes leading to evolution of particles number and mass size distribution from a vehicular emission model developed by the IAG-USP laboratory of Atmospheric Processes and based on statistical information of vehicular activity. The spatial and temporal distributions of emissions in the finest grid cell are based on road density products compiled by the OpenStreetMap project and measurements performed inside tunnels in the SPMA, respectively. WRF-Chem simulation with coupled primary aerosol (dust and sea-salt) and biogenic emission modules and aerosol radiative effects turned on is conducted as the baseline simulation (Case_0) to evaluate the model

  11. Deposition flux of aerosol particles and 15 polycyclic aromatic hydrocarbons in the North China Plain.

    PubMed

    Wang, Xilong; Liu, Shuzhen; Zhao, Jingyu; Zuo, Qian; Liu, Wenxin; Li, Bengang; Tao, Shu

    2014-04-01

    The present study examined deposition fluxes of aerosol particles and 15 polycyclic aromatic hydrocarbons (PAHs) associated with the particles in the North China Plain. The annual mean deposition fluxes of aerosol particles and 15 PAHs were 0.69 ± 0.46 g/(m(2) ×d) and 8.5 ± 6.2 μg/(m(2) ×d), respectively. Phenanthrene, fluoranthene, pyrene, chrysene, benzo[b]fluoranthene, and benzo[k]fluoranthene were the dominant PAHs bound to deposited aerosol particles throughout the year. The total concentration of 15 PAHs in the deposited aerosol particles was the highest in winter but lowest in spring. The highest PAH concentration in the deposited aerosol particles in winter was because the heating processes highly increased the concentration in atmospheric aerosol particles. Low temperature and weak sunshine in winter reduced the degradation rate of deposited aerosol particle-bound PAHs, especially for those with low molecular weight. The lowest PAH concentration in deposited aerosol particles in spring resulted from the frequently occurring dust storms, which diluted PAH concentrations. The mean deposition flux of PAHs with aerosol particles in winter (16 μg/[m(2) ×d]) reached 3 times to 5 times that in other seasons (3.5-5.0 μg/[m(2) ×d]). The spatial variation of the deposition flux of PAHs with high molecular weight (e.g., benzo[a]pyrene) was consistent with their concentrations in the atmospheric aerosol particles, whereas such a phenomenon was not observed for those with low molecular weight (e.g., phenanthrene) because of their distinct hydrophobicity, Henry's law constant, and the spatially heterogeneous meteorological conditions.

  12. Experimental Assessment of Collection Efficiency of Submicron Aerosol Particles by Cloud Droplets

    NASA Astrophysics Data System (ADS)

    Huang, Y.; Ardon-Dryer, K.; Cziczo, D. J.

    2013-12-01

    The interplay between aerosol particles and water droplets in the atmosphere, especially in clouds, influences both aerosol and cloud properties. The major uncertainty in our understanding of climate arises in the indirect effect of aerosol and their ability to impact cloud formation and consequently alter the global radiative balance. The collision between a water droplet and aerosol particles that results in coalescence is termed 'collection' or 'coagulation'. Coagulation can lead to aerosol removal from the atmosphere or induce ice nucleation via contact freezing at temperatures below 0 C. Theoretical studies have shown that for aerosol particles smaller than 0.1 micrometers, Brownian motion is important, and for particles with diameters larger than 1 micrometer, inertial force dominates. There is a collection efficiency minimum for particles between 0.1-2 micrometers, called the 'Greenfield Gap'. Experimental efforts, however, have been limited to very large drizzle and rain drops until recently, and constrained parameters necessary to describe particle collection efficiency by cloud droplets have not been available. One reason is that laboratory setups that allow for coagulation to be observed on a single-particle basis have been lacking. Collection efficiency is also an important parameter for studying and assessing contact ice nucleation. Contact ice nucleation is currently the least understood ice nucleation mechanism and can be potentially important for mixed-phase cloud formation. The significance of experimentally assessing collection efficiency is therefore two-fold: to first understand the frequency of contacts and to then understand the fraction that lead to ice nucleation. We have constructed the MIT-Contact Freezing Chamber (MIT-CFC) to study collection efficiency of submicron aerosol particles by cloud droplets and contact freezing. A stream of 30-micron cloud droplets fall freely into the chamber and collide with aerosol particles. The outflow

  13. Single-particle Analyses of Compositions, Morphology, and Viscosity of Aerosol Particles Collected During GoAmazon2014

    NASA Astrophysics Data System (ADS)

    Adachi, K.; Gong, Z.; Bateman, A. P.; Martin, S. T.; Cirino, G. G.; Artaxo, P.; Sedlacek, A. J., III; Buseck, P. R.

    2014-12-01

    Single-particle analysis using transmission electron microscopy (TEM) shows composition and morphology of individual aerosol particles collected during the GoAmazon2014 campaign. These TEM results indicate aerosol types and mixing states, both of which are important for evaluating particle optical properties and cloud condensation nuclei activity. The samples were collected at the T3 site, which is located in the Amazon forest with influences from the urban pollution plume from Manaus. Samples were also collected from the T0 site, which is in the middle of the jungle with minimal to no influences of anthropogenic sources. The aerosol particles mainly originated from 1) anthropogenic pollution (e.g., nanosphere soot, sulfate), 2) biogenic emissions (e.g., primary biogenic particles, organic aerosols), and 3) long-range transport (e.g., sea salts). We found that the biogenic organic aerosol particles contain homogeneously distributed potassium. Particle viscosity is important for evaluating gas-particle interactions and atmospheric chemistry for the particles. Viscosity can be estimated from the rebounding behavior at controlled relative humidities, i.e., highly viscous particles display less rebound on a plate than low-viscosity particles. We collected 1) aerosol particles from a plate (non-rebounded), 2) those that had rebounded from the plate and were then captured onto an adjacent sampling plate, and 3) particles from ambient air using a separate impactor sampler. Preliminary results show that more than 90% of non-rebounded particles consisted of nanosphere soot with or without coatings. The coatings mostly consisted of organic matter. Although rebounded particles also contain nanosphere soot (number fraction 64-69%), they were mostly internally mixed with sulfate, organic matter, or their mixtures. TEM tilted images suggested that the rebounded particles were less deformed on the substrate, whereas the non-rebounded particles were more deformed, which could

  14. Impact of gas-to-particle partitioning approaches on the simulated radiative effects of biogenic secondary organic aerosol

    NASA Astrophysics Data System (ADS)

    Scott, C. E.; Spracklen, D. V.; Pierce, J. R.; Riipinen, I.; D'Andrea, S. D.; Rap, A.; Carslaw, K. S.; Forster, P. M.; Kulmala, M.; Mann, G. W.; Pringle, K. J.

    2015-02-01

    The oxidation of biogenic volatile organic compounds (BVOCs) gives a range of products, from semi-volatile to extremely low-volatility compounds. To treat the interaction of these secondary organic vapours with the particle phase, global aerosol microphysics models generally use either a thermodynamic partitioning approach (assuming instant equilibrium between semi-volatile oxidation products and the particle phase) or a kinetic approach (accounting for the size-dependence of condensation). We show that model treatment of the partitioning of biogenic organic vapours into the particle phase, and consequent distribution of material across the size distribution, controls the magnitude of the first aerosol indirect effect (AIE) due to biogenic secondary organic aerosol (SOA). With a kinetic partitioning approach, SOA is distributed according to the existing condensation sink, enhancing the growth of the smallest particles, i.e., those in the nucleation mode. This process tends to increase cloud droplet number concentrations in the presence of biogenic SOA. By contrast, a thermodynamic approach distributes SOA according to pre-existing organic mass, restricting the growth of the smallest particles, limiting the number that are able to form cloud droplets. With an organically medicated new particle formation mechanism, applying a thermodynamic rather than a kinetic approach reduces our calculated global mean AIE due to biogenic SOA by 24%. Our results suggest that the mechanisms driving organic partitioning need to be fully understood in order to accurately describe the climatic effects of SOA.

  15. Impact of gas-to-particle partitioning approaches on the simulated radiative effects of biogenic secondary organic aerosol

    NASA Astrophysics Data System (ADS)

    Scott, C. E.; Spracklen, D. V.; Pierce, J. R.; Riipinen, I.; D'Andrea, S. D.; Rap, A.; Carslaw, K. S.; Forster, P. M.; Artaxo, P.; Kulmala, M.; Rizzo, L. V.; Swietlicki, E.; Mann, G. W.; Pringle, K. J.

    2015-11-01

    The oxidation of biogenic volatile organic compounds (BVOCs) gives a range of products, from semi-volatile to extremely low-volatility compounds. To treat the interaction of these secondary organic vapours with the particle phase, global aerosol microphysics models generally use either a thermodynamic partitioning approach (assuming instant equilibrium between semi-volatile oxidation products and the particle phase) or a kinetic approach (accounting for the size dependence of condensation). We show that model treatment of the partitioning of biogenic organic vapours into the particle phase, and consequent distribution of material across the size distribution, controls the magnitude of the first aerosol indirect effect (AIE) due to biogenic secondary organic aerosol (SOA). With a kinetic partitioning approach, SOA is distributed according to the existing condensation sink, enhancing the growth of the smallest particles, i.e. those in the nucleation mode. This process tends to increase cloud droplet number concentrations in the presence of biogenic SOA. By contrast, an approach that distributes SOA according to pre-existing organic mass restricts the growth of the smallest particles, limiting the number that are able to form cloud droplets. With an organically mediated new particle formation mechanism, applying a mass-based rather than a kinetic approach to partitioning reduces our calculated global mean AIE due to biogenic SOA by 24 %. Our results suggest that the mechanisms driving organic partitioning need to be fully understood in order to accurately describe the climatic effects of SOA.

  16. Aerosol mixingstate, hygroscopic growth and cloud activation efficiency during MIRAGE 2006

    SciTech Connect

    Lance, Sara; Raatikainen, T.; Onasch, Timothy B.; Worsnop, Douglas R.; Yu, Xiao-Ying; Alexander, M. L.; Stolzenberg, Mark; McMurry, Peter; Smith, James N.; Nenes, Athanasios

    2013-05-15

    Observations of aerosol hygroscopic growth and CCN activation spectra for submicron particles are reported for the T1 ground site outside of Mexico City during the MIRAGE 2006 campaign. K¨ohler theory is used to evaluate the characteristic water uptake coefficient, k*, for the CCN active aerosol population using both size-resolved HTMDA and size-resolved CCNc measurements. Organic mass fractions, (forg), are evaluated from size-resolved aerosol mass spectrometer (AMS) measurements, from which kAMS is inferred and compared against k*. Strong diurnal profiles of aerosol water uptake parameters and aerosol composition are observed. We find that new particle formation (NPF) events are correlated with an increased k* and CCN-active fraction during the daytime, with greater impact on smaller particles. During NPF events, the number concentration of 40 nm particles acting as CCN can surpass by more than a factor of two the concentrations of 100 nm particles acting as CCN, at supersaturations of 0.51% +/- 0.06%. We also find that at 0600-0800 in the morning throughout the campaign, fresh traffic emissions result in substantial changes to the chemical distribution of the aerosol, with on average 65% externally-mixed fraction for 40 nm particles and 30% externally-mixed fraction for 100 nm particles, whereas at midday nearly all particles of both sizes can be described as “internally-mixed”. Average activation spectra and growth factor distributions are analyzed for different time periods characterizing the daytime (with and without NPF events), the early morning “rush hour”, and the entire campaign. We show that k* derived from CCNc measurements decreases as a function of size during all time periods, while the CCN-active fraction increases as a function of size. Size-resolved AMS measurements do not predict the observed trend for k* versus particle size, which can be attributed to unresolved mixing-state and the presence of refractory material not measured by the

  17. Aerosol mixing-state, hygroscopic growth and cloud activation efficiency during MIRAGE 2006

    NASA Astrophysics Data System (ADS)

    Lance, S.; Raatikainen, T.; Onasch, T.; Worsnop, D. R.; Yu, X.-Y.; Alexander, M. L.; Stolzenburg, M. R.; McMurry, P. H.; Smith, J. N.; Nenes, A.

    2012-06-01

    Observations of aerosol hygroscopic growth and CCN activation spectra for submicron particles are reported for the T1 ground site outside of Mexico City during the MIRAGE 2006 campaign. κ-Köhler theory is used to evaluate the characteristic water uptake coefficient, κ*, for the CCN active aerosol population using both size-resolved HTDMA and size-resolved CCNc measurements. Organic mass fractions, forg, are evaluated from size-resolved aerosol mass spectrometer (AMS) measurements, from which κAMS is inferred and compared against κ*. Strong diurnal profiles of aerosol water uptake parameters and aerosol composition are observed. We find that new particle formation (NPF) events are correlated with an increased κ* and CCN-active fraction during the daytime, with greater impact on smaller particles. During NPF events, the number concentration of 40 nm particles acting as CCN can surpass by more than a factor of two the concentrations of 100 nm particles acting as CCN, at supersaturations of 0.51% ± 0.06%. We also find that at 06:00-08:00 in the morning throughout the campaign, fresh traffic emissions result in substantial changes to the chemical distribution of the aerosol, with on average 65% externally-mixed fraction for 40 nm particles and 30% externally-mixed fraction for 100 nm particles, whereas at midday nearly all particles of both sizes can be described as internally-mixed. Average activation spectra and growth factor distributions are analyzed for different time periods characterizing the daytime (with and without NPF events), the early morning "rush hour", and the entire campaign. We show that κ* derived from CCNc measurements decreases as a function of size during all time periods, while the CCN-active fraction increases as a function of size. Size-resolved AMS measurements do not predict the observed trend for κ* versus particle size, which can be attributed to unresolved mixing-state and the presence of refractory material not measured by the AMS

  18. A combined particle trap/HTDMA hygroscopicity study of mixed inorganic/organic aerosol particles

    NASA Astrophysics Data System (ADS)

    Zardini, A. A.; Sjogren, S.; Marcolli, C.; Krieger, U. K.; Gysel, M.; Weingartner, E.; Baltensperger, U.; Peter, T.

    2008-03-01

    Atmospheric aerosols are often mixtures of inorganic and organic material. Organics can represent a large fraction of the total aerosol mass and are comprised of water-soluble and insoluble compounds. Increasing attention was paid in the last decade to the capability of mixed inorganic/organic aerosol particles to take up water (hygroscopicity). We performed hygroscopicity measurements of internally mixed particles containing ammonium sulfate and carboxylic acids (citric, glutaric, adipic acid) in parallel with an electrodynamic balance (EDB) and a hygroscopicity tandem differential mobility analyzer (HTDMA). The organic compounds were chosen to represent three distinct physical states. During hygroscopicity cycles covering hydration and dehydration measured by the EDB and the HTDMA, pure citric acid remained always liquid, adipic acid remained always solid, while glutaric acid could be either. We show that the hygroscopicity of mixtures of the above compounds is well described by the Zdanovskii-Stokes-Robinson (ZSR) relationship as long as the two-component particle is completely liquid in the ammonium sulfate/citric acid and in the ammonium sulfate/glutaric acid cases. However, we observe significant discrepancies compared to what is expected from bulk thermodynamics when a solid component is present. We explain this in terms of a complex morphology resulting from the crystallization process leading to veins, pores, and grain boundaries which allow for water sorption in excess of bulk thermodynamic predictions caused by the inverse Kelvin effect on concave surfaces.

  19. Use of analytical electron microscopy for the individual particle analysis of the Arctic haze aerosol

    SciTech Connect

    Sheridan, P.J.

    1986-01-01

    To explore the usefulness of the analytical electron microscope for the analysis and source apportionment of individual aerosol particles, aerosol samples amenable to individual particle analysis were collected from a remote region. These samples were from the Arctic haze aerosol, and were collected on board a research aircraft during the Arctic Gas and Aerosol Sampling Program in spring 1983. Before elemental analysis by analytical electron microscopy (AEM) could be performed, an extensive relative sensitivity factor study was undertaken to calibrate the microscope/detector system for quanitative x-ray microanalysis. Subsequently determined elemental data, along with morphological information, were used to group the particles into classes with similar characteristics. Forty-seven classes of particles were found in the Arctic samples, the most populous classes containing H/sub 2/SO/sub 4/ droplets, carbonaceous particles, lithophilic particles, CaSO/sub 4/ or NaCl. Several classes containing anthropogenic particles were also identified.

  20. Formation of highly porous aerosol particles by atmospheric freeze-drying in ice clouds.

    PubMed

    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.

  1. Formation of highly porous aerosol particles by atmospheric freeze-drying in ice clouds

    PubMed Central

    Adler, Gabriela; Koop, Thomas; Haspel, Carynelisa; Taraniuk, Ilya; Moise, Tamar; Koren, Ilan; Heiblum, Reuven H.; Rudich, Yinon

    2013-01-01

    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. PMID:24297908

  2. Formation of highly porous aerosol particles by atmospheric freeze-drying in ice clouds.

    PubMed

    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. PMID:24297908

  3. Aerosol optical properties in the southeastern United States in summer - Part 1: Hygroscopic growth

    NASA Astrophysics Data System (ADS)

    Brock, C. A.; Wagner, N. L.; Anderson, B. E.; Attwood, A. R.; Beyersdorf, A.; Campuzano-Jost, P.; Carlton, A. G.; Day, D. A.; Diskin, G. S.; Gordon, T. D.; Jimenez, J. L.; Lack, D. A.; Liao, J.; Markovic, M. Z.; Middlebrook, A. M.; Ng, N. L.; Perring, A. E.; Richardson, M. S.; Schwarz, J. P.; Washenfelder, R. A.; Welti, A.; Xu, L.; Ziemba, L. D.; Murphy, D. M.

    2015-09-01

    Aircraft observations of meteorological, trace gas, and aerosol properties were made during May-September 2013 in the southeastern United States (US) under fair-weather, afternoon conditions with well-defined planetary boundary layer structure. Optical extinction at 532 nm was directly measured at three relative humidities and compared with extinction calculated from measurements of aerosol composition and size distribution using the κ-Köhler approximation for hygroscopic growth. Using this approach, the hygroscopicity parameter κ for the organic fraction of the aerosol must have been < 0.10 to be consistent with 75 % of the observations within uncertainties. This subsaturated κ value for the organic aerosol in the southeastern US is consistent with several field studies in rural environments. We present a new parameterization of the change in aerosol extinction as a function of relative humidity that better describes the observations than does the widely used power-law (gamma, γ) parameterization. This new single-parameter κext formulation is based upon κ-Köhler and Mie theories and relies upon the well-known approximately linear relationship between particle volume (or mass) and optical extinction (Charlson et al., 1967). The fitted parameter, κext, is nonlinearly related to the chemically derived κ parameter used in κ-Köhler theory. The values of κext we determined from airborne measurements are consistent with independent observations at a nearby ground site.

  4. Aerosol-induced mechanisms for cumulus congestus growth

    NASA Astrophysics Data System (ADS)

    Sheffield, Amanda M.; Saleeby, Stephen M.; Heever, Susan C.

    2015-09-01

    Tropical convection has been observed to contain three cloud modes, the middle of which is cumulus congestus clouds. Congestus clouds act to moisten the tropical atmosphere, may be mixed-phase, and on occasion surpass the freezing level inversion from where they may develop into deeper convection. This study investigates the impacts of enhanced aerosol concentrations on the growth of congestus clouds produced in idealized cloud-resolving model simulations run under a state of radiative convective equilibrium (RCE). High-resolution, long-duration simulations were completed using the Regional Atmospheric Modeling System (RAMS). Aerosol concentrations between 2 and 4 km above ground level were varied from clean to polluted conditions in order to represent the advection of Saharan dust over the Atlantic Ocean. The congestus populations within each aerosol simulation are statistically analyzed using 10 days of model output after the simulation reaches RCE. Results indicate that congestus in more polluted conditions produce greater amounts of cloud water and ice mass, enhanced updraft strengths, and an increase in the number of congestus cloud tops that extend above the freezing level. Enhanced vapor depositional growth on the populations of more numerous, smaller cloud droplets in the polluted conditions, and the subsequent increase in latent heat release in the warm phase regions of the cloud, is found to be important factors in convective invigoration of these cloud systems. Aerosol feedbacks associated with cold pools and condensate loading also influence the updraft strength and act in opposition to the warm phase invigoration processes.

  5. Size distribution and scattering phase function of aerosol particles retrieved from sky brightness measurements

    NASA Technical Reports Server (NTRS)

    Kaufman, Y. J.; Gitelson, A.; Karnieli, A.; Ganor, E. (Editor); Fraser, R. S.; Nakajima, T.; Mattoo, S.; Holben, B. N.

    1994-01-01

    Ground-based measurements of the solar transmission and sky radiance in a horizontal plane through the Sun are taken in several geographical regions and aerosol types: dust in a desert transition zone in Israel, sulfate particles in Eastern and Western Europe, tropical aerosol in Brazil, and mixed continental/maritime aerosol in California. Stratospheric aerosol was introduced after the eruption of Mount Pinatubo in June 1991. Therefore measurements taken before the eruption are used to analyze the properties of tropospheric aerosol; measurements from 1992 are also used to detect the particle size and concentration of stratospheric aerosol. The measurements are used to retrieve the size distribution and the scattering phase function at large scattering angles of the undisturbed aerosol particles. The retrieved properties represent an average on the entire atmospheric column. A comparison between the retrieved phase function for a scattering angle of 120 deg, with phase function predicted from the retrieved size distribution, is used to test the assumption of particle homogeneity and sphericity in radiative transfer models (Mie theory). The effect was found to be small (20% +/- 15%). For the stratospheric aerosol (sulfates), as expected, the phase function was very well predicted using the Mie theory. A model with a power law distribution, based on the spectral dependence of the optical thickness, alpha, cannot estimate accurately the phase function (up to 50% error for lambda = 0.87 microns). Before the Pinatubo eruption the ratio between the volumes of sulfate and coarse particles was very well correlated with alpha. The Pinatubo stratospheric aerosol destroyed this correlation. The aerosol optical properties are compared with analysis of the size, shape, and composition of the individual particles by electron microscopy of in situ samples. The measured volume size distribution before the injection of stratospheric aerosol consistently show two modes, sulfate

  6. Recent progress in understanding particle nucleation and growth

    PubMed Central

    Eisele, F. L.; McMurry, P. H.

    1997-01-01

    In the past half decade, several new tools have become available for investigating particle nucleation and growth. A number of joint field and laboratory studies exploiting some of these new measurement capabilities will be described and new insights shared. the ability to measure OH, SO2, H2SO4 and aerosol number and size distributions has made possible a comparison between H2SO4 production and loss onto particles in continental air masses. In regions remote from urban emissions, agreement is typically quite good. In contrast, joint field measurements of nucleation precursors such as gas phase H2SO4 and ultrafine particles suggest that classical bimolecular nucleation theory may not properly describe the tropospheric nucleation process. An alternative mechanism, possibly involving ammonia as a stabilizing agent for H2SO4/H2O molecular clusters is discussed. Finally, ultrafine particle measurements are shown to offer new opportunities for studying particle growth rates. Preliminary results suggest that in a remote continental air mass, gas phase H2SO4 uptake is far too slow to explain observed growth rates.

  7. Real-time detection method and system for identifying individual aerosol particles

    DOEpatents

    Gard, Eric E.; Coffee, Keith R.; Frank, Matthias; Tobias, Herbert J.; Fergenson, David P.; Madden, Norm; Riot, Vincent J.; Steele, Paul T.; Woods, Bruce W.

    2007-08-21

    An improved method and system of identifying individual aerosol particles in real time. Sample aerosol particles are collimated, tracked, and screened to determine which ones qualify for mass spectrometric analysis based on predetermined qualification or selection criteria. Screening techniques include one or more of determining particle size, shape, symmetry, and fluorescence. Only qualifying particles passing all screening criteria are subject to desorption/ionization and single particle mass spectrometry to produce corresponding test spectra, which is used to determine the identities of each of the qualifying aerosol particles by comparing the test spectra against predetermined spectra for known particle types. In this manner, activation cycling of a particle ablation laser of a single particle mass spectrometer is reduced.

  8. Observations of Sub-3 nm Particles and Sulfuric acid Concentrations during Aerosol Life Cycle Intensive Observation Period 2011 in Long Island, New York

    NASA Astrophysics Data System (ADS)

    Yu, H.; Kanawade, V. P.; You, Y.; Hallar, A. G.; Mccubbin, I. B.; Chirokova, G.; Sedlacek, A. J.; Springston, S. R.; Wang, J.; Kuang, C.; Lee, Y.; McGraw, R. L.; Mikkila, J.; Lee, S.

    2012-12-01

    Atmospheric new particle formation (NPF) is an important source of aerosol particles. But the NPF processes are not well understood, in part because of our limited understanding of the formation of atmospheric sub-3 nm size aerosols and the limited number of simultaneous observations of particle size distributions and the aerosol nucleation precursors. During Aerosol Life Cycle Intensive Observation Period (July-August 2011) in Long Island, New York, we deployed a particle size magnifier (Airmodus A09) running at different working fluid saturation ratios and a TSI CPC3776 to extract the information of sub-3 nm particles formation. A scanning mobility particle spectrometer (SMPS), a chemical ionization mass spectrometer (CIMS), and a number of atmospheric trace gas analyzers were used to simultaneously measure aerosol size distributions, sulfuric acid, and other possible aerosol precursors, respectively. Our observation results show that sub-3 nm particles existed during both NPF and non-NPF events, indicating the formation of sub-3nm particle didn't always lead to NPF characterized by typical banana shaped aerosol size distributions measured by SMPS. However, sub-3 nm particles were much higher during NPF events. Sub-3 nm particles were well-correlated with sulfuric acid showing the same diurnal variations and noontime peaks, especially for NPF days. These results are consistent with laboratory studies showing that formation of sub-3 nm particles is very sensitive to sulfuric acid (than amines and ammonia) [Yu et al. GRL 2012]. HYSPLIT back trajectory analysis indicates that air masses from Great Lakes, containing more SO2, VOCs and secondary organics, may contribute to growth of sub-3 nm particles and NPF.

  9. Aerosol chemistry in Titan's ionosphere: simultaneous growth and etching processes

    NASA Astrophysics Data System (ADS)

    Carrasco, Nathalie; Cernogora, Guy; Jomard, François; Etcheberry, Arnaud; Vigneron, Jackie

    2016-10-01

    Since the Cassini-CAPS measurements, organic aerosols are known to be present and formed at high altitudes in the diluted and partially ionized medium that is Titan's ionosphere [1]. This unexpected chemistry can be further investigated in the laboratory with plasma experiments simulating the complex ion-neutral chemistry starting from N2-CH4 [2]. Two sorts of solid organic samples can be produced in laboratory experiments simulating Titan's atmospheric reactivity: grains in the volume and thin films on the reactor walls. We expect that grains are more representative of Titan's atmospheric aerosols, but films are used to provide optical indices for radiative models of Titan's atmosphere.The aim of the present study is to address if these two sorts of analogues are chemically equivalent or not, when produced in the same N2-CH4 plasma discharge. The chemical compositions of both these materials are measured by using elemental analysis, XPS analysis and Secondary Ion Mass Spectrometry. We find that films are homogeneous but significantly less rich in nitrogen and hydrogen than grains produced in the same experimental conditions. This surprising difference in their chemical compositions is explained by the efficient etching occurring on the films, which stay in the discharge during the whole plasma duration, whereas the grains are ejected after a few minutes [3]. The impact for our understanding of Titan's aerosols chemical composition is important. Our study shows that chemical growth and etching process are simultaneously at stake in Titan's ionosphere. The more the aerosols stay in the ionosphere, the more graphitized they get through etching process. In order to infer Titan's aerosols composition, our work highlights a need for constraints on the residence time of aerosols in Titan's ionosphere. [1] Waite et al. (2009) Science , 316, p. 870[2] Szopa et al. (2006) PSS, 54, p. 394[3] Carrasco et al. (2016) PSS, 128, p. 52

  10. Mass-analysis of Charged Aerosol Particles in a PMSE/NLC Layer by a Rocket-borne Spectrometer

    NASA Astrophysics Data System (ADS)

    Robertson, Scott; Knappmiller, Scott; Horanyi, Mihaly; Sternovsky, Zoltan; Baumgarten, Gerd; Latteck, Ralph; Rapp, Markus; Holzworth, Robert; Shimogawa, Michael; Gumbel, Jorg; Megner, Ms Linda; Friedrich, Martin

    Two "MASS" rockets (Mesospheric Aerosol Sampling Spectrometer) were launched from the Andoya Rocket Range (Norway) the first week of August 2007. The payloads carried an electrostatic mass analyzer for the charged fraction of the aerosol particles, electric field booms, a photometer for cloud brightness, and Faraday rotation antennas for electron density. Aerosol particles with different ranges of charge-to-mass ratio were collected within the instrument housing on two sets of four biased collector plates, with one set for positive particles and one set for negative particles. The first rocket was launched into PMSE and NLC on 3 August. The sun was 4 degrees below the horizon and NLC were seen in the previous hour at 83 km by the ALOMAR RMR lidar. NLC were detected at the same altitude by rocket-borne photometer measurements. The charged aerosol data shows the density of negative particles with radius greater than 3 nm rising sharply at 83 km and continuing to 89 km, collocated with PMSE detected by the ALWIN radar. Particles with 1-2 nm radii with both signs of charge and particles with less than 1 nm radius charged positively were detected at 86-88 km. The occurrence of the positive particles in the smallest size range in the region of lowest temperature suggests that their origin is nucleation and growth on ions. Initial charge-density estimates are several thousands per cubic centimeter for each of these size ranges. The second launch was 6 August into PMSE without NLC. The 1-2 nm particles were seen from 85.4 to 87.4 km, again with both signs of charge. Larger sizes were nearly absent.

  11. Multiple new-particle growth pathways observed at the US DOE Southern Great Plains field site

    NASA Astrophysics Data System (ADS)

    Hodshire, Anna L.; Lawler, Michael J.; Zhao, Jun; Ortega, John; Jen, Coty; Yli-Juuti, Taina; Brewer, Jared F.; Kodros, Jack K.; Barsanti, Kelley C.; Hanson, Dave R.; McMurry, Peter H.; Smith, James N.; Pierce, Jeffery R.

    2016-07-01

    New-particle formation (NPF) is a significant source of aerosol particles into the atmosphere. However, these particles are initially too small to have climatic importance and must grow, primarily through net uptake of low-volatility species, from diameters ˜ 1 to 30-100 nm in order to potentially impact climate. There are currently uncertainties in the physical and chemical processes associated with the growth of these freshly formed particles that lead to uncertainties in aerosol-climate modeling. Four main pathways for new-particle growth have been identified: condensation of sulfuric-acid vapor (and associated bases when available), condensation of organic vapors, uptake of organic acids through acid-base chemistry in the particle phase, and accretion of organic molecules in the particle phase to create a lower-volatility compound that then contributes to the aerosol mass. The relative importance of each pathway is uncertain and is the focus of this work. The 2013 New Particle Formation Study (NPFS) measurement campaign took place at the DOE Southern Great Plains (SGP) facility in Lamont, Oklahoma, during spring 2013. Measured gas- and particle-phase compositions during these new-particle growth events suggest three distinct growth pathways: (1) growth by primarily organics, (2) growth by primarily sulfuric acid and ammonia, and (3) growth by primarily sulfuric acid and associated bases and organics. To supplement the measurements, we used the particle growth model MABNAG (Model for Acid-Base chemistry in NAnoparticle Growth) to gain further insight into the growth processes on these 3 days at SGP. MABNAG simulates growth from (1) sulfuric-acid condensation (and subsequent salt formation with ammonia or amines), (2) near-irreversible condensation from nonreactive extremely low-volatility organic compounds (ELVOCs), and (3) organic-acid condensation and subsequent salt formation with ammonia or amines. MABNAG is able to corroborate the observed differing growth

  12. Glass transition measurements in mixed organic and organic/inorganic aerosol particles

    NASA Astrophysics Data System (ADS)

    Dette, Hans Peter; Qi, Mian; Schröder, David; Godt, Adelheid; Koop, Thomas

    2014-05-01

    The recent proposal of a semi-solid or glassy state of secondary organic aerosol (SOA) particles has sparked intense research in that area. In particular, potential effects of a glassy aerosol state such as incomplete gas-to-particle partitioning of semi-volatile organics, inhibited chemical reactions and water uptake, and the potential to act as heterogeneous ice nuclei have been identified so far. Many of these studies use well-studied proxies for oxidized organics such as sugars or other polyols. There are, however, few measurements on compounds that do exist in atmospheric aerosol particles. Here, we have performed studies on the phase state of organics that actually occur in natural SOA particles arising from the oxidation of alpha-pinene emitted in boreal forests. We have investigated the two marker compounds pinonic acid and 3-methylbutane-1,2,3-tricarboxylic acid (3-MBTCA) and their mixtures. 3-MBCTA was synthesized from methyl isobutyrate and dimethyl maleate in two steps. In order to transfer these substances into a glassy state we have developed a novel aerosol spray drying technique. Dilute solutions of the relevant organics are atomized into aerosol particles which are dried subsequently by diffusion drying. The dried aerosol particles are then recollected in an impactor and studied by means of differential scanning calorimetry (DSC), which provides unambiguous information on the aerosols' phase state, i.e. whether the particles are crystalline or glassy. In the latter case DSC is used to determine the glass transition temperature Tg of the investigated samples. Using the above setup we were able to determine Tg of various mixtures of organic aerosol compounds as a function of their dry mass fraction, thus allowing to infer a relation between Tg and the O:C ratio of the aerosols. Moreover, we also studied the glass transition behavior of mixed organic/inorganic aerosol particles, including the effects of liquid-liquid phase separation upon drying.

  13. METHODS OF CALCULATINAG LUNG DELIVERY AND DEPOSITION OF AEROSOL PARTICLES

    EPA Science Inventory


    Lung deposition of aerosol is measured by a variety of methods. Total lung deposition can be measured by monitoring inhaled and exhaled aerosols in situ by laser photometry or by collecting the aerosols on filters. The measurements can be performed accurately for stable monod...

  14. Organic aggregate formation in aerosols and its impact on the physicochemical properties of atmospheric particles

    NASA Astrophysics Data System (ADS)

    Tabazadeh, Azadeh

    Fatty acid salts and "humic" materials, found in abundance in atmospheric particles, are both anionic surfactants. Such materials are known to form organic aggregates or colloids in solution at very low aqueous concentrations. In a marine aerosol, micelle aggregates can form at a low fatty acid salt molality of ˜10 -3 m. In other types of atmospheric particles, such as biomass burning, biogenic, soil dust, and urban aerosols, "humic-like" materials exist in sufficient quantities to form micelle-like aggregates in solution. I show micelle formation limits the ability of surface-active organics in aerosols to reduce the surface tension of an atmospheric particle beyond about 10 dyne cm -1. A general phase diagram is presented for anionic surfactants to explain how surface-active organics can change the water uptake properties of atmospheric aerosols. Briefly such molecules can enhance and reduce water uptake by atmospheric aerosols at dry and humid conditions, respectively. This finding is consistent with a number of unexplained field and laboratory observations. Dry electron microscope images of atmospheric particles often indicate that organics may coat the surface of particles in the atmosphere. The surfactant phase diagram is used to trace the particle path back to ambient conditions in order to determine whether such coatings can exist on wet ambient aerosols. Finally, I qualitatively highlight how organic aggregate formation in aerosols may change the optical properties and chemical reactivity of atmospheric particles.

  15. Enhanced high-temperature ice nucleation ability of crystallized aerosol particles after preactivation at low temperature

    NASA Astrophysics Data System (ADS)

    Wagner, Robert; Möhler, Ottmar; Saathoff, Harald; Schnaiter, Martin

    2014-07-01

    In cloud chamber experiments with crystallized aqueous ammonium sulfate, oxalic acid, and succinic acid solution droplets, we have studied a preactivation mechanism that markedly enhances the particles' heterogeneous ice nucleation ability. First cloud expansion experiments were performed at a high temperature (267-244 K) where the crystallized particles did not promote any heterogeneous ice nucleation. Ice nucleation at this temperature, however, could be triggered by temporarily cooling the crystallized particles to a lower temperature. This is because upon crystallization, residuals of the aqueous solution are trapped within the crystals. These captured liquids can freeze when cooled below their respective homogeneous or heterogeneous freezing temperature, leading to the formation of ice pockets in the crystalline particles. When warmed again to the higher temperature, ice formation by the preactivated particles occurred via depositional and deliquescence-induced ice growth, with ice active fractions ranging from 1 to 4% and from 4 to 20%, respectively. Preactivation disappeared above the eutectic temperature, which for the organic acids are close to the melting point of ice. This mechanism could therefore contribute to the very small fraction of atmospheric aerosol particles that are still ice active well above 263 K.

