Science.gov

Sample records for aerosol particle composition

  1. 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.

  2. 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

  3. Individual aerosol particles from biomass burning in southern Africa: 2, Compositions and aging of inorganic particles

    NASA Astrophysics Data System (ADS)

    Li, Jia; Pósfai, MiháLy; Hobbs, Peter V.; Buseck, Peter R.

    2003-07-01

    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.

  4. 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

  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. Real-time characterization of the size and chemical composition of individual particles in ambient aerosol systems in Riverside, California

    SciTech Connect

    Noble, C.A.; Prather, K.A.

    1995-12-31

    Atmospheric aerosols, although ubiquitous, are highly diverse and continually fluctuating systems. A typical aerosol system may consist of particles with diameters between {approximately}0.002 {mu}m and {approximately}200 {mu}m. Even in rural or pristine areas, atmospheric particle concentration is significant, with concentrations up to 10{sup 8} particles/cm{sup 3} not being uncommon. Chemical composition of atmospheric particles vary from simple water droplets or acidic ices to soot particles and cigarette smoke. Due to changes in atmospheric conditions, processes such as nucleation, coagulation or heterogeneous chemistry may effect both physical and chemical properties of individual particles over relatively short time intervals. Recently, aerosol measurement techniques are focusing on determining the size and/or chemical composition of individual aerosol particles. This research group has recently developed aerosol time-of-flight mass spectrometry (ATOFMS), a technique which allows for real-time determination of the size and chemical composition of individual aerosol particles. Single particle measurements are performed in one instrument using dual laser aerodynamic particle sizing and time-of-flight mass spectrometry. Aerosol-time-of-flight mass spectrometry is briefly described in several other abstracts in this publication.

  7. 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

  8. 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.

  9. Individual aerosol particles from biomass burning in southern Africa: 1. Compositions and size distributions of carbonaceous particles

    NASA Astrophysics Data System (ADS)

    Pósfai, MiháLy; Simonics, RenáTa; Li, Jia; Hobbs, Peter V.; Buseck, Peter R.

    2003-07-01

    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.

  10. Aerosol processing of fine Ag:(Bi,Pb)2223 composite particles

    NASA Astrophysics Data System (ADS)

    Mancic, Lidija; Marinkovic, Bojan; Vulic, Predrag; Milosevic, Olivera

    2004-08-01

    This paper represents an attempt in the obtaining of metal-ceramic composite precursor powders in the Ag:Bi-based superconductor system with uniform distribution of comprised phases through spray pyrolysis method. The process involves aerosol formation ultrasonically (800 kHz) from the urea-modified nitrates precursor solution (for the fixed cation ratio Bi:Pb:Sr:Ca:Cu=1.8:0.2:2:2:3 and for the Ag fraction of 20 wt.%) and control over the aerosol decomposition united with self-combustion of droplets in a high-temperature tubular flow reactor in the temperature range up to 820 °C. Following the initial attempts in providing of the 2223 phase high contents, particles were additionally calcined for 2 h in air and oxygen, at 825 and 810 °C respectively. Structure, morphology and compositional stoichiometry of synthesized powders were followed in accordance to various analysis methods (XRD, DTA, SEM and EDS).

  11. Composition of Stratospheric Aerosol Particles collected during the SOLVE campaign 2000

    NASA Astrophysics Data System (ADS)

    Schütze, Katharina; Nathalie, Benker; Martin, Ebert; Ralf, Weigel; Wilson James, C.; Stephan, Borrmann; Stephan, Weinbruch

    2016-04-01

    Stratospheric Aerosol particles were collected during the SAGE III Ozone loss and validation Experiment (SOLVE) in January-March 2000 in Kiruna/ Sweden onboard the scientific ER-2 aircraft with the Multi-Sample Aerosol Collection System. The particles are deposited on Cu transmission electron microscopy (TEM) grids. Particles of six samples from different flights (including one PSC sample) were analyzed by TEM and Energy Dispersive X-ray detection (EDX) regarding their size, chemical composition and morphology. Most particles are sulfates (formed from droplets of sulfuric acid) which are not resistant to the electron beam. In addition, refractory particles in the size range of 100-500 nm are found. They are either embedded in the sulfates or occur as single particles. The refractory particles are mainly carbonaceous showing only C and O as major peaks in their X-ray spectra. Some particles contain minor amounts of Si and Fe. Both, the O/C (median from 0.10-0.40), as well as Si/C (median from 0.05-0.32) ratios are increasing with time, from the middle of January to the end of February. The largest Fe/C ratio (median: 0.37) is found in a sample of the end of January. Based on the nanostructure and the absence of potassium as a tracer, biomass burning can be excluded as a source. Soot from diesel engines as well as from aircrafts show a nanostructure which is not found in the refractory particles. Due to the fact that large volcanic eruptions, which introduced material directly into the stratosphere, were missing since the eruption of Mt. Pinatubo in 1991, they are a very unlikely source of the refractory particles. The most likely source of the refractory particles is thus extraterrestrial material.

  12. Chemical compositions of black carbon particle cores and coatings via soot particle aerosol mass spectrometry with photoionization and electron ionization.

    PubMed

    Canagaratna, Manjula R; Massoli, Paola; Browne, Eleanor C; Franklin, Jonathan P; Wilson, Kevin R; Onasch, Timothy B; Kirchstetter, Thomas W; Fortner, Edward C; Kolb, Charles E; Jayne, John T; Kroll, Jesse H; Worsnop, Douglas R

    2015-05-14

    Black carbon is an important constituent of atmospheric aerosol particle matter (PM) with significant effects on the global radiation budget and on human health. The soot particle aerosol mass spectrometer (SP-AMS) has been developed and deployed for real-time ambient measurements of refractory carbon particles. In the SP-AMS, black carbon or metallic particles are vaporized through absorption of 1064 nm light from a CW Nd:YAG laser. This scheme allows for continuous "soft" vaporization of both core and coating materials. The main focus of this work is to characterize the extent to which this vaporization scheme provides enhanced chemical composition information about aerosol particles. This information is difficult to extract from standard SP-AMS mass spectra because they are complicated by extensive fragmentation from the harsh 70 eV EI ionization scheme that is typically used in these instruments. Thus, in this work synchotron-generated vacuum ultraviolet (VUV) light in the 8-14 eV range is used to measure VUV-SP-AMS spectra with minimal fragmentation. VUV-SP-AMS spectra of commercially available carbon black, fullerene black, and laboratory generated flame soots were obtained. Small carbon cluster cations (C(+)-C5(+)) were found to dominate the VUV-SP-AMS spectra of all the samples, indicating that the corresponding neutral clusters are key products of the SP vaporization process. Intercomparisons of carbon cluster ratios observed in VUV-SP-AMS and SP-AMS spectra are used to confirm spectral features that could be used to distinguish between different types of refractory carbon particles. VUV-SP-AMS spectra of oxidized organic species adsorbed on absorbing cores are also examined and found to display less thermally induced decomposition and fragmentation than spectra obtained with thermal vaporization at 200 °C (the minimum temperature needed to quantitatively vaporize ambient oxidized organic aerosol with a continuously heated surface). The particle cores

  13. Composition and hygroscopicity of aerosol particles at Mt. Lu in South China: Implications for acid precipitation

    NASA Astrophysics Data System (ADS)

    Li, Weijun; Chi, Jianwei; Shi, Zongbo; Wang, Xinfeng; Chen, Bin; Wang, Yan; Li, Tao; Chen, Jianmin; Zhang, Daizhou; Wang, Zifa; Shi, Chune; Liu, Liangke; Wang, Wenxing

    2014-09-01

    Physicochemical properties of aerosol particles were studied at Mt. Lu, an elevated site (115°59‧E, 29°35‧N, 1165 m) within the acid precipitation area. Northeast winds transport copious amounts of air pollutants and water vapor from the Yangtze River Delta into this acid precipitation area. NH4+ and SO42- are the dominant ions in PM2.5 and determine aerosol acidity. Individual particle analysis shows abundant S-rich and metals (i.e. Fe-, Zn-, Mn-, and Pb-rich) particles. Unlike aerosol particles in North China and urban areas, there are little soot and mineral particles at Mt. Lu. Lack of mineral particles contributed to the higher acidity in precipitation in the research area. Nano-sized spherical metal particles were observed to be embedded in 37% of S-rich particles. These metal particles were likely originated from heavy industries and fired-power plants. Hygroscopic experiments show that most particles start to deliquesce at 73-76% but organic coating lowers the particle deliquescence relative humidity (DRH) to 63-73%. The DRHs of these aerosol particles are clearly smaller than that of pure ammonium sulfate particles which is 80%. Since RH in ambient air was relatively high, ranging from 65% to 85% during our study period, most particles at our sampling site were in liquid phase. Our results suggest that liquid phase reactions in aerosol particles may contribute to SO2 to sulfuric acid conversion in the acid precipitation area.

  14. Chemical composition and sources of coastal marine aerosol particles during the 2008 VOCALS-REx campaign

    SciTech Connect

    Lee, Y. -N.; Springston, S.; Jayne, J.; Wang, J.; Hubbe, J.; Senum, G.; Kleinman, L.; Daum, P. H.

    2014-01-01

    The chemical composition of aerosol particles (Dp ≤ 1.5 μm) was measured over the southeast Pacific Ocean during the VAMOS (Variability of the American Monsoon Systems) Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-Rex) between 16 October and 15 November 2008 using the US Department of Energy (DOE) G-1 aircraft. The objective of these flights was to gain an understanding of the sources and evolution of these aerosols, and of how they interact with the marine stratus cloud layer that prevails in this region of the globe. Our measurements showed that the marine boundary layer (MBL) aerosol mass was dominated by non-sea-salt SO42−, followed by Na+, Cl, Org (total organics), NH4+, and NO3, in decreasing order of importance; CH3SO3 (MSA), Ca2+, and K+ rarely exceeded their limits of detection. Aerosols were strongly acidic with a NH4+ to SO42− equivalents ratio typically < 0.3. Sea-salt aerosol (SSA) particles, represented by NaCl, exhibited Cl deficits caused by both HNO3 and H2SO4, but for the most part were externally mixed with particles, mainly SO42−. SSA contributed only a small fraction of the total accumulation mode particle number concentration. It was inferred that all aerosol species (except SSA) were of predominantly continental origin because of their strong land-to-sea concentration gradient. Comparison of relative changes in median values suggests that (1) an oceanic source of NH3 is present between 72° W and 76° W, (2) additional organic aerosols from biomass burns or biogenic precursors were emitted from coastal regions south of 31° S, with possible cloud processing, and (3) free tropospheric (FT) contributions to MBL gas and aerosol

  15. Sources and composition of submicron organic mass in marine aerosol particles

    DOE PAGES

    Frossard, Amanda A.; Russell, Lynn M.; Burrows, Susannah M.; ...

    2014-11-27

    Recent studies have proposed a variety of interpretations of the sources and composition of atmospheric marine aerosol particles (aMA) based on a range of physical and chemical measurements collected during open-ocean research cruises. To investigate the processes that affect marine organic particles, this study uses the characteristic functional group composition (from Fourier transform infrared (FTIR) spectroscopy) of aMAP from five ocean regions to show that: (i) The organic functional group composition of aMAP that can be identified as atmospheric primary marine (ocean-derived) aerosol (aPMA) is 65±12% hydroxyl, 21±9% alkane, 6±6% amine, and 7±8% carboxylic acid functional groups. Contributions from photochemicalmore » reactions add carboxylic acid groups (15%-25%), shipping effluent in seawater and ship emissions add additional alkane groups (up to 70%), and coastal emissions mix in alkane and carboxylic acid groups from coastal pollution sources. (ii) The organic composition of aPMA is nearly identical to model generated primary marine aerosol particles (gPMA) from bubbled seawater (55% hydroxyl, 32% alkane, and 13% amine functional groups), indicating that its overall functional group composition is the direct consequence of the organic constituents of the seawater source. (iii) While the seawater organic functional group composition was nearly invariant across all three ocean regions studied, the gPMA alkane group fraction increased with chlorophyll-a concentrations (r = 0.79). gPMA from productive seawater had a larger fraction of alkane functional groups (35%) compared to gPMA from non-productive seawater (16%), likely due to the presence of surfactants in productive seawater that stabilize the bubble film and lead to preferential drainage of the more soluble (lower alkane group fraction) organic components. gPMA has a hydroxyl group absorption peak location characteristic of monosaccharides and disaccharides, where the seawater OM hydroxyl group

  16. Sources and composition of submicron organic mass in marine aerosol particles

    SciTech Connect

    Frossard, Amanda A.; Russell, Lynn M.; Burrows, Susannah M.; Elliott, Scott M.; Bates, Timothy S.; Quinn, Patricia K.

    2014-11-27

    Recent studies have proposed a variety of interpretations of the sources and composition of atmospheric marine aerosol particles (aMA) based on a range of physical and chemical measurements collected during open-ocean research cruises. To investigate the processes that affect marine organic particles, this study uses the characteristic functional group composition (from Fourier transform infrared (FTIR) spectroscopy) of aMAP from five ocean regions to show that: (i) The organic functional group composition of aMAP that can be identified as atmospheric primary marine (ocean-derived) aerosol (aPMA) is 65±12% hydroxyl, 21±9% alkane, 6±6% amine, and 7±8% carboxylic acid functional groups. Contributions from photochemical reactions add carboxylic acid groups (15%-25%), shipping effluent in seawater and ship emissions add additional alkane groups (up to 70%), and coastal emissions mix in alkane and carboxylic acid groups from coastal pollution sources. (ii) The organic composition of aPMA is nearly identical to model generated primary marine aerosol particles (gPMA) from bubbled seawater (55% hydroxyl, 32% alkane, and 13% amine functional groups), indicating that its overall functional group composition is the direct consequence of the organic constituents of the seawater source. (iii) While the seawater organic functional group composition was nearly invariant across all three ocean regions studied, the gPMA alkane group fraction increased with chlorophyll-a concentrations (r = 0.79). gPMA from productive seawater had a larger fraction of alkane functional groups (35%) compared to gPMA from non-productive seawater (16%), likely due to the presence of surfactants in productive seawater that stabilize the bubble film and lead to preferential drainage of the more soluble (lower alkane group fraction) organic components. gPMA has a hydroxyl group absorption peak location characteristic of monosaccharides and disaccharides, where the seawater OM hydroxyl group peak

  17. Comparison of cloud residual and background aerosol particle composition during the hill cap cloud experiment HCCT 2010 in Central Germany

    NASA Astrophysics Data System (ADS)

    Roth, A.; Mertes, S.; van Pinxteren, D.; Klimach, T.; Herrmann, H.; Schneider, J.; Borrmann, S.

    2013-12-01

    Physical and chemical characterization of cloud residual and background aerosol particles as well as aerosol-cloud interactions were investigated during the Hill Cap Cloud Thuringia (HCCT) experiment in September and October 2010 on the mountain site Schmücke (938m a.s.l.) in Germany. Background aerosol particles were sampled by an interstitial inlet whereas cloud droplets from orographic clouds were collected by a counter flow virtual impactor (CVI). Chemical composition analysis and sizing of the particles was done by single particle mass spectrometry using the bipolar Aircraft-based Laser Ablation Aerosol Mass Spectrometer (ALABAMA, particle diameter range 150 nm - 900 nm; Brands et al., 2011) and by two Aerodyne Aerosol Mass Spectrometers (C-ToF, HR-ToF). Supplementary, the particle size distribution was measured with an optical particle counter (OPC, size range 0.25 μm - 32 μm). During the field campaign about 21000 positive and negative single particle mass spectra could be obtained from cloud residual particles and about 239000 from background aerosol particles. The data were clustered by means of the fuzzy c-means algorithm. The resulting clusters consisting of mass spectra with similar fragmentation patterns were, dependent on presence and combination of peaks, assigned to certain particle types. For both sampled particle types a large portion is internally mixed with nitrate and/or sulfate. This might be an explanation, why a comparison of the composition shows a higher fraction of soot particles and amine-containing particles among cloud residuals. Furthermore cloud residuals show a decreased fraction of particles being internally mixed only with nitrate (10%) compared to background aerosol particles (19%) of the same air masses, whereas the fraction of particles containing both nitrate and sulfate increases from 39% to 63% indicating cloud processing by uptake and oxidation of SO2 (Harris et al, 2013). Brands, M., Kamphus, M., Böttger, T., Schneider

  18. Chemical composition and sources of aerosol particles at Zeppelin Mountain (Ny Ålesund, Svalbard): An electron microscopy study

    NASA Astrophysics Data System (ADS)

    Weinbruch, Stephan; Wiesemann, David; Ebert, Martin; Schütze, Katharina; Kallenborn, Roland; Ström, Johan

    2012-03-01

    Aerosol particles were collected at the Zeppelin Mountain Atmospheric Research Station (474 m asl) near Ny Ålesund (Svalbard, Norway) on 27 different days between July 2007 and December 2008. The size, morphology and chemical composition of 57,617 individual particles were studied by high-resolution scanning electron microscopy and energy-dispersive X-ray microanalysis. Based on chemical composition, morphology, mixing state and stability under electron bombardment, the particles were assigned to one of the following groups: sea salt, aged sea salt, Ca sulphates, Na sulphates, carbonates, soot, silicates, fly ashes, secondary aerosol, secondary aerosol plus sodium, secondary aerosol plus soot, mixed particles and others. Sea salt, aged sea salt, silicates and mixed particles (mixtures of sea salt, silicates and Ca sulphates) are the most abundant groups for particles with aerodynamic diameters > 0.5 μm, secondary aerosol, mixed particles and secondary aerosol with soot inclusions below 0.5 μm. Silicate fly ashes (major source coal burning) and metal fly ashes (from metallurgical high temperature processes) occur only at very low number concentrations. In contrast to previous work, the fly ash abundance is not correlated with air masses that crossed industrialized regions in Central and Eastern Europe, Scandinavia or Russia. These observations indicate a significant reduction of long-range transport of heavy metals to Svalbard. Soot (external and internally mixed with secondary aerosol) shows a pronounced seasonal pattern with a much lower abundance during summer compared to spring, autumn and winter. The soot abundance is not correlated with the air mass back-trajectories. During summer (July and August), soot was only observed when cruise ships were present in the area around Ny Ålesund (Kongsfjorden). Pronounced seasonal patterns were observed for the abundance of the mineral dust component which is generally lower in summer compared to the other seasons. The

  19. MATRIX-ASSISTED LASER DESORPTION IONIZATION OF SIZE AND COMPOSITION SELECTED AEROSOL PARTICLES. (R823980)

    EPA Science Inventory

    Matrix-assisted laser desorption/ionization (MALDI) was performed on individual,
    size-selected aerosol particles in the 2-8 mu m diameter range, Monodisperse aerosol droplets
    containing matrix, analyte, and solvent were generated and entrained in a dry stream of air, The dr...

  20. 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

  1. Identifying organic aerosol sources by comparing functional group composition in chamber and atmospheric particles.

    PubMed

    Russell, Lynn M; Bahadur, Ranjit; Ziemann, Paul J

    2011-03-01

    Measurements of submicron particles by Fourier transform infrared spectroscopy in 14 campaigns in North America, Asia, South America, and Europe were used to identify characteristic organic functional group compositions of fuel combustion, terrestrial vegetation, and ocean bubble bursting sources, each of which often accounts for more than a third of organic mass (OM), and some of which is secondary organic aerosol (SOA) from gas-phase precursors. The majority of the OM consists of alkane, carboxylic acid, hydroxyl, and carbonyl groups. The organic functional groups formed from combustion and vegetation emissions are similar to the secondary products identified in chamber studies. The near absence of carbonyl groups in the observed SOA associated with combustion is consistent with alkane rather than aromatic precursors, and the absence of organonitrate groups can be explained by their hydrolysis in humid ambient conditions. The remote forest observations have ratios of carboxylic acid, organic hydroxyl, and nonacid carbonyl groups similar to those observed for isoprene and monoterpene chamber studies, but in biogenic aerosols transported downwind of urban areas the formation of esters replaces the acid and hydroxyl groups and leaves only nonacid carbonyl groups. The carbonyl groups in SOA associated with vegetation emissions provides striking evidence for the mechanism of esterification as the pathway for possible oligomerization reactions in the atmosphere. Forest fires include biogenic emissions that produce SOA with organic components similar to isoprene and monoterpene chamber studies, also resulting in nonacid carbonyl groups in SOA.

  2. Hygroscopicity and chemical composition of Antarctic sub-micrometre aerosol particles and observations of new particle formation

    NASA Astrophysics Data System (ADS)

    Asmi, E.; Frey, A.; Virkkula, A.; Ehn, M.; Manninen, H. E.; Timonen, H.; Tolonen-Kivimäki, O.; Aurela, M.; Hillamo, R.; Kulmala, M.

    2009-12-01

    The Antarctic near-coastal sub-micrometre aerosol particle features in summer were characterised based on measured data on aerosol hygroscopicity, size distributions, volatility and chemical ion and organic carbon mass concentrations. Hysplit model was used to calculate the history of the air masses to predict the particle origin. Additional measurements of meteorological parameters were utilised. The hygroscopic properties of particles mostly resembled those of marine aerosols. The measurements took place at 130 km from the Southern Ocean, which was the most significant factor affecting the particle properties. This is explained by the lack of additional sources on the continent of Antarctica. The Southern Ocean was thus a likely source of the particles and nucleating and condensing vapours. The particles were very hygroscopic (HGF 1.75 at 90 nm) and very volatile. Most of the sub-100 nm particle volume volatilised below 100 °C. Based on chemical data, particle hygroscopic and volatile properties were explained by a large fraction of non-neutralised sulphuric acid together with organic material. The hygroscopic growth factors assessed from chemical data were similar to measured. Hygroscopicity was higher in dry continental air masses compared with the moist marine air masses. This was explained by the aging of the marine organic species and lower methanesulphonic acid volume fraction together with the changes in the inorganic aerosol chemistry as the aerosol had travelled long time over the continental Antarctica. Special focus was directed in detailed examination of the observed new particle formation events. Indications of the preference of negative over positive ions in nucleation could be detected. However, in a detailed case study, the neutral particles dominated the particle formation process. Freshly nucleated particles had the smallest hygroscopic growth factors, which increased subsequent to particle aging.

  3. Hygroscopicity and chemical composition of Antarctic sub-micrometre aerosol particles and observations of new particle formation

    NASA Astrophysics Data System (ADS)

    Asmi, E.; Frey, A.; Virkkula, A.; Ehn, M.; Manninen, H. E.; Timonen, H.; Tolonen-Kivimäki, O.; Aurela, M.; Hillamo, R.; Kulmala, M.

    2010-05-01

    The Antarctic near-coastal sub-micrometre aerosol particle features in summer were characterised based on measured data on aerosol hygroscopicity, size distributions, volatility and chemical ion and organic carbon mass concentrations. Hysplit model was used to calculate the history of the air masses to predict the particle origin. Additional measurements of meteorological parameters were utilised. The hygroscopic properties of particles mostly resembled those of marine aerosols. The measurements took place at 130 km from the Southern Ocean, which was the most significant factor affecting the particle properties. This is explained by the lack of additional sources on the continent of Antarctica. The Southern Ocean was thus a likely source of the particles and nucleating and condensing vapours. The particles were very hygroscopic (HGF 1.75 at 90 nm) and very volatile. Most of the sub-100 nm particle volume volatilised below 100 °C. Based on chemical data, particle hygroscopic and volatile properties were explained by a large fraction of non-neutralised sulphuric acid together with organic material. The hygroscopic growth factors assessed from chemical data were similar to measured. Hygroscopicity was higher in dry continental air masses compared with the moist marine air masses. This was explained by the aging of the marine organic species and lower methanesulphonic acid volume fraction together with the changes in the inorganic aerosol chemistry as the aerosol had travelled long time over the continental Antarctica. Special focus was directed in detailed examination of the observed new particle formation events. Indications of the preference of negative over positive ions in nucleation could be detected. However, in a detailed case study, the neutral particles dominated the particle formation process. Freshly nucleated particles had the smallest hygroscopic growth factors, which increased subsequent to particle aging.

  4. On the composition of ammonia-sulfuric-acid ion clusters during aerosol particle formation

    NASA Astrophysics Data System (ADS)

    Schobesberger, S.; Franchin, A.; Bianchi, F.; Rondo, L.; Duplissy, J.; Kürten, A.; Ortega, I. K.; Metzger, A.; Schnitzhofer, R.; Almeida, J.; Amorim, A.; Dommen, J.; Dunne, E. M.; Ehn, M.; Gagné, S.; Ickes, L.; Junninen, H.; Hansel, A.; Kerminen, V.-M.; Kirkby, J.; Kupc, A.; Laaksonen, A.; Lehtipalo, K.; Mathot, S.; Onnela, A.; Petäjä, T.; Riccobono, F.; Santos, F. D.; Sipilä, M.; Tomé, A.; Tsagkogeorgas, G.; Viisanen, Y.; Wagner, P. E.; Wimmer, D.; Curtius, J.; Donahue, N. M.; Baltensperger, U.; Kulmala, M.; Worsnop, D. R.

    2015-01-01

    The formation of particles from precursor vapors is an important source of atmospheric aerosol. Research at the Cosmics Leaving OUtdoor Droplets (CLOUD) facility at CERN tries to elucidate which vapors are responsible for this new-particle formation, and how in detail it proceeds. Initial measurement campaigns at the CLOUD stainless-steel aerosol chamber focused on investigating particle formation from ammonia (NH3) and sulfuric acid (H2SO4). Experiments were conducted in the presence of water, ozone and sulfur dioxide. Contaminant trace gases were suppressed at the technological limit. For this study, we mapped out the compositions of small NH3-H2SO4 clusters over a wide range of atmospherically relevant environmental conditions. We covered [NH3] in the range from < 2 to 1400 pptv, [H2SO4] from 3.3 × 106 to 1.4 × 109 cm-3 (0.1 to 56 pptv), and a temperature range from -25 to +20 °C. Negatively and positively charged clusters were directly measured by an atmospheric pressure interface time-of-flight (APi-TOF) mass spectrometer, as they initially formed from gas-phase NH3 and H2SO4, and then grew to larger clusters containing more than 50 molecules of NH3 and H2SO4, corresponding to mobility-equivalent diameters greater than 2 nm. Water molecules evaporate from these clusters during sampling and are not observed. We found that the composition of the NH3-H2SO4 clusters is primarily determined by the ratio of gas-phase concentrations [NH3] / [H2SO4], as well as by temperature. Pure binary H2O-H2SO4 clusters (observed as clusters of only H2SO4) only form at [NH3] / [H2SO4] < 0.1 to 1. For larger values of [NH3] / [H2SO4], the composition of NH3-H2SO4 clusters was characterized by the number of NH3 molecules m added for each added H2SO4 molecule n (Δm/Δ n), where n is in the range 4-18 (negatively charged clusters) or 1-17 (positively charged clusters). For negatively charged clusters, Δ m/Δn saturated between 1 and 1.4 for [NH3] / [H2SO4] > 10. Positively

  5. On the composition of ammonia-sulfuric acid clusters during aerosol particle formation

    NASA Astrophysics Data System (ADS)

    Schobesberger, S.; Franchin, A.; Bianchi, F.; Rondo, L.; Duplissy, J.; Kürten, A.; Ortega, I. K.; Metzger, A.; Schnitzhofer, R.; Almeida, J.; Amorim, A.; Dommen, J.; Dunne, E. M.; Ehn, M.; Gagné, S.; Ickes, L.; Junninen, H.; Hansel, A.; Kerminen, V.-M.; Kirkby, J.; Kupc, A.; Laaksonen, A.; Lehtipalo, K.; Mathot, S.; Onnela, A.; Petäjä, T.; Riccobono, F.; Santos, F. D.; Sipilä, M.; Tomé, A.; Tsagkogeorgas, G.; Viisanen, Y.; Wagner, P. E.; Wimmer, D.; Curtius, J.; Donahue, N. M.; Baltensperger, U.; Kulmala, M.; Worsnop, D. R.

    2014-05-01

    The formation of particles from precursor vapors is an important source of atmospheric aerosol. Research at the Cosmics Leaving OUtdoor Droplets (CLOUD) facility at CERN tries to elucidate which vapors are responsible for this new particle formation, and how in detail it proceeds. Initial measurement campaigns at the CLOUD stainless-steel aerosol chamber focused on investigating particle formation from ammonia (NH3) and sulfuric acid (H2SO4). Experiments were conducted in the presence of water, ozone and sulfur dioxide. Contaminant trace gases were suppressed at the technological limit. For this study, we mapped out the compositions of small NH3-H2SO4 clusters over a wide range of atmospherically relevant environmental conditions. We covered [NH3] in the range from <2 to 1400 pptv, [H2SO4] from 3.3 × 106 to 1.4 × 109 cm-3, and a temperature range from -25 to +20 °C. Negatively and positively charged clusters were directly measured by an atmospheric pressure interface time-of-flight (APi-TOF) mass spectrometer, as they initially formed from gas-phase NH3 and H2SO4, and then grew to larger clusters containing more than 50 molecules of NH3 and H2SO4, corresponding to mobility-equivalent diameters greater than 2 nm. Water molecules evaporate from these clusters during sampling and are not observed. We found that the composition of the NH3-H2SO4 clusters is primarily determined by the ratio of gas-phase concentrations [NH3] / [H2SO4], as well as by temperature. Pure binary H2O-H2SO4 clusters (observed as clusters of only H2SO4) only form at [NH3] / [H2SO4]<0.1 to 1. For larger values of [NH3] / [H2SO4], the composition of NH3-H2SO4 clusters was characterized by the number of NH3 molecules m added for each added H2SO4 molecule n (Δm / Δn), where n is in the range 4-18 (negatively charged clusters) or 1-17 (positively charged clusters). For negatively charged clusters, Δm / Δn saturated between 1 and 1.4 for [NH3] / [H2SO4]>10. Positively charged clusters grew on

  6. Organic aerosol molecular composition and gas-particle partitioning coefficients at a Mediterranean site (Corsica).

    PubMed

    Rossignol, Stéphanie; Couvidat, Florian; Rio, Caroline; Fable, Sébastien; Grignion, Guillaume; Savelli; Pailly, Olivier; Leoz-Garziandia, Eva; Doussin, Jean-Francois; Chiappini, Laura

    2016-02-01

    Molecular speciation of atmospheric organic matter was investigated during a short summer field campaign performed in a citrus fruit field in northern Corsica (June 2011). Aimed at assessing the performance on the field of newly developed analytical protocols, this work focuses on the molecular composition of both gas and particulate phases and provides an insight into partitioning behavior of the semi-volatile oxygenated fraction. Limonene ozonolysis tracers were specifically searched for, according to gas chromatography-mass spectrometry (GC-MS) data previously recorded for smog chamber experiments. A screening of other oxygenated species present in the field atmosphere was also performed. About sixty polar molecules were positively or tentatively identified in gas and/or particle phases. These molecules comprise a wide range of branched and linear, mono and di-carbonyls (C3-C7), mono and di-carboxylic acids (C3-C18), and compounds bearing up to three functionalities. Among these compounds, some can be specifically attributed to limonene oxidation and others can be related to α- or β-pinene oxidation. This provides an original snapshot of the organic matter composition at a Mediterranean site in summer. Furthermore, for compounds identified and quantified in both gaseous and particulate phases, an experimental gas/particle partitioning coefficient was determined. Several volatile products, which are not expected in the particulate phase assuming thermodynamic equilibrium, were nonetheless present in significant concentrations. Hypotheses are proposed to explain these observations, such as the possible aerosol viscosity that could hinder the theoretical equilibrium to be rapidly reached.

  7. Combined use of optical and electron microscopic techniques for the measurement of hygroscopic property, chemical composition, and morphology of individual aerosol particles.

    PubMed

    Ahn, Kang-Ho; Kim, Sun-Man; Jung, Hae-Jin; Lee, Mi-Jung; Eom, Hyo-Jin; Maskey, Shila; Ro, Chul-Un

    2010-10-01

    In this work, an analytical method for the characterization of the hygroscopic property, chemical composition, and morphology of individual aerosol particles is introduced. The method, which is based on the combined use of optical and electron microscopic techniques, is simple and easy to apply. An optical microscopic technique was used to perform the visual observation of the phase transformation and hygroscopic growth of aerosol particles on a single particle level. A quantitative energy-dispersive electron probe X-ray microanalysis, named low-Z particle EPMA, was used to perform a quantitative chemical speciation of the same individual particles after the measurement of the hygroscopic property. To validate the analytical methodology, the hygroscopic properties of artificially generated NaCl, KCl, (NH(4))(2)SO(4), and Na(2)SO(4) aerosol particles of micrometer size were investigated. The practical applicability of the analytical method for studying the hygroscopic property, chemical composition, and morphology of ambient aerosol particles is demonstrated.

  8. Activation of "synthetic ambient" aerosols - Relation to chemical composition of particles <100 nm

    NASA Astrophysics Data System (ADS)

    Burkart, J.; Hitzenberger, R.; Reischl, G.; Bauer, H.; Leder, K.; Puxbaum, H.

    2012-07-01

    Cloud condensation nuclei (CCN) are an important fraction of atmospheric aerosols because of their role in cloud formation. Experimental studies focus either on direct field measurements of complex ambient aerosols or laboratory investigations on well defined aerosols produced from single substances or substance mixtures. In this study, we focussed on the ultrafine aerosol because in terms of number concentration, the majority of the CCN are expected to have sizes in this range. A field study was performed from July 2007 to October 2008 to investigate the activation behaviour of the atmospheric aerosol in Vienna (Burkart et al., 2011). Filter samples of the aerosol <0.1 μm aerodynamic equivalent diameter were collected, elutriated and used to generate "synthetic ambient" aerosol in a nebulizer. Chemical analyses of the ultrafine water soluble material were also performed. The CCN properties of the "synthetic ambient" aerosol were obtained using the University of Vienna CCN counter (Giebl et al., 2002; Dusek et al., 2006b) at a nominal supersaturation (SS) of 0.5%. Activation diameters dact ranged from 54.5 nm to 66 nm, were larger than dact of typical single inorganic salts and showed no seasonal pattern in contrast to the fraction of water soluble organic carbon (WSOC), which ranged from 44% in spring to 15% in winter. The average hygroscopicity parameter κ (Petters and Kreidenweis, 2007) obtained from the activation curves ranged from 0.20 to 0.30 (average 0.24), which was significantly lower than κchem calculated from the chemical composition (0.43 ± 0.07).

  9. Size-segregated compositional analysis of aerosol particles collected in the European Arctic during the ACCACIA campaign

    NASA Astrophysics Data System (ADS)

    Young, G.; Jones, H. M.; Darbyshire, E.; Baustian, K. J.; McQuaid, J. B.; Bower, K. N.; Connolly, P. J.; Gallagher, M. W.; Choularton, T. W.

    2016-03-01

    Single-particle compositional analysis of filter samples collected on board the Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 aircraft is presented for six flights during the springtime Aerosol-Cloud Coupling and Climate Interactions in the Arctic (ACCACIA) campaign (March-April 2013). Scanning electron microscopy was utilised to derive size-segregated particle compositions and size distributions, and these were compared to corresponding data from wing-mounted optical particle counters. Reasonable agreement between the calculated number size distributions was found. Significant variability in composition was observed, with differing external and internal mixing identified, between air mass trajectory cases based on HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) analyses. Dominant particle classes were silicate-based dusts and sea salts, with particles notably rich in K and Ca detected in one case. Source regions varied from the Arctic Ocean and Greenland through to northern Russia and the European continent. Good agreement between the back trajectories was mirrored by comparable compositional trends between samples. Silicate dusts were identified in all cases, and the elemental composition of the dust was consistent for all samples except one. It is hypothesised that long-range, high-altitude transport was primarily responsible for this dust, with likely sources including the Asian arid regions.

  10. Changes in background aerosol composition in Finland during polluted and clean periods studied by TEM/EDX individual particle analysis

    NASA Astrophysics Data System (ADS)

    Niemi, J. V.; Saarikoski, S.; Tervahattu, H.; Mäkelä, T.; Hillamo, R.; Vehkamäki, H.; Sogacheva, L.; Kulmala, M.

    2006-07-01

    Aerosol samples were collected at a rural background site in southern Finland in May 2004. The elemental composition, morphology and mixing state of individual aerosol particles in three size fractions were studied using transmission electron microscopy (TEM) coupled with energy dispersive X-ray (EDX) microanalyses. The TEM/EDX results were complemented with the size-segregated bulk chemical measurements of selected ions and organic and elemental carbon. Many of the particles in PM0.2-1 and PM1-3.3 size fractions were strongly internally mixed with S, C and/or N. The major particle types in all PM0.2-1 samples were ammonium sulphates with/without carbon and dark inclusion(s) (number proportion of particles 54-86%), carbon/sulphate mixture with dark inclusions(s) (4-10%), internally mixed soot/sulphate particles (2-22%), soot (0-12%) and K-rich particles with S and/or C (0-9%). During the pollution episode (PM1.6~18 μg m-3, the proportion of Ca-rich particles was very high (26-48%) in the PM1-3.3 and PM3.3-11 samples, while the PM0.2-1 and PM1-3.3 samples contained elevated proportions of silicates (22-33%, also fly ash particles), metal oxides/hydroxides (1-9%) and tar balls (1-4%). These aerosols originated mainly from polluted areas of Eastern Europe, and some open biomass burning smoke was also brought by long-range transport. During the clean period (PM1.6~2 μg m-3, when air masses arrived from the Arctic Ocean, PM1-3.3 samples contained mainly sea salt particles (67-89%) with a variable rate of Cl substitution (mainly by NO3-. During the intermediate period (PM1.6~5 μg m-3, the PM1-3.3 sample contained porous (sponge-like) Na-rich particles (35%) with abundant S, K and O. They might originate from the burning of wood pulp wastes of paper industry. The proportion of biological particles and C-rich fragments (probably also biological origin) were highest in the PM3.3-11 samples (0-81% and 0-22%, respectively). The origin of different particle types and the

  11. Aerosol fine fraction in the Venice Lagoon: Particle composition and sources

    NASA Astrophysics Data System (ADS)

    Prodi, F.; Belosi, F.; Contini, D.; Santachiara, G.; Di Matteo, L.; Gambaro, A.; Donateo, A.; Cesari, D.

    2009-04-01

    The work presents a characterisation of aerosol sampled during three campaigns conducted in the Venice Lagoon from 30 June to 21 July 2004, from 15 February to 10 March 2005 and from 8 May to 25 May 2006. The results yield information about the physical-chemical characteristics of fine aerosol, the possible sources and its fate. Sulphate (SO 42-), nitrate (NO 3-) and ammonium (NH 4+) are identified as the main water soluble components. The sum of these ions in the spring campaign 2006 varies from 51% to nearly 100% of PM2.5 fraction aerosol. NH 4+ is found to be significantly correlated to non-sea-salt sulphate (nss-SO 42-) and NO 3-, thus indicating the prevalent presence of ammonium nitrate and sulphate. The overall lack of a clear diurnal and seasonal cycle of sulphate suggests a transport from the Po Valley, while the diurnal and seasonal profile of nitrate concentrations suggests a prevalence of local generation. Sulphates from sea water through oxidation of dimethylsulfide (DMS) are not negligible (about 10% of the anthropogenic sulphate). The marine aerosol contribution to PM1 and PM2.5 fractions, calculated using Na + as a tracer of sea-salts, is low (range 1-6%). In some cases chlorine depletion is observed. The content of chlorine in the aerosol particle is mostly higher than expected for marine environments (considered on the basis of Cl -/Na + ratio). Therefore, specific sources for the element have been suggested. Oxalic acid anion, which accounts for 55% of the organic compounds examined, presents mean values 180 ng m - 3 and 161 ng m - 3 in the winter and spring campaigns, comparable with reported values in low polluted urban areas. In the winter campaign there is a high correlation between formate and acetate ( R2 = 0.93), suggesting that a common source makes a high contribution to the measured concentrations.

  12. Exploring the variability of aerosol particle composition in the Arctic: a study from the springtime ACCACIA campaign

    NASA Astrophysics Data System (ADS)

    Young, G.; Jones, H. M.; Darbyshire, E.; Baustian, K. J.; McQuaid, J. B.; Bower, K. N.; Connolly, P. J.; Gallagher, M. W.; Choularton, T. W.

    2015-10-01

    Single-particle compositional analysis of filter samples collected on-board the FAAM BAe-146 aircraft is presented for six flights during the springtime Aerosol-Cloud Coupling and Climate Interactions in the Arctic (ACCACIA) campaign (March-April 2013). Scanning electron microscopy was utilised to derive size distributions and size-segregated particle compositions. These data were compared to corresponding data from wing-mounted optical particle counters and reasonable agreement between the calculated number size distributions was found. Significant variability in composition was observed, with differing external and internal mixing identified, between air mass trajectory cases based on HYSPLIT analyses. Dominant particle classes were silicate-based dusts and sea salts, with particles notably rich in K and Ca detected in one case. Source regions varied from the Arctic Ocean and Greenland through to northern Russia and the European continent. Good agreement between the back trajectories was mirrored by comparable compositional trends between samples. Silicate dusts were identified in all cases, and the elemental composition of the dust was consistent for all samples except one. It is hypothesised that long-range, high-altitude transport was primarily responsible for this dust, with likely sources including the Asian arid regions.

  13. Changes in background aerosol composition in Finland during polluted and clean periods studied by TEM/EDX individual particle analysis

    NASA Astrophysics Data System (ADS)

    Niemi, J. V.; Saarikoski, S.; Tervahattu, H.; Mäkelä, T.; Hillamo, R.; Vehkamäki, H.; Sogacheva, L.; Kulmala, M.

    2006-11-01

    Aerosol samples were collected at a rural background site in southern Finland in May 2004 during pollution episode (PM1~16 µg m-3, backward air mass trajectories from south-east), intermediate period (PM1~5 µg m-3, backtrajectories from north-east) and clean period (PM1~2 µg m-3, backtrajectories from north-west/north). The elemental composition, morphology and mixing state of individual aerosol particles in three size fractions were studied using transmission electron microscopy (TEM) coupled with energy dispersive X-ray (EDX) microanalyses. The TEM/EDX results were complemented with the size-segregated bulk chemical measurements of selected ions and organic and elemental carbon. Many of the particles in PM0.2-1 and PM1-3.3 size fractions were strongly internally mixed with S, C and/or N. The major particle types in PM0.2-1 samples were 1) soot and 2) (ammonium)sulphates and their mixtures with variable amounts of C, K, soot and/or other inclusions. Number proportions of those two particle groups in PM0.2-1 samples were 0-12% and 83-97%, respectively. During the pollution episode, the proportion of Ca-rich particles was very high (26-48%) in the PM1-3.3 and PM3.3-11 samples, while the PM0.2-1 and PM1-3.3 samples contained elevated proportions of silicates (22-33%), metal oxides/hydroxides (1-9%) and tar balls (1-4%). These aerosols originated mainly from polluted areas of Eastern Europe, and some open biomass burning smoke was also brought by long-range transport. During the clean period, when air masses arrived from the Arctic Ocean, PM1-3.3 samples contained mainly sea salt particles (67-89%) with a variable rate of Cl substitution (mainly by NO3-). During the intermediate period, the PM1-3.3 sample contained porous (sponge-like) Na-rich particles (35%) with abundant S, K and O. They might originate from the burning of wood pulp wastes of paper industry. The proportion of biological particles and C-rich fragments (probably also biological origin) were highest

  14. Time-resolved mass concentration, composition and sources of aerosol particles in a metropolitan underground railway station

    NASA Astrophysics Data System (ADS)

    Salma, Imre; Weidinger, Tamás; Maenhaut, Willy

    Aerosol samples were collected using a stacked filter unit (SFU) for PM10-2.0 and PM2.0 size fractions on the platform of a metropolitan underground railway station in downtown Budapest. Temporal variations in the PM10 mass concentration and wind speed and direction were determined with time resolutions of 30 and 4 s using a tapered-element oscillating microbalance (TEOM) and a wind monitor, respectively. Sample analysis involved gravimetry for particulate mass, and particle-induced X-ray emission spectrometry (PIXE) for elemental composition. Diurnal variation of the PM10 mass concentration exhibited two peaks, one at approximately 07:00 h and the other at approximately 17:00 h. The mean±SD PM10 mass concentration for working hours was 155±55 μg m -3. Iron, Mn, Ni, Cu, and Cr concentrations were higher than in outdoor air by factors between 5 and 20, showing substantial enrichment compared to both the average crustal rock composition and the average outdoor aerosol composition. Iron accounted for 40% and 46% of the PM10-2.0 and PM2.0 masses, respectively, and 72% of the PM10 mass was associated with the PM10-2.0 size fraction. The aerosol composition in the metro station (in particular the abundance of the metals mentioned above) is quite different from the average outdoor downtown composition. Mechanical wear and friction of electric conducting rails and bow sliding collectors, ordinary rails and wheels, as well as resuspension, were identified as the primary sources. Possible health implications based on comparison to various limit values and to data available for other underground railways are discussed.

  15. Composition-dependent freezing nucleation rates for HNO3/H2O aerosols resembling gravity-wave-perturbed stratospheric particles

    NASA Astrophysics Data System (ADS)

    Prenni, Anthony J.; Onasch, Timothy B.; Tisdale, Robert T.; Siefert, Ronald L.; Tolbert, Margaret A.

    1998-11-01

    Laboratory measurements are presented for the freezing kinetics of H2O/HNO3 aerosols over the temperature range of 188-204 K. For 2:1 H2O:HNO3 aerosols crystallizing to NAD we observed a maximum nucleation rate of J = 9.3×109 cm-3 s-1 at 194 K. This temperature is between the glass point of 161 K [Ji et al., 1993] and the melting point of 235.5 K [Ji et al., 1996]. This can be compared to a previous measurement of J = 6.7×109 cm-3 s-1 at 193 K [Disselkamp et al., 1996] and lower temperature measurements of J ≈ 1010-1012 cm-3 s-1 at 178.8 - 175.8 K [Bertram and Sloan, 1998a]. Measured nucleation rates decrease as the aerosol becomes dilute, but NAD formation is still observable for 2.5:1 H2O:HNO3 at temperatures near 195 K. In contrast, freezing of 3:1 H2O:HNO3 aerosol was not observed for constant temperature experiments throughout this temperature range, yielding an upper limit of J<1.5×109 cm-3 s-1. This is the lowest experimental value determined for 3:1 H2O:HNO3 freezing rates at these temperatures. From the measured freezing rates and knowledge of the free energy of diffusion the average interfacial free energy for NAD in a 2:1 H2O:HNO3 solution was determined to be σ = 25.2 ergs cm-2. A limit for the interfacial free energy was placed on 3:1 H2O:HNO3 particles, for which freezing was not observed. These data imply that if aerosols reach compositions more concentrated than 3:1 H2O:HNO3 in the atmosphere, NAD may play a role in polar stratospheric cloud formation.

  16. Measurements of aerosol-cloud interactions, including on-line particle chemical composition, at the Jungfraujoch Global Atmospheric Watch Station

    NASA Astrophysics Data System (ADS)

    Coe, H.; Allan, J. D.; Alfarra, M. R.; Williams, P. I.; Bower, K. N.; Gallagher, M. W.; Choularton, T. W.; Weingartner, E.; Corrigan, C.; Baltensperger, U.

    2003-04-01

    The Global Atmospheric Watch research laboratory is located in the Sphinx building, 3580 m asl; 46.55oN, 7.98oE on the Jungfraujoch in the Swiss Alps. The site is exposed to a wide range of conditions and frequently samples long range transported lower free tropospheric air, and is exposed to cloudy conditions. The Paul Scherrer Institute have previously developed a dual inlet system that allows measurements of the total sub-micron aerosol population (dry residuals and interstitial particles) and interstitial particles alone to be made alternately every few minutes. During July 2002 an Aerodyne Aerosol Mass Spectrometer was coupled to the dual inlet and was used to sample the composition of both the total particle distribution and the interstitial fraction and hence derive the mass loadings of the dry droplet residuals. In out of cloud conditions the aerosol composition can be linked to air mass history and age of the air mass. Microphysical measurements include cloud droplet size distributions made using an FSSP and also a new phase Doppler anemometry system. A comparison between these probes will be made. Two different types of cloud droplet spectra were observed. In the first type a large number of cloud droplets were measured with a single, narrow drop size distribution and modal diameter of around 10 um. In the second type, a bimodal cloud droplet spectrum occurred with a smaller mode (by number) at around 20 um, in addition to the 10 um mode. The aerosol mass spectrometry shows that the composition of the residuals from the two spectrum types is very different, the former type being composed mainly of sulphate, the latter a combination of nitrate, sulphate and organic material. We have also shown that the organic material observed is highly oxidized. We argue that the bimodality arises as a result of mixing of cloud droplets below the site that have been activated separately: the larger a less numerous mode in the widespread strato-cumulus forming under low

  17. Liquid-liquid phase separation in aerosol particles: Dependence on O:C, organic functionalities, and compositional complexity

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

    Atmospheric aerosol particles may undergo liquid-liquid phase separation (LLPS) when exposed to varying relative humidity. In this study we investigated the occurrence of LLPS for mixtures consisting of up to ten organic compounds, ammonium sulfate, and water in relationship with the organic oxygen-to-carbon (O:C) ratio. LLPS always occurred for O:C < 0.56, never occurred for O:C > 0.80, and depended on the specific types and compositions of organic functional groups in the regime 0.56 < O:C < 0.80. In the intermediate regime, mixtures with a high share of aromatic compounds shifted the limit of occurrence of LLPS to lower O:C ratios. 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 range typically between 0.2 and 1.0, LLPS is expected to be a common feature of tropospheric aerosols.

  18. Sulfur Isotopic Compositions of Individual Aerosol Particles from Below and Within Stratocumulus Clouds over the Southeast Pacific Ocean During VOCALS

    NASA Astrophysics Data System (ADS)

    Bose, M.; Anderson, J. R.; Twohy, C. H.; Williams, P.

    2012-12-01

    The VAMOS Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-Rex) was a large multi-national field experiment that collected data and samples from a region of the southeast Pacific with the world's largest stratocumulus cloud systems. Samples examined here are residues of cloud droplets and ambient particles from below the clouds collected during flights of the NCAR C-130 off the coast of Chile. Selected samples were studied using scanning electron microscopy (SEM) and secondary ion mass spectrometry (SIMS) in order to contribute to the understanding of the source of non-sea-salt sulfate in this region. Particles in the size range from 0.2 to 1μm diameter on holey and lacey carbon were characterized by SEM combined with energy dispersive spectrometry (EDS), thus identifying sulfur-containing particles. Subsequently, sulfur ion imaging of identified sea salt, ammonium sulfate and sodium sulfate particles was done with the Cameca Ametek NanoSIMS 50L at Arizona State University. A <1pA Cs+ beam was rastered over 5×5μm2 or 10×10μm2 areas while secondary ions (12C-, 16O-, 32S-, 34S-, 35Cl-) and secondary electrons were collected simultaneously at high mass resolution (m/Δm>10000). Each measurement typically consists of 5 to 8 frames (~5.4 min/frame). NIST barium sulfate and ammonium sulfate particles were used as isotopic standards. Preliminary analyses on a small pool of VOCALS individual particles show a wide range in sulfur isotopic compositions (δ34S = -56 to +41‰). In addition, the in-cloud particles are enriched in 32S, while the ambient particles exhibit 34S excesses. Isotopic data on a large inventory of particles is being currently acquired, which will be presented at the meeting. Data will be used to investigate sulfur sources (marine vs. continental) and the processing of aerosols through sulfate formation.