  16. Modelling non-equilibrium secondary organic aerosol formation and evaporation with the aerosol dynamics, gas- and particle-phase chemistry kinetic multi-layer model ADCHAM

    NASA Astrophysics Data System (ADS)

    Roldin, P.; Eriksson, A. C.; Nordin, E. Z.; Hermansson, E.; Mogensen, D.; Rusanen, A.; Boy, M.; Swietlicki, E.; Svenningsson, B.; Zelenyuk, A.; Pagels, J.

    2014-01-01

    We have developed the novel Aerosol Dynamics, gas- and particle-phase chemistry model for laboratory CHAMber studies (ADCHAM). The model combines the detailed gas phase Master Chemical Mechanism version 3.2, an aerosol dynamics and particle phase chemistry module (which considers acid catalysed oligomerization, heterogeneous oxidation reactions in the particle phase and non-ideal interactions between organic compounds, water and inorganic ions) and a kinetic multilayer module for diffusion limited transport of compounds between the gas phase, particle surface and particle bulk phase. In this article we describe and use ADCHAM to study: (1) the mass transfer limited uptake of ammonia (NH3) and formation of organic salts between ammonium (NH4+) and carboxylic acids (RCOOH), (2) the slow and almost particle size independent evaporation of α-pinene secondary organic aerosol (SOA) particles, and (3) the influence of chamber wall effects on the observed SOA formation in smog chambers. ADCHAM is able to capture the observed α-pinene SOA mass increase in the presence of NH3(g). Organic salts of ammonium and carboxylic acids predominantly form during the early stage of SOA formation. These salts contribute substantially to the initial growth of the homogeneously nucleated particles. The model simulations of evaporating α-pinene SOA particles support the recent experimental findings that these particles have a semi-solid tar like amorphous phase state. ADCHAM is able to reproduce the main features of the observed slow evaporation rates if low-volatility and viscous oligomerized SOA material accumulates in the particle surface layer upon evaporation. The evaporation rate is mainly governed by the reversible decomposition of oligomers back to monomers. Finally, we demonstrate that the mass transfer limited uptake of condensable organic compounds onto wall deposited particles or directly onto the Teflon chamber walls of smog chambers can have profound influence on the

  17. Insights into the growth of newly formed particles in a subtropical urban environment

    NASA Astrophysics Data System (ADS)

    Salimi, F.; Crilley, L. R.; Stevanovic, S.; Ristovski, Z.; Mazaheri, M.; He, C.; Johnson, G.; Ayoko, G.; Morawska, L.

    2015-12-01

    The role of different chemical compounds, particularly organics, involved in the new particle formation (NPF) and its consequent growth are not fully understood. Therefore, this study was conducted to investigate the chemical composition of aerosol particles during NPF events in an urban subtropical environment. Aerosol chemical composition was measured along with particle number size distribution (PNSD) and several other air quality parameters at five sites across an urban subtropical environment. An Aerodyne compact Time-of-Flight Aerosol Mass Spectrometer (c-ToF-AMS) and a TSI Scanning Mobility Particle Sizer (SMPS) measured aerosol chemical composition (particles above 50 nm in vacuum aerodynamic diameter) and PNSD (particles within 9-414 nm in mobility diameter), respectively. Five NPF events, with growth rates in the range 3.3-4.6 nm, were detected at two of the sites. The NPF events happened on relatively warmer days with lower condensation sink (CS). Temporal percent fractions of organics increased after the particles grew enough to have a significant contribution to particle volume, while the mass fraction of ammonium and sulfate decreased. This uncovered the important role of organics in the growth of newly formed particles. Three organic markers, factors f43, f44 and f57, were calculated and the f44 vs. f43 trends were compared between nucleation and non-nucleation days. K-means cluster analysis was performed on f44 vs. f43 data and it was found that they follow different patterns on nucleation days compared to non-nucleation days, whereby f43 decreased for vehicle-emission-generated particles, while both f44 and f43 decreased for NPF-generated particles. It was found for the first time that vehicle-generated and newly formed particles cluster in different locations on f44 vs. f43 plot, and this finding can be potentially used as a tool for source apportionment of measured particles.

  18. Inorganic aerosol formation and growth in the Earth's lower and upper atmosphere

    NASA Astrophysics Data System (ADS)

    Saunders, R. W.; Plane, J. M. C.

    2006-12-01

    This chapter describes the photo-chemical production of aerosol particles in two very different regions of the atmosphere: iodine oxide particles in the marine boundary layer (MBL), and meteoric smoke particles that form in the upper mesosphere from the ablation of interplanetary dust. These two systems are surprisingly analogous the source of the condensable inorganic vapours is external to the atmosphere, being injected into the atmosphere from the ocean or from space and the particles are formed by homogeneous nucleation. The purpose of the chapter is to describe a laboratory and modelling study to understand at a fundamental level how the nucleation and growth of the particles occurs. Iodine oxide particles were produced from the photo-oxidation of gaseous I{2} with O{3}, which is most likely the primary photo-chemical route to produce the bursts of new particles observed in the MBL at seaweed-rich coastal locations. The captured particles were observed to be fractal-like (i.e., with open or non-compact structures), and to be composed of the stable oxide I{2}O{5}. Meteoric smoke analogues of iron oxide, silicon oxide, and iron silicate composition were similarly formed from the photo-oxidation of iron- and silicon-containing gas-phase precursors in the presence of O{3}. Imaging of the iron-containing particles showed them to be extended, fractal aggregates. For each system, models were developed to elucidate the growth kinetics of the particles and to characterise them in terms of standard fractal parameters. I{2}O{5} particles were found to have a fractal dimension (Df) value of 2.5 at long growth times, consistent with a particle-cluster diffusion-limited aggregation (DLA) mechanism, whereas smoke analogues had lower Df values (1.75) which appear to result from a magnetic aggregation process.

  19. Modeling aerosol growth by aqueous chemistry in nonprecipitating stratiform cloud

    SciTech Connect

    Ovchinnikov, Mikhail; Easter, Richard C.

    2010-07-29

    A new microphysics module based on a two-dimensional (2D) joint size distribution function representing both interstitial and cloud particles is developed and applied to studying aerosol processing in non-precipitating stratocumulus clouds. The module is implemented in a three-dimensional dynamical framework of a large-eddy simulation (LES) model and in a trajectory ensemble model (TEM). Both models are used to study the modification of sulfate aerosol by the activation - aqueous chemistry - resuspension cycle in shallow marine stratocumulus clouds. The effect of particle mixing and different size-distribution representations on modeled aerosol processing are studied in a comparison of the LES and TEM simulations with the identical microphysics treatment exposes and a comparison of TEM simulations with a 2D fixed and moving bin microphysics. Particle mixing which is represented in LES and neglected in the TEM leads to the mean relative per particle dry mass change in the TEM simulations being about 30% lower than in analogous subsample of LES domain. Particles in the final LES spectrum are mixed in from different “parcels”, some of which have experienced longer in-cloud residence times than the TEM parcels, all of which originated in the subcloud layer, have. The mean relative per particle dry mass change differs by 14% between TEM simulations with fixed and moving bin microphysics. Finally, the TEM model with the moving bin microphysics is used to evaluate assumptions about liquid water mass partitioning among activated cloud condensation nuclei (CCN) of different dry sizes. These assumptions are used in large-scale models to map the bulk aqueous chemistry sulfate production, which is largely proportional to the liquid water mass, to the changes in aerosol size distribution. It is shown that the commonly used assumptions that the droplet mass is independent of CCN size or that the droplet mass is proportional to the CCN size to the third power do not perform

  20. Resuspension of Aerosol Particles from Evaporated Rain Drops to the Coarse Mode

    NASA Astrophysics Data System (ADS)

    Wang, H.; Easter, R. C.; Ganguly, D.; Singh, B.; Rasch, P. J.

    2015-12-01

    Precipitation scavenging (i.e., wet removal) has long been recognized as one of the major removal processes for tropospheric aerosol particles, and the dominant one for accumulation-mode size particles. When rain drops evaporate, the aerosol material contained in drops is resuspended, and this process has received much less attention. Unlike the resuspension from evaporated cloud droplets, the aerosol particles resuspended from evaporated rain drops have much larger sizes than most of the aerosol particles that acted as cloud condensation nuclei (CCN), became cloud borne, and then were collected by rain drops, because each rain drop generally collects thousands of cloud droplets. Here we present some aspects of this resuspension process obtained from modeling studies. First, we investigate some details of the process using a simple drop-size resolved model of raindrop evaporation in sub-saturated air below cloud base. Using these results, we then investigate different treatments of this process in a global aerosol and climate model that employs a modal aerosol representation. Compared to the model's original treatment of this process in which rain-borne aerosol is resuspended to the mode that it came from with its original size, the new treatment that resuspends to the coarse mode produces notable reductions in global CCN concentrations, as well as sulfate, black carbon, and organic aerosol mass, because the resuspended aerosol particles have much shorter lifetimes due to their larger sizes. Somewhat surprisingly, there are also notable reductions in coarse-mode sea salt and mineral dust burdens. These species are resuspended to the coarse mode in both the original and new treatments, but these resuspended particles are fewer in number and larger in size in the new treatment. This finding highlights some issues of the modal aerosol treatment for coarse mode particles.

  1. Hygroscopic properties of aerosol particles at high relative humidity and their diurnal variations in the North China Plain

    NASA Astrophysics Data System (ADS)

    Liu, P. F.; Zhao, C. S.; Göbel, T.; Hallbauer, E.; Nowak, A.; Ran, L.; Xu, W. Y.; Deng, Z. Z.; Ma, N.; Mildenberger, K.; Henning, S.; Stratmann, F.; Wiedensohler, A.

    2011-01-01

    The hygroscopic properties of submicron aerosol particles were determined at a suburban site (Wuqing) in the North China Plain among a cluster of cities during the period 17 July to 12 August 2009. A High Humidity Tandem Differential Mobility Analyser (HH-TDMA) instrument was applied to measure the hygroscopic growth factor (GF) at 90%, 95% and 98.5% relative humidity (RH) for particles with dry diameter between 50-250 nm. The probability distribution of GF (GF-PDF) averaged over the period shows a distinct bimodal pattern, namely, a dominant more-hygroscopic (MH) group and a smaller nearly-hydrophobic (NH) group. The MH group particles were highly hygroscopic, and their GF was relatively constant during the period with average values of 1.54±0.02, 1.81±0.04 and 2.45±0.07 at 90%, 95% and 98.5% RH (D0=100 nm), respectively. The NH group particles grew very slightly when exposed to high RH, with GF values of 1.08±0.02, 1.13±0.06 and 1.24±0.13, respectively at 90%, 95% and 98.5% RH (D0=100 nm). The hygroscopic growth behaviours at different RHs were well represented by the hygroscopicity parameter κ with a single-parameter Köhler model. Thus, the calculation of GF as a function of RH and dry diameter could be facilitated by an empirical parameterization of κ as function of dry diameter. A strong diurnal pattern in number fraction of different hygroscopic groups was observed, indicating a diurnal variation of aerosol mixing state and/or chemical composition. The average number fraction of NH particles during the day was about 8%, while during the nighttime fractions up to 20% were reached. Correspondingly, the state of mixing in terms of water uptake varied significantly during a day. The high fraction of NH particles measured during the night denotes a high degree of external mixing of ambient aerosols, while during the day the degree of external mixing decreased. Simulations using a particle-resolved aerosol box model (PartMC-MOSAIC) suggest that the diurnal

  2. Final Report: "Collaborative Project. Understanding the Chemical Processes That Affect Growth Rates of Freshly Nucleated Particles"

    SciTech Connect

    Smith, James N.; McMurry, Peter H.

    2015-11-12

    This final technical report describes our research activities that have, as the ultimate goal, the development of a model that explains growth rates of freshly nucleated particles. The research activities, which combine field observations with laboratory experiments, explore the relationship between concentrations of gas-phase species that contribute to growth and the rates at which those species are taken up. We also describe measurements of the chemical composition of freshly nucleated particles in a variety of locales, as well as properties (especially hygroscopicity) that influence their effects on climate. Our measurements include a self-organized, DOE-ARM funded project at the Southern Great Plains site, the New Particle Formation Study (NPFS), which took place during spring 2013. NPFS data are available to the research community on the ARM data archive, providing a unique suite observations of trace gas and aerosols that are associated with the formation and growth of atmospheric aerosol particles.

  3. Effects of amines on particle growth observed in new particle formation events

    NASA Astrophysics Data System (ADS)

    Tao, Ye; Ye, Xingnan; Jiang, Shuqing; Yang, Xin; Chen, Jianmin; Xie, Yuanyuan; Wang, Ruyu

    2016-01-01

    Particle size distributions in the range of 0.01-10 µm were measured in urban Shanghai in the summer of 2013 using a Wide-range Particle Spectrometer (WPS). Size-segregated aerosol samples were collected concurrently using a Micro-Orifice Uniform Deposit Impactor (MOUDI), which aided our in-depth understanding of the new particle formation (NPF) mechanism in the polluted Yangtze River Delta area. During the observations, 16 NPF events occurred at high temperatures (~34.7°C) on clear and sunny days. In the ammonium-poor PM1.0 (particulate matter less than 1.0 µm), sulfate and ammonium accounted for 92% of the total water-soluble inorganic species. Six aminiums were detected in these MOUDI samples, among which the group of diethylaminium and trimethylaminium (DEAH+ + TMAH+) was the most abundant. The very high level of aminiums (average concentration up to 86.4 ng m-3 in PM1.8), together with highly acidic aerosols, provided insight into the frequent NPF events. The high mass ratio of total aminiums to NH4+ (>0.2 for PM0.056) further highlighted the important role of amines in promoting NPF. The concentration of DEAH+ + TMAH+ in new particles below 180 nm was strongly correlated with aerosol phase acidity, indicating that acid-base reactions dominated the aminium formation in NPF events. The unexpected enhancement of DEAH+ + TMAH+ on a nonevent day was attributed to the transportation of an SO2 plume. Our results reveal that the heterogeneous uptake of amines is dominated by the acid-base reaction mechanism, which can effectively contribute to particle growth in NPF events.

  4. The impact of aerosol hygroscopic growth on the single-scattering albedo and its application on the NO2 photolysis rate coefficient

    NASA Astrophysics Data System (ADS)

    Tao, Jiangchuan; Zhao, Chunsheng

    2016-04-01

    Hygroscopic growth of aerosol particles can significantly affect their single-scattering albedo (ω), and consequently alters the aerosol effect on tropospheric photochemistry. In this study, the impact of aerosol hygroscopic growth on ω and its application to the NO2 photolysis rate coefficient (JNO2) are investigated for a typical aerosol particle population in the North China Plain (NCP). The variations of aerosol optical properties with relative humidity (RH) are calculated using a Mie theory aerosol optical model, on the basis of field measurements of number-size distribution and hygroscopic growth factor (at RH values above 90 %) from the 2009 HaChi (Haze in China) project. Results demonstrate that ambient ω has pronouncedly different diurnal patterns from ω measured at dry state, and is highly sensitive to the ambient RHs. Ambient ω in the NCP can be described by a dry state ω value of 0.863, increasing with the RH following a characteristic RH dependence curve. A Monte Carlo simulation shows that the uncertainty ofω from the propagation of uncertainties in the input parameters decreases from 0.03 (at dry state) to 0.015 (RHs > 90 %). The impact of hygroscopic growth on ω is further applied in the calculation of the radiative transfer process. Hygroscopic growth of the studied aerosol particle population generally inhibits the photolysis of NO2 at the ground level, whereas accelerates it above the moist planetary boundary layer. Compared with dry state, the calculated JNO2 at RH of 98 % at the height of 1 km increases by 30.4 %, because of the enhancement of ultraviolet radiation by the humidified scattering-dominant aerosol particles. The increase of JNO2 due to the aerosol hygroscopic growth above the upper boundary layer may affect the tropospheric photochemical processes and this needs to be taken into account in the atmospheric chemical models.

  5. Electron mean free path from angle-dependent photoelectron spectroscopy of aerosol particles

    SciTech Connect

    Goldmann, Maximilian; Miguel-Sánchez, Javier; West, Adam H. C.; Yoder, Bruce L.; Signorell, Ruth

    2015-06-14

    We propose angle-resolved photoelectron spectroscopy of aerosol particles as an alternative way to determine the electron mean free path of low energy electrons in solid and liquid materials. The mean free path is obtained from fits of simulated photoemission images to experimental ones over a broad range of different aerosol particle sizes. The principal advantage of the aerosol approach is twofold. First, aerosol photoemission studies can be performed for many different materials, including liquids. Second, the size-dependent anisotropy of the photoelectrons can be exploited in addition to size-dependent changes in their kinetic energy. These finite size effects depend in different ways on the mean free path and thus provide more information on the mean free path than corresponding liquid jet, thin film, or bulk data. The present contribution is a proof of principle employing a simple model for the photoemission of electrons and preliminary experimental data for potassium chloride aerosol particles.

  6. Apparatus having reduced background for measuring radiation activity in aerosol particles

    DOEpatents

    Rodgers, John C.; McFarland, Andrew R.; Oritz, Carlos A.; Marlow, William H.

    1992-01-01

    Apparatus having reduced background for measuring radiation activity in aerosol particles. A continuous air monitoring sampler is described for use in detecting the presence of alpha-emitting aerosol particles. An inlet fractionating screen has been demonstrated to remove about 95% of freshly formed radon progeny from the aerosol sample, and approximately 33% of partially aged progeny. Addition of an electrical condenser and a modified dichotomous virtual impactor are expected to produce considerable improvement in these numbers, the goal being to enrich the transuranic (TRU) fraction of the aerosols. This offers the possibility of improving the signal-to-noise ratio for the detected alpha-particle energy spectrum in the region of interest for detecting TRU materials associated with aerosols, thereby enhancing the performance of background-compensation algorithms for improving the quality of alarm signals intended to warn personnel of potentially harmful quantities of TRU materials in the ambient air.

  7. New Particle Formation and Growth in CMAQ: Application of Comprehensive Modal Methods to Observations during CalNex 2010

    NASA Astrophysics Data System (ADS)

    Murphy, B.

    2015-12-01

    Secondary formation and subsequent growth of ultrafine atmospheric particles is an important source of larger particles that can activate clouds and affect their microphysical properties. It is likewise important for models attempting to quantify cloud-aerosol feedbacks to realistically account for this pervasive pathway. Representing these phenomena accurately in models requires in-depth knowledge of the chemical interactions that lead to new particle formation as well as the availability of condensable species to sustain a growth event. Further, models must represent the numerical aspects of particle growth reasonably well in order to preserve the essential characteristics of the aerosol size distribution (e.g. unimodal vs. bimodal, peak diameter, etc). Such characteristics are critical for calculating the number of particles participating as nuclei for liquid and solid hydrometeors. We implement into the Community Multi-scale Air Quality (CMAQ) model a new aerosol processing module designed for robust prediction of particle number concentrations, sources and sinks. The new module leverages the speed and flexibility of modal aerosol techniques with state-of-the-art, schemes for treating new particle formation, coagulation, and intermodal transference. Moreover, we incorporate an updated treatment of organic aerosol (OA) formation and explore the sensitivity of growth rates predicted by the CMAQ model to the uncertain OA formation parameters. We apply the new model to observations made during the CalNex 2010 campaign and evaluate model performance against observed number concentrations, time-dependent growth rates, and size distributions.

  8. Spectro-microscopy of Ambient Aerosol Particles: Observational Constraints on Mixing State Parameterization

    NASA Astrophysics Data System (ADS)

    OBrien, R. E.; Wang, B.; Laskin, A.; West, M.; Riemer, N. S.; Gilles, M. K.; Moffet, R.

    2014-12-01

    Individual aerosol particles are often mixtures of multiple components such as inorganic salts, soot or elemental carbon, and organic molecules. The amounts of the different components in each particle and the particle morphologies will impact the CCN activity and the radiative properties of the aerosol population. A recent parameterization of the mixing state developed by Nicole Riemer and Matthew West provides a clear transition between ambient measurements of aerosol components and particle mixing states employed in climate models. Single particle spectro-microscopy techniques including scanning transmission x-ray microscopy/near-edge x-ray absorption fine structure spectroscopy (STXM/NEXAFS) and computer controlled scanning electron microscopy/energy dispersive x-ray spectroscopy (CCSEM/EDX) are used to measure the composition of aerosol particles from the CARES campaign at both T0 and T1. Here, we present results from the application of the per particle composition to a parameterization of the mixing state and provide constraints on the mixing state of ambient aerosol particles. The two microscopy techniques yield complementary information on the mixing state of the aerosol populations; STXM/NEXAFS provides information on the mixing state of the organic fraction while CCSEM/EDX provides information on the inorganic fraction.

  9. Experimental Assessment of Collection Efficiency of Submicron Aerosol Particles by Cloud Droplets

    NASA Astrophysics Data System (ADS)

    Huang, Y.; Oo, K.; Brown, M. D.; Dhaniyala, S.; Cziczo, D. J.

    2012-12-01

    An experimental setup has been constructed to measure the collection efficiency of submicron aerosol particles by cloud droplets. The collection efficiency study is a prelude to studying contact nucleation, which is a potentially important ice nucleation mode that is not well-understood. This laboratory setup is a step closer to experimentally assessing the importance of contact nucleation. Water droplets with 20 micron diameter and submicron aerosol particles are brought into contact in an injector situated inside a chilled glass flow tube. The water droplets that collect aerosol particles are allowed to pass through a counterflow virtual impactor (CVI), which accepts large droplets and rejects aerosol particles that have not coagulated with the water droplets. The collected droplets are sent into the Particle Analysis by Laser Mass Spectrometry (PALMS) instrument which performs in situ chemical analysis of a single particle. The number of aerosol particles collected by the single water droplet is quantified by calibrating the PALMS with known concentrations of aerosol particles. The water droplets contain a known amount of ammonium sulfate for identification purpose in the mass spectrometry. Preliminary results from the experiment will be discussed and compared with previous theoretical and experimental studies.

  10. Optical and Physicochemical Properties of Brown Carbon Aerosol: Light Scattering, FTIR Extinction Spectroscopy, and Hygroscopic Growth.

    PubMed

    Tang, Mingjin; Alexander, Jennifer M; Kwon, Deokhyeon; Estillore, Armando D; Laskina, Olga; Young, Mark A; Kleiber, Paul D; Grassian, Vicki H

    2016-06-23

    in the mid-IR range (800 to 7000 cm(-1)) also showed no significant changes in either the real or the imaginary parts of the refractive indices for brown carbon aerosol particles when compared to ammonium sulfate. Therefore, changes in the optical properties of ammonium sulfate in the mid-IR spectral range due to reaction with methylglyoxal appear to be insignificant. In addition to these measurements, we have characterized additional physicochemical properties of the brown carbon aerosol particles including hygroscopic growth using a tandem-differential mobility analyzer. Compared to ammonium sulfate, brown carbon aerosol particles are found to have lower deliquescence relative humidity (DRH), efflorescence relative humidity (ERH), and hygroscopic growth at the same relative humidities. Overall, our study provides new details of the optical and physicochemical properties of a class of secondary organic aerosol which may have important implications for atmospheric chemistry and climate.

  11. Optical and Physicochemical Properties of Brown Carbon Aerosol: Light Scattering, FTIR Extinction Spectroscopy, and Hygroscopic Growth.

    PubMed

    Tang, Mingjin; Alexander, Jennifer M; Kwon, Deokhyeon; Estillore, Armando D; Laskina, Olga; Young, Mark A; Kleiber, Paul D; Grassian, Vicki H

    2016-06-23

    in the mid-IR range (800 to 7000 cm(-1)) also showed no significant changes in either the real or the imaginary parts of the refractive indices for brown carbon aerosol particles when compared to ammonium sulfate. Therefore, changes in the optical properties of ammonium sulfate in the mid-IR spectral range due to reaction with methylglyoxal appear to be insignificant. In addition to these measurements, we have characterized additional physicochemical properties of the brown carbon aerosol particles including hygroscopic growth using a tandem-differential mobility analyzer. Compared to ammonium sulfate, brown carbon aerosol particles are found to have lower deliquescence relative humidity (DRH), efflorescence relative humidity (ERH), and hygroscopic growth at the same relative humidities. Overall, our study provides new details of the optical and physicochemical properties of a class of secondary organic aerosol which may have important implications for atmospheric chemistry and climate. PMID:27253434

  12. Direct measurements of the optical cross sections and refractive indices of individual volatile and hygroscopic aerosol particles.

    PubMed

    Mason, B J; Cotterell, M I; Preston, T C; Orr-Ewing, A J; Reid, J P

    2015-06-01

    We present measurements of the evolving extinction cross sections of individual aerosol particles (spanning 700-2500 nm in radius) during the evaporation of volatile components or hygroscopic growth using a combination of a single particle trap formed from a Bessel light beam and cavity ring-down spectroscopy. For single component organic aerosol droplets of 1,2,6-hexanetriol, polyethylene glycol 400, and glycerol, the slow evaporation of the organic component (over time scales of 1000 to 10,000 s) leads to a time-varying size and extinction cross section that can be used to estimate the refractive index of the droplet. Measurements on binary aqueous-inorganic aerosol droplets containing one of the inorganic solutes ammonium bisulfate, ammonium sulfate, sodium nitrate, or sodium chloride (over time scales of 1000 to 15,000 s) under conditions of changing relative humidity show that extinction cross-section measurements are consistent with expectations from accepted models for the variation in droplet refractive index with hygroscopic growth. In addition, we use these systems to establish an experimental protocol for future single particle extinction measurements. The advantages of mapping out the evolving light extinction cross-section of an individual particle over extended time frames accompanied by hygroscopic cycling or component evaporation are discussed.

  13. Identification of characteristic mass spectrometric markers for primary biological aerosol particles and comparison with field data from submicron pristine aerosol particles

    NASA Astrophysics Data System (ADS)

    Freutel, F.; Schneider, J.; Zorn, S. R.; Drewnick, F.; Borrmann, S.; Hoffmann, T.; Martin, S. T.

    2009-04-01

    The contribution of primary biological aerosol (PBA) to the total aerosol particle concentration is estimated to range between 25 and 80%, depending on location and season. Especially in the tropical rain forest it is expected that PBA is a major source of particles in the supermicron range, and is also an important fraction of the submicron aerosol. PBA particles like plant fragments, pollen, spores, fungi, viruses etc. contain chemical compounds as proteins, sugars, amino acids, chlorophyll, and cellular material as cellulose. For this reason we have performed mass spectrometric laboratory measurements (Aerodyne C-ToF and W-ToF AMS, single particle laser ablation instrument SPLAT) on pure submicron aerosol particles containing typical PBA compounds in order to identify typical mass spectral patterns of these compounds and to explain the observed fragmentation patterns on the basis of molecular structures. These laboratory data were compared to submicron particle mass spectra obtained during AMAZE-08 (Amazonian Aerosol CharacteriZation Experiment, Brazil, February/March 2008). The results indicate that characteristic m/z ratios for carbohydrates (e.g., glucose, saccharose, levoglucosan, mannitol) can be identified, for example m/z = 60(C2H4O2+) or m/z = 61(C2H5O2+). Certain characteristic peaks for amino acids were also identified in the laboratory experiments. In the field data from AMAZE-08, these characteristic peaks for carbohydrates and amino acids were found, and their contribution to the total organic mass was estimated to about 5%. Fragment ions from peptides and small proteins were also identified in laboratory experiments. Larger proteins, however, seem to become oxidized to CO2+ to a large extend in the vaporizing process of the AMS. Thus, detection of proteins in atmospheric aerosol particles with the AMS appears to be difficult.

  14. Reduction in biomass burning aerosol light absorption upon humidification: Roles of inorganically-induced hygroscopicity, particle collapse, and photoacoustic heat and mass transfer

    SciTech Connect

    lewis, Kristen A.; Arnott, W. P.; Moosmuller, H.; Chakrabarti, Raj; Carrico, Christian M.; Kreidenweis, Sonia M.; Day, Derek E.; Malm, William C.; Laskin, Alexander; Jimenez, Jose L.; Ulbrich, Ingrid M.; Huffman, John A.; Onasch, Timothy B.; Trimborn, Achim; Liu, Li; Mishchenko, M.

    2009-11-27

    Smoke particle emissions from the combustion of biomass fuels typical for the western and southeastern United States were studied and compared under high humidity and ambient conditions in the laboratory. The fuels used are Montana ponderosa pine (Pinus ponderosa), southern California chamise (Adenostoma fasciculatum), and Florida saw palmetto (Serenoa repens). Information on the non-refractory chemical composition of biomass burning aerosol from each fuel was obtained with an aerosol mass spectrometer and through estimation of the black carbon concentration from light absorption measurements at 870 nm. Changes in the optical and physical particle properties under high humidity conditions were observed for hygroscopic smoke particles containing substantial inorganic mass fractions that were emitted from combustion of chamise and palmetto fuels. Light scattering cross sections increased under high humidity for these particles, consistent with the hygroscopic growth measured for 100 nm particles in HTDMA measurements. Photoacoustic measurements of aerosol light absorption coefficients reveal a 20% reduction with increasing relative humidity, contrary to the expectation of light absorption enhancement by the liquid coating taken up by hygroscopic particles. This reduction is hypothesized to arise from two mechanisms: 1. Shielding of inner monomers after particle consolidation or collapse with water uptake; 2. The contribution of mass transfer through evaporation and condensation at high relative humidity to the usual heat transfer pathway for energy release by laser heated particles in the photoacoustic measurement of aerosol light absorption. The mass transfer contribution is used to evaluate the fraction of aerosol surface covered with liquid water solution as a function of RH.

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

    NASA Astrophysics Data System (ADS)

    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

  16. Investigating the Internal Structure of Individual Aerosol Particles Using Atomic Force and Raman Microscopies

    NASA Astrophysics Data System (ADS)

    Freedman, M. A.; Baustian, K. J.; Wise, M. E.; Tolbert, M. A.

    2009-12-01

    We have used Atomic Force Microscopy (AFM) and Raman Microscopy to probe aerosol internal structures in order to understand the optical properties of aerosols composed of mixtures of organic and inorganic components. While AFM gives only topographical information about the particles, indirect chemical information can be obtained by using substrates with different surface properties. With Raman microscopy, chemical signatures of the components of the aerosol are obtained, but we have limited spatial resolution. We have explored the use of these two techniques to look at aerosol internal structure using a range of different model aerosols composed of mixtures of ammonium sulfate with organic compounds of various solubilities such as sucrose, succinic acid, and palmitic acid. At the extremes of solubility, AFM provides suitable information for interpreting aerosol microstructure. For example, AFM clearly shows the presence of core-shell structures for aerosol particles composed of palmitic acid and ammonium sulfate, while the results for aerosol particles composed of succinic acid and ammonium sulfate are more difficult to interpret. Information about size and shape can be obtained when hydrophilic particles are impacted on hydrophobic substrates and vise versa. With Raman microscopy, core-shell structures were readily identified for ammonium sulfate with palmitic acid or succinic acid coatings. For the case of succinic acid and ammonium sulfate mixtures, we are using microscopy results to aid in interpreting the refractive indices we retrieved from cavity ring-down studies.

  17. Evaluation of cell sorting aerosols and containment by an optical airborne particle counter.

    PubMed

    Xie, Mike; Waring, Michael T

    2015-08-01

    Understanding aerosols produced by cell sorting is critical to biosafety risk assessment and validation of containment efficiency. In this study an Optical Airborne Particle Counter was used to analyze aerosols produced by the BD FACSAria and to assess the effectiveness of its aerosol containment. The suitability of using this device to validate containment was directly compared to the Glo-Germ method put forth by the International Society for Advancement of Cytometry (ISAC) as a standard for testing. It was found that high concentrations of aerosols ranging from 0.3 µm to 10 µm can be detected in failure mode, with most less than 5 µm. In most cases, while numerous aerosols smaller than 5 µm were detected by the Optical Airborne Particle Counter, no Glo-Germ particles were detected, indicating that small aerosols are under-evaluated by the Glo-Germ method. The results demonstrate that the Optical Airborne Particle Counter offers a rapid, economic, and quantitative analysis of cell sorter aerosols and represents an improved method over Glo-Germ for the task of routine validation and monitoring of aerosol containment for cell sorting. PMID:26012776

  18. A Micro Aerosol Sensor for the Measurement of Airborne Ultrafine Particles.

    PubMed

    Zhang, Chao; Zhu, Rong; Yang, Wenming

    2016-01-01

    Particle number concentration and particle size are the two key parameters used to characterize exposure to airborne nanoparticles or ultrafine particles that have attracted the most attention. This paper proposes a simple micro aerosol sensor for detecting the number concentration and particle size of ultrafine particles with diameters from 50 to 253 nm based on electrical diffusion charging. The sensor is composed of a micro channel and a couple of planar electrodes printed on two circuit boards assembled in parallel, which thus integrate charging, precipitating and measurement elements into one chip, the overall size of which is 98 × 38 × 25 mm³. The experiment results demonstrate that the sensor is useful for measuring monodisperse aerosol particles with number concentrations from 300 to 2.5 × 10⁴ /cm³ and particle sizes from 50 to 253 nm. The aerosol sensor has a simple structure and small size, which is favorable for use in handheld devices. PMID:26999156

  19. A Micro Aerosol Sensor for the Measurement of Airborne Ultrafine Particles

    PubMed Central

    Zhang, Chao; Zhu, Rong; Yang, Wenming

    2016-01-01

    Particle number concentration and particle size are the two key parameters used to characterize exposure to airborne nanoparticles or ultrafine particles that have attracted the most attention. This paper proposes a simple micro aerosol sensor for detecting the number concentration and particle size of ultrafine particles with diameters from 50 to 253 nm based on electrical diffusion charging. The sensor is composed of a micro channel and a couple of planar electrodes printed on two circuit boards assembled in parallel, which thus integrate charging, precipitating and measurement elements into one chip, the overall size of which is 98 × 38 × 25 mm3. The experiment results demonstrate that the sensor is useful for measuring monodisperse aerosol particles with number concentrations from 300 to 2.5 × 104 /cm3 and particle sizes from 50 to 253 nm. The aerosol sensor has a simple structure and small size, which is favorable for use in handheld devices. PMID:26999156

  20. [Factors influencing particle measurement of aerosols and their retention in the lung].

    PubMed

    Le Bouffant, L

    1977-01-01

    The dimensional characteristics of the particles of an aerosol depend on the means used for producing them. Mechanical spray and ultrasonic dispersion give polydispersed particles. On the other hand, centrifugal atomization produces a monodispersed aerosol. Particle retention in the lung system depends on the particle diameter. In addition, retention varies according to the respiratory characteristics: it is minimal for about 15 inspirations per minute. Using iron-59 labeled particles, it was shown that the degree of retention varies considerably from one individual to the other and accessibility to the depths of the lungs is decreased under the effect of certain lesions. Bronchial retention appears to be increased in smokers.

  1. Estimating Marine Aerosol Particle Volume and Number from Maritime Aerosol Network Data

    NASA Technical Reports Server (NTRS)

    Sayer, A. M.; Smirnov, A.; Hsu, N. C.; Munchak, L. A.; Holben, B. N.

    2012-01-01

    As well as spectral aerosol optical depth (AOD), aerosol composition and concentration (number, volume, or mass) are of interest for a variety of applications. However, remote sensing of these quantities is more difficult than for AOD, as it is more sensitive to assumptions relating to aerosol composition. This study uses spectral AOD measured on Maritime Aerosol Network (MAN) cruises, with the additional constraint of a microphysical model for unpolluted maritime aerosol based on analysis of Aerosol Robotic Network (AERONET) inversions, to estimate these quantities over open ocean. When the MAN data are subset to those likely to be comprised of maritime aerosol, number and volume concentrations obtained are physically reasonable. Attempts to estimate surface concentration from columnar abundance, however, are shown to be limited by uncertainties in vertical distribution. Columnar AOD at 550 nm and aerosol number for unpolluted maritime cases are also compared with Moderate Resolution Imaging Spectroradiometer (MODIS) data, for both the present Collection 5.1 and forthcoming Collection 6. MODIS provides a best-fitting retrieval solution, as well as the average for several different solutions, with different aerosol microphysical models. The average solution MODIS dataset agrees more closely with MAN than the best solution dataset. Terra tends to retrieve lower aerosol number than MAN, and Aqua higher, linked with differences in the aerosol models commonly chosen. Collection 6 AOD is likely to agree more closely with MAN over open ocean than Collection 5.1. In situations where spectral AOD is measured accurately, and aerosol microphysical properties are reasonably well-constrained, estimates of aerosol number and volume using MAN or similar data would provide for a greater variety of potential comparisons with aerosol properties derived from satellite or chemistry transport model data.

  2. Ambient measurement of fluorescent aerosol particles with a WIBS in the Yangtze River Delta of China: potential impacts of combustion-related aerosol particles

    NASA Astrophysics Data System (ADS)

    Yu, Xiawei; Wang, Zhibin; Zhang, Minghui; Kuhn, Uwe; Xie, Zhouqing; Cheng, Yafang; Pöschl, Ulrich; Su, Hang

    2016-09-01

    Fluorescence characteristics of aerosol particles in a polluted atmosphere were studied using a wideband integrated bioaerosol spectrometer (WIBS-4A) in Nanjing, Yangtze River Delta area of China. We observed strong diurnal and day-to-day variations of fluorescent aerosol particles (FAPs). The average number concentrations of FAPs (1-15 µm) detected in the three WIBS measurement channels (FL1: 0.6 cm-3, FL2: 3.4 cm-3, FL3: 2.1 cm-3) were much higher than those observed in forests and rural areas, suggesting that FAPs other than bioaerosols were detected. We found that the number fractions of FAPs were positively correlated with the black carbon mass fraction, especially for the FL1 channel, indicating a large contribution of combustion-related aerosols. To distinguish bioaerosols from combustion-related FAPs, we investigated two classification schemes for use with WIBS data. Our analysis suggests a strong size dependence for the fractional contributions of different types of FAPs. In the FL3 channel, combustion-related particles seem to dominate the 1-2 µm size range while bioaerosols dominate the 2-5 µm range. The number fractions of combustion-related particles and non-combustion-related particles to total aerosol particles were ˜ 11 and ˜ 5 %, respectively.

  3. Contact nucleation of ice induced by biological aerosol particles

    NASA Astrophysics Data System (ADS)

    Kiselev, Alexei; Hoffmann, Nadine; Schaefer, Manfred; Duft, Denis; Leisner, Thomas

    2014-05-01

    contact freezing in an electrodynamic balance Atmos. Meas. Tech., 6, 2373-2382, 2013. [2] - Hoffmann, N., Duft, D., Kiselev, A., and Leisner, T.: Contact freezing efficiency of mineral dust aerosols studied in an electrodynamic balance: quantitative size and temperature dependence for illite particles, Faraday Discuss., 2013.

  4. Impact of new particle formation on the concentrations of aerosol number and cloud condensation nuclei around Beijing

    SciTech Connect

    Matsui, H.; Koike, Makoto; Kondo, Yutaka; Takegawa, Nobuyuki; Wiedensohler, A.; Fast, Jerome D.; Zaveri, Rahul A.

    2011-10-13

    New particle formation (NPF) is one of the most important processes in controlling the concentrations of aerosol number (condensation nuclei, CN) and cloud condensation nuclei (CCN) in the atmosphere. In this study, we introduced a new aerosol model representation with 20 size bins between 1 nm and 10 {mu}m and activation-type and kinetic nucleation parameterizations into the WRF-chem model (called NPF-explicit WRF-chem). Model calculations were conducted in the Beijing region in China for the periods during the CARE-Beijing 2006 campaign conducted in August and September 2006. Model calculations successfully reproduced the timing of NPF and no-NPF days in the measurements (21 of 26 days). Model calculations also reproduced the subsequent rapid growth of new particles with a time scale of half a day. These results suggest that once a reasonable nucleation rate at a diameter of 1 nm is given, explicit calculations of condensation and coagulation processes can reproduce the clear contrast between NPF and no-NPF days as well as further growth up to several tens nanometers. With this reasonable representation of the NPF process, we show that NPF contributed 20-30% of CN concentrations (> 10 nm in diameter) in and around Beijing on average. We also show that NPF increases CCN concentrations at higher supersaturations (S > 0.2%), while it decreases them at lower supersaturations (S < 0.1%). This is likely because NPF suppresses the increases in both the size and hygroscopicity of pre-existing particles through the competition of condensable gases between new particles and pre-existing particles. Sensitivity calculations show that a reduction of primary aerosol emissions, such as black carbon (BC), would not necessarily decrease CCN concentrations because of an increase in NPF. Sensitivity calculations also suggest that the reduction ratio of primary aerosol and SO2 emissions will be key in enhancing or damping the BC mitigation effect.

  5. Mixing state of ambient aerosols in Nanjing city by single particle mass spectrometry

    NASA Astrophysics Data System (ADS)

    Wang, Honglei; An, Junlin; Shen, Lijuan; Zhu, Bin; Xia, Li; Duan, Qing; Zou, Jianan

    2016-05-01

    To investigate the mixing state and size-resolved aerosol in Nanjing, measurements were carried out for the period 14th January-1st February 2013 by using a Single Particle Aerosol Mass Spectrometer (SPAMS). A total of 10,864,766 particles were sized with vacuum aerodynamic diameter (dva) in the range of 0.2-2.0 μm. Of which, 1,989,725 particles were successfully ionized. Aerosol particles employed for analyzing SPAMS data utilized 96% of the hit particles to identify 5 main particle groups. The particle classes include: K-rich particles (K-CN, K-Nitrate, K-Sulfate and K-Secondary), sodium particles, ammonium particles, carbon-rich particles (OC, EC and OCEC) and heavy-metal particles (Fe-Secondary, Pb-Nitrate, Cu-Mn-Secondary and V-Secondary). EC was the largest contributor with a fraction of 21.78%, followed by K-Secondary (17.87%), K-Nitrate (12.68%) and K-CN (11.25%). High particle level and high RH (relative humidity) are two important factors decreasing visibility in Nanjing. Different particle classes have distinct extinction effects. It anti-correlated well with visibility for the K-secondary, sodium, ammonium, EC, Fe-Secondary and K-Nitrate particles. The proportion of EC particles at 0.65-1.4 μm was up to 25% on haze days and was below 10% on clean days.

  6. Evaluating the applicability of a semi-continuous aerosol sampler to measure Asian dust particles.

    PubMed

    Son, Se-Chang; Park, Seung Shik

    2015-03-01

    A Korean prototype semi-continuous aerosol sampler was used to measure Asian dust particles. During two dust-storm periods, concentrations of crustal and trace elements were significantly enriched. Dust storms are one of the most significant natural sources of air pollution in East Asia. The present study aimed to evaluate use of a Korean semi-continuous aerosol sampler (K-SAS) in observation of mineral dust particles during dust storm events. Aerosol slurry samples were collected at 60 min intervals using the K-SAS, which was operated at a sampling flow rate of 16.7 L min(-1) through a PM10 cyclone inlet. The measurements were made during dust storm events at an urban site, Gwangju in Korea, between April 30 and May 5, 2011. The K-SAS uses particle growth technology as a means of collecting atmospheric aerosol particles. Concentrations of 16 elements (Al, Fe, Mn, Ca, K, Cu, Zn, Pb, Cd, Cr, Ti, V, Ni, Co, As, and Se) were determined off-line in the collected slurry samples by inductively coupled plasma-mass spectrometry (ICP-MS). The sampling periods were classified into two types, based on the source regions of the dust storms and the transport pathways of the air masses reaching the sampling site. The first period "A" was associated with dust particles with high Ca content, originating from the Gobi desert regions of northern China and southern Mongolia. The second period "B" was associated with dust particles with low Ca content, originating from northeastern Chinese sandy deserts. The results from the K-SAS indicated noticeable differences in concentrations of crustal and trace elements in the two sampling periods, as a result of differences in the source regions of the dust storms, the air mass transport pathways, and the impact of smoke from forest fires. The concentrations of the crustal (Al, Ca, Ti, Mn, and Fe) and anthropogenic trace elements (Vi, Ni, Cu, Zn, As, Se, and Pb) were enriched significantly during the two dust storm periods. However, the

  7. Evaluating the applicability of a semi-continuous aerosol sampler to measure Asian dust particles.

    PubMed

    Son, Se-Chang; Park, Seung Shik

    2015-03-01

    A Korean prototype semi-continuous aerosol sampler was used to measure Asian dust particles. During two dust-storm periods, concentrations of crustal and trace elements were significantly enriched. Dust storms are one of the most significant natural sources of air pollution in East Asia. The present study aimed to evaluate use of a Korean semi-continuous aerosol sampler (K-SAS) in observation of mineral dust particles during dust storm events. Aerosol slurry samples were collected at 60 min intervals using the K-SAS, which was operated at a sampling flow rate of 16.7 L min(-1) through a PM10 cyclone inlet. The measurements were made during dust storm events at an urban site, Gwangju in Korea, between April 30 and May 5, 2011. The K-SAS uses particle growth technology as a means of collecting atmospheric aerosol particles. Concentrations of 16 elements (Al, Fe, Mn, Ca, K, Cu, Zn, Pb, Cd, Cr, Ti, V, Ni, Co, As, and Se) were determined off-line in the collected slurry samples by inductively coupled plasma-mass spectrometry (ICP-MS). The sampling periods were classified into two types, based on the source regions of the dust storms and the transport pathways of the air masses reaching the sampling site. The first period "A" was associated with dust particles with high Ca content, originating from the Gobi desert regions of northern China and southern Mongolia. The second period "B" was associated with dust particles with low Ca content, originating from northeastern Chinese sandy deserts. The results from the K-SAS indicated noticeable differences in concentrations of crustal and trace elements in the two sampling periods, as a result of differences in the source regions of the dust storms, the air mass transport pathways, and the impact of smoke from forest fires. The concentrations of the crustal (Al, Ca, Ti, Mn, and Fe) and anthropogenic trace elements (Vi, Ni, Cu, Zn, As, Se, and Pb) were enriched significantly during the two dust storm periods. However, the

  8. Influence of crustal dust and sea spray supermicron particle concentrations and acidity on inorganic NO3− aerosol during the 2013 Southern Oxidant and Aerosol Study

    DOE PAGES

    Allen, H. M.; Draper, D. C.; Ayres, B. R.; Ault, A.; Bondy, A.; Takahama, S.; Modini, R. L.; Baumann, K.; Edgerton, E.; Knote, C.; et al

    2015-09-25

    Inorganic aerosol composition was measured in the southeastern United States, a region that exhibits high aerosol mass loading during the summer, as part of the 2013 Southern Oxidant and Aerosol Study (SOAS) campaign. Measurements using a Monitor for AeRosols and GAses (MARGA) revealed two periods of high aerosol nitrate (NO3−) concentrations during the campaign. These periods of high nitrate were correlated with increased concentrations of supermicron crustal and sea spray aerosol species, particularly Na+ and Ca2+, and with a shift towards aerosol with larger (1 to 2.5 μm) diameters. We suggest this nitrate aerosol forms by multiphase reactions of HNO3more » and particles, reactions that are facilitated by transport of crustal dust and sea spray aerosol from a source within the United States. The observed high aerosol acidity prevents the formation of NH4NO3, the inorganic nitrogen species often dominant in fine-mode aerosol at higher pH. In addition, calculation of the rate of the heterogeneous uptake of HNO3 on mineral aerosol supports the conclusion that aerosol NO3− is produced primarily by this process, and is likely limited by the availability of mineral cation-containing aerosol surface area. Modeling of NO3− and HNO3 by thermodynamic equilibrium models (ISORROPIA II and E-AIM) reveals the importance of including mineral cations in the southeastern United States to accurately balance ion species and predict gas–aerosol phase partitioning.« less

  9. Bacterial Colonization of Particles: Growth and Interactions

    PubMed Central

    Grossart, Hans-Peter; Kiørboe, Thomas; Tang, Kam; Ploug, Helle

    2003-01-01

    Marine particles in the ocean are exposed to diverse bacterial communities, and colonization and growth of attached bacteria are important processes in the degradation and transformation of the particles. In an earlier study, we showed that the initial colonization of model particles by individual bacterial strains isolated from marine aggregates was a function of attachment and detachment. In the present study, we have investigated how this colonization process was further affected by growth and interspecific interactions among the bacteria. Long-term incubation experiments showed that growth dominated over attachment and detachment after a few hours in controlling the bacterial population density on agar particles. In the absence of grazing mortality, this growth led to an equilibrium population density consistent with the theoretical limit due to oxygen diffusion. Interspecific interaction experiments showed that the presence of some bacterial strains (“residents”) on the agar particles either increased or decreased the colonization rate of other strains (“newcomers”). Comparison between an antibiotic-producing strain and its antibiotic-free mutant showed no inhibitory effect on the newcomers due to antibiotic production. On the contrary, hydrolytic activity of the antibiotic-producing strain appeared to benefit the newcomers and enhance their colonization rate. These results show that growth- and species-specific interactions have to be taken into account to adequately describe bacterial colonization of marine particles. Changes in colonization pattern due to such small-scale processes may have profound effects on the transformation and fluxes of particulate matter in the ocean. PMID:12788756

  10. Bacterial colonization of particles: growth and interactions.

    PubMed

    Grossart, Hans-Peter; Kiørboe, Thomas; Tang, Kam; Ploug, Helle

    2003-06-01

    Marine particles in the ocean are exposed to diverse bacterial communities, and colonization and growth of attached bacteria are important processes in the degradation and transformation of the particles. In an earlier study, we showed that the initial colonization of model particles by individual bacterial strains isolated from marine aggregates was a function of attachment and detachment. In the present study, we have investigated how this colonization process was further affected by growth and interspecific interactions among the bacteria. Long-term incubation experiments showed that growth dominated over attachment and detachment after a few hours in controlling the bacterial population density on agar particles. In the absence of grazing mortality, this growth led to an equilibrium population density consistent with the theoretical limit due to oxygen diffusion. Interspecific interaction experiments showed that the presence of some bacterial strains ("residents") on the agar particles either increased or decreased the colonization rate of other strains ("newcomers"). Comparison between an antibiotic-producing strain and its antibiotic-free mutant showed no inhibitory effect on the newcomers due to antibiotic production. On the contrary, hydrolytic activity of the antibiotic-producing strain appeared to benefit the newcomers and enhance their colonization rate. These results show that growth- and species-specific interactions have to be taken into account to adequately describe bacterial colonization of marine particles. Changes in colonization pattern due to such small-scale processes may have profound effects on the transformation and fluxes of particulate matter in the ocean.

  11. Particle size distribution of the stratospheric aerosol from SCIAMACHY limb measurements

    NASA Astrophysics Data System (ADS)

    Rozanov, Alexei; Malinina, Elizaveta; Rozanov, Vladimir; Hommel, Rene; Burrows, John

    2016-04-01

    Stratospheric aerosols are of a great scientific interest because of their crucial role in the Earth's radiative budget as well as their contribution to chemical processes resulting in ozone depletion. While the permanent aerosol background in the stratosphere is determined by the tropical injection of SO2, COS and sulphate particles from the troposphere, major perturbations of the stratospheric aerosol layer result form an uplift of SO2 after strong volcanic eruptions. Satellite measurements in the visible spectral range represent one of the most important sources of information about the vertical distribution of the stratospheric aerosol on the global scale. This study employs measurements of the scattered solar light performed in the limb viewing geometry from the space borne spectrometer SCIAMACHY, which operated onboard the ENVISAT satellite, from August 2002 to April 2012. A retrieval approach to obtain parameters of the stratospheric aerosol particle size distribution will be reported along with the sensitivity studies and first results.

  12. Microspectroscopic Analysis of Anthropogenic- and Biogenic-Influenced Aerosol Particles during the SOAS Field Campaign

    NASA Astrophysics Data System (ADS)

    Ault, A. P.; Bondy, A. L.; Nhliziyo, M. V.; Bertman, S. B.; Pratt, K.; Shepson, P. B.

    2013-12-01

    During the summer, the southeastern United States experiences a cooling haze due to the interaction of anthropogenic and biogenic aerosol sources. An objective of the summer 2013 Southern Oxidant and Aerosol Study (SOAS) was to improve our understanding of how trace gases and aerosols are contributing to this relative cooling through light scattering and absorption. To improve understanding of biogenic-anthropogenic interactions through secondary organic aerosol (SOA) formation on primary aerosol cores requires detailed physicochemical characterization of the particles after uptake and processing. Our measurements focus on single particle analysis of aerosols in the accumulation mode (300-1000 nm) collected using a multi orifice uniform deposition impactor (MOUDI) at the Centreville, Alabama SEARCH site. Particles were characterized using an array of microscopic and spectroscopic techniques, including: scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), and Raman microspectroscopy. These analyses provide detailed information on particle size, morphology, elemental composition, and functional groups. This information is combined with mapping capabilities to explore individual particle spatial patterns and how that impacts structural characteristics. The improved understanding will be used to explore how sources and processing (such as SOA coating of soot) change particle structure (i.e. core shell) and how the altered optical properties impact air quality/climate effects on a regional scale.

  13. Aerosolization, Chemical Characterization, Hygroscopicity and Ice Formation of Marine Biogenic Particles

    NASA Astrophysics Data System (ADS)

    Alpert, P. A.; Radway, J.; Kilthau, W.; Bothe, D.; Knopf, D. A.; Aller, J. Y.

    2013-12-01

    The oceans cover the majority of the earth's surface, host nearly half the total global primary productivity and are a major source of atmospheric aerosol particles. However, effects of biological activity on sea spray generation and composition, and subsequent cloud formation are not well understood. Our goal is to elucidate these effects which will be particularly important over nutrient rich seas, where microorganisms can reach concentrations of 10^9 per mL and along with transparent exopolymer particles (TEP) can become aerosolized. Here we report the results of mesocosm experiments in which bubbles were generated by two methods, either recirculating impinging water jets or glass frits, in natural or artificial seawater containing bacteria and unialgal cultures of three representative phytoplankton species, Thalassiosira pseudonana, Emiliania huxleyi, and Nannochloris atomus. Over time we followed the size distribution of aerosolized particles as well as their hygroscopicity, heterogeneous ice nucleation potential, and individual physical-chemical characteristics. Numbers of cells and the mass of dissolved and particulate organic carbon (DOC, POC), TEP (which includes polysaccharide-containing microgels and nanogels >0.4 μm in diameter) were determined in the bulk water, the surface microlayer, and aerosolized material. Aerosolized particles were also impacted onto substrates for ice nucleation and water uptake experiments, elemental analysis using computer controlled scanning electron microscopy and energy dispersive analysis of X-rays (CCSEM/EDX), and determination of carbon bonding with scanning transmission X-ray microscopy and near-edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS). Regardless of bubble generation method, the overall concentration of aerosol particles, TEP, POC and DOC increased as concentrations of bacterial and phytoplankton cells increased, stabilized, and subsequently declined. Particles <100 nm generated by means of jets

  14. The chemical composition of fine ambient aerosol particles in the Beijing area

    NASA Astrophysics Data System (ADS)

    Nekat, Bettina; van Pinxteren, Dominik; Iinuma, Yoshiteru; Gnauk, Thomas; Müller, Konrad; Herrmann, Hartmut

    2010-05-01

    The strong economical growth in China during the last few decades led to heavy air pollution caused by significantly increased particle emissions. The aerosol particles affect not only the regional air quality and visibility, but can also influence cloud formation processes and the radiative balance of the atmosphere by their optical and microphysical properties. The ability to act as Cloud Condensation Nuclei (CCN) is related to microphysical properties like the hygroscopic growth or the cloud droplet activation. The chemical composition of CCN plays an important role on these properties and varies strongly with the particle size and the time of day. Hygroscopic or surface active substances can increase the hygroscopicity and lower the surface tension of the particle liquid phase, respectively. The presence of such compounds may result in faster cloud droplet activation by faster water uptake. The DFG project HaChi (Haze in China) aimed at studying physical and chemical parameters of urban aerosol particles in the Beijing area in order to associate the chemical composition of aerosol particles with their ability to act as CCN. To this end, two measurement campaigns were performed at the Wuqing National Ordinary Meteorological Observing Station, which is a background site near Beijing. The winter campaign was realized in March 2009 and the summer campaign took place from mid July 2009 to mid August 2009. Fine particles with an aerodynamic diameter smaller than or equal 1 μm were continuously sampled for 24h over the two campaigns using a DIGITEL high volume sampler (DHA-80). The present contribution presents and discusses the results of the chemical characterization of the DIGITEL filters samples. The filters were analyzed for the mass concentration, inorganic ions and carbon sum parameters like elemental (EC), organic (OC) and water soluble organic carbon (WSOC). The WSOC fraction was further characterized for hygroscopic substances like low molecular

  15. Vertical Transport of Aerosol Particles across Mountain Topography near the Los Angeles Basin

    NASA Astrophysics Data System (ADS)

    Murray, J. J.; Schill, S.; Freeman, S.; Bertram, T. H.; Lefer, B. L.

    2015-12-01

    Transport of aerosol particles is known to affect air quality and is largely dependent on the characteristic topography of the surrounding region. To characterize this transport, aerosol number distributions were collected with an Ultra-High Sensitivity Aerosol Spectrometer (UHSAS, DMT) during the 2015 NASA Student Airborne Research Program (SARP) in and around the Los Angeles Basin in Southern California. Increases in particle number concentration and size were observed over mountainous terrain north of Los Angeles County. Chemical analysis and meteorological lagrangian trajectories suggest orographic lifting processes, known as the "chimney effect". Implications for spatial transport and distribution will be discussed.

  16. The effect of aerosol vertical profiles on satellite-estimated surface particle sulfate concentrations

    SciTech Connect

    Liu, Yang; Wang, Zifeng; Wang, Jun; Ferrare, Richard A.; Newsom, Rob K.; Welton, Ellsworth J.

    2011-02-15

    The aerosol vertical distribution is an important factor in determining the relationship between satellite retrieved aerosol optical depth (AOD) and ground-level fine particle pollution concentrations. We evaluate how aerosol profiles measured by ground-based lidar and simulated by models can help improve the association between AOD retrieved by the Multi-angle Imaging Spectroradiometer (MISR) and fine particle sulfate (SO4) concentrations using matched data at two lidar sites. At the Goddard Space Flight Center (GSFC) site, both lidar and model aerosol profiles marginally improve the association between SO4 concentrations and MISR fractional AODs, as the correlation coefficient between cross-validation (CV) and observed SO4 concentrations changes from 0.87 for the no-scaling model to 0.88 for models scaled with aerosol vertical profiles. At the GSFC site, a large amount of urban aerosols resides in the well-mixed boundary layer so the column fractional AODs are already excellent indicators of ground-level particle pollution. In contrast, at the Atmospheric Radiation Measurement Program (ARM) site with relatively low aerosol loadings, scaling substantially improves model performance. The correlation coefficient between CV and observed SO4 concentrations is increased from 0.58 for the no-scaling model to 0.76 in the GEOS-Chem scaling model, and the model bias is reduced from 17% to 9%. In summary, despite the inaccuracy due to the coarse horizontal resolution and the challenges of simulating turbulent mixing in the boundary layer, GEOS-Chem simulated aerosol profiles can still improve methods for estimating surface aerosol (SO4) mass from satellite-based AODs, particularly in rural areas where aerosols in the free troposphere and any long-range transport of aerosols can significantly contribute to the column AOD.

  17. Transmission electron microscopy study of aerosol particles from the brown hazes in northern China

    NASA Astrophysics Data System (ADS)

    Li, Weijun; Shao, Longyi

    2009-05-01

    Airborne aerosol collections were performed in urban areas of Beijing that were affected by regional brown haze episodes over northern China from 31 May to 12 June 2007. Morphologies, elemental compositions, and mixing states of 810 individual aerosol particles of different sizes were obtained by transmission electron microscopy coupled with energy-dispersive X-ray spectrometry. The phases of some particles were verified using selected-area electron diffraction. Aerosol particle types less than 10 μm in diameter include mineral, complex secondary (Ca-S, K-, and S-rich), organic, soot, fly ash, and metal (Fe-rich and Zn-bearing). Most soot, fly ash, and organic particles are less than 2 μm in diameter. Approximately 84% of the analyzed mineral particles have diameters between 2 and 10 μm, while 81% of the analyzed complex secondary and metal particles are much smaller, from 0.1 to 2 μm. Trajectory analysis with fire maps show that southerly air masses arriving at Beijing have been transported through many agricultural biomass burning sites and heavy industrial areas. Spherical fly ash and Fe-rich particles were from industrial emissions, and abundant K-rich and organic particles likely originated from field burning of crop residues. Abundant Zn-bearing particles are associated with industrial activities and local waste incinerators. On the basis of the detailed analysis of 443 analyzed aerosol particles, about 70% of these particles are internally mixed with two or more aerosol components from different sources. Most mineral particles are covered with visible coatings that contain N, O, Ca (or Mg), minor S, and Cl. K- and S-rich particles tend to be coagulated with fly ash, soot, metal, and fine-grained mineral particles. Organic materials internally mixed with K- and S-rich particles can be their inclusions and coatings.

  18. Single-particle measurements of phase partitioning between primary and secondary organic aerosols.

    PubMed

    Robinson, Ellis Shipley; Donahue, Neil M; Ahern, Adam T; Ye, Qing; Lipsky, Eric

    2016-07-18

    Organic aerosols provide a measure of complexity in the urban atmosphere. This is because the aerosols start as an external mixture, with many populations from varied local sources, that all interact with each other, with background aerosols, and with condensing vapors from secondary organic aerosol formation. The externally mixed particle populations start to evolve immediately after emission because the organic molecules constituting the particles also form thermodynamic mixtures - solutions - in which a large fraction of the constituents are semi-volatile. The external mixtures are thus well out of thermodynamic equilibrium, with very different activities for many constituents, and yet also have the capacity to relax toward equilibrium via gas-phase exchange of semi-volatile vapors. Here we describe experiments employing quantitative single-particle mass spectrometry designed to explore the extent to which various primary organic aerosol particle populations can interact with each other or with secondary organic aerosols representative of background aerosol populations. These methods allow us to determine when these populations will and when they will not mix with each other, and then to constrain the timescales for that mixing.

  19. Identifying Metals as Marker for Waste Burning Aerosol Particles in New Delhi

    NASA Astrophysics Data System (ADS)

    Kumar, Sudhanshu

    2012-07-01

    {Identifying Metals as Marker for Waste Burning Aerosol Particles in New Delhi } Tracing of aerosol sources is an important task helpful for making control strategy, and for climate change study. However, it is a difficult job as aerosols have several sources, involve in complex atmospheric processing, degradation and removal processes. Several approaches have been used for this task, e.g., models, which are based on the input of chemical species; stable- and radio-isotope compositions of certain species; chemical markers in which trace metals are the better options because they persist in atmosphere until the life of a particle. For example, K and Hg are used for biomass and coal burning tracings, respectively. Open waste burning has recently been believed to be a considerable source of aerosols in several mega cities in India and China. To better understand this source contribution in New Delhi aerosols, we have conducted aerosol sampling at a landfill site (Okhla), and in proximity (within 1 km distance) of this site. Aerosol filter samples were acid digested in microwave digestion system and analyzed using inductively coupled plasma -- high resolution mass spectrometry (ICP-HRMS) for getting metal signatures in particles. The metals, e.g., Sn, Sb and As those are found almost negligible in remote aerosols, are maximized in these waste burning aerosols. Sample collected in other location of New Delhi also shows the considerable presence of these metals in particles. Preliminary studies of isotopic ratios of these metals suggested that these metals, especially Sn can be used as marker for tracing the open waste burning sources of aerosols in New Delhi.

  20. Metal and Silicate Particles Including Nanoparticles Are Present in Electronic Cigarette Cartomizer Fluid and Aerosol

    PubMed Central

    Williams, Monique; Villarreal, Amanda; Bozhilov, Krassimir; Lin, Sabrina; Talbot, Prue

    2013-01-01

    Background Electronic cigarettes (EC) deliver aerosol by heating fluid containing nicotine. Cartomizer EC combine the fluid chamber and heating element in a single unit. Because EC do not burn tobacco, they may be safer than conventional cigarettes. Their use is rapidly increasing worldwide with little prior testing of their aerosol. Objectives We tested the hypothesis that EC aerosol contains metals derived from various components in EC. Methods Cartomizer contents and aerosols were analyzed using light and electron microscopy, cytotoxicity testing, x-ray microanalysis, particle counting, and inductively coupled plasma optical emission spectrometry. Results The filament, a nickel-chromium wire, was coupled to a thicker copper wire coated with silver. The silver coating was sometimes missing. Four tin solder joints attached the wires to each other and coupled the copper/silver wire to the air tube and mouthpiece. All cartomizers had evidence of use before packaging (burn spots on the fibers and electrophoretic movement of fluid in the fibers). Fibers in two cartomizers had green deposits that contained copper. Centrifugation of the fibers produced large pellets containing tin. Tin particles and tin whiskers were identified in cartridge fluid and outer fibers. Cartomizer fluid with tin particles was cytotoxic in assays using human pulmonary fibroblasts. The aerosol contained particles >1 µm comprised of tin, silver, iron, nickel, aluminum, and silicate and nanoparticles (<100 nm) of tin, chromium and nickel. The concentrations of nine of eleven elements in EC aerosol were higher than or equal to the corresponding concentrations in conventional cigarette smoke. Many of the elements identified in EC aerosol are known to cause respiratory distress and disease. Conclusions The presence of metal and silicate particles in cartomizer aerosol demonstrates the need for improved quality control in EC design and manufacture and studies on how EC aerosol impacts the health of

  1. Physicochemical characterization of Capstone depleted uranium aerosols II: particle size distributions as a function of time.

    PubMed

    Cheng, Yung Sung; Kenoyer, Judson L; Guilmette, Raymond A; Parkhurst, Mary Ann

    2009-03-01

    The Capstone Depleted Uranium (DU) Aerosol Study, which generated and characterized aerosols containing DU from perforation of armored vehicles with large-caliber DU penetrators, incorporated a sampling protocol to evaluate particle size distributions. Aerosol particle size distribution is an important parameter that influences aerosol transport and deposition processes as well as the dosimetry of the inhaled particles. These aerosols were collected on cascade impactor substrates using a pre-established time sequence following the firing event to analyze the uranium concentration and particle size of the aerosols as a function of time. The impactor substrates were analyzed using proportional counting, and the derived uranium content of each served as input to the evaluation of particle size distributions. Activity median aerodynamic diameters (AMADs) of the particle size distributions were evaluated using unimodal and bimodal models. The particle size data from the impactor measurements were quite variable. Most size distributions measured in the test based on activity had bimodal size distributions with a small particle size mode in the range of between 0.2 and 1.2 microm and a large size mode between 2 and 15 microm. In general, the evolution of particle size over time showed an overall decrease of average particle size from AMADs of 5 to 10 microm shortly after perforation to around 1 microm at the end of the 2-h sampling period. The AMADs generally decreased over time because of settling. Additionally, the median diameter of the larger size mode decreased with time. These results were used to estimate the dosimetry of inhaled DU particles. PMID:19204485

  2. Size Resolved Measurements of Springtime Aerosol Particles over the Northern South China Sea

    NASA Technical Reports Server (NTRS)

    Atwood, Samuel A.; Reid, Jeffrey S.; Kreidenweis, Sonia M.; Cliff, Stephen S.; Zhao, Yongjing; Lin, Neng-Huei; Tsay, Si-Chee; Chu, Yu-Chi; Westphal, Douglas L.

    2012-01-01

    Large sources of aerosol particles and their precursors are ubiquitous in East Asia. Such sources are known to impact the South China Sea (henceforth SCS), a sometimes heavily polluted region that has been suggested as particularly vulnerable to climate change. To help elucidate springtime aerosol transport into the SCS, an intensive study was performed on the remote Dongsha (aka Pratas) Islands Atoll in spring 2010. As part of this deployment, a Davis Rotating-drum Uniform size-cut Monitor (DRUM) cascade impactor was deployed to collect size-resolved aerosol samples at the surface that were analyzed by X-ray fluorescence for concentrations of selected elements. HYSPLIT backtrajectories indicated that the transport of aerosol observed at the surface at Dongsha was occurring primarily from regions generally to the north and east. This observation was consistent with the apparent persistence of pollution and dust aerosol, along with sea salt, in the ground-based dataset. In contrast to the sea-level observations, modeled aerosol transport suggested that the westerly flow aloft (w700 hPa) transported smoke-laden air toward the site from regions from the south and west. Measured aerosol optical depth at the site was highest during time periods of modeled heavy smoke loadings aloft. These periods did not coincide with elevated aerosol concentrations at the surface, although the model suggested sporadic mixing of this free-tropospheric aerosol to the surface over the SCS. A biomass burning signature was not clearly identified in the surface aerosol composition data, consistent with this aerosol type remaining primarily aloft and not mixing strongly to the surface during the study. Significant vertical wind shear in the region also supports the idea that different source regions lead to varying aerosol impacts in different vertical layers, and suggests the potential for considerable vertical inhomogeneity in the SCS aerosol environment.

  3. Low-temperature Bessel beam trap for single submicrometer aerosol particle studies

    SciTech Connect

    Lu, Jessica W.; Chasovskikh, Egor; Stapfer, David; Isenor, Merrill; Signorell, Ruth

    2014-09-01

    We report on a new instrument for single aerosol particle studies at low temperatures that combines an optical trap consisting of two counter-propagating Bessel beams (CPBBs) and temperature control down to 223 K (−50 °C). The apparatus is capable of capturing and stably trapping individual submicrometer- to micrometer-sized aerosol particles for up to several hours. First results from studies of hexadecane, dodecane, and water aerosols reveal that we can trap and freeze supercooled droplets ranging in size from ∼450 nm to 5500 nm (radius). We have conducted homogeneous and heterogeneous freezing experiments, freezing-melting cycles, and evaporation studies. To our knowledge, this is the first reported observation of the freezing process for levitated single submicrometer-sized droplets in air using optical trapping techniques. These results show that a temperature-controlled CPBB trap is an attractive new method for studying phase transitions of individual submicrometer aerosol particles.

  4. Single Particle Fluorescence & Mass Spectrometry for the Detection of Biological Aerosols

    SciTech Connect

    Coffee, K; Riot, V; Woods, B; Steele, P; Gard, E E

    2005-04-25

    Biological Aerosol Mass Spectrometry (BAMS) is an emerging technique for the detection of biological aerosols, which is being developed at Lawrence Livermore National Laboratory. The current system uses several orthogonal analytical methods to improve system selectivity, sensitivity and speed in order to maximize its utility as a biological aerosol detection system with extremely low probability of false alarm and high probability of detection. Our approach is to pre-select particles of interest by size and fluorescence prior to mass spectral analysis. The ability to distinguish biological aerosols from background and to discriminate bacterial spores, vegetative cells, viruses and toxins from one another will be shown. Data from particle standards of known chemical composition will be discussed. Analysis of ambient particles will also be presented.

  5. Particle Characterization and Ice Nucleation Efficiency of Field-Collected Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Wang, B.; Gilles, M. K.; Laskin, A.; Moffet, R.; Nizkorodov, S.; Roedel, T.; Sterckx, L.; Tivanski, A.; Knopf, D. A.

    2011-12-01

    Atmospheric ice formation by heterogeneous nucleation is one of the least understood processes resulting in cirrus and mixed-phase clouds which affect the global radiation budget, the hydrological cycle, and water vapor distribution. In particular, how organic aerosol affect ice nucleation is not well understood. Here we report on heterogeneous ice nucleation from particles collected during the CalNex campaign at the Caltech campus site, Pasadena, on May 19, 2010 at 6am-12pm (A2) and 12pm-6pm (A3) and May 23 at 6am-12pm (B2) and 6pm-12am (B4). The ice nucleation onsets and water uptake were determined as a function of temperature (200-273 K) and relative humidity with respect to ice (RHice). The ice nucleation efficiency was related to the particle chemical composition. Single particle characterization was provided by 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). The STXM/NEXAFS analysis indicates that the morning sample (A2) constitutes organic particles and organic particles with soot and inorganic inclusions. The afternoon sample (A3) is dominated by organic particles with a potentially higher degree of oxidation associated with soot. The B2 sample shows a higher number fraction of magnesium-containing particle indicative of a marine source and ~93% of the particles contained sulfur besides oxygen and carbon as derived from CCSEM/EDX analysis. The B4 sample lacks the strong marine influence and shows higher organic content. Above 230 K, we observed water uptake followed by condensation freezing at mean RH of 93-100% and 89-95% for A2 and A3, respectively. This indicates that the aged A3 particles are efficient ice nuclei (IN) for condensation freezing. Below 230 K A2 and A3 induced deposition ice nucleation between 125-155% RHice (at mean values of 134-150% RHice). The B2 and B4

  6. Airborne observations of aerosol microphysical properties and particle ageing processes in the troposphere above Europe

    NASA Astrophysics Data System (ADS)

    Hamburger, T.; McMeeking, G.; Minikin, A.; Petzold, A.; Coe, H.; Krejci, R.