  19. Composition of carbonaceous smoke particles from prescribed burning of a Canadian boreal forest: 1. Organic aerosol characterization by gas chromatography

    SciTech Connect

    Mazurek, M.A.; Laterza, C.; Newman, L.; Daum, P.; Cofer, W.R. III; Levine, J.S.; Winstead, E.L.

    1995-06-01

    In this study we examine the molecular organic constituents (C8 to C40 lipid compounds) collected as smoke particles from a Canadian boreal forest prescribed burn. Of special interest are (1) the molecular identity of polar organic aerosols, and (2) the amount of polar organic matter relative to the total mass of aerosol particulate carbon. Organic extracts of smoke aerosol particles show complex distributions of the lipid compounds when analyzed by capillary gas chromatography/mass spectrometry. The molecular constituents present as smoke aerosol are grouped into non-polar (hydrocarbons) and polar {minus}2 oxygen atoms) subtractions. The dominant chemical species found in the boreal forest smoke aerosol are unaltered resin compounds (C20 terpenes) which are abundant in unburned conifer wood, plus thermally altered wood lignins and other polar aromatic hydrocarbons. Our results show that smoke aerosols contain molecular tracers which are related to the biofuel consumed. These smoke tracers can be related structurally back to the consumed softwood and hardwood vegetation. In addition, combustion of boreal forest materials produces smoke aerosol particles that are both oxygen-rich and chemically complex, yielding a carbonaceous aerosol matrix that is enriched in polar substances. As a consequence, emissions of carbonaceous smoke particles from large-scale combustion of boreal forest land may have a disproportionate effect on regional atmospheric chemistry and on cloud microphysical processes.

  20. Effect of oxidant concentration, exposure time, and seed particles on secondary organic aerosol chemical composition and yield

    DOE PAGES

    Lambe, A. T.; Chhabra, P. S.; Onasch, T. B.; ...

    2015-03-18

    We performed a systematic intercomparison study of the chemistry and yields of secondary organic aerosol (SOA) generated from OH oxidation of a common set of gas-phase precursors in a Potential Aerosol Mass (PAM) continuous flow reactor and several environmental chambers. In the flow reactor, SOA precursors were oxidized using OH concentrations ranging from 2.0 × 108 to 2.2 × 1010 molec cm-3 over exposure times of 100 s. In the environmental chambers, precursors were oxidized using OH concentrations ranging from 2 × 106 to 2 × 107 molec cm-3 over exposure times of several hours. The OH concentration in themore » chamber experiments is close to that found in the atmosphere, but the integrated OH exposure in the flow reactor can simulate atmospheric exposure times of multiple days compared to chamber exposure times of only a day or so. In most cases, for a specific SOA type the most-oxidized chamber SOA and the least-oxidized flow reactor SOA have similar mass spectra, oxygen-to-carbon and hydrogen-to-carbon ratios, and carbon oxidation states at integrated OH exposures between approximately 1 × 1011 and 2 × 1011 molec cm-3 s, or about 1–2 days of equivalent atmospheric oxidation. This observation suggests that in the range of available OH exposure overlap for the flow reactor and chambers, SOA elemental composition as measured by an aerosol mass spectrometer is similar whether the precursor is exposed to low OH concentrations over long exposure times or high OH concentrations over short exposure times. This similarity in turn suggests that both in the flow reactor and in chambers, SOA chemical composition at low OH exposure is governed primarily by gas-phase OH oxidation of the precursors rather than heterogeneous oxidation of the condensed particles. In general, SOA yields measured in the flow reactor are lower than measured in chambers for the range of equivalent OH exposures that can be measured in both the flow reactor and chambers. The influence of

  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. Apparatus for rapid measurement of aerosol bulk chemical composition

    DOEpatents

    Lee, Yin-Nan E.; Weber, Rodney J.

    2003-01-01

    An apparatus and method for continuous on-line measurement of chemical composition of aerosol particles with a fast time resolution are provided. The apparatus includes a modified particle size magnifier for producing activated aerosol particles and a collection device which collects the activated aerosol particles into a liquid stream for quantitative analysis by analytical methods. The method provided for on-line measurement of chemical composition of aerosol particles includes exposing aerosol carrying sample air to hot saturated steam thereby forming activated aerosol particles; collecting the activated aerosol particles by a collection device for delivery as a jet stream onto an impaction surface; flushing off the activated aerosol particles from the impaction surface into a liquid stream for delivery of the collected liquid stream to an analytical instrument for quantitative measurement.

  3. Apparatus for rapid measurement of aerosol bulk chemical composition

    DOEpatents

    Lee, Yin-Nan E.; Weber, Rodney J.; Orsini, Douglas

    2006-04-18

    An apparatus for continuous on-line measurement of chemical composition of aerosol particles with a fast time resolution is provided. The apparatus includes an enhanced particle size magnifier for producing activated aerosol particles and an enhanced collection device which collects the activated aerosol particles into a liquid stream for quantitative analysis by analytical means. Methods for on-line measurement of chemical composition of aerosol particles are also provided, the method including exposing aerosol carrying sample air to hot saturated steam thereby forming activated aerosol particles; collecting the activated aerosol particles by a collection device for delivery as a jet stream onto an impaction surface; and flushing off the activated aerosol particles from the impaction surface into a liquid stream for delivery of the collected liquid stream to an analytical instrument for quantitative measurement.

  4. Comparison of Aerosol Optical Depth from GOES Aerosol and Smoke Product (GASP) and MODIS to AERONET AOD and IMPROVE PM2.5 Mass at Bondville, Illinois Stratified by Chemical Composition, RH, Particle Size, and Season

    NASA Astrophysics Data System (ADS)

    Green, M. C.; Kondragunta, S.; Ciren, P.

    2008-05-01

    The USEPA is interested in using satellite remote sensing data to estimate levels of PM2.5. Here we report on comparisons of aerosol optical depth (AOD) from GOES Aerosol and Smoke Product (GASP) and the Moderate Resolution Imaging Spectroradiometer (MODIS) to IMPROVE network PM2.5 mass and AErosol RObotic NETwork (AERONET) ground-based AOD. Before we compare GASP and MODIS AOD to PM2.5, we first evaluate satellite AOD using the ground-based AERONET measurements and how it varies by aerosol chemical composition and size distribution. We focus attention on the Bondville, Illinois site because there is collocated IMPROVE sampling and an AERONET site. GASP provides aerosol optical depth at 0.55 um using top of atmosphere visible channel radiance measured from GOES east and GOES west. Time resolution is typically every 30 minutes during daylight hours. MODIS provides typically once per day AOD for any given location. The IMPROVE sampler provides a 24-hour integrated sample of PM10 mass, and PM2.5 mass and elemental composition on a one day in three schedule. AERONET provides aerosol optical depth at multiple wavelengths and aerosol size distribution as well as other derived parameters such as Angstrom exponent from ground based daytime measurements. We stratified cases by RH group, major chemical component, size distribution, and season. GOES AOD correlated best with PM2.5 mass during periods with mainly small particles, moderate RH, and sulfate dominated aerosol. It correlated poorly when RH is very high or low, aerosol is primarily organic, and when coarse to fine mass ratio is high. GASP AOD also correlated best with AERONET AOD when particles are mainly fine, suggesting the aerosol model assumptions (e.g. size distribution) may need to be varied geographically for GASP to achieve better AOD results.

  5. Ice nucleation, shape, and composition of aerosol particles in one of the most polluted cities in the world: Ulaanbaatar, Mongolia

    NASA Astrophysics Data System (ADS)

    Hasenkopf, Christa A.; Veghte, Daniel P.; Schill, Gregory P.; Lodoysamba, Sereeter; Freedman, Miriam Arak; Tolbert, Margaret A.

    2016-08-01

    Air pollution is attributable to 7 million deaths per year, or one out of every eight deaths globally. In particular, high concentrations of particulate matter (PM), a major air pollutant, have significant impacts on health and regional climate in urban centers. Many of the most polluted places, largely in developing countries, go severely understudied. Additionally, high particulate matter levels can have an impact on the microphysical properties of clouds, impacting precipitation and regional climate. Semi-arid regions can be especially affected by small changes in precipitation. Here we characterize the physical and chemical properties of PM in one of the most PM-polluted cities in the world: Ulaanbaatar, Mongolia, a semi-arid region in central Asia. Twice monthly aerosol samples were collected over 10 months from a central location and analyzed for composition and ice nucleation activity. Almost all particles collected were inhalable, consisting primarily of mineral dust, soot, and sulfate-organic. In winter, all classes of PM increase in concentration, with increased sulfur concentrations, and the particles are less active towards heterogeneous ice nucleation. In addition, concurrent monthly average PM10, SO2, NOx, and O3 levels and meteorological data at a nearby location are reported and made publicly available. These measurements provide an unprecedented seasonal characterization of the size, shape, chemical structure, and ice nucleating activity of PM data from Ulaanbaatar. This 10-month field study, exploring a variety of aerosol properties in Ulaanbaatar, Mongolia, is one of very few such studies conducted in the region or in such a highly polluted environment. The results of this study may inform work done in other similarly situated and polluted cities in Asia and elsewhere.

  6. 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.

  7. Measuring the temporal evolution of aerosol composition in a remote marine environment influenced by Saharan dust outflow using a new single particle mass spectrometer.

    NASA Astrophysics Data System (ADS)

    Marsden, Nicholas; Williams, Paul; Flynn, Michael; Taylor, Jonathan; Liu, Dantong; Allan, James; Coe, Hugh

    2016-04-01

    Refractory material constitutes a significant fraction of the atmospheric aerosol burden and has a strong influence on climate through the direct radiative effect and aerosol-cloud interactions, particularly in cold and mixed phase clouds. Composition of refractory aerosols is traditionally measured using off-line analytical techniques such as filter analyses. However, when using off-line techniques the temporal evolution of the data set is lost, meaning the measurements are difficult to relate to atmospheric processes. Recently, single particle mass spectrometry (SPMS) has proven a useful tool for the on-line study of refractory aerosols with the ability to probe size resolved chemical composition with high temporal resolution on a particle by particle basis. A new Laser Ablation Aerosol Time-of-Flight (LAAP-TOF) SPMS instrument with a modified optical detection system was deployed for ground based measurements at Praia, Cape Verde during the Ice in Cloud - Dust (ICE-D) multi-platform campaign in August 2015. A primary aim of the project was to evaluate the impact of Saharan dust on ice nucleation in mixed phase clouds. The instrument was operated over a 16 day period in which several hundred thousand single particle mass spectra were obtained from air masses with back trajectories traversing the Mid-Atlantic, Sahara Desert and West Africa. The data presented indicate external mixtures of sea salt and silicate mineral dust internally mixed with secondary species that are consistent with long range transport to a remote marine environment. The composition and size distributions measured with the LAAP-TOF are compared with measurements from an aerodynamic particle sizer (APS), Single Particle Soot Photometer (SP2), and data from SEM-EDX analysis of filter samples. The particle number fraction identified as silicate mineral from the mass spectra correlates with a fraction of the incandescent particles measured with the SP2. We discuss the suitability of the modified

  8. 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.

  9. Mixing state, composition, and sources of fine aerosol particles in the Qinghai-Tibetan Plateau and the influence of agricultural biomass burning

    NASA Astrophysics Data System (ADS)

    Li, W. J.; Chen, S. R.; Xu, Y. S.; Guo, X. C.; Sun, Y. L.; Yang, X. Y.; Wang, Z. F.; Zhao, X. D.; Chen, J. M.; Wang, W. X.

    2015-09-01

    Transmission electron microscopy (TEM) was employed to obtain morphology, size, composition, and mixing state of background fine particles with diameter less than 1 μm in the Qinghai-Tibetan Plateau (QTP) during 15 September to 15 October 2013. Individual aerosol particles mainly contained secondary inorganic aerosols (SIA-sulfate and nitrate) and organics during clean periods (PM2.5: particles less than 2.5 μg m-3). The presence of KCl-NaCl associated with organics and an increase of soot particles suggest that an intense biomass burning event caused the highest PM2.5 concentrations (> 30 μg m-3) during the study. A large number fraction of the fly ash-containing particles (21.73 %) suggests that coal combustion emissions in the QTP significantly contributed to air pollutants at the median pollution level (PM2.5: 10-30 μg m-3). We concluded that emissions from biomass burning and from coal combustion both constantly contribute to anthropogenic particles in the QTP atmosphere. Based on size distributions of individual particles in different pollution levels, we found that gas condensation on existing particles is an important chemical process for the formation of SIA with organic coating. TEM observations show that refractory aerosols (e.g., soot, fly ash, and visible organic particles) likely adhere to the surface of SIA particles larger than 200 nm due to coagulation. Organic coating and soot on surface of the aged particles likely influence their hygroscopic and optical properties in the QTP, respectively. To our knowledge, this study reports the first microscopic analysis of fine particles in the background QTP air.

  10. Physical properties, chemical composition, sources, spatial distribution and sinks of indoor aerosol particles in a university lecture hall

    NASA Astrophysics Data System (ADS)

    Salma, I.; Dosztály, K.; Borsós, T.; Söveges, B.; Weidinger, T.; Kristóf, G.; Péter, N.; Kertész, Zs.

    2013-01-01

    PM10 mass, particle number (N) and CO2 concentrations, particle number size distributions and meteorological parameters were determined with high time resolution, and daily aerosol samples were collected in the PM10-2.0 and PM2.0 size fractions for chemical analysis in the middle of a university lecture hall for one week. Median concentrations for the PM10 mass and N of 15.3 μg m-3 and 3.7 × 103 cm-3, respectively were derived. The data are substantially smaller than the related outdoor levels or typical values for residences. There were considerable concentration differences for workdays, weekends and various lectures. Main sources of PM10 mass include the usage of chalk sticks for writing, wiping the blackboard, ordinary movements and actions of students and cleaning. High PM10 mass concentration levels up to 100 μg m-3 were realised for short time intervals after wiping the blackboard. The mass concentrations decreased rapidly after the emission source ceased to be active. Two classes of coarse particles were identified. General indoor dust particles exhibited a residence time of approximately 35 min, while the residence time for the chalk dust particles was approximately 20 min as lower estimates. Emission source rate for wiping the blackboard was estimated to be between 8 and 14 mg min-1. This represents a substantial emission rate but the source is active only up to 1 min. Suspension of the chalk (made mainly of gypsum) dust particles was confirmed by enrichment of Ca and S in the hall with respect to ambient urban aerosol. Contribution of ambient aerosol via the heating, ventilation and air conditioning (HVAC) facility was considerable for time intervals when the indoor sources of PM10 mass were not intensive. The HVAC facility introduces, however, the major amount of aerosol particles from the outdoors as far as their number concentration is regarded. Mean contribution of ultrafine particles to the total particle number was (69 ± 7)%, which is smaller

  11. Aerosol particles in the upper troposphere and lower stratosphere: Elemental composition and morphology of individual particles in northern midlatitudes

    NASA Astrophysics Data System (ADS)

    Sheridan, Patrick J.; Brock, Charles A.; Wilson, James C.

    1994-11-01

    Atmospheric particles were collected in the midlatitude upper troposphere (UT) and lower stratosphere (LS) by inetrial impaction for subsequent electron microscopy and individual particle element analysis. More than 97% of particles analyzed on impactor substrates exposed in the LS contained only O and S in detectable quantities; these particles are believed to be acidic sulfate. Nonsulfate materials seen in the remaining particles included soot, other c-rich substances and crustal materials. Although not predominantly sulfate, usually carried a sulfer-rich coating in the LS. Samples collected very near and just below the tropopause were also dominated by sulfates. The fraction of sulfate particles analyzed on impactor substrates exposed in the UT was 91-94% of the total particle concentration. Nonsulfate substances observed in the UT samples included crustal-type material, hydrated marine salts, carbon-rich materials of several types, and metal-containing substances of uncertain origin. Most of these UT particles were not coated with detectable quantitites of sulfate.

  12. 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.

  13. Phase transition behaviour of sodium oleate aerosol particles

    NASA Astrophysics Data System (ADS)

    Nájera, Juan J.

    Field measurements have shown that organic surfactants are significant components of atmospheric aerosols. While fatty acids, among other surfactants, are prevalent in the atmosphere, the influence of these species on the chemical and physical properties of atmospheric aerosols remains not fully characterized. In order to assess the phase in which particles may exist, a detailed study of the deliquescence of a model surfactant aerosol has been carried out. Sodium oleate was chosen as a surfactant proxy relevant in atmospheric aerosol. Sodium oleate micelle aerosol particles were generated nebulizing a sodium oleate aqueous solution. In this study, the water uptake and phase transition of sodium oleate aerosol particles have been studied in a room temperature aerosol flow tube system (AFT) using Fourier transform infrared (FTIR) spectroscopy. Aerosol morphology and elemental composition were also analysed using scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDX) techniques. The particles are homogeneously distributed as ellipsoidal-shape aggregates of micelles particles with an average size of ˜1.1 μm. The deliquescence by the sodium oleate aerosol particles was monitored by infrared extinction spectroscopy, where the dried aerosol particles were exposed to increasing relative humidity as they passed through the AFT. Observations of the infrared absorption features of condensed phase liquid water enable to determine the sodium oleate deliquescence phase transition at 88±2%.

  14. 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

  15. 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.

  16. Ion composition of coarse and fine particles in Iasi, north-eastern Romania: Implications for aerosols chemistry in the area

    NASA Astrophysics Data System (ADS)

    Arsene, Cecilia; Olariu, Romeo Iulian; Zarmpas, Pavlos; Kanakidou, Maria; Mihalopoulos, Nikolaos

    2011-02-01

    Atmospheric loadings of the aerosols coarse (particles of AED > 1.5 μm) and fine fractions (particles of AED < 1.5 μm) were determined in Iasi, north-eastern Romania from January 2007 to March 2008. Concentrations of water soluble ions (SO 42-, NO 3-, Cl -, C 2O 42-, NH 4+, K +, Na +, Ca 2+ and Mg 2+) were measured using ion chromatography (IC). In the coarse particles, calcium and carbonate are the main ionic constituents (˜65%), whereas in the fine particles SO 42-, NO 3-, Cl - and NH 4+ are the most abundant. Temperature and relative humidity (RH) associated with increased concentrations of specific ions might be the main factors controlling the aerosol chemistry at the investigated site. From August 2007 to March 2008 high RH (as high as 80% for about 82% of the investigated period) was prevailing in Iasi and the collected particles were expected to have deliquesced and form an internal mixture. We found that in fine particles ammonium nitrate (NH 4NO 3) is important especially under conditions of NH 4+/SO 42- ratio higher than 1.5 and high RH (RH above deliquescence of NH 4Cl, NH 4NO 3 and (NH 4) 2SO 4). At the investigated site large ammonium artifacts may occur due to inter-particle interaction especially under favorable meteorological conditions. A methodology for estimating the artifact free ambient ammonium concentration is proposed for filter pack sampling data of deliquesced particles. Nitrate and sulfate ions in coarse particles are probably formed via reactions of nitric and sulfuric acid with calcium carbonate and sodium chloride which during specific seasons are abundant at the investigated site. In the fine mode sulfate concentration maximized during summer (due to enhanced photochemistry) and winter (due to high concentration of SO 2 emitted from coal burning). Natural contributions, dust or sea-salt related, prevail mainly in the coarse particles. From May 2007 to August 2007, when air masses originated mainly from Black Sea, in the coarse

  17. Rapid Measurements of Aerosol Ionic Composition and 3-10 nm Particle Size Distributions On The NASA P3 To Better Quantify Processes Affecting Aerosols Advected From East Asia

    NASA Technical Reports Server (NTRS)

    Weber, Rodney J.

    2004-01-01

    The Particle Into Liquid Sample (PILS) was deployed on the NASA P3 for airborne measurements of fine particle ionic chemical composition. The data have been quality assured and reside in the NASA data archive. We have analyzed our data to characterize the sources and atmospheric processing of fine aerosol particles advected from the region during the experiments. Fine particle water-soluble potassium was found to serve as a useful aerosol tracer for biomass smoke. Ratios of PILS potassium to sulfate are used as a means of estimating the percent contribution of biomass burning to fine particle mass in mixed plumes advecting from Asia. The high correlations between K+ and NO3(sup -) and NH4(sup +)' indicated that biomass burning was a significant source of these aerosol compounds in the region. It is noteworthy that the air mass containing the highest concentrations of fine particles recorded in all of ACE-Asia and TRACE-P appeared to be advecting from the Bejing/Tientsin urban region and also had the highest K(+), NO3(sup -) and NH4(sup +) concentrations of both studies. Based on K+/SO4(sup 2-) ratio's, we estimated that the plume was composed of approx. 60% biomass burning emissions, possibly from the use of bio-fuels in the urban regions.

  18. Nozzles for Focusing Aerosol Particles

    DTIC Science & Technology

    2009-10-01

    control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE ( DD -MM-YYYY) October 2009 2. REPORT TYPE Final 3. DATES...Figures Figure 1. The design of the first-generation aerodynamic focusing nozzle for aerosol particles used for SPFS and TAOS instrument prototypes...Some nozzles were fabricated in aluminum and some in steel. It has been used for SPFS and TAOS measurement technologies both in the laboratory and

  19. 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.

  20. The effect of local sources on particle size and chemical composition and their role in aerosol-cloud interactions at Puijo measurement station

    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.

    2014-06-01

    Interactions between aerosols and liquid water clouds were studied during autumns 2010-2011 at a semiurban measurement station on Puijo tower in Kuopio, Finland. Cloud interstitial and total aerosol size distributions, particle chemical composition and hygroscopicity and cloud droplet size distribution were measured, with a focus on comparing clean air masses with those affected by local sources. On average, the polluted air contained more particles than the clean air masses, and generally the concentrations decreased during cloud events. Cloud processing was found to take place, especially in the clean air masses, and to a lesser extent in the polluted air. Some, mostly minor, differences in the average 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, with a special focus on the emissions from local sources, including a paper mill and a heating plant. This revealed larger variations in particle and cloud properties than the analysis of the whole data set. Clear differences in the total (between 214 and 2200 cm-3) and accumulation mode particle concentrations (between 62 and 169 cm-3) were observed. Particle chemical composition, especially the concentrations of organics (between 0.42 and 1.28 μg m-3) and sulfate (between 0.16 and 4.43 μg m-3), varied considerably. This affected the hygroscopic growth factor: for example, for 100 nm particles the range was from 1.21 to 1.45 at 90% relative humidity. Particularly, large particles, high hygroscopicities and elevated amounts of inorganics were linked with the pollutant plumes. Moreover, the particle hygroscopicity distributions in the polluted air were clearly bimodal, indicating externally mixed aerosol. The variable conditions also had an impact on cloud droplet

  1. Subarctic atmospheric aerosol composition: 1. Ambient aerosol characterization

    SciTech Connect

    Friedman, Beth; Herich, Hanna; Kammermann, Lukas; Gross, Deborah S.; Ameth, Almut; Holst, Thomas; Lohmann, U.; Cziczo, Daniel J.

    2009-07-10

    Sub-Arctic aerosol was sampled during July 2007 at the Abisko Research Station Stordalen field site operated by the Royal Swedish Academy of Sciences. Located in northern Sweden at 68º latitude and 385 meters above sea level (msl), this site is classified as a semi-continuous permafrost mire. Number density, size distribution, cloud condensation nucleus properties, and chemical composition of the ambient aerosol were determined. Backtrajectories showed that three distinct airmasses were present over Stordalen during the sampling period. Aerosol properties changed and correlated with airmass origin to the south, northeast, or west. We observe that Arctic aerosol is not compositionally unlike that found in the free troposphere at mid-latitudes. Internal mixtures of sulfates and organics, many on insoluble biomass burning and/or elemental carbon cores, dominate the number density of particles from ~200 to 2000 nm aerodynamic diameter. Mineral dust which had taken up gas phase species was observed in all airmasses. Sea salt, and the extent to which it had lost volatile components, was the aerosol type that most varied with airmass.

  2. 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.

  3. The relationship between aerosol particles chemical composition and optical properties to identify the biomass burning contribution to fine particles concentration: a case study for São Paulo city, Brazil.

    PubMed

    de Miranda, Regina Maura; Lopes, Fabio; do Rosário, Nilton Évora; Yamasoe, Marcia Akemi; Landulfo, Eduardo; de Fatima Andrade, Maria

    2016-12-01

    The air quality in the Metropolitan Area of São Paulo (MASP) is primarily determined by the local pollution source contribution, mainly the vehicular fleet, but there is a concern about the role of remote sources to the fine mode particles (PM2.5) concentration and composition. One of the most important remote sources of atmospheric aerosol is the biomass burning emissions from São Paulo state's inland and from the central and north portions of Brazil. This study presents a synergy of different measurements of atmospheric aerosol chemistry and optical properties in the MASP in order to show how they can be used as a tool to identify particles from local and remote sources. For the clear identification of the local and remote source contribution, aerosol properties measurements at surface level were combined with vertical profiles information. Over 15 days in the austral winter of 2012, particulate matter (PM) was collected using a cascade impactor and a Partisol sampler in São Paulo City. Mass concentrations were determined by gravimetry, black carbon concentrations by reflectance, and trace element concentrations by X-ray fluorescence. Aerosol optical properties were studied using a multifilter rotating shadowband radiometer (MFRSR), a Lidar system and satellite data. Optical properties, concentrations, size distributions, and elemental composition of atmospheric particles were strongly related and varied according to meteorological conditions. During the sampling period, PM mean mass concentrations were 17.4 ± 10.1 and 15.3 ± 6.9 μg/m(3) for the fine and coarse fractions, respectively. The mean aerosol optical depths at 415 nm and Ångström exponent (AE) over the whole period were 0.29 ± 0.14 and 1.35 ± 0.11, respectively. Lidar ratios reached values of 75 sr. The analyses of the impacts of an event of biomass burning smoke transport to the São Paulo city revealed significant changing on local aerosol concentrations and optical parameters

  4. Long-term real-time measurements of aerosol particle composition in Beijing, China: seasonal variations, meteorological effects, and source analysis

    NASA Astrophysics Data System (ADS)

    Sun, Y. L.; Wang, Z. F.; Du, W.; Zhang, Q.; Wang, Q. Q.; Fu, P. Q.; Pan, X. L.; Li, J.; Jayne, J.; Worsnop, D. R.

    2015-09-01

    High concentrations of fine particles (PM2.5) are frequently observed during all seasons in Beijing, China, leading to severe air pollution and human health problems in this megacity. In this study, we conducted real-time measurements of non-refractory submicron aerosol (NR-PM1) species (sulfate, nitrate, ammonium, chloride, and organics) in Beijing using an Aerodyne Aerosol Chemical Speciation Monitor for 1 year, from July 2011 to June 2012. This is the first long-term, highly time-resolved (~ 15 min) measurement of fine particle composition in China. The seasonal average (±1σ) mass concentration of NR-PM1 ranged from 52 (±49) μg m-3 in the spring season to 62 (±49) μg m-3 in the summer season, with organics being the major fraction (40-51 %), followed by nitrate (17-25 %) and sulfate (12-17 %). Organics and chloride showed pronounced seasonal variations, with much higher concentrations in winter than in the other seasons, due to enhanced coal combustion emissions. Although the seasonal variations of secondary inorganic aerosol (SIA, i.e., sulfate + nitrate + ammonium) concentrations were not significant, higher contributions of SIA were observed in summer (57-61 %) than in winter (43-46 %), indicating that secondary aerosol production is a more important process than primary emissions in summer. Organics presented pronounced diurnal cycles that were similar among all seasons, whereas the diurnal variations of nitrate were mainly due to the competition between photochemical production and gas-particle partitioning. Our data also indicate that high concentrations of NR-PM1 (> 60 μg m-3) are usually associated with high ambient relative humidity (RH) (> 50 %) and that severe particulate pollution is characterized by different aerosol composition in different seasons. All NR-PM1 species showed evident concentration gradients as a function of wind direction, generally with higher values associated with wind from the south, southeast or east. This was consistent

  5. The optical manipulation and characterisation of aerosol particles

    NASA Astrophysics Data System (ADS)

    Reid, Jonathan P.

    2008-08-01

    Aerosols play a crucial role in many areas of science, ranging from atmospheric chemistry and physics, to pharmaceutical aerosols and drug delivery to the lungs, to combustion science and spray drying. The development of new methods for characterising the properties and dynamics of aerosol particles is of crucial importance if the complex role that particles play is to be more fully understood. Optical tweezers provide a valuable new tool to address fundamental questions in aerosol science. Single or multiple particles 1-15 μm in diameter can be manipulated for indefinite timescales. Linear and non-linear Raman and fluorescence spectroscopies can be used to probe particle composition, phase, component mixing state, and size. In particular, size can be determined with nanometre accuracy, allowing accurate measurements of the thermodynamic properties of aerosols, the kinetics of particle transformation and of light absorption. Further, the simultaneous manipulation of multiple particles in parallel optical traps provides a method for performing comparative measurements on particles of different composition. We will present some latest work in which optical tweezers are used to characterise aerosol dynamics, demonstrating that optical tweezers can find application in studies of hygroscopicity, the mixing state of different chemical components, including the phase separation of immiscible phases, and the kinetics of chemical transformation.

  6. A novel method for online analysis of gas and particle composition: description and evaluation of a Filter Inlet for Gases and AEROsols (FIGAERO)

    NASA Astrophysics Data System (ADS)

    Lopez-Hilfiker, F. D.; Mohr, C.; Ehn, M.; Rubach, F.; Kleist, E.; Wildt, J.; Mentel, Th. F.; Lutz, A.; Hallquist, M.; Worsnop, D.; Thornton, J. A.

    2014-04-01

    We describe a novel inlet that allows measurement of both gas and particle molecular composition when coupled to mass spectrometric, chromatographic, or optical sensors: the Filter Inlet for Gases and AEROsols (FIGAERO). The design goals for the FIGAERO are to allow unperturbed observation of ambient air while simultaneously analyzing gases and collecting particulate matter on a Teflon® (hereafter Teflon) filter via an entirely separate sampling port. The filter is analyzed periodically by the same sensor on hourly or faster timescales using temperature-programmed thermal desorption. We assess the performance of the FIGAERO by coupling it to a high-resolution time-of-flight chemical-ionization mass spectrometer (HRToF-CIMS) in laboratory chamber studies of α-pinene oxidation and field measurements at a boreal forest location. Low instrument backgrounds give detection limits of ppt or lower for compounds in the gas-phase and in the picogram m-3 range for particle phase compounds. The FIGAERO-HRToF-CIMS provides molecular information about both gases and particle composition on the 1 Hz and hourly timescales, respectively for hundreds of compounds. The FIGAERO thermal desorptions are highly reproducible (better than 10%), allowing a calibrated assessment of the effective volatility of desorbing compounds and the role of thermal decomposition during the desorption process. We show that the often multi-modal desorption thermograms arising from secondary organic aerosol (SOA) provide additional insights into molecular composition and/or particle morphology, and exhibit changes with changes in SOA formation or aging pathways.

  7. Chemical composition, microstructure, and hygroscopic properties of aerosol particles at the Zotino Tall Tower Observatory (ZOTTO), Siberia, during a summer campaign

    DOE PAGES

    Mikhailov, E. F.; Mironov, G. N.; Pöhlker, C.; ...

    2015-03-16

    In this study we describe the hygroscopic properties of accumulation- and coarse-mode aerosol particles sampled at the Zotino Tall Tower Observatory (ZOTTO) in Central Siberia (61° N; 89° E) from 16 to 21 June 2013. The hygroscopic growth measurements were supplemented with chemical analyses of the samples, including inorganic ions and organic/elemental carbon. In addition, the microstructure and chemical composition of aerosol particles were analyzed by X-ray micro-spectroscopy (STXM-NEXAFS) and transmission electron microscopy (TEM). A mass closure analysis indicates that organic carbon accounted for 61 and 38% of PM in the accumulation mode and coarse mode, respectively. The water solublemore » fraction of organic matter was estimated to be 52 and 8% of PM in these modes. Sulfate, predominantly in the form of ammoniated sulfate, was the dominant inorganic component in both size modes: ~ 34% in the accumulation vs. ~ 47% in the coarse mode. The hygroscopic growth measurements were conducted with a filter-based differential hygroscopicity analyzer (FDHA) over the range of 5–99.4% RH in the hydration and dehydration operation modes. The FDHA study indicates that both accumulation and coarse modes exhibit pronounced water uptake approximately at the same RH, starting at ~ 70%, while efflorescence occurred at different humidities, i.e., at ~ 35% RH for submicron particles vs. ~ 50% RH for supermicron particles. This ~ 15% RH difference was attributed to higher content of organic material in the submicron particles, which suppresses water release in the dehydration experiments. The kappa mass interaction model (KIM) was applied to characterize and parameterize non-ideal solution behavior and concentration-dependent water uptake by atmospheric aerosol samples in the 5–99.4% RH range. Based on KIM, the volume-based hygroscopicity parameter, κv, was calculated. The κv, ws value related to the water soluble (ws) fraction was estimated to be ~ 0.15 for the

  8. Chemical composition, microstructure, and hygroscopic properties of aerosol particles at the Zotino Tall Tower Observatory (ZOTTO), Siberia, during a summer campaign

    NASA Astrophysics Data System (ADS)

    Mikhailov, E. F.; Mironov, G. N.; Pöhlker, C.; Chi, X.; Krüger, M. L.; Shiraiwa, M.; Förster, J.-D.; Pöschl, U.; Vlasenko, S. S.; Ryshkevich, T. I.; Weigand, M.; Kilcoyne, A. L. D.; Andreae, M. O.

    2015-08-01

    In this study we describe the hygroscopic properties of accumulation- and coarse-mode aerosol particles sampled at the Zotino Tall Tower Observatory (ZOTTO) in central Siberia (61° N, 89° E) from 16 to 21 June 2013. The hygroscopic growth measurements were supplemented with chemical analyses of the samples, including inorganic ions and organic/elemental carbon. In addition, the microstructure and chemical compositions of aerosol particles were analyzed by x-ray micro-spectroscopy (STXM-NEXAFS) and transmission electron microscopy (TEM). A mass closure analysis indicates that organic carbon accounted for 61 and 38 % of particulate matter (PM) in the accumulation mode and coarse mode, respectively. The water-soluble fraction of organic matter was estimated to be 52 and 8 % of PM in these modes. Sulfate, predominantly in the form of ammoniated sulfate, was the dominant inorganic component in both size modes: ~ 34 % in the accumulation mode vs. ~ 47 % in the coarse mode. The hygroscopic growth measurements were conducted with a filter-based differential hygroscopicity analyzer (FDHA) over the range of 5-99.4 % RH in the hydration and dehydration operation modes. The FDHA study indicates that both accumulation and coarse modes exhibit pronounced water uptake approximately at the same relative humidity (RH), starting at ~ 70 %, while efflorescence occurred at different humidities, i.e., at ~ 35 % RH for submicron particles vs. ~ 50 % RH for supermicron particles. This ~ 15 % RH difference was attributed to higher content of organic material in the submicron particles, which suppresses water release in the dehydration experiments. The kappa mass interaction model (KIM) was applied to characterize and parameterize non-ideal solution behavior and concentration-dependent water uptake by atmospheric aerosol samples in the 5-99.4 % RH range. Based on KIM, the volume-based hygroscopicity parameter, κv, was calculated. The κv,ws value related to the water-soluble (ws

  9. Chemical composition, microstructure, and hygroscopic properties of aerosol particles at the Zotino Tall Tower Observatory (ZOTTO), Siberia, during a summer campaign

    NASA Astrophysics Data System (ADS)

    Mikhailov, E. F.; Mironov, G. N.; Pöhlker, C.; Chi, X.; Krüger, M. L.; Shiraiwa, M.; Förster, J.-D.; Pöschl, U.; Vlasenko, S. S.; Ryshkevich, T. I.; Weigand, M.; Kilcoyne, A. L. D.; Andreae, M. O.

    2015-03-01

    In this study we describe the hygroscopic properties of accumulation- and coarse-mode aerosol particles sampled at the Zotino Tall Tower Observatory (ZOTTO) in Central Siberia (61° N; 89° E) from 16 to 21 June 2013. The hygroscopic growth measurements were supplemented with chemical analyses of the samples, including inorganic ions and organic/elemental carbon. In addition, the microstructure and chemical composition of aerosol particles were analyzed by X-ray micro-spectroscopy (STXM-NEXAFS) and transmission electron microscopy (TEM). A mass closure analysis indicates that organic carbon accounted for 61 and 38% of PM in the accumulation mode and coarse mode, respectively. The water soluble fraction of organic matter was estimated to be 52 and 8% of PM in these modes. Sulfate, predominantly in the form of ammoniated sulfate, was the dominant inorganic component in both size modes: ∼34% in the accumulation vs. ∼47% in the coarse mode. The hygroscopic growth measurements were conducted with a filter-based differential hygroscopicity analyzer (FDHA) over the range of 5-99.4% RH in the hydration and dehydration operation modes. The FDHA study indicates that both accumulation and coarse modes exhibit pronounced water uptake approximately at the same RH, starting at ∼70%, while efflorescence occurred at different humidities, i.e., at ∼35% RH for submicron particles vs. ∼50% RH for supermicron particles. This ∼15% RH difference was attributed to higher content of organic material in the submicron particles, which suppresses water release in the dehydration experiments. The kappa mass interaction model (KIM) was applied to characterize and parameterize non-ideal solution behavior and concentration-dependent water uptake by atmospheric aerosol samples in the 5-99.4% RH range. Based on KIM, the volume-based hygroscopicity parameter, κv, was calculated. The κv, ws value related to the water soluble (ws) fraction was estimated to be ∼0.15 for

  10. Particle-resolved simulation of aerosol size, composition, mixing state, and the associated optical and cloud condensation nuclei activation properties in an evolving urban plume

    SciTech Connect

    Zaveri, Rahul A.; Barnard, James C.; Easter, Richard C.; Riemer, Nicole; West, Matthew

    2010-09-11

    The recently developed particle-resolved aerosol box model PartMC-MOSAIC was used to simulate the evolution of aerosol mixing state and the associated optical and cloud condensation nuclei (CCN) activation properties in an idealized urban plume. The model explicitly resolved the size and composition of individual particles from a number of sources and tracked their evolution due to condensation/evaporation, coagulation, emission, and dilution. The ensemble black carbon (BC) specific absorption cross section increased by 40% over the course of two days as a result of BC aging by condensation and coagulation. Three- and four-fold enhancements in CCN/CN ratios were predicted to occur within 6 hours for 0.2% and 0.5% supersaturations (S), respectively. The particle-resolved results were used to evaluate the errors in the optical and CCN activation properties that would be predicted by a conventional sectional framework that assumes monodisperse, internally-mixed particles within each bin. This assumption artificially increased the ensemble BC specific absorption by 14-30% and decreased the single scattering albedo by 0.03-0.07 while the bin resolution had a negligible effect. In contrast, the errors in CCN/CN ratios were sensitive to the bin resolution, and they depended on the chosen supersaturation. For S = 0.2%, the CCN/CN ratio predicted using 100 internally-mixed bins was up to 25% higher than the particle-resolved results, while it was up to 125% higher using 10 internally-mixed bins. Errors introduced in the predicted optical and CCN properties by neglecting coagulation were also quantified.

  11. Change in global aerosol composition since preindustrial times

    NASA Astrophysics Data System (ADS)

    Tsigaridis, K.; Krol, M.; Dentener, F. J.; Balkanski, Y.; Lathière, J.; Metzger, S.; Hauglustaine, D. A.; Kanakidou, M.

    2006-06-01

    To elucidate human induced changes of aerosol load and composition in the atmosphere, a coupled aerosol and gas-phase chemistry transport model of the troposphere and lower stratosphere has been used. This is the first 3-d modeling study that focuses on aerosol chemical composition change since preindustrial times considering the secondary organic aerosol formation together with all other main aerosol components including nitrate. In particular, we evaluate non-sea-salt sulfate (nss-SO4=), ammonium (NH4+), nitrate (NO3-), black carbon (BC), sea-salt, dust, primary and secondary organics (POA and SOA) with a focus on the importance of secondary organic aerosols. Our calculations show that the aerosol optical depth (AOD) has increased by about 21% since preindustrial times. This enhancement of AOD is attributed to a rise in the atmospheric load of BC, nss-SO4=, NO3-, POA and SOA by factors of 3.3, 2.6, 2.7, 2.3 and 1.2, respectively, whereas we assumed that the natural dust and sea-salt sources remained constant. The nowadays increase in carbonaceous aerosol loading is dampened by a 34-42% faster conversion of hydrophobic to hydrophilic carbonaceous aerosol leading to higher removal rates. These changes between the various aerosol components resulted in significant modifications of the aerosol chemical composition. The relative importance of the various aerosol components is critical for the aerosol climatic effect, since atmospheric aerosols behave differently when their chemical composition changes. According to this study, the aerosol composition changed significantly over the different continents and with height since preindustrial times. The presence of anthropogenically emitted primary particles in the atmosphere facilitates the condensation of the semi-volatile species that form SOA onto the aerosol phase, particularly in the boundary layer. The SOA burden that is dominated by the natural component has increased by 24% while its contribution to the AOD has

  12. Change in global aerosol composition since preindustrial times

    NASA Astrophysics Data System (ADS)

    Tsigaridis, K.; Krol, M.; Dentener, F. J.; Balkanski, Y.; Lathière, J.; Metzger, S.; Hauglustaine, D. A.; Kanakidou, M.

    2006-11-01

    To elucidate human induced changes of aerosol load and composition in the atmosphere, a coupled aerosol and gas-phase chemistry transport model of the troposphere and lower stratosphere has been used. The present 3-D modeling study focuses on aerosol chemical composition change since preindustrial times considering the secondary organic aerosol formation together with all other main aerosol components including nitrate. In particular, we evaluate non-sea-salt sulfate (nss-SO4=), ammonium (NH4+), nitrate (NO3-), black carbon (BC), sea-salt, dust, primary and secondary organics (POA and SOA) with a focus on the importance of secondary organic aerosols. Our calculations show that the aerosol optical depth (AOD) has increased by about 21% since preindustrial times. This enhancement of AOD is attributed to a rise in the atmospheric load of BC, nss-SO4=, NO3aerosol loading is dampened by a 34-42% faster conversion of hydrophobic to hydrophilic carbonaceous aerosol leading to higher removal rates. These changes between the various aerosol components resulted in significant modifications of the aerosol chemical composition. The relative importance of the various aerosol components is critical for the aerosol climatic effect, since atmospheric aerosols behave differently when their chemical composition changes. According to this study, the aerosol composition changed significantly over the different continents and with height since preindustrial times. The presence of anthropogenically emitted primary particles in the atmosphere facilitates the condensation of the semi-volatile species that form SOA onto the aerosol phase, particularly in the boundary layer. The SOA burden that is dominated by the natural component has increased by 24% while its contribution to the AOD has increased

  13. 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.

  14. 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

  15. 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

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

    SciTech Connect

    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.

  17. Aerosol particles collected on aircraft flights over the northwestern Pacific region during the ACE-Asia campaign: Composition and major sources of the organic compounds

    NASA Astrophysics Data System (ADS)

    Simoneit, Bernd R. T.; Kobayashi, Minoru; Mochida, Michihiro; Kawamura, Kimitaka; Huebert, Barry J.

    2004-10-01

    Atmospheric particulate matter, collected over the polluted east Asia/Pacific region in spring 2001 during research flights with the National Center for Atmospheric Research (NCAR) C-130 aircraft, was analyzed for different types of organic compounds using capillary gas chromatography-mass spectrometry. More than 70 organic species were detected in the aerosols and grouped into different compound classes on the basis of functional groups, including n-alkanes, polycyclic aromatic hydrocarbons, fatty acids, dehydroabietic acid, alkanols, water-soluble sugars (including glucose, sucrose, mycose, and levoglucosan), monocarboxylic and dicarboxylic acids, urea, and phthalates. Interestingly, the water-soluble compounds (72-133 ng m-3) were found to account for 16-50% (average 34%) of the total identified compound mass (TCM). Organic compounds were further categorized into several groups to suggest their sources. Fossil fuel combustion was recognized as the most significant source for the TCM (contributing 33-80% of TCM, average 50%), followed by soil resuspension (5-25%, average 19%) and secondary oxidation products (4-15%, average 9%). In contrast, the contribution of natural sources such as terrestrial plant wax and marine lipids (fatty acids and alkanols) was relatively small (3.4% and 9.4% on average, respectively). Biomass burning was suggested to contribute only a minor portion to the TCM of the Asian aerosols during the spring season (1.4% on average based on levoglucosan). However, levoglucosan may have been hydrolyzed and/or oxidized in part during long-range transport, and therefore this value represents a lower limit. The organic compound compositions of these samples are very different from those reported for aerosol particles of the Atlantic Ocean and from the earlier data for the mid-Pacific in terms of the abundant presence of water-soluble compounds consisting of saccharides, anhydrosaccharides, and the secondary dicarboxylic acids. This study

  18. Direct shortwave forcing of climate by anthropogenic sulfate aerosol: Sensitivity to particle size, composition, and relative humidity

    SciTech Connect

    Nemesure, S.; Wagener, R.; Schwartz, S.E.

    1996-04-01

    Recent estimates of global or hemispheric average forcing of climate by anthropogenic sulfate aerosol due to scattering of shortwave radiation are uncertain by more than a factor of 2. This paper examines the sensitivity of forcing to these microphysical properties for the purposes of obtaining a better understanding of the properties required to reduce the uncertainty in the forcing.

  19. 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.

  20. Relating hygroscopicity and optical properties to chemical composition and structure of secondary organic aerosol particles generated from the ozonolysis of α-pinene

    NASA Astrophysics Data System (ADS)

    Denjean, C.; Formenti, P.; Picquet-Varrault, B.; Pangui, E.; Zapf, P.; Katrib, Y.; Giorio, C.; Tapparo, A.; Monod, A.; Temime-Roussel, B.; Decorse, P.; Mangeney, C.; Doussin, J. F.

    2015-03-01

    Secondary organic aerosol (SOA) were generated from the ozonolysis of α-pinene in the CESAM (French acronym for Experimental Multiphasic Atmospheric Simulation Chamber) simulation chamber. The SOA formation and aging were studied by following their optical, hygroscopic and chemical properties. The optical properties were investigated by determining the particle complex refractive index (CRI). The hygroscopicity was quantified by measuring the effect of relative humidity (RH) on the particle size (size growth factor, GF) and on the scattering coefficient (scattering growth factor, f(RH)). The oxygen to carbon atomic ratios (O : C) of the particle surface and bulk were used as a sensitive parameter to correlate the changes in hygroscopic and optical properties of the SOA composition during their formation and aging in CESAM. The real CRI at 525 nm wavelength decreased from 1.43-1.60 (±0.02) to 1.32-1.38 (±0.02) during the SOA formation. The decrease in the real CRI correlated to the O : C decrease from 0.68 (±0.20) to 0.55 (±0.16). In contrast, the GF remained roughly constant over the reaction time, with values of 1.02-1.07 (±0.02) at 90% (±4.2%) RH. Simultaneous measurements of O : C of the particle surface revealed that the SOA was not composed of a homogeneous mixture, but contained less oxidised species at the surface which may limit water absorption. In addition, an apparent change in both mobility diameter and scattering coefficient with increasing RH from 0 to 30% was observed for SOA after 14 h of reaction. We postulate that this change could be due to a change in the viscosity of the SOA from a predominantly glassy state to a predominantly liquid state.

  1. Mexico City aerosol analysis during MILAGRO using high resolution aerosol mass spectrometry at the urban supersite (T0) - Part 1: Fine particle composition and organic source apportionment

    SciTech Connect

    Aiken, A.C.; Wang, J.; Salcedo, D.; Cubison, M. J.; Huffman, J. A.; DeCarlo, P. F.; Ulbrich, I. M.; Docherty, K. S.; Sueper, D.; Kimmel, J. R.; Worsnop, D. R.; Trimborn, A.; Northway, M.; Stone, E. A.; Schauer, J. J.; Volkamer, R. M.; Fortner, E.; de Foy, B.; Laskin, A.; Shutthanandan, V.; Zheng, J.; Zhang, R.; Gaffney, J.; Marley, N. A.; Paredes-Miranda, G.; Arnott, W. P.; Molina, L. T.; Sosa, G.; Jimenez, J. L.

    2009-09-01

    Submicron aerosol was analyzed during the MILAGRO field campaign in March 2006 at the T0 urban supersite in Mexico City with a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and complementary instrumentation. Mass concentrations, diurnal cycles, and size distributions of inorganic and organic species are similar to results from the CENICA supersite in April 2003 with organic aerosol (OA) comprising about half of the fine PM mass. Positive Matrix Factorization (PMF) analysis of the high resolution OA spectra identified three major components: chemically-reduced urban primary emissions (hydrocarbon-like OA, HOA), oxygenated OA (OOA, mostly secondary OA or SOA), and biomass burning OA (BBOA) that correlates with levoglucosan and acetonitrile. BBOA includes several very large plumes from regional fires and likely also some refuse burning. A fourth OA component is a small local nitrogen-containing reduced OA component (LOA) which accounts for 9% of the OA mass but one third of the organic nitrogen, likely as amines. OOA accounts for almost half of the OA on average, consistent with previous observations. OA apportionment results from PMF-AMS are compared to the PM{sub 2.5} chemical mass balance of organic molecular markers (CMB-OMM, from GC/MS analysis of filters). Results from both methods are overall consistent. Both assign the major components of OA to primary urban, biomass burning/woodsmoke, and secondary sources at similar magnitudes. The 2006 Mexico City emissions inventory underestimates the urban primary PM{sub 2.5} emissions by a factor of {approx}4, and it is {approx}16 times lower than afternoon concentrations when secondary species are included. Additionally, the forest fire contribution is at least an order-of-magnitude larger than in the inventory.

  2. Chemical composition, microstructure, and hygroscopic properties of aerosol particles at the Zotino Tall Tower Observatory (ZOTTO), Siberia, during a summer campaign

    SciTech Connect

    Mikhailov, E. F.; Mironov, G. N.; Pöhlker, C.; Chi, X.; Krüger, M. L.; Shiraiwa, M.; Förster, J. -D.; Pöschl, U.; Vlasenko, S. S.; Ryshkevich, T. I.; Weigand, M.; Kilcoyne, A. L. D.; Andreae, M. O.

    2015-03-16

    In this study we describe the hygroscopic properties of accumulation- and coarse-mode aerosol particles sampled at the Zotino Tall Tower Observatory (ZOTTO) in Central Siberia (61° N; 89° E) from 16 to 21 June 2013. The hygroscopic growth measurements were supplemented with chemical analyses of the samples, including inorganic ions and organic/elemental carbon. In addition, the microstructure and chemical composition of aerosol particles were analyzed by X-ray micro-spectroscopy (STXM-NEXAFS) and transmission electron microscopy (TEM). A mass closure analysis indicates that organic carbon accounted for 61 and 38% of PM in the accumulation mode and coarse mode, respectively. The water soluble fraction of organic matter was estimated to be 52 and 8% of PM in these modes. Sulfate, predominantly in the form of ammoniated sulfate, was the dominant inorganic component in both size modes: ~ 34% in the accumulation vs. ~ 47% in the coarse mode.