    2012-12-01

    In-situ measurements of aerosol microphysical properties were performed in May 2008 during the EUCAARI-LONGREX campaign. Two aircraft, the FAAM BAe-146 and DLR Falcon 20, operated from Oberpfaffenhofen, Germany. A comprehensive data set was obtained comprising the wider region of Europe north of the Alps throughout the whole tropospheric column. Prevailing stable synoptic conditions enabled measurements of accumulating emissions inside the continental boundary layer reaching a maximum total number concentration of 19 000 particles cm-3 stp. Ultra-fine particles as indicators for nucleation events were observed within the boundary layer during high pressure conditions and after updraft of emissions induced by frontal passages above 8 km altitude in the upper free troposphere. Aerosol ageing processes during air mass transport are analysed using trajectory analysis. The ratio of particles containing a non-volatile core (250 °C) to the total aerosol number concentration was observed to increase within the first 12 to 48 h from the particle source from 50 to 85% due to coagulation. Aged aerosol also features an increased fraction of accumulation mode particles of approximately 40% of the total number concentration. The presented analysis provides an extensive data set of tropospheric aerosol microphysical properties on a continental scale which can be used for atmospheric aerosol models and comparisons of satellite retrievals.

  7. Influenza virus aerosols in human exhaled breath: particle size, culturability, and effect of surgical masks.

    PubMed

    Milton, Donald K; Fabian, M Patricia; Cowling, Benjamin J; Grantham, Michael L; McDevitt, James J

    2013-03-01

    The CDC recommends that healthcare settings provide influenza patients with facemasks as a means of reducing transmission to staff and other patients, and a recent report suggested that surgical masks can capture influenza virus in large droplet spray. However, there is minimal data on influenza virus aerosol shedding, the infectiousness of exhaled aerosols, and none on the impact of facemasks on viral aerosol shedding from patients with seasonal influenza. We collected samples of exhaled particles (one with and one without a facemask) in two size fractions ("coarse">5 µm, "fine"≤5 µm) from 37 volunteers within 5 days of seasonal influenza onset, measured viral copy number using quantitative RT-PCR, and tested the fine-particle fraction for culturable virus. Fine particles contained 8.8 (95% CI 4.1 to 19) fold more viral copies than did coarse particles. Surgical masks reduced viral copy numbers in the fine fraction by 2.8 fold (95% CI 1.5 to 5.2) and in the coarse fraction by 25 fold (95% CI 3.5 to 180). Overall, masks produced a 3.4 fold (95% CI 1.8 to 6.3) reduction in viral aerosol shedding. Correlations between nasopharyngeal swab and the aerosol fraction copy numbers were weak (r = 0.17, coarse; r = 0.29, fine fraction). Copy numbers in exhaled breath declined rapidly with day after onset of illness. Two subjects with the highest copy numbers gave culture positive fine particle samples. Surgical masks worn by patients reduce aerosols shedding of virus. The abundance of viral copies in fine particle aerosols and evidence for their infectiousness suggests an important role in seasonal influenza transmission. Monitoring exhaled virus aerosols will be important for validation of experimental transmission studies in humans.

  8. Middle East measurements of concentration and size distribution of aerosol particles for coastal zones

    NASA Astrophysics Data System (ADS)

    Bendersky, Sergey; Kopeika, Norman S.; Blaunstein, Natan S.

    2005-10-01

    Recently, an extension of the Navy Aerosol Model (NAM) was proposed based on analysis of an extensive series of measurements at the Irish Atlantic Coast and at the French Mediterranean Coast. We confirm the relevance of that work for the distant eastern Meditteranean and extend several coefficients of that coastal model, proposed by Piazzola et al. for the Meditteranean Coast (a form of the Navy Aerosol Model), to midland Middle East coastal environments. This analysis is based on data collected at three different Middle East coastal areas: the Negev Desert (Eilat) Red Sea Coast, the Sea of Galilee (Tiberias) Coast, and the Mediterranean (Haifa) Coast. Aerosol size distributions are compared with those obtained through measurements carried out over the Atlantic, Pacific, and Indian Ocean Coasts, and Mediterranean, and Baltic Seas Coasts. An analysis of these different results allows better understanding of the similarities and differences between different coastal lake, sea, and open ocean zones. It is shown that in the coastal regions in Israel, compared to open ocean and other sea zones, larger differences in aerosol particle concentration are observed. The aerosol particle concentrations and their dependences on wind speed for these coastal zones are analyzed and discussed. We propose to classify the aerosol distribution models to either: 1. a coastal model with marine aerosol domination; 2. a coastal model with continental aerosol domination (referred to as midland coast in this work); or 3. a coastal model with balanced marine and continental conditions.

  9. Modeling of microphysics and optics of aerosol particles in the marine environments

    NASA Astrophysics Data System (ADS)

    Kaloshin, Gennady

    2013-05-01

    We present a microphysical model for the surface layer marine and coastal atmospheric aerosols that is based on long-term observations of size distributions for 0.01-100 μm particles. The fundamental feature of the model is a parameterization of amplitudes and widths for aerosol modes of the aerosol size distribution function (ASDF) as functions of fetch and wind speed. The shape of ASDF and its dependence on meteorological parameters, height above sea level (H), fetch (X), wind speed (U) and relative humidity (RH), are investigated. At present, the model covers the ranges H = 0 - 25 m, U = 3 - 18 km s-1, X ≤ 120 km and RH = 40 - 98%. The latest version of the Marine Aerosol Extinction Profiles model (MaexPro) is described and applied for the computation and analysis of the spectral profiles of aerosol extinction coefficients α(λ) in the wavelength band λ = 0.2-12 μm. MaexPro is based on the aforementioned aerosol model assuming spherically shaped aerosol particles and the well-known Mie theory. The spectral profiles of α(λ) calculated by MaexPro are in good agreement with observational data and the numerical results. Moreover, MaexPro was found to be an accurate and reliable tool for investigating the optical properties of atmospheric aerosols.

  10. Aerosol Impacts on the Growth of Cumulus Congestus Clouds

    NASA Astrophysics Data System (ADS)

    Sheffield, A. M.; van den Heever, S. C.; Saleeby, S. M.

    2012-12-01

    Tropical convection has been observed to contain three modes of convection, the middle mode of which is cumulus congestus clouds. This study investigates the impacts of aerosol, specifically those aerosols that can serve as cloud condensation nuclei, on the growth and development of congestus clouds observed within idealized cloud-resolving model (CRM) simulations conducted under a state of radiative-convective equilibrium (RCE). The model employed here is the Regional Atmospheric Modeling System (RAMS). RAMS CRM simulations were completed using a large two-dimensional domain (7200 km) at fine resolution (1 km) and long duration (100 days). Results indicate that congestus in more polluted conditions extend to greater heights more frequently than those developing in clean cases. Greater cloud water mass and ice mass forms in more polluted conditions, though ice forms at a fraction of the rate of the cloud mass. The importance of vapor diffusional growth of cloud droplets in the more polluted conditions is highlighted as one such process contributing to congestus development through latent heat release.

  11. Formation of highly porous aerosol particles by atmospheric freeze-drying in ice clouds

    NASA Astrophysics Data System (ADS)

    Rudich, Yinon; Adler, Gabriela; Koop, Thomas; Taraniuk, Ilya; Moise, Tamar; Koren, Ilan; Heiblum, Reuven; Haspel, Carynelisa

    2014-05-01

    In cold high altitude cirrus clouds and anvils of high convective clouds in the tropics and mid-latitudes, ice partciles that are exposed 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. In this talk we will describe experiements that simulate the atmospheric freeze-drying cycle of aerosols. We find that aerosols with high organic content can form highly porous particles (HPA) with a larger diameter and a lower density than the initial homogenous aerosol following ice subliation. 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 follwoing ice sublimation. We find that the highly porous aerosol scatter solar light less efficiently than non-porous aerosol particles. A porous structure may explain the previously observed enhancement in ice nucleation efficiency of glassy organic particles. These observations may have implications for subsequent cloud formation cycles and aerosol albedo near cloud edges.

  12. Measurements of the evaporation and hygroscopic response of single fine-mode aerosol particles using a Bessel beam optical trap.

    PubMed

    Cotterell, Michael I; Mason, Bernard J; Carruthers, Antonia E; Walker, Jim S; Orr-Ewing, Andrew J; Reid, Jonathan P

    2014-02-01

    A single horizontally-propagating zeroth order Bessel laser beam with a counter-propagating gas flow was used to confine single fine-mode aerosol particles over extended periods of time, during which process measurements were performed. Particle sizes were measured by the analysis of the angular variation of light scattered at 532 nm by a particle in the Bessel beam, using either a probe beam at 405 nm or 633 nm. The vapour pressures of glycerol and 1,2,6-hexanetriol particles were determined to be 7.5 ± 2.6 mPa and 0.20 ± 0.02 mPa respectively. The lower volatility of hexanetriol allowed better definition of the trapping environment relative humidity profile over the measurement time period, thus higher precision measurements were obtained compared to those for glycerol. The size evolution of a hexanetriol particle, as well as its refractive index at wavelengths 532 nm and 405 nm, were determined by modelling its position along the Bessel beam propagation length while collecting phase functions with the 405 nm probe beam. Measurements of the hygroscopic growth of sodium chloride and ammonium sulfate have been performed on particles as small as 350 nm in radius, with growth curves well described by widely used equilibrium state models. These are the smallest particles for which single-particle hygroscopicity has been measured and represent the first measurements of hygroscopicity on fine mode and near-accumulation mode aerosols, the size regimes bearing the most atmospheric relevance in terms of loading, light extinction and scattering. Finally, the technique is contrasted with other single particle and ensemble methods, and limitations are assessed.

  13. Measurements of the evaporation and hygroscopic response of single fine-mode aerosol particles using a Bessel beam optical trap.

    PubMed

    Cotterell, Michael I; Mason, Bernard J; Carruthers, Antonia E; Walker, Jim S; Orr-Ewing, Andrew J; Reid, Jonathan P

    2014-02-01

    A single horizontally-propagating zeroth order Bessel laser beam with a counter-propagating gas flow was used to confine single fine-mode aerosol particles over extended periods of time, during which process measurements were performed. Particle sizes were measured by the analysis of the angular variation of light scattered at 532 nm by a particle in the Bessel beam, using either a probe beam at 405 nm or 633 nm. The vapour pressures of glycerol and 1,2,6-hexanetriol particles were determined to be 7.5 ± 2.6 mPa and 0.20 ± 0.02 mPa respectively. The lower volatility of hexanetriol allowed better definition of the trapping environment relative humidity profile over the measurement time period, thus higher precision measurements were obtained compared to those for glycerol. The size evolution of a hexanetriol particle, as well as its refractive index at wavelengths 532 nm and 405 nm, were determined by modelling its position along the Bessel beam propagation length while collecting phase functions with the 405 nm probe beam. Measurements of the hygroscopic growth of sodium chloride and ammonium sulfate have been performed on particles as small as 350 nm in radius, with growth curves well described by widely used equilibrium state models. These are the smallest particles for which single-particle hygroscopicity has been measured and represent the first measurements of hygroscopicity on fine mode and near-accumulation mode aerosols, the size regimes bearing the most atmospheric relevance in terms of loading, light extinction and scattering. Finally, the technique is contrasted with other single particle and ensemble methods, and limitations are assessed. PMID:24346588

  14. Size, composition, and mixing state of individual aerosol particles in a South China coastal city.

    PubMed

    Li, Weijun; Shao, Longyi; Wang, Zhishi; Shen, Rongrong; Yang, Shusheng; Tang, Uwa

    2010-01-01

    Aerosol samples were collected in summer in Macao, a coastal city of the Pearl River Delta Region in China. Morphology, size, elemental composition, and mixing state of individual aerosol particles were determined by scanning electron microscopy coupled energy dispersive X-ray (SEM/EDX) and transmission electron microscopy (TEM). Based on the morphologies of 5711 aerosol particles, they consist of soot (32%), mineral (17%), secondary (22%), and unknown fine particles (29%). The sizes of these particles were mostly distributed between 0.1 and 0.4 microm. Compositions of 202 mineral particles were obtained by SEM/EDX. Mineral particles were mainly classified into three types: Si-rich, Ca-rich, and Na-rich. The compositions of typical mineral particles can indicate their sources in sampling location. For example, mineral particles, collected along the main street, were associated with trace amounts of heavy metals, such as Zn, Ti, Mn, Ba, Pb, and As. TEM observations indicate that most Na-rich particles were aged sea salt particles (e.g., Na2SO4 and NaNO3) which formed through heterogeneous chemical reactions between sea salt and acidic gases. Additionally, aging time of soot was short in Macao due to high humidity, high temperature, and high levels of sunlight in Macao. Most of soot and fine mineral dust particles were internally mixed with secondary particles.

  15. New Particle Formation and Growth from Methanesulfonic Acid, Amines, Water, and Organics

    NASA Astrophysics Data System (ADS)

    Arquero, K. D.; Ezell, M. J.; Finlayson-Pitts, B. J.

    2014-12-01

    Particles in the atmosphere can influence visibility, negatively impact human health, and affect climate. The largest uncertainty in determining global radiative forcing is attributed to atmospheric aerosols. While new particle formation in many locations is correlated with sulfuric acid in air, neither the gas-phase binary nucleation of H2SO4-H2O nor the gas-phase ternary nucleation of H2SO4-NH3-H2O alone can fully explain observations. An additional potential particle source, based on previous studies in this laboratory, is methanesulfonic acid (MSA) with amines and water vapor. However, organics are ubiquitous in the atmosphere, with secondary organic aerosol (SOA) being a major component of particles. Organics could be involved in the initial stages of particle formation by enhancing or inhibiting nucleation from sulfuric acid or MSA, in addition to contributing to their growth to form SOA. Experiments to measure the effects of a series of organics of varying structure on particle formation and growth from MSA, amines, and water were performed in a custom-built small volume aerosol flow tube reactor. Analytical instruments and techniques include a scanning mobility particle sizer to measure particle size distributions, sampling onto a weak cation exchange resin with analysis by ion chromatography to measure amine concentrations, and filter collection and analysis by ultra-high performance liquid chromatography tandem mass spectrometry to measure MSA concentrations. Organics were measured by atmospheric pressure chemical ionization tandem mass spectrometry. The impact of these organics on the initial particle formation as well as growth will be reported. The outcome is an improved understanding of fundamental chemistry of nucleation and growth to ultimately be incorporated into climate models to better predict how particles affect the global climate budget.

  16. Formation characteristics of aerosol particles from pulverized coal pyrolysis in high-temperature environments

    SciTech Connect

    Wei-Hsin Chen; Shan-Wen Du; Hsi-Hsien Yang; Jheng-Syun Wu

    2008-05-15

    The formation characteristics of aerosol particles from pulverized coal pyrolysis in high temperatures are studied experimentally. By conducting a drop-tube furnace, fuel pyrolysis processes in industrial furnaces are simulated in which three different reaction temperatures of 1000, 1200, and 1400{sup o}C are considered. Experimental observations indicate that when the reaction temperature is 1000{sup o}C, submicron particles are produced, whereas the particle size is dominated by nanoscale for the temperature of 1400{sup o}C. Thermogravimetric analysis of the aerosol particles stemming from the pyrolysis temperature of 1000{sup o}C reveals that the thermal behavior of the aerosol is characterized by a three-stage reaction with increasing heating temperature: (1) a volatile-reaction stage, (2) a weak-reaction stage, and (3) a soot-reaction stage. However, with the pyrolysis temperature of 1400{sup o}C, the volatile- and weak-reaction stages almost merge together and evolve into a chemical-frozen stage. The submicron particles (i.e., 1000{sup o}C) are mainly composed of volatiles, tar, and soot, with the main component of the nanoscale particles (i.e., 1400{sup o}C) being soot. The polycyclic aromatic hydrocarbons (PAHs) contained in the aerosols are also analyzed. It is found that the PAH content in generated aerosols decreases dramatically as the pyrolysis temperature increases. 31 refs., 9 figs., 1 tab.

  17. Fluorescence properties of biochemicals in dry NaCl composite aerosol particles and in solutions

    NASA Astrophysics Data System (ADS)

    Putkiranta, M.; Manninen, A.; Rostedt, A.; Saarela, J.; Sorvajärvi, T.; Marjamäki, M.; Hernberg, R.; Keskinen, J.

    2010-06-01

    Several fluorophores, such as tryptophan, NADH, NADPH, and riboflavin are found in airborne micro-organisms. In this work, the fluorescence properties of these biochemicals were studied both in dry NaCl composite aerosol particles and in saline solutions by means of laser-induced fluorescence. Fluorescence spectra were measured from individual, airborne aerosol particles and from solutions in cuvette. The excitation wavelength was varied in steps from 210 nm to 419 nm and the fluorescence was detected within a wavelength band of 310-670 nm. For each sample, the measured fluorescence emission spectra were combined into fluorescence maps. The fluorescence maximum of riboflavin in a dry NaCl composite particle is 20 nm red-shifted compared with the solution, whereas the maxima are blue-shifted by about 25 nm for tryptophan and 15 nm for NADH and NADPH. The molecular fluorescence cross sections have significant differences between the aerosol particles and the solutions, except for tryptophan. For NADH and NADPH the cross sections are over 20 times larger in the aerosol particles than in the solutions probably as a result of partial quenching of fluorescence in solution caused by the collision or stacking with the adenine moiety. The fluorescence cross section of riboflavin is almost 60 times larger in the solution than in the dry NaCl composite aerosol. This is probably caused by the different microenvironment around the fluorophore molecule and by the concentration quenching in the particles where the fluorescing molecules are relatively close to each other.

  18. [Hygroscopic Properties of Aerosol Particles in North Suburb of Nanjing in Spring].

    PubMed

    Xu, Bin; Zhang, Ze-feng; Li, Yan-weil; Qin, Xin; Miao, Qing; Shen, Yan

    2015-06-01

    The hygroscopic properties of submicron aerosol particles have significant effects on spectral distribution, CCN activation, climate forcing, human health and so on. A Hygroscopic Tandem Differential Mobility Analyzer (HTDMA) was utilized to analyze the hygroscopic properties of aerosol particles in the northern suburb of Nanjing during 16 April to 21 May, 2014. At relative humidity (RH) of 90%, for particles with dry diameters 30-230 nm, the probability distribution of GF (GF-PDF) shows a distinct bimodal pattern, with a dominant more-hygroscopic group and a smaller less-hygroscopic group. A contrast analysis between day and night suggests that, aerosol particles during day time have a stronger hygroscopicity and a higher number fraction of more-hygroscopic group than that at night overall. Aerosol particles during night have a higher degree of externally mixed state. Backward trajectory analysis using HYSPLIT mode reveals that, the sampling site is mainly affected by three air masses. For aitken nuclei, northwest continental air masses experience a longer aging process and have a stronger hygroscopicity. For condensation nuclei, east air masses have a stronger hygroscopicity and have a higher number fraction of more-hygroscopic group. Aerosol particles in local air masses have a high number fraction of more-hygroscopic group in the whole diameter range.

  19. Growth of organic aerosols by biogenic semi-volatile carbonyls in the forestal atmosphere

    NASA Astrophysics Data System (ADS)

    Matsunaga, Sou; Mochida, Michihiro; Kawamura, Kimitaka

    Gas and aerosol samples were collected from 13 to 15 August 2001 in Quercus and Picea mixed forest located at Uryu Experimental Forest of Hokkaido University using an annular denuder air sampling system. Gaseous concentrations of biogenic semi-volatile compounds (glycolaldehyde, hydroxyacetone, n-nonanal and n-decanal) showed a rapid increase in the morning and showed a maximum (61-105 pptv) around noontime. Then their concentrations significantly decreased in the evening, and showed a minimum at mid-night. On the other hand, these compounds in the particulate phase also showed a diurnal variation pattern similar to the gaseous compounds. However, the concentrations continued to increase until the evening and showed the maximum at nearly mid-night. The time lag of several hours in the peak of concentrations of these carbonyls in gas phase and particles indicates a gas-to-particle conversion probably through condensation and adsorption of gaseous compounds onto the pre-existing particles (growth of the aerosols).

  20. Airborne observations of aerosol microphysical properties and particle ageing processes in the troposphere above Europe

    NASA Astrophysics Data System (ADS)

    Hamburger, T.; McMeeking, G.; Minikin, A.; Petzold, A.; Coe, H.; Krejci, R.

    2012-08-01

    In-situ measurements of aerosol microphysical properties were performed in May 2008 during the EUCAARI-LONGREX campaign. Two aircraft, the FAAM BAe-146 and DLR Falcon 20, operated from Oberpfaffenhofen, Germany. A comprehensive data set was obtained comprising the wider region of Europe north of the Alps throughout the whole tropospheric column. Prevailing stable synoptic conditions enabled measurements of accumulating emissions inside the continental boundary layer reaching a maximum total number concentration of 19 000 particles cm-3 stp. Nucleation events were observed within the boundary layer during high pressure conditions and after updraft of emissions induced by frontal passages above 8 km altitude in the upper free troposphere. Aerosol ageing processes during air mass transport are analysed using trajectory analysis. The ratio of particles containing a non-volatile core (250 °C) to the total aerosol number concentration was observed to increase within the first 12 to 48 h from the particle source from 50 to 85% due to coagulation. Aged aerosol also features an increased fraction of accumulation mode particles of approximately 40% of the total number concentration. The presented analysis provides an extensive data set of tropospheric aerosol microphysical properties on a continental scale which can be used for atmospheric aerosol models and comparisons of satellite retrievals.

  1. Characterization of a Quadrotor Unmanned Aircraft System for Aerosol-Particle-Concentration Measurements.

    PubMed

    Brady, James M; Stokes, M Dale; Bonnardel, Jim; Bertram, Timothy H

    2016-02-01

    High-spatial-resolution, near-surface vertical profiling of atmospheric chemical composition is currently limited by the availability of experimental platforms that can sample in constrained environments. As a result, measurements of near-surface gradients in trace gas and aerosol particle concentrations have been limited to studies conducted from fixed location towers or tethered balloons. Here, we explore the utility of a quadrotor unmanned aircraft system (UAS) as a sampling platform to measure vertical and horizontal concentration gradients of trace gases and aerosol particles at high spatial resolution (1 m) within the mixed layer (0-100 m). A 3D Robotics Iris+ autonomous quadrotor UAS was outfitted with a sensor package consisting of a two-channel aerosol optical particle counter and a CO2 sensor. The UAS demonstrated high precision in both vertical (±0.5 m) and horizontal positions (±1 m), highlighting the potential utility of quadrotor UAS drones for aerosol- and trace-gas measurements within complex terrain, such as the urban environment, forest canopies, and above difficult-to-access areas such as breaking surf. Vertical profiles of aerosol particle number concentrations, acquired from flights conducted along the California coastline, were used to constrain sea-spray aerosol-emission rates from coastal wave breaking. PMID:26730457

  2. Characterization of a Quadrotor Unmanned Aircraft System for Aerosol-Particle-Concentration Measurements.

    PubMed

    Brady, James M; Stokes, M Dale; Bonnardel, Jim; Bertram, Timothy H

    2016-02-01

    High-spatial-resolution, near-surface vertical profiling of atmospheric chemical composition is currently limited by the availability of experimental platforms that can sample in constrained environments. As a result, measurements of near-surface gradients in trace gas and aerosol particle concentrations have been limited to studies conducted from fixed location towers or tethered balloons. Here, we explore the utility of a quadrotor unmanned aircraft system (UAS) as a sampling platform to measure vertical and horizontal concentration gradients of trace gases and aerosol particles at high spatial resolution (1 m) within the mixed layer (0-100 m). A 3D Robotics Iris+ autonomous quadrotor UAS was outfitted with a sensor package consisting of a two-channel aerosol optical particle counter and a CO2 sensor. The UAS demonstrated high precision in both vertical (±0.5 m) and horizontal positions (±1 m), highlighting the potential utility of quadrotor UAS drones for aerosol- and trace-gas measurements within complex terrain, such as the urban environment, forest canopies, and above difficult-to-access areas such as breaking surf. Vertical profiles of aerosol particle number concentrations, acquired from flights conducted along the California coastline, were used to constrain sea-spray aerosol-emission rates from coastal wave breaking.

  3. Particle-Resolved Modeling of Aerosol Mixing State in an Evolving Ship Plume

    NASA Astrophysics Data System (ADS)

    Riemer, N. S.; Tian, J.; Pfaffenberger, L.; Schlager, H.; Petzold, A.

    2011-12-01

    The aerosol mixing state is important since it impacts the particles' optical and CCN properties and thereby their climate impact. It evolves continuously during the particles' residence time in the atmosphere as a result of coagulation with other particles and condensation of secondary aerosol species. This evolution is challenging to represent in traditional aerosol models since they require the representation of a multi-dimensional particle distribution. While modal or sectional aerosol representations cannot practically resolve the aerosol mixing state for more than a few species, particle-resolved models store the composition of many individual aerosol particles directly. They thus sample the high-dimensional composition state space very efficiently and so can deal with tens of species, fully resolving the mixing state. Here we use the capabilities of the particle-resolved model PartMC-MOSAIC to simulate the evolution of particulate matter emitted from marine diesel engines and compare the results to aircraft measurements made in the English Channel in 2007 as part of the European campaign QUANTIFY. The model was initialized with values of gas concentrations and particle size distributions and compositions representing fresh ship emissions. These values were obtained from a test rig study in the European project HERCULES in 2006 using a serial four-stroke marine diesel engine operating on high-sulfur heavy fuel oil. The freshly emitted particles consisted of sulfate, black carbon, organic carbon and ash. We then tracked the particle population for several hours as it evolved undergoing coagulation, dilution with the background air, and chemical transformations in the aerosol and gas phase. This simulation was used to compute the evolution of CCN properties and optical properties of the plume on a per-particle basis. We compared our results to size-resolved data of aged ship plumes from the QUANTIFY Study in 2007 and showed that the model was able to reproduce

  4. Investigation of Aerosol Surface Area Estimation from Number and Mass Concentration Measurements: Particle Density Effect

    PubMed Central

    Ku, Bon Ki; Evans, Douglas E.

    2015-01-01

    For nanoparticles with nonspherical morphologies, e.g., open agglomerates or fibrous particles, it is expected that the actual density of agglomerates may be significantly different from the bulk material density. It is further expected that using the material density may upset the relationship between surface area and mass when a method for estimating aerosol surface area from number and mass concentrations (referred to as “Maynard’s estimation method”) is used. Therefore, it is necessary to quantitatively investigate how much the Maynard’s estimation method depends on particle morphology and density. In this study, aerosol surface area estimated from number and mass concentration measurements was evaluated and compared with values from two reference methods: a method proposed by Lall and Friedlander for agglomerates and a mobility based method for compact nonspherical particles using well-defined polydisperse aerosols with known particle densities. Polydisperse silver aerosol particles were generated by an aerosol generation facility. Generated aerosols had a range of morphologies, count median diameters (CMD) between 25 and 50 nm, and geometric standard deviations (GSD) between 1.5 and 1.8. The surface area estimates from number and mass concentration measurements correlated well with the two reference values when gravimetric mass was used. The aerosol surface area estimates from the Maynard’s estimation method were comparable to the reference method for all particle morphologies within the surface area ratios of 3.31 and 0.19 for assumed GSDs 1.5 and 1.8, respectively, when the bulk material density of silver was used. The difference between the Maynard’s estimation method and surface area measured by the reference method for fractal-like agglomerates decreased from 79% to 23% when the measured effective particle density was used, while the difference for nearly spherical particles decreased from 30% to 24%. The results indicate that the use of

  5. Molecular constraints on particle growth during new particle formation

    NASA Astrophysics Data System (ADS)

    Bzdek, Bryan R.; Lawler, Michael J.; Horan, Andrew J.; Pennington, M. Ross; DePalma, Joseph W.; Zhao, Jun; Smith, James N.; Johnston, Murray V.

    2014-08-01

    Atmospheric new particle formation (NPF) produces large numbers of nanoparticles which can ultimately impact climate. A firm understanding of the identity and contribution of the inorganic and carbonaceous species to nanoparticle growth is required to assess the climatic importance of NPF. Here, we combine elemental and molecular nanoparticle composition measurements to better define the composition and contribution of carbonaceous matter to nanoparticle growth in a rural/coastal environment. We show that carbonaceous matter can account for more than half of the mass growth of nanoparticles and its composition is consistent with that expected for extremely low volatility organic compounds. An important novel finding is that the carbonaceous matter must contain a substantial amount of nitrogen, whose molecular identity is not fully understood. The results advance our quantitative understanding of the composition and contribution of carbonaceous matter to nanoparticle growth, which is essential to more accurately predict the climatic impacts of NPF.

  6. Mapping of soot particles in a weakly sooting diffusion flame by aerosol techniques

    SciTech Connect

    Hepp, H.; Siegmann, K.

    1998-10-01

    The evolution of detailed particle size distributions has been measured along the centerline of an axisymmetric diffusion flame of CH{sub 4} + Ar burning in air at 1 atm. Soot particles with mean diameters of 3--18 nm were observed. Changes in the size distribution exhibited zones where either nucleation, coagulation, or destruction of soot particles dominated. These highly sensitive measurements were made by microprobe sampling with an immediate dilution of 1:400, to quench the aerosol, and by subsequent application of aerosol measurement techniques. In parallel, the yield of photoemitted electrons from size-selected particles was determined. The yield shows a characteristic dependence on location in the flame, indicating changes of the particle`s surface. Multiphoton, time-of-flight mass spectrometry was used to investigate the correlation between polycyclic aromatic hydrocarbons in the flame and enhanced photoemission yield from the soot particles.

  7. Experimental Assessment of Collection Efficiency of Submicron Aerosol Particles by Cloud Droplets

    NASA Astrophysics Data System (ADS)

    Huang, Y. W.; Ardon-Dryer, K.; Cziczo, D. J.

    2014-12-01

    The interplay between aerosol particles and water droplets in the atmosphere, especially in clouds, influences both aerosol and cloud properties. The major uncertainty in our understanding of climate arises in the indirect effect of aerosol and their ability to impact cloud formation and consequently alter the global radiative balance. The collision between a water droplet and aerosol particles that results in coalescence is termed "collection" or "coagulation". Coagulation can lead to aerosol removal from the atmosphere or induce ice nucleation via contact freezing. There is a theoretical collection efficiency minimum of particles with diameter between 0.1-2 µm, called the "Greenfield Gap". Experimental effort, however, was limited to drizzle and rain drops until recently, and has not constrained parameters that describe particle collection efficiency by cloud droplets. Collection efficiency is also an important parameter for assessing contact freezing, the least known ice nucleation mechanism today. Experimentally assessing collection efficiency can prove the existence of the "Greenfield Gap" and lay the foundation for studying contact freezing. We recently constructed the MIT-Contact Freezing Chamber (MIT-CFC) to study coagulation experimentally. A stream of 40 µm cloud droplets fall freely into the chamber and collide with aerosol particles with known size and concentration. The outflow goes through a series of dryers before entering the Particle Analysis by Laser Mass Spectrometry (PALMS) instrument for chemical composition analysis. PALMS is a true single-particle instrument and gives information on the size and the chemical composition of each particle. Coagulated particles from the MIT-CFC have mass spectral signatures of both the aerosol particles and the droplet residuals, while the droplet residual contains no signature of the aerosol particles. To our knowledge, this is the first time coagulation has been seen on a single-particle basis. We will

  8. HUMIDITY EFFECTS ON THE MASS SPECTRA OF SINGLE AEROSOL PARTICLES. (R823980)

    EPA Science Inventory

    On-line laser desorption ionization mass spectrometry has developed into a widely used method for chemical characterization of individual aerosol particles. In the present study, the spectra of laboratory-generated particles were obtained as a function of relative humidity to elu...

  9. Glyoxal processing by aerosol multiphase chemistry: towards a kinetic modeling framework of secondary organic aerosol formation in aqueous particles

    NASA Astrophysics Data System (ADS)

    Ervens, B.; Volkamer, R.

    2010-09-01

    This study presents a modeling framework based on laboratory data to describe the kinetics of glyoxal reactions that form secondary organic aerosol (SOA) in aqueous aerosol particles. Recent laboratory results on glyoxal reactions are reviewed and a consistent set of empirical reaction rate constants is derived that captures the kinetics of glyoxal hydration and subsequent reversible and irreversible reactions in aqueous inorganic and water-soluble organic aerosol seeds. Products of these processes include (a) oligomers, (b) nitrogen-containing products, (c) photochemical oxidation products with high molecular weight. These additional aqueous phase processes enhance the SOA formation rate in particles and yield two to three orders of magnitude more SOA than predicted based on reaction schemes for dilute aqueous phase (cloud) chemistry for the same conditions (liquid water content, particle size). The application of the new module including detailed chemical processes in a box model demonstrates that both the time scale to reach aqueous phase equilibria and the choice of rate constants of irreversible reactions have a pronounced effect on the predicted atmospheric relevance of SOA formation from glyoxal. During day time, a photochemical (most likely radical-initiated) process is the major SOA formation pathway forming ∼5 μg m-3 SOA over 12 h (assuming a constant glyoxal mixing ratio of 300 ppt). During night time, reactions of nitrogen-containing compounds (ammonium, amines, amino acids) contribute most to the predicted SOA mass; however, the absolute predicted SOA masses are reduced by an order of magnitude as compared to day time production. The contribution of the ammonium reaction significantly increases in moderately acidic or neutral particles (5 < pH < 7). Glyoxal uptake into ammonium sulfate seed under dark conditions can be represented with a single reaction parameter keffupt that does not depend on aerosol loading or water content, which indicates a

  10. Houston urban growth and associated aerosol effects on convection

    NASA Astrophysics Data System (ADS)

    Carrio, G. G.; Cotton, W. R.

    2008-12-01

    In this study we investigate the effects of the Houston Metropolitan Area on the characteristics and intensity of convection and precipitation, focusing on events triggered by the sea breeze circulation. For this purpose, we implemented the Town Energy Budget (TEB) urban model into the an improved version of RAMS that considers the explicit activation of CCN (and giant CCN), a bimodal representation of cloud droplets, a bin- emulation approach for droplet collection, ice-particle riming, and sedimentation, and direct radiative effects of aerosols. TEB is now coupled to run in parallel as to maximize the full potential of our computing resources. RAMS@CSU is configured to use four two-way interactive nested model grids with 42-vertical levels and horizontal grid spacings of 45.0, 15.0, 3.75, and 0.75 km centered over Houston. Grid 1 (50 X 50 grid points) and grid 2 (71 X 61 grid points) are used to simulate the synoptic and mesoscale environments, respectively. While Grids 3 and 4 (102 X 102 grid points and 202 X 202 grid points) are used to resolve deep convection as well and the sea breeze circulation . Numerical experiments cover the effects of perturbing both the urban land-use and the aerosol concentrations as well as variations of both. The Landsat Thematic Mapper National Land Cover Data (NLCD) for the Houston area corresponding to the years 2001 and 2006 were used as benchmarks for the experimental design of the land-use sensitivity experiments, including a run with no city and one of a future scenario. We use aerosol observations during the TexAQS/ GoMACCS field campaign for the initial CCN/GCCN sensitivity experiments. As expected, dramatic impact on the intensity of the convection and precipitation result for the selected case (for August 24, 2000). Additional numerical experiments will be performed by only perturbing the land-use input data as well as varying both aerosol concentration and land use. Sensitivity experiments with an older NCLD land

  11. Particle aggregation with simultaneous surface growth

    SciTech Connect

    pablo.mitchell@cal.Berkeley.EDU

    2003-04-29

    Particle aggregation with simultaneous surface growth was modeled using a dynamic Monte Carlo method. The Monte Carlo algorithm begins in the particle inception zone and constructs aggregates via ensemble-averaged collisions between spheres and deposition of gaseous species on the sphere surfaces. Simulations were conducted using four scenarios. The first, referred to as scenario 0, is used as a benchmark and simulates aggregation in the absence of surface growth. Scenario 1 forces all balls to grow at a uniform rate while scenario 2 only permits them to grow once they have collided and stuck to each other. The last one is a test scenario constructed to confirm conclusions drawn from scenarios 0-2. The transition between the coalescent and the fully-developed fractal aggregation regimes is investigated using shape descriptors to quantify particle geometry. They are used to define the transition between the coalescent and fractal growth regimes. The simulations demonstrate that the morphology of aggregating particles is intimately related to both the surface deposition and particle nucleation rates.

  12. High-efficiency particulate air filter test stand and aerosol generator for particle loading studies.

    PubMed

    Arunkumar, R; Hogancamp, Kristina U; Parsons, Michael S; Rogers, Donna M; Norton, Olin P; Nagel, Brian A; Alderman, Steven L; Waggoner, Charles A

    2007-08-01

    This manuscript describes the design, characterization, and operational range of a test stand and high-output aerosol generator developed to evaluate the performance of 30 x 30 x 29 cm(3) nuclear grade high-efficiency particulate air (HEPA) filters under variable, highly controlled conditions. The test stand system is operable at volumetric flow rates ranging from 1.5 to 12 standard m(3)/min. Relative humidity levels are controllable from 5%-90% and the temperature of the aerosol stream is variable from ambient to 150 degrees C. Test aerosols are produced through spray drying source material solutions that are introduced into a heated stainless steel evaporation chamber through an air-atomizing nozzle. Regulation of the particle size distribution of the aerosol challenge is achieved by varying source solution concentrations and through the use of a postgeneration cyclone. The aerosol generation system is unique in that it facilitates the testing of standard HEPA filters at and beyond rated media velocities by consistently providing, into a nominal flow of 7 standard m(3)/min, high mass concentrations (approximately 25 mg/m(3)) of dry aerosol streams having count mean diameters centered near the most penetrating particle size for HEPA filters (120-160 nm). Aerosol streams that have been generated and characterized include those derived from various concentrations of KCl, NaCl, and sucrose solutions. Additionally, a water insoluble aerosol stream in which the solid component is predominantly iron (III) has been produced. Multiple ports are available on the test stand for making simultaneous aerosol measurements upstream and downstream of the test filter. Types of filter performance related studies that can be performed using this test stand system include filter lifetime studies, filtering efficiency testing, media velocity testing, evaluations under high mass loading and high humidity conditions, and determination of the downstream particle size distributions.

  13. High-efficiency particulate air filter test stand and aerosol generator for particle loading studies.

    PubMed

    Arunkumar, R; Hogancamp, Kristina U; Parsons, Michael S; Rogers, Donna M; Norton, Olin P; Nagel, Brian A; Alderman, Steven L; Waggoner, Charles A

    2007-08-01

    This manuscript describes the design, characterization, and operational range of a test stand and high-output aerosol generator developed to evaluate the performance of 30 x 30 x 29 cm(3) nuclear grade high-efficiency particulate air (HEPA) filters under variable, highly controlled conditions. The test stand system is operable at volumetric flow rates ranging from 1.5 to 12 standard m(3)/min. Relative humidity levels are controllable from 5%-90% and the temperature of the aerosol stream is variable from ambient to 150 degrees C. Test aerosols are produced through spray drying source material solutions that are introduced into a heated stainless steel evaporation chamber through an air-atomizing nozzle. Regulation of the particle size distribution of the aerosol challenge is achieved by varying source solution concentrations and through the use of a postgeneration cyclone. The aerosol generation system is unique in that it facilitates the testing of standard HEPA filters at and beyond rated media velocities by consistently providing, into a nominal flow of 7 standard m(3)/min, high mass concentrations (approximately 25 mg/m(3)) of dry aerosol streams having count mean diameters centered near the most penetrating particle size for HEPA filters (120-160 nm). Aerosol streams that have been generated and characterized include those derived from various concentrations of KCl, NaCl, and sucrose solutions. Additionally, a water insoluble aerosol stream in which the solid component is predominantly iron (III) has been produced. Multiple ports are available on the test stand for making simultaneous aerosol measurements upstream and downstream of the test filter. Types of filter performance related studies that can be performed using this test stand system include filter lifetime studies, filtering efficiency testing, media velocity testing, evaluations under high mass loading and high humidity conditions, and determination of the downstream particle size distributions. PMID

  14. High-efficiency particulate air filter test stand and aerosol generator for particle loading studies

    NASA Astrophysics Data System (ADS)

    Arunkumar, R.; Hogancamp, Kristina U.; Parsons, Michael S.; Rogers, Donna M.; Norton, Olin P.; Nagel, Brian A.; Alderman, Steven L.; Waggoner, Charles A.

    2007-08-01

    This manuscript describes the design, characterization, and operational range of a test stand and high-output aerosol generator developed to evaluate the performance of 30×30×29cm3 nuclear grade high-efficiency particulate air (HEPA) filters under variable, highly controlled conditions. The test stand system is operable at volumetric flow rates ranging from 1.5to12standardm3/min. Relative humidity levels are controllable from 5%-90% and the temperature of the aerosol stream is variable from ambient to 150°C. Test aerosols are produced through spray drying source material solutions that are introduced into a heated stainless steel evaporation chamber through an air-atomizing nozzle. Regulation of the particle size distribution of the aerosol challenge is achieved by varying source solution concentrations and through the use of a postgeneration cyclone. The aerosol generation system is unique in that it facilitates the testing of standard HEPA filters at and beyond rated media velocities by consistently providing, into a nominal flow of 7standardm3/min, high mass concentrations (˜25mg/m3) of dry aerosol streams having count mean diameters centered near the most penetrating particle size for HEPA filters (120-160nm). Aerosol streams that have been generated and characterized include those derived from various concentrations of KCl, NaCl, and sucrose solutions. Additionally, a water insoluble aerosol stream in which the solid component is predominantly iron (III) has been produced. Multiple ports are available on the test stand for making simultaneous aerosol measurements upstream and downstream of the test filter. Types of filter performance related studies that can be performed using this test stand system include filter lifetime studies, filtering efficiency testing, media velocity testing, evaluations under high mass loading and high humidity conditions, and determination of the downstream particle size distributions.

  15. LOAC (Light Optical Particle Counter): a new small aerosol counter with particle characterization capabilities for surface and airborne measurements

    NASA Astrophysics Data System (ADS)

    Renard, Jean-Baptiste; Berthet, Gwenael; Jégou, Fabrice; Jeannot, Matthieu; Jourdain, Line; Dulac, François; Mallet, Marc; Dupont, Jean-Charles; Thaury, Claire; Tonnelier, Thierry; Verdier, Nicolas; Charpentier, Patrick

    2013-04-01

    The determination of the size distribution of tropospheric and stratospheric aerosols with conventional optical counters is difficult when different natures of particles are present (droplets, soot, mineral dust, secondary organic or mineral particles...). Also, a light and cheap aerosol counter that can be used at ground, onboard drones or launched under all kinds of atmospheric balloons can be very useful during specific events as volcanic plumes, desert dust transport or local pollution episodes. These goals can be achieved thanks to a new generation of aerosol counter, called LOAC (Light Optical Aerosol Counter). The instrument was developed in the frame of a cooperation between French scientific laboratories (CNRS), the Environnement-SA and MeteoModem companies and the French Space Agency (CNES). LOAC is a small optical particle counter/sizer of ~250 grams, having a low electrical power consumption. The measurements are conducted at two scattering angles. The first one, at 12°, is used to determine the aerosol particle concentrations in 19 size classes within a diameter range of 0.3-100 micrometerers. At such an angle close to forward scattering, the signal is much more intense and the measurements are the least sensitive to the particle nature. The second angle is at 60°, where the scattered light is strongly dependent on the particle refractive index and thus on the nature of the aerosols. The ratio of the measurements at the two angles is used to discriminate between the different types of particles dominating the nature of the aerosol particles in the different size classes. The sensor particularly discriminates wet or liquid particles, soil dust and soot. Since 2011, we have operated LOAC in various environments (Arctic, Mediterranean, urban and peri-urban…) under different kinds of balloons including zero pressure stratospheric, tethered, drifting tropospheric, and meteorological sounding balloons. For the last case, the total weight of the gondola

  16. The Contribution of Trans-Pacific Submicron Aerosols and Local Particle Nucleation Bursts to California's Air Quality as Seen from the Pacific Coast Mountain Range

    NASA Astrophysics Data System (ADS)

    Asher, E. C. C.; Christensen, J. N.; Post, A.; Faloona, I. C.

    2015-12-01

    The long-range transport of dust and anthropogenic aerosols to the Western US has received considerable attention due to the growing disparity between North American and Asian air quality. Using MODIS and space-borne LIDAR measurements some have argued that the transcontinental transport of dust from Asia, Africa, and Europe outweighs that of locally produced combustion aerosols (Yu et al. 2012). This study seeks to compare the aerosol composition, number, and size distribution of locally derived submicron aerosols (including particle nucleation events) vs. long-range transported aerosols observed at a remote mountain site near the Pacific Coast. Toward this aim, rotating drum impactor (RDI) and scanning mobility particle size (SMPS) measurements of size-segregated elemental compositions and size spectra were collected from February to November of 2012 at Chews Ridge (elevation 1450 m) in Monterey County, California. This mountaintop site experiences two main wind modes. The main mode is ohshore-directed winds from the southwest, which are most likely to bring trans-Pacific aerosols to the site; and offshore-directed, northeasterly winds that bring continental aerosols to the site from the interior of California. Elemental ratios (normalized to Al), matrix factorization, and a k-cluster analysis of these data suggest distinct crustal, combustion, and marine sources with considerable seasonal as well as short-term variability. HYSPLIT model back trajectories support the hypothesized sources of these submicron aerosols. Locally, SMPS data reveal consistent nucleation bursts and subsequent growth in the 20-60 nm range during the afternoons. A distinct but weaker diel cycle was observed in the 70 - 100 nm range, corresponding to the smallest RDI impactor stage. Finally, the Pb isotopic composition (206Pb/207Pb and 208Pb/207Pb) of aerosol samples from selected dates will be measured by MC-ICPMS to further identify aerosol origins (e.g. Ewing et al. 2010).

  17. Variability of CCN Activation Behaviour of Aerosol Particles in the Marine Boundary Layer of the Northern and Southern Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Henning, Silvia; Dieckmann, Katrin; Hartmann, Susan; Schäfer, Michael; Wu, Zhijun; Merkel, Maik; Wiedensohler, Alfred; Stratmann, Frank

    2013-04-01

    The variability of cloud condensation nucleus (CCN) activation behaviour and total CCN number concentrations was investigated during three ship cruises. Measurements were performed in a mobile laboratory on the German research vessel FS Polarstern cruising between Cape Town and Bremerhaven (April / May and October / November 2011) as well as between Punta Arenas and Bremerhaven (April / May 2012). CCN size distributions were measured for supersaturations between 0.1% and 0.4% using a Cloud Condensation Nucleus Counter (DMT, USA). Aerosol particle and CCN total number concentrations as well as the hygroscopicity parameter κ (Petters and Kreidenweis, 2007) were determined. Furthermore, size distribution data were collected. The hygroscopicity parameter κ featured a high variability during the cruises, with a median κ-value of 0.52 ± 0.26. The κ-values are depended on air mass origin; and are as expected mainly dominated by marine influences, but also long range transport of aerosol particles was detected. In the Celtic Sea, κ was found to be lower than that of clean marine aerosol particles (0.72 ± 0.24; Pringle et al., 2010) with κ-values ~0.2, possibly influenced by anthropogenic emissions from Europe. Close to the West African coast particle hygroscopicity was found to be influenced by the Saharan dust plume, resulting in low κ-values ~0.25. Petters, M.D. and S.M. Kreidenweis (2007), A single parameter representation of hygroscopic growth and cloud condensation nucleus activity, Atmos. Chem. and Phys., 7, 1961-1971. Pringle, K.J., H. Tost, A. Pozzer, U. Pöschl, and J. Lelieveld (2010), Global distribution of the effective aerosol hygroscopicity parameter for CCN activation, Atmos. Chem. Phys., 10, 5241-5255.

  18. Stratospheric aerosol particle size information in Odin-OSIRIS limb scatter spectra

    NASA Astrophysics Data System (ADS)

    Rieger, L. A.; Bourassa, A. E.; Degenstein, D. A.

    2014-02-01

    The Optical Spectrograph and InfraRed Imaging System (OSIRIS) onboard the Odin satellite has now taken over a decade of limb scatter measurements that have been used to retrieve the version 5 stratospheric aerosol extinction product. This product is retrieved using a representative particle size distribution to calculate scattering cross sections and scattering phase functions for the forward model calculations. In this work the information content of OSIRIS measurements with respect to stratospheric aerosol is systematically examined for the purpose of retrieving particle size information along with the extinction coefficient. The benefit of using measurements at different wavelengths and scattering angles in the retrieval is studied, and it is found that incorporation of the 1530 nm radiance measurement is key for a robust retrieval of particle size information. It is also found that using OSIRIS measurements at the different solar geometries available on the Odin orbit simultaneously provides little additional benefit. Based on these results, an improved aerosol retrieval algorithm is developed that couples the retrieval of aerosol extinction and mode radius of a log-normal particle size distribution. Comparison of these results with coincident measurements from SAGE III shows agreement in retrieved extinction to within approximately 10% over the bulk of the aerosol layer, which is comparable to version 5. The retrieved particle size, when converted to Ångström coefficient, shows good qualitative agreement with SAGE II measurements made at somewhat shorter wavelengths.

  19. [Concentration and Particle Size Distribution of Microbiological Aerosol During Haze Days in Beijing].

    PubMed

    Hu, Ling-fei; Zhang, Ke; Wang, Hong-bao; Li, Na; Wang, Jie; Yang, Wen-hui; Yin, Zhe; Jiao, Zhou-guang; Wen, Zhan-bo; Li, Jin-song

    2015-09-01

    In this study, we evaluated the bacterial, fungal aerosol concentration, and particle size distribution using microbiological aerosol sampler, and analyzed the particles count concentration of PM1.0, PM2.5, PM5.0 and PM10.0 using aerodynamic particle sizer during clear and haze days in Beijing during Jan 8th, 2013 to Feb 4th, 2013. The concentration of bacterial, fungal aerosol, air particulate matter and aerosol distribution were compared between haze days and clear days. Our results indicated that the proportion of fungal particles smaller than 5 micron, which could deposit in lungs or deeper regions, was much higher than bacterial particles. The biological concentration of bacteria and fungi were higher in clear days than in haze days, and there was no statistic difference of the microbiological aerosol distribution. The concentration of air particulate matter were higher in haze days than in clear days, PM10 was the main particulate matters both in clear days and haze days.

  20. Limits of DPUI application associated with the number of particles within actinide aerosols.

    PubMed

    Fritsch, P; Raynaud, P; Blanchin, N; Mièle, A

    2007-01-01

    Dose per unit intake (DPUI) of radionuclides is obtained using International Commission on Radiological Protection (ICRP) models. After inhalation exposure, the first model calculates the fraction of activity deposited within the different regions of the respiratory tract, assuming that the aerosol contains an infinite number of particles. Using default parameters for workers, an exposure to one annual limit of intake (ALI) corresponds to an aerosol of 239PuO2 containing approximately 1 x 10(6) particles. To reach such an exposure, very low particle number might be involved especially for compounds having a high specific activity. This study provides examples of exposures to actinide aerosols for which the number of particles is too low for a standard application of the ICRP model. These examples, which involve physical studies of aerosols collected at the workplace and interpretation of bioassay data, show that the number of particles of the aerosol can be the main limit for the application of DPUI after inhalation exposure.

  1. Characterization of aerosol particles from grass mowing by joint deployment of ToF-AMS and ATOFMS instruments

    NASA Astrophysics Data System (ADS)

    Drewnick, Frank; Dall'Osto, Manuel; Harrison, Roy

    During a measurement campaign at a semi-urban/industrial site a grass-cutting event was observed, when the lawn in the immediate surrounding of the measurement site was mowed. Using a wide variety of state-of-the-art aerosol measurement technology allowed a broad characterization of the aerosol generated by the lawn mowing. The instrumentation included two on-line aerosol mass spectrometers: an Aerodyne Time-of-Flight Aerosol Mass Spectrometer (ToF-AMS) and a TSI Aerosol Time-of-Flight Mass Spectrometer (ATOFMS); in addition, a selection of on-line aerosol concentration and size distribution instruments (OPC, APS, SMPS, CPC, FDMS-TEOM, MAAP) was deployed. From comparison of background aerosol measurements during most of the day with the aerosol measured during the lawn mowing, the grass cutting was found to generate mainly two different types of aerosol particles: an intense ultrafine particle mode (1 h average: 4 μg m -3) of almost pure hydrocarbon-like organics and a distinct particle mode in the upper sub-micrometer size range containing particles with potassium and nitrogen-organic compounds. The ultrafine particles are probably lubricating oil particles from the lawn mower exhaust; the larger particles are swirled-up plant debris particles from the mowing process. While these particle types were identified in the data from the two mass spectrometers, the on-line aerosol concentration and size distribution data support these findings. The results presented here show that the combination of quantitative aerosol particle ensemble mass spectrometry (ToF-AMS) and single particle mass spectrometry (ATOFMS) provides much deeper insights into the nature of the aerosol properties than each of the instruments could do alone. Therefore a combined deployment of both types of instruments is strongly recommended.

  2. Chemometric analysis of multi-sensor hyperspectral images of coarse mode aerosol particles for the image-based investigation on aerosol particles

    NASA Astrophysics Data System (ADS)

    Ofner, Johannes; Kamilli, Katharina A.; Eitenberger, Elisabeth; Friedbacher, Gernot; Lendl, Bernhard; Held, Andreas; Lohninger, Hans

    2015-04-01

    Multi-sensor hyperspectral imaging is a novel technique, which allows the determination of composition, chemical structure and pure components of laterally resolved samples by chemometric analysis of different hyperspectral datasets. These hyperspectral datasets are obtained by different imaging methods, analysing the same sample spot and superimposing the hyperspectral data to create a single multi-sensor dataset. Within this study, scanning electron microscopy (SEM), Raman and energy-dispersive X-ray spectroscopy (EDX) images were obtained from size-segregated aerosol particles, sampled above Western Australian salt lakes. The particles were collected on aluminum foils inside a 2350 L Teflon chamber using a Sioutas impactor, sampling aerosol particles of sizes between 250 nm and 10 µm. The complex composition of the coarse-mode particles can be linked to primary emissions of inorganic species as well as to oxidized volatile organic carbon (VOC) emissions. The oxidation products of VOC emissions are supposed to form an ultra-fine nucleation mode, which was observed during several field campaigns between 2006 and 2013. The aluminum foils were analysed using chemical imaging and electron microscopy. A Horiba LabRam 800HR Raman microscope was used for vibrational mapping of an area of about 100 µm x 100 µm of the foils at a resolution of about 1 µm. The same area was analysed using a Quanta FEI 200 electron microscope (about 250 nm resolution). In addition to the high-resolution image, the elemental composition could be investigated using energy-dispersive X-ray spectroscopy. The obtained hyperspectral images were combined into a multi-sensor dataset using the software package Imagelab (Epina Software Labs, www.imagelab.at). After pre-processing of the images, the multi-sensor hyperspectral dataset was analysed using several chemometric methods such as principal component analysis (PCA), hierarchical cluster analysis (HCA) and other multivariate methods. Vertex

  3. TEM Study of Aerosol Particles in Brown Haze Episodes over Northern China in Spring 2007

    NASA Astrophysics Data System (ADS)

    Li, W.; Shao, L.; Buseck, P. R.

    2008-12-01

    Airborne aerosol collections were performed in eight brown haze episodes from 31 May to 21 June 2007 in Beijing, China. Morphologies, compositions, and mixing states of individual aerosol particles having different sizes were obtained using transmission electron microscopy (TEM). Aerosol particle types less than 2 μ m in diameter include mineral dust, fly ash, soot, organic material, and K-rich, S-rich, and metal particles (Fe- and Zn-rich). Mineral dust particles dominate in the range of 2 to 10 μ m. In addition to finding contributions from vehicle emissions and soil dust in Beijing, TEM results from the study provide new insights into sources such as agricultural biomass burning, industrial activities, and waste incineration. These sources can contribute not only great amounts of K-rich and metal particles but also reactive gases such as NH3, NOx, SO2, and VOCs to the haze. More than 80% of the analyzed aerosol particles are internally mixed. K- and S-rich particles tend to be coagulated with fly ash, soot, metal, and fine-grained mineral dust particles. Organic materials can act as inclusions in the K- and S-rich particles and their coatings. Over 90% of the analyzed internally mixed mineral particles are covered with Ca-, Mg-, or Na-rich coatings, and only 8% are associated with K- or S-rich coatings. The compositions of Ca-, Mg-, and Na-rich coatings suggest that they are possibly nitrates mixed with minor sulfates and chlorides. Calcium sulfate particles with diameters from 10 to 500 nm were also detected within Ca(NO3)2 and Mg(NO3)2 coatings. These results indicate that mineral dust particles in the brown haze episodes participated in heterogeneous reactions in the atmosphere with one or more of SO2, NO2, HCl, and HNO3. The development of coatings altered some mineral dust particles from hydrophobic to hydrophilic.

  4. Simulating the Evolution of Soot Mixing State with a Particle-Resolved Aerosol Model

    SciTech Connect

    Riemer, Nicole; West, Matt; Zaveri, Rahul A.; Easter, Richard C.

    2009-05-05

    The mixing state of soot particles in the atmosphere is of crucial importance for assessing their climatic impact, since it governs their chemical reactivity, cloud condensation nuclei activity and radiative properties. To improve the mixing state representation in models, we present a new approach, the stochastic particle-resolved model PartMC-MOSAIC, which explicitly resolves the composition of individual particles in a given population of different types of aerosol particles. This approach accurately tracks the evolution of the mixing state of particles due to emission, dilution, condensation and coagulation. To make this direct stochastic particle-based method practical, we implemented a new multiscale stochastic coagulation method. With this method we achieved optimal efficiency for applications when the coagulation kernel is highly non-uniform, as is the case for many realistic applications. PartMC-MOSAIC was applied to an idealized urban plume case representative of a large urban area to simulate the evolution of carbonaceous aerosols of different types due to coagulation and condensation. For this urban plume scenario we quantified the individual processes that contribute to the aging of the aerosol distribution, illustrating the capabilities of our modeling approach. The results showed for the first time the multidimensional structure of particle composition, which is usually lost in internally-mixed sectional or modal aerosol models.

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

    NASA Astrophysics Data System (ADS)

    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.

  6. Two-dimensional Guinier analysis: application to single aerosol particles in-flight.

    PubMed

    Berg, Matthew J; Hill, Steve C; Pan, Yong-Le; Videen, Gorden

    2010-10-25

    This work presents an apparatus that measures near-forward two-dimensional elastic scattering patterns of single aerosol particles and proposes a two-angle extension of the Guinier law to analyze these patterns. The particles, which approximately range from 2 to 8 micrometers in size, flow through the apparatus in an aerosol stream. A spatial filtering technique separates the near-forward portion of the patterns from the illumination light. Contours intended to represent the geometrical profile of the particles are generated from the patterns using the extension of the Guinier law. The analysis is applied to spherical and nonspherical particles, and the resulting contours are found to be consistent with particle shape only for spherical particles.

  7. Retrievals of Aerosol and Cloud Particle Microphysics Using Polarization and Depolarization Techniques

    NASA Technical Reports Server (NTRS)

    Mishchenko, Michael; Hansen, James E. (Technical Monitor)

    2001-01-01

    The recent availability of theoretical techniques for computing single and multiple scattering of light by realistic polydispersions of spherical and nonspherical particles and the strong dependence of the Stokes scattering matrix on particle size, shape, and refractive index make polarization and depolarization measurements a powerful particle characterization tool. In this presentation I will describe recent applications of photopolarimetric and lidar depolarization measurements to remote sensing characterization of tropospheric aerosols, polar stratospheric clouds (PSCs), and contrails. The talk will include (1) a short theoretical overview of the effects of particle microphysics on particle single-scattering characteristics; (2) the use of multi-angle multi-spectral photopolarimetry to retrieve the optical thickness, size distribution, refractive index, and number concentration of tropospheric aerosols over the ocean surface; and (3) the application of the T-matrix method to constraining the PSC and contrail particle microphysics using multi-spectral measurements of lidar backscatter and depolarization.

  8. Influence of crustal dust and sea spray supermicron particle concentrations and acidity on inorganic NO3- aerosol during the 2013 Southern Oxidant and Aerosol Study

    SciTech Connect

    Allen, Hannah M.; Draper, Danielle C.; Ayres, Benjamin R.; Ault, Andrew P.; Bondy, Amy L.; Takahama, S.; Modini, Robert; Baumann, K.; Edgerton, Eric S.; Knote, Christoph; Laskin, Alexander; Wang, Bingbing; Fry, Juliane L.

    2015-09-25

    The inorganic aerosol composition was measured in the southeastern United States, a region that exhibits high aerosol mass loading during the summer, as part of the 1 June to 15 July 2013 Southern Oxidant and Aerosol Study (SOAS) campaign. Measurements using a Monitor for AeRosols and GAses (MARGA), an ion chromatograph coupled with a wet rotating denuder and a steam-jet aerosol collector for monitoring of ambient inorganic gas and aerosol species, revealed two periods of high aerosol nitrate (NO3 ) concentrations during the campaign. These periods of high nitrate were correlated with increased concentrations of coarse mode mineral or sea spray aerosol species, particularly Na+ and Ca2+, and with a shift towards aerosol with larger (1 to 2.5 um) diameters. We suggest this nitrate aerosol forms by multiphase reactions of HNO3 and particles, reactions that are facilitated by transport of mineral dust and sea spray aerosol from a source within the United States. The observed high aerosol acidity prevents the formation of NH4NO3, the inorganic nitrogen species often dominant in fine-mode aerosol at higher pH. Calculation of the rate of the heterogeneous uptake of HNO3 on mineral aerosol supports the conclusion that aerosol NO3 is produced primarily by this process, and is likely limited by the availability of mineral dust surface area. Modeling of NO3 and HNO3 by thermodynamic equilibrium models (ISORROPIA II and E-AIM) reveals the importance of including mineral cations in the southeastern United States to accurately balance ion species and predict gas/aerosol phase partitioning.

  9. Relating the hygroscopic properties of submicron aerosol to both gas- and particle-phase chemical composition in a boreal forest environment

    NASA Astrophysics Data System (ADS)

    Hong, J.; Kim, J.; Nieminen, T.; Duplissy, J.; Ehn, M.; Äijälä, M.; Hao, L. Q.; Nie, W.; Sarnela, N.; Prisle, N. L.; Kulmala, M.; Virtanen, A.; Petäjä, T.; Kerminen, V.-M.

    2015-10-01

    Measurements of the hygroscopicity of 15-145 nm particles in a boreal forest environment were conducted using two Hygroscopicity Tandem Differential Mobility Analyzer (HTDMA) systems during the Pan-European Gas-Aerosols-climate interaction Study (PEGASOS) campaign in spring 2013. Measurements of the chemical composition of non-size segregated particles were also performed using a high-resolution aerosol mass spectrometer (HR-AMS) in parallel with hygroscopicity measurements. On average, the hygroscopic growth factor (HGF) of particles was observed to increase from the morning until afternoon. In case of accumulation mode particles, the main reasons for this behavior were increases in the ratio of sulfate to organic matter and oxidation level (O : C ratio) of the organic matter in the particle phase. Using an O : C dependent hygroscopic growth factor of organic matter (HGForg), fitted using the inverse Zdanovskii-Stokes-Robinson (ZSR) mixing rule, clearly improved the agreement between measured HGF and that predicted based on HR-AMS composition data. Besides organic oxidation level, the influence of inorganic species was tested when using the ZSR mixing rule to estimate the hygroscopic growth factor of organics in the aerosols. While accumulation and Aitken mode particles were predicted fairly well by the bulk aerosol composition data, the hygroscopicity of nucleation mode particles showed little correlation. However, we observed them to be more sensitive to the gas phase concentration of condensable vapors: the more sulfuric acid in the gas phase, the more hygroscopic the nucleation mode particles were. No clear dependence was found between the extremely low-volatility organics concentration (ELVOC) and the HGF of particles of any size.

  10. Evaluation and Modification of Commercial Dry Powder Inhalers for the Aerosolization of a Submicrometer Excipient Enhanced Growth (EEG) Formulation

    PubMed Central

    Son, Yoen-Ju; Longest, P. Worth; Tian, Geng; Hindle, Michael

    2013-01-01

    The aim of this study was to evaluate and modify commercial dry powder inhalers (DPIs) for the aerosolization of a submicrometer excipient enhanced growth (EEG) formulation. The optimized device and formulation combination was then tested in a realistic in vitro mouth-throat - tracheobronchial (MT-TB) model. An optimized EEG submicrometer powder formulation, consisting of albuterol sulfate (drug), mannitol (hygroscopic excipient), L-leucine (dispersion enhancer) and poloxamer 188 (surfactant) in a ratio of 30:48:20:2 was prepared using a Büchi Nano spray dryer. The aerosolization performance of the EEG formulation was evaluated with 5 conventional DPIs: Aerolizer, Novolizer, HandiHaler, Exubera and Spiros. To improve powder dispersion, the HandiHaler was modified with novel mouth piece (MP) designs. The aerosol performance of each device was assessed using a next generation impactor (NGI) at airflow rates generating a pressure drop of 4 kPa across the DPI. In silico and in vitro deposition and hygroscopic growth of formulations was studied using a MT-TB airway geometry model. Both Handihaler and Aerolizer produced high emitted doses (ED) together with a significant submicrometer aerosol fraction. A modified HandiHaler with a MP including a three-dimensional (3D) array of rods (HH-3D) produced a submicrometer particle fraction of 38.8% with a conventional fine particle fraction (% <5µm) of 97.3%. The mass median diameter (MMD) of the aerosol was reduced below 1 µm using this HH-3D DPI. The aerosol generated from the modified HandiHaler increased to micrometer size (2.8 µm) suitable for pulmonary deposition, when exposed to simulated respiratory conditions, with negligible mouth-throat (MT) deposition (2.6 %). PMID:23608613

  11. Modelling non-equilibrium secondary organic aerosol formation and evaporation with the aerosol dynamics, gas- and particle-phase chemistry kinetic multilayer model ADCHAM

    NASA Astrophysics Data System (ADS)

    Roldin, P.; Eriksson, A. C.; Nordin, E. Z.; Hermansson, E.; Mogensen, D.; Rusanen, A.; Boy, M.; Swietlicki, E.; Svenningsson, B.; Zelenyuk, A.; Pagels, J.

    2014-08-01

    We have developed the novel Aerosol Dynamics, gas- and particle-phase chemistry model for laboratory CHAMber studies (ADCHAM). The model combines the detailed gas-phase Master Chemical Mechanism version 3.2 (MCMv3.2), an aerosol dynamics and particle-phase chemistry module (which considers acid-catalysed oligomerization, heterogeneous oxidation reactions in the particle phase and non-ideal interactions between organic compounds, water and inorganic ions) and a kinetic multilayer module for diffusion-limited transport of compounds between the gas phase, particle surface and particle bulk phase. In this article we describe and use ADCHAM to study (1) the evaporation of liquid dioctyl phthalate (DOP) particles, (2) the slow and almost particle-size-independent evaporation of α-pinene ozonolysis secondary organic aerosol (SOA) particles, (3) the mass-transfer-limited uptake of ammonia (NH3) and formation of organic salts between ammonium (NH4+) and carboxylic acids (RCOOH), and (4) the influence of chamber wall effects on the observed SOA formation in smog chambers. ADCHAM is able to capture the observed α-pinene SOA mass increase in the presence of NH3(g). Organic salts of ammonium and carboxylic acids predominantly form during the early stage of SOA formation. In the smog chamber experiments, these salts contribute substantially to the initial growth of the homogeneously nucleated particles. The model simulations of evaporating α-pinene SOA particles support the recent experimental findings that these particles have a semi-solid tar-like amorphous-phase state. ADCHAM is able to reproduce the main features of the observed slow evaporation rates if the concentration of low-volatility and viscous oligomerized SOA material at the particle surface increases upon evaporation. The evaporation rate is mainly governed by the reversible decomposition of oligomers back to monomers. Finally, we demonstrate that the mass-transfer-limited uptake of condensable organic compounds

  12. Spontaneous Aerosol Ejection: Origin of Inorganic Particles in Biomass Pyrolysis.

    PubMed

    Teixeira, Andrew R; Gantt, Rachel; Joseph, Kristeen E; Maduskar, Saurabh; Paulsen, Alex D; Krumm, Christoph; Zhu, Cheng; Dauenhauer, Paul J

    2016-06-01

    At high thermal flux and temperatures of approximately 500 °C, lignocellulosic biomass transforms to a reactive liquid intermediate before evaporating to condensable bio-oil for downstream upgrading to renewable fuels and chemicals. However, the existence of a fraction of nonvolatile compounds in condensed bio-oil diminishes the product quality and, in the case of inorganic materials, catalyzes undesirable aging reactions within bio-oil. In this study, ablative pyrolysis of crystalline cellulose was evaluated, with and without doped calcium, for the generation of inorganic-transporting aerosols by reactive boiling ejection from liquid intermediate cellulose. Aerosols were characterized by laser diffraction light scattering, inductively coupled plasma spectroscopy, and high-speed photography. Pyrolysis product fractionation revealed that approximately 3 % of the initial feed (both organic and inorganic) was transported to the gas phase as aerosols. Large bubble-to-aerosol size ratios and visualization of significant late-time ejections in the pyrolyzing cellulose suggest the formation of film bubbles in addition to the previously discovered jet formation mechanism.

  13. Water uptake by organic aerosol and its influence on gas/particle partitioning of secondary organic aerosol in the United States

    NASA Astrophysics Data System (ADS)

    Jathar, Shantanu H.; Mahmud, Abdullah; Barsanti, Kelley C.; Asher, William E.; Pankow, James F.; Kleeman, Michael J.

    2016-03-01

    Organic aerosol (OA) is at least partly hygroscopic, i.e., water partitions into the organic phase to a degree determined by the relative humidity (RH), the organic chemical composition, and the particle size. This organic-phase water increases the aerosol mass and provides a larger absorbing matrix while decreasing its mean molecular weight, which can encourage additional condensation of semi-volatile organic compounds. Most regional and global atmospheric models account for water uptake by inorganic salts but do not explicitly account for organic-phase water and its subsequent impact on gas/particle partitioning of semi-volatile OA. In this work, we incorporated the organic-phase water model described by Pankow et al. (2015) into the UCD/CIT air quality model to simulate water uptake by OA and assessed its influence on total OA mass concentrations. The model was run for one summer month over two distinct regions: South Coast Air Basin (SoCAB) surrounding Los Angeles, California and the eastern United States (US). In SoCAB where the OA was dominated by non-hygroscopic primary OA (POA), there was very little organic-phase water uptake (0.1-0.2 μg m-3) and consequently very little enhancement (or growth) in total OA concentrations (OA + organic-phase water): a 3% increase in total OA mass was predicted for a 0.1 increase in relative humidity. In contrast, in the eastern US where secondary OA (SOA) from biogenic sources dominated the OA, substantial organic-phase water uptake and enhancement in total OA concentrations was predicted, even in urban locations. On average, the model predicted a 20% growth in total OA mass for a 0.1 increase in relative humidity; the growth was equivalent to a 250 nm particle with a hygroscopicity parameter (κ) of 0.15. Further, for the same relative humidity, the exact extent of organic-phase water uptake and total OA enhancement was found to be dependent on the particle mixing state. When the source-oriented mixing state of aerosols

  14. Light scattering and absorption properties of aerosol particles in the urban environment of Granada, Spain

    NASA Astrophysics Data System (ADS)

    Lyamani, H.; Olmo, F. J.; Alados-Arboledas, L.