    The hygroscopic growth measurements were conducted with a filter-based differential hygroscopicity analyzer (FDHA) over the range of 5–99.4% RH in the hydration and dehydration operation modes. The FDHA study indicates that both accumulation and coarse modes exhibit pronounced water uptake approximately at the same RH, starting at ~ 70%, while efflorescence occurred at different humidities, i.e., at ~ 35% RH for submicron particles vs. ~ 50% RH for supermicron particles. This ~ 15% RH difference was attributed to higher content of organic material in the submicron particles, which suppresses water release in the dehydration experiments.

    The kappa mass interaction model (KIM) was applied to characterize and parameterize non-ideal solution behavior and concentration-dependent water uptake by atmospheric aerosol samples in the 5–99.4% RH range. Based on KIM, the volume-based hygroscopicity parameter, κv, was calculated. The κv, ws value related to the water soluble (ws) fraction was

  3. 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.

  4. 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.

  5. Aerosol Composition and Morphology during the 2005 Marine Stratus Radiation Aerosol and Drizzle Study

    SciTech Connect

    Berkowitz, Carl M.; Jobson, B Tom T.; Alexander, M. Lizabeth; Laskin, Alexander; Laulainen, Nels S.

    2005-12-01

    The composition and morphology of aerosols activated within cloud droplets relative to the properties of aerosols not activated is of central importance to studies directed at improved parameterization of the treatment of aerosols in large-scale models. These models have many applications, including evaluations of the impact of anthropogenic aerosols on climate. To further our understanding of these aerosol characteristics, scientists from the U.S. Department of Energy Atmospheric Science Program (ASP), joined forces with other participants of the Atmospheric Radiation Measurement (ARM) "Marine Stratus Radiation Aerosol and Drizzle Study" between July 4 and July 29, 2005, at Pt. Reyes, California. Observations from in situ aerosol instruments and from the ARM Mobile Facility will be combined in a first look at observations from this period. The in situ aerosol measurements included high time resolution data of size-resolved bulk composition (sulfate, nitrate, NH4, organics, etc.) and single particle analysis to determine elemental composition and morphology. A CCN counter was also deployed to measure the fraction of cloud droplet kernels that are CCN active over a range of super-saturations. Our presentation will partition measurements into periods of cloudy and cloud-free periods, and will also be partitioned between periods associated with northerly back trajectories that arrived at Pt. Reyes after passing along the Washington-Oregon coast, westerly oceanic trajectories and a very limited number of periods when the air flow appeared to be associated with urban areas to the south and southeast.

  6. Ambient particle characterization by single particle aerosol mass spectrometry in an urban area of Beijing

    NASA Astrophysics Data System (ADS)

    Li, Lei; Li, Mei; Huang, Zhengxu; Gao, Wei; Nian, Huiqing; Fu, Zhong; Gao, Jian; Chai, Fahe; Zhou, Zhen

    2014-09-01

    To investigate the composition and possible sources of aerosol particles in Beijing urban area, a single particle aerosol mass spectrometer (SPAMS) was deployed from April 22 to May 4, 2011. 510,341 particles out of 2,953,200 sized particles were characterized by SPAMS in combination with the ART-2a neural network algorithm. The particles were classified as rich-K (39.79%), carbonaceous species (32.7%), industry metal (19.2%), dust (5.7%), and rich-Na (1.76%). Industrial emissions related particles, rich-Fe, rich-Pb, and K-nitrate, were the major components of aerosol particles during haze periods, which were mainly from the steel plants and metal smelting processes around Beijing. Under stagnant meterological conditions, these regional emissions have a vital effect on haze formation. Organic carbon (OC) particles were attributed to biomass burning. NaK-EC was likely to come from local traffic emissions. Internally mixed organic and elemental carbon (OCEC) was found to be from possible sources of local traffic emission and biomass burning. It was found that coarse dust particles were mainly composed of four different types of dust particles, dust-Si, dust-Ca, dust-Al, and dust-Ti. It is the first time that SPAMS was used to study a dust storm in Beijing. Our results showed that SPAMS could be a powerful tool in the identification and apportionment of aerosol sources in Beijing, providing useful reference information for environmental control and management.

  7. Electronic cigarette aerosol particle size distribution measurements.

    PubMed

    Ingebrethsen, Bradley J; Cole, Stephen K; Alderman, Steven L

    2012-12-01

    The particle size distribution of aerosols produced by electronic cigarettes was measured in an undiluted state by a spectral transmission procedure and after high dilution with an electrical mobility analyzer. The undiluted e-cigarette aerosols were found to have particle diameters of average mass in the 250-450 nm range and particle number concentrations in the 10(9) particles/cm(3) range. These measurements are comparable to those observed for tobacco burning cigarette smoke in prior studies and also measured in the current study with the spectral transmission method and with the electrical mobility procedure. Total particulate mass for the e-cigarettes calculated from the size distribution parameters measured by spectral transmission were in good agreement with replicate determinations of total particulate mass by gravimetric filter collection. In contrast, average particle diameters determined for e-cigarettes by the electrical mobility method are in the 50 nm range and total particulate masses calculated based on the suggested diameters are orders of magnitude smaller than those determined gravimetrically. This latter discrepancy, and the very small particle diameters observed, are believed to result from almost complete e-cigarette aerosol particle evaporation at the dilution levels and conditions of the electrical mobility analysis. A much smaller degree, ~20% by mass, of apparent particle evaporation was observed for tobacco burning cigarette smoke. The spectral transmission method is validated in the current study against measurements on tobacco burning cigarette smoke, which has been well characterized in prior studies, and is supported as yielding an accurate characterization of the e-cigarette aerosol particle size distribution.

  8. 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

  9. 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

  10. Individual-Particle Analysis of Aerosols From Southern Africa

    NASA Astrophysics Data System (ADS)

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

    2001-12-01

    Aerosol samples were collected on the University of Washington Convair-580 research aircraft over southern Africa during the Safari 2000 Experiment. Individual aerosol particles were analyzed using transmission electron microscopy (TEM) and field-emission scanning electron microscopy (FESEM) with energy-dispersive x-ray spectrometry (EDS). The objective of the study is to characterize the major aerosol emissions from biomass burning over southern Africa, with emphasis on the sizes, shapes, compositions, mixing states, and surface coatings of the aerosols. Aging and reaction of smoke aerosols with plume transport were investigated. Particulate emissions from combustion of different vegetation types and at different burning phases were compared. Preliminary results show that aerosols from biomass burning mainly consist of amorphous carbonaceous spherules ("tar balls"); soot; K salts including KCl, K2SO4, and probably KNO3 mixed with organic particles; and Ca-bearing particles including Ca carbonate, phosphate, and sulfate. Minor amounts of sea salt and minerals such as quartz, mica, smectite, and gypsum are also present. The relative concentrations of tar balls increase with distance from the fires. More KCl particles occur in fresh smoke plumes close to fire sources, whereas more K2SO4 and KNO3 particles are present in aged smoke. This change indicates that KCl forming from the fire was converted to K2SO4 and KNO3 through reactions with S- and N-bearing species emitted from biomass burning. The conversion of KCl resembles that of NaCl in sea salt particles, suggesting similar reaction mechanisms with the aging of smoke. More soot is present in smoke from flaming grass fires than bush and wood fires, which is probably related to the high fraction of flaming combustion of grass fires. The high abundance of organic particles and soluble salt may affect the hygroscopic properties of biomass burning aerosols and influence their role as cloud condensation nuclei

  11. 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

  12. Airborne measurements of biomass burning aerosol distribution and composition in the springtime Arctic 2008

    NASA Astrophysics Data System (ADS)

    Thornberry, T.; Froyd, K. D.; Murphy, D. M.; Thomson, D. S.; Brock, C. A.; Cozic, J.; Warneke, C.; Degouw, J.; Middlebrook, A. M.; Bahreini, R.; Brioude, J.

    2008-12-01

    The springtime Arctic troposphere in 2008 was characterized by high concentrations of biomass burning aerosol. During the Aerosol, Radiation, and Cloud Processes affecting Arctic Climate (ARCPAC) campaign, airborne measurements of aerosol composition by the NOAA single particle mass spectrometer instrument (PALMS) identified biomass burning particles using an established composition tracer. Fires in northern Asia produced biomass burning aerosol that were transported to the Arctic within 3-12 days. Concentrations of biomass burning aerosols were elevated not only within well defined plumes, but also regionally throughout the Arctic. Above the boundary layer, biomass burning particles dominated the total aerosol volume and were largely responsible for the Arctic Haze observed during the period of study. The composition of plume aerosols varied according to source region, transport time, and anthropogenic influence.

  13. Aerosol particles and the formation of advection fog

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Liaw, G. S.; Vaughan, O. H., Jr.

    1979-01-01

    A study of numerical simulation of the effects of concentration, particle size, mass of nuclei, and chemical composition on the dynamics of warm fog formation, particularly the formation of advection fog, is presented. This formation is associated with the aerosol particle characteristics, and both macrophysical and microphysical processes are considered. In the macrophysical model, the evolution of wind components, water vapor content, liquid water content, and potential temperature under the influences of vertical turbulent diffusion, turbulent momentum, and turbulent energy transfers are taken into account. In the microphysical model, the supersaturation effect is incorporated with the surface tension and hygroscopic material solution. It is shown that the aerosol particles with the higher number density, larger size nuclei, the heavier nuclei mass, and the higher ratio of the Van't Hoff factor to the molecular weight favor the formation of the lower visibility advection fogs with stronger vertical energy transfer during the nucleation and condensation time period.

  14. Subarctic atmospheric aerosol composition: 2. Hygroscopic growth properties

    SciTech Connect

    Herich, Hanna; Kammermann, Lukas; Friedman, Beth; Gross, Deborah S.; Weingartner, E.; Lohmann, U.; Spichtinger, Peter; Gysel, Martin; Baltensperger, Urs; Cziczo, Daniel J.

    2009-07-10

    Sub-arctic aerosols were sampled during July 2007 at the Abisko Scientific Research Station Stordalen site in northern Sweden with an instrument setup consisting of a custom-built Hygroscopicity Tandem Differential Mobility Analyzer (HTDMA) connected in series to a single particle mass spectrometer. Aerosol chemical composition in the form of bipolar single particle mass spectra was determined as a function of hygroscopic growth both in situ and in real time. The HTDMA was deployed at a relative humidity of 82% and particles with a dry mobility diameter of 260 nm were selected. Aerosols from two distinct airmasses were analyzed during the sampling period. Sea salt aerosols were found to be the dominant particle group with the highest hygroscopicity. High intensities of sodium and related peaks in the mass spectra were identified as exclusive markers for large hygroscopic growth. Particles from biomass combustion were found to be the least hygroscopic aerosol category. Species normally considered soluble (e.g., sulfates and nitrates) were found in particles ranging from high to low hygroscopicity. Furthermore, the signal intensities of the peaks related to these species did not correlate with hygroscopicity.

  15. 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

  16. Surface Chemistry at Size-Selected Nano-Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Roberts, Jeffrey

    2005-03-01

    A method has been developed to conduct surface chemistry and extract surface kinetic rates from size-selected aerosol nanoparticles. The measurements encompass broad ranges of particle size, phase, and composition. Results will be presented on the uptake of water by aerosolized soot nanoparticles of radius between 10 and 40 nm. Water uptake was monitored by tandem differential mobility analysis (T-DMA), which is capable of measuring changes in particle diameter as little as 0.2 nm. Soot particles were produced in an ethene diffusion flame and extracted into an atmospheric pressure aerosol flow tube reactor. The particles were subjected to various thermal and oxidative treatments, and the effects of these treatments on the ability of soot to adsorb monolayer quantities of water was determined. The results are important because soot nucleates atmospheric cloud particles. More generally, the results represent one of the first kinetic and mechanistic studies of gas-phase nanoparticle reactivity. Co-author: Henry Ajo, University of Minnesota

  17. 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.

  18. Size-Segregated Aerosol Composition and Mass Loading of Atmospheric Particles as Part of the Pacific Northwest 2001(PNW2001) Air Quality Study In Puget Sound

    NASA Astrophysics Data System (ADS)

    Disselkamp, R. S.; Barrie, L. A.; Shutthanadan, S.; Cliff, S.; Cahill, T.

    2001-12-01

    In mid-August, 2001, an aircraft-based air-quality study was performed in the Puget Sound, WA, area entitled PNW2001 (http://www.pnl.gov/pnw2001). The objectives of this field campaign were the following: 1. reveal information about the 3-dimensional distribution of ozone, its gaseous precursors and fine particulate matter during weather conditions favoring air pollution; 2. derive information about the accuracy of urban and biogenic emissions inventories that are used to drive the air quality forecast models; and 3. examine the accuracy of modeled ozone concentration with that observed. In support of these efforts, we collected time-averaged ( { ~}10 minute averages), size-segregated, aerosol composition and mass-loading information using ex post facto analysis techniques of synchrotron x-ray fluorescence (s-XRF), proton induced x-ray emissions(PIXE), proton elastic scattering (PESA), and scanning transmission ion microscopy (STIM). This is the first time these analysis techniques have been used together on samples collected from aircraft using an optimized 3-stage rotating drum impactor. In our presentation, we will discuss the aerosol components in three aerosol size fractions as identified by statistical analysis of multielemental data (including total mass, H, Na, Mg, Al, Si, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Pb) and relate variations in these components to physical aerosol properties, other gaseous trace constituents and to air mass origin.

  19. Differentiation of hydrophobic from hydrophilic submicrometer aerosol particles

    SciTech Connect

    Juozaitis, A.; Ulevicius, V.; Girgzdys, A. ); Willeke, K. )

    1993-02-01

    A method has been developed that differentiates hydrophobic from hydrophilic submicrometer aerosol particles in air environments containing polydisperse aerosols composed of different chemical species. First, a narrow particle size range is extracted from the polydisperse aerosol by an electrostatic aerosol classifier. Then the monodisperse aerosols of different origins are exposed to preselected supersaturation levels and are size-classified again by a second electrostatic classifier. Hydrophobic aerosol particles pass through the second classifier when its size window matches that of the first classifier. Hydrophilic aerosol particles grow to a larger size and are removed by the second classifier. The method has been applied in the field by measuring the fraction of hydrophobic atmospheric particles in a suburb of Vilnius, Lithuania, during a period of high emission of hydrophobic soot particles from residential coal and industrial oil burning in winter. 33 refs., 4 figs.

  20. Characterization of aerosols and fibers emitted from composite materials combustion.

    PubMed

    Chivas-Joly, C; Gaie-Levrel, F; Motzkus, C; Ducourtieux, S; Delvallée, A; De Lagos, F; Nevé, S Le; Gutierrez, J; Lopez-Cuesta, J-M

    2016-01-15

    This work investigates the aerosols emitted during combustion of aircraft and naval structural composite materials (epoxy resin/carbon fibers and vinyl ester/glass fibers and carbon nanotubes). Combustion tests were performed at lab-scale using a modified cone calorimeter. The aerosols emitted have been characterized using various metrological devices devoted to the analysis of aerosols. The influence of the nature of polymer matrices, the incorporation of fibers and carbon nanotubes as well as glass reinforcements on the number concentration and the size distribution of airborne particles produced, was studied in the 5 nm-10 μm range. Incorporation of carbon fibers into epoxy resin significantly reduced the total particle number concentration. In addition, the interlaced orientation of carbon fibers limited the particles production compared to the composites with unidirectional one. The carbon nanotubes loading in vinyl ester resin composites influenced the total particles production during the flaming combustion with changes during kinetics emission. Predominant populations of airborne particles generated during combustion of all tested composites were characterized by a PN50 following by PN(100-500).

  1. Spatial Variability of CCN Sized Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Asmi, A.; Väänänen, R.

    2014-12-01

    The computational limitations restrict the grid size used in GCM models, and for many cloud types they are too large when compared to the scale of the cloud formation processes. Several parameterizations for e.g. convective cloud formation exist, but information on spatial subgrid variation of the cloud condensation nuclei (CCNs) sized aerosol concentration is not known. We quantify this variation as a function of the spatial scale by using datasets from airborne aerosol measurement campaigns around the world including EUCAARI LONGREX, ATAR, INCA, INDOEX, CLAIRE, PEGASOS and several regional airborne campaigns in Finland. The typical shapes of the distributions are analyzed. When possible, we use information obtained by CCN counters. In some other cases, we use particle size distribution measured by for example SMPS to get approximated CCN concentration. Other instruments used include optical particle counters or condensational particle counters. When using the GCM models, the CCN concentration used for each the grid-box is often considered to be either flat, or as an arithmetic mean of the concentration inside the grid-box. However, the aircraft data shows that the concentration values are often lognormal distributed. This, combined with the subgrid variations in the land use and atmospheric properties, might cause that the aerosol-cloud interactions calculated by using mean values to vary significantly from the true effects both temporary and spatially. This, in turn, can cause non-linear bias into the GCMs. We calculate the CCN aerosol concentration distribution as a function of different spatial scales. The measurements allow us to study the variation of these distributions within from hundreds of meters up to hundreds of kilometers. This is used to quantify the potential error when mean values are used in GCMs.

  2. 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

  3. Laboratory and Ambient Studies Using an Automated Semi-Continuous Single-Particle Aerosol Raman Spectrometer

    NASA Astrophysics Data System (ADS)

    Doughty, D., III; Hill, S. C.

    2015-12-01

    Single-particle Raman spectra can yield extensive information about in-situ ambient particulate composition. However, Raman spectral measurements of individual aerosol particles typically require collection of samples in the field followed by offline Raman spectral measurements in a laboratory. The process requires considerable operator time. We report results obtained with an automated, single-particle Aerosol Raman Spectrometer built by Battelle, which is the core of Battelle's Resource Effective Bioidentification System (REBS). This instrument collects aerosol particles onto a metallized polymer tape and simultaneously measures Raman spectra of particles obtained during the previous collection period. At the end of each collection period (typically 15 minutes), the tape is advanced and the next collection and measurement period is begun. In this way, particles are semi-continuously sampled and their Raman spectra are measured. We show laboratory data from different sizes of polystyrene latex spheres. We also show results from calcium sulfate particles, vehicular emission soot, and other particles. We discuss the influence of imaging time on the quality of the Raman spectra measured and on the ability of the instrument to resolve aerosol particles. Finally, we present results from an outdoor sampling period during the summer of 2015 where the instrument ran unattended for more than one week collecting particles and measuring their Raman spectra. We suggest that the routine use of such an automated particle-sampling instrument should increase our understanding of inorganic and organic aerosols including biological aerosols and sources and fates of these particles.

  4. Continuous measurements of aerosol particles in Arctic Russia and Finland

    NASA Astrophysics Data System (ADS)

    Asmi, Eija; Kondratyev, Vladimir; Brus, David; Lihavainen, Heikki; Laurila, Tuomas; Aurela, Mika; Hatakka, Juha; Viisanen, Yrjö; Reshetnikov, Alexander; Ivakhov, Victor; Uttal, Taneil; Makshtas, Alexander

    2013-04-01

    The Arctic and northern boreal regions of Eurasia are experiencing rapid environmental changes due to pressures by human activities. The largest anthropogenic climate forcings are due to aerosol particles and greenhouse gases (GHGs). The Arctic environment is highly sensitive to changes in aerosol concentrations or composition, largely due to the high surface reflectance for the most part of the year. Concentrations of aerosols in winter and spring Arctic are affected by 'Arctic Haze', a phenomenon suggested to arise from the transport of pollutants from lower latitudes and further strengthened by the strong stratification of the Arctic wintertime atmosphere. Sources and transport patterns of aerosols into the Arctic are, however, not fully understood. In order to monitor the changes within the Arctic region, as well as to understand the sources and feedback mechanisms, direct measurements of aerosols within the Arctic are needed. So far, direct year-round observations have been inadequate especially within the Russian side of the Arctic. This is the reason why a new climate observatory was founded in Tiksi, Russia. Tiksi meteorological observatory in northern Siberia (71o 36' N; 128o 53' E) on the shore of the Laptev Sea has been operating since 1930s. Recently, it was upgraded and joint in the network of the IASOA, in the framework of the International Polar Year Activity project. The project is run in collaboration between National Oceanic and Atmospheric Administration (NOAA) with the support of the National Science Foundation (NSF), Roshydromet (AARI and MGO units), government of the Republic of Sakha (Yakutia) and the Finnish Meteorological Institute (FMI). The research activities of FMI in Tiksi include e.g. continuous long-term measurements of aerosol physical properties, which have been successfully continued since summer 2010. These, together with the FMI measurements in Pallas station in northern Finland since 1999, provide important information on the

  5. Aerosol composition and sources during the Chinese Spring Festival: fireworks, secondary aerosol, and holiday effects

    NASA Astrophysics Data System (ADS)

    Jiang, Q.; Sun, Y. L.; Wang, Z.; Yin, Y.

    2015-06-01

    Aerosol particles were characterized by an Aerodyne aerosol chemical speciation monitor along with various collocated instruments in Beijing, China, to investigate the role of fireworks (FW) and secondary aerosol in particulate pollution during the Chinese Spring Festival of 2013. Three FW events, exerting significant and short-term impacts on fine particles (PM2.5), were observed on the days of Lunar New Year, Lunar Fifth Day, and Lantern Festival. The FW were shown to have a large impact on non-refractory potassium, chloride, sulfate, and organics in submicron aerosol (PM1), of which FW organics appeared to be emitted mainly in secondary, with its mass spectrum resembling that of secondary organic aerosol (SOA). Pollution events (PEs) and clean periods (CPs) alternated routinely throughout the study. Secondary particulate matter (SPM = SOA + sulfate + nitrate + ammonium) dominated the total PM1 mass on average, accounting for 63-82% during nine PEs in this study. The elevated contributions of secondary species during PEs resulted in a higher mass extinction efficiency of PM1 (6.4 m2 g-1) than during CPs (4.4 m2 g-1). The Chinese Spring Festival also provides a unique opportunity to study the impact of reduced anthropogenic emissions on aerosol chemistry in the city. Primary species showed ubiquitous reductions during the holiday period with the largest reduction being in cooking organic aerosol (OA; 69%), in nitrogen monoxide (54%), and in coal combustion OA (28%). Secondary sulfate, however, remained only slightly changed, and the SOA and the total PM2.5 even slightly increased. Our results have significant implications for controlling local primary source emissions during PEs, e.g., cooking and traffic activities. Controlling these factors might have a limited effect on improving air quality in the megacity of Beijing, due to the dominance of SPM from regional transport in aerosol particle composition.

  6. Influence of particle size and chemistry on the cloud nucleating properties of aerosols

    NASA Astrophysics Data System (ADS)

    Quinn, P. K.; Bates, T. S.; Coffman, D. J.; Covert, D. S.

    2008-02-01

    The ability of an aerosol particle to act as a cloud condensation nuclei (CCN) is a function of the size of the particle, its composition and mixing state, and the supersaturation of the cloud. In-situ data from field studies provide a means to assess the relative importance of these parameters. During the 2006 Texas Air Quality - Gulf of Mexico Atmospheric Composition and Climate Study (TexAQS-GoMACCS), the NOAA RV Ronald H. Brown encountered a wide variety of aerosol types ranging from marine near the Florida panhandle to urban and industrial in the Houston-Galveston area. These varied sources provided an opportunity to investigate the role of aerosol sources and chemistry in the potential activation of particles to form cloud droplets. Measurements were made of CCN concentrations, aerosol chemical composition in the size range relevant for particle activation in warm clouds, and aerosol size distributions. Variability in aerosol composition was parameterized by the mass fraction of Hydrocarbon-like Organic Aerosol (HOA) for particle diameters less than 200 nm (vacuum aerodynamic). The HOA mass fraction in this size range was lowest for marine aerosol and highest for aerosol sampled close to anthropogenic sources. Combining all data from the experiment reveals that composition (defined by HOA mass fraction) explains 40% of the variance in the critical diameter for particle activation at the instrumental supersaturation (S) of 0.44%. Correlations between HOA mass fraction and aerosol mean diameter show that these two parameters are essentially independent of one another for this data set. We conclude that, based on the variability of the HOA mass fraction observed during TexAQS-GoMACCS, variability in particle composition played a significant role in determining the fraction of particles that could activate to form cloud droplets. Using a simple model based on Köhler theory and the assumption that HOA is insoluble, we estimate the degree to which calculated CCN

  7. 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

  8. 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

  9. 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

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

    NASA Astrophysics Data System (ADS)

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

    1994-05-01

    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°, 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 size distribution, based on the spectral dependence of the optical thickness, a, cannot estimate accurately the phase function (up to 50% error for λ = 0.87 μm). Before the Pinatubo eruption the ratio between the volumes of sulfate and coarse particles was very well correlated with α. 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 distributions before the injection of stratospheric aerosol consistently show two modes, sulfate particles with rm

  11. Aerosol composition and sources during the Chinese Spring Festival: fireworks, secondary aerosol, and holiday effects

    NASA Astrophysics Data System (ADS)

    Jiang, Q.; Sun, Y. L.; Wang, Z.; Yin, Y.

    2014-08-01

    Aerosol particles were characterized by an Aerodyne Aerosol Chemical Speciation Monitor (ACSM) along with various collocated instruments in Beijing, China to investigate the aerosol composition and sources during the Chinese Spring Festival, 2013. Three fireworks (FW) events exerting significant and short-term impacts on fine particles (PM2.5) were observed on the days of Lunar New Year, Lunar Fifth Day, and Lantern Festival. The FW showed major impacts on non-refractory potassium, chloride, sulfate, and organics in PM1, of which the FW organics appeared to be mainly secondary with its mass spectrum resembling to that of secondary organic aerosol (SOA). Pollution events (PEs) and clean periods (CPs) alternated routinely throughout the study. Secondary particulate matter (SPM = SOA + sulfate + nitrate + ammonium) dominated PM1 accounting for 63-82% during the nine PEs observed. The elevated contributions of secondary species during PEs resulted in a higher mass extinction efficiency of PM1 (6.4 m2 g-1) than that during CPs (4.4 m2 g-1). The Chinese Spring Festival also provides a unique opportunity to study the impacts of reduced anthropogenic emissions on aerosol chemistry in the city. The primary species showed ubiquitous reductions during the holiday period with the largest reduction for cooking OA (69%), nitrogen monoxide (54%), and coal combustion OA (28%). The secondary sulfate, however, remained minor change, and the SOA and the total PM2.5 even slightly increased. These results have significant implications that controlling local primary source emissions, e.g., cooking and traffic activities, might have limited effects on improving air quality during PEs when SPM that is formed over regional scales dominates aerosol particle composition.

  12. 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

  13. 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.; ...

    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

  14. Combined effects of organic aerosol loading and fog processing on organic aerosols oxidation, composition, and evolution.

    PubMed

    Chakraborty, Abhishek; Gupta, Tarun; Tripathi, S N

    2016-12-15

    Chemical characterization of ambient non-refractory submicron aerosols (NR-PM1) was carried out in real time at Kanpur, India. The measurements were performed during the winter (December 2014 to February 2015), and comprised of two very distinct high and low aerosol loading periods coupled with prevalent foggy conditions. The average non-refractory submicron aerosol loading varied significantly from high (HL, ~240μg/m(3)) to low loading (LL, ~100μg/m(3)) period and was dominated by organic aerosols (OA) which contributed more than half (~60%) of the measured aerosol mass. OA source apportionment via positive matrix factorization (PMF) showed drastic changes in the composition of OA from HL to LL period. Overall, O/C (oxygen to carbon) ratios also varied significantly from HL (=0.59) to LL (=0.69) period. Fog episodes (n=17) studied here seem to be reducing the magnitude of the negative impact of OA loading on O/C ratio (OA loading and O/C ratio are anti-correlated, as higher OA loading allows gas to particle partitioning of relatively less oxidized organics) by 60% via aqueous processing. This study provided new insights into the combined effects of OA loading and fog aqueous processing on the evolution of ambient organic aerosols (OA) for the first time.

  15. 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

  16. Moving particle composition analyzer

    NASA Technical Reports Server (NTRS)

    Auer, S. O. (Inventor)

    1976-01-01

    A mass spectrometry apparatus for analyzing the composition of moving microscopic particles is introduced. The apparatus includes a capacitor with a front electrode upon which the particles impinge, a back electrode, and a solid dielectric sandwiched between the front and back electrodes. In one embodiment, the electrodes and dielectric are arcuately shaped as concentric peripheral segments of different spheres having a common center and different radii. The front electrode and dielectric together have a thickness such that an impinging particle can penetrate them. In a second embodiment, the capacitor has planar, parallel electrodes, in which case the ejected positive ions are deflected downstream of a planar grid by a pair of spaced, arcuate capacitor plates having a region between them through which the ejected ions travel.

  17. Single particle characterization using a light scattering module coupled to a time-of-flight aerosol mass spectrometer

    SciTech Connect

    Cross, E.; Onasch, Timothy B.; Canagaratna, Manjula; Jayne, J. T.; Kimmel, Joel; Yu, Xiao-Ying; Alexander, M. L.; Worsnop, Douglas R.; Davidovits, Paul

    2009-10-01

    To accurately model the radiative forcing of aerosol particles, one must measure in real-time the size, shape, density, chemical composition, and mixing state of ambient particles. This is a formidable challenge because the chemical and physical properties of the aerosol particles are highly complex, dependent on the emission sources, the geography and meteorology of the surroundings, and the gas phase composition of the regional atmosphere.

  18. Initial size distributions and hygroscopicity of indoor combustion aerosol particles

    SciTech Connect

    Li, W.; Hopke, P.K.

    1993-10-01

    Cigarette smoke, incense smoke, natural gas flames, propane fuel flames, and candle flames are contributors of indoor aerosol particles. To provide a quantitative basis for the modeling of inhaled aerosol deposition pattern, the hygroscopic growth of particles from these five sources as well as the source size distributions were measured. Because the experiments were performed on the bases of particles of single size, it provided not only the averaged particle`s hygroscopic growth of each source, but also the detailed size change for particles of different sizes within the whole size spectrum. The source particle size distribution measurements found that cigarette smoke and incense smoke contained particles in the size range of 100-700 nm, while the natural gas, propane, and candle flames generated particles between 10 and 100 nm. The hygroscopic growth experiments showed that these combustion aerosol particles could grow 10% to 120%, depending on the particle sizes and origins. 18 refs., 15 figs., 3 tabs.

  19. Direct aerosol chemical composition measurements to evaluate the physicochemical differences between controlled sea spray aerosol generation schemes

    NASA Astrophysics Data System (ADS)

    Collins, D. B.; Zhao, D. F.; Ruppel, M. J.; Laskina, O.; Grandquist, J. R.; Modini, R. L.; Stokes, M. D.; Russell, L. M.; Bertram, T. H.; Grassian, V. H.; Deane, G. B.; Prather, K. A.

    2014-11-01

    Controlled laboratory studies of the physical and chemical properties of sea spray aerosol (SSA) must be under-pinned by a physically and chemically accurate representation of the bubble-mediated production of nascent SSA particles. Bubble bursting is sensitive to the physico-chemical properties of seawater. For a sample of seawater, any important differences in the SSA production mechanism are projected into the composition of the aerosol particles produced. Using direct chemical measurements of SSA at the single-particle level, this study presents an intercomparison of three laboratory-based, bubble-mediated SSA production schemes: gas forced through submerged sintered glass filters ("frits"), a pulsed plunging-waterfall apparatus, and breaking waves in a wave channel filled with natural seawater. The size-resolved chemical composition of SSA particles produced by breaking waves is more similar to particles produced by the plunging waterfall than those produced by sintered glass filters. Aerosol generated by disintegrating foam produced by sintered glass filters contained a larger fraction of organic-enriched particles and a different size-resolved elemental composition, especially in the 0.8-2 μm dry diameter range. Interestingly, chemical differences between the methods only emerged when the particles were chemically analyzed at the single-particle level as a function of size; averaging the elemental composition of all particles across all sizes masked the differences between the SSA samples. When dried, SSA generated by the sintered glass filters had the highest fraction of particles with spherical morphology compared to the more cubic structure expected for pure NaCl particles produced when the particle contains relatively little organic carbon. In addition to an intercomparison of three SSA production methods, the role of the episodic or "pulsed" nature of the waterfall method on SSA composition was under-taken. In organic-enriched seawater, the continuous

  20. Retrieval of aerosol composition using ground-based remote sensing measurements

    NASA Astrophysics Data System (ADS)

    Xie, Yisong; Li, Zhengqiang; Zhang, Ying; Li, Donghui; Li, Kaitao

    2016-04-01

    states of aerosol particles on aerosol composition retrieval.

  1. Retrieval of aerosol composition using ground-based remote sensing measurements

    NASA Astrophysics Data System (ADS)

    Xie, Y.; Li, Z.; Xu, H.; Chen, X.; Li, K.; Lv, Y.; Li, D.; Zhang, Y.

    2015-12-01

    The chemical composition and mixing status of ambient aerosol are the main factors deciding aerosol microphysical and optical properties, and thus have significant impacts on regional or global climate change and air quality. Traditional approaches to detect atmospheric aerosol composition include sampling with laboratory analysis and in-situ measurement. They can accurately acquire aerosol components, however, the sampling or air exhausting could change the status of aerosol or have some mass loss. Additionally, aerosol is usually sampled at the surface level so that it is difficult to detect the columnar aerosol properties. Remote sensing technology, however, can overcome these problems because it investigate aerosol information by optical and microphysical properties without destructing the natural status of ambient aerosol. This paper introduce a method to acquire aerosol composition by the remote sensing measurements of CIMEL CE318 ground-based sun-sky radiometer. A six component aerosol model is used in this study, including one strong absorbing component Black Carbon (BC), two partly absorbing components Brown Carbon (BrC) and Mineral Dust (MD), two scattering components Ammonia Sulfate-like (AS) and Sea Salt (SS), and Aerosol Water uptake (AW). Sensitivity analysis are performed to find the most sensitive parameters to each component and retrieval method for each component is accordingly developed. The residual minimization method is used by comparing remote sensing measurements and simulation outputs to find the optimization of aerosol composition (including volume fraction and mass concentration of each component). This method is applied to real measurements obtained from Beijing site under different weather conditions, including polluted haze, dust storm and clean days, to investigate the impacts of mixing states of aerosol particles on aerosol composition retrieval.

  2. Size-resolved aerosol composition and its link to hygroscopicity at a forested site in Colorado

    NASA Astrophysics Data System (ADS)

    Levin, E. J. T.; Prenni, A. J.; Palm, B. B.; Day, D. A.; Campuzano-Jost, P.; Winkler, P. M.; Kreidenweis, S. M.; DeMott, P. J.; Jimenez, J. L.; Smith, J. N.

    2014-03-01

    Aerosol hygroscopicity describes the ability of a particle to take up water and form a cloud droplet. Modeling studies have shown sensitivity of precipitation-producing cloud systems to the availability of aerosol particles capable of serving as cloud condensation nuclei (CCN), and hygroscopicity is a key parameter controlling the number of available CCN. Continental aerosol is typically assumed to have a representative hygroscopicity parameter, κ, of 0.3; however, in remote locations this value can be lower due to relatively large mass fractions of organic components. To further our understanding of aerosol properties in remote areas, we measured size-resolved aerosol chemical composition and hygroscopicity in a forested, mountainous site in Colorado during the six-week BEACHON-RoMBAS (Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics and Nitrogen-Rocky Mountain Biogenic Aerosol Study) campaign. This campaign followed a year-long measurement period at this site, and results from the intensive campaign shed light on the previously reported seasonal cycle in aerosol hygroscopicity. New particle formation events were observed routinely at this site and nucleation mode composition measurements indicated that the newly formed particles were predominantly organic. These events likely contribute to the dominance of organic species at smaller sizes, where aerosol organic mass fractions were between 70 and 90%. Corresponding aerosol hygroscopicity was observed to be in the range κ = 0.15-0.22, with hygroscopicity increasing with particle size. Aerosol chemical composition measured by an aerosol mass spectrometer and calculated from hygroscopicity measurements agreed very well during the intensive study, with an assumed value of κorg = 0.13 resulting in the best agreement.

  3. 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.

  4. Aerosol measurements at a high-elevation site: composition, size, and cloud condensation nuclei activity

    SciTech Connect

    Friedman, Beth; Zelenyuk, Alla; Beranek, Josef; Kulkarni, Gourihar R.; Pekour, Mikhail S.; Hallar, Anna G.; McCubbin, Ian; Thornton, Joel A.; Cziczo, D. J.

    2013-12-09

    We present measurements of CCN concentrations and associated aerosol composition and size properties at a high-elevation research site in March 2011. CCN closure and aerosol hygroscopicity were assessed using simplified assumptions of bulk aerosol properties as well as a new method utilizing single particle composition and size to assess the importance of particle mixing state in CCN activation. Free troposphere analysis found no significant difference between the CCN activity of free tropospheric aerosol and boundary layer aerosol at this location. Closure results indicate that using only size and number information leads to adequate prediction, in the majority of cases within 50%, of CCN concentrations, while incorporating the hygroscopicity parameters of the individual aerosol components measured by single particle mass spectrometry adds to the agreement, in most cases within 20%, between predicted and measured CCN concentrations. For high-elevation continental sites, with largely aged aerosol and low amounts of local area emissions, a lack of chemical knowledge and hygroscopicity may not hinder models in predicting CCN concentrations. At sites influenced by fresh emissions or more heterogeneous particle types, single particle composition information may be more useful in predicting CCN concentrations and understanding the importance of particle mixing state on CCN activation.

  5. Laser velocimeter seed particle sizing by the whisker particle collector and laser aerosol spectrometer methods

    NASA Astrophysics Data System (ADS)

    Crosswy, F. L.; Kingery, M. K.; Schaefer, H. J.; Pfeifer, H. J.

    1989-07-01

    Two different aerosol particle sizing systems, the Whisker Particle Collector (WPC) and the Laser Aerosol Spectrometer (LAS), were evaluated for sizing aerosol particles in the size range of 0.1 to 3.0 micrometers. The evaluation tests were conducted using an aerosol of alumina (Al2O3) particles, an aerosol commonly used to provide light scattering particles for laser velocimeter measurements in high temperature flows. The LAS and WPC measurements were then compared for samples taken from the alumina particle aerosols. Some difficulty was encountered in directly comparing these measurements. Other operational aspects of the two systems were also compared including on-line/off-line data presentation capabilities, field portability and measurement limitations at the small particle end of the size range of interest.

  6. Microphysical processing of aerosol particles in orographic clouds

    NASA Astrophysics Data System (ADS)

    Pousse-Nottelmann, S.; Zubler, E. M.; Lohmann, U.

    2015-01-01

    An explicit and detailed treatment of cloud-borne particles allowing for the consideration of aerosol cycling in clouds has been implemented in the regional weather forecast and climate model COSMO. The effects of aerosol scavenging, cloud microphysical processing and regeneration upon cloud evaporation on the aerosol population and on subsequent cloud formation are investigated. For this, two-dimensional idealized simulations of moist flow over two bell-shaped mountains were carried out varying the treatment of aerosol scavenging and regeneration processes for a warm-phase and a mixed-phase orographic cloud. The results allowed to identify different aerosol cycling mechanisms. In the simulated non-precipitating warm-phase cloud, aerosol mass is incorporated into cloud droplets by activation scavenging and released back to the atmosphere upon cloud droplet evaporation. In the mixed-phase cloud, a first cycle comprises cloud droplet activation and evaporation via the Wegener-Bergeron-Findeisen process. A second cycle includes below-cloud scavenging by precipitating snow particles and snow sublimation and is connected to the first cycle via the riming process which transfers aerosol mass from cloud droplets to snow flakes. In the simulated mixed-phase cloud, only a negligible part of the total aerosol mass is incorporated into ice crystals. Sedimenting snow flakes reaching the surface remove aerosol mass from the atmosphere. The results show that aerosol processing and regeneration lead to a vertical redistribution of aerosol mass and number. However, the processes not only impact the total aerosol number and mass, but also the shape of the aerosol size distributions by enhancing the internally mixed/soluble accumulation mode and generating coarse mode particles. Concerning subsequent cloud formation at the second mountain, accounting for aerosol processing and regeneration increases the cloud droplet number concentration with possible implications for the ice

  7. Microphysical processing of aerosol particles in orographic clouds

    NASA Astrophysics Data System (ADS)

    Pousse-Nottelmann, S.; Zubler, E. M.; Lohmann, U.

    2015-08-01

    An explicit and detailed treatment of cloud-borne particles allowing for the consideration of aerosol cycling in clouds has been implemented into COSMO-Model, the regional weather forecast and climate model of the Consortium for Small-scale Modeling (COSMO). The effects of aerosol scavenging, cloud microphysical processing and regeneration upon cloud evaporation on the aerosol population and on subsequent cloud formation are investigated. For this, two-dimensional idealized simulations of moist flow over two bell-shaped mountains were carried out varying the treatment of aerosol scavenging and regeneration processes for a warm-phase and a mixed-phase orographic cloud. The results allowed us to identify different aerosol cycling mechanisms. In the simulated non-precipitating warm-phase cloud, aerosol mass is incorporated into cloud droplets by activation scavenging and released back to the atmosphere upon cloud droplet evaporation. In the mixed-phase cloud, a first cycle comprises cloud droplet activation and evaporation via the Wegener-Bergeron-Findeisen (WBF) process. A second cycle includes below-cloud scavenging by precipitating snow particles and snow sublimation and is connected to the first cycle via the riming process which transfers aerosol mass from cloud droplets to snowflakes. In the simulated mixed-phase cloud, only a negligible part of the total aerosol mass is incorporated into ice crystals. Sedimenting snowflakes reaching the surface remove aerosol mass from the atmosphere. The results show that aerosol processing and regeneration lead to a vertical redistribution of aerosol mass and number. Thereby, the processes impact the total aerosol number and mass and additionally alter the shape of the aerosol size distributions by enhancing the internally mixed/soluble Aitken and accumulation mode and generating coarse-mode particles. Concerning subsequent cloud formation at the second mountain, accounting for aerosol processing and regeneration increases

  8. 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

  9. Relationship between aerosol oxidation level and hygroscopic properties of laboratory generated secondary organic aerosol (SOA) particles

    NASA Astrophysics Data System (ADS)

    Massoli, P.; Lambe, A. T.; Ahern, A. T.; Williams, L. R.; Ehn, M.; Mikkilä, J.; Canagaratna, M. R.; Brune, W. H.; Onasch, T. B.; Jayne, J. T.; Petäjä, T.; Kulmala, M.; Laaksonen, A.; Kolb, C. E.; Davidovits, P.; Worsnop, D. R.

    2010-12-01

    Laboratory experiments investigated the relationship between oxidation level and hygroscopic properties of secondary organic aerosol (SOA) particles generated via OH radical oxidation in an aerosol flow reactor. The hygroscopic growth factor at 90% RH (HGF90%), the CCN activity ($\\kappa$ORG,CCN) and the level of oxidation (atomic O:C ratio) of the SOA particles were measured. Both HGF90% and $\\kappa$ORG,CCN increased with O:C; the HGF90% varied linearly with O:C, while $\\kappa$ORG,CCN mostly followed a nonlinear trend. An average HGF90% of 1.25 and $\\kappa$ORG,CCN of 0.19 were measured for O:C of 0.65, in agreement with results reported for ambient data. The $\\kappa$ORG values estimated from the HGF90% ($\\kappa$ORG,HGF) were 20 to 50% lower than paired $\\kappa$ORG,CCN values for all SOA particles except 1,3,5-trimethylbenzene (TMB), the least hygroscopic of the SOA systems. Within the limitations of instrumental capabilities, we show that differences in hygroscopic behavior among the investigated SOA systems may correspond to differences in elemental composition.

  10. 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

  11. Micro-physical properties of carbonaceous aerosol particles generated by laser ablation of a graphite target

    NASA Astrophysics Data System (ADS)

    Ajtai, T.; Utry, N.; Pintér, M.; Tápai, Cs.; Kecskeméti, G.; Smausz, T.; Hopp, B.; Bozóki, Z.; Szabó, G.

    2014-09-01

    In this work the authors propose laser ablation as a highly versatile tool for carbonaceous aerosol generation. The generated carbonaceous particles can be used as a model aerosol for atmospheric black carbon. Various microphysical properties including mass concentration, size distribution and morphology of aerosol particles generated by laser ablation of a high purity graphite sample were investigated in detail. These measurements proved that the proposed method can be used to generate both primary particles and fractal aggregates with a high yield. As a further advantage of the method the size distribution of the generated aerosol can cover a wide range, and can be tuned accurately with laser fluence, the ambient composition or with the volumetric flow rate of the carrier gas.

  12. Composition of the Martian aerosols through near-IR spectroscopy

    NASA Technical Reports Server (NTRS)

    Erard, Stephane; Cerroni, Priscilla; Coradini, Angioletta

    1993-01-01

    Near-infrared spectroscopy is a powerful technique to study the composition of planetary surfaces, as the main minerals exhibit absorption bands in this spectral range. It gave important information on the mineralogy and petrology of Mars in the past twenty years although in this case it is well known that a large fraction of light is scattered by the airborne particles before reaching the surface. The measured signal is thus the sum of two different contributions that should be studied separately: One from the surface and one from the aerosols that depends on their density, size distribution and composition. Data from the ISM imaging spectrometer are used here to derive the aerosols spectrum. They consist in sets of spectra (from 0.76 to 3.16 microns) of approximately 3000 pixels approximately 25x25 sq km in size. The resulting spectrum exhibits both water-ice and clay mineral features superimposed on a scattering continuum.

  13. 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.

  14. 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

    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 particles of the same composition would allow proving that LLPS indeed occurs in particles of accumulation mode size. Up to now LLPS has not been studied for particles in this size range. References: 1. Bertram, et al. Atmos. Chem & Phys, 11(21), 10995-11006, 2011.
 2. Krieger, et al. Chemical Society Reviews, 41(19), 6631-6662, 2012 
3. Song, M. et al. Geophys Res Lett, 39(19), 2012b 4. Smith et al. Atmos Chem & Phys, 12(20), 9613- 9628, 2012.
 5. You, Y. et al. Proceedings of the National Academy of Sciences, 109(33), 13188-13193, 2012.

  15. A conceptual framework for mixing structures in individual aerosol particles

    NASA Astrophysics Data System (ADS)

    Li, Weijun; Sun, Jiaxing; Xu, Liang; Shi, Zongbo; Riemer, Nicole; Sun, Yele; Fu, Pingqing; Zhang, Jianchao; Lin, Yangting; Wang, Xinfeng; Shao, Longyi; Chen, Jianmin; Zhang, Xiaoye; Wang, Zifa; Wang, Wenxing

    2016-11-01

    This study investigated the particle size- and age-dependent mixing structures of individual particles in clean and polluted air. Aerosols were classified into eight components: sea salt, mineral dust, fly ash, metal, soot, sulfates, nitrates, and organic matter (OM). Based on our aerosol classification, a particle that consists of two or more aerosol components can be defined as an internally mixed particle. Otherwise, it is considered to be an externally mixed particle. Within the internally mixed particle class, we identified four heterogeneous mixing structures: core-shell, dumbbell, OM coating, and dispersed OM, as well as one homogeneous-like mixing structure. Homogeneous-like mixing mainly occurred in fine particles (<1 µm), while the frequency of heterogeneously mixed particles increased with particle size. Our study demonstrated that particle mixing structures depend on particle size and location and evolve with time. OM-coating and core-shell structures are important indicators for particle aging in air as long as they are distant from specific emission sources. Long-range transported particles tended to have core-shell and OM-coating structures. We found that secondary aerosol components (e.g., sulfates, nitrates, and organics) determined particle mixing structures, because their phases change following particle hydration and dehydration under different relative humidities. Once externally mixed particles are transformed into internally mixed particles, they cannot revert to their former state, except when semivolatile aerosol components are involved. Categorizing mixing structures of individual particles is essential for studying their optical and hygroscopic properties and for tracing the development of their physical or chemical properties over time.

  16. 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.

  17. 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

  18. Contrasting the Evaporation and Condensation of Water from Glassy and Amorphous Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Reid, J. P.; Bones, D. L.; Power, R.; Lienhard, D.; Krieger, U. K.

    2012-04-01

    The partitioning of water between the condensed and gas phases in atmospheric aerosol is usually assumed to occur instantaneously and to be regulated by solution thermodynamics. However, the persistence of high viscosity, glassy and amorphous aerosol to low relative humidity without crystallisation occurring is now widely recognised, suggesting that the timescale for water transport to or from the particle during condensation or evaporation may be significant. A kinetic limitation on water transport could have important implications for understanding hygroscopic growth measurements made on ambient particles, the ability of particles to act as ice nuclei or cloud condensation nuclei, the kinetics of chemical aging/heterogeneous chemistry, and the rate or condensation/evaporation of semi-volatile organic components. In this study we will report on measurements of the timescale of water transport to and from glassy aerosol and ultra-high viscosity solution droplets using aerosol optical tweezers to investigate the time-response of single particles to changes in relative humidity. As a benchmark system, mixed component aerosol particles containing sucrose and sodium chloride have been used; varying the mole fractions of the two solutes allows a wide range of solution viscosities to be studied. We will show that coarse particles can take many thousands of seconds to equilibrate in size and that the timescale correlates with the estimated bulk viscosity of the particle. We will also confirm that significant inhomogeneities in particle composition can be established during evaporation or condensation. Using the experimental data to benchmark a model for equilibration time, predictions can be made of the timescale for the equilibration of accumulation mode particles during water condensation or evaporation and these predictions will be described and their significance explored. Finally, the coalescence dynamics of highly viscous aerosol particles will be reported

  19. Isotope Analysis of Individual Aerosol Particles - a New Tool for Studying Heterogeneous Processes

    NASA Astrophysics Data System (ADS)

    Winterholler, B.; Hoppe, P.; Huth, J.; Andreae, M. O.; Foley, S.

    2006-12-01

    Sources of atmospheric sulfur and its oxidation pathways are studied by isotope analysis of sulfate particles. conventional gas mass spectrometry averages the isotopic compositions of millions of aerosol grains and, therefore, several different types of sulphur aerosol. The new Cameca NanoSIMS 50 ion microprobe technique permits isotope analyses of individual aerosol particles down to 0.5 μm diameter. Combining the chemical composition and isotopic signature of individual particles enables source apportionment of non-sea-salt (nss) sulfate and elucidating mixing processes between nss sulfate and sea-salt sulfate for each sample. Results from aerosol samples collected in Mace Head (Western Ireland) are presented. These samples represent different airmass types, such as clean marine boundary layer air, moderately polluted air and strongly polluted air transported from the continent. Fresh aerosol preserves the original isotopic signature of sea-salt and nss sulfate in separate particles, the latter being present predominantly in the form of ammonium sulfate. This enables us to identify oxidation of nss sulfate in deliquescent sea salt particles by means of their sulfur isotope ratio. Cloud processing however, leads to a complete homogenization as far as the sulfur isotopic signature is concerned.

  20. 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.