    Surface measurements of optical and physical aerosol properties were made at an urban site, Granada (Spain) (37.18°N, 3.58°W, 680 m a.s.l), during winter 2005-2006. Measurements included the aerosol scattering, σsca, and backscattering coefficients, σbsca, at three wavelengths (450, 550 and 700 nm) measured at low relative humidity (RH<50%) by an integrating nephelometer, the absorption coefficient at 670 nm, σabs, measured with a multi-angle absorption photometer, and aerosol size distribution in the 0.5-20 μm aerodynamic diameter range registered by an aerodynamic aerosol sizer (APS-3321, TSI). The hourly average of σsca (550 nm) ranged from 2 to 424 M m -1 with an average value of 84±62 M m -1 (±S.D.). The Angstrom exponent presented an average value of 1.8±0.3, suggesting a large fraction of fine particles at the site, an observation confirmed by aerosol size distribution measurements. The hourly average of σabs (670 nm) ranged from 1.7 to 120.5 M m -1 with an average value of 28±20 M m -1. The results indicate that the aerosol absorption coefficient in Granada was relatively large. The largest σsca value was associated with air masses that passed over heavily polluted European areas and local stagnation conditions. High absorbing aerosol level was obtained during dust transport from North Africa probably due to the presence of hematite. Based on the measured scattering and absorption coefficients, a very low average value of the single scattering albedo of 0.66±0.11 at 670 nm was calculated, suggesting that urban aerosols in this region contain a large fraction of absorbing material. A clear diurnal pattern was observed in scattering and absorption coefficients and particle concentrations with two local maxima occurring in early morning and late evening. This behavior can be explained in terms of local conditions that control the particle sources associated with traffic and upward mixing of the aerosol during the daytime development of a

  15. Enhanced High-Temperature Ice Nucleation Ability of Crystallized Aerosol Particles after Pre-Activation at Low Temperature

    NASA Astrophysics Data System (ADS)

    Wagner, R.; Moehler, O.; Saathoff, H.; Schnaiter, M.

    2014-12-01

    The term pre-activation in heterogeneous ice nucleation describes the observation that the ice nucleation ability of solid ice nuclei may improve after they have already been involved in ice crystal formation or have been exposed to a temperature lower than 235 K. This can be explained by the retention of small ice embryos in cavities or crevices at the particle surface or by the capillary condensation and freezing of supercooled water, respectively. In recent cloud chamber experiments with crystallized aqueous ammonium sulfate, oxalic acid, and succinic acid solution droplets, we have unraveled a further pre-activation mechanism under ice subsaturated conditions which does not require the preceding growth of ice on the seed aerosol particles (Wagner, R. et al., J. Geophys. Res. Atmos., 119, doi: 10.1002/2014JD021741). First cloud expansion experiments were performed at a high temperature (267 - 244 K) where the crystallized particles did not promote any heterogeneous ice nucleation. Ice nucleation at this temperature, however, could be triggered by temporarily cooling the crystallized particles to a lower temperature. This is because upon crystallization, residuals of the aqueous solution are trapped within the crystals. These captured liquids can freeze when cooled below their respective homogeneous or heterogeneous freezing temperature, leading to the formation of ice pockets in the crystalline particles. When warmed again to the higher temperature, ice formation by the pre-activated particles occurred via depositional and deliquescence-induced ice growth, with ice active fractions ranging from 1 to 4% and 4 to 20%, respectively. Pre-activation disappeared above the eutectic temperature, which for the organic acids are close to the melting point of ice. This mechanism could therefore contribute to the very small fraction of atmospheric aerosol particles that are still ice active well above 263 K.

  16. Ice cloud processing of ultra-viscous/glassy aerosol particles leads to enhanced ice nucleation ability

    NASA Astrophysics Data System (ADS)

    Wagner, R.; Möhler, O.; Saathoff, H.; Schnaiter, M.; Skrotzki, J.; Leisner, T.; Wilson, T. W.; Malkin, T. L.; Murray, B. J.

    2012-09-01

    The ice nucleation potential of airborne glassy aqueous aerosol particles has been investigated by controlled expansion cooling cycles in the AIDA aerosol and cloud chamber of the Karlsruhe Institute of Technology at temperatures between 247 and 216 K. Four different solutes were used as proxies for oxygenated organic matter found in the atmosphere: raffinose, 4-hydroxy-3-methoxy-DL-mandelic acid (HMMA), levoglucosan, and a multi-component mixture of raffinose with five dicarboxylic acids and ammonium sulphate. Similar to previous experiments with citric acid aerosols, all particles were found to nucleate ice heterogeneously before reaching the homogeneous freezing threshold provided that the freezing cycles were started well below the respective glass transition temperatures of the compounds; this is discussed in detail in a separate article. In this contribution, we identify a further mechanism by which glassy aerosols can promote ice nucleation below the homogeneous freezing limit. If the glassy aerosol particles are probed in freezing cycles started only a few degrees below their respective glass transition temperatures, they enter the liquid regime of the state diagram upon increasing relative humidity (moisture-induced glass-to-liquid transition) before being able to act as heterogeneous ice nuclei. Ice formation then only occurs by homogeneous freezing at elevated supersaturation levels. When ice forms the remaining solution freeze concentrates and re-vitrifies. If these ice cloud processed glassy aerosol particles are then probed in a second freezing cycle at the same temperature, they catalyse ice formation at a supersaturation threshold between 5 and 30% with respect to ice. By analogy with the enhanced ice nucleation ability of insoluble ice nuclei like mineral dusts after they nucleate ice once, we refer to this phenomenon as pre-activation. We propose a number of possible explanations for why glassy aerosol particles that have re-vitrified in contact

  17. Mass Analysis of Charged Aerosol Particles During the MASS/ECOMA Campaign

    NASA Astrophysics Data System (ADS)

    Knappmiller, S.; Robertson, S.; Horanyi, M.; Sternovsky, Z.

    2008-12-01

    . The Mesospheric Aerosol Sampling Spectrometer (MASS) instrument was launched on two sounding rockets in August 2007 from Andoya, Norway to find the masses of charged aerosol particles in the polar mesosphere in NLC/PMSE conditions (3 August) and PMSE conditions alone (6 August). We compare and contrast the four data sets from the uplegs and downlegs. The MASS instrument collected ions, cluster ions, and charged nanometer-sized particles on four pairs of electrically-biased graphite plates that collect positive and negative particles separately. Electron collection was prevented by the negative potential on the rocket body. For the 3 August upleg, the data show charged particle collection on all channels with number densities of order several thousand per cubic centimeter in the four size ranges < 0.5 nm, 0.5-1 nm, 1-2 nm, and > 3 nm. The occurrence of positively charged aerosol particles in the smallest sizes suggests positive ions as the nucleation sites because the smallest particles have negligible probability of charging by photoionization. The signals were smaller on the 3 August downleg as a consequence of the spatial variability of the cloud. For the 6 August upleg into PMSE alone, only smaller particles (< 2 nm) were detected and these were both positive and negative with number densities of several thousand per cubic centimeter. On the downleg, 1-2 nm negatively charged particles were detected, but there were no positive particles in this mass range.

  18. Thermal desorption single particle mass spectrometry of ambient aerosol in Shanghai

    NASA Astrophysics Data System (ADS)

    Zhai, Jinghao; Wang, Xinning; Li, Jingyan; Xu, Tingting; Chen, Hong; Yang, Xin; Chen, Jianmin

    2015-12-01

    Submicron aerosol volatility, chemical composition, and mixing state were simultaneously measured using a thermodenuder (TD) in-line with a single particle aerosol mass spectrometry (SPAMS) during Nov.12 to Dec. 11 of 2014 in Shanghai. By heating up to 250 °C, the signals of refractory species such as elemental carbon, metallic compounds, and mineral dust in aerosols were enhanced in the mass spectra. At 250 °C, the main particle types present in the size range of 0.2-1.0 μm were biomass burning (37% by number) and elemental carbon (20%). From 1.0 to 2.0 μm, biomass burning (30%), dust (19%) and metal-rich (18%) were the primary particle types. CN- signal remained in the mass spectra of the heated biomass burning particles suggests the existence of some extremely low-volatility nitrogen-containing organics. Laboratory experiments were conducted by burning rice straws, the main source material of biomass burning particles in Southern China, to confirm the less volatile composition contributed by biomass burning. Strong CN- with relative area >0.21 was observed in most of the laboratory-made biomass burning particles when heated above 200 °C and was selected as a new marker to identify the biomass burning particles in the field. The TD-SPAMS measured the size-resolved chemical composition of the individual particle residues at different temperatures and offered more information on the aging processes of primary particles and their sources.

  19. Aerosol and Cloud-Nucleating Particle Observations during an Atmospheric River Event

    NASA Astrophysics Data System (ADS)

    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

  20. Individual Aerosol Particles from Biomass Burning in Southern Africa. 1; Compositions and Size Distributions of Carbonaceous Particles

    NASA Technical Reports Server (NTRS)

    Posfai, Mihaly; Simonics, Renata; Li, Jia; Hobbs, Peter V.; Buseck, Peter R.

    2003-01-01

    Individual aerosol particles in smoke plumes from biomass fires and in regional hazes in southern Africa were studied using analytical transmission electron microscopy (TEM), which allowed detailed characterization of carbonaceous particle types in smoke and determination of changes in particle properties and concentrations during smoke aging. Based on composition, morphology, and microstructure, three distinct types of carbonaceous particles were present in the smoke: organic particles with inorganic (K-salt) inclusions, tar ball particles, and soot. The relative number concentrations of organic particles were largest in young smoke, whereas tar balls were dominant in a slightly aged (1 hour) smoke from a smoldering fire. Flaming fires emitted relatively more soot particles than smoldering fires, but soot was a minor constituent of all studied plumes. Further aging caused the accumulation of sulfate on organic and soot particles, as indicated by the large number of internally mixed organic/sulfate and soot/sulfate particles in the regional haze. Externally mixed ammonium sulfate particles dominated in the boundary layer hazes, whereas organic/sulfate particles were the most abundant type in the upper hazes. Apparently, elevated haze layers were more strongly affected by biomass smoke than those within the boundary layer. Based on size distributions and the observed patterns of internal mixing, we hypothesize that organic and soot particles are the cloud-nucleating constituents of biomass smoke aerosols. Sea-salt particles dominated in the samples taken in stratus clouds over the Atlantic Ocean, off the coast of Namibia, whereas a distinct haze layer above the clouds consisted of aged biomass smoke particles.

  1. Penetration of Combustion Aerosol Particles Through Filters of NIOSH-Certified Filtering Facepiece Respirators (FFRs).

    PubMed

    Gao, Shuang; Kim, Jinyong; Yermakov, Michael; Elmashae, Yousef; He, Xinjian; Reponen, Tiina; Grinshpun, Sergey A

    2015-01-01

    Filtering facepiece respirators (FFRs) are commonly worn by first responders, first receivers, and other exposed groups to protect against exposure to airborne particles, including those originated by combustion. Most of these FFRs are NIOSH-certified (e.g., N95-type) based on the performance testing of their filters against charge-equilibrated aerosol challenges, e.g., NaCl. However, it has not been examined if the filtration data obtained with the NaCl-challenged FFR filters adequately represent the protection against real aerosol hazards such as combustion particles. A filter sample of N95 FFR mounted on a specially designed holder was challenged with NaCl particles and three combustion aerosols generated in a test chamber by burning wood, paper, and plastic. The concentrations upstream (Cup) and downstream (Cdown) of the filter were measured with a TSI P-Trak condensation particle counter and a Grimm Nanocheck particle spectrometer. Penetration was determined as (Cdown/Cup) ×100%. Four test conditions were chosen to represent inhalation flows of 15, 30, 55, and 85 L/min. Results showed that the penetration values of combustion particles were significantly higher than those of the "model" NaCl particles (p < 0.05), raising a concern about applicability of the N95 filters performance obtained with the NaCl aerosol challenge to protection against combustion particles. Aerosol type, inhalation flow rate and particle size were significant (p < 0.05) factors affecting the performance of the N95 FFR filter. In contrast to N95 filters, the penetration of combustion particles through R95 and P95 FFR filters (were tested in addition to N95) were not significantly higher than that obtained with NaCl particles. The findings were attributed to several effects, including the degradation of an N95 filter due to hydrophobic organic components generated into the air by combustion. Their interaction with fibers is anticipated to be similar to those involving "oily" particles

  2. Penetration of Combustion Aerosol Particles Through Filters of NIOSH-Certified Filtering Facepiece Respirators (FFRs).

    PubMed

    Gao, Shuang; Kim, Jinyong; Yermakov, Michael; Elmashae, Yousef; He, Xinjian; Reponen, Tiina; Grinshpun, Sergey A

    2015-01-01

    Filtering facepiece respirators (FFRs) are commonly worn by first responders, first receivers, and other exposed groups to protect against exposure to airborne particles, including those originated by combustion. Most of these FFRs are NIOSH-certified (e.g., N95-type) based on the performance testing of their filters against charge-equilibrated aerosol challenges, e.g., NaCl. However, it has not been examined if the filtration data obtained with the NaCl-challenged FFR filters adequately represent the protection against real aerosol hazards such as combustion particles. A filter sample of N95 FFR mounted on a specially designed holder was challenged with NaCl particles and three combustion aerosols generated in a test chamber by burning wood, paper, and plastic. The concentrations upstream (Cup) and downstream (Cdown) of the filter were measured with a TSI P-Trak condensation particle counter and a Grimm Nanocheck particle spectrometer. Penetration was determined as (Cdown/Cup) ×100%. Four test conditions were chosen to represent inhalation flows of 15, 30, 55, and 85 L/min. Results showed that the penetration values of combustion particles were significantly higher than those of the "model" NaCl particles (p < 0.05), raising a concern about applicability of the N95 filters performance obtained with the NaCl aerosol challenge to protection against combustion particles. Aerosol type, inhalation flow rate and particle size were significant (p < 0.05) factors affecting the performance of the N95 FFR filter. In contrast to N95 filters, the penetration of combustion particles through R95 and P95 FFR filters (were tested in addition to N95) were not significantly higher than that obtained with NaCl particles. The findings were attributed to several effects, including the degradation of an N95 filter due to hydrophobic organic components generated into the air by combustion. Their interaction with fibers is anticipated to be similar to those involving "oily" particles

  3. Modelling non-equilibrium secondary organic aerosol formation and evaporation with the aerosol dynamics, gas- and particle-phase chemistry kinetic multilayer model ADCHAM

    SciTech Connect

    Roldin, P.; Eriksson, A. C.; Nordin, E. Z.; Hermansson, E.; Mogensen, Ditte; Rusanen, A.; Boy, Michael; Swietlicki, E.; Svenningsson, Birgitta; Zelenyuk, Alla; Pagels, J.

    2014-08-11

    We have developed the novel Aerosol Dynamics, gas- and particle- phase chemistry model for laboratory CHAMber studies (ADCHAM). The model combines the detailed gas phase Master Chemical Mechanism version 3.2, an aerosol dynamics and particle phase chemistry module (which considers acid catalysed oligomerization, heterogeneous oxidation reactions in the particle phase and non-ideal interactions between organic compounds, water and inorganic ions) and a kinetic multilayer module for diffusion limited transport of compounds between the gas phase, particle surface and particle bulk phase. In this article we describe and use ADCHAM to study: 1) the mass transfer limited uptake of ammonia (NH3) and formation of organic salts between ammonium (NH4+) and carboxylic acids (RCOOH), 2) the slow and almost particle size independent evaporation of α-pinene secondary organic aerosol (SOA) particles, and 3) the influence of chamber wall effects on the observed SOA formation in smog chambers.

  4. Heavy duty diesel engine exhaust aerosol particle and ion measurements.

    PubMed

    Lähde, Tero; Rönkkö, Topi; Virtanen, Annele; Schuck, Tanja J; Pirjola, Liisa; Hämeri, Kaarle; Kulmala, Markku; Arnold, Frank; Rothe, Dieter; Keskinen, Jorma

    2009-01-01

    Heavy duty EURO 4 diesel engine exhaust particle and ion size distributions were measured atthetailpipe using dynamometer testing. Measurements of particle volatility and electrical charge were undertaken to clarify diesel exhaust nucleation mode characteristics with different exhaust after-treatment systems. Nucleation mode particle volatility and charging probability were dependent on exhaust after-treatment particles were volatile and uncharged when the engine was equipped with diesel particulate filter and partly volatile and partly charged in exhaust without any after-treatment or with an oxidation catalyst only. The absence of charged particles in the nucleation mode of diesel particulate filtered exhaust excludes the ion mediated process as a nucleation particle formation mechanism.

  5. Phase, composition and growth mechanism for secondary organic aerosol from the ozonolysis of α-cedrene

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Wingen, L. M.; Perraud, V.; Finlayson-Pitts, B. J.

    2015-12-01

    Sesquiterpenes are an important class of biogenic volatile organic compounds (BVOCs) and have a high secondary organic aerosol (SOA) forming potential. However, SOA formation from sesquiterpene oxidation has received less attention compared to other BVOCs such as monoterpenes, and the underlying mechanisms remain poorly understood. In this work, we present a comprehensive experimental investigation of the ozonolysis of α-cedrene both in a glass flow reactor (27-44 s reaction times) and in static Teflon chambers (30-60 min reaction times). The SOA was collected by impaction or filters, followed by analysis using attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and electrospray ionization mass spectrometry (ESI-MS), or measured on line using direct analysis in real time (DART-MS) and aerosol mass spectrometry (AMS). The slow evaporation of 2-ethylhexyl nitrate that was incorporated into the SOA during its formation and growth gives an estimated diffusion coefficient of 3 × 10-15 cm2 s-1 and shows that SOA is a highly viscous semi-solid. Possible structures of four newly observed low molecular weight (MW ≤ 300 Da) reaction products with higher oxygen content than those previously reported were identified. High molecular weight (HMW) products formed in the early stages of the oxidation have structures consistent with aldol condensation products, peroxyhemiacetals, and esters. The size-dependent distributions of HMW products in the SOA, as well as the effects of stabilized Criegee intermediate (SCI) scavengers on HMW products and particle formation, confirm that HMW products and reactions of Criegee intermediates play a crucial role in early stages of particle formation. Our studies provide new insights into mechanisms of SOA formation and growth in α-cedrene ozonolysis and the important role of sesquiterpenes in new particle formation as suggested by field measurements.

  6. Phase, composition, and growth mechanism for secondary organic aerosol from the ozonolysis of α-cedrene

    NASA Astrophysics Data System (ADS)

    Zhao, Yue; Wingen, Lisa M.; Perraud, Véronique; Finlayson-Pitts, Barbara J.

    2016-03-01

    Sesquiterpenes are an important class of biogenic volatile organic compounds (BVOCs) and have a high secondary organic aerosol (SOA) forming potential. However, SOA formation from sesquiterpene oxidation has received less attention compared to other BVOCs such as monoterpenes, and the underlying mechanisms remain poorly understood. In this work, we present a comprehensive experimental investigation of the ozonolysis of α-cedrene both in a glass flow reactor (27-44 s reaction times) and in static Teflon chambers (30-60 min reaction times). The SOA was collected by impaction or filters, followed by analysis using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and electrospray ionization mass spectrometry (ESI-MS), or measured online using direct analysis in real-time mass spectrometry (DART-MS) and aerosol mass spectrometry (AMS). The slow evaporation of 2-ethylhexyl nitrate that was incorporated into the SOA during its formation and growth gives an estimated diffusion coefficient of 3 × 10-15 cm2 s-1 and shows that SOA is a highly viscous semisolid. Possible structures of four newly observed low molecular weight (MW ≤ 300 Da) reaction products with higher oxygen content than those previously reported were identified. High molecular weight (HMW) products formed in the early stages of the oxidation have structures consistent with aldol condensation products, peroxyhemiacetals, and esters. The size-dependent distributions of HMW products in the SOA, as well as the effects of stabilized Criegee intermediate (SCI) scavengers on HMW products and particle formation, confirm that HMW products and reactions of SCI play a crucial role in early stages of particle formation. Our studies provide new insights into mechanisms of SOA formation and growth in α-cedrene ozonolysis and the important role of sesquiterpenes in new particle formation as suggested by field measurements.

  7. The weather dependence of particle size distribution of indoor radioactive aerosol associated with radon decay products.

    PubMed

    Mostafa, A M A; Tamaki, K; Moriizumi, J; Yamazawa, H; Iida, T

    2011-07-01

    This study was performed to measure the activity size distribution of aerosol particles associated with short-lived radon decay products in indoor air at Nagoya University, Nagoya, Japan. The measurements were performed using a low pressure Andersen cascade impactor under variable meteorological conditions. The results showed that the greatest activity fraction was associated with aerosol particles in the accumulation size range (100-1000 nm) with a small fraction of nucleation mode (10-100 nm). Regarding the influence of the weather conditions, the decrease in the number of accumulation particles was observed clearly after rainfall without significant change in nucleation particles, which may be due to a washout process for the large particles.

  8. Ice cloud processing of ultra-viscous/glassy aerosol particles leads to enhanced ice nucleation ability

    NASA Astrophysics Data System (ADS)

    Wagner, R.; Möhler, O.; Saathoff, H.; Schnaiter, M.; Skrotzki, J.; Leisner, T.; Wilson, T. W.; Malkin, T. L.; Murray, B. J.

    2012-04-01

    The ice nucleation potential of airborne glassy aqueous aerosol particles has been investigated by controlled expansion cooling cycles in the AIDA aerosol and cloud chamber of the Karlsruhe Institute of Technology at temperatures between 247 and 216 K. Four different solutes were used as proxies for oxygenated organic matter found in the atmosphere: raffinose, 4-hydroxy-3-methoxy-DL-mandelic acid (HMMA), levoglucosan, and a multi-component mixture of raffinose with five dicarboxylic acids and ammonium sulphate. Similar to previous experiments with citric acid aerosols, all particles were found to nucleate ice heterogeneously before reaching the homogeneous freezing threshold provided that the freezing cycles were started well below the respective glass transition temperatures of the compounds; this is discussed in detail in a separate article. In this contribution, we identify a further mechanism by which glassy aerosols can promote ice nucleation below the homogeneous freezing limit. If the glassy aerosol particles are probed in freezing cycles started only a few degrees below their respective glass transition temperatures, they enter the liquid regime of the state diagram upon increasing relative humidity (moisture-induced glass-to-liquid transition) before being able to act as heterogeneous ice nuclei. Ice formation then only occurs by homogeneous freezing at elevated supersaturation levels. When ice forms the remaining solution freeze concentrates and re-vitrifies. If these ice cloud processed glassy aerosol particles are then probed in a second freezing cycle at the same temperature, they catalyse ice formation at a supersaturation threshold between 5 and 30% with respect to ice. By analogy with the enhanced ice nucleation ability of insoluble ice nuclei like mineral dusts after they nucleate ice once, we refer to this phenomenon as pre-activation. We propose a number of possible explanations for why glassy aerosols that have re-vitrified in contact with the

  9. Measurement of particle size characteristics of metered dose inhaler (MDI) aerosols.

    PubMed

    Dolovich, M

    1991-01-01

    Measurement of the aerodynamic size of an aerosol allows a prediction of its deposition efficiency and behaviour in the lung. The dynamics of volatile or pressurized (MDI) aerosols presents problems not encountered in the characterization of solid or liquid particles alone. For example, the data obtained in real-time sampling as opposed to measuring an aged aerosol provide a truer representation of circumstances during actual clinical use, yet this may be difficult to achieve due to propellent evaporation. A number of particle sizing systems have been developed based upon light scattering techniques and aerodynamic principles. Each method has its limitations; in general, they successfully measure the aerodynamic size distributions of MDI aerosols. Cascade impactors, the "gold standard" of the industry have the advantage that they allow analysis of drug mass as well as other tracers within the aerosol, but the process as a whole is labour intensive, with limited resolution. Highly automated laser-based systems developed over the past 10 years measure the surface characteristics of the aerosol rather than the direct measurement of mass. Because of different values obtained from various sizing systems, it is suggested that all MDI drugs be sized using cascade impactors but that parallel data be obtained using an alternative sizing system.

  10. Measurements of mesospheric aerosol particles during the ECOMA/MASS campaign 2007.

    NASA Astrophysics Data System (ADS)

    Strelnikova, Irina; Rapp, Markus; Strelnikov, Boris; Latteck, Ralph; Baumgarten, Gerd; Brattli, Alvin; Friedrich, Martin; Gumbel, Jorg; Robertson, Scott

    In August 2007 the joint European-American ECOMA/MASS (Existence and Charge state Of Meteoric smoke particles in the middle Atmosphere/Dust MASS Analyzer) sounding rocket and ground-based campaign took place at the Andøya Rocket Range (ARR) (69° N). This campaign was devoted to the investigation of mesospheric aerosol particles. During this campaign, three instrumented sounding rockets were launched under the PMSE and NLC conditions. All rockets were carrying instruments to characterize mesospheric aerosol particles and their environment. The ECOMA rocket was launched during the first salvo shortly (30 min) after the MASS payload. At that time, the EISCAT (69° N, 19° E) VHF and ALWIN radars observed a double layered PMSE. Also an NLC layer was detected by lidar and photometers onboard each rocket. The main instrument of the ECOMA payload is the "ECOMA particle detector". This instrument comprises a classical Faraday cup with a xenon-flash lamp for the active photoionization/photodetachment of mesospheric smoke particles (MSPs) and the subsequent detection of corresponding photoelectrons. Comparing direct Faraday cup measurements and photocurrents we are able to derive particle properties like number densities and particle radii. We present the results of these measurements that show the presence of aerosol particles inside the NLC and PMSE layer, but not below or above these layers. These results are consistent with model predictions, which account for global transport of meteoric smoke. This implies that ice nucleation in the polar summer needs to be reconsidered.

  11. Polarization properties of aerosol particles over western Japan: classification, seasonal variation, and implications for air quality

    NASA Astrophysics Data System (ADS)

    Pan, Xiaole; Uno, Itsushi; Hara, Yukari; Osada, Kazuo; Yamamoto, Shigekazu; Wang, Zhe; Sugimoto, Nobuo; Kobayashi, Hiroshi; Wang, Zifa

    2016-08-01

    Ground-based observation of the polarization properties of aerosol particles using a polarization optical particle counter (POPC) was made from 27 October 2013, to 31 December 2015, at a suburban site in the Kyushu area of Japan. We found that the depolarization ratio (DR, the fraction of s-polarized signal in the total backward light scattering signal) of aerosol particles showed prominent seasonal variability, with peaks in spring (0.21-0.23) and winter (0.19-0.23), and a minimum value (0.09-0.14) in summer. The aerosol compositions in both fine mode (aerodynamic diameter of particle, Dp < 2.5 µm) and coarse mode (2.5 µm < Dp < 10 µm), and the size-dependent polarization characteristics were analyzed for long-range transport dust particles, sea salt, and anthropogenic pollution-dominant aerosols. The DR value increased with increasing particle size, and DR = 0.1 was a reliable threshold value to identify the sphericity of supermicron (Dp > 1 µm) particles. Occurrence of substandard air quality days in Kyushu was closely related with mixed type (coexistence of anthropogenic pollutants and dust particles in the atmosphere), especially in winter and spring, indicating that dust events in the Asian continent played a key role in the cross-boundary transport of continental pollution. Backward trajectory analysis demonstrated that air masses originating from the western Pacific contained large amounts of spherical particles due to the influence of sea salt, especially in summer; however, for air masses from the Asian continent, the dependence of number fraction of spherical particles on air relative humidity was insignificant, indicating the predominance of less-hygroscopic substances (e.g., mineral dust), although the mass concentrations of anthropogenic pollutants were elevated.

  12. Characterizing the impact of urban emissions on regional aerosol particles; airborne measurements during the MEGAPOLI experiment

    NASA Astrophysics Data System (ADS)

    Freney, E. J.; Sellegri, K.; Canonaco, F.; Colomb, A.; Borbon, A.; Michoud, V.; Doussin, J.-F.; Crumeyrolle, S.; Amarouch, N.; Pichon, J.-M.; Prévôt, A. S. H.; Beekmann, M.; Schwarzenböeck, A.

    2013-09-01

    The MEGAPOLI experiment took place in July 2009. The aim of this campaign was to study the aging and reactions of aerosol and gas-phase emissions in the city of Paris. Three ground-based measurement sites and several mobile platforms including instrument equipped vehicles and the ATR-42 aircraft were involved. We present here the variations in particle- and gas-phase species over the city of Paris using a combination of high-time resolution measurements aboard the ATR-42 aircraft. Particle chemical composition was measured using a compact time-of-flight aerosol mass spectrometer (C-ToF-AMS) giving detailed information of the non-refractory submicron aerosol species. The mass concentration of BC, measured by a particle absorption soot photometer (PSAP), was used as a marker to identify the urban pollution plume boundaries. Aerosol mass concentrations and composition were affected by air-mass history, with air masses that spent longest time over land having highest fractions of organic aerosol and higher total mass concentrations. The Paris plume is mainly composed of organic aerosol (OA), black carbon and nitrate aerosol, as well as high concentrations of anthropogenic gas-phase species such as toluene, benzene, and NOx. Using BC and CO as tracers for air-mass dilution, we observe the ratio of ΔOA / ΔBC and ΔOA / ΔCO increase with increasing photochemical age (-log(NOx / NOy). Plotting the equivalent ratios for the Positive Matrix Factorization (PMF) resolved species (LV-OOA, SV-OOA, and HOA) illustrate that the increase in OA is a result of secondary organic aerosol (SOA). Within Paris the changes in the ΔOA / ΔCO are similar to those observed during other studies in Mexico city, Mexico and in New England, USA. Using the measured VOCs species together with recent organic aerosol formation yields we predicted ~ 50% of the measured organics. These airborne measurements during the MEGAPOLI experiment show that urban emissions contribute to the formation of OA

  13. Characterizing the impact of urban emissions on regional aerosol particles: airborne measurements during the MEGAPOLI experiment

    NASA Astrophysics Data System (ADS)

    Freney, E. J.; Sellegri, K.; Canonaco, F.; Colomb, A.; Borbon, A.; Michoud, V.; Doussin, J.-F.; Crumeyrolle, S.; Amarouche, N.; Pichon, J.-M.; Bourianne, T.; Gomes, L.; Prevot, A. S. H.; Beekmann, M.; Schwarzenböeck, A.

    2014-02-01

    The MEGAPOLI (Megacities: Emissions, urban, regional and Global Atmospheric POLlution and climate effects, and Integrated tools for assessment and mitigation) experiment took place in July 2009. The aim of this campaign was to study the aging and reactions of aerosol and gas-phase emissions in the city of Paris. Three ground-based measurement sites and several mobile platforms including instrument equipped vehicles and the ATR-42 aircraft were involved. We present here the variations in particle- and gas-phase species over the city of Paris, using a combination of high-time resolution measurements aboard the ATR-42 aircraft. Particle chemical composition was measured using a compact time-of-flight aerosol mass spectrometer (C-ToF-AMS), giving detailed information on the non-refractory submicron aerosol species. The mass concentration of black carbon (BC), measured by a particle absorption soot photometer (PSAP), was used as a marker to identify the urban pollution plume boundaries. Aerosol mass concentrations and composition were affected by air-mass history, with air masses that spent longest time over land having highest fractions of organic aerosol and higher total mass concentrations. The Paris plume is mainly composed of organic aerosol (OA), BC, and nitrate aerosol, as well as high concentrations of anthropogenic gas-phase species such as toluene, benzene, and NOx. Using BC and CO as tracers for air-mass dilution, we observe the ratio of ΔOA / ΔBC and ΔOA / ΔCO increase with increasing photochemical age (-log(NOx / NOy)). Plotting the equivalent ratios of different organic aerosol species (LV-OOA, SV-OOA, and HOA) illustrate that the increase in OA is a result of secondary organic aerosol (SOA) formation. Within Paris the changes in the ΔOA / ΔCO are similar to those observed during other studies in London, Mexico City, and in New England, USA. Using the measured SOA volatile organic compounds (VOCs) species together with organic aerosol formation

  14. Effect of particle settling on lidar profiles of long-range transported Saharan aerosols

    NASA Astrophysics Data System (ADS)

    Gasteiger, Josef; Groß, Silke

    2016-04-01

    A large amount of desert aerosol is transported in the Saharan Air Layer (SAL) westwards from Africa over the Atlantic Ocean. Lidar profiles of transported Saharan aerosol may contain some information about the vertically-resolved aerosol microphysics that could be used to characterize processes that affected the measured aerosol during transport. We present modelled lidar profiles of long-range transported Saharan aerosol assuming that initially the SAL is well-mixed and that there is no vertical mixing of air within the SAL as soon as it reaches the Atlantic. We consider Stokes gravitational settling of aerosol particles over the ocean. The lidar profiles are calculated using optical models for irregularly-shaped mineral dust particles assuming settling-induced particle removal as function of distance from the SAL top. Within the SAL we find a decrease of both the backscatter coefficients and the linear depolarization ratios with decreasing distance from the SAL top. For example, the linear depolarization ratio at a wavelength of 532nm decreases from 0.289 at 1000m to 0.256 at 200m and 0.215 at 100m below SAL top. We compare the modelled backscatter coefficients and linear depolarization ratios to ground-based lidar measurements performed during the SALTRACE field campaign in Barbados (Caribbean) and find agreement within the estimated uncertainties. We discuss the uncertainties of our modeling approach in our presentation. Assumed mineral dust particle shapes, assumed particle mixture properties, and assumptions about processes in the SAL over the continent and the ocean are important aspects to be considered. Uncertainties are relevant for the potential of lidar measurements of transported Saharan dust to learn something about processes occuring in the SAL during long-range transport. We also compare our modeling results to modeling results previously published in the literature.

  15. Size distribution dynamics reveal particle-phase chemistry in organic aerosol formation.

    PubMed

    Shiraiwa, Manabu; Yee, Lindsay D; Schilling, Katherine A; Loza, Christine L; Craven, Jill S; Zuend, Andreas; Ziemann, Paul J; Seinfeld, John H

    2013-07-16

    Organic aerosols are ubiquitous in the atmosphere and play a central role in climate, air quality, and public health. The aerosol size distribution is key in determining its optical properties and cloud condensation nucleus activity. The dominant portion of organic aerosol is formed through gas-phase oxidation of volatile organic compounds, so-called secondary organic aerosols (SOAs). Typical experimental measurements of SOA formation include total SOA mass and atomic oxygen-to-carbon ratio. These measurements, alone, are generally insufficient to reveal the extent to which condensed-phase reactions occur in conjunction with the multigeneration gas-phase photooxidation. Combining laboratory chamber experiments and kinetic gas-particle modeling for the dodecane SOA system, here we show that the presence of particle-phase chemistry is reflected in the evolution of the SOA size distribution as well as its mass concentration. Particle-phase reactions are predicted to occur mainly at the particle surface, and the reaction products contribute more than half of the SOA mass. Chamber photooxidation with a midexperiment aldehyde injection confirms that heterogeneous reaction of aldehydes with organic hydroperoxides forming peroxyhemiacetals can lead to a large increase in SOA mass. Although experiments need to be conducted with other SOA precursor hydrocarbons, current results demonstrate coupling between particle-phase chemistry and size distribution dynamics in the formation of SOAs, thereby opening up an avenue for analysis of the SOA formation process.

  16. Ultrasensitive detection of inhaled organic aerosol particles by accelerator mass spectrometry.

    PubMed

    Parkhomchuk, E V; Gulevich, D G; Taratayko, A I; Baklanov, A M; Selivanova, A V; Trubitsyna, T A; Voronova, I V; Kalinkin, P N; Okunev, A G; Rastigeev, S A; Reznikov, V A; Semeykina, V S; Sashkina, K A; Parkhomchuk, V V

    2016-09-01

    Accelerator mass spectrometry (AMS) was shown to be applicable for studying the penetration of organic aerosols, inhaled by laboratory mice at ultra-low concentration ca. 10(3) cm(-3). We synthesized polystyrene (PS) beads, composed of radiocarbon-labeled styrene, for testing them as model organic aerosols. As a source of radiocarbon we used methyl alcohol with radioactivity. Radiolabeled polystyrene beads were obtained by emulsifier-free emulsion polymerization of synthesized (14)C-styrene initiated by K2S2O8 in aqueous media. Aerosol particles were produced by pneumatic spraying of diluted (14)C-PS latex. Mice inhaled (14)C-PS aerosol consisting of the mix of 10(3) 225-nm particles per 1 cm(3) and 5·10(3) 25-nm particles per 1 cm(3) for 30 min every day during five days. Several millions of 225-nm particles deposited in the lungs and slowly excreted from them during two weeks of postexposure. Penetration of particles matter was also observed for liver, kidneys and brain, but not for a heart. PMID:27281540

  17. Size distribution dynamics reveal particle-phase chemistry in organic aerosol formation.

    PubMed

    Shiraiwa, Manabu; Yee, Lindsay D; Schilling, Katherine A; Loza, Christine L; Craven, Jill S; Zuend, Andreas; Ziemann, Paul J; Seinfeld, John H

    2013-07-16

    Organic aerosols are ubiquitous in the atmosphere and play a central role in climate, air quality, and public health. The aerosol size distribution is key in determining its optical properties and cloud condensation nucleus activity. The dominant portion of organic aerosol is formed through gas-phase oxidation of volatile organic compounds, so-called secondary organic aerosols (SOAs). Typical experimental measurements of SOA formation include total SOA mass and atomic oxygen-to-carbon ratio. These measurements, alone, are generally insufficient to reveal the extent to which condensed-phase reactions occur in conjunction with the multigeneration gas-phase photooxidation. Combining laboratory chamber experiments and kinetic gas-particle modeling for the dodecane SOA system, here we show that the presence of particle-phase chemistry is reflected in the evolution of the SOA size distribution as well as its mass concentration. Particle-phase reactions are predicted to occur mainly at the particle surface, and the reaction products contribute more than half of the SOA mass. Chamber photooxidation with a midexperiment aldehyde injection confirms that heterogeneous reaction of aldehydes with organic hydroperoxides forming peroxyhemiacetals can lead to a large increase in SOA mass. Although experiments need to be conducted with other SOA precursor hydrocarbons, current results demonstrate coupling between particle-phase chemistry and size distribution dynamics in the formation of SOAs, thereby opening up an avenue for analysis of the SOA formation process. PMID:23818634

  18. Size distribution dynamics reveal particle-phase chemistry in organic aerosol formation

    PubMed Central

    Shiraiwa, Manabu; Yee, Lindsay D.; Schilling, Katherine A.; Loza, Christine L.; Craven, Jill S.; Zuend, Andreas; Ziemann, Paul J.; Seinfeld, John H.

    2013-01-01

    Organic aerosols are ubiquitous in the atmosphere and play a central role in climate, air quality, and public health. The aerosol size distribution is key in determining its optical properties and cloud condensation nucleus activity. The dominant portion of organic aerosol is formed through gas-phase oxidation of volatile organic compounds, so-called secondary organic aerosols (SOAs). Typical experimental measurements of SOA formation include total SOA mass and atomic oxygen-to-carbon ratio. These measurements, alone, are generally insufficient to reveal the extent to which condensed-phase reactions occur in conjunction with the multigeneration gas-phase photooxidation. Combining laboratory chamber experiments and kinetic gas-particle modeling for the dodecane SOA system, here we show that the presence of particle-phase chemistry is reflected in the evolution of the SOA size distribution as well as its mass concentration. Particle-phase reactions are predicted to occur mainly at the particle surface, and the reaction products contribute more than half of the SOA mass. Chamber photooxidation with a midexperiment aldehyde injection confirms that heterogeneous reaction of aldehydes with organic hydroperoxides forming peroxyhemiacetals can lead to a large increase in SOA mass. Although experiments need to be conducted with other SOA precursor hydrocarbons, current results demonstrate coupling between particle-phase chemistry and size distribution dynamics in the formation of SOAs, thereby opening up an avenue for analysis of the SOA formation process. PMID:23818634

  19. Modeling Gas-Particle Partitioning of SOA: Effects of Aerosol Physical State and RH

    NASA Astrophysics Data System (ADS)

    Zuend, A.; Seinfeld, J.

    2011-12-01

    Aged tropospheric aerosol particles contain mixtures of inorganic salts, acids, water, and a large variety of organic compounds. In liquid aerosol particles non-ideal mixing of all species determines whether the condensed phase undergoes liquid-liquid phase separation or whether it is stable in a single mixed phase, and whether it contains solid salts in equilibrium with their saturated solution. The extended thermodynamic model AIOMFAC is able to predict such phase states by representing the variety of organic components using functional groups within a group-contribution concept. The number and composition of different condensed phases impacts the diversity of reaction media for multiphase chemistry and the gas-particle partitioning of semivolatile species. Recent studies show that under certain conditions biogenic and other organic-rich particles can be present in a highly viscous, semisolid or amorphous solid physical state, with consequences regarding reaction kinetics and mass transfer limitations. We present results of new gas-particle partitioning computations for aerosol chamber data using a model based on AIOMFAC activity coefficients and state-of-the-art vapor pressure estimation methods. Different environmental conditions in terms of temperature, relative humidity (RH), salt content, amount of precursor VOCs, and physical state of the particles are considered. We show how modifications of absorptive and adsorptive gas-particle mass transfer affects the total aerosol mass in the calculations and how the results of these modeling approaches compare to data of aerosol chamber experiments, such as alpha-pinene oxidation SOA. For a condensed phase in a mixed liquid state containing ammonium sulfate, the model predicts liquid-liquid phase separation up to high RH in case of, on average, moderately hydrophilic organic compounds, such as first generation oxidation products of alpha-pinene. The computations also reveal that treating liquid phases as ideal

  20. Sources and characteristics of fine particles over the Yellow Sea and Bohai Sea using online single particle aerosol mass spectrometer.

    PubMed

    Fu, Huaiyu; Zheng, Mei; Yan, Caiqing; Li, Xiaoying; Gao, Huiwang; Yao, Xiaohong; Guo, Zhigang; Zhang, Yuanhang

    2015-03-01

    Marine aerosols over the East China Seas are heavily polluted by continental sources. During the Chinese Comprehensive Ocean Experiment in November 2012, size and mass spectra of individual atmospheric particles in the size range from 0.2 to 2.0 μm were measured on board by a single particle aerosol mass spectrometer (SPAMS). The average hourly particle number (PN) was around 4560±3240 in the South Yellow Sea (SYS), 2900±3970 in the North Yellow Sea (NYS), and 1700±2220 in the Bohai Sea (BS). PN in NYS and BS varied greatly over 3 orders of magnitude, while that in SYS varied slightly. The size distributions were fitted with two log-normal modes. Accumulation mode dominated in NYS and BS, especially during episodic periods. Coarse mode particles played an important role in SYS. Particles were classified using an adaptive resonance theory based neural network algorithm (ART-2a). Six particle types were identified with secondary-containing, aged sea-salt, soot-like, biomass burning, fresh sea-salt, and lead-containing particles accounting for 32%, 21%, 18%, 16%, 4%, and 3% of total PN, respectively. Aerosols in BS were relatively enriched in particles from anthropogenic sources compared to SYS, probably due to emissions from more developed upwind regions and indicating stronger influence of continental outflow on marine environment. Variation of source types depended mainly on origins of transported air masses. This study examined rapid changes in PN, size distribution and source types of fine particles in marine atmospheres. It also demonstrated the effectiveness of high-time-resolution source apportionment by ART-2a.

  1. Sources and characteristics of fine particles over the Yellow Sea and Bohai Sea using online single particle aerosol mass spectrometer.

    PubMed

    Fu, Huaiyu; Zheng, Mei; Yan, Caiqing; Li, Xiaoying; Gao, Huiwang; Yao, Xiaohong; Guo, Zhigang; Zhang, Yuanhang

    2015-03-01

    Marine aerosols over the East China Seas are heavily polluted by continental sources. During the Chinese Comprehensive Ocean Experiment in November 2012, size and mass spectra of individual atmospheric particles in the size range from 0.2 to 2.0 μm were measured on board by a single particle aerosol mass spectrometer (SPAMS). The average hourly particle number (PN) was around 4560±3240 in the South Yellow Sea (SYS), 2900±3970 in the North Yellow Sea (NYS), and 1700±2220 in the Bohai Sea (BS). PN in NYS and BS varied greatly over 3 orders of magnitude, while that in SYS varied slightly. The size distributions were fitted with two log-normal modes. Accumulation mode dominated in NYS and BS, especially during episodic periods. Coarse mode particles played an important role in SYS. Particles were classified using an adaptive resonance theory based neural network algorithm (ART-2a). Six particle types were identified with secondary-containing, aged sea-salt, soot-like, biomass burning, fresh sea-salt, and lead-containing particles accounting for 32%, 21%, 18%, 16%, 4%, and 3% of total PN, respectively. Aerosols in BS were relatively enriched in particles from anthropogenic sources compared to SYS, probably due to emissions from more developed upwind regions and indicating stronger influence of continental outflow on marine environment. Variation of source types depended mainly on origins of transported air masses. This study examined rapid changes in PN, size distribution and source types of fine particles in marine atmospheres. It also demonstrated the effectiveness of high-time-resolution source apportionment by ART-2a. PMID:25766014

  2. Dynamic Particle Growth Testing - Phase I Studies

    SciTech Connect

    Hu, M.Z-C.

    2001-05-17

    There is clearly a great need to understand the processes of crystallization and solid scale formation that led to the shutdown of 2H evaporator operation at the Savannah River Site (SRS) and could possibly cause similar problems in the future in other evaporators. Waste streams from SRS operations that enter the evaporators generally contain alkaline, sodium nitrate/nitrite-based solutions with various changing concentrations of silicates and aluminates. It has been determined. that the silicates and aluminates served as precursor reactants for forming unwanted minerals during solution evaporation, upon transport, or upon storage. Mineral forms of the Zeolite Linde A group--sodalites and cancrinite--along with gibbsite, have often been identified as contributing to deposit (scale) formation on surfaces of the 2H evaporator as well as to the formation of solid plugs in the gravity drain line and lift line. Meanwhile, solids (amorphous or crystalline minerals) are believed, without direct evidence, to form in the bulk solutions in the evaporator. In addition, the position of deposits in the 2H evaporator suggests that scale formation depends on the interplay of heat and mass transfer, hydrodynamics, and reaction mechanisms and kinetics. The origin of solid scale formation on walls could be due to heterogeneous nucleation and/or to homogeneous nucleation followed by cluster/particle deposition. Preliminary laboratory tests at the Savannah River Technology Center (SRTC) with standing metal coupons seem to support the latter mechanism for initial deposition; that is, the solid particles form in the bulk solution first and then deposit on the metal surfaces. Further buildup of deposits may involve both mechanisms: deposition and crystal growth. Therefore, there may be a direct linkage between the solid particle growth in bulk solution and the scale buildup on the wall surfaces. On the other hand, even if scale formation is due solely to a heterogeneous mechanism

  3. Effects of amines on formation of sub-3 nm particles and their subsequent growth

    SciTech Connect

    Yu H.; McGraw R.; Lee S.-H.

    2012-01-28

    Field observations and quantum chemical calculations suggest that amines can be important for formation of nanometer size particles. Amines and ammonia often have common atmospheric emission sources and the similar chemical and physical properties. While the effects of ammonia on aerosol nucleation have been previously investigated, laboratory studies of homogeneous nucleation involving amines are lacking. We have made kinetics studies of multicomponent nucleation (MCN) with sulfuric acid, water, ammonia and amines under conditions relevant to the atmosphere. Low concentrations of aerosol precursors were measured with chemical ionization mass spectrometers (CIMS) to provide constrained precursor concentrations needed for nucleation. Particle sizes larger than {approx}2 nm were measured with a nano-differential mobility analyzer (nano-DMA), and number concentrations of particles larger than {approx}1 nm were measured with a particle size magnifier (PSM). Our observations provide the laboratory evidence that amines indeed can participate in aerosol nucleation and growth at the molecular cluster level. The enhancement of particle number concentrations due to several atmospherically relevant amine compounds and ammonia were related to the basicity of these compounds, indicating that acid-base reactions may contribute to the formation of sub-3 nm particles.

  4. Effects of amines on formation of sub-3 nm particles and their subsequent growth

    NASA Astrophysics Data System (ADS)

    Yu, Huan; McGraw, Robert; Lee, Shan-Hu

    2012-01-01

    Field observations and quantum chemical calculations suggest that amines can be important for formation of nanometer size particles. Amines and ammonia often have common atmospheric emission sources and the similar chemical and physical properties. While the effects of ammonia on aerosol nucleation have been previously investigated, laboratory studies of homogeneous nucleation involving amines are lacking. We have made kinetics studies of multicomponent nucleation (MCN) with sulfuric acid, water, ammonia and amines under conditions relevant to the atmosphere. Low concentrations of aerosol precursors were measured with chemical ionization mass spectrometers (CIMS) to provide constrained precursor concentrations needed for nucleation. Particle sizes larger than ˜2 nm were measured with a nano-differential mobility analyzer (nano-DMA), and number concentrations of particles larger than ˜1 nm were measured with a particle size magnifier (PSM). Our observations provide the laboratory evidence that amines indeed can participate in aerosol nucleation and growth at the molecular cluster level. The enhancement of particle number concentrations due to several atmospherically relevant amine compounds and ammonia were related to the basicity of these compounds, indicating that acid-base reactions may contribute to the formation of sub-3 nm particles.

  5. Individual Aerosol Particles from Biomass Burning in Southern Africa Compositions and Aging of Inorganic Particles. 2; Compositions and Aging of Inorganic Particles

    NASA Technical Reports Server (NTRS)

    Li, Jia; Posfai, Mihaly; Hobbs, Peter V.; Buseck, Peter R.

    2003-01-01

    Individual aerosol particles collected over southern Africa during the SAFARI 2000 field study were studied using transmission electron microscopy and field-emission scanning electron microscopy. The sizes, shapes, compositions, mixing states, surface coatings, and relative abundances of aerosol particles from biomass burning, in boundary layer hazes, and in the free troposphere were compared, with emphasis on aging and reactions of inorganic smoke particles. Potassium salts and organic particles were the predominant species in the smoke, and most were internally mixed. More KCl particles occur in young smoke, whereas more K2SO4 and KNO3 particles were present in aged smoke. This change indicates that with the aging of the smoke, KCl particles from the fires were converted to K2SO4 and KNO3 through reactions with sulfur- and nitrogen- bearing species from biomass burning as well as other sources. More soot was present in smoke from flaming grass fires than bush and wood fires, probably due to the predominance of flaming combustion in grass fires. The high abundance of organic particles and soluble salts can affect the hygroscopic properties of biomass-burning aerosols and therefore influence their role as cloud condensation nuclei. Particles from biomass burning were important constituents of the regional hazes.

  6. The single scattering properties of the aerosol particles as aggregated spheres

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Gu, X.; Cheng, T.; Xie, D.; Yu, T.; Chen, H.; Guo, J.

    2012-08-01

    The light scattering and absorption properties of anthropogenic aerosol particles such as soot aggregates are complicated in the temporal and spatial distribution, which introduce uncertainty of radiative forcing on global climate change. In order to study the single scattering properties of anthorpogenic aerosol particles, the structures of these aerosols such as soot paticles and soot-containing mixtures with the sulfate or organic matter, are simulated using the parallel diffusion limited aggregation algorithm (DLA) based on the transmission electron microscope images (TEM). Then, the single scattering properties of randomly oriented aerosols, such as scattering matrix, single scattering albedo (SSA), and asymmetry parameter (AP), are computed using the superposition T-matrix method. The comparisons of the single scattering properties of these specific types of clusters with different morphological and chemical factors such as fractal parameters, aspect ratio, monomer radius, mixture mode and refractive index, indicate that these different impact factors can respectively generate the significant influences on the single scattering properties of these aerosols. The results show that aspect ratio of circumscribed shape has relatively small effect on single scattering properties, for both differences of SSA and AP are less than 0.1. However, mixture modes of soot clusters with larger sulfate particles have remarkably important effects on the scattering and absorption properties of aggregated spheres, and SSA of those soot-containing mixtures are increased in proportion to the ratio of larger weakly absorbing attachments. Therefore, these complex aerosols come from man made pollution cannot be neglected in the aerosol retrievals. The study of the single scattering properties on these kinds of aggregated spheres is important and helpful in remote sensing observations and atmospheric radiation balance computations.

  7. Stable Carbon Fractionation In Size Segregated Aerosol Particles Produced By Controlled Biomass Burning

    NASA Astrophysics Data System (ADS)

    Masalaite, Agne; Garbaras, Andrius; Garbariene, Inga; Ceburnis, Darius; Martuzevicius, Dainius; Puida, Egidijus; Kvietkus, Kestutis; Remeikis, Vidmantas

    2014-05-01

    Biomass burning is the largest source of primary fine fraction carbonaceous particles and the second largest source of trace gases in the global atmosphere with a strong effect not only on the regional scale but also in areas distant from the source . Many studies have often assumed no significant carbon isotope fractionation occurring between black carbon and the original vegetation during combustion. However, other studies suggested that stable carbon isotope ratios of char or BC may not reliably reflect carbon isotopic signatures of the source vegetation. Overall, the apparently conflicting results throughout the literature regarding the observed fractionation suggest that combustion conditions may be responsible for the observed effects. The purpose of the present study was to gather more quantitative information on carbonaceous aerosols produced in controlled biomass burning, thereby having a potential impact on interpreting ambient atmospheric observations. Seven different biomass fuel types were burned under controlled conditions to determine the effect of the biomass type on the emitted particulate matter mass and stable carbon isotope composition of bulk and size segregated particles. Size segregated aerosol particles were collected using the total suspended particle (TSP) sampler and a micro-orifice uniform deposit impactor (MOUDI). The results demonstrated that particle emissions were dominated by the submicron particles in all biomass types. However, significant differences in emissions of submicron particles and their dominant sizes were found between different biomass fuels. The largest negative fractionation was obtained for the wood pellet fuel type while the largest positive isotopic fractionation was observed during the buckwheat shells combustion. The carbon isotope composition of MOUDI samples compared very well with isotope composition of TSP samples indicating consistency of the results. The measurements of the stable carbon isotope ratio in

  8. The effect of phase partitioning of semivolatile compounds on the measured CCN activity of aerosol particles

    NASA Astrophysics Data System (ADS)

    Romakkaniemi, S.; Jaatinen, A.; Laaksonen, A.; Nenes, A.; Raatikainen, T.

    2013-09-01

    The effect of inorganic semivolatile aerosol compounds on the CCN activity of aerosol particles was studied by using a computational model for a DMT-CCN counter, a cloud parcel model for condensation kinetics and experiments to quantify the modelled results. Concentrations of water vapour and semivolatiles as well as aerosol trajectories in the CCN column were calculated by a computational fluid dynamics model. These trajectories and vapour concentrations were then used as an input for the cloud parcel model to simulate mass transfer kinetics of water and semivolatiles between aerosol particles and the gas phase. Two different questions were studied: (1) how big fraction of semivolatiles is evaporated from particles before activation in the CCN counter? (2) How much the CCN activity can be increased due to condensation of semivolatiles prior to the maximum water supersaturation in the case of high semivolatile concentration in the gas phase? The results show that, to increase the CCN activity of aerosol particles, a very high gas phase concentration (as compared to typical ambient conditions) is needed. We used nitric acid as a test compound. A concentration of several ppb or higher is needed for measurable effect. In the case of particle evaporation, we used ammonium nitrate as a test compound and found that it partially evaporates before maximum supersaturation is reached in the CCN counter, thus causing an underestimation of CCN activity. The effect of evaporation is clearly visible in all supersaturations, leading to an underestimation of the critical dry diameter by 10 to 15 nanometres in the case of ammonium nitrate particles in different supersaturations. This result was also confirmed by measurements in supersaturations between 0.1 and 0.7%.

  9. Determination of external and internal mixing of organic and inorganic aerosol components from equilibrium water uptake by sub-micrometer particles.

    NASA Astrophysics Data System (ADS)

    Aklilu, Y.; Mozurkewich, M.

    2002-12-01

    The ability of a particle to gain and lose water with changes in relative humidity is fundamental to particle's effectiveness as a cloud condensation nucleus, chemical reactivity, atmospheric residence time and influence on global radiation balance. We describe a method developed to measure particle hygroscopicity over a range of relative humidities (RH) from 50% to 85%. Ambient aerosol particles were dried, monodisperse particles with diameters of usually 50 and 114 nm were selected, and their size distribution following humidification was measured. We measured particle hygroscopicity at Golden Ears Provincial Park and Eagle Ridge Mountain as part of the Pacific 2001 field study in the lower Fraser Valley in August of 2001. The humidified size distributions were sometimes monomodal and sometimes bimodal distribution with less and more hygroscopic peaks. The hygroscopicity of the monomodal particles varied between that of the less and more hygroscopic particles. The less hygroscopic particles were probably almost entirely organic in composition; they had consistent growth curves with wet/dry diameter ratios that increased from 1.04 at 50% relative humidity to 1.09 at 80% RH. These less hygroscopic particles constituted almost all the sampled aerosol at the forested site in Golden Ears Park and during the rainy periods at Eagle Ridge. At other times there were more hygroscopic particles, either as a single mixed mode or as a distinct mode in addition to the less hygroscopic particles. These showed little growth below 70% RH and pronounced growth above 70%. The increased water sorption above 70% RH is likely due to the particles containing (NH4)3H(SO4)2 or (NH4)2(SO4), as these salts deliquesce at 70% and 80% RH, respectively. Since the growth of these particles was less than expected for the pure salts, we conclude that these particles consisted of a mixture of the organic and inorganic components. An estimate of the relative organic fraction was made using the

  10. A case study of urban particle acidity and its influence on secondary organic aerosol.

    PubMed

    Zhang, Qi; Jimenez, Jose L; Worsnop, Douglas R; Canagaratna, Manjula

    2007-05-01

    Size-resolved indicators of aerosol acidity, including H+ ion concentrations (H+Aer) and the ratio of stoichiometric neutralization are evaluated in submicrometer aerosols using highly time-resolved aerosol mass spectrometer (AMS) data from Pittsburgh. The pH and ionic strength within the aqueous particle phase are also estimated using the Aerosol Inorganics Model (AIM). Different mechanisms that contribute to the presence of acidic particles in Pittsburgh are discussed. The largest H+Aer loadings and lowest levels of stoichiometric neutralization were detected when PM1 loadings were high and dominated by SO4(2-). The average size distribution of H+Aer loading shows an accumulation mode at Dva approximately 600 nm and an enhanced smaller mode that centers at Dva approximately 200 nm and tails into smaller sizes. The acidity in the accumulation mode particles suggests that there is generally not enough gas-phase NH3 available on a regional scale to completely neutralize sulfate in Pittsburgh. The lack of stoichiometric neutralization in the 200 nm mode particles is likely caused by the relatively slow mixing of gas-phase NH3 into SO2-rich plumes containing younger particles. We examined the influence of particle acidity on secondary organic aerosol (SOA) formation by comparing the mass concentrations and size distributions of oxygenated organic aerosol (00A--surrogate for SOA in Pittsburgh) during periods when particles are, on average, acidic to those when particles are bulk neutralized. The average mass concentration of ODA during the acidic periods (3.1 +/- 1.7 microg m(-3)) is higher than that during the neutralized periods (2.5 +/- 1.3 microg m(-3)). Possible reasons for this enhancement include increased condensation of SOA species, acid-catalyzed SOA formation, and/or differences in air mass transport and history. However, even if the entire enhancement (approximately 0.6 microg m(-3)) can be attributed to acid catalysis, the upperbound increase of SOA mass

  11. Elucidating determinants of aerosol composition through particle-type-based receptor modeling

    NASA Astrophysics Data System (ADS)

    McGuire, M. L.; Jeong, C.-H.; Slowik, J. G.; Chang, R. Y.-W.; Corbin, J. C.; Lu, G.; Mihele, C.; Rehbein, P. J. G.; Sills, D. M. L.; Abbatt, J. P. D.; Brook, J. R.; Evans, G. J.

    2011-03-01

    An aerosol time-of-flight mass spectrometer (ATOFMS) was deployed at a semi-rural site in Southern Ontario to characterize the size and chemical composition of individual particles. Particle-type-based receptor modelling of these data was used to investigate the determinants of aerosol chemical composition in this region. Individual particles were classified into particle-types and positive matrix factorization (PMF) was applied to their temporal trends to separate and cross-apportion particle-types to factors. The extent of chemical processing for each factor was assessed by evaluating the internal and external mixing state of the characteristic particle-types. The nine factors identified helped to elucidate the coupled interactions of these determinants. Nitrate-laden dust was found to be the dominant type of locally emitted particles measured by ATOFMS. Several factors associated with aerosol transported to the site from intermediate local-to-regional distances were identified: the Organic factor was associated with a combustion source to the north-west; the ECOC Day factor was characterized by nearby local-to-regional carbonaceous emissions transported from the south-west during the daytime; and the Fireworks factor consisted of pyrotechnic particles from the Detroit region following holiday fireworks displays. Regional aerosol from farther emissions sources were reflected through three factors: two biomass burning factors and a highly chemically processed long range transport factor. The biomass burning factors were separated by PMF due to differences in chemical processing which were caused in part by the passage of two thunderstorm gust fronts with different air mass histories. The remaining two factors, ECOC Night and Nitrate Background, represented the night-time partitioning of nitrate to pre-existing particles of different origins. The distinct meteorological conditions observed during this month-long study in the summer of 2007 provided a unique range

  12. Elucidating determinants of aerosol composition through particle-type-based receptor modeling

    NASA Astrophysics Data System (ADS)

    McGuire, M. L.; Jeong, C.-H.; Slowik, J. G.; Chang, R. Y.-W.; Corbin, J. C.; Lu, G.; Mihele, C.; Rehbein, P. J. G.; Sills, D. M. L.; Abbatt, J. P. D.; Brook, J. R.; Evans, G. J.

    2011-08-01

    An aerosol time-of-flight mass spectrometer (ATOFMS) was deployed at a semi-rural site in southern Ontario to characterize the size and chemical composition of individual particles. Particle-type-based receptor modelling of these data was used to investigate the determinants of aerosol chemical composition in this region. Individual particles were classified into particle-types and positive matrix factorization (PMF) was applied to their temporal trends to separate and cross-apportion particle-types to factors. The extent of chemical processing for each factor was assessed by evaluating the internal and external mixing state of the characteristic particle-types. The nine factors identified helped to elucidate the coupled interactions of these determinants. Nitrate-laden dust was found to be the dominant type of locally emitted particles measured by ATOFMS. Several factors associated with aerosol transported to the site from intermediate local-to-regional distances were identified: the Organic factor was associated with a combustion source to the north-west; the ECOC Day factor was characterized by nearby local-to-regional carbonaceous emissions transported from the south-west during the daytime; and the Fireworks factor consisted of pyrotechnic particles from the Detroit region following holiday fireworks displays. Regional aerosol from farther emissions sources was reflected through three factors: two Biomass Burning factors and a highly chemically processed Long Range Transport factor. The Biomass Burning factors were separated by PMF due to differences in chemical processing which were in part elucidated by the passage of two thunderstorm gust fronts with different air mass histories. The remaining two factors, ECOC Night and Nitrate Background, represented the night-time partitioning of nitrate to pre-existing particles of different origins. The distinct meteorological conditions observed during this month-long study in the summer of 2007 provided a unique

  13. Chemical composition of individual aerosol particles from working areas in a nickel refinery.

    PubMed

    Höflich, B L; Wentzel, M; Ortner, H M; Weinbruch, S; Skogstad, A; Hetland, S; Thomassen, Y; Chaschin, V P; Nieboer, E

    2000-06-01

    Individual aerosol particles (n = 1170) collected at work stations in a nickel refinery were analyzed by wavelength-dispersive electron-probe microanalysis. By placing arbitrary restrictions on the contents of sulfur and silicon, the particles could be divided into four main groups. Scanning electron images indicated that most of the particles examined were relatively small (< or = 2 microm, equivalent projected area diameter), and that their morphology suggested formation from a melt. There was an absence of well-defined phases and simple stoichiometries, indicating that exposures to pure substances such as nickel subsulfide or specific oxides appeared not to occur. Although the elemental composition of particles varied greatly, a rough association was evident with the known elemental content of the refinery intermediates. The implications of the findings for aerosol speciation measurements, toxicological studies and interpretation of adverse health effects are explored. PMID:11256701

  14. Heterogeneous Reactivity of Nitric Acid with Nascent Sea Spray Aerosol: Large Differences Observed between and within Individual Particles.

    PubMed

    Ault, Andrew P; Guasco, Timothy L; Baltrusaitis, Jonas; Ryder, Olivia S; Trueblood, Jonathan V; Collins, Douglas B; Ruppel, Matthew J; Cuadra-Rodriguez, Luis A; Prather, Kimberly A; Grassian, Vicki H

    2014-08-01

    Current climate and atmospheric chemistry models assume that all sea spray particles react as if they are pure NaCl. However, recent studies of sea spray aerosol particles have shown that distinct particle types exist (including sea salt, organic carbon, and biological particles) as well as mixtures of these and, within each particle type, there is a range of single-particle chemical compositions. Because of these differences, individual particles should display a range of reactivities with trace atmospheric gases. Herein, to address this, we study the composition of individual sea spray aerosol particles after heterogeneous reaction with nitric acid. As expected, a replacement reaction of chloride with nitrate is observed; however, there is a large range of reactivities spanning from no reaction to complete reaction between and within individual sea spray aerosol particles. These data clearly support the need for laboratory studies of individual, environmentally relevant particles to improve our fundamental understanding as to the properties that determine reactivity.

  15. Aerosols in Amazonia: Natural biogenic particles and large scale biomass burning impacts

    NASA Astrophysics Data System (ADS)

    Artaxo, Paulo; Barbosa, Henrique M. J.; Rizzo, Luciana V.; Brito, Joel F.; Sena, Elisa T.; Cirino, Glauber G.; Arana, Andrea

    2013-05-01

    The Large Scale Biosphere Atmosphere Experiment in Amazonia (LBA) is a long term (20 years) research effort aimed at the understanding of the functioning of the Amazonian ecosystem. In particular, the strong biosphere-atmosphere interaction is a key component looking at the exchange processes between vegetation and the atmosphere, focusing on aerosol particles. Two aerosol components are the most visible: The natural biogenic emissions of aerosols and VOCs, and the biomass burning emissions. A large effort was done to characterize natural biogenic aerosols that showed detailed organic characterization and optical properties. The biomass burning component in Amazonia is important in term of aerosol and trace gases emissions, with deforestation rates decreasing, from 27,000 Km2 in 2004 to about 5,000 Km2 in 2011. Biomass burning emissions in Amazonia increases concentrations of aerosol particles, CO, ozone and other species, and also change the surface radiation balance in a significant way. Long term monitoring of aerosols and trace gases were performed in two sites: a background site in Central Amazonia, 55 Km North of Manaus (called ZF2 ecological reservation) and a monitoring station in Porto Velho, Rondonia state, a site heavily impacted by biomass burning smoke. Several instruments were operated to measured aerosol size distribution, optical properties (absorption and scattering at several wavelengths), composition of organic (OC/EC) and inorganic components among other measurements. AERONET and MODIS measurements from 5 long term sites show a large year-to year variability due to climatic and socio-economic issues. Aerosol optical depths of more than 4 at 550nm was observed frequently over biomass burning areas. In the pristine Amazonian atmosphere, aerosol scattering coefficients ranged between 1 and 200 Mm-1 at 450 nm, while absorption ranged between 1 and 20 Mm-1 at 637 nm. A strong seasonal behavior was observed, with greater aerosol loadings during the

  16. Multiple new-particle growth pathways observed at the US DOE Southern Great Plains field site

    DOE PAGES

    Hodshire, Anna L.; Lawler, Michael J.; Zhao, Jun; Ortega, John; Jen, Coty; Yli-Juuti, Taina; Brewer, Jared F.; Kodros, Jack K.; Barsanti, Kelley C.; Hanson, Dave R.; et al

    2016-07-28

    New-particle formation (NPF) is a significant source of aerosol particles into the atmosphere. However, these particles are initially too small to have climatic importance and must grow, primarily through net uptake of low-volatility species, from diameters  ∼  1 to 30–100 nm in order to potentially impact climate. There are currently uncertainties in the physical and chemical processes associated with the growth of these freshly formed particles that lead to uncertainties in aerosol-climate modeling. Four main pathways for new-particle growth have been identified: condensation of sulfuric-acid vapor (and associated bases when available), condensation of organic vapors, uptake of organic acids through acid–base chemistrymore » in the particle phase, and accretion of organic molecules in the particle phase to create a lower-volatility compound that then contributes to the aerosol mass. The relative importance of each pathway is uncertain and is the focus of this work. The 2013 New Particle Formation Study (NPFS) measurement campaign took place at the DOE Southern Great Plains (SGP) facility in Lamont, Oklahoma, during spring 2013. Measured gas- and particle-phase compositions during these new-particle growth events suggest three distinct growth pathways: (1) growth by primarily organics, (2) growth by primarily sulfuric acid and ammonia, and (3) growth by primarily sulfuric acid and associated bases and organics. To supplement the measurements, we used the particle growth model MABNAG (Model for Acid–Base chemistry in NAnoparticle Growth) to gain further insight into the growth processes on these 3 days at SGP. MABNAG simulates growth from (1) sulfuric-acid condensation (and subsequent salt formation with ammonia or amines), (2) near-irreversible condensation from nonreactive extremely low-volatility organic compounds (ELVOCs), and (3) organic-acid condensation and subsequent salt formation with ammonia or amines. MABNAG is able to corroborate the

  17. Real-Time Characterization of Aerosol Particle Composition above the Urban Canopy in Beijing: Insights into the Interactions between the Atmospheric Boundary Layer and Aerosol Chemistry.

    PubMed

    Sun, Yele; Du, Wei; Wang, Qingqing; Zhang, Qi; Chen, Chen; Chen, Yong; Chen, Zhenyi; Fu, Pingqing; Wang, Zifa; Gao, Zhiqiu; Worsnop, Douglas R

    2015-10-01

    Despite extensive efforts into the characterization of air pollution during the past decade, real-time characterization of aerosol particle composition above the urban canopy in the megacity Beijing has never been performed to date. Here we conducted the first simultaneous real-time measurements of aerosol composition at two different heights at the same location in urban Beijing from December 19, 2013 to January 2, 2014. The nonrefractory submicron aerosol (NR-PM1) species were measured in situ by a high-resolution aerosol mass spectrometer at near-ground level and an aerosol chemical speciation monitor at 260 m on a 325 m meteorological tower in Beijing. Secondary aerosol showed similar temporal variations between ground level and 260 m, whereas much weaker correlations were found for the primary aerosol. The diurnal evolution of the ratios and correlations of aerosol species between 260 m and the ground level further illustrated a complex interaction between vertical mixing processes and local source emissions on aerosol chemistry in the atmospheric boundary layer. As a result, the aerosol compositions at the two heights were substantially different. Organic aerosol (OA), mainly composed of primary OA (62%), at the ground level showed a higher contribution to NR-PM1 (65%) than at 260 m (54%), whereas a higher concentration and contribution (15%) of nitrate was observed at 260 m, probably due to the favorable gas-particle partitioning under lower temperature conditions. In addition, two different boundary layer structures were observed, each interacting differently with the evolution processes of aerosol chemistry.

  18. Real-Time Characterization of Aerosol Particle Composition above the Urban Canopy in Beijing: Insights into the Interactions between the Atmospheric Boundary Layer and Aerosol Chemistry.

    PubMed

    Sun, Yele; Du, Wei; Wang, Qingqing; Zhang, Qi; Chen, Chen; Chen, Yong; Chen, Zhenyi; Fu, Pingqing; Wang, Zifa; Gao, Zhiqiu; Worsnop, Douglas R

    2015-10-01

    Despite extensive efforts into the characterization of air pollution during the past decade, real-time characterization of aerosol particle composition above the urban canopy in the megacity Beijing has never been performed to date. Here we conducted the first simultaneous real-time measurements of aerosol composition at two different heights at the same location in urban Beijing from December 19, 2013 to January 2, 2014. The nonrefractory submicron aerosol (NR-PM1) species were measured in situ by a high-resolution aerosol mass spectrometer at near-ground level and an aerosol chemical speciation monitor at 260 m on a 325 m meteorological tower in Beijing. Secondary aerosol showed similar temporal variations between ground level and 260 m, whereas much weaker correlations were found for the primary aerosol. The diurnal evolution of the ratios and correlations of aerosol species between 260 m and the ground level further illustrated a complex interaction between vertical mixing processes and local source emissions on aerosol chemistry in the atmospheric boundary layer. As a result, the aerosol compositions at the two heights were substantially different. Organic aerosol (OA), mainly composed of primary OA (62%), at the ground level showed a higher contribution to NR-PM1 (65%) than at 260 m (54%), whereas a higher concentration and contribution (15%) of nitrate was observed at 260 m, probably due to the favorable gas-particle partitioning under lower temperature conditions. In addition, two different boundary layer structures were observed, each interacting differently with the evolution processes of aerosol chemistry. PMID:26348650

  19. Pulse height response of an optical particle counter to monodisperse aerosols

    NASA Technical Reports Server (NTRS)

    Wilmoth, R. G.; Grice, S. S.; Cuda, V.

    1976-01-01

    The pulse height response of a right angle scattering optical particle counter has been investigated using monodisperse aerosols of polystyrene latex spheres, di-octyl phthalate and methylene blue. The results confirm previous measurements for the variation of mean pulse height as a function of particle diameter and show good agreement with the relative response predicted by Mie scattering theory. Measured cumulative pulse height distributions were found to fit reasonably well to a log normal distribution with a minimum geometric standard deviation of about 1.4 for particle diameters greater than about 2 micrometers. The geometric standard deviation was found to increase significantly with decreasing particle diameter.