  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. New mass measurement method of aerosol particle using vibrating probe particle controlled by radiation pressure

    NASA Astrophysics Data System (ADS)

    Hariyama, Tatsuo; Takaya, Yasuhiro; Miyoshi, Takashi

    2005-11-01

    Aerosol particles with sub-micro meter size inhaled into respiratory systems cause serious damage to human body. In order to evaluate the health effects of the particles, classification methods of the particles with size and mass are needed. Several measurement methods of the particle size are established. However, conventional mass measurement methods are not enough to measure the particles with sub- pico gram. We propose a new mass measurement method of the aerosol particles based on laser trapping. In this method, an optically trapped silica particle is used as a measuring probe particle. The probe particle is trapped at a beam waist of the focused laser light and is forced to vibrate by deflecting the beam waist using AOD. The vibrating probe particle has a resonance frequency because it is governed by the spring-mass-damper system. When an aerosol particle is attached to the probe particle, the resonance frequency shifts according to the increase of the total mass. The mass of the aerosol particle can be measured from the shift of the resonance frequency. Experimentally, it is confirmed that the probe particle is governed by the spring-mass-damper system and has a resonance frequency. When a silica fine particle of 3pg in mass used as an aerosol particle is attached to the probe particle, the resonance frequency shift occurs as expected in the dynamic system and the fine particle mass can be measured based on the proposed method.

  3. 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.

  4. Mass Spectrometric Analysis of Pristine Aerosol Particles During the wet Season of Amazonia - Detection of Primary Biological Particles?

    NASA Astrophysics Data System (ADS)

    Schneider, J.; Zorn, S. R.; Freutel, F.; Borrmann, S.; Chen, Q.; Farmer, D. K.; Jimenez, J. L.; Flores, M.; Roldin, P.; Artaxo, P.; Martin, S. T.

    2008-12-01

    mass spectra that were obtained during AMAZE. First results indicate that the mass spectra of organic aerosol particle sampled during AMAZE show a size dependence, thereby indicating a size-dependent chemical composition of the aerosol particles. A detailed comparison between the laboratory data and the AMS mass spectra of the fraction of large particles sampled during AMAZE will be presented.

  5. 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.

  6. 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.

  7. Importance of aerosol composition, mixing state, and morphology for heterogeneous ice nucleation: A combined field and laboratory approach

    NASA Astrophysics Data System (ADS)

    Baustian, Kelly J.; Cziczo, Daniel J.; Wise, Matthew E.; Pratt, Kerri A.; Kulkarni, Gourihar; Hallar, A. Gannet; Tolbert, Margaret A.

    2012-03-01

    In this study chemical compositions of background aerosol and ice nuclei were examined through laboratory investigations using Raman spectroscopy and field measurements by single-particle mass spectrometry. Aerosol sampling took place at Storm Peak Laboratory in Steamboat Springs, Colorado (elevation of 3210 m). A cascade impactor was used to collect coarse-mode aerosol particles for laboratory analysis by Raman spectroscopy; the composition, mixing state, and heterogeneous ice nucleation activity of individual particles were examined. For in situ analysis of fine-mode aerosol, ice nucleation on ambient particles was observed using a compact ice nucleation chamber. Ice crystals were separated from unactivated aerosol using a pumped counterflow virtual impactor, and ice nuclei were analyzed using particle analysis by laser mass spectrometry. For both fine and coarse modes, the ice nucleating particle fractions were enriched in minerals and depleted in sulfates and nitrates, compared to the background aerosol sampled. The vast majority of particles in both the ambient and ice active aerosol fractions contained a detectable amount of organic material. Raman spectroscopy showed that organic material is sometimes present in the form of a coating on the surface of inorganic particles. We find that some organic-containing particles serve as efficient ice nuclei while others do not. For coarse-mode aerosol, organic particles were only observed to initiate ice formation when oxygen signatures were also present in their spectra.

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

    PubMed

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

    2016-02-02

    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.

  9. REAL-TIME MEASUREMENTS OF THE CHEMICAL COMPOSITION OF SIZE-RESOLVED PARTICLES DURING A SANTA ANA WIND EPISODE, CALIFORNIA USA. (R826240)

    EPA Science Inventory

    Size-resolved particle composition, mass and number concentrations, aerosol scattering coefficients, and prevailing meteorological conditions were measured at the Ellen Browning Scripps Memorial Pier located in La Jolla, California on 15 December 1998. Aerosol particles were s...

  10. Identification of aerosol composition from multi-wavelength lidar measurements

    NASA Technical Reports Server (NTRS)

    Wood, S. A.

    1984-01-01

    This paper seeks to develop the potential of lidar for the identification of the chemical composition of atmospheric aerosols. Available numerical computations suggest that aerosols can be identified by the wavelength dependence of aerosol optical properties. Since lidar can derive the volume backscatter coefficient as a function of wavelength, a multi-wavelength lidar system may be able to provide valuable information on the composition of aerosols. This research theoretically investigates the volume backscatter coefficients for the aerosol classes, sea-salts, and sulfates, as a function of wavelength. The results show that these aerosol compositions can be characterized and identified by their backscatter wavelength dependence. A method to utilize multi-wavelength lidar measurements to discriminate between compositionally different thin aerosol layers is discussed.

  11. 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

  12. Measurement of mass distribution of chemical species in aerosol particles

    NASA Technical Reports Server (NTRS)

    Sinha, M. P.; Friedlander, S. K.

    1984-01-01

    Aerosols may be generated through the nebulizing of solutions and the evaporation of their solvent, leaving the dry solute particles. Attention is presently given to a method for the direct determination of the masses of chemical species in individual aerosol particles on a continuous, real-time basis, using mass spectrometry. After the aerosol particles are introduced into the ion source of a quadrupole mass spectrometer, the particles impinge on a hot rhenium filament in the mass spectrometer's ion source. The resulting vapor plume is ionized by electron bombardment, and a pulse of ions is generated by each particle. The intensities of different masses in the ion pulses can then be measured by the mass spectrometer.

  13. The importance of aerosol composition and mixing state on predicted CCN concentration and the variation of the importance with atmospheric processing of aerosol

    SciTech Connect

    Wang, J.; Cubison, M.; Aiken, A.; Jimenez, J.; Collins, D.; Gaffney, J.; Marley, N.

    2010-03-15

    -independent particle composition leads to substantial overestimation of CCN concentration for freshly emitted aerosols in early morning, but can reasonably predict the CCN concentration after the aerosols underwent atmospheric processing for several hours. This analysis employing various simplifications provides insights into the essential information of particle chemical composition that needs to be represented in models to adequately predict CCN concentration and cloud microphysics.

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

    SciTech Connect

    Hallock, K.A.; Mazurek, M.A. ); Cass, G.R. . Dept. of Environmental Engineering Science)

    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.

  15. Photocatalytic/Magnetic Composite Particles

    NASA Technical Reports Server (NTRS)

    Wu, Chang-Yu; Goswami, Yogi; Garretson, Charles; Andino, Jean; Mazyck, David

    2007-01-01

    Photocatalytic/magnetic composite particles have been invented as improved means of exploiting established methods of photocatalysis for removal of chemical and biological pollutants from air and water. The photocatalytic components of the composite particles are formulated for high levels of photocatalytic activity, while the magnetic components make it possible to control the movements of the particles through the application of magnetic fields. The combination of photocatalytic and magnetic properties can be exploited in designing improved air- and water treatment reactors.

  16. 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.

  17. 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

  18. New apparatus of single particle trap system for aerosol visualization

    NASA Astrophysics Data System (ADS)

    Higashi, Hidenori; Fujioka, Tomomi; Endo, Tetsuo; Kitayama, Chiho; Seto, Takafumi; Otani, Yoshio

    2014-08-01

    Control of transport and deposition of charged aerosol particles is important in various manufacturing processes. Aerosol visualization is an effective method to directly observe light scattering signal from laser-irradiated single aerosol particle trapped in a visualization cell. New single particle trap system triggered by light scattering pulse signal was developed in this study. The performance of the device was evaluated experimentally. Experimental setup consisted of an aerosol generator, a differential mobility analyzer (DMA), an optical particle counter (OPC) and the single particle trap system. Polystylene latex standard (PSL) particles (0.5, 1.0 and 2.0 μm) were generated and classified according to the charge by the DMA. Singly charged 0.5 and 1.0 μm particles and doubly charged 2.0 μm particles were used as test particles. The single particle trap system was composed of a light scattering signal detector and a visualization cell. When the particle passed through the detector, trigger signal with a given delay time sent to the solenoid valves upstream and downstream of the visualization cell for trapping the particle in the visualization cell. The motion of particle in the visualization cell was monitored by CCD camera and the gravitational settling velocity and the electrostatic migration velocity were measured from the video image. The aerodynamic diameter obtained from the settling velocity was in good agreement with Stokes diameter calculated from the electrostatic migration velocity for individual particles. It was also found that the aerodynamic diameter obtained from the settling velocity was a one-to-one function of the scattered light intensity of individual particles. The applicability of this system will be discussed.

  19. Comparing Organic Aerosol Composition from Marine Biogenic Sources to Seawater and to Physical Sea Spray Models

    NASA Astrophysics Data System (ADS)

    Russell, L. M.; Frossard, A. A.; Sanchez, K.; Massoli, P.; Elliott, S.; Burrows, S. M.; Bates, T. S.; Quinn, P.

    2015-12-01

    In much of the marine atmosphere, organic components in aerosol particles have many sources other than sea spray that contribute organic constituents. For this reason, physical sea spray models provide an important technique for studying the organic composition of particles from marine biogenic sources. The organic composition of particles produced by two different physical sea spray models were measured in three open ocean seawater types: (i) Coastal California in the northeastern Pacific, which is influenced by wind-driven, large-scale upwelling leading to productive or eutrophic (nutrient-rich) seawater and high chl-a concentrations, (ii) George's Bank in the northwestern Atlantic, which is also influenced by nutrient upwelling and eutrophic seawater with phytoplankton productivity and high chl-a concentrations, and (iii) the Sargasso Sea in the subtropical western Atlantic, which is oligotrophic and nutrient-limited, reflected in low phytoplankton productivity and low chl-a concentrations. Fourier transform infrared spectroscopy provides information about the functional group composition that represents the marine organic fraction more completely than is possible with techniques that measure non-refractory mass (vaporizable at 650°C). After separating biogenic marine particles from those from other sources, the measured compositions of atmospheric marine aerosol particles from three ocean regions is 65±12% hydroxyl, 21±9% alkane, 6±6% amine, and 7±8% carboxylic acid functional groups. The organic composition of atmospheric primary marine (ocean-derived) aerosol particles is nearly identical to model generated primary marine aerosol particles from bubbled seawater. Variability in productive and non-productive seawater may be caused by the presence of surfactants that can stabilize the bubble film and lead to preferential drainage of the more soluble (lower alkane group fraction) organic components without substantial changes in overall group composition

  20. 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...

  1. 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

  2. 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

  3. Aerosol particle microphotography and glare-spot absorption spectroscopy.

    PubMed

    Arnold, S; Holler, S; Li, J H; Serpengüzel, A; Auffermann, W F; Hill, S C

    1995-04-01

    The relative intensities of glare spots in the image of an electrodynamically trapped aerosol droplet are measured experimentally with an aerosol particle microscope and calculated theoretically. The theoretical calculations are in good agreement with these experiments and indicate that the intensities of these spots are extremely sensitive to the imaginary part of the refractive index. Experimentally, we obtain the molecular absorption spectrum of an impurity within a droplet by recording the spectrum of an individual glare spot produced by broadband illumination.

  4. 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.

  5. Semi-Continuous Measurements of Aerosol Chemical Composition During the Summer 2002 Yosemite National Park Special Study

    SciTech Connect

    Collette, J; Lee, T; Heath, J; Carrico, C; Herckes, P; Engling, G; McMeeking, G; Kreidenweis, S; Day, D; Malm, W; Cahill, T

    2003-02-16

    Semi-continuous measurements of fine particle composition were made over a period of several weeks in summer 2002 in Yosemite National Park, California. These included measurement of aerosol ionic composition (by PILS- Particle-Into-Liquid System) and aerosol carbon (by dual wavelength aethalometer and an R&P particulate carbon monitor). The data reveal that aerosol composition at the site is highly :variable in time, with a strong diurnal cycle. Interestingly, however, different diurnal cycles were sometimes observed for different chemical constituents of the particles. Organic carbon was observed to dominate fine particle mass, with some periods apparently associated with influx of smoke from wildfires in the western U.S. Measurements of fine particle carbon isotopes revealed the fraction of carbon from biogenic sources to range from approximately 73 to 95%. The ionic fraction of the aerosol was usually dominated by ammoniated sulfate. During most periods, PM{sub 2.5} nitrate was found primarily in sea salt particles from which chloride had been displaced. Strong variations in the extent of ammonia neutralization of sulfate were also observed. The ability to observe rapid changes in aerosol composition using these semi-continuous aerosol composition measurements is helpful for understanding the dynamic chemical composition of fine particles responsible for regional haze.

  6. Molecular Characterization of Brown Carbon in Biomass Burning Aerosol Particles

    SciTech Connect

    Lin, Peng; Aiona, Paige K.; Li, Ying; Shiraiwa, Manabu; Laskin, Julia; Nizkorodov, Sergey A.; Laskin, Alexander

    2016-11-01

    Emissions from biomass burning are a significant source of brown carbon (BrC) in the atmosphere. In this study, we investigate the molecular composition of freshly-emitted biomass burning organic aerosol (BBOA) samples collected during test burns of selected biomass fuels: sawgrass, peat, ponderosa pine, and black spruce. We characterize individual BrC chromophores present in these samples using high performance liquid chromatography coupled to a photodiode array detector and a high-resolution mass spectrometer. We demonstrate that both the overall BrC absorption and the chemical composition of light-absorbing compounds depend significantly on the type of biomass fuels and burning conditions. Common BrC chromophores in the selected BBOA samples include nitro-aromatics, polycyclic aromatic hydrocarbon derivatives, and polyphenols spanning a wide range of molecular weights, structures, and light absorption properties. A number of biofuel-specific BrC chromophores are observed, indicating that some of them may be used as potential markers of BrC originating from different biomass burning sources. On average, ~50% of the light absorption above 300 nm can be attributed to a limited number of strong BrC chromophores, which may serve as representative light-absorbing species for studying atmospheric processing of BrC aerosol. The absorption coefficients of BBOA are affected by solar photolysis. Specifically, under typical atmospheric conditions, the 300 nm absorbance decays with a half-life of 16 hours. A “molecular corridors” analysis of the BBOA volatility distribution suggests that many BrC compounds in the fresh BBOA have low volatility (<1 g m-1) and will be retained in the particle phase under atmospherically relevant conditions.

  7. 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

  8. 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.

  9. Ozone, Iodine, and MSA - Case studies in Antarctic aerosol composition from the 2ODIAC Campaign

    NASA Astrophysics Data System (ADS)

    Giordano, M.; Kalnajs, L.; Deshler, T.; Davis, S. M.; Johnson, A.; Slater, A. G.; Goetz, J. D.; Mukherjee, A. D.; DeCarlo, P. F.

    2015-12-01

    Aerosol generation and transport over the Polar Regions, and especially Antarctica, remains a source of uncertainty for geophysical scientists. A characterization of aerosol sources, production, and lifecycle processes in the Polar Regions is required to better understand the polar atmosphere. In an attempt to better characterize Antarctic aerosol and trace gas interactions, the Two-Season, Ozone Depletion and Interaction with Aerosols Campaign (2ODIAC) was launched over the Austral Spring/Summer of 2014 and Austral Winter of 2015. One highlight of the campaign is the first ever deployment of a high-resolution aerosol mass spectrometer to Antarctica. In conjunction with trace gas, meteorology, and aerosol sizing measurements, this presentation will focus on case studies from the campaign relevant to the atmospheric science community. Questions about the role of iodine, MSA, and ozone depletion events in regards to aerosol composition will be examined. Specific attention will be paid to aerosol compositional changes before, during, and after particle bursts especially where changes in aerosol sulfate oxidation occurred (SO2 -> SO4)

  10. Impacts of new particle formation on aerosol cloud condensation nuclei (CCN) activity in Shanghai: case study

    NASA Astrophysics Data System (ADS)

    Leng, C.; Zhang, Q.; Zhang, D.; Zhang, H.; Xu, C.; Li, X.; Kong, L.; Tao, J.; Cheng, T.; Zhang, R.; Chen, J.; Qiao, L.; Lou, S.; Wang, H.; Chen, C.

    2014-07-01

    New particle formation (NPF) events and their impacts on cloud condensation nuclei (CCN) were investigated using continuous measurements collected in urban Shanghai from 1 to 30 April 2012. During the campaign, NPF occurred in 8 out of the 30 days and enhanced CCN number concentration (NCCN) by a actor of 1.2-1.8, depending on supersaturation (SS). The NPF event on 3 April 2012 was chosen as an example to investigate the NPF influence on CCN activity. In this NPF event, secondary aerosols were produced continuously and increased PM2.5 mass concentration at a~rate of 4.33 μg cm-3 h-1, and the growth rate (GR) and formation rate (FR) were on average 5 nm h-1 and 0.36 cm-3 s-1, respectively. The newly formed particles grew quickly from nucleation mode (10-20 nm) into CCN size range. NCCN increased rapidly at SS of 0.4-1.0% but weakly at SS of 0.2%. Correspondingly, aerosol CCN activities (fractions of activated aerosol particles in total aerosols, NCCN / NCN) were significantly enhanced from 0.24-0.60 to 0.30-0.91 at SS of 0.2-1.0% due to the NPF. On the basis of the κ-Köhler theory, aerosol size distributions and chemical composition measured simultaneously were used to predict NCCN. There was a good agreement between the predicted and measured NCCN (R2 = 0.96, Npredicted / Nmeasured = 1.04). This study reveals that NPF exerts large impacts on aerosol particle abundance and size spectra, thus significantly promotes NCCN and aerosol CCN activity in this urban environment. The GR of NPF is the key factor controlling the newly formed particles to become CCN at all SS levels, whereas the FR is an effective factor only under high SS (e.g. 1.0%) conditions.

  11. Nano-sized aerosol classification, collection and analysis--method development using dental composite materials.

    PubMed

    Bogdan, Axel; Buckett, Mary I; Japuntich, Daniel A

    2014-01-01

    This article presents a methodical approach for generating, collecting, and analyzing nano-size (1-100 nm) aerosol from abraded dental composite materials. Existing aerosol sampling instruments were combined with a custom-made sampling chamber to create and sample a fresh, steady-state aerosol size distribution before significant Brownian coagulation. Morphological, size, and compositional information was obtained by Transmission Electron Microscopy (TEM). To create samples sizes suitable for TEM analysis, aerosol concentrations in the test chamber had to be much higher than one would typically expect in a dental office, and therefore, these results do not represent patient or dental personnel exposures. Results show that nano-size aerosol was produced by the dental drill alone, with and without cooling water drip, prior to abrasion of dental composite. During abrasion, aerosol generation seemed independent of the percent filler load of the restorative material and the operator who generated the test aerosol. TEM investigation showed that "chunks" of filler and resin were generated in the nano-size range; however, free nano-size filler particles were not observed. The majority of observed particles consisted of oil droplets, ash, and graphitic structures.

  12. Dissolution of aerosol particles collected from nuclear facility plutonium production process

    DOE PAGES

    Xu, Ning; Martinez, Alexander; Schappert, Michael Francis; ...

    2015-08-14

    Here, a simple, robust analytical chemistry method has been developed to dissolve plutonium containing particles in a complex matrix. The aerosol particles collected on Marple cascade impactor substrates were shown to be dissolved completely with an acid mixture of 12 M HNO3 and 0.1 M HF. A pressurized closed vessel acid digestion technique was utilized to heat the samples at 130 °C for 16 h to facilitate the digestion. The dissolution efficiency for plutonium particles was 99 %. The resulting particle digestate solution was suitable for trace elemental analysis and isotope composition determination, as well as radiochemistry measurements.

  13. Dissolution of aerosol particles collected from nuclear facility plutonium production process

    SciTech Connect

    Xu, Ning; Martinez, Alexander; Schappert, Michael Francis; Montoya, Dennis Patrick; Martinez, Patrick Thomas; Tandon, Lav

    2015-08-14

    Here, a simple, robust analytical chemistry method has been developed to dissolve plutonium containing particles in a complex matrix. The aerosol particles collected on Marple cascade impactor substrates were shown to be dissolved completely with an acid mixture of 12 M HNO3 and 0.1 M HF. A pressurized closed vessel acid digestion technique was utilized to heat the samples at 130 °C for 16 h to facilitate the digestion. The dissolution efficiency for plutonium particles was 99 %. The resulting particle digestate solution was suitable for trace elemental analysis and isotope composition determination, as well as radiochemistry measurements.

  14. A preliminary analysis of the surface chemistry of atmospheric aerosol particles in a typical urban area of Beijing.

    PubMed

    Zhang, Zhengzheng; Li, Hong; Liu, Hongyan; Ni, Runxiang; Li, Jinjuan; Deng, Liqun; Lu, Defeng; Cheng, Xueli; Duan, Pengli; Li, Wenjun

    2016-09-01

    Atmospheric aerosol particle samples were collected using an Ambient Eight Stage (Non-Viable) Cascade Impactor Sampler in a typical urban area of Beijing from 27th Sep. to 5th Oct., 2009. The surface chemistry of these aerosol particles was analyzed using Static Time of Flight-Secondary Ion Mass Spectrometry (Static TOF-SIMS). The factors influencing surface compositions were evaluated in conjunction with the air pollution levels, meteorological factors, and air mass transport for the sampling period. The results show that a variety of organic ion groups and inorganic ions/ion groups were accumulated on the surfaces of aerosol particles in urban areas of Beijing; and hydrophobic organic compounds with short- or middle-chain alkyl as well as hydrophilic secondary inorganic compounds were observed. All these compounds have the potential to affect the atmospheric behavior of urban aerosol particles. PM1.1-2.1 and PM3.3-4.7 had similar elements on their surfaces, but some molecules and ionic groups demonstrated differences in Time of Flight-Secondary Ion Mass Spectrometry spectra. This suggests that the quantities of elements varied between PM1.1-2.1 and PM3.3-4.7. In particular, more intense research efforts into fluoride pollution are required, because the fluorides on aerosol surfaces have the potential to harm human health. The levels of air pollution had the most significant influence on the surface compositions of aerosol particles in our study. Hence, heavier air pollution was associated with more complex surface compositions on aerosol particles. In addition, wind, rainfall, and air masses from the south also greatly influenced the surface compositions of these urban aerosol particles.

  15. Anthropogenic monoterpene pollution episodes in a forest environment in association with aerosol particles

    NASA Astrophysics Data System (ADS)

    Liao, L.; Taipale, R.; Dal Maso, M.; Ehn, M.; Junninen, H.; Nieminen, T.; Kerminen, V.; Kulmala, M. T.

    2010-12-01

    SMEAR II area. Measured aerosol particle size distributions during the MT pollution episodes indicate that these particles are large enough to act as CCN. The ToF-AMS Case studies show that organic mass dominates the total aerosol masses. Organic mass fraction did not change significantly during episodes, which shows that these aerosol particles have very similar compositions as the regional background aerosol particles. The derived OOA/HOA shows close similarity to particles measured outside MT pollution episodes. DMPS surface plot and monoterpene distributions on March 8th, 2007.

  16. Production Mechanism, Number Concentration, Size Distribution, Chemical Composition, and Optical Properties of Sea Spray Aerosols Workshop, Summer 2012

    SciTech Connect

    Meskhidze, Nicholas

    2013-10-21

    The objective of this workshop was to address the most urgent open science questions for improved quantification of sea spray aerosol-radiation-climate interactions. Sea spray emission and its influence on global climate remains one of the most uncertain components of the aerosol-radiation-climate problem, but has received less attention than other aerosol processes (e.g. production of terrestrial secondary organic aerosols). Thus, the special emphasis was placed on the production flux of sea spray aerosol particles, their number concentration and chemical composition and properties.

  17. Total reflection X-ray fluorescence (TXRF) for direct analysis of aerosol particle samples.

    PubMed

    Bontempi, E; Zacco, A; Benedetti, D; Borgese, L; Colombi, P; Stosnach, H; Finzi, G; Apostoli, P; Buttini, P; Depero, L E

    2010-04-14

    Atmospheric aerosol particles have a great impact on the environment and on human health. Routine analysis of the particles usually involves only the mass determination. However, chemical composition and phases provide fundamental information about the particles' origins and can help to prevent health risks. For example, these particles may contain heavy metals such as Pb, Ni and Cd, which can adversely affect human health. In this work, filter samples were collected in Brescia, an industrial town located in Northern Italy. In order to identify the chemical composition and the phases of the atmospheric aerosols, the samples were analysed by means of total reflection X-ray fluorescence (TXRF) spectrometry with a laboratory instrument and X-ray microdiffraction at Synchrotron Daresbury Laboratories, Warrington (Cheshire, UK). The results are discussed and correlated to identify possible pollution sources. The novelty of this analytical approach is that filter samples for TXRF were analysed directly and did not require chemical pretreatment to leach elements from the aerosol particulates. The results of this study clearly show that TXRF is a powerful technique for the analysis of atmospheric aerosols on 'as-received' filters, thereby leaving samples intact and unaltered for possible subsequent analyses by other methods. In addition, the low detection limits for many elements (low ng/cm2) indicate that this method may hold promise in various application fields, such as nanotechnology.

  18. Molecular Characterization of Brown Carbon in Biomass Burning Aerosol Particles.

    PubMed

    Lin, Peng; Aiona, Paige K; Li, Ying; Shiraiwa, Manabu; Laskin, Julia; Nizkorodov, Sergey A; Laskin, Alexander

    2016-11-01

    Emissions from biomass burning are a significant source of brown carbon (BrC) in the atmosphere. In this study, we investigate the molecular composition of freshly emitted biomass burning organic aerosol (BBOA) samples collected during test burns of sawgrass, peat, ponderosa pine, and black spruce. We demonstrate that both the BrC absorption and the chemical composition of light-absorbing compounds depend significantly on the type of biomass fuels. Common BrC chromophores in the selected BBOA samples include nitro-aromatics, polycyclic aromatic hydrocarbon derivatives, and polyphenols spanning a wide range of molecular weights, structures, and light absorption properties. A number of biofuel-specific BrC chromophores are observed, indicating that some of them may be used as source-specific markers of BrC. On average, ∼50% of the light absorption in the solvent-extractable fraction of BBOA can be attributed to a limited number of strong BrC chromophores. The absorption coefficients of BBOA are affected by solar photolysis. Specifically, under typical atmospheric conditions, the 300 nm absorbance decays with a half-life of ∼16 h. A "molecular corridor" analysis of the BBOA volatility distribution suggests that many BrC compounds in the fresh BBOA have low saturation mass concentration (<1 μg m(-3)) and will be retained in the particle phase under atmospherically relevant conditions.

  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. 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. Heterogeneous particle deaggregation and its implication for therapeutic aerosol performance.

    PubMed

    Xu, Zhen; Mansour, Heidi M; Mulder, Tako; McLean, Richard; Langridge, John; Hickey, Anthony J

    2010-08-01

    Aerosolization performance of dry powder blends of drugs for the treatment of asthma or chronic obstructive pulmonary diseases have been reported in three previous articles. In vitro aerosolization was performed at defined shear stresses (0.624-13.143 N/m(2)). Formulations were characterized aerodynamically and powder aerosol deaggregation equations (PADE) and corresponding linear regression analyses for pharmaceutical aerosolization were applied. Particle deaggregation is the result of overcoming fundamental forces acting at the particle interface. A new method, PADE, describing dry powder formulation performance in a shear stress range has been developed which may allow a fundamental understanding of interparticulate and surface forces. The application of PADE predicts performance efficiency and reproducibility and supports rational design of dry powder formulations. The analogy of aerosol performance with surface molecular adsorption has important implications. Expressions describing surface adsorption were intended to allow elucidation of mechanisms involving surface heterogeneity, lateral interaction, and multilayer adsorption of a variety of materials. By using a similar expression for drug aerosolization performance, it is conceivable that an analogous mechanistic approach to the evaluation of particulate systems would be possible.

  2. 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.

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

    SciTech Connect

    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; Yoder, Richard; Wheeler, Elizabeth K.; Farquar, George R.

    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 use 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.

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

    DOE PAGES

    Harding, Ruth N.; Hara, Christine A.; Hall, Sara B.; ...

    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. Chemical composition and characteristics of ambient aerosols and rainwater residues during Indian summer monsoon: Insight from aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    Chakraborty, Abhishek; Gupta, Tarun; Tripathi, Sachchida N.

    2016-07-01

    Real time composition of non-refractory submicron aerosol (NR-PM1) is measured via Aerosol mass spectrometer (AMS) for the first time during Indian summer monsoon at Kanpur, a polluted urban location located at the heart of Indo Gangetic Plain (IGP). Submicron aerosols are found to be dominated by organics followed by nitrate. Source apportionment of organic aerosols (OA) via positive matrix factorization (PMF) revealed several types of secondary/oxidized and primary organic aerosols. On average, OA are completely dominated by oxidized OA with a very little contribution from biomass burning OA. During rain events, PM1 concentration is decreased almost by 60%, but its composition remains nearly the same. Oxidized OA showed slightly more decrease than primary OAs, probably due to their higher hygroscopicity. The presence of organo nitrates (ON) is also detected in ambient aerosols. Apart from real-time sampling, collected fog and rainwater samples were also analyzed via AMS in offline mode and in the ICP-OES (Inductively coupled plasma - Optical emission spectrometry) for elements. The presence of sea salt, organo nitrates and sulfates has been observed. Rainwater residues are also dominated by organics but their O/C ratios are 15-20% lower than the observed values for ambient OA. Alkali metals such as Ca, Na, K are found to be most abundant in the rainwater followed by Zn. Rainwater residues are also found to be much less oxidized than the aerosols present inside the fog water, indicating presence of less oxidized organics. These findings indicate that rain can act as an effective scavenger of different types of pollutants even for submicron particle range. Rainwater residues also contain organo sulfates which indicate that some portion of the dissolved aerosols has undergone aqueous processing, possibly inside the cloud. Highly oxidized and possibly hygroscopic OA during monsoon period compared to other seasons (winter, post monsoon), indicates that they can act

  7. Physical and chemical characterization of marine atmospheric aerosols over the North and South Pacific Oceans using single particle mass spectrometry

    NASA Astrophysics Data System (ADS)

    Furutani, H.; Jung, J.; Miura, K.; Uematsu, M.

    2010-12-01

    Physical and chemical properties of marine atmospheric aerosols were characterized and compared over the North and South Pacific Ocean during two trans-Pacific cruises (from Japan to Chile and Australia to Japan) during the period of January-June 2009, which cover broad region of Pacific Ocean from 40°N to 55°S and 140°E to 70°W. The measured parameters of aerosol properties were single particle size-resolved chemical composition (D = 100 ~ 1500 nm), cloud condensation nuclei (CCN) and condensation nuclei (CN) concentrations, size distribution from 10 nm to 5 μm, total aerosol nitrate and sulfate concentrations, and filter-based chemical composition. Trace gas concentrations of O3 and CO were also measured to aid air parcel categorization during the cruises. Reflecting larger anthropogenic emission in the Northern Hemisphere, pronounced concentration gradient between the North and South Pacific Ocean was observed for aerosol nitrate, CO, and O3. Aerosol sulfate also showed a similar concentration drop in the equatorial region, relatively higher sulfate concentration was observed in 30°S-40°S and 55°S regions, which was associated with increased aerosol methanesulfonic acid (MSA) concentration but little increase in local marine chlorophyll concentration, suggesting contribution of long-range transported marine biogenic sulfur from the high primary production area over the South Pacific high latitude region. Aerosol chemical classification by single particle chemical analysis revealed that certain aerosol types, such as biomass burning, elemental carbon, and elemental/organic carbon mixed type, were mainly observed in the North Pacific region, while several specific organic aerosol types with abundant aged organic and disulfur composition were identified in the South Pacific region. Further comparison of aerosol properties, aerosol sources, and atmospheric aerosol processing in the North and South Pacific Oceans will be discussed.

  8. Improved Tandem Measurement Techniques for Aerosol Particle Analysis

    NASA Astrophysics Data System (ADS)

    Rawat, Vivek Kumar

    Non-spherical, chemically inhomogeneous (complex) nanoparticles are encountered in a number of natural and engineered environments, including combustion systems (which produces highly non-spherical aggregates), reactors used in gas-phase materials synthesis of doped or multicomponent materials, and in ambient air. These nanoparticles are often highly diverse in size, composition and shape, and hence require determination of property distribution functions for accurate characterization. This thesis focuses on development of tandem mobility-mass measurement techniques coupled with appropriate data inversion routines to facilitate measurement of two dimensional size-mass distribution functions while correcting for the non-idealities of the instruments. Chapter 1 provides the detailed background and motivation for the studies performed in this thesis. In chapter 2, the development of an inversion routine is described which is employed to determine two dimensional size-mass distribution functions from Differential Mobility Analyzer-Aerosol Particle Mass analyzer tandem measurements. Chapter 3 demonstrates the application of the two dimensional distribution function to compute cumulative mass distribution function and also evaluates the validity of this technique by comparing the calculated total mass concentrations to measured values for a variety of aerosols. In Chapter 4, this tandem measurement technique with the inversion routine is employed to analyze colloidal suspensions. Chapter 5 focuses on application of a transverse modulation ion mobility spectrometer coupled with a mass spectrometer to study the effect of vapor dopants on the mobility shifts of sub 2 nm peptide ion clusters. These mobility shifts are then compared to models based on vapor uptake theories. Finally, in Chapter 6, a conclusion of all the studies performed in this thesis is provided and future avenues of research are discussed.

  9. 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.

  10. Bio-aerosols in indoor environment: composition, health effects and analysis.

    PubMed

    Srikanth, Padma; Sudharsanam, Suchithra; Steinberg, Ralf

    2008-01-01

    Bio-aerosols are airborne particles that are living (bacteria, viruses and fungi) or originate from living organisms. Their presence in air is the result of dispersal from a site of colonization or growth. The health effects of bio-aerosols including infectious diseases, acute toxic effects, allergies and cancer coupled with the threat of bioterrorism and SARS have led to increased awareness on the importance of bio-aerosols. The evaluation of bio-aerosols includes use of variety of methods for sampling depending on the concentration of microorganisms expected. There have been problems in developing standard sampling methods, in proving a causal relationship and in establishing threshold limit values for exposures due to the complexity of composition of bio-aerosols, variations in human response to their exposure and difficulties in recovering microorganisms. Currently bio-aerosol monitoring in hospitals is carried out for epidemiological investigation of nosocomial infectious diseases, research into airborne microorganism spread and control, monitoring biohazardous procedures and use as a quality control measure. In India there is little awareness regarding the quality of indoor air, mould contamination in indoor environments, potential source for transmission of nosocomial infections in health care facilities. There is an urgent need to undertake study of indoor air, to generate baseline data and explore the link to nosocomial infections. This article is a review on composition, sources, modes of transmission, health effects and sampling methods used for evaluation of bio-aerosols, and also suggests control measures to reduce the loads of bio-aerosols.

  11. 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

  12. Magnetic targeting of aerosol particles for cancer therapy

    NASA Astrophysics Data System (ADS)

    Ally, Javed; Martin, Benjamin; Behrad Khamesee, Mir; Roa, Wilson; Amirfazli, Alidad

    2005-05-01

    An in vitro model was developed to study and demonstrate the potential and feasibility of magnetically targeted deposition of aerosols for potential applications in lung cancer treatment. Also, a numerical particle tracing model was developed to predict the targeting behavior of the in vitro system; the results from the numerical and experimental studies were in agreement.

  13. Aerosol Size and Chemical Composition in the Canadian High Arctic

    NASA Astrophysics Data System (ADS)

    Chang, R. Y. W.; Hayes, P. L.; Leaitch, W. R.; Croft, B.; O'Neill, N. T.; Fogal, P.; Drummond, J. R.; Sloan, J. J.

    2015-12-01

    Arctic aerosol have a strong annual cycle, with winter months dominated by long range transport from lower latitudes resulting in high mass loadings. Conversely, local emissions are more prominent in the summer months because of the decreased influence of transported aerosol, allowing us to regularly observe both transported and local aerosol. This study will present observations of aerosol chemical composition and particle number size distribution collected at the Polar Environment Artic Research Laboratory and the Alert Global Atmospheric Watch Observatory at Eureka (80N, 86W) and Alert (82N, 62W), Nunavut, respectively. Summer time observations of the number size distribution reveal a persistent mode of particles centered between 30-50 nm, with occasional bursts of smaller particles. The non-refractory aerosol chemical composition, measured by the Canadian Network for the Detection of Atmospheric Change quadrupole aerosol mass spectrometer, is primarily organic, with contributions from both aged and fresher organic aerosol. Factor analysis will be conducted to better understand these sources. The site at Eureka is more susceptible to long range transport since it is at the top of a mountain ridge (610 m above sea level) and will be compared to the site at Alert on an elevated plain (200 m above sea level). This will allow us to determine the relative contributions from processes and sources at the sites at different elevations. Comparisons with aerosol optical depth and GEOS-Chem model output will also be presented to put these surface measurements into context with the overlying and regional atmosphere. Results from this study contribute to our knowledge of aerosol in the high Arctic.

  14. Direct aerosol chemical composition measurements to evaluate the physicochemical differences between controlled sea spray aerosol generation schemes

    NASA Astrophysics Data System (ADS)

    Collins, D. B.; Zhao, D. F.; Ruppel, M. J.; Laskina, O.; Grandquist, J. R.; Modini, R. L.; Stokes, M. D.; Russell, L. M.; Bertram, T. H.; Grassian, V. H.; Deane, G. B.; Prather, K. A.

    2014-07-01

    Controlled laboratory studies of the physical and chemical properties of sea spray aerosol (SSA) must be underpinned by a physically and chemically accurate representation of the bubble mediated production of nascent SSA particles. Since bubble bursting is sensitive to the physicochemical properties of seawater, any important differences in the SSA production mechanism are projected into SSA composition. Using direct chemical measurements of SSA at the single-particle level, this study presents an inter-comparison of three laboratory-based, bubble-mediated SSA production schemes: gas forced through submerged sintered glass filters ("frits"), a pulsed plunging waterfall apparatus, and breaking waves in a wave channel filled with natural seawater. The size-resolved chemical composition of SSA particles produced by breaking waves is more similar to particles produced by the plunging waterfall than sintered glass filters. Aerosol generated by disintegrating foam produced by sintered glass filters contained a larger fraction of organic enriched particles and a different size-resolved elemental composition, especially in the 0.8-2 μm size range. These particles, when dried, had more spherical morphologies compared to the more cubic structure expected for pure NaCl particles, which can be attributed to the presence of additional organic carbon. In addition to an inter-comparison of three SSA production methods, the role of the episodic or "pulsed" nature of the waterfall method utilized in this study on SSA composition was undertaken. In organic-enriched seawater, the continuous operation of the plunging waterfall mechanism resulted in the accumulation of surface foam and an over-expression of organic matter in SSA particles compared to pulsed plunging waterfall. Throughout this set of experiments, comparative differences in the SSA number size distribution were coincident with differences in aerosol composition, indicating that the production mechanism of SSA exerts

  15. 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

  16. A dual-wavelength single particle aerosol fluorescence monitor

    NASA Astrophysics Data System (ADS)

    Kaye, Paul H.; Stanley, Warren R.; Foot, Virginia; Baxter, Karen; Barrington, Stephen J.

    2005-10-01

    Laser diodes and light-emitting diodes capable of continuous sub-300 nm radiation emission will ultimately represent optimal excitation sources for compact and fieldable bio-aerosol monitors. However, until such devices are routinely available and whilst solid-state UV lasers remain relatively expensive, other low-cost sources of UV can offer advantages. This paper describes one such prototype that employs compact xenon discharge UV sources to excite intrinsic fluorescence from individual particles within an ambient aerosol sample. The prototype monitor samples ambient air via a laminar sheathed-flow arrangement such that particles within the sample flow column are rendered in single file as they intersect the beam from a continuous-wave 660nm diode laser. Each individual particle produces a scattered light signal from which an estimate of particle size (down to ~1 um) may be derived. This same signal also initiates the sequential firing (~10 us apart) of two xenon sources which irradiate the particle with UV pulses centred upon ~280 nm and ~370 nm wavelength, optimal for excitation of bio-fluorophores tryptophan and NADH respectively. For each excitation wavelength, fluorescence is detected across two bands embracing the peak emissions of the same bio-fluorophores. Thus, for each particle, a 2-dimensional fluorescence excitation-emission matrix is recorded together with an estimate of particle size. Current measurement rates are up to ~125 particles/s (limited by the xenon recharge time), corresponding to all particles for concentrations up to ~2 x 104 particles/l. Developments to increase this to ~500 particles/s are in hand. Analysis of results from aerosols of E.coli, BG spores, and a variety of non-biological materials are given.

  17. 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.

  18. 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.

  19. Aerosol growth in Titan's ionosphere through particle charging

    NASA Astrophysics Data System (ADS)

    Lavvas, P.; Yelle, R. V.; Koskinen, T.; Bazin, A.; Vuitton, V.; Vigren, E.; Galand, M. F.; Wellbrock, A.; Coates, A. J.; Wahlund, J.; Crary, F.; Snowden, D. S.

    2012-12-01

    Observations of Titan's lower thermosphere and ionosphere by Cassini instruments demonstrate the presence of large mass negative ions of a few thousand amu, and the presence of positive ions up to a few hundred amu [1,2]. The mechanisms though responsible for the production of these large ions have so far remained elusive. A recent Titan flyby that probed deeper layers of Titan's thermosphere than usual, revealed a discrepancy in the observed positive ion and electron density, with the electron density lower than the abundance required to satisfy charge balance [3]. The remaining electron density was found in the form of the large mass negative ions. Aerosols can be charged on interaction with electrons and ions, while this charge can affect the particle coagulation, thus, their subsequent growth. Given the above observations we investigate here the potential role of aerosols in Titan's ionosphere and how this interaction affects the aerosol evolution. This investigation is performed with the use of a model that couples between the ionospheric photochemical evolution and the microphysical growth of aerosols in a self-consistent approach. Our results show that particle charging has an important role in the ionosphere. Most of the produced particles in the ionosphere attain a negative charge. Thus, they act as a sink for the free electrons with the remaining free electron densities consistent with the recent Cassini observations. Being negatively charged, the particles repel each other reducing in this way the coagulation rates and the growth of the aerosols. On the other hand, the negatively charged particles attract the abundant positive ions, which results to enhanced collisions between them. The mass added to the particles by the ions leads to an increase in their size and an increase in the resulting mass flux of the aerosols. Our simulated mass per charge spectra provide excellent fits to the observed positive and negative ion spectra from the Cassini Plasma

  20. Influence of aqueous chemistry on the chemical composition of fog water and interstitial aerosol in Fresno

    NASA Astrophysics Data System (ADS)

    Kim, Hwajin; Ge, Xinlei; Collier, Sonya; Xu, Jianzhong; Sun, Yele; Wang, Youliang; Herckes, Pierre; Zhang, Qi

    2015-04-01

    A measurement study was conducted in the Central Valley (Fresno) of California in January 2010, during which radiation fog events were frequently observed. Fog plays important roles in atmospheric chemistry by scavenging aerosol particles and trace gases and serving as a medium for various aqueous-phase reactions. Understanding the effects of fog on the microphysical and chemical processing of aerosol particles requires detailed information on their chemical composition. In this study, we characterized the chemical composition of fog water and interstitial aerosol particles to study the effects of fog processing on aerosol properties. Fog water samples were collected during the 2010 Fresno campaigns with a Caltech Active Strand Cloud water Collector (CASCC) while interstitial submicron aerosols were characterized in real time with an Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and a scanning Mobility Particle Sizer (SMPS). The fog water samples were later analyzed using the HR-ToF-AMS, ion chromatography, and a total carbon analyzer. The chemical composition and characteristics of interstitial particles during the fog events were compared to those of dissolved inorganic and organic matter in fog waters. Compared to interstitial aerosols, fog water is composed of a higher fraction of ammonium nitrate and oxygenated organics, due to aqueous formation of secondary aerosol species as well as enhanced gas-to-particle partitioning of water soluble species under water rich conditions. Sulfate is formed most efficiently in fog water although its contribution to total dissolved mass is relatively low. The HR-ToF-AMS mass spectra of organic matter in fog water (FOM) are very similar to that of oxygenated organic aerosols (OOA) derived from positive matrix factorization (PMF) of the HR-ToF-AMS spectra of ambient aerosol (r2 = 0.96), but FOM appears to contain a large fraction of acidic functional groups than OOA. FOM is also enriched of

  1. Using Retrieved Aerosol Spectral Properties to Characterize Aerosol Composition and Mixing

    NASA Astrophysics Data System (ADS)

    Li, J.

    2015-12-01

    The spectral dependence of aerosol properties, such as aerosol absorption optical depth (AAOD) and single scattering albedo (SSA), can be used to infer aerosol composition. In particular, aerosol mixtures dominated by dust absorption will have monotonically increasing SSA with wavelength while that dominated by black carbon absorption has monotonically decreasing SSA spectra. However, spectral AAOD and SSA measured in reality may differ from these extreme cases, due to the complicated composition and mixing states. In this study, we use spectral SSA and AAOD retrieved from AERONET measurements, assisted by CALIPSO aerosol type product and Mie calculations, to characterize aerosol mixtures over representative regions. Moreover, in addition to the monotonically increasing or decreasing AAOD and SSA spectra, we find the spectral dependence of these two parameters are frequently peaked (at 675 nm or 870 nm) over several places including East Asia, India, West Africa and South America. We thus suggest that SSA spectral curvature, defined as the negative of the second derivative of SSA as a function of wavelength, can provide additional information on the composition of these aerosol mixtures. Further analysis indicates that moderate mixing of black carbon with dust or organic carbon is mainly responsible for producing the SSA curvature. An optimization scheme was developed to match the observed AAOD and SSA spectra with Mie calculations assuming different aerosol composition and mixing states. Results suggest that while external mixing can explain most of the observed AAOD and SSA spectral dependence, internal mixing or core-shell mode is also likely under many circumstances, such as East Asia during winter and post-monsoon and winter seasons over India. This method offers the potential to quantitatively infer aerosol composition from these spectral measurements of aerosol optical properties.

  2. Predicting the mineral composition of dust aerosols - Part 1: Representing key processes

    NASA Astrophysics Data System (ADS)

    Perlwitz, J. P.; Pérez García-Pando, C.; Miller, R. L.

    2015-10-01

    Soil dust aerosols created by wind erosion are typically assigned globally uniform physical and chemical properties within Earth system models, despite known regional variations in the mineral content of the parent soil. Mineral composition of the aerosol particles is important to their interaction with climate, including shortwave absorption and radiative forcing, nucleation of cloud droplets and ice crystals, heterogeneous formation of sulfates and nitrates, and atmospheric processing of iron into bioavailable forms that increase the productivity of marine phytoplankton. Here, aerosol mineral composition is derived by extending a method that provides the composition of a wet-sieved soil. The extension accounts for measurements showing significant differences between the mineral fractions of the wet-sieved soil and the emitted aerosol concentration. For example, some phyllosilicate aerosols are more prevalent at silt sizes, even though they are nearly absent at these diameters in a soil whose aggregates are dispersed by wet sieving. We calculate the emitted mass of each mineral with respect to size by accounting for the disintegration of soil aggregates during wet sieving. These aggregates are emitted during mobilization and fragmentation of the original undispersed soil that is subject to wind erosion. The emitted aggregates are carried far downwind from their parent soil. The soil mineral fractions used to calculate the aggregates also include larger particles that are suspended only in the vicinity of the source. We calculate the emitted size distribution of these particles using a normalized distribution derived from aerosol measurements. In addition, a method is proposed for mixing minerals with small impurities composed of iron oxides. These mixtures are important for transporting iron far from the dust source, because pure iron oxides are more dense and vulnerable to gravitational removal than most minerals comprising dust aerosols. A limited comparison to

  3. Predicting the Mineral Composition of Dust Aerosols. Part 1; Representing Key Processes

    NASA Technical Reports Server (NTRS)

    Perlwitz, J. P.; Garcia-Pando, C. Perez; Miller, R. L.

    2015-01-01

    Soil dust aerosols created by wind erosion are typically assigned globally uniform physical and chemical properties within Earth system models, despite known regional variations in the mineral content of the parent soil. Mineral composition of the aerosol particles is important to their interaction with climate, including shortwave absorption and radiative forcing, nucleation of cloud droplets and ice crystals, heterogeneous formation of sulfates and nitrates, and atmospheric processing of iron into bioavailable forms that increase the productivity of marine phytoplankton. Here, aerosol mineral composition is derived by extending a method that provides the composition of a wet-sieved soil. The extension accounts for measurements showing significant differences between the mineral fractions of the wetsieved soil and the emitted aerosol concentration. For example, some phyllosilicate aerosols are more prevalent at silt sizes, even though they are nearly absent at these diameters in a soil whose aggregates are dispersed by wet sieving. We calculate the emitted mass of each mineral with respect to size by accounting for the disintegration of soil aggregates during wet sieving. These aggregates are emitted during mobilization and fragmentation of the original undispersed soil that is subject to wind erosion. The emitted aggregates are carried far downwind from their parent soil. The soil mineral fractions used to calculate the aggregates also include larger particles that are suspended only in the vicinity of the source. We calculate the emitted size distribution of these particles using a normalized distribution derived from aerosol measurements. In addition, a method is proposed for mixing minerals with small impurities composed of iron oxides. These mixtures are important for transporting iron far from the dust source, because pure iron oxides are more dense and vulnerable to gravitational removal than most minerals comprising dust aerosols. A limited comparison to

  4. Elemental composition of aerosols in fourteen experiments of the Cloud Condensation Nuclei Workshop

    NASA Technical Reports Server (NTRS)

    Mach, W. H.; Hucek, R. R.

    1981-01-01

    Aeosols were collected with two Ci impactors and analyzed with proton induced X-ray emission (PIXE) for chemical composition and to detect if contamination was present. One of the impactors sampled the generated aerosols; the other impactor sampled droplets from a diffusion cloud chamber. The purpose of the experiments was to test the feasibility of a study of the transfer of chemical elements from the fine particle sizes to the coarse particle sizes, after CCN are activated and cloud droplets are formed. The data indicated that sulfur-containing aerosols did exhibit the expected transfer.

  5. Oxidative aging of mixed oleic acid/sodium chloride aerosol particles

    NASA Astrophysics Data System (ADS)

    Dennis-Smither, Benjamin J.; Miles, Rachael E. H.; Reid, Jonathan P.

    2012-10-01

    Studies of the oxidative aging of single mixed component aerosol particles formed from oleic acid (OL) and sodium chloride over a range of relative humidities (RH) and ozone concentrations by aerosol optical tweezers are reported. The rate of loss of OL and changes in the organic phase volume are directly measured, comparing particles with effloresced and deliquesced inorganic seeds. The kinetics of the OL loss are analyzed and the value of the reactive uptake coefficient of ozone by OL is compared to previous studies. The reaction of OL is accompanied by a decrease in the particle volume, consistent with the evaporation of semivolatile products over a time scale of tens of thousands of seconds. Measurements of the change in the organic phase volume allow the branching ratio to involatile components to be estimated; between 50 and 85% of the initial organic volume remains involatile, depending on ozone concentration. The refractive index (RI) of the organic phase increases during and after evaporation of volatile products, consistent with aging followed by a slow restructuring in particle morphology. The hygroscopicity of the particle and kinetics of the response of the organic phase to changes in RH are investigated. Both size and RI of unoxidized and oxidized particles respond promptly to RH changes with values of the RI consistent with linear mixing rules. Such studies of the simultaneous changes in composition and size of mixed component aerosol provide valuable data for benchmarking kinetic models of heterogeneous atmospheric aging.