  20. An experimental study of growth and phase change of polar stratospheric cloud particles

    NASA Technical Reports Server (NTRS)

    Hallett, John; Teets, Edward

    1992-01-01

    This report describes the progress made on understanding phase changes related to solutions which may comprise Polar Stratospheric Clouds. In particular, it is concerned with techniques for investigating specific classes of metastability and phase change which may be important not only in Polar Stratospheric Clouds but in all atmospheric aerosols in general. While the lower level atmospheric aerosol consists of mixtures of (NH4)(SO4)2, NH4HSO4, NaCl among others, there is evidence that aerosol at PSC levels is composed of acid aerosol, either injected from volcanic events (such as Pinatubo) or having diffused upward from the lower atmosphere. In particular, sulfuric acid and nitric acid are known to occur at PSC levels, and are suspected of catalyzing ozone destruction reactions by adsorption on surfaces of crystallized particles. The present study has centered on two approaches: (1) the extent of supercooling (with respect to ice) and supersaturation (with respect to hydrate) and the nature of crystal growth in acid solutions of specific molality; and (2) the nature of growth from the vapor of HNO3 - H2O crystals both on a substrate and on a pre-existing aerosol.

  1. Deposition of aerosol particles in human lungs: in vivo measurements and modeling

    EPA Science Inventory

    The deposition dose and site of inhaled particles within the lung are the key determinants in health risk assessment of particulate pollutants. Accurate dose estimation, however, is a formidable task because aerosol transport and deposition in the lung are governed by many factor...

  2. USE OF CONTINUOUS MEASUREMENTS OF INTEGRAL AEROSOL PARAMETERS TO ESTIMATE PARTICLE SURFACE AREA

    EPA Science Inventory

    This study was undertaken because of interest in using particle surface area as an indicator for studies of the health effects of particulate matter. First, we wished to determine the integral parameter of the size distribution measured by the electrical aerosol detector. Secon...

  3. Measurement of Fluorescence Spectra from Ambient Aerosol Particles Using Laser-induced Fluorescence Technique

    NASA Astrophysics Data System (ADS)

    Taketani, F.; Kanaya, Y.; Nakamura, T.; Moteki, N.; Takegawa, N.

    2011-12-01

    To obtain the information of composition of organic aerosol particles in atmosphere, we developed an instrument using laser-induced fluorescence (LIF) technique. To measure the fluorescence from a particle, we employed two lasers. Scattering light signal derived from a single particle upon crossing the 635nm-CW laser triggers the 266nm-pulsed laser to excite the particle. Fluorescence from the particle in the wavelength range 300-600nm is spectrally dispersed by a grating spectrometer and then detected by a 32-Ch photo-multiplier tube(PMT). The aerosol stream is surrounded by a coaxial sheath air flow and delivered to the optical chamber at atmospheric pressure. Using PSL particles with known sizes, we made a calibration curve to estimate particle size from scattering light intensity. With the current setup of the instrument we are able to detect both scattering and fluorescence from particles whose diameters are larger than 0.5um. Our system was able to differentiate particles composed of mono-aromatic species (e.g. Tryptophan) from those of Riboflavin, by their different fluorescence wavelengths. Also, measurements of fluorescence spectra of ambient particles were demonstrated in our campus in Yokosuka city, facing Tokyo bay in Japan. We obtained several types of florescence spectra in the 8 hours. Classification of the measured fluorescence spectra will be discussed in the presentation.

  4. The Composition of Individual Aerosol Particles over the North Slope of Alaska during ISDAC

    NASA Astrophysics Data System (ADS)

    Zelenyuk, A.; Imre, D.; Liu, P.; MacDonald, A.; Leaitch, R.

    2008-12-01

    During the month of April 2008 a single particle mass spectrometer, SPLAT II, was deployed on board the Canadian National Research Council Convair 580 aircraft for participation in the Indirect and Semi-Direct Aerosol Campaign (ISDAC). ISDAC's main scientific objective was to improve our understanding of the relationship between the properties of aerosol particles over the North Pole and their impact on the regional climate. During ISDAC SPLAT II participated in all 27 flights that lasted slightly over 100 hrs. It measured the size of more than 10 million particles and characterized the composition of over 3 million of them. When sampling in clear air SPLAT II measured a wide range of particle compositions, including sulfates mixed with organics, nitrates mixed with organic, processed and freshly emitted sea-salt, a few dust particles, and a significant number of biomass burning particles. Many of these particle types appeared in aerosol layers that had horizontal and vertical filamentous structures. Biomass burning particles, many of which were transported from Asia, were rather prevalent over the North Slope of Alaska during the campaign. Since one of the main goals of this campaign was to characterize cloud properties, large fraction of the data was collected through the CVI inlet. The ice-clouds sampled in ISDAC had typically very low ice crystal concentrations; correspondingly, when sampled through the CVI inlet the number of characterized particles drops precipitously. Despite the low number concentrations SPLAT was able to measure the size and composition of thousands of ice-nuclei. Since the CVI inlet transmits, in addition to ice crystals, liquid droplets, SPLAT was able to characterize a large number of particles that served as cloud condensation nuclei as well. We will present a preliminary analysis of the single particle data collected during this campaign.

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

    NASA Astrophysics Data System (ADS)

    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 < Dp < 50 nm) to total particles was recorded also in winter and was attributed partly to the effect of local heating. Furthermore, back trajectories (HYSPLIT model) showed that different air mass origins are linked to different levels of particle number concentrations, with higher values associated with air masses passing from polluted areas before reaching the Akrotiri station. Modal analysis of the measured size distribution data revealed a strong nucleation mode during winter (15-25 nm), which can be correlated with emissions from local sources (domestic heating). The nucleation mode was observed also during the spring campaigns and was partly linked to new particle formation events. On the contrary, an accumulation mode (80-120 nm) prevailed in the measurements during summer campaigns, when the station area was influenced by polluted air masses arriving mainly from Eastern Europe. In total, 13 new particle formation events were recorded

  6. The effect of acid-base clustering and ions on the growth of atmospheric nano-particles

    NASA Astrophysics Data System (ADS)

    Lehtipalo, Katrianne; Rondo, Linda; Kontkanen, Jenni; Schobesberger, Siegfried; Jokinen, Tuija; Sarnela, Nina; Kürten, Andreas; Ehrhart, Sebastian; Franchin, Alessandro; Nieminen, Tuomo; Riccobono, Francesco; Sipilä, Mikko; Yli-Juuti, Taina; Duplissy, Jonathan; Adamov, Alexey; Ahlm, Lars; Almeida, João; Amorim, Antonio; Bianchi, Federico; Breitenlechner, Martin; Dommen, Josef; Downard, Andrew J.; Dunne, Eimear M.; Flagan, Richard C.; Guida, Roberto; Hakala, Jani; Hansel, Armin; Jud, Werner; Kangasluoma, Juha; Kerminen, Veli-Matti; Keskinen, Helmi; Kim, Jaeseok; Kirkby, Jasper; Kupc, Agnieszka; Kupiainen-Määttä, Oona; Laaksonen, Ari; Lawler, Michael J.; Leiminger, Markus; Mathot, Serge; Olenius, Tinja; Ortega, Ismael K.; Onnela, Antti; Petäjä, Tuukka; Praplan, Arnaud; Rissanen, Matti P.; Ruuskanen, Taina; Santos, Filipe D.; Schallhart, Simon; Schnitzhofer, Ralf; Simon, Mario; Smith, James N.; Tröstl, Jasmin; Tsagkogeorgas, Georgios; Tomé, António; Vaattovaara, Petri; Vehkamäki, Hanna; Vrtala, Aron E.; Wagner, Paul E.; Williamson, Christina; Wimmer, Daniela; Winkler, Paul M.; Virtanen, Annele; Donahue, Neil M.; Carslaw, Kenneth S.; Baltensperger, Urs; Riipinen, Ilona; Curtius, Joachim; Worsnop, Douglas R.; Kulmala, Markku

    2016-05-01

    The growth of freshly formed aerosol particles can be the bottleneck in their survival to cloud condensation nuclei. It is therefore crucial to understand how particles grow in the atmosphere. Insufficient experimental data has impeded a profound understanding of nano-particle growth under atmospheric conditions. Here we study nano-particle growth in the CLOUD (Cosmics Leaving OUtdoors Droplets) chamber, starting from the formation of molecular clusters. We present measured growth rates at sub-3 nm sizes with different atmospherically relevant concentrations of sulphuric acid, water, ammonia and dimethylamine. We find that atmospheric ions and small acid-base clusters, which are not generally accounted for in the measurement of sulphuric acid vapour, can participate in the growth process, leading to enhanced growth rates. The availability of compounds capable of stabilizing sulphuric acid clusters governs the magnitude of these effects and thus the exact growth mechanism. We bring these observations into a coherent framework and discuss their significance in the atmosphere.

  7. Suppression in droplet growth kinetics by the addition of organics to sulfate particles

    NASA Astrophysics Data System (ADS)

    Wong, Jenny P. S.; Liggio, John; Li, Shao-Meng; Nenes, Athanasios; Abbatt, Jonathan P. D.

    2014-11-01

    Aerosol-cloud interactions are affected by the rate at which water vapor condenses onto particles during cloud droplet growth. Changes in droplet growth rates can impact cloud droplet number and size distribution. The current study investigated droplet growth kinetics of acidic and neutral sulfate particles which contained various amounts and types of organic compounds, from model compounds (carbonyls) to complex mixtures (α-pinene secondary organic aerosol and diesel engine exhaust). In most cases, the formed droplet size distributions were shifted to smaller sizes relative to control experiments (pure sulfate particles), due to suppression in droplet growth rates in the cloud condensation nuclei counter. The shift to smaller droplets correlated with increasing amounts of organic material, with the largest effect observed for acidic seed particles at low relative humidity. For all organics incorporated onto acidic particles, formation of high molecular weight compounds was observed, probably by acid-catalyzed Aldol condensation reactions in the case of carbonyls. To test the reversibility of this process, carbonyl experiments were conducted with acidic particles exposed to higher relative humidity. High molecular weight compounds were not measured in this case and no shift in droplet sizes was observed, suggesting that high molecular weight compounds are the species affecting the rate of water uptake. While these results provide laboratory evidence that organic compounds can slow droplet growth rates, the modeled mass accommodation coefficient of water on these particles (α > 0.1) indicates that this effect is unlikely to significantly affect cloud properties, consistent with infrequent field observations of slower droplet growth rates.

  8. Mass concentration and mineralogical characteristics of aerosol particles collected at Dunhuang during ACE-Asia

    NASA Astrophysics Data System (ADS)

    Shen, Z. X.; Cao, J. J.; Li, X. X.; Okuda, T.; Wang, Y. Q.; Zhang, X. Y.

    2006-03-01

    Measurements were performed in spring 2001 and 2002 to determine the characteristics of soil dust in the Chinese desert region of Dunhuang, one of the ground sites of the Asia-Pacific Regional Aerosol Characterization Experiment (ACE-Asia). The mean mass concentrations of total suspended particle matter during the spring of 2001 and 2002 were 317 mu g m(-3) and 307 mu g m(-3) respectively. Eleven dust storm events were observed with a mean aerosol concentration of 1095 mu g m(-3), while the non-dusty days with calm or weak wind speed had a background aerosol loading of 196 mu g m(-3) on average in the springtime. The main minerals detected in the aerosol samples by X-ray diffraction were illite, kaolinite, chlorite, quartz, feldspar, calcite and dolomite. Gypsum, halite and amphibole were also detected in a few samples. The mineralogical data also show that Asian dust is characterized by a kaolinite to chlorite (K/C) ratio lower than 1 whereas Saharan dust exhibits a K/C ratio larger than 2. Air mass back- trajectory analysis show that three families of pathways are associated with the aerosol particle transport to Dunhuang, but these have similar K/C ratios, which further demonstrates that the mineralogical characteristics of Asian dust are different from African dust.

  9. An aircraft-based case study of new particle formation and growth in the summertime Arctic

    NASA Astrophysics Data System (ADS)

    Willis, M. D.; Abbatt, J.; Burkart, J.; Bozem, H.; Koellner, F.; Schneider, J.; Hoor, P. M.; Herber, A. B.; Leaitch, W. R.

    2015-12-01

    Motivated by the changing climate of the Arctic and decreasing summer sea-ice extent, we aim to better understand how atmospheric composition will impact, or be impacted by, climate and environmental change in this region. Much attention has been paid to springtime Arctic aerosol owing to significant anthropogenic influence on this remote environment, but the cleaner, more locally influenced summertime Arctic is not well characterized. We present results of vertically resolved, particle number, aerosol size distributions, submicron aerosol composition from an aerosol mass spectrometer (AMS), and cloud condensation nuclei (CCN) concentrations from the NETCARE 2014 Polar 6 aircraft campaign. The campaign was based in the high Arctic, at Resolute Bay, Nunavut, Canada (74°N, 94°W), allowing measurements from 60 to 2900 meters over ice, open water and near the ice-edge. The focus of this case study is a new particle formation and growth event observed at the eastern end of Lancaster Sound (74°N, 81°W) on July 12, 2014 under clear sky conditions. During this flight Polar 6 travelled to the end of Lancaster Sound at 2900 m and subsequently descended to 60-70 m above the surface heading due west, with winds from the west. At the lowest altitude we observed a significant increase in particles > 4 nm, between 20 - 100 nm, and > 100 nm, indicating the presence of small particles between 4 - 20 nm and growth to larger sizes. In addition, CCN concentrations were enhanced up to ~ 200/cm3 from background levels of ≤ 100/cm3. Concurrently, the AMS indicated enhanced levels of methane sulfonic acid (MSA) and marine-like organic aerosol (OA) correlated in time with the presence of larger particles, as well as an iodide signal which correlated with the presence of small particles. These observations suggest that iodine oxides could be one contributor to particle formation, and that marine-like OA and MSA could contribute to particle growth in the summertime Arctic.

  10. Relating the hygroscopic properties of submicron aerosol to both gas- and particle-phase chemical composition in a boreal forest environment

    NASA Astrophysics Data System (ADS)

    Hong, J.; Kim, J.; Nieminen, T.; Duplissy, J.; Ehn, M.; Äijälä, M.; Hao, L.; Nie, W.; Sarnela, N.; Prisle, N. L.; Kulmala, M.; Virtanen, A.; Petäjä, T.; Kerminen, V.-M.

    2015-06-01

    Measurements of the hygroscopicity of 15-145 nm particles in a boreal forest environment were conducted using two Hygroscopicity Tandem Differential Mobility Analyzer (HTDMA) systems during the Pan-European Gas-AeroSOIs-climate interaction Study (PEGASOS) campaign in spring 2013. Measurements of the chemical composition of non-size segregated particles were also performed using a High-Resolution Aerosol Mass Spectrometer (HR-AMS) in parallel with hygroscopicity measurements. On average, the hygroscopic growth factor (HGF) of particles was observed to increase from the morning until afternoon. In case of accumulation mode particles, the main reasons for this behavior were increases in the ratio of sulfate to organic matter and oxidation level (O : C ratio) of the organic matter in the particle phase. Using an O : C dependent hygroscopic growth factor of organic matter (HGForg), fitted using the inverse Zdanovskii-Stokes-Robinson (ZSR) mixing rule, clearly improved the agreement between measured HGF and that predicted based on HR-AMS composition data. Besides organic oxidation level, the influence of inorganic species was tested when using the ZSR mixing rule to estimate the hygroscopic growth factor of organics in the aerosols. While accumulation and Aitken mode particles were predicted fairly well by the bulk aerosol composition data, the hygroscopicity of nucleation mode particles showed little correlation. However, we observed them to be more sensitive to the gas phase concentration of condensable vapors: the more there was sulfuric acid in the gas phase, the more hygroscopic the nucleation mode particles were. No clear dependence was found between the extremely low-volatility organics (ELVOCs) concentration and the HGF of particles of any size.

  11. Ozone and secondary aerosol formation — Analysis of particle observations in the 2009 SHARP campaign

    NASA Astrophysics Data System (ADS)

    Cowin, J.; Yu, X.; Laulainen, N.; Iedema, M.; Lefer, B. L.; Anderson, D.; Pernia, D.; Flynn, J. H.

    2010-12-01

    Particulate matters (PM) play important roles in the formation and transformation of ozone. Although photooxidation of volatile organic compounds with respect to ozone formation in the gas phase is well understood, many unknowns still exist in heterogeneous mechanisms that process soot, secondary aerosols (both inorganic and organic), and key radical precursors such as formaldehyde and nitrous acid. Our main objective is to answer two key science questions: 1) will reduction of fine PM reduce ozone formation? 2) What sources of PM are most culpable? Are they from local chemistry or long-range transport? The field data collected in the 2009 Study of Houston Atmospheric Radical Precursors (SHARP) by our group at the Moody Tower consist of 1) real-time photolysis rates of ozone precursors, 2) particle size distributions, 3) organic carbon and elemental carbon, and 4) an archive of single particle samples taken with the Time Resolved Aerosol Collector (TRAC) sampler. The time resolution of the TRAC sampler is 30 minutes for routine measurements, and 15 minutes during some identified “events” (usually in the mid-afternoon) of high ozone and secondary organic or sulfate particle formation. The latter events last typically about an hour. Five ozone exceedance days occurred during the 6 weeks of deployment. Strong correlation between photochemical activities and organic carbon was observed. Initial data analysis indicates that secondary organic aerosol is a major component of the carbonaceous aerosols observed in Houston. Soot, secondary sulfate, seal salt, and mineral dust particles are determined from single particle analysis using scanning electron microscope and transmission electron microcopy coupled with energy dispersive X-ray spectroscopy. Compared with observations in 2000, the mass percentage of organics is higher (60 vs. 30%), and lower for sulfate (20% vs. 32%). On-going data analysis will focus on the composition, sources, and transformation of primary and

  12. Microscopy and Spectroscopy Techniques to Guide Parameters for Modeling Mineral Dust Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Veghte, D. P.; Moore, J. E.; Jensen, L.; Freedman, M. A.

    2013-12-01

    Mineral dust aerosol particles are the second largest emission by mass into the atmosphere and contribute to the largest uncertainty in radiative forcing. Due to the variation in size, composition, and shape, caused by physical and chemical processing, uncertainty exists as to whether mineral dust causes a net warming or cooling effect. We have used Cavity Ring-Down Aerosol Extinction Spectroscopy (CRD-AES), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM) to measure extinction cross sections and morphologies of size-selected, non-absorbing and absorbing mineral dust aerosol particles. We have found that microscopy is essential for characterizing the polydispersity of the size selection of non-spherical particles. Through the combined use of CRD-AES, microscopy, and computation (Mie theory and Discreet Dipole Approximation), we have determined the effect of shape on the optical properties of additional species including clay minerals, quartz, and hematite in the sub-micron regime. Our results have shown that calcite can be treated as polydisperse spheres while quartz and hematite need additional modeling parameters to account for their irregularity. Size selection of clay minerals cannot be performed due to their irregular shape, but microscopy techniques can be used to better quantify the particle aspect ratio. Our results demonstrate a new method that can be used to extend cavity ring-down spectroscopy for the measurement of the optical properties of non-spherical particles. This characterization will lead to better aerosol extinction parameters for modeling aerosol optical properties in climate models and satellite retrieval algorithms.

  13. Numerical Modeling of an RF Argon-Silane Plasma with Dust Particle Nucleation and Growth

    NASA Astrophysics Data System (ADS)

    Girshick, Steven; Agarwal, Pulkit

    2012-10-01

    We have developed a 1-D numerical model of an RF argon-silane plasma in which dust particles nucleate and grow. This model self-consistently couples a plasma module, a chemistry module and an aerosol module. The plasma module solves population balance equations for electrons and ions, the electron energy equation under the assumption of a Maxwellian velocity distribution, and Poisson's equation for the electric field. The chemistry module treats silane dissociation and reactions of silicon hydrides containing up to two silicon atoms. The aerosol module uses a sectional method to model particle size and charge distributions. The nucleation rate is equated to the rates of formation of anions containing two Si atoms, and a heterogeneous reaction model is used to model particle surface growth. Aerosol effects considered include particle charging, coagulation, and particle transport by neutral drag, ion drag, electric force, gravity and Brownian diffusion. Simulation results are shown for the case of a 13.56 MHz plasma at a pressure of 13 Pa and applied RF voltage of 100 V (amplitude), with flow through a showerhead electrode. These results show the strong coupling between the plasma and the spatiotemporal evolution of the nanoparticle cloud.

  14. Real-time measurement of sodium chloride in individual aerosol particles by mass spectrometry

    NASA Technical Reports Server (NTRS)

    Sinha, M. P.; Friedlander, S. K.

    1985-01-01

    The method of particle analysis by mass spectrometry has been applied to the quantitative measurement of sodium chloride in individual particles on a real-time basis. Particles of known masses are individually introduced, in the form of a beam, into a miniature Knudsen cell oven (1600 K). The oven is fabricated from rhenium metal sheet (0.018 mm thick) and is situated in the ion source of a quadrupole mass spectrometer. A particle once inside the oven is trapped and completely volatilized; this overcomes the problem of partial volatilization due to particles bouncing from the filament surface. Individual particles are thermally volatilized and ionized inside the rhenium oven, and produce discrete sodium ion pulses whose intensities are measured with the quadrupole mass spectrometer. An ion pulse width of several milliseconds (4-12 ms) is found for particles in the mass range 1.3 x 10 to the -13th to 5.4 x 10 to the -11th g. The sodium ion intensity is found to be proportional to the particle mass to the 0.86-power. The intensity distribution for monodisperse aerosol particles possesses a geometric standard deviation of 1.09, showing that the method can be used for the determination of the mass distribution function with good resolution in a polydisperse aerosol.

  15. Fractal morphology, imaging and mass spectrometry of single aerosol particles in flight.

    PubMed

    Loh, N D; Hampton, C Y; Martin, A V; Starodub, D; Sierra, R G; Barty, A; Aquila, A; Schulz, J; Lomb, L; Steinbrener, J; Shoeman, R L; Kassemeyer, S; Bostedt, C; Bozek, J; Epp, S W; Erk, B; Hartmann, R; Rolles, D; Rudenko, A; Rudek, B; Foucar, L; Kimmel, N; Weidenspointner, G; Hauser, G; Holl, P; Pedersoli, E; Liang, M; Hunter, M S; Hunter, M M; Gumprecht, L; Coppola, N; Wunderer, C; Graafsma, H; Maia, F R N C; Ekeberg, T; Hantke, M; Fleckenstein, H; Hirsemann, H; Nass, K; White, T A; Tobias, H J; Farquar, G R; Benner, W H; Hau-Riege, S P; Reich, C; Hartmann, A; Soltau, H; Marchesini, S; Bajt, S; Barthelmess, M; Bucksbaum, P; Hodgson, K O; Strüder, L; Ullrich, J; Frank, M; Schlichting, I; Chapman, H N; Bogan, M J

    2012-06-28

    The morphology of micrometre-size particulate matter is of critical importance in fields ranging from toxicology to climate science, yet these properties are surprisingly difficult to measure in the particles' native environment. Electron microscopy requires collection of particles on a substrate; visible light scattering provides insufficient resolution; and X-ray synchrotron studies have been limited to ensembles of particles. Here we demonstrate an in situ method for imaging individual sub-micrometre particles to nanometre resolution in their native environment, using intense, coherent X-ray pulses from the Linac Coherent Light Source free-electron laser. We introduced individual aerosol particles into the pulsed X-ray beam, which is sufficiently intense that diffraction from individual particles can be measured for morphological analysis. At the same time, ion fragments ejected from the beam were analysed using mass spectrometry, to determine the composition of single aerosol particles. Our results show the extent of internal dilation symmetry of individual soot particles subject to non-equilibrium aggregation, and the surprisingly large variability in their fractal dimensions. More broadly, our methods can be extended to resolve both static and dynamic morphology of general ensembles of disordered particles. Such general morphology has implications in topics such as solvent accessibilities in proteins, vibrational energy transfer by the hydrodynamic interaction of amino acids, and large-scale production of nanoscale structures by flame synthesis.

  16. Fractal morphology, imaging and mass spectrometry of single aerosol particles in flight.

    PubMed

    Loh, N D; Hampton, C Y; Martin, A V; Starodub, D; Sierra, R G; Barty, A; Aquila, A; Schulz, J; Lomb, L; Steinbrener, J; Shoeman, R L; Kassemeyer, S; Bostedt, C; Bozek, J; Epp, S W; Erk, B; Hartmann, R; Rolles, D; Rudenko, A; Rudek, B; Foucar, L; Kimmel, N; Weidenspointner, G; Hauser, G; Holl, P; Pedersoli, E; Liang, M; Hunter, M S; Hunter, M M; Gumprecht, L; Coppola, N; Wunderer, C; Graafsma, H; Maia, F R N C; Ekeberg, T; Hantke, M; Fleckenstein, H; Hirsemann, H; Nass, K; White, T A; Tobias, H J; Farquar, G R; Benner, W H; Hau-Riege, S P; Reich, C; Hartmann, A; Soltau, H; Marchesini, S; Bajt, S; Barthelmess, M; Bucksbaum, P; Hodgson, K O; Strüder, L; Ullrich, J; Frank, M; Schlichting, I; Chapman, H N; Bogan, M J

    2012-06-28

    The morphology of micrometre-size particulate matter is of critical importance in fields ranging from toxicology to climate science, yet these properties are surprisingly difficult to measure in the particles' native environment. Electron microscopy requires collection of particles on a substrate; visible light scattering provides insufficient resolution; and X-ray synchrotron studies have been limited to ensembles of particles. Here we demonstrate an in situ method for imaging individual sub-micrometre particles to nanometre resolution in their native environment, using intense, coherent X-ray pulses from the Linac Coherent Light Source free-electron laser. We introduced individual aerosol particles into the pulsed X-ray beam, which is sufficiently intense that diffraction from individual particles can be measured for morphological analysis. At the same time, ion fragments ejected from the beam were analysed using mass spectrometry, to determine the composition of single aerosol particles. Our results show the extent of internal dilation symmetry of individual soot particles subject to non-equilibrium aggregation, and the surprisingly large variability in their fractal dimensions. More broadly, our methods can be extended to resolve both static and dynamic morphology of general ensembles of disordered particles. Such general morphology has implications in topics such as solvent accessibilities in proteins, vibrational energy transfer by the hydrodynamic interaction of amino acids, and large-scale production of nanoscale structures by flame synthesis. PMID:22739316

  17. Single-particle light-scattering measurement: photochemical aerosols and atmospheric particulates.

    PubMed

    Phillips, D T; Wyatt, P J

    1972-09-01

    The use of single-particle light-scattering measurements to determine the origin of atmospheric hazes has been explored by measurement of laboratory aerosols, field samples, and computer analysis of the light-scattering data. The refractive index of measured spherical particles 800 nm to 1000 nm in diameter was determined within 2%. For particles of diameter less than 500 nm the measurement of absolute scattering intensity is required for complete analysis. Distinctive nonspherical and absorbing particles were observed both in automotive exhaust and atmospheric samples. Electrostatic suspension of atmospheric particulates is demonstrated to provide a practical approach to optical measurement of single particles. The technique may be used to calibrate optical particle counters or identify particles with unique shape or refractive index.

  18. The Effect of Particle Size on Iron Solubility in Atmospheric Aerosols

    NASA Astrophysics Data System (ADS)

    Marcotte, A. R.; Majestic, B. J.; Anbar, A. D.; Herckes, P.

    2012-12-01

    The long range transport of mineral dust aerosols, which contain approximately 3% iron by mass, results in an estimated 14-16 Tg of iron deposited into the oceans annually; however, only a small percentage of the deposited iron is soluble. In high-nutrient, low chlorophyll ocean regions iron solubility may limit phytoplankton primary productivity. Although the atmospheric transport processes of mineral dust aerosols have been well studied, the role of particle size has been given little attention. In this work, the effect of particle size on iron solubility in atmospheric aerosols is examined. Iron-containing minerals (illite, kaolinite, magnetite, goethite, red hematite, black hematite, and quartz) were separated into five size fractions (10-2.5, 2.5-1, 1-0.5, 0.5-0.25, and <0.25μm) and extracted into buffer solutions simulating environments in the transport of aerosol particles for 150 minutes. Particle size was confirmed by scanning electron microscopy (SEM). Soluble iron content of the extracted mineral solutions was determined by inductively coupled plasma-mass spectrometry (ICP-MS). Extracted mineral solutions were also analyzed for Fe(II) and Fe(III) content using a ferrozine/UV-VIS method. Preliminary results show that differences in solution composition are more important than differences in size. When extracted into acetate and cloudwater buffers (pH 4.25-4.3), < 0.3% of the Fe in iron oxides (hematite, magnetite, and goethite) is transferred to solution as compared to ~0.1-35% for clays (kaolinite and illite). When extracted into a marine aerosol solution (pH 1.7), the percentage of Fe of the iron oxides and clays transferred to solution increases to approximately 0.5-3% and 5-70%, respectively. However, there is a trend of increased %Fe in the minerals transferred to solution in the largest and smallest size fractions (~0.01-0.3% and ~0.5-35% for iron oxides and clays, respectively), and decreased %Fe in the minerals transferred to solution in the mid

  19. Surface tensions, viscosities, and diffusion constants in mixed component single aerosol particles

    NASA Astrophysics Data System (ADS)

    Bzdek, Bryan; Marshall, Frances; Song, Young-Chul; Haddrell, Allen; Reid, Jonathan

    2016-04-01

    Surface tension and viscosity are important aerosol properties but are challenging to measure on individual particles owing to their small size and mass. Aerosol viscosity impacts semivolatile partitioning from the aerosol phase, molecular diffusion in the bulk of the particle, and reaction kinetics. Aerosol surface tension impacts how particles activate to serve as cloud condensation nuclei. Knowledge of these properties and how they change under different conditions hinders accurate modelling of aerosol physical state and atmospheric impacts. We present measurements made using holographic optical tweezers to directly determine the viscosity and surface tension of optically trapped droplets containing ~1-4 picolitres of material (corresponding to radii of ~5-10 micrometres). Two droplets are captured in the experimental setup, equilibrated to a relative humidity, and coalesced through manipulation of the relative trap positions. The moment of coalescence is captured using camera imaging as well as from elastically backscattered light connected to an oscilloscope. For lower viscosity droplets, the relaxation in droplet shape to a sphere follows the form of a damped oscillator and gives the surface tension and viscosity. For high viscosity droplets, the relaxation results in a slow merging of the two droplets to form a sphere and the timescale of that process permits determination of viscosity. We show that droplet viscosity and surface tension can be quantitatively determined to within <10% of the expected value for low viscosity droplets and to better than 1 order of magnitude for high viscosity droplets. Examples illustrating how properties such as surface tension can change in response to environmental conditions will be discussed. Finally, a study of the relationship between viscosity, diffusion constants, vapour pressures, and reactive uptake coefficients for a mixed component aerosol undergoing oxidation and volatilisation will be discussed.

  20. An Experimental Study of Atmospheric Homogeneous Nucleation: Cluster Growth and Gas-Particle Reactions of H2SO4

    NASA Technical Reports Server (NTRS)

    Eisele, F. L.

    1996-01-01

    The work proposed on this project included both field and laboratory studies. The laboratory studies were to consist of measurements of H2SO4 uptake and evaporation from aerosols of varying chemical composition, while the field component would include measurements of H2SO4 and other compounds which would be conducted as part of a large field campaign. By chance, the opportunity to conduct such an H2SO4/aerosol/ultrafine particle study in conjunction with an OH intercomparison/photochemistry study became available very early in this project (September 1993). This study was conducted at Caribou, Colorado in conjunction with several other groups from NCAR, NOAA and a number of universities. Our group measured OH, H2SO4, SO2, and H20, while Dr. McMurfy's group measured ultrafine particles, and total particle number and size distribution. In addition measurements of HO2/RO2, O3, NO, NO2, NO(y) CO, hydrocarbons, CH2O, and other chemical compounds and meteorological parameters were performed by the other participants and a new laser oblation/mass spectrometry technique was also employed by the NOAA Aeronomy Laboratory to study aerosol composition. The study of aerosol production and growth in conjunction with photochemical measurements is highly advantageous because particle growth precursors such as H2SO4.or MSA are formed by OH initiated sulfur oxidation. The large number of hydrocarbon measurements included in this study were also important in understanding particle growth.

  1. Hazardous particle binder, coagulant and re-aerosolization inhibitor

    DOEpatents

    Krauter, Paula; Zalk, David; Hoffman, D. Mark

    2011-04-12

    A copolymer and water/ethanol solvent solution capable of binding with airborne contaminants or potential airborne contaminants, such as biological weapon agents or toxic particulates, coagulating as the solvent evaporates, and adhering the contaminants to a surface so as to inhibit the re-suspension of such contaminants. The solution uses a water or ethanol/water mixture for the solvent, and a copolymer having one of several functional group sets so as to have physical and chemical characteristics of high adhesion, low viscosity, low surface tension, negative electrostatic charge, substantially neutral pH, and a low pKa. Use of the copolymer solution prevents re-aerosolization and transport of unwanted, reactive species thus increasing health and safety for personnel charged with decontamination of contaminated buildings and areas.

  2. Hazardous particle binder, coagulant and re-aerosolization inhibitor

    DOEpatents

    Krauter, Paula; Zalk, David; Hoffman, D. Mark

    2012-07-10

    A copolymer and water/ethanol solvent solution capable of binding with airborne contaminants or potential airborne contaminants, such as biological weapon agents or toxic particulates, coagulating as the solvent evaporates, and adhering the contaminants to a surface so as to inhibit the re-suspension of such contaminants. The solution uses a water or ethanol/water mixture for the solvent, and a copolymer having one of several functional group sets so as to have physical and chemical characteristics of high adhesion, low viscosity, low surface tension, negative electrostatic charge, substantially neutral pH, and a low pKa. Use of the copolymer solution prevents re-aerosolization and transport of unwanted, reactive species thus increasing health and safety for personnel charged with decontamination of contaminated buildings and areas.

  3. Gas-particle partitioning of semivolatile organic compounds (SOCs) on mixtures of aerosols in a smog chamber.

    PubMed

    Chandramouli, Bharadwaj; Jang, Myoseon; Kamens, Richard M

    2003-09-15

    The partitioning behavior of a set of diverse SOCs on two and three component mixtures of aerosols from different sources was studied using smog chamber experimental data. A set of SOCs of different compound types was introduced into a system containing a mixture of aerosols from two or more sources. Gas and particle samples were taken using a filter-filter-denuder sampling system, and a partitioning coefficient Kp was estimated using Kp = Cp/(CgTSP). Particle size distributions were measured using a differential mobility analyzer and a light scattering detector. Gas and particle samples were analyzed using GCMS. The aerosol composition in the chamber was tracked chemically using a combination of signature compounds and the organic matter mass fraction (f(om)) of the individual aerosol sources. The physical nature of the aerosol mixture in the chamber was determined using particle size distributions, and an aggregate Kp was estimated from theoretically calculated Kp on the individual sources. Model fits for Kp showed that when the mixture involved primary sources of aerosol, the aggregate Kp of the mixture could be successfully modeled as an external mixture of the Kp on the individual aerosols. There were significant differences observed for some SOCs between modeling the system as an external and as an internal mixture. However, when one of the aerosol sources was secondary, the aggregate model Kp required incorporation of the secondary aerosol products on the preexisting aerosol for adequate model fits. Modeling such a system as an external mixture grossly overpredicted the Kp of alkanes in the mixture. Indirect evidence of heterogeneous, acid-catalyzed reactions in the particle phase was also seen, leading to a significant increase in the polarity of the resulting aerosol mix and a resulting decrease in the observed Kp of alkanes in the chamber. The model was partly consistent with this decrease but could not completely explain the reduction in Kp because of

  4. Single-Particle Black Carbon Aerosol Verticle Profiles From the Boundary Layer to the Lower Stratosphere

    NASA Astrophysics Data System (ADS)

    Schwarz, J. P.; Gao, R. S.; Fahey, D. W.; Laurel, W. A.; Thomson, D. S.; Kok, G. L.; Baumgardner, D.; Wilson, J. C.; Lopez, J.; Aikin, K.; Jost, H.; Thompson, T. L.; Reeves, J. M.; Lowenstein, M.

    2005-12-01

    A sing