  6. Self-assembly of marine exudate particles and their impact on the CCN properties of nascent marine aerosol

    NASA Astrophysics Data System (ADS)

    Schill, S.; Zimmermann, K.; Ryder, O. S.; Campbell, N.; Collins, D. B.; Gianneschi, N.; Bertram, T. H.

    2013-12-01

    Spontaneous self-assembly of marine exudate particles has previously been observed in filtered seawater samples. The chemicophysical properties of these particles may alter the chemical composition and CCN properties of nascent marine aerosol, yet to date simultaneous measurement of seawater exudate particle formation rates and number distributions, with aerosol particle formation rates and CCN activity are lacking. Here, we use a novel Marine Aerosol Reference Tank (MART) system to experimentally mimic a phytoplankton bloom via sequential addition of biological surrogates, including sterol, galactose, lipopolysaccharide, BSA protein, and dipalmitoylphosphatidylcholine. Nascent sea-spray aerosol are generated in the MART system via a continuous plunging waterfall. Exudate particle assembly in the water is monitored via dynamic light scattering (DLS) and transmission electron microscopy (TEM) to obtain both the assembly kinetics of the particles as well as particle number distributions Simultaneous characterization of both particle production rates and super-saturated particle hygroscopicity are also discussed. This study permits analysis of the controlling role of the molecular composition of dissolved organic carbon in setting the production rates of colloidal material in the surface oceans.

  7. 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

  8. Thermophoretic motion of large heated aerosol spherical particles

    NASA Astrophysics Data System (ADS)

    Malai, N. V.; Limanskaya, A. V.; Shchukin, E. R.

    2016-03-01

    The stationary motion of a large spherical aerosol particle in the external field of a temperature gradient in zero gravity is theoretically described using the Stokes approximation and the assumption that the average temperature of the particle surface differs considerably from the temperature of the surrounding gaseous medium. The gas dynamics equations are solved taking into account the power-law temperature dependence of the molecular transport coefficients (viscosity, thermal conductivity) and the density of the gaseous medium. Numerical estimates show that the dependence of the thermophoretic force and velocity on the average temperature of the particle surface is nonlinear.

  9. PD-FiTE - an efficient method for calculating gas / liquid equilibria in atmospheric aerosol particles

    NASA Astrophysics Data System (ADS)

    Topping, D.; Lowe, D.; McFiggans, G.; Barley, M.

    2009-04-01

    Assessing the impact of atmospheric aerosol particles on the environment requires adequate representation of appropriate key processes within large scale models. In the absence of primary particulate material, interactions between the atmospheric gaseous components and particles means that the chemical nature of the particles is largely determined by the availability of condensable gaseous material, such as sulphuric and nitric acids, and by the ambient environmental conditions. Gas to particle mass transfer of semi-volatile components,driven by a difference in equilibrium and actual partial pressures above an aerosol particle, is an important factor in determining the evolving chemical composition of the particle and is necessary for predicting aerosol loading and composition. The design of an appropriate framework required for parameterizations of key variables is challenging. These thermodynamic frameworks are often numerically very complex, resulting in significant computational expense. Three dimensional chemical and aerosol transport models demand that computational expense be kept at a minimum,resulting in a trade-off between accuracy and efficiency. To calculate the equilibrium vapour pressure above a solution requires treatment of solution nonideality. This is manifest through activity coefficients of components pertinent to each condensing specie. However, activity coefficients are complex functions of the solution composition. Parameterisation of activity coefficients provides the main focus of this work largely because reducing the numerical complexity whilst retaining a good level of accuracy is very challenging. The approach presented here, the hybrid Partial Derivative Fitted Taylor Expansion (PDFiTE) (Topping et al 2008), builds on previously reported work, with an aim to derive parameters for an accurate and computationally efficient framework through coupling with a complex thermodynamic model. Such a reduction in complexity is important as it is

  10. Comparison of the DiSCmini aerosol monitor to a handheld condensation particle counter and a scanning mobility particle sizer for submicrometer sodium chloride and metal aerosols

    PubMed Central

    Mills, Jessica B.; Park, Jae Hong; Peters, Thomas M.

    2016-01-01

    We evaluated the robust, lightweight DiSCmini (DM) aerosol monitor for its ability to measure the concentration and mean diameter of submicrometer aerosols. Tests were conducted with monodispersed and polydispersed aerosols composed of two particle types (sodium chloride, NaCl, and spark generated metal particles, which simulate particles found in welding fume) at three different steady-state concentration ranges (Low, <103; Medium, 103–104; and High, >104 particles/cm3). Particle number concentration, lung deposited surface area (LDSA) concentration, and mean size measured with the DM were compared to those measured with reference instruments, a scanning mobility particle sizer (SMPS) and a handheld condensation particle counter (CPC). Particle number concentrations measured with the DM were within 21% of those measured by reference instruments for polydisperse aerosols. Poorer agreement was observed for monodispersed aerosols (±35% for most tests and +130% for 300-nm NaCl). LDSA concentrations measured by the DM were 96% to 155% of those estimated with the SMPS. The geometric mean diameters measured with the DM were within 30% of those measured with the SMPS for monodispersed aerosols and within 25% for polydispersed aerosols (except for the case when the aerosol contained a substantial number of particles larger than 300 nm). The accuracy of the DM is reasonable for particles smaller than 300 nm but caution should be exercised when particles larger than 300 nm are present. PMID:23473056

  11. Mass absorption indices of various types of natural aerosol particles in the infrared.

    PubMed

    Fischer, K

    1975-12-01

    The mass absorption index of aerosol particles has been measured in the 2-17-microm wavelength region. The measurements were performed on films of aerosol particles that were collected by an automatic jet impactor at polluted and various uncontaminated remote sites. All but marine aerosols possess strong absorption bands in the transparent part of the atmospheric long-wave spectrum, indicating marked influence of aerosol particles on the radiation budget of the atmosphere.

  12. Reconciling satellite aerosol optical thickness and surface fine particle mass through aerosol liquid water

    NASA Astrophysics Data System (ADS)

    Nguyen, Thien Khoi V.; Ghate, Virendra P.; Carlton, Annmarie G.

    2016-11-01

    Summertime aerosol optical thickness (AOT) over the southeast U.S. is sharply enhanced over wintertime values. This seasonal pattern is unique and of particular interest because temperatures there have not warmed over the past 100 years. Patterns in surface fine particle mass are inconsistent with satellite reported AOT. In this work, we attempt to reconcile the spatial and temporal distribution of AOT over the U.S. with particle mass measurements at the surface by examining trends in aerosol liquid water (ALW), a particle constituent that scatters radiation and affects satellite AOT but is removed in mass measurements at routine surface monitoring sites. We employ the thermodynamic model ISORROPIAv2.1 to estimate ALW mass concentrations at Interagency Monitoring of PROtected Visual Environments sites using measured ion mass concentrations and North American Regional Reanalysis meteorological data. Excellent agreement between Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations AOT and estimated ALW provides a plausible explanation for the discrepancies in the geographical patterns of AOT and aerosol mass measurements.

  13. Composition and spectral characteristics of ambient aerosol at Mauna Loa Observatory

    SciTech Connect

    Johnson, S.A.; Kumar, R. )

    1991-03-20

    Ambient aerosol particles were sampled continuously with a time resolution of {approximately}4 hours for a period of 8 days at the Mauna Loa Observatory, Hawaii, in August 1986. The samples were analyzed on-site for their chemical composition by attenuated total internal reflection infrared spectroscopy. The infrared absorption spectra of the samples also provided data on aerosol light absorbance characteristics at 9.1 and 10.6 {mu}m - wavelengths of interest in determining aerosol backscatter coefficients for CO{sub 2} lidars. The chemical species in the ambient aerosol varied considerably during this 8-day period. The aerosol was acidic ((NH{sub 4}){sub 3}H(SO{sub 4}){sub 2},NH{sub 4}HSO{sub 4}, or H{sub 2}SO{sub 4}) rather than neutral ((NH{sub 4}){sub 2}SO{sub 4}) for a major fraction of the sampling time. The samples generally showed much higher absorbance at 9.1 {mu}m than at 10.6 {mu}m. Changes in the chemical composition between (NH{sub 4}){sub 2}SO{sub 4} and the more acidic forms were accompanied by substantial changes in the sample's absorbance at 9.1 {mu}m but lesser changes in the absorbance at 10.6 {mu}m. These variations could have a profound effect on backscatter coefficients of atmospheric aerosol particles at CO{sub 2} wavelengths.

  14. Impacts of oxidation aging on secondary organic aerosol formation, particle growth rate, cloud condensation nuclei abundance, and aerosol climate forcing

    NASA Astrophysics Data System (ADS)

    Yu, F.; Luo, G.

    2014-12-01

    Particle composition measurements indicate that organic aerosol (OA) makes up ~20-90% of submicron particulate mass and secondary OA (SOA) accounts for a large fraction (~ 72 ±21%) of these OA masses at many locations around the globe. The volatility changes of secondary organic gases (SOG) associated with oxidation aging as well as the contribution of highly oxidized low volatile SOG (LV-SOG) to the condensational growth of secondary particles have been found to be important in laboratory and field measurements but are poorly represented in global models. A novel scheme to extend the widely used two-product SOA formation model, by adding a third product arising from the oxidation aging (i.e., LV-SOG) and considering the dynamic transfer of mass from higher to lower volatile products, has been developed and implemented into a global chemical transport model (GEOS-Chem) and a community atmosphere model (CESM-CAM5). The scheme requires only minor changes to the existing two-product SOA formation model and is computationally efficient. With the oxidation rate constrained by laboratory measurements, we show that the new scheme predicts a much higher SOA mass concentrations, improving the agreement with aerosol mass spectrometer SOA measurements. The kinetic condensation of LV-SOG on ultrafine particles, simulated by a size-resolved (sectional) advanced particle microphysics (APM) model incorporated into in GEOS-Chem and CAM5, increases the particle growth rate substantially and improves the agreement of simulated cloud condensation nuclei (CCN) concentrations with observations. Based on GEOS-Chem-APM simulations, the new SOA formation scheme increases global mean low troposphere SOA mass concentration by ~130% and CCN abundance by ~ 15%, and optical depth of secondary particles and coated black carbon and primary organic carbon particles by ~10%. As a result, aerosol radiative cooling effect (direct + first indirect) is enhanced by -0.9 W/m2, with large spatial

  15. 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...

  16. Aerosols in Santiago de Chile: A study using receptor modeling with X-ray fluorescence and single particle analysis

    NASA Astrophysics Data System (ADS)

    Rojas, Carlos M.; Artaxo, Paulo; Van Grieken, René

    Between 15 January and 26 February 1987, 51 fine and coarse mode aerosol samples were collected at the Universidad de Santiago de Chile Planetarium using a dichotomous sampler. The samples were analyzed by X-ray fluorescence for up to 17 elements (Mg, Al, Si, P, S, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br and Pb). Aerosol particles were individually studied by Electron Probe Microanalysis (EPMA) and Laser Microprobe Mass Analysis (LAMMA). The data set consisting of aerosol elemental concentrations and meteorological variables was subjected to Principal Factor Analysis (PFA), allowing the identification of six fine mode particle source classes (soil, industrial, sulfate particles, traffic, residual oil, wood-burnings), and five coarse mode particle source classes (soil, industrial, traffic, residual oil, sulfate particles). Both PFA solutions explained about 81 and 90% of the total variance in the data set, respectively. The regression of elemental mass concentrations on the Absolute Principal Factor Scores allowed the estimation of the contribution of the different source classes to the Santiago aerosol. Within the fine fraction, secondary SO 42- particles were responsible for about 49% of the fine mode aerosol mass concentration, while 26, 13, 6.4 and 5.6% were attributed to wood-burning/car exhausts, residual oil combustion, soil dust/metallurgical, and soil dust/wood-burning releases, respectively. The coarse fraction source apportionment was mainly dominated by soil dust, accounting for 74% of the coarse mode aerosol mass concentration. A composite of soil dust and industrial release accounted for 13%; a composite of secondary sulfates contributed with 9%; a composite of soil dust and automotive emissions, and secondary sulfates were responsible for 4 and 0.03% of the coarse aerosol mass concentration, respectively. EPMA results are in satisfactory agreement with those from the bulk analysis and allowed the identification of eight particle types in both fine

  17. REDOX AND ELECTROPHILIC PROPERTIES OF VAPOR- AND PARTICLE-PHASE COMPONENTS OF AMBIENT AEROSOLS

    PubMed Central

    Eiguren-Fernandez, Arantzazu; Shinyashiki, Masaru; Schmitz, Debra A.; DiStefano, Emma; Hinds, William; Kumagai, Yoshito; Cho, Arthur K.; Froines, John R.

    2010-01-01

    Particulate matter (PM) has been the primary focus of studies aiming to understand the relationship between the chemical properties of ambient aerosols and adverse health effects. Size and chemical composition of PM have been linked to their oxidative capacity which has been postulated to promote or exacerbate pulmonary and cardiovascular diseases. But in the last few years, new studies have suggested that volatile and semivolatile components may also contribute to many adverse health effects. The objectives of this study were: i) assess for the first time the redox and electrophilic potential of vapor-phase components of ambient aerosols, and ii) evaluate the relative contributions of particle- and vapor-fractions to the hazard of a given aerosol. To achieve these objectives vapor- and particle-phase samples collected in Riverside (CA) were subjected to three chemical assays to determine their redox and electrophilic capacities. The results indicate that redox active components are mainly associated with the particle-phase, while electrophilic compounds are found primarily in the vapor-phase. Vapor-phase organic extracts were also capable of inducing the stress responding protein, heme-oxygenase-1 (HO-1), in RAW264.7 murine macrophages. These results demonstrate the importance of volatile components in the overall oxidative and electrophilic capacity of aerosols, and point out the need for inclusion of vapors in future health and risk assessment studies. PMID:20152964

  18. Aerosol and CCN properties at Princess Elisabeth station, East Antarctica: seasonality, new particle formation events and properties around precipitation events

    NASA Astrophysics Data System (ADS)

    Mangold, Alexander; Laffineur, Quentin; De Backer, Hugo; Herenz, Paul; Wex, Heike; Gossart, Alexandra; Souverijns, Niels; Gorodetskaya, Irina; Van Lipzig, Nicole

    2016-04-01

    Since 2010, several complementary ground-based instruments for measuring the aerosol composition of the Antarctic atmosphere have been operated at the Belgian Antarctic research station Princess Elisabeth, in Dronning Maud Land, East Antarctica (71.95° S, 23.35° E, 1390 m asl.). In addition, three ground-based remote sensing instruments for cloud and precipitation observations have been installed for continuous operation, including a ceilometer (cloud base height, type, vertical extent), a 24 Ghz micro-rain radar (vertical profiles of radar effective reflectivity and Doppler velocity), and a pyrometer (cloud base temperature). The station is inhabited from November to end of February and operates under remote control during the other months. In this contribution, the general aerosol and cloud condensation nuclei (CCN) properties will be described with a special focus on new particle formation events and around precipitation events. New particle formation events are important for the atmospheric aerosol budget and they also show that aerosols are not only transported to Antarctica but are also produced there, also inland. Aerosols are essential for cloud formation and therefore also for precipitation, which is the only source for mass gain of the Antarctic ice sheet. Measured aerosol properties comprise size distribution, total number, total mass concentration, mass concentration of light-absorbing aerosol and absorption coefficient and total scattering coefficient. In addition, a CCN counter has been operated during austral summers 2013/14, 2014/15 and 2015/16. The baseline total number concentration N-total was around some hundreds of particles/cm3. During new particle formation events N-total increased to some thousands of particles/cm3. Simultaneous measurements of N-total, size distribution and CCN number revealed that mostly the number of particles smaller than 100 nm increased and that the concentration of cloud condensation nuclei increased only very

  19. A role of aerosol particles in forming urban skyglow and skyglow from distant cities

    NASA Astrophysics Data System (ADS)

    Kocifaj, Miroslav; Kómar, Ladislav

    2016-05-01

    Aerosol particles may represent the largest uncertainty about skyglow change in many locations under clear-sky conditions. This is because aerosols are ubiquitous in the atmosphere and influence the ground-reaching radiation in different ways depending on their concentrations, origins, shapes, sizes, and compositions. Large particles tend to scatter in Fraunhofer diffraction regime, while small particles can be treated in terms of Rayleigh formalism. However, the role of particle microphysics in forming the skyglow still remains poorly quantified. We have shown in this paper that the chemistry is somehow important for backscattering from large particles that otherwise work as efficient attenuators of light pollution if composed of absorbing materials. The contribution of large particles to the urban skyglow diminishes as they become more spherical in shape. The intensity of backscattering from non-absorbing particles is more-or-less linearly decreasing function of particle radius even if number size distribution is inversely proportional to the fourth power of particle radius. This is due to single particle backscattering that generally increases steeply as the particle radius approaches large values. Forward scattering depends on the particle shape but is independent of the material composition, thus allowing for a simplistic analytical model of skyglow from distant cities. The model we have developed is based on mean value theorem for integrals and incorporates the parametrizable Garstang's emission pattern, intensity decay along optical beam path, and near-forward scattering in an atmospheric environment. Such model can be used by modellers and experimentalists for rapid estimation of skyglow from distant light sources.

  20. Aerosol Sampling System for Collection of Capstone Depleted Uranium Particles in a High-Energy Environment

    SciTech Connect

    Holmes, Thomas D.; Guilmette, Raymond A.; Cheng, Yung-Sung; Parkhurst, MaryAnn; Hoover, Mark D.

    2009-03-01

    The Capstone Depleted Uranium Aerosol Study was undertaken to obtain aerosol samples resulting from a kinetic-energy cartridge with a large-caliber depleted uranium (DU) penetrator striking an Abrams or Bradley test vehicle. The sampling strategy was designed to (1) optimize the performance of the samplers and maintain their integrity in the extreme environment created during perforation of an armored vehicle by a DU penetrator, (2) collect aerosols as a function of time post-impact, and (3) obtain size-classified samples for analysis of chemical composition, particle morphology, and solubility in lung fluid. This paper describes the experimental setup and sampling methodologies used to achieve these objectives. Custom-designed arrays of sampling heads were secured to the inside of the target in locations approximating the breathing zones of the vehicle commander, loader, gunner, and driver. Each array was designed to support nine filter cassettes and nine cascade impactors mounted with quick-disconnect fittings. Shielding and sampler placement strategies were used to minimize sampler loss caused by the penetrator impact and the resulting fragments of eroded penetrator and perforated armor. A cyclone train was used to collect larger quantities of DU aerosol for chemical composition and solubility. A moving filter sample was used to obtain semicontinuous samples for depleted uranium concentration determination. Control for the air samplers was provided by five remotely located valve control and pressure monitoring units located inside and around the test vehicle. These units were connected to a computer interface chassis and controlled using a customized LabVIEW engineering computer control program. The aerosol sampling arrays and control systems for the Capstone study provided the needed aerosol samples for physicochemical analysis, and the resultant data were used for risk assessment of exposure to DU aerosol.

  1. Aerosol sampling system for collection of Capstone depleted uranium particles in a high-energy environment.

    PubMed

    Holmes, Thomas D; Guilmette, Raymond A; Cheng, Yung Sung; Parkhurst, Mary Ann; Hoover, Mark D

    2009-03-01

    The Capstone Depleted Uranium (DU) Aerosol Study was undertaken to obtain aerosol samples resulting from a large-caliber DU penetrator striking an Abrams or Bradley test vehicle. The sampling strategy was designed to (1) optimize the performance of the samplers and maintain their integrity in the extreme environment created during perforation of an armored vehicle by a DU penetrator, (2) collect aerosols as a function of time post perforation, and (3) obtain size-classified samples for analysis of chemical composition, particle morphology, and solubility in lung fluid. This paper describes the experimental setup and sampling methodologies used to achieve these objectives. Custom-designed arrays of sampling heads were secured to the inside of the target in locations approximating the breathing zones of the crew locations in the test vehicles. Each array was designed to support nine filter cassettes and nine cascade impactors mounted with quick-disconnect fittings. Shielding and sampler placement strategies were used to minimize sampler loss caused by the penetrator impact and the resulting fragments of eroded penetrator and perforated armor. A cyclone train was used to collect larger quantities of DU aerosol for measurement of chemical composition and solubility. A moving filter sample was used to obtain semicontinuous samples for DU concentration determination. Control for the air samplers was provided by five remotely located valve control and pressure monitoring units located inside and around the test vehicle. These units were connected to a computer interface chassis and controlled using a customized LabVIEW engineering computer control program. The aerosol sampling arrays and control systems for the Capstone study provided the needed aerosol samples for physicochemical analysis, and the resultant data were used for risk assessment of exposure to DU aerosol.

  2. Visibility-reducing organic aerosols in the vicinity of Grand Canyon National Park: 2. Molecular composition

    SciTech Connect

    Mazurek, M.A.; Newman, L.; Daum, P.H.

    1995-12-31

    In this study we examine the molecular organic constituents (C8 to C40 lipid compounds) collected as aerosol from two sites located in Grand Canyon National Park during summer ambient conditions. Of special interest are molecular species which serve as tracers for possible sources of the observed aerosol organic matter. Ambient samples were collected from Hopi Point (rim site) and from Indian Gardens (in-canyon site) as fine (dp< 2.1 =B5m) and total particle samples. The samples were grouped into fine particle and total particle monthly composites to provide sufficient material for molecular marker analysis then analyzed by capillary gas chromatography/mass spectrometry (GUMS), The molecular constituents of each aerosol composite were screened for key tracer compounds using a computerized data reduction method that was based on molecular ion fragment identification. Comparisons were made to a reference database that included molecular information obtained from authentic sources of primary organic aerosol emissions. Emission sources studied included vehicular exhaust, as well as local sources at the Grand Canyon which included soil dust, wood smoke, and particles from vegetation indigenous to the two Grand Canyon sampling sites. Our results show that summertime ambient aerosols contain many organic molecular compounds which can be related directly to the local vegetation. Another major component found in all samples consists of highly oxidized organic species which are not emitted directly from local primary organic aerosol source types. These oxidized species are thought to be secondary organic aerosols that originate from photochemical transformations involving either locally emitted primary organic compounds or transported aged emissions from source regions upwind of the Grand Canyon.

  3. 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.

  4. 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

  5. Differences in physical chemistry and dissolution rate of solid particle aerosols from solution pressurised inhalers.

    PubMed

    Buttini, Francesca; Miozzi, Michele; Balducci, Anna Giulia; Royall, Paul G; Brambilla, Gaetano; Colombo, Paolo; Bettini, Ruggero; Forbes, Ben

    2014-04-25

    Solution composition alters the dynamics of beclomethasone diproprionate (BDP) particle formation from droplets emitted by pressurised metered dose inhalers (pMDIs). The hypothesis that differences in inhaler solutions result in different solid particle physical chemistry was tested using a suite of complementary calorimetric techniques. The atomisation of BDP-ethanol solutions from commercial HFA-pMDI produced aerodynamically-equivalent solid particle aerosols. However, differences in particle physico-chemistry (morphology and solvate/clathrate formation) were detected by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and supported by hot stage microscopy (HSM). Increasing the ethanol content of the formulation from 8 to 12% (w/w), which retards the evaporation of propellant and slows the increase in droplet surface viscosity, enhanced the likelihood of particles drying with a smooth surface. The dissolution rate of BDP from the 12% (w/w) ethanol formulation-derived particles (63% dissolved over 120 min) was reduced compared to the 8% (w/w) ethanol formulation-derived particles (86% dissolved over 120 min). The addition of 0.01% (w/w) formoterol fumarate or 1.3% (w/w) glycerol to the inhaler solution modified the particles and reduced the BDP dissolution rate further to 34% and 16% dissolved in 120 min, respectively. These data provide evidence that therapeutic aerosols from apparently similar inhaler products, including those with similar aerodynamic performance, may behave non-equivalently after deposition in the lungs.

  6. Extractive Electrospray Ionization Mass Spectrometry of Heterogeneous Particles: Implications for Applications to Complex Atmospheric Aerosol

    NASA Astrophysics Data System (ADS)

    Longin, T.; Waring-Kidd, C.; Wingen, L. M.; Lyster, K.; Anderson, C.; Kumbhani, S.; Finlayson-Pitts, B. J.

    2015-12-01

    Extractive electrospray ionization mass spectrometry (EESI-MS) is a direct, real time technique for obtaining mass spectra of gases, liquid droplets, solid particles, and aerosols with little sample processing. EESI-MS involves the interaction of charged electrospray droplets with a separate spray containing the analyte of interest, but the exact mechanism by which the solvent droplets extract analyte from the sample is unclear. Possible mechanisms include complete coalescence of the sample particle with the solvent droplet in which all of the analyte is incorporated into the solvent or a more temporary interaction such that only some of the analyte is transferred to the solvent. Previous studies of the mechanism of EESI-MS on homogeneous particles indicate that both mechanisms are possible. We studied the behavior of EESI-MS toward heterogeneous particles created by coating NaCl particles with various thicknesses of organic diacids. Our results indicate that the signal strength depends on the solubility of the organic acid in the electrospray solvent, in agreement with previous studies, and also that the outer 10-15 nm of the particles are most susceptible to extraction into the electrospray droplets. Our results combined with those of previous studies suggest that the mass spectra obtained with EESI will not necessarily reflect the overall particle composition, especially for particles that are spatially inhomogeneous, and hence caution in interpretation of the data is advised for application to complex atmospheric aerosol.

  7. Organic Composition and Morphology of Sea Spray Aerosols as a Function of Biological Life during IMPACTS

    NASA Astrophysics Data System (ADS)

    Pham, D.; Moffet, R.; Fraund, M. W.; O'Brien, R.; Laskina, O.; Prather, K. A.; Grassian, V. H.; Beall, C.; Wang, X.; Forestieri, S.; Cappa, C. D.

    2015-12-01

    Aerosols influence climate by directly reflecting or absorbing sunlight, or indirectly by affecting clouds. A major source of aerosols is from oceanic wave breaking. Due to their complexity, the effects of marine aerosol on climate are uncertain. To provide more detailed measurements of the chemical composition of marine aerosols, Scanning Transmission X-Ray Microscopy coupled with Near Edge X-Ray Absorption Fine Structure (SXTM-NEXAFS) was used to give spatially resolved molecular information for carbon and oxygen. Application of STXM/NEXAFS to particles collected during a mesocosm study using a unique wave channel facility to generate aerosols shows that the organic volume fraction of aerosols at the aerodynamic diameter size range of 0.18-0.32 μm are a direct function of the biological activity in the sea water. Aerosol organic volume fraction increased from 0.32 for particles generated from seawater containing low biolife to 0.49 and 0.40 for particles produced during phytoplankton blooms. However, the organic volume fraction of aerosols at the aerodynamic diameter size range of 0.56-1 μm did not change with biological activity. Measurements also show that different types of organics can concentrate into aerosols depending on the enzyme activity expressed at the time. Enhanced spectral signatures for aliphatic hydrocarbons were observed during the first phytoplankton bloom compared to a second phytoplankton bloom occurring directly thereafter. The decreased signature of aliphatic organics in the second phytoplankton bloom was correlated with increased lipase activity from heterobacteria. Organic aggregates having similar morphology also differ in composition from their carbon spectra from the two blooms. For July 17, organic aggregates were much richer in hydrocarbons, which showed a remarkably intense C-H absorbance and a broad C-C absorbance. Organic aggregates observed for July 26-27, did not have the C-H and C-C signatures, but contained more polar

  8. Liquid-liquid phase separation in aerosol particles: Imaging at the Nanometer Scale

    SciTech Connect

    O'Brien, Rachel; Wang, Bingbing; Kelly, Stephen T.; Lundt, Nils; You, Yuan; Bertram, Allan K.; Leone, Stephen R.; Laskin, Alexander; Gilles, Mary K.

    2015-04-21

    Atmospheric aerosols can undergo phase transitions including liquid-liquid phase separation (LLPS) while responding to changes in the ambient relative humidity (RH). Here, we report results of chemical imaging experiments using environmental scanning electron microscopy (ESEM) and scanning transmission x-ray microscopy (STXM) to investigate the LLPS of micron sized particles undergoing a full hydration-dehydration cycle. Internally mixed particles composed of ammonium sulfate (AS) and either: limonene secondary organic carbon (LSOC), a, 4-dihydroxy-3-methoxybenzeneaceticacid (HMMA), or polyethylene glycol (PEG-400) were studied. Events of LLPS with apparent core-shell particle morphology were observed for all samples with both techniques. Chemical imaging with STXM showed that both LSOC/AS and HMMA/AS particles were never homogeneously mixed for all measured RH’s above the deliquescence point and that the majority of the organic component was located in the shell. The shell composition was estimated as 65:35 organic: inorganic in LSOC/AS and as 50:50 organic: inorganic for HMMA/AS. PEG-400/AS particles showed fully homogeneous mixtures at high RH and phase separated below 89-92% RH with an estimated 50:50% organic to inorganic mix in the shell. These two chemical imaging techniques are well suited for in-situ analysis of the hygroscopic behavior, phase separation, and surface composition of collected ambient aerosol particles.

  9. Accommodation coefficient of HOBr on deliquescent sodium bromide aerosol particles

    NASA Astrophysics Data System (ADS)

    Wachsmuth, M.; Gäggeler, H. W.; von Glasow, R.; Ammann, M.

    2002-06-01

    Uptake of HOBr on sea salt aerosol, sea salt brine or ice is believed to be a key process providing a source of photolabile bromine (Br2) and sustaining ozone depletion cycles in the Arctic troposphere. In the present study, uptake of HOBr on sodium bromide (NaBr) aerosol particles was investigated at an extremely low HOBr concentration of 300 cm-3 using the short-lived radioactive isotopes 83-86Br. Under these conditions, at maximum one HOBr molecule was taken up per particle. The rate of uptake was clearly limited by the mass accommodation coefficient, which was calculated to be 0.6 ± 0.2. This value is a factor of 10 larger than estimates used in earlier models. The atmospheric implications are discussed using the box model "MOCCA'', showing that the increase of the accommodation coefficient of HOBr by a factor of 10 only slightly affects net ozone loss, but significantly increases chlorine release.

  10. 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

  11. 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.

  12. The real part of the refractive indices and effective densities for chemically segregated ambient aerosols in Guangzhou by a single particle aerosol mass spectrometer

    NASA Astrophysics Data System (ADS)

    Zhang, G.; Bi, X.; Qiu, N.; Han, B.; Lin, Q.; Peng, L.; Chen, D.; Wang, X.; Peng, P.; Sheng, G.; Zhou, Z.

    2015-12-01

    Microphysical properties of atmospheric aerosols are essential to better evaluate their radiative forcing. This paper first presents an estimate of the real part of the refractive indices (n) and effective densities (ρeff) of chemically segregated atmospheric aerosols in China. Vacuum aerodynamic diameter, chemical compositions, and light scattering intensities of individual particles were simultaneously measured by a single particle aerosol mass spectrometer (SPAMS) during fall of 2012 in Guangzhou. On the basis of Mie theory, n and ρeff were estimated for 17 particle types in four categories: organics (OC), elemental carbon (EC), internally mixed EC and OC (ECOC), and metal rich, respectively. Results indicate the presence of spherical or nearly spherical shape for majority of particle types, whose partial scattering cross section vs. sizes were well fitted to Mie theoretical modeling results. While sharing n in a narrow range (1.47-1.53), majority of particle types exhibited a wide range of ρeff (0.87-1.51 g cm-3). OC group is associated with the lowest ρeff (0.87-1.07 g cm-3), while metal rich group with the highest ones (1.29-1.51 g cm-3). It is noteworthy that a specific EC type exhibits a complex scattering curve vs. size due to the presence of both compact and irregularly shape particles. Overall, the results on detailed relationship between physical and chemical properties benefits future researches on the impact of aerosols on visibility and climate.

  13. Gap-flow Mediated Transport of Pollution to a Remote Coastal Site: Effects upon Aerosol Composition

    NASA Astrophysics Data System (ADS)

    Cornwell, G.; Martin, A.; Petters, M.; Prather, K. A.; Taylor, H.; Rothfuss, N.; DeMott, P. J.; Kreidenweis, S. M.

    2015-12-01

    During the CalWater 2015 field campaign, observations of aerosol size, concentration, chemical composition, and cloud activity were made at Bodega Bay, CA on the remote California coast. Strong anthropogenic influence on air quality, aerosol physicochemical properties and cloud activity was observed at Bodega Bay during periods of special meteorological conditions, known as Petaluma Gap Flow, in which air from California's interior is transported to the coast. This study utilizes single particle mass spectrometry, along with aerosol physical and chemical measurements and meteorological measurements to show that the dramatic change in aerosol properties is strongly related to regional meteorology and anthropogenically-influenced chemical processes in California's Central Valley. The change in airmass properties from those typical of a remote marine environment to properties of a continental regime has impacts on atmospheric radiative balance and cloud formation that must be accounted for in regional climate simulation.

  14. 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

  15. 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.

  16. Aerosol particles from tropical convective systems: 2. Cloud bases

    NASA Astrophysics Data System (ADS)

    Kojima, Tomoko; Buseck, Peter R.; Reeves, J. Michael

    2005-05-01

    Aerosol particles were collected at the altitudes of cloud bases during the Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment (CRYSTAL-FACE) and analyzed using transmission electron microscopy. The particles consist of ammonium sulfate (45-90% by number), sea salt (5-45%), mineral dust (1-20%), and anthropogenic materials such as soot and fly ash (<3%). Ammonium sulfate particles have rather uniform, submicron sizes (mostly 0.5 μm across). Sea-salt particles are larger, apparently having been deliquesced. However, submicron particles are also common. Many contain Na and mixed cation sulfates in addition to NaCl. Mineral dust consists largely of tabular clay particles. Samples from the 28 July flight contain much mineral dust, probably because of transport from the Saharan Desert. Aggregates of sea salt and mineral dust, ammonium sulfate, and soot particles are common. Such mixed aggregates are especially abundant in in-cloud samples. Cirrus samples from CRYSTAL-FACE contain many H2SO4 droplets (Kojima et al., 2004), but acidic sulfate particles are rare at the altitudes of cloud bases. H2SO4 probably formed at higher altitudes through oxidation of SO2 in cloud droplets. Sea salt and mineral dust have been reported to be abundant in cloud particles collected using a counterflow virtual impactor (Cziczo et al., 2004), suggesting that these particles were incorporated into the convective systems from the cloud bases and akted as ice nuclei while being vertically transported.

  17. Diurnal Cycles of Aerosol Optical Properties at Pico Tres Padres, Mexico City: Evidences for Changes in Particle Morphology and Secondary Aerosol Formation

    NASA Astrophysics Data System (ADS)

    Mazzoleni, C.; Dubey, M.; Chakrabarty, R.; Moosmuller, H.; Onasch, T.; Zavala, M.; Herndon, S.; Kolb, C.

    2007-12-01

    Aerosol optical properties affect planetary radiative balance and depend on chemical composition, size distribution, and morphology. During the MILAGRO field campaign, we measured aerosol absorption and scattering in Mexico City using the Los Alamos aerosol photoacoustic (LAPA) instrument operating at 781 nm. The LAPA was mounted on-board the Aerodyne Research Inc. mobile laboratory, which hosted a variety of gaseous and aerosol instruments. During the campaign, the laboratory was moved to different sites, capturing spatial and temporal variability. Additionally, we collected ambient aerosols on Nuclepore filters for scanning electron microscopy (SEM) analysis. SEM images of selected filters were taken to study particle morphology. Between March 7th and 19th air was sampled at the top of Pico Tres Padres, a mountain on the north side of Mexico City. Aerosol absorption and scattering followed diurnal patterns related to boundary layer height and solar insulation. We report an analysis of aerosol absorption, scattering, and morphology for three days (9th, 11th and 12th of March 2006). The single scattering albedo (SSA, ratio of scattering to total extinction) showed a drop in the tens-of-minutes-to-hour time frame after the boundary layer grew above the sampling site. Later in the day the SSA rose steadily reaching a maximum in the afternoon. The SEM images showed a variety of aerosol shapes including fractal-like aggregates, spherical particles, and other shapes. The absorption correlated with the CO2 signal and qualitatively with the fraction of fractal-like particles to the total particle count. In the afternoon the SSA qualitatively correlated with a relative increase in spherical particles and total particle count. These observed changes in optical properties and morphology can be explained by the dominant contribution of freshly emitted particles in the morning and by secondary particle formation in the afternoon. SSA hourly averaged values ranged from ~0.63 in

  18. Simultaneous ion luminescence imaging and spectroscopy of individual aerosol particles with external proton or helium microbeams

    NASA Astrophysics Data System (ADS)

    Kada, Wataru; Satoh, Takahiro; Yokoyama, Akihito; Koka, Masashi; Kamiya, Tomihiro

    2014-08-01

    Simultaneous microscopic imaging and spectroscopy of individual aerosol particles were performed with an external microbeam. Visible luminescence induced by the external microbeam was successfully used as a probe to detect organic contaminants in the targets. Combined ion luminescence (IL)/particle-induced X-ray emission (PIXE) analysis of the aerosol targets revealed microscopic chemical and elemental composition distributions under ambient atmospheric conditions. The simple confocal micro-optics for the IL spectroscopy and microscopic imaging were sufficiently sensitive for detecting these molecules at sub-parts per million concentrations and at a wavelength resolution of less than 5 nm. The IL spectra were monitored to prevent severe damage to the samples. Furthermore, our IL system has the advantage that it is simple to add to a conventional micro-PIXE system.

  19. Individual aerosol particles in and below clouds along a Mt. Fuji slope: Modification of sea-salt-containing particles by in-cloud processing

    NASA Astrophysics Data System (ADS)

    Ueda, S.; Hirose, Y.; Miura, K.; Okochi, H.

    2014-02-01

    Sizes and compositions of atmospheric aerosol particles can be altered by in-cloud processing by absorption/adsorption of gaseous and particulate materials and drying of aerosol particles that were formerly activated as cloud condensation nuclei. To elucidate differences of aerosol particles before and after in-cloud processing, aerosols were observed along a slope of Mt. Fuji, Japan (3776 m a.s.l.) during the summer in 2011 and 2012 using a portable laser particle counter (LPC) and an aerosol sampler. Aerosol samples for analyses of elemental compositions were obtained using a cascade impactor at top-of-cloud, in-cloud, and below-cloud altitudes. To investigate composition changes via in-cloud processing, individual particles (0.5-2 μm diameter) of samples from five cases (days) collected at different altitudes under similar backward air mass trajectory conditions were analyzed using a transmission electron microscope (TEM) equipped with an energy dispersive X-ray analyzer. For most cases (four cases), most particles at all altitudes mainly comprised sea salts: mainly Na with some S and/or Cl. Of those, in two cases, sea-salt-containing particles with Cl were found in below-cloud samples, although sea-salt-containing particles in top-of-cloud samples did not contain Cl. This result suggests that Cl in the sea salt was displaced by other cloud components. In the other two cases, sea-salt-containing particles on samples at all altitudes were without Cl. However, molar ratios of S to Na (S/Na) of the sea-salt-containing particles of top-of-cloud samples were higher than those of below-cloud samples, suggesting that sulfuric acid or sulfate was added to sea-salt-containing particles after complete displacement of Cl by absorption of SO2 or coagulation with sulfate. The additional volume of sulfuric acid in clouds for the two cases was estimated using the observed S/Na values of sea-salt-containing particles. The estimation revealed that size changes by in

  20. Constraining the atmospheric composition of the day-night terminators of HD 189733b: Atmospheric retrieval with aerosols

    SciTech Connect

    Lee, Jae-Min; Irwin, Patrick G. J.; Fletcher, Leigh N.; Barstow, Joanna K.; Heng, Kevin

    2014-07-01

    A number of observations have shown that Rayleigh scattering by aerosols dominates the transmission spectrum of HD 189733b at wavelengths shortward of 1 μm. In this study, we retrieve a range of aerosol distributions consistent with transmission spectroscopy between 0.3-24 μm that were recently re-analyzed by Pont et al. To constrain the particle size and the optical depth of the aerosol layer, we investigate the degeneracies between aerosol composition, temperature, planetary radius, and molecular abundances that prevent unique solutions for transit spectroscopy. Assuming that the aerosol is composed of MgSiO{sub 3}, we suggest that a vertically uniform aerosol layer over all pressures with a monodisperse particle size smaller than about 0.1 μm and an optical depth in the range 0.002-0.02 at 1 μm provides statistically meaningful solutions for the day/night terminator regions of HD 189733b. Generally, we find that a uniform aerosol layer provide adequate fits to the data if the optical depth is less than 0.1 and the particle size is smaller than 0.1 μm, irrespective of the atmospheric temperature, planetary radius, aerosol composition, and gaseous molecules. Strong constraints on the aerosol properties are provided by spectra at wavelengths shortward of 1 μm as well as longward of 8 μm, if the aerosol material has absorption features in this region. We show that these are the optimal wavelengths for quantifying the effects of aerosols, which may guide the design of future space observations. The present investigation indicates that the current data offer sufficient information to constrain some of the aerosol properties of HD189733b, but the chemistry in the terminator regions remains uncertain.

  1. Molecular Composition and Volatility of Organic Aerosol in the Southeastern U.S.: Implications for IEPOX Derived SOA.

    PubMed

    Lopez-Hilfiker, F D; Mohr, C; D'Ambro, E L; Lutz, A; Riedel, T P; Gaston, C J; Iyer, S; Zhang, Z; Gold, A; Surratt, J D; Lee, B H; Kurten, T; Hu, W W; Jimenez, J; Hallquist, M; Thornton, J A

    2016-03-01

    We present measurements as part of the Southern Oxidant and Aerosol Study (SOAS) during which atmospheric aerosol particles were comprehensively characterized. We present results utilizing a Filter Inlet for Gases and AEROsol coupled to a chemical ionization mass spectrometer (CIMS). We focus on the volatility and composition of isoprene derived organic aerosol tracers and of the bulk organic aerosol. By utilizing the online volatility and molecular composition information provided by the FIGAERO-CIMS, we show that the vast majority of commonly reported molecular tracers of isoprene epoxydiol (IEPOX) derived secondary organic aerosol (SOA) is derived from thermal decomposition of accretion products or other low volatility organics having effective saturation vapor concentrations <10(-3) μg m(-3). In addition, while accounting for up to 30% of total submicrometer organic aerosol mass, the IEPOX-derived SOA has a higher volatility than the remaining bulk. That IEPOX-SOA, and more generally bulk organic aerosol in the Southeastern U.S. is comprised of effectively nonvolatile material has important implications for modeling SOA derived from isoprene, and for mechanistic interpretations of molecular tracer measurements. Our results show that partitioning theory performs well for 2-methyltetrols, once accretion product decomposition is taken into account. No significant partitioning delays due to aerosol phase or viscosity are observed, and no partitioning to particle-phase water or other unexplained mechanisms are needed to explain our results.

  2. Variations of the aerosol concentration and chemical composition over the arid steppe zone of Southern Russia in summer

    NASA Astrophysics Data System (ADS)

    Artamonova, M. S.; Gubanova, D. P.; Iordanskii, M. A.; Lebedev, V. A.; Maksimenkov, L. O.; Minashkin, V. M.; Obvintsev, Y. I.; Chketiani, O. G.

    2016-12-01

    Variations in the surface aerosol over the arid steppe zone of Southern Russia have been measured. The parameters of atmospheric aerosol (mass concentration, both dispersed and elemental compositions) and meteorological parameters were measured in Tsimlaynsk raion (Rostov oblast). The chemical composition of aerosol particles in the atmospheric surface layer has been determined, and the coefficients of enrichment of elements with respect to clarkes in the Earth's crust have been calculated. It is shown that, in summer, arid aerosols are transported from both alkaline and sandy soils of Kalmykia to the air basin over the observation zone. Aerosol particles in the surface air layer over this region have been found to contain the products of combustion of oil, coal, and ethylized fuel. These combustion products make a small contribution to the total mass concentration of atmospheric aerosol; however, they are most hazardous to the health of people because of their sizes and heavy-metal contents. A high concentration of submicron sulfur-containing aerosol particles of chemocondensation nature has been recorded. Sources of aerosol of both natural and anthropogenic origins in southern Russia are discussed.

  3. Chemical characterization of submicron aerosol particles during wintertime in a northwest city of China using an Aerodyne aerosol mass spectrometry.

    PubMed

    Zhang, Xinghua; Zhang, Yangmei; Sun, Junying; Yu, Yangchun; Canonaco, Francesco; Prévôt, Andre S H; Li, Gang

    2017-03-01

    An Aerodyne quadrupole aerosol mass spectrometry (Q-AMS) was utilized to measure the size-resolved chemical composition of non-refractory submicron particles (NR-PM1) from October 27 to December 3, 2014 at an urban site in Lanzhou, northwest China. The average NR-PM1 mass concentration was 37.3 μg m(-3) (ranging from 2.9 to 128.2 μg m(-3)) under an AMS collection efficiency of unity and was composed of organics (48.4%), sulfate (17.8%), nitrate (14.6%), ammonium (13.7%), and chloride (5.7%). Positive matrix factorization (PMF) with the multi-linear engine (ME-2) solver identified six organic aerosol (OA) factors, including hydrocarbon-like OA (HOA), coal combustion OA (CCOA), cooking-related OA (COA), biomass burning OA (BBOA) and two oxygenated OA (OOA1 and OOA2), which accounted for 8.5%, 20.2%, 18.6%, 12.4%, 17.8% and 22.5% of the total organics mass on average, respectively. Primary emissions were the major sources of fine particulate matter (PM) and played an important role in causing high chemically resolved PM pollution during wintertime in Lanzhou. Back trajectory analysis indicated that the long-range regional transport air mass from the westerly was the key factor that led to severe submicron aerosol pollution during wintertime in Lanzhou.

  4. Mixing and water-soluble characteristics of particulate organic compounds in individual urban aerosol particles

    NASA Astrophysics Data System (ADS)

    Li, Weijun; Shao, Longyi

    2010-01-01

    Particulate organic compounds (POCs) in the atmosphere can alter the morphology and hygroscopicity of inorganic particles by coagulation and mixing. Direct observations can illustrate the mixing of organic and inorganic particles. Compositions, mixing states, and morphologies of 360 aerosol particles from urban Beijing collected on transmission electron microscopy (TEM) grids with Si-O substrate were obtained using TEM coupled with energy-dispersive X ray spectrometry (TEM/EDX). The Si-O substrate used in this study allows TEM/EDX to detect carbonaceous particles internally mixed with inorganic particles. POCs were present in approximately 90% of the nitrate-coated mineral particles on both hazy and clear days. Approximately 73% of K- and S-rich particles contained organic coatings and organic inclusions/aggregations on hazy days, while 53% of S-rich particles on clear days during the Beijing Olympics contained only organic coatings. Water dialysis of individual particles indicated that the organic inclusions/aggregations in the K- and S-rich particles were insoluble in water but that POCs from the coatings of individual particles were soluble. The organic coatings on individual inorganic particles may influence their surface hygroscopicity and optical properties.

  5. Predicting the mineral composition of dust aerosols - Part 1: Representing key processes

    NASA Astrophysics Data System (ADS)

    Perlwitz, J. P.; Pérez García-Pando, C.; Miller, R. L.

    2015-02-01

    Soil dust aerosols created by wind erosion are typically assigned globally uniform physical and chemical properties within Earth system models, despite known regional variations in the mineral content of the parent soil. Mineral composition of the aerosol particles is important to their interaction with climate, including shortwave absorption and radiative forcing, nucleation of cloud droplets and ice crystals, coating by heterogeneous uptake of sulfates and nitrates, and atmospheric processing of iron into bioavailable forms that increase the productivity of marine phytoplankton. Here, aerosol mineral composition is derived by extending a method that provides the composition of a wet-sieved soil. The extension accounts for measurements showing significant differences between the mineral fractions of the wet-sieved soil and the resulting aerosol concentration. For example, some phyllosilicate aerosols are more prevalent at silt sizes, even though they are nearly absent in a soil whose aggregates are dispersed by wet sieving during analysis. We reconstruct the undispersed size distribution of the original soil that is subject to wind erosion. An empirical constraint upon the relative emission of clay and silt is applied that further differentiates the soil and aerosol mineral composition. In addition, a method is proposed for mixing minerals with small impurities composed of iron oxides. These mixtures are important for transporting iron far from the dust source, because pure iron oxides are more dense and vulnerable to gravitational removal than most minerals comprising dust aerosols. A limited comparison to measurements from North Africa shows that the extension brings the model into better agreement, consistent with a more extensive comparison to global observations as well as measurements of elemental composition downwind of the Sahara, as described in companion articles.

  6. Aerosol Particle Property Comparisons Between MISR and AERONET Retrieved Values

    NASA Astrophysics Data System (ADS)

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

    2005-12-01

    Aerosol optical depth (AOT) data from the Multi-angle ImagingSpectroRadiometer (MISR) instrument aboard the NASA Earth Observing System's Terra satellite have already been systematically compared with ground-based data from the AERONET network. As a result of that study, MISR data are now being reprocessed with improved aerosol algorithms and aerosol models. The follow-on study reported here systematically compares MISR and AERONET particle micro-physical properties. This project is currently underway. Our goal is to use the statistical power of numerous AERONET measurements to map the behavior of the MISR property retrievals, identify strength and surprises in the MISR data, and use this information both to refine further the MISR retrieval algorithms and to assess the likely error envelopes in the MISR products. Multi-year data from 36 carefully chosen sites having good long-term measurement records are stratified by broad classes of aerosol air mass types: maritime, biomass burning, desert dust, pollution, and continental aerosols. Available AERONET spectral AOT measurements for two-hour windows around MISR overpass times are interpolated to MISR wavelengths and averaged, and AOT variability over the two-hour window is noted. Sky-scan AERONET data, taken only once an hour, are also were interpolated to MISR wavelengths, and are averaged over a four-hour window provided the variability is smaller than MISR sensitivity to particle properties based on previous work. MISR retrievals over the 17.6 km standard retrieval regions that include the AERONET sites are preferentially used for the comparison. The MISR measurements are averages of over all "successful" aerosol type models in the MISR algorithm climatology, where success is measured by the degree to which multi-angle, multi-spectral top-of-atmosphere radiances match modeled radiances, using several chi-squared tests. Angstrom exponent, single scattering albedo, and size distribution mean values and variance

  7. Combined effects of organic aerosol loading and fog processing on organic aerosols oxidation and composition

    NASA Astrophysics Data System (ADS)

    Chakraborty, Abhishek; Tripathi, Sachchida; Gupta, Tarun

    2016-04-01

    Fog is a natural meteorological phenomenon that occurs throughout the world, it contains substantial quantity of liquid water and generally seen as a natural cleansing agent but it also has the potential to form highly oxidized secondary organic aerosols (SOA) via aqueous processing of ambient aerosols. On the other hand higher organic aerosols (OA) loading tend to decrease the overall oxidation level (O/C) of the particle phase organics, due to enhanced partitioning of less oxidized organics from gas to particle phase. However, combined impact of these two parameters; aqueous oxidation and OA loading, on the overall oxidation ratio (O/C) of ambient OA has never been studied. To assess this, real time ambient sampling using HR-ToF-AMS was carried out at Kanpur, India from 15 December 2014 - 10 February 2015. In first 3 weeks of this campaign, very high OA loading is (134 ± 42 μg/m3) observed (termed as high loading or HL period) while loading is substantially reduced from 2nd January, 2016 (56 ± 20 μg/m3, termed as low loading or LL period) . However, both the loading period was affected by several fog episodes (10 in HL and 7 in LL), thus providing the opportunity of studying the combined effects of fog and OA loading on OA oxidation. It is found that O/C ratio is very strongly anti-correlated with OA loading in both the loading period, however, slope of this ant-correlation is much steep during HL period than in LL period. Source apportionment of OA revealed that there is drastic change in the types of OA from HL to LL period, clearly indicating difference in OA composition from HL to LL period. During foggy night continuous oxidation of OA is observed from early evening to early morning with 15-20% enhancement in O/C ratio, while the same is absent during non-foggy period, clearly indicating the efficient fog processing of ambient OA. It is also found that night time fog aqueous oxidation can be as effective as daytime photo chemistry in oxidation of OA. Fog

  8. The relation between aerosol particles and lightning in Mexico

    NASA Astrophysics Data System (ADS)

    Kucienska, B.; Cervantes Villa, J. S.; Raga, G. B.

    2013-05-01

    The analysis of lightning activity registered by the World Wide Lightning Location Network and aerosol optical depth (AOD) derived from the Moderate Resolution Imaging Spectroradiometer indicate that spatial and temporal variations in cloud-to-ground lightning density over Mexico are linked to variations in aerosol amounts. Average lightning activity registered on days with moderate AOD is higher than that registered on days with low AOD for most of the continental areas and coastal maritime regions. This finding could be explained either by the aerosol effect on thunderstorms electrical activity or by a similar influence of meteorological conditions on both lightning and AOD. Analysis of temporal variations of electrical activity show that over large continental areas a significant lightning density is observed during spring, at the very beginning of rainy seasons. In May, when rainfall is relatively low, an exceptionally high lightning activity is also registered over the Pacific, in the region located south to Isthmus of Tehuantepec. This signal of high lightning density propagates hundreds of kilometers away from the coast. We hypothesize that high lightning activity during spring observed over both continental and oceanic regions is linked to the presence of aerosol particle generated by biomass burning which peaks in April and May.

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

    NASA Astrophysics Data System (ADS)

    Slowik, Jay G.

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

  10. Understanding hygroscopic growth and phase transformation of aerosols using single particle Raman spectroscopy in an electrodynamic balance.

    PubMed

    Lee, Alex K Y; Ling, T Y; Chan, Chak K

    2008-01-01

    Hygroscopic growth is one of the most fundamental properties of atmospheric aerosols. By absorbing or evaporating water, an aerosol particle changes its size, morphology, phase, chemical composition and reactivity and other parameters such as its refractive index. These changes affect the fate and the environmental impacts of atmospheric aerosols, including global climate change. The ElectroDynamic Balance (EDB) has been widely accepted as a unique tool for measuring hygroscopic properties and for investigating phase transformation of aerosols via single particle levitation. Coupled with Raman spectroscopy, an EDB/Raman system is a powerful tool that can be used to investigate both physical and chemical changes associated with the hygroscopic properties of individually levitated particles under controlled environments. In this paper, we report the use of an EDB/Raman system to investigate (1) contact ion pairs formation in supersaturated magnesium sulfate solutions; (2) phase transformation in ammonium nitrate/ammonium sulfate mixed particles; (3) hygroscopicity of organically coated inorganic aerosols; and (4) heterogeneous reactions altering the hygroscopicity of organic aerosols.

  11. Microphysical aerosol parameters of spheroidal particles via regularized inversion of lidar data

    NASA Astrophysics Data System (ADS)

    Samaras, Stefanos; Böckmann, Christine

    2015-04-01

    One of the main topics in understanding the aerosol impact on climate requires the investigation of the spatial and temporal variability of microphysical properties of particles, e.g., the complex refractive index, the effective radius, the volume and surface-area concentration, and the single-scattering albedo. Remote sensing is a technique used to monitor aerosols in global coverage and fill in the observational gap. This research topic involves using multi-wavelength Raman lidar systems to extract the microphysical properties of aerosol particles, along with depolarization signals to account for the non-sphericity of the latter. Given, the optical parameters (measured by a lidar), the kernel functions, which summarize the size, shape and composition of particles, we solve for the size distribution of the particles modeled by a Fredholm integral system and further calculate the refractive index. This model works well for spherical particles (e.g. smoke); the kernel functions are derived from relatively simplified formulas (Mie scattering theory) and research has led to successful retrievals for particles which at least resemble a spherical geometry (small depolarization ratio). Obviously, more complicated atmospheric structures (e.g dust) require employment of non-spherical kernels and/or more complicated models which are investigated in this paper. The new model is now a two-dimensional one including the aspect ratio of spheroidal particles. The spheroidal kernel functions are able to be calculated via T-Matrix; a technique used for computing electromagnetic scattering by single, homogeneous, arbitrarily shaped particles. In order to speed up the process and massively perform simulation tests, we created a software interface using different regularization methods and parameter choice rules. The following methods have been used: Truncated singular value decomposition and Pade iteration with the discrepancy principle, and Tikhonov regularization with the L

  12. Chemical Imaging of Ambient Aerosol Particles: Observational Constraints on Mixing State Parameterization

    SciTech Connect

    O'Brien, Rachel; Wang, Bingbing; Laskin, Alexander; Riemer, Nicole; West, Matthew; Zhang, Qi; Sun, Yele; Yu, Xiao-Ying; Alpert, Peter A.; Knopf, Daniel A.; Gilles, Mary K.; Moffet, Ryan

    2015-09-28

    A new parameterization for quantifying the mixing state of aerosol populations has been applied for the first time to samples of ambient particles analyzed using spectro-microscopy techniques. Scanning transmission x-ray microscopy/near edge x-ray absorption fine structure (STXM/NEXAFS) and computer controlled scanning electron microscopy/energy dispersive x-ray spectroscopy (CCSEM/EDX) were used to probe the composition of the organic and inorganic fraction of individual particles collected on June 27th and 28th during the 2010 Carbonaceous Aerosols and Radiative Effects (CARES) study in the Central Valley, California. The first field site, T0, was located in downtown Sacramento, while T1 was located near the Sierra Nevada Mountains. Mass estimates of the aerosol particle components were used to calculate mixing state metrics, such as the particle-specific diversity, bulk population diversity, and mixing state index, for each sample. Both microscopy imaging techniques showed more changes over these two days in the mixing state at the T0 site than at the T1 site. The STXM data showed evidence of changes in the mixing state associated with a build-up of organic matter confirmed by collocated measurements and the largest impact on the mixing state was due to an increase in soot dominant particles during this build-up. The CCSEM/EDX analysis showed the presence of two types of particle populations; the first was dominated by aged sea salt particles and had a higher mixing state index (indicating a more homogeneous population), the second was dominated by carbonaceous particles and had a lower mixing state index.

  13. Chemical imaging of ambient aerosol particles: Observational constraints on mixing state parameterization

    DOE PAGES

    O'Brien, Rachel E.; Wang, Bingbing; Laskin, Alexander; ...

    2015-08-26

    In this study, a new parameterization for quantifying the mixing state of aerosol populations has been applied for the first time to samples of ambient particles analyzed using spectro-microscopy techniques. Scanning transmission X-ray microscopy/near edge X-ray absorption fine structure (STXM/NEXAFS) and computer-controlled scanning electron microscopy/energy dispersive X-ray spectroscopy (CCSEM/EDX) were used to probe the composition of the organic and inorganic fraction of individual particles collected on 27 and 28 June during the 2010 Carbonaceous Aerosols and Radiative Effects study in the Central Valley, California. The first field site, T0, was located in downtown Sacramento, while T1 was located near themore » Sierra Nevada Mountains. Mass estimates of the aerosol particle components were used to calculate mixing state metrics, such as the particle-specific diversity, bulk population diversity, and mixing state index, for each sample. The STXM data showed evidence of changes in the mixing state associated with a buildup of organic matter confirmed by collocated measurements, and the largest impact on the mixing state was due to an increase in soot dominant particles during this buildup. The mixing state from STXM was similar between T0 and T1, indicating that the increased organic fraction at T1 had a small effect on the mixing state of the population. The CCSEM/EDX analysis showed the presence of two types of particle populations: the first was dominated by aged sea-salt particles and had a higher mixing state index (indicating a more homogeneous population); the second was dominated by carbonaceous particles and had a lower mixing state index.« less

  14. Chemical imaging of ambient aerosol particles: Observational constraints on mixing state parameterization

    SciTech Connect

    O'Brien, Rachel E.; Wang, Bingbing; Laskin, Alexander; Riemer, Nicole; West, Matthew; Zhang, Qi; Sun, Yele; Yu, Xiao -Ying; Alpert, Peter; Knopf, Daniel A.; Gilles, Mary K.; Moffet, Ryan C.

    2015-08-26

    In this study, a new parameterization for quantifying the mixing state of aerosol populations has been applied for the first time to samples of ambient particles analyzed using spectro-microscopy techniques. Scanning transmission X-ray microscopy/near edge X-ray absorption fine structure (STXM/NEXAFS) and computer-controlled scanning electron microscopy/energy dispersive X-ray spectroscopy (CCSEM/EDX) were used to probe the composition of the organic and inorganic fraction of individual particles collected on 27 and 28 June during the 2010 Carbonaceous Aerosols and Radiative Effects study in the Central Valley, California. The first field site, T0, was located in downtown Sacramento, while T1 was located near the Sierra Nevada Mountains. Mass estimates of the aerosol particle components were used to calculate mixing state metrics, such as the particle-specific diversity, bulk population diversity, and mixing state index, for each sample. The STXM data showed evidence of changes in the mixing state associated with a buildup of organic matter confirmed by collocated measurements, and the largest impact on the mixing state was due to an increase in soot dominant particles during this buildup. The mixing state from STXM was similar between T0 and T1, indicating that the increased organic fraction at T1 had a small effect on the mixing state of the population. The CCSEM/EDX analysis showed the presence of two types of particle populations: the first was dominated by aged sea-salt particles and had a higher mixing state index (indicating a more homogeneous population); the second was dominated by carbonaceous particles and had a lower mixing state index.

  15. Impact of aerosol composition and foliage characteristics on forest canopy deposition rates: A laboratory study

    NASA Astrophysics Data System (ADS)

    Hornsby, K. E.; Pryor, S. C.

    2013-12-01

    Forests are a major sink for atmospheric aerosols. Hence it has been suggested that (i) increased tree planting in urban areas might lead to a reduction in aerosol particle concentrations and thus a reduction in respiratory conditions and heart complications, and (ii) forests may be responsible for removing a disproportionately large fraction of potentially climate-relevant fine and ultra-fine aerosol particles from the atmosphere. However, larger uncertainties remain with respect to controls on uptake rates for forests. E.g. the deposition flux partitioning between foliage and non-foliage elements, the influence of particle size and composition, the role of leaf surface morphology and stomatal aperture in surface uptake. Improved understanding of the relative importance of these factors and the variability across different tree species should help determine how much of a sink naturally occurring and planted forests can provide downstream of fine particle production. In this study, a sample of trees native to southern Indiana were exposed to ultra-fine aerosol particle populations in a 1.5 m x 1.5 m x 1.5 m Teflon chamber. Stable particle size distributions (PSD) with geometric mean diameters (GMD) ranging from 40 to 80 nm were generated from sodium chloride, ammonium nitrate, ammonium sulfate and sodium sulfite solutions using a TSI model 3940 Aerosol Generation System (AGS). The aerosol stream was diluted using scrubbed and dried zero air to allow a variation of total number concentration across two orders of magnitude. PSD in the chamber are continuously measured using a TSI Scanning Mobility Particle Spectrometer (SMPS) comprising an Electrostatic Classifier (EC model 3080) attached to a Long DMA (LDMA model 3081) and a TSI model 3025A Butanol Condensation Particle Counter (CPC) operated with both the internal diffusion loss and multiple charge corrections turned on. The composition of the chamber air was also monitored for carbon dioxide (CO2) and water vapor

  16. 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

  17. 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

  18. Single particle mass spectral signatures from vehicle exhaust particles and the source apportionment of on-line PM2.5 by single particle aerosol mass spectrometry.

    PubMed

    Yang, Jian; Ma, Shexia; Gao, Bo; Li, Xiaoying; Zhang, Yanjun; Cai, Jing; Li, Mei; Yao, Ling'ai; Huang, Bo; Zheng, Mei

    2017-03-24

    In order to accurately apportion the many distinct types of individual particles observed, it is necessary to characterize fingerprints of individual particles emitted directly from known sources. In this study, single particle mass spectral signatures from vehicle exhaust particles in a tunnel were performed. These data were used to evaluate particle signatures in a real-world PM2.5 apportionment study. The dominant chemical type originating from average positive and negative mass spectra for vehicle exhaust particles are EC species. Four distinct particle types describe the majority of particles emitted by vehicle exhaust particles in this tunnel. Each particle class is labeled according to the most significant chemical features in both average positive and negative mass spectral signatures, including ECOC, NaK, Metal and PAHs species. A single particle aerosol mass spectrometry (SPAMS) was also employed during the winter of 2013 in Guangzhou to determine both the size and chemical composition of individual atmospheric particles, with vacuum aerodynamic diameter (dva) in the size range of 0.2-2μm. A total of 487,570 particles were chemically analyzed with positive and negative ion mass spectra and a large set of single particle mass spectra was collected and analyzed in order to identify the speciation. According to the typical tracer ions from different source types and classification by the ART-2a algorithm which uses source fingerprints for apportioning ambient particles, the major sources of single particles were simulated. Coal combustion, vehicle exhaust, and secondary ion were the most abundant particle sources, contributing 28.5%, 17.8%, and 18.2%, respectively. The fraction with vehicle exhaust species particles decreased slightly with particle size in the condensation mode particles.

  19. Aerosol mass spectrometry: particle-vaporizer interactions and their consequences for the measurements

    NASA Astrophysics Data System (ADS)

    Drewnick, F.; Diesch, J.-M.; Faber, P.; Borrmann, S.

    2015-09-01

    The Aerodyne aerosol mass spectrometer (AMS) is a frequently used instrument for on-line measurement of the ambient sub-micron aerosol composition. With the help of calibrations and a number of assumptions on the flash vaporization and electron impact ionization processes, this instrument provides robust quantitative information on various non-refractory ambient aerosol components. However, when measuring close to certain anthropogenic or marine sources of semi-refractory aerosols, several of these assumptions may not be met and measurement results might easily be incorrectly interpreted if not carefully analyzed for unique ions, isotope patterns, and potential slow vaporization associated with semi-refractory species. Here we discuss various aspects of the interaction of aerosol particles with the AMS tungsten vaporizer and the consequences for the measurement results: semi-refractory components - i.e., components that vaporize but do not flash-vaporize at the vaporizer and ionizer temperatures, like metal halides (e.g., chlorides, bromides or iodides of Al, Ba, Cd, Cu, Fe, Hg, K, Na, Pb, Sr, Zn) - can be measured semi-quantitatively despite their relatively slow vaporization from the vaporizer. Even though non-refractory components (e.g., NH4NO3 or (NH4)2SO4) vaporize quickly, under certain conditions their differences in vaporization kinetics can result in undesired biases in ion collection efficiency in thresholded measurements. Chemical reactions with oxygen from the aerosol flow can have an influence on the mass spectra for certain components (e.g., organic species). Finally, chemical reactions of the aerosol with the vaporizer surface can result in additional signals in the mass spectra (e.g., WO2Cl2-related signals from particulate Cl) and in conditioning or contamination of the vaporizer, with potential memory effects influencing the mass spectra of subsequent measurements. Laboratory experiments that investigate these particle-vaporizer interactions are

  20. Scanning Transmission X-ray microscopy Imaging of Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Gilles, M. K.; Kilcoyne, A.; Tyliszczak, T.; Shuh, D. K.; Fakra, S.; Robinson, M.; Chase, K.

    2003-12-01

    Scanning transmission x-ray microscopes (STXM) are used to image a diversity of carbon and metal containing items such as biofilms in soils, magnetic materials, polymers and meteorites. Studies on particles collected on SiO2 filters from biomass burns in Flagstaff, Arizona and individual aerosols collected in South Africa on TEM grids are underway at beamlines 5.3.2 and 11.0.2 at the Advanced Light Source of Lawrence Berkeley National Laboratory. Sub micron particles are imaged in the transmission mode over the energy range of 280 - 1900 eV. Spectromicroscopic studies on individual particles using near edge x-ray absorption fine structure (NEXAFS) probe multiple species within or on the same particle. In (STXM) an X-ray beam is focused with a zone plate onto a sample and the transmitted radiation is detected. Since the signal is obtained in the transmission mode, optically thin samples are required. Hence, atmospheric aerosols with submicron thickness and diameter are well suited for this method. Near edge spectra of various elements were scanned in step sizes from 0.1-0.5 eV around characteristic absorption edges, creating 2 dimensional images at each energy. While STXM images are taken with a lower spatial resolution (currently 40 nm) than microscopies such as scanning electron microscopy, transmission electron microscopy, and atomic force microscopy, detailed chemical information with spatial distributions, and oxidation states is obtained. A particular focus of this work is to obtain more detailed information on the type of carbons, multiply, or singly bonded and whether or not carbon is bonded to oxygen. The ultimate goal is discrimination between organic and black carbon within individual aerosol particles and determining if organic carbon, black carbon, and metal species are distributed homogeneously throughout aerosol particles. Initial scans of the samples from Flagstaff show spectral evidence of aromatic carbon, without distinct C=O signatures. NEXAFS

  1. Characterization of Individual Aerosol Particles Associated with Clouds (CRYSTAL-FACE)

    NASA Technical Reports Server (NTRS)

    Buseck, Peter R.

    2004-01-01

    The aim of our research was to obtain data on the chemical and physical properties of individual aerosol particles from near the bottoms and tops of the deep convective systems that lead to the generation of tropical cirrus clouds and to provide insights into the particles that serve as CCN or IN. We used analytical transmission electron microscopy (ATEM), including energy-dispersive X-ray spectrometry (EDS) and electron energy-loss spectroscopy (EELS), and field-emission electron microscopy (FESEM) to compare the compositions, concentrations, size distributions, shapes, surface coatings, and degrees of aggregation of individual particles from cloud bases and the anvils near the tropopause. Aggregates of sea salt and mineral dust, ammonium sulfate, and soot particles are abundant in in-cloud samples. Cirrus samples contain many H2SO4 droplets, but acidic sulfate particles are rare at the cloud bases. H2SO4 probably formed at higher altitudes through oxidation of SO2 in cloud droplets. The relatively high extent of ammoniation in the upper troposphere in-cloud samples appears to have resulted from vertical transport by strong convection. The morphology of H2SO4 droplets indicates that they had been at least yartiy ammoniated at the time of collection. They are internally mixed with organic materials, metal sulfates, and solid particles of various compositions. Ammoniation and internal mixing of result in freezing at higher temperature than in pure H2SO4 aerosols. K- and S-bearing organic particles and Si-Al-rich particles are common throughout. Sea salt and mineral dust were incorporated into the convective systems from the cloud bases and worked as ice nuclei while being vertically transported. The nonsulfate particles originated from the lower troposphere and were transported to the upper troposphere and lower stratosphere.

  2. Physicochemical characterization of Capstone depleted uranium aerosols I: uranium concentration in aerosols as a function of time and particle size.

    PubMed

    Parkhurst, Mary Ann; Cheng, Yung Sung; Kenoyer, Judson L; Traub, Richard J

    2009-03-01

    During the Capstone Depleted Uranium (DU) Aerosol Study, aerosols containing DU were produced inside unventilated armored vehicles (i.e., Abrams tanks and Bradley Fighting Vehicles) by perforation with large-caliber DU penetrators. These aerosols were collected and characterized, and the data were subsequently used to assess human health risks to personnel exposed to DU aerosols. The DU content of each aerosol sample was first quantified by radioanalytical methods, and selected samples, primarily those from the cyclone separator grit chambers, were analyzed radiochemically. Deposition occurred inside the vehicles as particles settled on interior surfaces. Settling rates of uranium from the aerosols were evaluated using filter cassette samples that collected aerosol as total mass over eight sequential time intervals. A moving filter was used to collect aerosol samples over time, particularly within the first minute after a shot. The results demonstrate that the peak uranium concentration in the aerosol occurred in the first 10 s after perforation, and the concentration decreased in the Abrams tank shots to about 50% within 1 min and to less than 2% after 30 min. The initial and maximum uranium concentrations were lower in the Bradley vehicle than those observed in the Abrams tank, and the concentration levels decreased more slowly. Uranium mass concentrations in the aerosols as a function of particle size were evaluated using samples collected in a cyclone sampler, which collected aerosol continuously for 2 h after perforation. The percentages of uranium mass in the cyclone separator stages ranged from 38 to 72% for the Abrams tank with conventional armor. In most cases, it varied with particle size, typically with less uranium associated with the smaller particle sizes. Neither the Abrams tank with DU armor nor the Bradley vehicle results were specifically correlated with particle size and can best be represented by their average uranium mass concentrations of 65

  3. Chemical boundary conditions for the classification of aerosol particles using computer controlled electron probe microanalysis.

    PubMed

    Anaf, Willemien; Horemans, Benjamin; Van Grieken, René; De Wael, Karolien

    2012-11-15

    A method for the classification of individual aerosol particles using computer controlled electron probe microanalysis is presented. It is based on chemical boundary conditions (CBC) and enables quick and easy processing of a large set of elemental concentration data (mass%), derived from the X-ray spectra of individual particles. The particles are first classified into five major classes (sea salt related, secondary inorganic, minerals, iron-rich and carbonaceous), after which advanced data mining can be performed by examining the elemental composition of particles within each class into more detail (e.g., by ternary diagrams). The CBC method is validated and evaluated by comparing its results with the output obtained with hierarchical cluster analysis (HCA) for well-known standard particles as well as real aerosol particles collected with a cascade impactor. The CBC method gives reliable results and has a major advantage compared to HCA. CBC is based on boundary conditions that are derived from chemical logical thinking and does not require a translation of a mathematical algorithm output as does HCA. Therefore, the CBC method is more objective and enables comparison between samples without intermediate steps.

  4. Physicochemical Characterization of Coarse Lake Spray Aerosol Particle from Lake Michigan

    NASA Astrophysics Data System (ADS)

    Ault, A. P.; Axson, J. L.; May, N.; Pratt, K.; Colon-Bernal, I. D.

    2015-12-01

    Wave breaking across bodies of water releases coarse particles into the air which can impact climate and human health. Freshwater lakes, such as the Great Lakes, can generate lake spray aerosols (LSA), similarly to how sea spray is generated, during periods of high winds and wave action. This LSA has the potential to impact climate through direct and indirect effects (ie. scattering/absorption and cloud nucleation) and are suggested to impact human health via inhalation of these particles during algal bloom periods characterized by toxic cyanobacteria. Very few studies have been conducted to assess the physicochemical properties of freshwater LSA. Prior work in our lab included the construction and characterization of a laboratory based LSA generator. In this work, we examine laboratory generated aerosol particles from laboratory based freshwater standards, freshwater samples collected from Lake Michigan, and ambient particles collected during a wave event on the shores of Lake Michigan in the summer of 2015. Particle size distributions, number concentrations, and chemical composition are presented and discussed as a function of laboratory generated and ambient collected LSA. Results indicate that there are characteristic particles that represent LSA. This study represents the next step towards evaluating and understanding the potential for coarse LSA to impact climate and health in the Great Lakes region.

  5. Dust in the Sky: Atmospheric Composition. Modeling of Aerosol Optical Thickness

    NASA Technical Reports Server (NTRS)

    Chin, Mian; Ginoux, Paul; Kinne, Stefan; Torres, Omar; Holben, Brent; Duncan, Bryan; Martin, Randall; Logan, Jennifer; Higurashi, Akiko; Nakajima, Teruyuki

    2000-01-01

    Aerosol is any small particle of matter that rests suspended in the atmosphere. Natural sources, such as deserts, create some aerosols; consumption of fossil fuels and industrial activity create other aerosols. All the microscopic aerosol particles add up to a large amount of material floating in the atmosphere. You can see the particles in the haze that floats over polluted cities. Beyond this visible effect, aerosols can actually lower temperatures. They do this by blocking, or scattering, a portion of the sun's energy from reaching the surface. Because of this influence, scientists study the physical properties of atmospheric aerosols. Reliable numerical models for atmospheric aerosols play an important role in research.

  6. 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.

  7. Using microchip electrophoresis for real-time aerosol composition measurements: Field study results from San Gorgonio Wilderness, California

    NASA Astrophysics Data System (ADS)

    Evanoski-Cole, A. R.; Hecobian, A.; Lewis, G. S.; Hering, S. V.; Henry, C. S.; Collett, J. L.

    2012-12-01

    The detrimental impacts of atmospheric aerosol on human and ecosystem health, visibility and climate change have been studied extensively. However, the role of aerosol composition in these issues still needs further investigation due to the variability of aerosol particles over both time and space. The need for better temporal and spatial resolution of aerosol composition measurements is addressed in the development of a real-time instrument using microchip capillary electrophoresis. Termed Aerosol microChip Electrophoresis (ACE), this lab-on-a-chip instrument is inexpensive to manufacture, portable and provides sensitive real-time and semi-continuous aerosol composition measurements. A water condensation growth tube is used to enlarge water soluble aerosol particles with an aerodynamic diameter less than 2.5 μm. The aqueous sample is continuously collected by impaction into a sample reservoir on a custom designed microchip. A rapid separation of select aerosol components is achieved using microchip capillary electrophoresis coupled with conductivity detection. Here we present data from a recent field campaign in the San Gorgonio Wilderness in south western California. This unique high elevation wilderness site located to the east of the heavily populated cities of San Bernardino and Los Angeles provides a contrast of both clean background and aged urban aerosol as dictated by the meteorological conditions at the site. Ambient aerosol particles were continuously collected at a flow rate of 0.7 L/min into a liquid sample with a volume of 16.7 μL and then analyzed for sulfate, nitrate, chloride and oxalate every 48 seconds. When comparing the ambient concentrations with the meteorological conditions, the most notable trend was high nitrate and sulfate concentrations in ambient aerosol during upslope wind events, with values reaching as high as 34 and 5 μg/m3, respectively. Comparison aerosol composition measurements from filter samples and a particle

  8. Relationship between aerosol oxidation level and hygroscopic properties of laboratory generated secondary organic aerosol (SOA) particles

    NASA Astrophysics Data System (ADS)

    Massoli, P.; Lambe, A.; Ahern, A.; Williams, L. R.; Ehn, M.; Mikkila, J.; Canagaratna, M.; Brune, W. H.; Onasch, T. B.; Jayne, J.; Petdjd, T. T.; Kulmala, M. T.; Laaksonen, A.; Kolb, C. E.; Davidovits, P.; Worsnop, D. R.

    2010-12-01

    Laboratory experiments investigated the relationship between degree of oxidation and hygroscopic properties of secondary organic aerosol (SOA) particles. The hygroscopic growth factor (HGF), the CCN activity (κCCN) and the degree of aerosol oxidation (represented by the atomic O:C ratio) were measured for α-pinene, 1,3,5-trimethylbenzene (TMB), m-xylene and α pinene/m-xylene mixture SOA generated via OH radical oxidation in an aerosol flow reactor. Our results show that both HGF and κCCN increase with O:C. The TMB and m-xylene SOA were, respectively, the least and most hygroscopic of the system studied. An average HGF of 1.25 and a κCCN of 0.2 were measured at O:C of 0.65, in agreement with results reported for ambient data. The HGF based κ(κHGF) under predicted the κCCN values of 20 to 50% for all but the TMB SOA. Within the limitations of instrumental capabilities, we define the extent to which the hygroscopic properties of SOA particles can be predicted from their oxidation level and provide parameterizations suitable for interpreting ambient data.

  9. 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...

  10. 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.

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

    PubMed Central

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

    2012-01-01

    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

  12. 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.

  13. Chemical Analysis of Individual Aerosols Particles by Electron Energy-Loss Spectroscopy (EELS)

    NASA Astrophysics Data System (ADS)

    Buseck, P. R.; Buseck, P. R.; Garvie, L. A.; Li, J.; Posfai, M.

    2001-12-01

    We use electron energy-loss spectroscopy (EELS) with a transmission electron microscope (TEM) to obtain chemical and bonding information on individual aerosol particles. EELS is ideally suited to this task because of its high spatial resolution and sensitivity to light elements such as C, N, and O. In addition, the spectral shapes provide information regarding bonding, atomic coordination and, for polyvalent elements, oxidation states. Our current focus is on carbonaceous aerosols both in the ambient air and emissions from biomass burning, with emphasis on the heterogeneous chemistry, particle structure, and chemical composition of soot particles. From the EELS spectra we were able to record for the first time, differences in composition between individual spherules within the same soot aggregate. We also found evidence of chemical variations even within individual soot spheres as small as 50 nm across. In the case of biomass burning, the most striking chemical differences are in the quantity of K, minor O and, in places, N. The quantity of elements associated with C decreases with the degree of graphitization of the soot spheres, as shown by the shapes of the C spectra and was corroborated by high-resolution TEM images of the analyzed particles. Knowledge of the degree of graphitization and quantity of associated elements is important for understanding and modeling their optical properties and in some case in source attributions.

  14. The Influence of Aerosol Composition on Photolysis Rates Based on Airborne Observations

    NASA Astrophysics Data System (ADS)

    Corr, C.; Barrick, J. D. W.; Beyersdorf, A. J.; Chen, G.; Crawford, J. H.; Jordan, C. E.; Moore, R.; Shook, M.; Thornhill, K. L., II; Winstead, E.; Ziemba, L. D.; Madronich, S.; Anderson, B. E.

    2015-12-01

    The potential variability in modeled photolysis rates introduced by aerosol optical properties measured at visible wavelengths is presented here. Aerosol scattering and absorption were measured aboard the NASA P-3B aircraft during the Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) using a TSI Nephelometer and a Radiance Research Particle Soot Absorption Photometer (PSAP), respectively. To isolate the effect of aerosols on photolysis rates, cloud-free case studies were identified using aircraft videos for the four DISCOVER-AQ deployments: Baltimore, MD-Washington, D.C. in July 2011, the California Central Valley in January/February 2013, Houston, TX in September 2013, and Denver, CO in July 2014. For these case studies, absorption measurements at 470 and 532 nm were extrapolated to the Nephelometer wavelengths (450 and 550nm) using the 470-532nm absorption Angstrom exponent (AAE470-532) to calculate aerosol extinction and SSAs at these wavelengths. Photolysis rates were modeled using the Tropospheric Ultraviolet model version 5.2 (TUV 5.2) for three scenarios: 1) an aerosol-free case, 2) using a spectrally-flat SSA at 550nm and 3) using a spectrally-dependent SSA derived from scattering and absorption measurements. Modeled photolysis rates were compared to those measured aboard the P-3B during DISCOVER-AQ. The relationship between airborne measurements of water soluble organic carbon (WSOC) made by a Particle-Into-Liquid-Sampler (PILS), AAE470-532 and model/measurement discrepancies were explored to assess the influence of aerosol composition on photolysis rates. Additional comparisons between photolysis rates modeled with vertically-resolved aerosol optical properties and those modeled using column-average values were performed to assess the influence of aerosol vertical distribution on photolysis rates.

  15. Airborne studies of aerosol emissions from savanna fires in southern Africa: 2. Aerosol chemical composition

    NASA Astrophysics Data System (ADS)

    Andreae, M. O.; Andreae, T. W.; Annegarn, H.; Beer, J.; Cachier, H.; Le Canut, P.; Elbert, W.; Maenhaut, W.; Salma, I.; Wienhold, F. G.; Zenker, T.

    1998-12-01

    We investigated smoke emissions from fires in savanna, forest, and agricultural ecosystems by airborne sampling of plumes close to prescribed burns and incidental fires in southern Africa. Aerosol samples were collected on glass fiber filters and on stacked filter units, consisting of a Nuclepore prefilter for particles larger than ˜1-2 μm and a Teflon second filter stage for the submicron fraction. The samples were analyzed for soluble ionic components, organic carbon, and black carbon. Onboard the research aircraft, particle number and volume distributions as a function of size were determined with a laser-optical particle counter and the black carbon content of the aerosol with an aethalometer. We determined the emission ratios (relative to CO2 and CO) and emission factors (relative to the amount of biomass burnt) for the various aerosol constituents. The smoke aerosols were rich in organic and black carbon, the latter representing 10-30% of the aerosol mass. K+ and NH4+ were the dominant cationic species in the smoke of most fires, while Cl- and SO42- were the most important anions. The aerosols were unusually rich in Cl-, probably due to the high Cl content of the semiarid vegetation. Comparison of the element budget of the fuel before and after the fires shows that the fraction of the elements released during combustion is highly variable between elements. In the case of the halogen elements, almost the entire amount released during the fire is present in the aerosol phase, while in the case of C, N, and S, only a small proportion ends up as particulate matter. This suggests that the latter elements are present predominantly as gaseous species in the fresh fire plumes studied here.

  16. Exploration of the seasonal variation of organic aerosol composition using an explicit modeling approach

    NASA Astrophysics Data System (ADS)

    Ouzebidour, Farida; Camredon, Marie; Stéphanie La, Yuyi; Madronich, Sasha; Taylor, Julia Lee; Hodzic, Alma; Beekmann, Matthias; Siour, Guillaume; Aumont, Bernard

    2014-05-01

    Organic compounds account for a major fraction of fine aerosols in the atmosphere. This organic fraction is dominated by secondary organic aerosol (SOA). Processes leading to SOA formation are however still uncertain and SOA composition is far from being fully characterized. The goals of this study are to evaluate our current understanding of SOA formation and explore its composition. For this purpose, a box-model that describes explicitly processes involved in SOA formation has been developed. This model includes the emission of 183 gaseous and particulate organic compounds. The oxidation of these emitted organic compounds is described using the Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A). Gas/particle partitioning has been implemented considering an ideal homogeneous condensed phase. The generated chemical scheme contains 500,000 species and the gas/particle partitioning is performed for 90,000 of them. Simulations have been performed for summer and winter scenarios representative of continental and urban conditions. NOx and ozone simulated concentrations reproduce the expected winter and summer diurnal evolutions. The predicted organic aerosol composition is a mixture of primary and secondary organic aerosols during the winter and is largely dominated by SOA during the summer.

  17. Chemical Composition and Size Distributions of Coastal Aerosols Observed on the U.S. East Coast

    NASA Astrophysics Data System (ADS)

    Xia, L.; Song, F.; Jusino-Atresino, R.; Thuman, C.; Gao, Y.

    2008-12-01

    Aerosol input is an important source of certain limiting nutrients, such as iron, for phytoplankton growth in several large oceanic regions. As the efficiency of biological uptake of nutrients may depend on the aerosol properties, a better knowledge of aerosol properties is critically important. Characterizing aerosols over the coastal ocean needs special attention, because the properties of aerosols could be altered by many anthropogenic processes in this land-ocean transition zone before they are transported over the remote ocean. The goal of this experiment was to examine aerosol properties, in particular chemical composition, particle-size distributions and iron solubility, over the US Eastern Seaboard, an important boundary for the transport of continental substances from North America to the North Atlantic Ocean. Our field sampling site was located at Tuckerton (39°N, 74°W) on the southern New Jersey coast. Fourteen sets of High-Volume aerosol samples and three sets of size segregated aerosol samples by a 10-stage MOUDI impactor were collected during 2007 and 2008. The ICP-MS methodology was used to analyze aerosol samples for the concentrations of thirteen trace elements: Al, Fe, Mn, Sc, Cd, Pb, Sb, Ni, Co, Cr, Cu, Zn and V. The IC procedures were applied to determine five cations (sodium, ammonium, potassium, magnesium and calcium) and eleven anions (fluoride, acetate, propionate, formate, MSA, chloride, nitrate, succinate, malonate, sulfate and oxalate). The UV spectrometry was employed for the determination of iron solubility. Preliminary results suggest three major sources of aerosols: anthropogenic, crustal and marine. At this location, the concentrations of iron (II) ranged from 2.8 to 29ng m-3, accounting for ~20% of the total iron. The iron concentrations at this coastal site were substantially lower than those observed in Newark, an urban site in northern NJ. High concentrations of iron (II) were associated with both fine and coarse aerosol

  18. The mixing state of carbonaceous aerosol particles in northern and southern California measured during CARES and CalNex 2010

    SciTech Connect

    Cahill, John F.; Suski, Kaitlyn; Seinfeld, John H.; Zaveri, Rahul A.; Prather, Kimberly A.

    2012-11-21

    Carbonaceous aerosols impact climate directly by scattering and absorbing radiation, and hence play a major, although highly uncertain, role in global radiative forcing. Commonly, ambient carbonaceous aerosols are internally mixed with secondary species such as nitrate, sulfate, and ammonium, which influence their climate impacts through optical properties, hygroscopicity, and atmospheric lifetime. Aircraft-aerosol time-of-flight mass spectrometry (A-ATOFMS), which measures single-particle mixing state, was used to determine the fraction of organic and soot aerosols that were internally mixed and the variability of their mixing state in California during the Carbonaceous Aerosol and Radiative Effects Study (CARES) and the Research at the Nexus of Air Quality and Climate Change (CalNex) field campaigns in the late spring and early summer of 2010. Nearly 88% of all A-ATOFMS measured particles (100-1000 nm in diameter) were internally mixed with secondary species, with 96% and 75% of particles internally mixed with nitrate and/or sulfate in southern and northern California, respectively. Even though atmospheric particle composition in both regions was primarily influenced by urban sources, the mixing state was found to vary greatly, with nitrate and soot being the dominant species in southern California, and sulfate and organic carbon in northern California. Furthermore, mixing state varied temporally in northern California, with soot becoming the prevalent particle type towards the end of the study as regional pollution levels increased. The results from these studies demonstrate that the majority of ambient carbonaceous particles are internally mixed and are heavily influenced by secondary species that are most predominant in each region. Based on these findings, considerations of regionally dominant sources and secondary species, as well as temporal variations of aerosol physical and optical properties, will be required to obtain more accurate predictions of the

  19. The mixing state of carbonaceous aerosol particles in northern and southern California measured during CARES and CalNex 2010

    NASA Astrophysics Data System (ADS)

    Cahill, J. F.; Suski, K.; Seinfeld, J. H.; Zaveri, R. A.; Prather, K. A.

    2012-11-01

    Carbonaceous aerosols impact climate directly by scattering and absorbing radiation, and hence play a major, although highly uncertain, role in global radiative forcing. Commonly, ambient carbonaceous aerosols are internally mixed with secondary species such as nitrate, sulfate, and ammonium, which influences their optical properties, hygroscopicity, and atmospheric lifetime, thus impacting climate forcing. Aircraft-aerosol time-of-flight mass spectrometry (A-ATOFMS), which measures single-particle mixing state, was used to determine the fraction of organic and soot aerosols that are internally mixed and the variability of their mixing state in California during the Carbonaceous Aerosols and Radiative Effects Study (CARES) and the Research at the Nexus of Air Quality and Climate Change (CalNex) field campaigns in the late spring and early summer of 2010. Nearly 88% of all A-ATOFMS measured particles (100-1000 nm in diameter) were internally mixed with secondary species, with 96% and 75% of particles internally mixed with nitrate and/or sulfate in southern and northern California, respectively. Even though atmospheric particle composition in both regions was primarily influenced by urban sources, the mixing state was found to vary greatly, with nitrate and soot being the dominant species in southern California, and sulfate and organic carbon in northern California. Furthermore, mixing state varied temporally in northern California, with soot becoming the prevalent particle type towards the end of the study as regional pollution levels increased. The results from these studies demonstrate that the majority of ambient carbonaceous particles in California are internally mixed and are heavily influenced by secondary species that are most prevalent in the particular region. Based on these findings, considerations of regionally dominant sources and secondary species, as well as temporal variations of aerosol physical and optical properties, will be required to obtain more

  20. The mixing state of carbonaceous aerosol particles in Northern and Southern California measured during CARES and CalNex 2010

    NASA Astrophysics Data System (ADS)

    Cahill, J. F.; Suski, K.; Seinfeld, J. H.; Zaveri, R. A.; Prather, K. A.

    2012-07-01

    Carbonaceous aerosols impact climate directly by scattering and absorbing radiation, and hence play a major, although highly uncertain, role in global radiative forcing. Commonly, ambient carbonaceous aerosols are internally mixed with secondary species such as nitrate, sulfate, and ammonium, which influences their optical properties, hygroscopicity, and atmospheric lifetime, thus impacting climate forcing. Aircraft-aerosol time-of-flight mass spectrometry (A-ATOFMS), which measures single-particle mixing state, was used to determine the fraction of organic and soot aerosols that are internally mixed and the variability of their mixing state in California during the Carbonaceous Aerosols and Radiative Effects Study (CARES) and the Research at the Nexus of Air Quality and Climate Change (CalNex) field campaigns in the late spring and early summer of 2010. Nearly 88% of all A-ATOFMS measured particles (100-1000 nm in diameter) were internally mixed with secondary species, with 96% and 75% of particles internally mixed with nitrate and/or sulfate in Southern and Northern California, respectively. Even though atmospheric particle composition in both regions was primarily influenced by urban sources, the mixing state was found to vary greatly, with nitrate and soot being the dominant species in Southern California, and sulfate and organic carbon in Northern California. Furthermore, mixing state varied temporally in Northern California, with soot becoming the prevalent particle type towards the end of the study as regional pollution levels increased. The results from these studies demonstrate that the majority of ambient carbonaceous particles in California are internally mixed and are heavily influenced by secondary species that are most prevalent in the particular region. Based on these findings, considerations of regionally dominant sources and secondary species, as well as temporal variations of aerosol physical and optical properties, will be required to obtain more

  1. Comparison of the DiSCmini aerosol monitor to a handheld condensation particle counter and a scanning mobility particle sizer for submicrometer sodium chloride and metal aerosols.

    PubMed

    Mills, Jessica B; Park, Jae Hong; Peters, Thomas M

    2013-01-01

    We evaluated the robust, lightweight DiSCmini (DM) aerosol monitor for its ability to measure the concentration and mean diameter of submicrometer aerosols. Tests were conducted with monodispersed and polydispersed aerosols composed of two particle types (sodium chloride [NaCl] and spark-generated metal particles, which simulate particles found in welding fume) at three different steady-state concentration ranges (Low, <10(3); Medium, 10(3)-10(4); and High, >10(4) particles/cm(3)). Particle number concentration, lung deposited surface area (LDSA) concentration, and mean size measured with the DM were compared with those measured with reference instruments, a scanning mobility particle sizer (SMPS), and a handheld condensation particle counter (CPC). Particle number concentrations measured with the DM were within 16% of those measured by the CPC for polydispersed aerosols. Poorer agreement was observed for monodispersed aerosols (±35% for most tests and +101% for 300-nm NaCl). LDSA concentrations measured by the DM were 96% to 155% of those estimated with the SMPS. The geometric mean diameters measured with the DM were within 30% of those measured with the SMPS for monodispersed aerosols and within 25% for polydispersed aerosols (except for the case when the aerosol contained a substantial number of particles larger than 300 nm). The accuracy of the DM is reasonable for particles smaller than 300 nm, but caution should be exercised when particles larger than 300 nm are present. [Supplementary materials are available for this article. Go to the publisher's online edition of the Journal of Occupational and Environmental Hygiene for the following free supplemental resources: manufacturer-reported capabilities of instruments used, and information from the SMPS measurements for polydispersed test particles.].

  2. Impacts of aerosol particles on the microphysical and radiative properties of stratocumulus clouds over the southeast Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Twohy, C. H.; Anderson, J. R.; Toohey, D. W.; Andrejczuk, M.; Adams, A.; Lytle, M.; George, R. C.; Wood, R.; Saide, P.; Spak, S.; Zuidema, P.; Leon, D.

    2013-03-01

    there. Thus, larger scale forcings that impact cloud macrophysical properties, as well as enhanced aerosol particles, are important in determining cloud droplet size and cloud albedo. Differences in the size distribution of droplet residual particles and ambient aerosol particles were observed. By progressively excluding small droplets from the CVI sample, we were able to show that the larger drops, some of which may initiate drizzle, contain the largest aerosol particles. Geometric mean diameters of droplet residual particles were larger than those of the below-cloud and above cloud distributions. However, a wide range of particle sizes can act as droplet nuclei in these stratocumulus clouds. A detailed LES microphysical model was used to show that this can occur without invoking differences in chemical composition of cloud-nucleating particles.

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

    PubMed

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

    2011-07-05

    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. Aerosol Chemistry Resolved by Mass Spectrometry: Linking Field Measurements of Cloud Condensation Nuclei Activity to Organic Aerosol Composition.

    PubMed

    Vogel, Alexander L; Schneider, Johannes; Müller-Tautges, Christina; Phillips, Gavin J; Pöhlker, Mira L; Rose, Diana; Zuth, Christoph; Makkonen, Ulla; Hakola, Hannele; Crowley, John N; Andreae, Meinrat O; Pöschl, Ulrich; Hoffmann, Thorsten

    2016-10-06

    Aerosol hygroscopic properties were linked to its chemical composition by using complementary online mass spectrometric techniques in a comprehensive chemical characterization study at a rural mountaintop station in central Germany in August 2012. In particular, atmospheric pressure chemical ionization mass spectrometry ((-)APCI-MS) provided measurements of organic acids, organosulfates, and nitrooxy-organosulfates in the particle phase at 1 min time resolution. Offline analysis of filter samples enabled us to determine the molecular composition of signals appearing in the online (-)APCI-MS spectra. Aerosol mass spectrometry (AMS) provided quantitative measurements of total submicrometer organics, nitrate, sulfate, and ammonium. Inorganic sulfate measurements were achieved by semionline ion chromatography and were compared to the AMS total sulfate mass. We found that up to 40% of the total sulfate mass fraction can be covalently bonded to organic molecules. This finding is supported by both on- and offline soft ionization techniques, which confirmed the presence of several organosulfates and nitrooxy-organosulfates in the particle phase. The chemical composition analysis was compared to hygroscopicity measurements derived from a cloud condensation nuclei counter. We observed that the hygroscopicity parameter (κ) that is derived from organic mass fractions determined by AMS measurements may overestimate the observed κ up to 0.2 if a high fraction of sulfate is bonded to organic molecules and little photochemical aging is exhibited.

  5. Chemical Composition of Atmospheric Aerosols Above a Pristine South East Asian Rainforest

    NASA Astrophysics Data System (ADS)

    Robinson, N. H.; Allan, J. D.; Williams, P. I.; Coe, H.; Hamilton, J.; Chen, Q.; Martin, S.; Trembath, J.

    2009-04-01

    The tropics emit a huge amount of volatile organic compounds (VOCs) into the Earth's atmosphere. The processes by which these gases are oxidised to form secondary organic aerosol (SOA) are currently not well understood or quantified. Intensive field measurements were carried out as part of the Oxidant and Particle Photochemical Processes (OP3) and the Aerosol Coupling in the Earth System (ACES) projects around pristine rainforest in Malaysian Borneo. This is the first campaign of its type in a South East Asian rainforest. We present detailed organic aerosol composition measurements made using an Aerodyne High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS) at Bukit Atur, a Global Atmosphere Watch site located in the Danum Valley Conservation Area. This is a state-of-the-art field deployable instrument that can provide real time composition, mass loading and aerodynamic particle sizing information. In addition, the mass spectral resolution is sufficient to perform an analysis of the elemental composition of the organic species present. Other tools such as positive matrix factorisation (PMF) have been used to help assess the relative source contributions to the organic aerosol. A suite of supporting aerosol and gas phase measurements were made, including size resolved number concentration measurements with Differential Mobility Particle Sizer (DMPS), as well as absorption measurements made with a Multi-Angle Absorption Photometer (MAAP). The ground site data are compared with Aerodyne Compact Time of Flight Aerosol Mass Spectrometer (C-ToF-AMS) measurements made on the UK Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 research aircraft. Airborne measurements were made above pristine rainforest surrounding the Danum Valley site, as well as nearby oil palm agricultural sites and palm oil rendering plants. Airborne hygroscopicity was measured using a Droplet Measurement Technology Cloud Condensation Nuclei counter (DMT CCN counter) in

  6. Aerosol Composition, Chemistry, and Source Characterization during the 2008 VOCALS Experiment

    NASA Astrophysics Data System (ADS)

    Lee, Y.; Springston, S.; Jayne, J. T.; Wang, J.; Senum, G.; Hubbe, J.; Alexander, L.; Brioude, J.; Spak, S.; Mena-Carrasco, M.; Kleinman, L. I.; Daum, P. H.

    2009-12-01

    Chemical composition of fine aerosol particles over the northern Chilean coastal waters was determined on board the US DOE G-1 aircraft during the VOCALS (VAMOS Ocean-Cloud-Atmosphere-Land Study) field experiment between October 16 and November 15, 2008. Chemical species determined included SO42-, NO3-, NH4+, and total organics (Org) using an Aerodyne Aerosol Mass Spectrometer, and SO42-, NO3-, NH4+, Na+, Cl-, CH3SO3-, Mg2+, Ca2+, and K+ using a particle-into-liquid sampler-ion chromatography technique. The results show the marine boundary layer (MBL) aerosol mass was dominated by non-sea-salt SO42- followed by Na+, Cl-, Org, NO3-, and NH4+, in decreasing importance; CH3SO3-, Ca2+, and K+ rarely exceeded their respective limits of detection. The SO42- aerosols were strongly acidic as the equivalent NH4+ to SO42- ratio was only ~0.25 on average. NaCl particles, presumably of sea-salt origin, showed chloride deficits but retained Cl- typically more than half the equivalency of Na+, and are believed to be externally mixed with the acidic sulfate aerosols. Nitrate was observed only on sea-salt particles, consistent with adsorption of HNO3 on non-acidic sea-salt aerosols, responsible partly for the Cl- deficit. Dust particles appeared to play a minor role judging from the small volume differences between that derived from the observed mass concentrations and that calculated based on particle size distributions. Because SO42- concentrations in the study domain were substantial (~0.5 - ~3 μg/m3) with a strong gradient (highest near the shore decreasing with distance from land), and the ocean-emitted dimethylsulfide and its unique oxidation product, CH3SO3-, were very low (i.e., ≤ 40 parts per trillion and <0.05 μg/m3, respectively), the observed SO42- aerosols are believed to be primarily of terrestrial origin. Back trajectory calculations indicate sulfur emissions from smelters and power plants along coastal regions of Peru and Chile are the main sources of these SO4

  7. The importance of aerosol mixing state and size-resolved composition on CCN concentration and the variation of the importance with atmospheric aging of aerosols

    SciTech Connect

    Wang, J.; Cubison, M. J.; Aiken, A. C.; Jimenez, J. L.; Collins, D. R.

    2010-05-01

    Aerosol microphysics, chemical composition, and CCN concentrations were measured at the T0 urban supersite in Mexico City during Megacity Initiative: Local and Global Research Observations (MILAGRO) in March 2006. The aerosol size distribution and composition often showed strong diurnal variation associated with traffic emissions and aging of aerosols through coagulation and local photochemical production of secondary aerosol species. CCN concentrations (N{sub CCN}) are derived using Kohler theory from the measured aerosol size distribution and various simplified aerosol mixing state and chemical composition, and are compared to concurrent measurements at five supersaturations ranging from 0.11% to 0.35%. The influence of assumed mixing state on calculated N{sub CCN} is examined using both aerosols observed during MILAGRO and representative aerosol types. The results indicate that while ambient aerosols often consist of particles with a wide range of compositions at a given size, N{sub CCN} may be derived within {approx}20% assuming an internal mixture (i.e., particles at a given size are mixtures of all participating species, and have the identical composition) if great majority of particles has an overall {kappa} (hygroscopicity parameter) value greater than 0.1. For a non-hygroscopic particle with a diameter of 100 nm, a 3 nm coating of sulfate or nitrate is sufficient to increase its {kappa} from 0 to 0.1. The measurements during MILAGRO suggest that the mixing of non-hygroscopic primary organic aerosol (POA) and black carbon (BC) particles with photochemically produced hygroscopic species and thereby the increase of their {kappa} to 0.1 take place in a few hours during daytime. This rapid process suggests that during daytime, a few tens of kilometers away for POA and BC sources, N{sub CCN} may be derived with sufficient accuracy by assuming an internal mixture, and using bulk chemical composition. The rapid mixing also indicates that, at least for very active

  8. Sea Spray Aerosol Structure and Composition Using Cryogenic Transmission Electron Microscopy

    PubMed Central

    2016-01-01

    The composition and surface properties of atmospheric aerosol particles largely control their impact on climate by affecting their ability to uptake water, react heterogeneously, and nucleate ice in clouds. However, in the vacuum of a conventional electron microscope, the native surface and internal structure often undergo physicochemical rearrangement resulting in surfaces that are quite different from their atmospheric configurations. Herein, we report the development of cryogenic transmission electron microscopy where laboratory generated sea spray aerosol particles are flash frozen in their native state with iterative and controlled thermal and/or pressure exposures and then probed by electron microscopy. This unique approach allows for the detection of not only mixed salts, but also soft materials including whole hydrated bacteria, diatoms, virus particles, marine vesicles, as well as gel networks within hydrated salt droplets—all of which will have distinct biological, chemical, and physical processes. We anticipate this method will open up a new avenue of analysis for aerosol particles, not only for ocean-derived aerosols, but for those produced from other sources where there is interest in the transfer of organic or biological species from the biosphere to the atmosphere. PMID:26878061

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

    SciTech Connect

    Novick, Vincent J.

    1997-12-01

    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.

  10. 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.

  11. Lake spray aerosol generation: a method for producing representative particles from freshwater wave breaking

    NASA Astrophysics Data System (ADS)

    May, Nathaniel W.; Axson, Jessica L.; Watson, Alexa; Pratt, Kerri A.; Ault, Andrew P.

    2016-09-01

    Wave-breaking action in bodies of freshwater produces atmospheric aerosols via a similar mechanism to sea spray aerosol (SSA) from seawater. The term lake spray aerosol (LSA) is proposed to describe particles formed by this mechanism, which have been observed over the Laurentian Great Lakes. Though LSA has been identified from size distribution measurements during a single measurement campaign, no measurements of LSA composition or relationship to bubble-bursting dynamics have been conducted. An LSA generator utilizing a plunging jet, similar to many SSA generators, was constructed for the generation of aerosol from freshwater samples and model salt solutions. To evaluate this new generator, bubble and aerosol number size distributions were measured for salt solutions representative of freshwater (CaCO3) and seawater (NaCl) at concentrations ranging from that of freshwater to seawater (0.05-35 g kg-1), synthetic seawater (inorganic), synthetic freshwater (inorganic), and a freshwater sample from Lake Michigan. Following validation of the bubble and aerosol size distributions using synthetic seawater, a range of salt concentrations were investigated. The systematic studies of the model salts, synthetic freshwater, and Lake Michigan sample indicate that LSA is characterized by a larger number size distribution mode diameter of 300 nm (lognormal), compared to seawater at 110 nm. Decreasing salt concentrations from seawater to freshwater led to greater bubble coalescence and formation of larger bubbles, which generated larger particles and lower aerosol number concentrations. This resulted in a bimodal number size distribution with a primary mode (180 ± 20 nm) larger than that of SSA, as well as a secondary mode (46 ± 6 nm) smaller than that of SSA. This new method for studying LSA under isolated conditions is needed as models, at present, utilize SSA parameterizations for freshwater systems, which do not accurately predict the different size distributions observed

  12. Extraction of Optical Constants from Mid-IR Spectra of Small Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Segal-Rosenheimer, M.; Dubowski, Y.; Linker, R.

    2008-12-01

    Aerosol particles directly influence the Earth's radiation budget by absorbing and scattering incident short- wave (solar) radiation and long-wave terrestrial radiation. Broadband infrared measurements can provide valuable information on aerosol's composition and size distribution. However, quantitative analysis of mid- infrared aerosol extinction spectra in terms of their characteristics relies on complex refractive indices for the various aerosol constituents. Derivation of such optical constants is complicated, especially in the mid- infrared region, mainly due to the great variability of the imaginary part (k) of the complex refractive index N, and its influence on the real part (n). Most of previously reported methods for determining these constants (Wagner et al., 2005; Dohm et al., 2004; Earle et al, 2006) use aerosols with size distributions for which scattering occurs in the spectral range of the measurement, and so the explicit Mie theory calculations for the scattering and absorption efficiencies are required. These calculations necessitate some assumptions on the particles size distribution and an initial guess of the k spectrum in order to extract the optical properties from the acquired spectra. Also, the solution uniqueness relies on the fact that the particles are large enough. In the present work, we seek to simplify the above procedure and use small particles' spectra of known size distributions to deduce the optical constants. For particles (such as poly-disperse aerosols) having geometric mean of less than 0.15 μm, absorbance spectra in the mid-infrared range do not show any scattering features. Therefore, Rayleigh theory can be used to extract the imaginary part of the complex function f, where f=[(N2-1)/(N2+2)]. The real part of the f function is then extracted using the Kramers-Kronig transformation and the n and k can be derived using the relation between f, ɛ (complex dielectric function). k and n (Bohren and Huffman, 1983). The method

  13. 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.

  14. Investigations of Physicochemical Properties of Size-Resolved, Subsaturated, Atmospheric Aerosol Particles: Instrument Development, Field Measurements, and Data Analysis

    NASA Astrophysics Data System (ADS)

    Shingler, Taylor

    Aerosol particle properties and their impact on air quality, clouds, and the hydrologic cycle remain a critically important factor for the understanding of our atmosphere. Particle hygroscopic growth leads to impacts on direct and indirect radiative forcing properties, the likelihood for particles to act as cloud condensation nuclei, and aerosol-cloud interactions. Current instruments measuring hygroscopic growth have a number of limitations, lacking either the ability to measure size-resolved particles or process samples at a fast enough resolution to be suitable for airborne deployment. Advanced in-situ airborne particle retrieval and measurements of aerosol hygroscopic growth and scattering properties are analyzed and discussed. To improve the analysis of cloud nuclei particles, an updated counterflow virtual impact inlet was characterized and deployed during the 2011 E-PEACE field campaign. Theoretical and laboratory based cut size diameters were determined and validated against data collected from an airborne platform. In pursuit of higher quality aerosol particle hygroscopicity measurements, a newer instrument, the differential aerosol sizing and hygroscopicity probe (DASH-SP) has been developed in the recent past and only flown on a handful of campaigns. It has been proven to provide quality, rapid, size-resolved hygroscopic growth factor data, but was further improved into a smaller form factor making it easier for deployment on airborne platforms. It was flown during the 2013 SEAC4RS field campaign and the data was analyzed to composite air mass based hygroscopicity and refractive index (real portion only) statistics. Additionally, a comparison of bulk and size-resolved hygroscopic growth measurements was conducted. Significant findings include a potential particle size bias on bulk scattering measurements as well as a narrow range of ambient real portion of refractive index values. An investigation into the first reported ambient hygroscopicity

  15. Lidar determination of the composition of atmosphere aerosols

    NASA Technical Reports Server (NTRS)

    Wright, M. L.

    1980-01-01

    Theoretical and experimental studies of the feasibility of using DIfferential SCatter (DISC) lidar to measure the composition of atmospheric aerosols are described. This technique involves multiwavelength measurements of the backscatter cross section of aerosols in the middle infrared, where a number of materials display strong restrahlen features that significantly modulate the backscatter spectrum. The theoretical work indicates that a number of materials of interest, including sulfuric acid, ammonium sulfate, and silicates, can be discriminated among with a CO2 lidar. An initial evaluation of this procedure was performed in which cirrus clouds and lower altitude tropospheric aerosols were developed. The observed ratio spectrum of the two types of aerosol displays structure that is in crude accord with theoretical expectations.

  16. In-situ determination of atmospheric aerosol composition as a function of hygroscopic growth

    SciTech Connect

    Herich, Hanna; Kammermann, Lukas; Gysel, Martin; Weingartner, E.; Baltensperger, Urs; Lohmann, U.; Cziczo, Daniel J.

    2008-08-30

    An in-situ measurement setup to determine the chemical composition of aerosols as a function of hygroscopicity is presented. This has been done by connecting a custom-built Hygroscopicity Tandem Differential Mobility Analyzer (HTDMA) and an Aerosol Time-of-Flight Mass Spectrometer (ATOFMS), commercially available from TSI (Model 3800). Single particle bipolar mass spectra from aerosols leaving the HTDMA could thus be obtained as a function of the hygroscopic growth factor. For these studies the HTDMA was set at a relative humidity of 82% and particles with a dry diameter of 260 nm were selected. The setup was first laboratory tested after which field experiments were performed. Two datasets were obtained during wintertime 2007 in Switzerland: the first in the urban Zurich environment and the other at the remote high alpine research station Jungfraujoch (JFJ). In Zurich several thousand mass spectra were obtained in less than two days of sampling due to a high aerosol loading. At the JFJ, due to low particle concentrations in free tropospheric airmasses, a longer sampling period was required. Both in Zurich and at the JFJ two different growth factor modes were observed. Results from these two locations show that most aerosol particles were a mixture of several compounds. A large contribution of organics and combustion species was found in the less hygroscopic growth mode for both locations. Non-combustion refractory material (e.g. metals, mineral dust, and fly ash) was also highly enhanced in the non-hygroscopic particles. Sulfate, normally considered highly soluble, was found to be a constituent in almost all particles independent of their hygroscopic growth factor.

  17. Chemical composition, main sources and temporal variability of PM1 aerosols in southern African grassland

    NASA Astrophysics Data System (ADS)

    Tiitta, P.; Vakkari, V.; Josipovic, M.; Croteau, P.; Beukes, J. P.; van Zyl, P. G.; Venter, A. D.; Jaars, K.; Pienaar, J. J.; Ng, N. L.; Canagaratna, M. R.; Jayne, J. T.; Kerminen, V.-M.; Kulmala, M.; Laaksonen, A.; Worsnop, D. R.; Laakso, L.

    2013-06-01

    Southern Africa is a significant source region of atmospheric pollution, yet long-term data on pollutant concentrations and properties from this region are rather limited. A recently established atmospheric measurement station in South Africa, Welgegund, is strategically situated to capture regional background emissions, as well as emissions from the major source regions in the interior of South Africa. We measured non-refractive submicron aerosols (NR-PM1) and black carbon over a one year period in Welgegund, and investigated the seasonal and diurnal patterns of aerosol concentration levels, chemical composition, acidity and oxidation level. Based on air mass back trajectories, four distinct source regions were determined for NR-PM1. Supporting data utilized in our analysis included particle number size distributions, aerosol absorption, trace gas concentrations, meteorological variables and the flux of carbon dioxide. The dominant submicron aerosol constituent during the dry season was organic aerosol, reflecting high contribution from savannah fires and other combustion sources. Organic aerosol concentrations were lower during the wet season, presumably due to wet deposition as well as reduced emissions from combustion sources. Sulfate concentrations were usually high and exceeded organic aerosol concentrations when air-masses were transported over regions containing major point sources. Sulfate and nitrate concentrations peaked when air masses passed over the industrial Highveld (iHV) area. In contrast, concentrations were much lower when air masses passed over the cleaner background (BG) areas. Air masses associated with the anti-cyclonic recirculation (ACBIC) source region contained largely aged OA. Positive Matrix Factorization (PMF) analysis of aerosol mass spectra was used to characterize the organic aerosol (OA) properties. The factors identified were oxidized organic aerosols (OOA) and biomass burning organic aerosols (BBOA) in the dry season and low

  18. Investigating the Influence of Sea Spray Particle Composition on Water Uptake

    NASA Astrophysics Data System (ADS)

    Cappa, C. D.; Forestieri, S.; Cornwell, G.; Helgestad, T.; Moore, K.; Lee, C.; Novak, G.; Sultana, C. M.; Wang, X.; Bertram, T. H.; Prather, K. A.

    2015-12-01

    Sea spray aerosol (SSA) particles influence climate by scattering solar radiation and serving as cloud seeds. Their specific influence depends, in part, on the extent to which they interact with water, which depends importantly on particle composition. The composition of freshly-emitted SSA particles is connected to the water (ocean) composition—especially biological activity—and the SSA production mechanism. Results from both field measurements and a suite of laboratory mesocosm experiments utilizing real ocean water and stimulated phytoplankton blooms with realistic simulated wave breaking will be discussed to demonstrate the complex relationships between nascent SSA particle water uptake and particle and source water composition.

  19. If I know the aerosol compositional model identifier, how can I get information about the corresponding aerosol model?

    Atmospheric Science Data Center

    2014-12-08

    ... (APOP) and the Mixture files. The Mixture file lists the pure particles in each model identifier. The APOP then gives the detailed information for the pure particles. More information on the MISR aerosol model is available from ...

  20. 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.

  1. Source apportionment of aerosol particles near a steel plant by electron microscopy.

    PubMed

    Ebert, Martin; Müller-Ebert, Dörthe; Benker, Nathalie; Weinbruch, Stephan

    2012-12-01

    The size, morphology and chemical composition of 37,715 individual particles collected over 22 sampling days in the vicinity of a large integrated steel production were studied by scanning and transmission electron microscopy. Based on the morphology, chemistry and beam stability the particles were classified into the following fourteen groups: silicates, sea salt, calcium sulfates, calcium carbonates, carbonate-silicate mixtures, sulfate-silicate mixtures, iron oxides, iron mixtures, metal oxide-metals, complex secondary particles, soot, Cl-rich particles, P-rich particles, and other particles. The majority of iron oxide (≈85%) and metal oxide-metal (≈70%) particles as well as ≈20% of the silicate particles are fly ashes from high temperature processes. The emissions from the steel work are dominated by iron oxide particles. For source apportionment, seven source categories and two sectors of local wind direction (industrial and urban background) were distinguished. In both sectors PM₁₀ consists of four major source categories: 35% secondary, 20% industrial, 17% soil and 16% soot in the urban background sector compared to 45% industrial, 20% secondary, 13% soil, and 9% soot in the industrial sector. As the secondary and the soot components are higher in the urban background sector than in the industrial sector, it is concluded that both components predominantly originate from urban background sources (traffic, coal burning, and domestic heating). Abatement measures should not only focus on the steel work but should also include the urban background aerosol.

  2. Use of stable carbon and nitrogen isotope ratios in size segregated aerosol particles for the O/I penetration evaluation

    NASA Astrophysics Data System (ADS)

    Garbaras, Andrius; Garbariene, Inga; Masalaite, Agne; Ceburnis, Darius; Krugly, Edvinas; Kvietkus, Kestutis; Remeikis, Vidmantas; Martuzevicius, Dainius

    2015-04-01

    Stable carbon and nitrogen isotope ratio are successfully used in the atmospheric aerosol particle source identification [1, 2], transformation, pollution [3] research. The main purpose of this study was to evaluate the penetration of atmospheric aerosol particles from outdoor to indoor using stable carbon and nitrogen isotope ratios. Six houses in Kaunas (Lithuania) were investigated during February and March 2013. Electrical low pressure impactor was used to measure in real time concentration and size distribution of outdoor aerosol particles. ELPI+ includes 15 channels covering the size range from 0.017 to 10.0 µm. The 25 mm diameter aluminium foils were used to collect aerosol particles. Gravimetric analysis of samples was made using microbalance. In parallel, indoor aerosol samples were collected with a micro-orifice uniform deposition impactor (MOUDI model 110), where the aerosol particles were separated with the nominal D50 cut-off sizes of 0.056, 0.1, 0.18,0.32,0.56, 1.0, 1.8, 3.2, 5.6, 10, 18 μm for impactor stages 1-11, respectively. The impactor was run at a flow rate of 30 L/min. Air quality meters were used to record meteorological conditions (temperature, relative humidity) during the investigated period. All aerosol samples were analyzed for total carbon (TC) and total nitrogen (TN) contents and their isotopic compositions using elemental analyzer (EA) connected to the stable isotope ratio mass spectrometer (IRMS). TC concentration in indoors ranged from 1.5 to 247.5 µg/m3. During the sampling period outdoors TN levels ranged from 0.1 to 10.9 µg/m3. The obtained outdoor δ13C(PM2.5) values varied from -24.21 to -26.3‰, while the δ15N values varied from 2.4 to 11.1 ‰ (average 7.2±2.5 ‰). Indoors carbonaceous aerosol particles were depleted in 13C compared to outdoors in all sampling sites. This depletion in δ13C varied from 0.1 to 3.2 ‰. We think that this depletion occurs due ongoing chemical reactions (oxidation) when aerosol

  3. Computation of Phase Equilibria, State Diagrams and Gas/Particle Partitioning of Mixed Organic-Inorganic Aerosols

    NASA Astrophysics Data System (ADS)

    Zuend, A.; Marcolli, C.; Peter, T.

    2009-04-01

    The chemical composition of organic-inorganic aerosols is linked to several processes and specific topics in the field of atmospheric aerosol science. Photochemical oxidation of organics in the gas phase lowers the volatility of semi-volatile compounds and contributes to the particulate matter by gas/particle partitioning. Heterogeneous chemistry and changes in the ambient relative humidity influence the aerosol composition as well. Molecular interactions between condensed phase species show typically non-ideal thermodynamic behavior. Liquid-liquid phase separations into a mainly polar, aqueous and a less polar, organic phase may considerably influence the gas/particle partitioning of semi-volatile organics and inorganics (Erdakos and Pankow, 2004; Chang and Pankow, 2006). Moreover, the phases present in the aerosol particles feed back on the heterogeneous, multi-phase chemistry, influence the scattering and absorption of radiation and affect the CCN ability of the particles. Non-ideal thermodynamic behavior in mixtures is usually described by an expression for the excess Gibbs energy, enabling the calculation of activity coefficients. We use the group-contribution model AIOMFAC (Zuend et al., 2008) to calculate activity coefficients, chemical potentials and the total Gibbs energy of mixed organic-inorganic systems. This thermodynamic model was combined with a robust global optimization module to compute potential liquid-liquid (LLE) and vapor-liquid-liquid equilibria (VLLE) as a function of particle composition at room temperature. And related to that, the gas/particle partitioning of semi-volatile components. Furthermore, we compute the thermodynamic stability (spinodal limits) of single-phase solutions, which provides information on the process type and kinetics of a phase separation. References Chang, E. I. and Pankow, J. F.: Prediction of activity coefficients in liquid aerosol particles containing organic compounds, dissolved inorganic salts, and water - Part

  4. Aerosol microphysics simulations of the Mt. Pinatubo eruption with the UKCA composition-climate model

    NASA Astrophysics Data System (ADS)

    Dhomse, S. S.; Emmerson, K. M.; Mann, G. W.; Bellouin, N.; Carslaw, K. S.; Chipperfield, M. P.; Hommel, R.; Abraham, N. L.; Telford, P.; Braesicke, P.; Dalvi, M.; Johnson, C. E.; O'Connor, F.; Morgenstern, O.; Pyle, J. A.; Deshler, T.; Zawodny, J. M.; Thomason, L. W.

    2014-01-01

    We have enhanced the capability of a microphysical aerosol-chemistry module to simulate the atmospheric aerosol and precursor gases for both tropospheric and stratospheric conditions. Using the Mount Pinatubo eruption (June 1991) as a test case, we evaluate simulated aerosol properties in a composition-climate model against a range of satellite and in-situ observations. Simulations are performed assuming an injection of 20 Tg SO2 at 19-27 km in tropical latitudes, without any radiative feedback from the simulated aerosol. In both quiescent and volcanically perturbed conditions, simulated aerosol properties in the lower stratosphere show reasonable agreement with the observations. The model captures the observed timing of the maximum aerosol optical depth (AOD) and its decay timescale in both tropics and Northern Hemisphere (NH) mid-latitudes. There is also good qualitative agreement with the observations in terms of spatial and temporal variation of the aerosol effective radius (Reff), which peaks 6-8 months after the eruption. However, the model shows significant biases against some observational data sets. Simulated AOD and Surface Area Density (SAD) in the tropics are substantially higher than the gap-filled satellite data products during the first 6 months after the eruption. The model shows consistently weaker enhancement in Reff compared to satellite and in-situ measurements. Simulated aerosol particle size distribution is also compared to NH mid-latitude in-situ balloon sounding measurements of size-resolved number concentrations. Before the eruption, the model captures the observed profiles of lower stratospheric particle number concentrations with radii larger than 5, 150 and 250 nm (N5, N150 and N250) very well. However, in the first 6 months after the eruption, the model shows high bias in N5 concentrations in the lower stratosphere, suggesting too strong nucleation. Following particle growth via condensation and coagulation, this bias in the finest

  5. Aerosol composition, chemistry, and source characterization during the 2008 VOCALS Experiment

    SciTech Connect

    Lee, Y.; Springston, S.; Jayne, J.; Wang, J.; Senum, G.; Hubbe, J.; Alexander, L.; Brioude, J.; Spak, S.; Mena-Carrasco, M.; Kleinman, L.; Daum, P.

    2010-03-15

    Chemical composition of fine aerosol particles over the northern Chilean coastal waters was determined onboard the U.S. DOE G-1 aircraft during the VOCALS (VAMOS Ocean-Cloud-Atmosphere-Land Study) field campaign between October 16 and November 15, 2008. SO42-, NO3-, NH4+, and total organics (Org) were determined using an Aerodyne Aerosol Mass Spectrometer, and SO42-, NO3-, NH4+, Na+, Cl-, CH3SO3-, Mg2+, Ca2+, and K+ were determined using a particle-into-liquid sampler-ion chromatography technique. The results show the marine boundary layer (MBL) aerosol mass was dominated by non- sea-salt SO42- followed by Na+, Cl-, Org, NO3-, and NH4+, in decreasing importance; CH3SO3-, Ca2+, and K+ rarely exceeded their respective limits of detection. The SO42- aerosols were strongly acidic as the equivalent NH4+ to SO42- ratio was only {approx}0.25 on average. NaCl particles, presumably of sea-salt origin, showed chloride deficits but retained Cl- typically more than half the equivalency of Na+, and are externally mixed with the acidic sulfate aerosols. Nitrate was observed only on sea-salt particles, consistent with adsorption of HNO3 on sea-salt aerosols, responsible for the Cl- deficit. Dust particles appeared to play a minor role, judging from the small volume differences between that derived from the observed mass concentrations and that calculated based on particle size distributions. Because SO42- concentrations were substantial ({approx}0.5 - {approx}3 {micro}g/m3) with a strong gradient (highest near the shore), and the ocean-emitted dimethylsulfide and its unique oxidation product, CH3SO3-, were very low (i.e., {le} 40 parts per trillion and <0.05 {micro}g/m3, respectively), the observed SO42- aerosols are believed to be primarily of terrestrial origin. Back trajectory calculations indicate sulfur emissions from smelters and power plants along coastal regions of Peru and Chile are the main sources of these SO4- aerosols. However, compared to observations, model

  6. Characterization of the Aerosol-based Synthesis of Uranium Particles as a Potential Reference Material for Micro Analytical Methods.

    PubMed

    Middendorp, Ronald; Dürr, Martin; Knott, Alexander; Pointurier, Fabien; Ferreira Sanchez, Dario; Samson, Valerie Ann; Grolimund, Daniel

    2017-03-27

    A process for production of micrometer-sized particles composed of uranium oxide using aerosol spray pyrolysis is characterized with respect to the various production parameters. The aerosol is generated using a vibrating orifice aerosol generator providing monodisperse droplets, which are oxidized in a subsequent heat treatment. The final particles are characterized with micro analytical methods to determine size, shape, internal morphology, chemical and structural properties in order to assess the suitability of the produced particles as a reference material for micro analytical methods, in particular for mass-spectrometry. It is demonstrated that physico-chemical processes during particle formation and the heat treatment to chemically transform particles into an oxide strongly influence the particle shape and the internal morphology. Synchrotron μ-X-ray based techniques combined with μ-Raman spectroscopy have been applied to demonstrate that the obtained micro particles consist of a triuranium octoxide phase. Our studies demonstrate that the process is capable of delivering spherical particles with determined uniform size and ele-mental as well as chemical composition. The particles therefore represent a suitable base material to fulfill the homogeneity and stability requirements of a reference material for micro analytical methods applied in, for example, international safeguards or nuclear forensics.

  7. 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.

  8. 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.

  9. 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.

  10. Characteristics and Composition of Atmospheric Aerosols in Phimai, Central Thailand During BASE-ASIA

    NASA Technical Reports Server (NTRS)

    Li, Can; Tsay, Si-Chee; Hsu, N. Christina; Kim, Jin Young; Howell, Steven G.; Huebert, Barry J.; Ji, Qiang; Jeong, Myeong-Jae; Wang, Sheng-Hsiang; Hansell, Richard A.; Bell, Shaun W.

    2012-01-01

    +/- 8 Mm(exp -1); PM(sub 10) concentration: 33 +/- 17 miro-g/ cubic m and dominated by submicron particles. Major aerosol compounds included carbonaceous (OC: 9.5 +/- 3.6miro-g/ cubic m; EC: 2.0 2.3 miro-g/ cubic m and secondary species (SO4(2-): 6.4 +/- 3.7 miro-g/ cubic m, NH4(+): 2.2 +/- 1.3 miro-g/ cubic m). While the site was seldom under the direct influence of large forest fires to its north, agricultural fires were ubiquitous during the experiment, as suggested by the substantial concentration of K+ (0.56 +/- 0.33 micro-g/ cubic m). Besides biomass burning, aerosols in Phimai during the experiment were also strongly influenced by industrial and vehicular emissions from the Bangkok metropolitan region and long-range transport from southern China. High humidity played an important role in determining the aerosol composition and properties in the region. Sulfate was primarily formed via aqueous phase reactions, and hygroscopic growth could enhance the aerosol light scattering by up to 60%, at the typical morning RH level of 85%. The aerosol single scattering albedo demonstrated distinct diurnal variation, ranging from 0.86 +/- 0.04 in the evening to 0.92 +/- 0.02 in the morning. This experiment marks the first time such comprehensive characterization of aerosols was made for rural central Thailand. Our results indicate that aerosol pollution has developed into a regional problem for northern Indochina, and may become more severe as the region's population and economy continue to grow.

  11. Measurement of the nucleation of atmospheric aerosol particles.

    PubMed

    Kulmala, Markku; Petäjä, Tuukka; Nieminen, Tuomo; Sipilä, Mikko; Manninen, Hanna E; Lehtipalo, Katrianne; Dal Maso, Miikka; Aalto, Pasi P; Junninen, Heikki; Paasonen, Pauli; Riipinen, Ilona; Lehtinen, Kari E J; Laaksonen, Ari; Kerminen, Veli-Matti

    2012-09-01

    The formation of new atmospheric aerosol particles and their subsequent growth have been observed frequently at various locations all over the world. The atmospheric nucleation rate (or formation rate) and growth rate (GR) are key parameters to characterize the phenomenon. Recent progress in measurement techniques enables us to measure atmospheric nucleation at the size (mobility diameter) of 1.5 (±0.4) nm. The detection limit has decreased from 3 to 1 nm within the past 10 years. In this protocol, we describe the procedures for identifying new-particle-formation (NPF) events, and for determining the nucleation, formation and growth rates during such events under atmospheric conditions. We describe the present instrumentation, best practices and other tools used to investigate atmospheric nucleation and NPF at a certain mobility diameter (1.5, 2.0 or 3.0 nm). The key instruments comprise devices capable of measuring the number concentration of the formed nanoparticles and their size, such as a suite of modern condensation particle counters (CPCs) and air ion spectrometers, and devices for characterizing the pre-existing particle number concentration distribution, such as a differential mobility particle sizer (DMPS). We also discuss the reliability of the methods used and requirements for proper measurements and data analysis. The time scale for realizing this procedure is 1 year.

  12. Determining aerosol particles by in-air micro-IL analysis combined with micro-PIXE

    NASA Astrophysics Data System (ADS)

    Kada, Wataru; Satoh, Takahiro; Yokoyama, Akihito; Koka, Masashi; Kamiya, Tomihiro

    2013-07-01

    A new external ion microbeam ion luminescence (micro-IL) imaging system was developed on a microbeam line of a 3 MV single-ended accelerator at the TIARA facility of the Japan Atomic Energy Agency. Micro-IL was combined with an in-air micro-PIXE (particle-induced X-ray emission) system to determine the chemical composition and structures of microscopic airborne particles of several micrometers in size. The hardware and software for the combined in-air micro-IL analysis system, called ion luminescence microscopic imaging and spectroscopy (ILUMIS), were studied. Wavelength-dispersive optics, including a collimator lens, a monochromator, and a photon-counting photomultiplier, were installed on the beam line. The signal processing of the IL photon signals, which were collected as spectra and two-dimensional microscopic images, was examined. Several aerosol particles were characterized to demonstrate the ILUMIS/PIXE combined analysis. The external microbeam ILUMIS analysis method provided a variety of information on the chemical and elemental composition of the micrometer-sized aerosol targets under ambient atmospheric conditions.

  13. Measurements of the aerosol chemical composition and mixing state in the Po Valley using multiple spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Decesari, S.; Allan, J.; Plass-Duelmer, C.; Williams, B. J.; Paglione, M.; Facchini, M. C.; O'Dowd, C.; Harrison, R. M.; Gietl, J. K.; Coe, H.; Giulianelli, L.; Gobbi, G. P.; Lanconelli, C.; Carbone, C.; Worsnop, D.; Lambe, A. T.; Ahern, A. T.; Moretti, F.; Tagliavini, E.; Elste, T.; Gilge, S.; Zhang, Y.; Dall'Osto, M.

    2014-11-01

    The use of co-located multiple spectroscopic techniques can provide detailed information on the atmospheric processes regulating aerosol chemical composition and mixing state. So far, field campaigns heavily equipped with aerosol mass spectrometers have been carried out mainly in large conurbations and in areas directly affected by their outflow, whereas lesser efforts have been dedicated to continental areas characterised by a less dense urbanisation. We present here the results obtained at a background site in the Po Valley, Italy, in summer 2009. For the first time in Europe, six state-of-the-art spectrometric techniques were used in parallel: aerosol time-of-flight mass spectrometer (ATOFMS), two aerosol mass spectrometers (high-resolution time-of-flight aerosol mass spectrometer - HR-ToF-AMS and soot particle aerosol mass spectrometer - SP-AMS), thermal desorption aerosol gas chromatography (TAG), chemical ionisation mass spectrometry (CIMS) and (offline) proton nuclear magnetic resonance (1H-NMR) spectroscopy. The results indicate that, under high-pressure conditions, atmospheric stratification at night and early morning hours led to the accumulation of aerosols produced by anthropogenic sources distributed over the Po Valley plain. Such aerosols include primary components such as black carbon (BC), secondary semivolatile compounds such as ammonium nitrate and amines and a class of monocarboxylic acids which correspond to the AMS cooking organic aerosol (COA) already identified in urban areas. In daytime, the entrainment of aged air masses in the mixing layer is responsible for the accumulation of low-volatility oxygenated organic aerosol (LV-OOA) and also for the recycling of non-volatile primary species such as black carbon. According to organic aerosol source apportionment, anthropogenic aerosols accumulating in the lower layers overnight accounted for 38% of organic aerosol mass on average, another 21% was accounted for by aerosols recirculated in

  14. Long-term Chemical Characterization of Submicron Aerosol Particles in the Amazon Forest - ATTO Station

    NASA Astrophysics Data System (ADS)

    Carbone, S.; Brito, J.; Rizzo, L. V.; Holanda, B. A.; Cirino, G. G.; Saturno, J.; Krüger, M. L.; Pöhlker, C.; Ng, N. L.; Xu, L.; Andreae, M. O.; Artaxo, P.

    2015-12-01

    The study of the chemical composition of aerosol particles in the Amazon forest represents a step forward to understand the strong coupling between the atmosphere and the forest. For this reason submicron aerosol particles were investigated in the Amazon forest, where biogenic and anthropogenic aerosol particles coexist at the different seasons (wet/dry). The measurements were performed at the ATTO station, which is located about 150 km northeast of Manaus. At ATTO station the Aerosol chemical speciation monitor (ACSM, Aerodyne) and the Multiangle absorption photometer (MAAP, Thermo 5012) have been operated continuously from March 2014 to July 2015. In this study, long-term measurements (near-real-time, ~30 minutes) of PM1 chemical composition were investigated for the first time in this environment.The wet season presented lower concentrations than the dry season (~5 times). In terms of chemical composition, both seasons were dominated by organics (75 and 63%) followed by sulfate (11 and 13%). Nitrate presented different ratio values between the mass-to-charges 30 to 46 (main nitrate fragments) suggesting the presence of nitrate as inorganic and organic nitrate during both seasons. The results indicated that about 75% of the nitrate signal was from organic nitrate during the dry season. In addition, several episodes with elevated amount of chloride, likely in the form of sea-salt from the Atlantic Ocean, were observed during the wet season. During those episodes, chloride comprised up to 7% of the PM1. During the dry season, chloride was also observed; however, with different volatility, which suggested that Chloride was present in different form and source. Moreover, the constant presence of sulfate and BC during the wet season might be related to biomass burning emissions from Africa. BC concentration was 2.5 times higher during the dry season. Further characterization of the organic fraction was accomplished with the positive matrix factorization (PMF), which

  15. Linking Remotely Sensed Aerosol Types to Their Chemical Composition

    NASA Technical Reports Server (NTRS)

    Dawson, Kyle William; Kacenelenbogen, Meloe S.; Johnson, Matthew S.; Burton, Sharon P.; Hostetler, Chris A.; Meskhidze, Nicholas

    2016-01-01

    Aerosol types measured during the Ship-Aircraft Bio-Optical Research (SABOR) experiment are related to GEOS-Chem model chemical composition. The application for this procedure to link model chemical components to aerosol type is desirable for understanding aerosol evolution over time. The Mahalanobis distance (DM) statistic is used to cluster model groupings of five chemical components (organic carbon, black carbon, sea salt, dust and sulfate) in a way analogous to the methods used by Burton et al. [2012] and Russell et al. [2014]. First, model-to-measurement evaluation is performed by collocating vertically resolved aerosol extinction from SABOR High Spectral Resolution LiDAR (HSRL) to the GEOS-Chem nested high-resolution data. Comparisons of modeled-to-measured aerosol extinction are shown to be within 35% +/- 14%. Second, the model chemical components are calculation into five variables to calculate the DM and cluster means and covariances for each HSRL-retrieved aerosol type. The layer variables from the model are aerosol optical depth (AOD) ratios of (i) sea salt and (ii) dust to total AOD, mass ratios of (iii) total carbon (i.e. sum of organic and black carbon) to the sum of total carbon and sulfate (iv) organic carbon to black carbon, and (v) the natural log of the aerosol-to-molecular extinction ratio. Third, the layer variables and at most five out of twenty SABOR flights are used to form the pre-specified clusters for calculating DM and to assign an aerosol type. After determining the pre-specified clusters, model aerosol types are produced for the entire vertically resolved GEOS-Chem nested domain over the United States and the model chemical component distributions relating to each type are recorded. Resulting aerosol types are Dust/Dusty Mix, Maritime, Smoke, Urban and Fresh Smoke (separated into 'dark' and 'light' by a threshold of the organic to black carbon ratio). Model-calculated DM not belonging to a specific type (i.e. not meeting a threshold

  16. Vertical distribution of non-volatile species of upper tropospheric and lower stratospheric aerosol observed by balloon-borne optical particle counter above Ny-Aalesund, Norway in the winter of 2015

    NASA Astrophysics Data System (ADS)

    Shiraishi, K.; Hayashi, M.; Shibata, T.; Neuber, R.; Ruhe, W.

    2015-12-01

    The polar lower stratosphere is the sink area of stratospheric global circulation. The composition, concentration and size distribution of aerosol in the polar stratosphere are considered to be strongly influenced by the transportations from mid-latitude to polar region and exchange of stratosphere to troposphere. In order to study the aerosol composition and size distribution in the Arctic stratosphere and the relationship between their aerosol microphysical properties and transport process, we carried out balloon-borne measurement of aerosol volatility above Ny-Aalesund, Norway in the winter of 2015. In our observation, two optical particle counters and a thermo denuder were suspended by one rubber balloon. A particle counter measured the heated aerosol size distribution (after heating at the temperature of 300 degree by the thermo denuder) and the other measured the ambient aerosol size distribution during the observation. The observation was carried out on 15 January, 2015. Balloon arrived at the height of 30km and detailed information of aerosol size distributions in upper troposphere and lower stratosphere for both heated aerosol and ambient aerosol were obtained. As a Result, the number ratio of non-volatile particles to ambient aerosol particles in lower stratosphere (11-15km) showed different feature in particle size range of fine mode (0.3particles to ambient aerosol particles were 1-3% in fine mode range and 7-20% in coarse mode range. They suggested that fine particles are composed dominantly of volatile species (probably sulfuric acid), and coarse particles are composed of non-volatile species such as minerals, sea-salts. In our presentation, we show the obtained aerosol size distribution and discuss the aerosol compositions and their transport process.

  17. Isotope source apportionment of carbonaceous aerosol as a function of particle size and thermal refractiveness

    NASA Astrophysics Data System (ADS)

    Masalaite, Agne; Holzinger, Rupert; Remeikis, Vidmantas; Röckmann, Thomas; Dusek, Ulrike

    2016-04-01

    The stable carbon isotopes can be used to get information about sources and processing of carbonaceous aerosol. We will present results from source apportionment of carbonaceous aerosol as a function of particle size thermal refractiveness. Separate source apportionment for particles smaller than 200 nm and for different carbon volatility classes are rarely reported and give new insights into aerosol sources in the urban environment. Stable carbon isotope ratios were measured for the organic carbon (OC) fraction and total carbon (TC) of MOUDI impactor samples that were collected on a coastal site (Lithuania) during the winter 2012 and in the city of Vilnius (Lithuania) during the winter of 2009. The 11 impactor stages spanned a size range from 0.056 to 18 μm, but only the 6 stages in the submicron range were analysed. The δ13C values of bulk total carbon (δ13CTC) were determined with an elemental analyser (Flash EA 1112) coupled with an isotope ratio mass spectrometer (Thermo Finnigan Delta Plus Advantage) (EA - IRMS). Meanwhile δ13COC was measured using thermal-desorption isotope ratio mass spectrometry (IRMS) system. This allows a rough separation of the more volatile OC fraction (desorbed in the oven of IRMS up to 250 0C) from the more refractory fraction (desorbed up to 400 0C). In this study we investigated the composition of organic aerosol desorbed from filter samples at different temperatures using the thermal-desorption proton-transfer-reaction mass spectrometry (TD-PTR-MS) technique. During winter-time in Lithuania we expect photochemistry and biogenic emissions to be of minor importance. The main sources of aerosol carbon should be fossil fuel and biomass combustion. In both sites, the coastal and the urban site, δ13C measurements give a clear indication that the source contributions differ for small and large particles. Small particles < 200 nm are depleted in 13C with respect to larger particles by 1 - 2 ‰Ṫhis shows that OC in small particle

  18. The role of biogenic, biomass burning and urban pollution aerosol particles in controlling key atmospheric processes in Amazonia

    NASA Astrophysics Data System (ADS)

    Artaxo, P.; Ferreira De Brito, J.; Barbosa, H. M.; Rizzo, L. V.; Sena, E. T.; Cirino, G.; Arana, A.; Yanez-Serrano, A. M.

    2013-05-01

    As part of the LBA (The Large Scale Biosphere Atmosphere Experiment in Amazonia) experiment, a research program run in the last 10 years had help to understand critical atmospheric processes in Amazonia. The vegetation in Amazonia is a direct source of aerosol particles to the atmosphere as well as a source of biogenic trace gases that generates particles trough gas-to-particle conversion. Biomass burning is also a large source of particles and trace gases to the atmosphere. Over the last 10 years, the LBA experiment has unveiled several key processes that control Amazonian composition and influence regional climate. A significant fraction (60-80%) of airborne particles can act as Cloud Condensation Nuclei (CCN), influencing cloud formation and development. The radiation balance is strongly influenced by biomass burning particles, and surface radiative forcing up to -250 w/m2 is measured. A network of 8 sites with AERONET sunphotometers measures aerosol optical depth (AOD) and derive aerosol size distribution and optical properties. Aerosols are composed of more than 70% of organic material, with significant absorption characteristics. The aerosol radiative forcing during the biomass burning season can reach very high values, and the increase in diffuse radiation increases the carbon uptake by the forest for AOD values smaller than 1.2 at 500nm. For large AOD, the solar flux is strongly reduced making the carbon uptake approach zero for AOD larger than 3.0. The composition of aerosols is mostly organic, with contribution of K, Ca, Si, and other trace elements. The aerosol has high capability to serve as Cloud Condensation Nuclei (CCN), contributing with high water vapor amounts to the significant cloud cover over the region. In the last 20 years, an urbanization process took over for most of the Amazonian region, increasing urban pollution that interacts with forest emissions to produce a quite unique pattern of aerosols and pollutants around large urban areas such

  19. Composition and major sources of organic compounds in urban aerosols

    NASA Astrophysics Data System (ADS)

    Bi, Xinhui; Simoneit, Bernd R. T.; Sheng, Guoying; Ma, Shexia; Fu, Jiamo

    Total suspended particles (TSP), collected during June 2002 to July 2003 in Guangzhou, a typical economically developed city in South China, were analyzed for the organic compound compositions using gas chromatography-mass spectrometry (GC/MS). Over 140 organic compounds were detected in the aerosols and grouped into different classes including n-alkanes, hopanoids, polycyclic aromatic hydrocarbons, alkanols, fatty acids, dicarboxylic acids excluding oxalic acid, polyols/polyacids, lignin products, phytosterols, phthalates and water-soluble sugars. The total amounts of the identified organic compounds including unresolved complex mixture (UCM) ranged from 3112 ng/m 3 in spring to 5116 ng/m 3 in winter, comprising on seasonal average 2.8% of TSP. Primary organic compounds peaked in winter although there are no heating systems burning fuels in Guangzhou. The highest saccharide levels occurred in fall due to agricultural activities. This study demonstrated that utilization of fossil fuels, biomass burning, soil resuspension and plastic/refuse burning are the major contributors to the identified organic compounds in the urban atmosphere of South China.

  20. 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

  1. 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, H. M.; Draper, D. C.; Ayres, B. R.; Ault, A.; Bondy, A.; Takahama, S.; Modini, R. L.; Baumann, K.; Edgerton, E.; Knote, C.; Laskin, A.; Wang, B.; Fry, J. L.

    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 HNO3 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.

  2. Individual Particle TOF-SIMS Imaging Analysis of Aerosol Collected During the April 2001 Asian Dust Event.

    NASA Astrophysics Data System (ADS)

    Peterson, R. E.

    2002-12-01

    Time of Flight Secondary Ion Mass Spectroscopy can provide information regarding the surface chemistry, including both organic and inorganic compounds, of individual atmospheric aerosol in themicrometer size range. X-ray analysis has commonly been used to analyze the composition of single particles but has several important limitations. Principally, X-ray analysis cannot be used to study organic compounds in the aerosol, it offers low sensitivity for light elements common in crustal material and it cannot distinguish isotopes. TOF-SIMS has the potential to provide superior performance in these areas. We have developed statistical image processing methods to allow extraction of individual particle mass spectra from TOF-SIMS images. In mid April 2001 a strong Asian dust event was tracked by the NASA TOMS satellite across the Pacific Ocean and into the continental United States. While Asian dust deposition is common in Hawaii, strong events characterized by significant visibility degradation have been much less frequently reported in the Rocky Mountain west. Samples were taken during and after the event at the University of Utah in Salt Lake City, Utah (SLC). Size segregated samples were collected on Al substrates using an 8 stage cascade impactor and total aerosol samples were collected with 47 mm Fluoropore filters. Surface and depth profile analysis of the particles was performed using a Phi Trift I TOF-SIMS instrument. Statistical methods, including PCA, mixture models and neural networks, were used to extract spectra of individual particles from the TOF-SIMS images and to classify particles based on their surface chemistry and depth profiles. Differences in both the chemistry and size distribution of the particles could be seen between the aerosol collected during the Asian dust event and aerosol collected post-event at the University of Utah site. Positive TOF-SIMS spectra of SLC urban aerosol were dominated by sub-micrometer organics, and negative spectra

  3. New approaches for the chemical and physical characterization of aerosols using a single particle mass spectrometry based technique

    NASA Astrophysics Data System (ADS)

    Spencer, Matthew Todd

    Aerosols affect the lives of people every day. They can decrease visibility, alter cloud formation and cloud lifetimes, change the energy balance of the earth and are implicated in causing numerous health problems. Measuring the physical and chemical properties of aerosols is essential to understand and mitigate any negative impacts that aerosols might have on climate and human health. Aerosol time-of-flight mass spectrometry (ATOFMS) is a technique that measures the size and chemical composition of individual particles in real time. The goal of this dissertation is to develop new and useful approaches for measuring the physical and/or chemical properties of particles using ATOFMS. This has been accomplished using laboratory experiments, ambient field measurements and sometimes comparisons between them. A comparison of mass spectra generated from petrochemical particles was made to light duty vehicle (LDV) and heavy duty diesel vehicle (HDDV) particle mass spectra. This comparison has given us new insight into how to differentiate between particles from these two sources. A method for coating elemental carbon (EC) particles with organic carbon (OC) was used to generate a calibration curve for quantifying the fraction of organic carbon and elemental carbon on particles using ATOFMS. This work demonstrates that it is possible to obtain quantitative chemical information with regards to EC and OC using ATOFMS. The relationship between electrical mobility diameter and aerodynamic diameter is used to develop a tandem differential mobility analyzer-ATOFMS technique to measure the effective density, size and chemical composition of particles. The method is applied in the field and gives new insight into the physical/chemical properties of particles. The size resolved chemical composition of aerosols was measured in the Indian Ocean during the monsoonal transition period. This field work shows that a significant fraction of aerosol transported from India was from biomass

  4. Aerosol mass spectrometry: particle-vaporizer interactions and their consequences for the measurements

    NASA Astrophysics Data System (ADS)

    Drewnick, F.; Diesch, J.-M.; Faber, P.; Borrmann, S.

    2015-04-01

    The Aerodyne Aerosol Mass Spectrometer (AMS) is a frequently used instrument for on-line measurement of the ambient sub-micron aerosol composition. With the help of calibrations and a number of assumptions on the flash vaporization and electron impact ionization processes this instrument provides robust quantitative information on various ambient aerosol components. However, when measuring close to certain anthropogenic sources or in marine environments, several of these assumptions may not be met and measurement results might easily be misinterpreted. Here we discuss various aspects of the interaction of aerosol particles with the AMS tungsten vaporizer and the consequences for the measurement results: semi-refractory components, i.e. components that vaporize but do not flash vaporize at the vaporizer and ionizer temperatures, like metal halides (e.g. chlorides, bromides or iodides of Al, Ba, Cd, Cu, Fe, Hg, K, Na, Pb, Sr, Zn) can be measured semi-quantitatively despite their relatively slow vaporization from the vaporizer. Even though non-refractory components (e.g. NH4NO3 or (NH4)2SO4) vaporize quickly, their differences in vaporization kinetics can result in undesired biases in ion collection efficiency in the measurements. Chemical reactions with water vapor and oxygen from the aerosol flow can have an influence on the mass spectra for certain components (e.g. NH4NO3, (NH4)2SO4, organic species). Finally, chemical reactions of the aerosol with the vaporizer surface can result in additional signals in the mass spectra (e.g. WO2C2-related signals from particulate Cl) and in conditioning or contamination of the vaporizer with potential memory effects influencing the mass spectra of subsequent measurements. Laboratory experiments that investigate these particle-vaporizer interactions are presented and are discussed together with field results showing that measurements of typical continental or urban aerosols are not significantly affected while laboratory

  5. Investigate the relationship between multiwavelength lidar ratios and aerosol size distributions using aerodynamic particle sizer spectrometer

    NASA Astrophysics Data System (ADS)

    Zhao, Hu; Hua, Dengxin; Mao, Jiandong; Zhou, Chunyan

    2017-02-01

    The real aerosol size distributions were obtained by aerodynamic particle sizer spectrometer (APS) in China YinChuan. The lidar ratios at wavelengths of 355 nm, 532 nm and 1064 nm were calculated using Mie theory. The effective radius of aerosol particles reff and volume C/F ratio (coarse/fine) Vc/f were retrieved from the real aerosol size distributions. The relationship between multiwavelength lidar ratios and particle reff and Vc/f were investigated. The results indicate that the lidar ratio is positive correlated to the particle reff and Vc/f. The lidar ratio is more sensitive to the coarse particles. The short wavelength lidar ratio is more sensitive to the particle Vc/f and the long wavelength lidar ratio is more sensitive to the particle reff. The wavelength dependency indicated that the lidar ratios decrease with increasing the wavelength. The lidar ratios are almost irrelevant to the shape and total particles of aerosol size distributions.

  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. An investigation into particle shape effects on the light scattering properties of mineral dust aerosol

    NASA Astrophysics Data System (ADS)

    Meland, Brian Steven

    Mineral dust aerosol plays an important role in determining the physical and chemical equilibrium of the atmosphere. The radiative balance of the Earth's atmosphere can be affected by mineral dust through both direct and indirect means. Mineral dust can directly scatter or absorb incoming visible solar radiation and outgoing terrestrial IR radiation. Dust particles can also serve as cloud condensation nuclei, thereby increasing albedo, or provide sites for heterogeneous reactions with trace gas species, which are indirect effects. Unfortunately, many of these processes are poorly understood due to incomplete knowledge of the physical and chemical characteristics of the particles including dust concentration and global distribution, as well as aerosol composition, mixing state, and size and shape distributions. Much of the information about mineral dust aerosol loading and spatial distribution is obtained from remote sensing measurements which often rely on measuring the scattering or absorption of light from these particles and are thus subject to errors arising from an incomplete understanding of the scattering processes. The light scattering properties of several key mineral components of atmospheric dust have been measured at three different wavelengths in the visible. In addition, measurements of the scattering were performed for several authentic mineral dust aerosols, including Saharan sand, diatomaceous earth, Iowa loess soil, and palagonite. These samples include particles that are highly irregular in shape. Using known optical constants along with measured size distributions, simulations of the light scattering process were performed using both Mie and T-Matrix theories. Particle shapes were approximated as a distribution of spheroids for the T-Matrix calculations. It was found that the theoretical model simulations differed markedly from experimental measurements of the light scattering, particularly near the mid-range and near backscattering angles. In

  9. Systematic Relationships Between Lidar Observables and Sizes And Mineral Composition Of Dust Aerosols

    NASA Technical Reports Server (NTRS)

    Van Diedenhoven, Bastiaan; Stangl, Alexander; Perlwitz, Jan; Fridlind, Ann M.; Chowdhary, Jacek; Cairns, Brian

    2015-01-01

    The physical and chemical properties of soil dust aerosol particles fundamentally affect their interaction with climate, including shortwave absorption and radiative forcing, nucleation of cloud droplets and ice crystals, heterogeneous formation of sulfates and nitrates on the surface of dust particles, and atmospheric processing of iron into bioavailable forms that increase the productivity of marine phytoplankton. Lidar measurements, such as extinction-to-backscatter, color and depolarization ratios, are frequently used to distinguish between aerosol types with different physical and chemical properties. The chemical composition of aerosol particles determines their complex refractive index, hence affecting their backscattering properties. Here we present a study on how dust aerosol backscattering and depolarization properties at wavelengths of 355, 532 and 1064 nm are related to size and complex refractive index, which varies with the mineral composition of the dust. Dust aerosols are represented by collections of spheroids with a range of prolate and oblate aspect ratios and their optical properties are obtained using T-matrix calculations. We find simple, systematic relationships between lidar observables and the dust size and complex refractive index that may aid the use of space-based or airborne lidars for direct retrieval of dust properties or for the evaluation of chemical transport models using forward simulated lidar variables. In addition, we present first results on the spatial variation of forward-simulated lidar variables based on a dust model that accounts for the atmospheric cycle of eight different mineral types plus internal mixtures of seven mineral types with iron oxides, which was recently implemented in the NASA GISS Earth System ModelE2.

  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. Composition of energetic particles from solar flares.

    PubMed

    Garrard, T L; Stone, E C

    1994-10-01

    We present a model for composition of heavy ions in the solar energetic particles (SEP). The SEP composition in a typical large solar particle event reflects the composition of the Sun, with adjustments due to fractionation effects which depend on the first ionization potential (FIP) of the ion and on the ratio of ionic charge to mass (Q/M). Flare-to-flare variations in composition are represented by parameters describing these fractionation effects and the distributions of these parameters are presented.

  12. CCN frequency distributions and aerosol chemical composition from long-term observations at European ACTRIS supersites

    NASA Astrophysics Data System (ADS)

    Decesari, Stefano; Rinaldi, Matteo; Schmale, Julia Yvonne; Gysel, Martin; Fröhlich, Roman; Poulain, Laurent; Henning, Silvia; Stratmann, Frank; Facchini, Maria Cristina

    2016-04-01

    Cloud droplet number concentration is regulated by the availability of aerosol acting as cloud condensation nuclei (CCN). Predicting the air concentrations of CCN involves knowledge of all physical and chemical processes that contribute to shape the particle size distribution and determine aerosol hygroscopicity. The relevance of specific atmospheric processes (e.g., nucleation, coagulation, condensation of secondary organic and inorganic aerosol, etc.) is time- and site-dependent, therefore the availability of long-term, time-resolved aerosol observations at locations representative of diverse environments is strategic for the validation of state-of-the-art chemical transport models suited to predict CCN concentrations. We focused on long-term (year-long) datasets of CCN and of aerosol composition data including black carbon, and inorganic as well as organic compounds from the Aerosol Chemical Speciation Monitor (ACSM) at selected ACTRIS supersites (http://www.actris.eu/). We discuss here the joint frequency distribution of CCN levels and of aerosol chemical components concentrations for two stations: an alpine site (Jungfraujoch, CH) and a central European rural site (Melpitz, DE). The CCN frequency distributions at Jungfraujoch are broad and generally correlated with the distributions of the concentrations of aerosol chemical components (e.g., high CCN concentrations are most frequently found for high organic matter or black carbon concentrations, and vice versa), which can be explained as an effect of the strong seasonality in the aerosol characteristics at the mountain site. The CCN frequency distributions in Melpitz show a much weaker overlap with the distributions of BC concentrations or other chemical compounds. However, especially at high CCN concentration levels, a statistical correlation with organic matter (OM) concentration can be observed. For instance, the number of CCN (with particle diameter between 20 and 250 nm) at a supersaturation of 0.7% is

  13. The real part of the refractive indices and effective densities for chemically segregated ambient aerosols in Guangzhou measured by a single-particle aerosol mass spectrometer

    NASA Astrophysics Data System (ADS)

    Zhang, Guohua; Bi, Xinhui; Qiu, Ning; Han, Bingxue; Lin, Qinhao; Peng, Long; Chen, Duohong; Wang, Xinming; Peng, Ping'an; Sheng, Guoying; Zhou, Zhen

    2016-03-01

    Knowledge on the microphysical properties of atmospheric aerosols is essential to better evaluate their radiative forcing. This paper presents an estimate of the real part of the refractive indices (n) and effective densities (ρeff) of chemically segregated atmospheric aerosols in Guangzhou, China. Vacuum aerodynamic diameter, chemical compositions, and light-scattering intensities of individual particles were simultaneously measured by a single-particle aerosol mass spectrometer (SPAMS) during the fall of 2012. On the basis of Mie theory, n at a wavelength of 532 nm and ρeff were estimated for 17 particle types in four categories: organics (OC), elemental carbon (EC), internally mixed EC and OC (ECOC), and Metal-rich. The results indicate the presence of spherical or nearly spherical shapes for the majority of particle types, whose partial scattering cross-section versus sizes were well fitted to Mie theoretical modeling results. While sharing n in a narrow range (1.47-1.53), majority of particle types exhibited a wide range of ρeff (0.87-1.51 g cm-3). The OC group is associated with the lowest ρeff (0.87-1.07 g cm-3), and the Metal-rich group with the highest ones (1.29-1.51 g cm-3). It is noteworthy that a specific EC type exhibits a complex scattering curve versus size due to the presence of both compact and irregularly shaped particles. Overall, the results on the detailed relationship between physical and chemical properties benefits future research on the impact of aerosols on visibility and climate.

  14. 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.

  15. Experimental Protocol to Investigate Particle Aerosolization of a Product Under Abrasion and Under Environmental Weathering.

    PubMed

    Shandilya, Neeraj; Le Bihan, Olivier Louis; Bressot, Christophe; Morgeneyer, Martin

    2016-09-16

    The present article presents an experimental protocol to investigate particle aerosolization of a product under abrasion and under environmental weathering, which is a fundamental element to the approach of nanosafety-by-design of nanostructured products for their durable development. This approach is basically a preemptive one in which the focus is put on minimizing the emission of engineered nanomaterials' aerosols during the usage phase of the product's life cycle. This can be attained by altering its material properties during its design phase without compromising with any of its added benefits. In this article, an experimental protocol is presented to investigate the nanosafety-by-design of three commercial nanostructured products with respect to their mechanical solicitation and environmental weathering. The means chosen for applying the mechanical solicitation is an abrasion process and for the environmental weathering, it is an accelerated UV exposure in the presence of humidity and heat. The eventual emission of engineered nanomaterials is studied in terms of their number concentration, size distribution, morphology and chemical composition. The purpose of the protocol is to study the emission for test samples and experimental conditions which are corresponding to real life situations. It was found that the application of the mechanical stresses alone emits the engineered nanomaterials' aerosols in which the engineered nanomaterial is always embedded inside the product matrix, thus, a representative product element. In such a case, the emitted aerosols comprise of both nanoparticles as well as microparticles. But if the mechanical stresses are coupled with the environmental weathering, the experimental protocol reveals then the eventual deterioration of the product, after a certain weathering duration, may lead to the emission of the free engineered nanomaterial aerosols too.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  17. Chemical composition of atmospheric aerosols from Zhenbeitai, China, and Gosan, South Korea, during ACE-Asia

    NASA Astrophysics Data System (ADS)

    Arimoto, R.; Zhang, X. Y.; Huebert, B. J.; Kang, C. H.; Savoie, D. L.; Prospero, J. M.; Sage, S. K.; Schloesslin, C. A.; Khaing, H. M.; Oh, S. N.

    2004-10-01

    Studies were conducted as part of Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia) to characterize the major ion and elemental composition of aerosol particle samples collected at Gosan, an ACE-Asia supersite (GOS, Korea, total suspended particle or TSP samples) and at Zhenbeitai (ZBT, China, TSP and particles < 2.5 μm diameter or PM2.5 samples), a site closer to the sources for Asia dust. The concentrations of 24 elements in the ZBT PM2.5 samples were correlated with Al (an indicator of mineral dust), and the ratios of these elements to Al were similar to those in a loess certified reference material, but a second group of elements was enriched over crustal proportions most likely as a result of pollution emissions. The concentrations of various water-soluble (WS) cations (Na+, K+, Ca2+, Mg2+) also were generally well correlated with Al in both the ZBT and GOS samples, with the exception being WS K+ at ZBT, where biomass burning may have had an effect. The percentage of calcium that was soluble approached 100% at ZBT versus ˜60% at GOS, and the ratio WS Ca2+/Al also was higher at ZBT. The molar ratio of sulfate to WS Ca2+ was ˜0.1 at ZBT but increased to near unity at GOS, where the aerosol nitrate/WS Ca2+ ratio was tenfold to hundredfold higher compared with ZBT, presumably because of anthropogenic influences. The observed differences in aerosol characteristics between sites can only be explained as the end product of different source contributions combined with complex processes involving gas-particle conversion, size-dependent fractionation, and aerosol mixing.

  18. Impacts of aerosol particles on the microphysical and radiative properties of stratocumulus clouds over the Southeast Pacific ocean

    NASA Astrophysics Data System (ADS)

    Twohy, C. H.; Anderson, J. R.; Toohey, D. W.; Andrejczuk, M.; Adams, A.; Lytle, M.; George, R. C.; Wood, R.; Saide, P.; Spak, S.; Zuidema, P.; Leon, D.

    2012-08-01

    distribution of droplet residual particles and ambient aerosol particles were observed. By progressively excluding small droplets from the CVI sample, we were able to show that the larger drops, which initiate drizzle, contain the largest aerosol particles. Geometric mean diameters of droplet residual particles were larger than those of the below-cloud and above cloud distributions. However, a wide range of particle sizes can act as droplet nuclei in these stratocumulus clouds. A detailed LES microphysical model was used to show that this can occur without invoking differences in chemical composition of cloud-nucleating particles.

  19. 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.

  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. ) Composites Containing Nanoparticles and Larger Particles

    NASA Astrophysics Data System (ADS)

    Ghanaraja, S.; Nath, S. K.; Ray, S.

    2014-07-01

    The composites reinforced with nanoparticles result in improved strength and ductility while those containing coarser particles of micron size have limited ductility. The present study investigates the outcome of mechanical properties in a composite reinforced simultaneously with coarse and fine particles. High energy milling of manganese dioxide particles with excess of aluminum powder ensures that nanoparticles generated, either of MnO2 or alumina, are mostly separate and surrounded by aluminum particles. The milled powder when added to aluminum alloy melt, the excess aluminum particles will melt leaving behind separate oxide nanoparticles without significant agglomeration. Different amounts of milled powder mix have been stirred into molten aluminum alloy where nanoparticles of MnO2 react with melt to form alumina. The resulting slurry is cast into composites, which also contains coarser (nearly micron size) alumina particles formed by internal oxidation of the melt during processing. The microstructure of the composites shows good distribution of both the size categories of particles without significant clustering. The oxide particles are primarily γ-alumina in a matrix of aluminum-magnesium-manganese alloy containing some iron picked up from the stirrer. These composites fail during tensile test by ductile fracture due to debonding of coarser particles. The presence of nanoparticles along with coarser particles in a composite improves both strength and ductility considerably, presumably due to delay in debonding of coarser particles to higher stress because of reduced mismatch in extension caused by increased strain hardening in presence of nanoparticles in the matrix. The composites containing only coarser oxide particles show limited strength and ductility attributed to early debonding of particles at a relatively lower stress due to larger mismatch in extension between matrix and larger particles. Higher addition of powder mix beyond a limit, however

  3. Observations and Modeling of the Green Ocean Amazon 2014/15: Transmission Electron Microscopy Analysis of Aerosol Particles Field Campaign Report

    SciTech Connect

    Buseck, Peter

    2016-03-01

    During two Intensive Operational Periods (IOP), we collected samples at 3-hour intervals for transmission electron microscopy analysis. The resulting transmission electron microscopy images and compositions were analyzed for the samples of interest. Further analysis will be done especially for the plume of interest. We found solid spherical organic particles from rebounded samples collected with Professor Scot Martin’s group (Harvard University). Approximately 30% of the rebounded particles at 95% relative humidity were spherical organic particles. Their sources and formation process are not known, but such spherical particles could be solid and will have heterogeneous chemical reactions. We observed many organic particles that are internally mixed with inorganic elements such as potassium and nitrogen. They are either homogeneously mixed or have inorganic cores with organic aerosol coatings. Samples collected from the Manaus, Brazil, pollution plume included many nano-size soot particles mixed with organic material and sulfate. Aerosol particles from clean periods included organic aerosol particles, sulfate, sea salt, dust, and primary biogenic aerosol particles. There was more dust, primary biogenic aerosol, and tar balls in samples taken during IOP1 than those taken during IOP2. Many dust particles were found between March 2 and 3.

  4. Infrared spectroscopic study of the effect of oleic acid on the deliquescence behaviour of ammonium sulfate aerosol particles.

    PubMed

    Nájera, Juan J; Horn, Andrew B

    2009-01-21

    In order to accurately assess the impact of fatty acids on the hygroscopic properties of atmospheric aerosol particles, (NH4)2SO4 (ammonium sulfate) and oleic acid (cis-9-octadecenoic acid) were chosen to perform this study as components of the particle phase. Micron-sized (700-900 nm) particles containing (NH4)2SO4 and oleic acid were generated by nebulising aqueous solutions of (NH4)2SO4 and sodium oleate. In this study, the effect of oleic acid on the deliquescence phase transition of particles was investigated in a room temperature aerosol flow tube (AFT) system using Fourier transform infrared (FTIR) spectroscopy. Particles morphologies and their chemical compositions were also analysed using a variety of techniques, including attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDX). The deliquescence relative humidity (DRH) of the (NH4)2SO4 component, determined at 81+/-2%, was slightly lowered or not affected by the presence of different thickness of oleic acid (21 nm, 44 nm and 109 nm) present in the particles. Analyses of the results presented here are consistent with earlier studies about the possible effects of water-insoluble fatty acids coatings on the phase transitions of atmospheric aerosol particles.

  5. Temperature and burning history affect emissions of greenhouse gases and aerosol particles from tropical peatland fire

    NASA Astrophysics Data System (ADS)

    Kuwata, Mikinori; Kai, Fuu Ming; Yang, Liudongqing; Itoh, Masayuki; Gunawan, Haris; Harvey, Charles F.

    2017-01-01

    Tropical peatland burning in Asia has been intensifying over the last decades, emitting huge amounts of gas species and aerosol particles. Both laboratory and field studies have been conducted to investigate emission from peat burning, yet a significant variability in data still exists. We conducted a series of experiments to characterize the gas and particulate matter emitted during burning of a peat sample from Sumatra in Indonesia. Heating temperature of peat was found to regulate the ratio of CH4 to CO2 in emissions (ΔCH4/ΔCO2) as well as the chemical composition of particulate matter. The ΔCH4/ΔCO2 ratio was larger for higher temperatures, meaning that CH4 emission is more pronounced at these conditions. Mass spectrometric analysis of organic components indicated that aerosol particles emitted at higher temperatures had more unsaturated bonds and ring structures than that emitted from cooler fires. The result was consistently confirmed by nuclear magnetic resonance analysis. In addition, CH4 emitted by burning charcoal, which is derived from previously burned peat, was lower by at least an order of magnitude than that from fresh peat. These results highlight the importance of both fire history and heating temperature for the composition of tropical peat-fire emissions. They suggest that remote sensing technologies that map fire histories and temperatures could provide improved estimates of emissions.

  6. Particle size distribution of ambient aerosols in an industrial area.

    PubMed

    Rao, B Padma; Srivastava, A; Yasmin, F; Ray, S; Gupta, N; Chauhan, C; Rao, C V C; Wate, S R

    2012-05-01

    Aerosol samples of PM(10) and PM(2.5) were collected from 38 sampling locations in and around the industrial area. The 24 h average mass concentration of PM(10) and PM(2.5) was 137.5 and 61.5 μg/m(3) respectively during summer, 122 and 97.5 μg/m(3) respectively in winter and 70 and 54 μg/m(3) respectively during post monsoon season. The relative contribution of coarse, fine and ultrafine particle to ambient air was analyzed for its temporal and seasonal variability in an industrialized area. This paper aims to establish baseline between PM(10) and PM(2.5) mass concentration levels.

  7. Chemical and physical characteristics of aerosol particles at a remote coastal location, Mace Head, Ireland, during NAMBLEX

    NASA Astrophysics Data System (ADS)

    Coe, H.; Allan, J. D.; Alfarra, M. R.; Bower, K. N.; Flynn, M. J.; McFiggans, G. B.; Topping, D. O.; Williams, P. I.; O'Dowd, C. D.; Dall'Osto, M.; Beddows, D. C. S.; Harrison, R. M.

    2005-11-01

    Aerosol number concentrations and size distributions from 3 nm to 20 µm diameter were measured at the Mace Head Atmospheric Research Station, Co. Galway, Ireland, a coastal site on the eastern seaboard of the north Atlantic Ocean. Both on and offline size resolved aerosol composition measurements were also made using an Aerodyne Aerosol Mass Spectrometer (AMS) and ion chromatographic analysis of daily samples collected using a Micro-Orifice Uniform Deposit Impactor (MOUDI). Particle number concentrations, size distributions and AMS measurements were determined at 7 and 22 m above ground level to investigate local effects on the aerosol size distribution induced by the tidal zone. During periods of new particle formation ultrafine particle number concentrations are large and variable, however, outside these periods no variability in particle number was observed at any size, nor was the particle composition variable. Analysis of particle size distributions show that within each air mass observed particle number concentrations were very consistent. During anticyclonic periods and conditions of continental outflow Aitken and accumulation mode were enhanced by a factor of 5 compared to the marine sector, whilst coarse mode particles were enhanced during westerly conditions. Baseline marine conditions were rarely met at Mace Head during NAMBLEX and high wind speeds were observed for brief periods only. Loss rates of gaseous species to aerosol surfaces were calculated for a range of uptake coefficients. Even when the accommodation coefficient is unity, lifetimes of less than 100 s were never observed and rarely were lifetimes less than 500 s. Diffusional limitation to mass transfer is important in most conditions as the coarse mode is always significant, we calculate a minimum overestimate of 50% in the loss rate if this is neglected and so it should always be considered when calculating loss rates of gaseous species to particle surfaces. HO2 and HOI have accommodation

  8. Simultaneous Measurement of Size, Composition, Hygroscopicity, and Density of Single Ambient Particles

    NASA Astrophysics Data System (ADS)

    Zelenyuk, A.; Imre, D. G.; Han, J.; Oatis, S.

    2003-12-01

    The holly grail in aerosol climate interaction is a roadmap that takes one from emissions of aerosol and aerosol precursors through aerosol transformations, to optical and cloud effects and finally to climate impacts. A critical element on this path must be the behavior of aerosol as a function of atmospheric relative humidity, which in turn requires an understanding of the correlation between aerosol composition and hygroscopicity. For single component particles this problem is tractable and reasonably understood. But, the vast majority of particles in the real atmosphere are internal mixtures of hygroscopic salts, organic acids and or bases, long chain hydrocarbons, soot, mineral dust and the list go on. Hundreds of organic compounds with highly varying hygroscopicities can be found in single particles. It would be unrealistic to expect global climate models to include and track each of these compounds. A similar problem faces the experimental world, where measuring the size, detailed molecular composition and hygroscopicity of individual particles although, in principle possible, is impractical. Single particle mass spectroscopy can be used to classify particles as organics mixed with sulfate, for example. Or in some cases pinpoint the class of some of the organics found in the mixture. But it cannot yield a quantitative measure of relative amounts. In an attempt to address this issue we have developed the method to measure simultaneously hygroscopicity, size, and composition of individual ambient particles. However, the data from Long Island NY, where the vast majority of particles were internally mixed sulfate with organics, the correlation between composition and hygroscopicity was rather weak. This is due to the fact that single-laser single particle mass spectra cannot quantitatively measure the ratio of organics to sulfates. In contrast, we found a very clear correlation between hygroscopicity and particle density for a given class of particles. In this

  9. Molecular composition of atmospheric aerosols from Halley Bay, Antarctica, using ultra-high resolution mass spectrometry

    NASA Astrophysics Data System (ADS)

    Kourtchev, Ivan; Brough, Neil; Rincon, Angela; Jones, Anna; Kalberer, Markus

    2016-04-01

    Antarctica is one of the few pristine places to study natural processes of atmospheric aerosols and anthropogenic impacts on the clean remote atmosphere. Although stratospheric aerosol in Antarctica has now been explored in some detail because of the ozone depletion phenomenon, tropospheric aerosol particles in Antarctica remain very little studied. The main goal of this work is to identify in detail the organic chemical composition of aerosol from Halley Bay station, which is located on the Brunt Ice Shelf floating on the Weddell Sea in Antarctica. In this study we characterise the molecular composition of aerosols from three seasons (summer, autumn and winter in 2012) using ultra-high resolution mass spectrometry (UHRMS). The technique provides high accuracy and high mass resolving power that allows determining unambiguous number of organic compounds present in complex organic mixtures (Noziere et al., 2015). The molecular composition interpretation was facilitated using visualisation methods (e.g. double bond equivalent, Van Krevelen diagrams, Kendrick mass analysis, and carbon oxidation state), which allowed to identify patterns, such as differences between sampling times and atmospheric processes. The majority of the identified compounds were attributed to nitrogen and sulphur containing species which exhibited very strong seasonal trends. Relatively large fraction (up to 30% of the total number of molecules) of these species contained very low hydrogen to carbon ratios (below 1) indicating that the site is impacted by anthropogenic emissions. Influences of the meteorological parameters and air mass trajectories on the molecular composition are discussed. Nozière et al., The Molecular Identification of Organic Compounds in the Atmosphere: State of the Art and Challenges, Chem. Rev., 115, 3920-3983, 2015.

  10. Composition and physical properties of the Asian Tropopause Aerosol Layer and the North American Tropospheric Aerosol Layer

    PubMed Central

    Yu, Pengfei; Toon, Owen B; Neely, Ryan R; Martinsson, Bengt G; Brenninkmeijer, Carl A M

    2015-01-01

    Recent studies revealed layers of enhanced aerosol scattering in the upper troposphere and lower stratosphere over Asia (Asian Tropopause Aerosol Layer (ATAL)) and North America (North American Tropospheric Aerosol Layer (NATAL)). We use a sectional aerosol model (Community Aerosol and Radiation Model for Atmospheres (CARMA)) coupled with the Community Earth System Model version 1 (CESM1) to explore the composition and optical properties of these aerosol layers. The observed aerosol extinction enhancement is reproduced by CESM1/CARMA. Both model and observations indicate a strong gradient of the sulfur-to-carbon ratio from Europe to the Asia on constant pressure surfaces. We found that the ATAL is mostly composed of sulfates, surface-emitted organics, and secondary organics; the NATAL is mostly composed of sulfates and secondary organics. The model also suggests that emission increases in Asia between 2000 and 2010 led to an increase of aerosol optical depth of the ATAL by 0.002 on average which is consistent with observations. Key Points The Asian Tropopause Aerosol Layer is composed of sulfate, primary organics, and secondary organics The North American Tropospheric Aerosol Layer is mostly composed of sulfate and secondary organics Aerosol Optical Depth of Asian Tropopause Aerosol Layer increases by 0.002 from 2000 to 2010 PMID:26709320

  11. Measurements of the aerosol chemical composition and mixing state in the Po Valley using multiple spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Decesari, S.; Allan, J.; Plass-Duelmer, C.; Williams, B. J.; Paglione, M.; Facchini, M. C.; O'Dowd, C.; Harrison, R. M.; Gietl, J. K.; Coe, H.; Giulianelli, L.; Gobbi, G. P.; Lanconelli, C.; Carbone, C.; Worsnop, D.; Lambe, A. T.; Ahern, A. T.; Moretti, F.; Tagliavini, E.; Elste, T.; Gilde, S.; Zhang, Y.; Dall'Osto, M.

    2014-04-01

    The use of co-located multiple spectroscopic techniques can provide detailed information on the atmospheric processes regulating aerosol chemical composition and mixing state. So far, field campaigns heavily equipped with aerosol mass spectrometers have been carried out mainly in large conurbations and in areas directly affected by their outflow, whereas lesser efforts have been dedicated to continental areas characterized by a less dense urbanization. We present here the results obtained in San Pietro Capofiume, which is located in a sparsely inhabited sector of the Po Valley, Italy. The experiment was carried out in summer 2009 in the framework of the EUCAARI project ("European Integrated Project on Aerosol, Cloud Climate Aerosol Interaction"). For the first time in Europe, six state-of-the-art techniques were used in parallel: (1) on-line TSI aerosol time-of-flight mass spectrometer (ATOFMS), (2) on-line Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-TOF-AMS), (3) soot particle aerosol mass spectrometer (SP-AMS), (4) on-line high resolution time-of-flight mass spectrometer-thermal desorption aerosol gas chromatograph (HR-ToFMS-TAG), (5) off-line twelve-hour resolution proton nuclear magnetic resonance (H-NMR) spectroscopy, and (6) chemical ionization mass spectrometry (CIMS) for the analysis of gas-phase precursors of secondary aerosol. Data from each aerosol spectroscopic method were analysed individually following ad-hoc tools (i.e. PMF for AMS, Art-2a for ATOFMS). The results obtained from each techniques are herein presented and compared. This allows us to clearly link the modifications in aerosol chemical composition to transitions in air mass origin and meteorological regimes. Under stagnant conditions, atmospheric stratification at night and early morning hours led to the accumulation of aerosols produced by anthropogenic sources distributed over the Po Valley plain. Such aerosols include primary components such as black carbon (BC

  12. Predicting the mineral composition of dust aerosols: Insights from elemental composition measured at the Izaña Observatory

    NASA Astrophysics Data System (ADS)

    Pérez García-Pando, Carlos; Miller, Ron L.; Perlwitz, Jan P.; Rodríguez, Sergio; Prospero, Joseph M.

    2016-10-01

    Regional variations of dust mineral composition are fundamental to climate impacts but generally neglected in climate models. A challenge for models is that atlases of soil composition are derived from measurements following wet sieving, which destroys the aggregates potentially emitted from the soil. Aggregates are crucial to simulating the observed size distribution of emitted soil particles. We use an extension of brittle fragmentation theory in a global dust model to account for these aggregates. Our method reproduces the size-resolved dust concentration along with the approximately size-invariant fractional abundance of elements like Fe and Al in the decade-long aerosol record from the Izaña Observatory, off the coast of West Africa. By distinguishing between Fe in structural and free forms, we can attribute improved model behavior to aggregation of Fe and Al-rich clay particles. We also demonstrate the importance of size-resolved measurements along with elemental composition analysis to constrain models.

  13. Application of Aerosol Hygroscopicity Measured at the Atmospheric Radiation Measurement Program's Southern Great Plains Site to Examine Composition and Evolution

    NASA Technical Reports Server (NTRS)

    Gasparini, Roberto; Runjun, Li; Collins, Don R.; Ferrare, Richard A.; Brackett, Vincent G.

    2006-01-01

    A Differential Mobility Analyzer/Tandem Differential Mobility Analyzer (DMA/TDMA) was used to measure submicron aerosol size distributions, hygroscopicity, and occasionally volatility during the May 2003 Aerosol Intensive Operational Period (IOP) at the Central Facility of the Atmospheric Radiation Measurement Program's Southern Great Plains (ARM SGP) site. Hygroscopic growth factor distributions for particles at eight dry diameters ranging from 0.012 micrometers to 0.600 micrometers were measured throughout the study. For a subset of particle sizes, more detailed measurements were occasionally made in which the relative humidity or temperature to which the aerosol was exposed was varied over a wide range. These measurements, in conjunction with backtrajectory clustering, were used to infer aerosol composition and to gain insight into the processes responsible for evolution. The hygroscopic growth of both the smallest and largest particles analyzed was typically less than that of particles with dry diameters of about 0.100 micrometers. It is speculated that condensation of secondary organic aerosol on nucleation mode particles is largely responsible for the minimal hygroscopic growth observed at the smallest sizes considered. Growth factor distributions of the largest particles characterized typically contained a nonhygroscopic mode believed to be composed primarily of dust. A model was developed to characterize the hygroscopic properties of particles within a size distribution mode through analysis of the fixed size hygroscopic growth measurements. The performance of this model was quantified through comparison of the measured fixed size hygroscopic growth factor distributions with those simulated through convolution of the size-resolved concentration contributed by each of the size modes and the mode-resolved hygroscopicity. This transformation from sizeresolved hygroscopicity to mode-resolved hygroscopicity facilitated examination of changes in the hygroscopic

  14. Impact of interannual variations in aerosol particle sources on orographic precipitation over California's Central Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Creamean, J. M.; Ault, A. P.; White, A. B.; Neiman, P. J.; Ralph, F. M.; Minnis, P.; Prather, K. A.

    2015-01-01

    Aerosols that serve as cloud condensation nuclei (CCN) and ice nuclei (IN) have the potential to profoundly influence precipitation processes. Furthermore, changes in orographic precipitation have broad implications for reservoir storage and flood risks. As part of the CalWater field campaign (2009-2011), the variability and associated impacts of different aerosol sources on precipitation were investigated in the California Sierra Nevada using an aerosol time-of-flight mass spectrometer for precipitation chemistry, S-band profiling radar for precipitation classification, remote sensing measurements of cloud properties, and surface meteorological measurements. The composition of insoluble residues in precipitation samples collected at a surface site contained mostly local biomass burning and long-range transported dust and biological particles (2009), local sources of biomass burning and pollution (2010), and long-range transport from distant sources (2011). Although differences in the sources were observed from year-to-year, the most consistent source of dust and biological residues were associated with storms consisting of deep convective cloud systems with significant quantities of precipitation initiated in the ice phase. Further, biological residues were dominant (up to 40%) during storms with relatively warm cloud temperatures (up to -15 °C), supporting the important role bioparticles can play as ice nucleating particles. On the other hand, lower percentages of residues from local biomass burning and pollution were observed over the three winter seasons (on average 31 and 9%, respectively). When precipitation quantities were relatively low, these residues most likely served as CCN, forming smaller more numerous cloud droplets at the base of shallow cloud systems, and resulting in less efficient riming processes. The correlation between the source of aerosols within clouds and precipitation type and quantity will be further probed in models to understand the

  15. GNI - A System for the Impaction and Automated Optical Sizing of Giant Aerosol Particles with Emphasis on Sea Salt

    NASA Astrophysics Data System (ADS)

    Jensen, Jorgen

    2013-04-01

    Size distributions of giant aerosol particles (e.g. sea-salt particles, dry radius larger than 0.5 μm) are not well characterized in the atmosphere, yet they contribute greatly to both direct and indirect aerosol effects. Measurements are problematic for these particles because they (i) occur in low concentrations, (ii) have difficulty in passing through air inlets, (iii) there are problems in discriminating between dry and deliquesced particles, (iv) and impaction sampling requires labor intensive methods. In this study, a simple, high-volume impaction system called the Giant Nuclei Impactor (GNI), based on free-stream exposure of polycarbonate slides from aircraft is described, along with an automated optical microscope-based system for analysis of the impacted particles. The impaction slides are analyzed in a humidity-controlled box (typically 90% relative humidity) that allows for deliquescence of sea salt particles. A computer controlled optical microscope with two digital cameras is used to acquire and analyze images of the aerosol particles. Salt particles will form near-spherical cap solution drops at high relative humidity. The salt mass in each giant aerosol particle is then calculated using simple geometry and K ̈ohler theory by assuming a NaCl composition. The system has a sample volume of about 10 L/s at aircraft speeds of 105 m/s. For salt particles, the measurement range is from about 0.7 μm dry radius to tens of micrometers, with a size-bin resolution of 0.2 μm dry radius. The sizing accuracy was tested using glass beads of known size. Characterizing the uncertainties of observational data is critical for applications to atmospheric science studies. A comprehensive uncertainty analysis is performed for the airborne GNI manual impaction and automatic optical microscope system for sizing giant aerosol particles, with particular emphasis on sea-salt particles. The factors included are (i) sizing accuracy, (ii) concentration accuracy, (iii

  16. A broad supersaturation scanning (BS2) approach for rapid measurement of aerosol particle hygroscopicity and cloud condensation nuclei activity

    NASA Astrophysics Data System (ADS)

    Su, H.; Cheng, Y.; Ma, N.; Wang, Z.; Wang, X.; Pöhlker, M.; Nillius, B.; Wiedensohler, A.; Pöschl, U.

    2015-09-01

    The activation and hygroscopicity of cloud condensation nuclei (CCN) are key to understand aerosol-cloud interactions and their climate impact. It can be measured by scanning the particle size and supersaturation in CCN measurements. The scanning of supersaturation is often time-consuming and limits the temporal resolution and performance of CCN measurements. Here we present a new approach, termed broad supersaturation scanning (BS2) method, in which a range of supersaturation is simultaneously scanned reducing the time interval between different supersaturation scans. The practical applicability of the BS2 approach is demonstrated with nano-CCN measurements of laboratory-generated aerosol particles. Model simulations show that the BS2 approach is also applicable for measuring CCN activation of ambient mixed particles. Due to its fast response and technical simplicity, the BS2 approach may be well suited for long-term measurements. Since hygroscopicity is closely related to the fraction of organics/inorganics in aerosol particles, a BS2-CCN counter can also serve as a complementary sensor for fast detection/estimation of aerosol chemical compositions.

  17. A broad supersaturation scanning (BS2) approach for rapid measurement of aerosol particle hygroscopicity and cloud condensation nuclei activity

    NASA Astrophysics Data System (ADS)

    Su, Hang; Cheng, Yafang; Ma, Nan; Wang, Zhibin; Wang, Xiaoxiang; Pöhlker, Mira L.; Nillius, Björn; Wiedensohler, Alfred; Pöschl, Ulrich

    2016-10-01

    The activation and hygroscopicity of cloud condensation nuclei (CCN) are key to the understanding of aerosol-cloud interactions and their impact on climate. They can be measured by scanning the particle size and supersaturation in CCN measurements. The scanning of supersaturation is often time-consuming and limits the temporal resolution and performance of CCN measurements. Here we present a new approach, termed the broad supersaturation scanning (BS2) method, in which a range of supersaturation is simultaneously scanned, reducing the time interval between different supersaturation scans. The practical applicability of the BS2 approach is demonstrated with nano-CCN measurements of laboratory-generated aerosol particles. Model simulations show that the BS2 approach may also be applicable for measuring CCN activation of ambient mixed particles. Due to its fast response and technical simplicity, the BS2 approach may be well suited for aircraft and long-term measurements. Since hygroscopicity is closely related to the fraction of organics/inorganics in aerosol particles, a BS2-CCN counter can also serve as a complementary sensor for fast detection/estimation of aerosol chemical compositions.

  18. 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.

  19. Optical properties of salt particles of a sea aerosol (laboratory experiment)

    NASA Astrophysics Data System (ADS)

    Gubareva, T. V.

    2002-02-01

    The scientific clause is devoted to complex examinations of optical properties of micro crystals of alkali-halides simulative an atmospheric salt aerosol. In laboratory requirements the interactions in system 'micro crystals of salts - gas phase' were explored at superimposition of high- energy fields. Thus the scale of radiation and cold air plasma was utilized ultraviolet, X-ray. Is shown, that the presence of high-energy fields gives in interaction of micro crystals and gas phase. At interaction the chemical composition, structure and optical properties of salt particles changes. The scientific clause is devoted to study of optical properties of salt particles mainly in infrared range of a spectrum. The purpose of operation is the study of transformation of salt micro crystals and its communications with optical parameters.

  20. Soot Aerosol Particles as Cloud Condensation Nuclei: from Ice Nucleation Activity to Ice Crystal Morphology

    NASA Astrophysics Data System (ADS)

    Pirim, Claire; Ikhenazene, Raouf; Ortega, Isamel Kenneth; Carpentier, Yvain; Focsa, Cristian; Chazallon, Bertrand; Ouf, François-Xavier

    2016-04-01

    Emissions of solid-state particles (soot) from engine exhausts due to incomplete fuel combustion is considered to influence ice and liquid water cloud droplet activation [1]. The activity of these aerosols would originate from their ability to be important centers of ice-particle nucleation, as they would promote ice formation above water homogeneous freezing point. Soot particles are reported to be generally worse ice nuclei than mineral dust because they activate nucleation at higher ice-supersaturations for deposition nucleation and at lower temperatures for immersion freezing than ratios usually expected for homogeneous nucleation [2]. In fact, there are still numerous opened questions as to whether and how soot's physico-chemical properties (structure, morphology and chemical composition) can influence their nucleation ability. Therefore, systematic investigations of soot aerosol nucleation activity via one specific nucleation mode, here deposition nucleation, combined with thorough structural and compositional analyzes are needed in order to establish any association between the particles' activity and their physico-chemical properties. In addition, since the morphology of the ice crystals can influence their radiative properties [3], we investigated their morphology as they grow over both soot and pristine substrates at different temperatures and humidity ratios. In the present work, Combustion Aerosol STandart soot samples were produced from propane using various experimental conditions. Their nucleation activity was studied in deposition mode (from water vapor), and monitored using a temperature-controlled reactor in which the sample's relative humidity is precisely measured with a cryo-hygrometer. Formation of water/ice onto the particles is followed both optically and spectroscopically, using a microscope coupled to a Raman spectrometer. Vibrational signatures of hydroxyls (O-H) emerge when the particle becomes hydrated and are used to characterize ice

  1. Sources and elemental composition of summer aerosols in the Larsemann Hills (Antarctica).

    PubMed

    Budhavant, Krishnakant; Safai, P D; Rao, P S P

    2015-02-01

    Atmospheric aerosols play a major role in the global climate change. A better physical characterization of the chemical composition of atmospheric aerosols, especially in remote atmosphere, is an important step to reduce the current uncertainty in their effect on the radiative forcing of the climate. In the present work, surface aerosols have been studied over the Southern Ocean and over Bharati, Indian Research Station at Larsemann Hills at the Antarctic coast during the summer season of 2009-2010. Aerosol samples were collected using optical particle counter (OPC) and high-volume air sampler. PM10 and PM2.5 aerosol samples were analyzed for various water-soluble and acid-soluble ionic constituents. The Hysplit model was used to compute the history of the air masses for their possible origin. Supplementary measurements of meteorological parameters were also used. The average mass concentration for PM10 over the Southern Ocean was found to be 13.4 μg m(3). Over coastal Antarctica, the mass of PM10 was 5.13 μg m(-3), whereas that of PM2.5 was 4.3 μg m(-3). Contribution of marine components, i.e., Na, Cl and Mg was dominant over the Southern Ocean (79 %) than over the coastal Antarctica where they were dominant in coarse mode (67 %) than in fine mode (53 %) aerosols. The NH4/nss-SO4 ratio of 1.12 in PM2.5 indicates that the NH4 and SO4 ions were in the form of NH4HSO4. Computation of enrichment factors indicate that elements of anthropogenic origin, e.g., Zn, Cu, Pb, etc., were highly enriched with respect to crustal composition.

  2. Measurements of the absorption and scattering coefficients of aerosol particles in suburb of Nanjing (China)

    NASA Astrophysics Data System (ADS)

    Yin, Yan; Chen, Yu; Wang, Weiwei; Yan, Jiade; Qian, Ling; Tong, Yaoqing; Lin, Zhenyi

    2008-08-01

    The absorption and scattering coefficients of atmospheric aerosols were continuously measured with a Photoacoustic Soot Spectrometer (PASS, DMT Inc. USA) at a suburb site of Nanjing, one of the regions experiencing rapid industrialization in China. The measurements were carried out during autumn and winter 2007. A preliminary analysis of the data shows that, the scattering coefficient, Bscat, is two to ten times larger than the absorption coefficient, Babs, implying that the aerosols formed/emitted in this area are more scattering than previous assumed, and can be more important in cooling the Earth-atmosphere system. The results also indicate that the absolute values of both parameters are very much dependent on the meteorological conditions, such as wind speed and direction, fog, rain, etc. as well as the time of the day. Higher values often appear at nighttimes when wind is weak, especially when a temperature inverse layer is present near the surface. Higher values of Bscat and Babs were also observed under hazy and foggy weather conditions or when wind is blown from east, where a large industrial zone is located. Simultaneous measurements of the number concentrations, chemical compositions, and size distributions of aerosol particles are used to explain the characteristics of the changes in Bscat and Babs.

  3. Massive-scale aircraft observations of giant sea-salt aerosol particle size distributions in atmospheric marine boundary layers

    NASA Astrophysics Data System (ADS)

    Jensen, J. B.

    2015-12-01

    iant sea-salt aerosol particles (dry radius, rd > 0.5 μm) occur nearly everywhere in the marine boundary layer and frequently above. This study presents observations of atmospheric sea-salt size distributions in the range 0.7 < rd < 14 μm based on external impaction of sea-spray aerosol particles onto microscope polycarbonate microscope slides. The slides have very large sample volumes, typically about 250 L over a 10-second sampling period. This provides unprecedented sampling of giant sea-salt particles for flights in marine boundary layer air. The slides were subsequently analyzed in a humidified chamber using dual optical digital microscopy. At a relative humidity of 90% the sea-salt aerosol particles form spherical cap drops. Based on measurement the volume of the spherical cap drop and assuming NaCl composition, the Kohler equation is used to derive the dry salt mass of tens of thousands of individual aerosol particles on each slide. Size distributions are given with a 0.2 μm resolution. The slides were exposed from the NSF/NCAR C-130 research aircraft during the 2008 VOCALS project off the coast of northern Chile and the 2011 ICE-T in the Caribbean. In each deployment, size distributions using hundreds of slides are used to relate fitted log-normal size distributions parameters to wind speed, altitude and other atmospheric conditions. The size distributions provide a unique observational set for initializing cloud models with coarse-mode aerosol particle observations for marine atmospheres.

  4. Hygrosopicity measurements of aerosol particles in the San Joaquin Valley, CA, Baltimore, MD, and Golden, CO

    NASA Astrophysics Data System (ADS)

    Orozco, Daniel; Beyersdorf, A. J.; Ziemba, L. D.; Berkoff, T.; Zhang, Q.; Delgado, R.; Hennigan, C. J.; Thornhill, K. L.; Young, D. E.; Parworth, C.; Kim, H.; Hoff, R. M.

    2016-06-01

    Aerosol hygroscopicity was investigated using a novel dryer-humidifier system, coupled to a TSI-3563 nephelometer, to obtain the light scattering coefficient (σscat) as a function of relative humidity (RH) in hydration and dehydration modes. The measurements were performed in Porterville, CA (10 January to 6 February 2013), Baltimore, MD (3-30 July 2013), and Golden, CO (12 July to 10 August 2014). Observations in Porterville and Golden were part of the NASA-sponsored Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality project. The measured σscat under varying RH in the three sites was combined with ground aerosol extinction, PM2.5 mass concentrations, and particle composition measurements and compared with airborne observations performed during campaigns. The enhancement factor, f(RH), defined as the ratio of σscat(RH) at a certain RH divided by σscat at a dry value, was used to evaluate the aerosol hygroscopicity. Particles in Porterville showed low average f(RH = 80%) (1.42) which was attributed to the high carbonaceous loading in the region where residential biomass burning and traffic emissions contribute heavily to air pollution. In Baltimore, the high average f(RH = 80%) (2.06) was attributed to the large contribution of SO42- in the region. The lowest water uptake was observed in Golden, with an average f(RH = 80%) = 1.24 where organic carbon dominated the particle loading. Different empirical fits were evaluated using the f(RH) data. The widely used Kasten (gamma) model was found least satisfactory, as it overestimates f(RH) for RH < 75%. A better empirical fit with two power law curve fitting parameters c and k was found to replicate f(RH) accurately from the three sites. The relationship between the organic carbon mass and the species that are affected by RH and f(RH) was also studied and categorized.

  5. Effects of Hydrodynamic Interaction in Aerosol Particle Settling: Mesoscopic Particle-level Full Dynamics Simulations

    NASA Astrophysics Data System (ADS)

    Li, Shuiqing; Yang, Mengmeng; Marshall, Jeffrey

    2014-11-01

    A new mesoscopic particle-level approach is developed for the full dynamics simulation (FDS) of the settling of systems of aerosol micro-particles. The approach efficiently combines an adhesive discrete-element method for particle motions and an Oseen dynamics method for hydrodynamic interactions. Compared to conventional Stokeslet and Oseenlet simulations, the FDS not only accounts for the cloud-scale fluid inertia effect and the particle inertia effect, but also overcomes the singularity problem using a soft-sphere model of adhesive contact. The effect of hydrodynamic interactions is investigated based on FDS results. The particle inertia is found to reduce the mobility of particle clouds and to elongate the cloud on vertical direction. Meanwhile, the fluid inertia decreases the settling velocity by weakening the hydrodynamic interaction and tends to flatten the cloud, leading to breakup. Expressions for the settling velocity of particle cloud are proposed with consideration of fluid inertia effect and the cloud shape. Finally, the transformation in settling behavior from a finite particle cloud to an unbounded uniform suspension is explained. This work has been funded by the National Natural Science Funds of China (No. 50976058), and by the National Key Basic Research and Development Program (2013CB228506).

  6. A recirculation aerosol wind tunnel for evaluating aerosol samplers and measuring particle penetration through protective clothing materials.

    PubMed

    Jaques, Peter A; Hsiao, Ta-Chih; Gao, Pengfei

    2011-08-01

    A recirculation aerosol wind tunnel was designed to maintain a uniform airflow and stable aerosol size distribution for evaluating aerosol sampler performance and determining particle penetration through protective clothing materials. The oval-shaped wind tunnel was designed to be small enough to fit onto a lab bench, have optimized dimensions for uniformity in wind speed and particle size distributions, sufficient mixing for even distribution of particles, and minimum particle losses. Performance evaluation demonstrates a relatively high level of spatial uniformity, with a coefficient of variation of 1.5-6.2% for wind velocities between 0.4 and 2.8 m s(-1) and, in this range, 0.8-8.5% for particles between 50 and 450 nm. Aerosol concentration stabilized within the first 5-20 min with, approximately, a count median diameter of 135 nm and geometric standard deviation of 2.20. Negligible agglomerate growth and particle loss are suggested. The recirculation design appears to result in unique features as needed for our research.

  7. 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...

  8. Inference of stratospheric aerosol composition and size distribution from SAGE II satellite measurements

    NASA Technical Reports Server (NTRS)

    Wang, Pi-Huan; Mccormick, M. P.; Fuller, W. H.; Yue, G. K.; Swissler, T. J.; Osborn, M. T.

    1989-01-01

    A method for inferring stratospheric aerosol composition and size distribution from the water vapor concentration and aerosol extinction measurements obtained in the Stratospheric Aerosol and Gas Experiment (SAGE) II and the associated temperature from the NMC. The aerosols are assumed to be sulfuric acid-water droplets. A modified Levenberg-Marquardt algorithm is used to determine model size distribution parameters based on the SAGE II multiwavelength aerosol extinctions. It is found that the best aerosol size information is contained in the aerosol radius range between about 0.25 and 0.80 micron.

  9. Effect of SO2 and Photolysis on Photooxidized Diesel Fuel Secondary Organic Aerosol Composition

    NASA Astrophysics Data System (ADS)

    MacMillan, A. C.; Blair, S. L.; Lin, P.; Laskin, A.; Laskin, J.; Nizkorodov, S.

    2014-12-01

    Diesel fuel (DSL) and sulfur dioxide (SO2) are important precursors to secondary organic aerosol (SOA) formation. DSL is often co-emitted with SO2 and NO2, thus it is important to understand the possible effects of SO2 on DSL SOA composition. Additionally, DSL SOA composition can be affected by photochemical aging processes such as photolysis. In this study, DSL SOA was first prepared under dry, high-NOx conditions with various concentrations of SO2 by photooxidation in a smog chamber. The SOA was then stripped of excess oxidants and gaseous organics with a denuder train and the resulting particles were photolyzed at various photolysis times in a quartz flow tube. The SOA composition, photochemical aging, properties, and mass concentration, before and after direct photolysis in the flow tube, were examined using several techniques. High-resolution mass spectrometry (HR-MS) was performed on DSL SOA samples to investigate the effect of SO2 on molecular level composition. SOA composition as a function of photolysis time was measured with an aerosol mass spectrometer (AMS). HR-MS results show that organosulfates are produced in DSL SOA. Both AMS and HR-MS results show that photolysis also has an effect on composition; though, this is more apparent in the HR-MS results than in the AMS results. In summary, both the presence of SO2 and solar radiation has an effect on DSL SOA composition.

  10. Aerosols near by a coal fired thermal power plant: chemical composition and toxic evaluation.

    PubMed

    Jayasekher, T

    2009-06-01

    Industrial processes discharge fine particulates containing organic as well as inorganic compounds into the atmosphere which are known to induce damage to cell and DNA, both in vitro and in vivo. Source and area specific studies with respect to the chemical composition, size and shape of the particles, and toxicity evaluations are very much limited. This study aims to investigate the trace elements associated with the aerosol particles distributed near to a coal burning thermal power plant and to evaluate their toxicity through Comet assay. PM(10) (particles determined by mass passing an inlet with a 50% cut-off efficiency having a 10-microm aerodynamic diameter) samples were collected using respirable dust samplers. Twelve elements (Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb, Se, Hg, and As) were analyzed using ICP-AES. Comet assay was done with the extracts of aerosols in phosphate buffered saline (PBS). Results show that Fe and Zn were found to be the predominant elements along with traces of other analyzed elements. Spherical shaped ultrafine particles of <1 microm aerodynamic diameter were detected through scanning electron microscope. PM(10) particles near to the coal burning power plant produced comets indicating their potential to induce DNA damage. DNA damage property is found to be depending upon the chemical characteristics of the components associated with the particles besides the physical properties such as size and shape.

  11. Characteristics and composition of atmospheric aerosols in Phimai, central Thailand during BASE-ASIA

    NASA Astrophysics Data System (ADS)

    Li, Can; Tsay, Si-Chee; Hsu, N. Christina; Kim, Jin Young; Howell, Steven G.; Huebert, Barry J.; Ji, Qiang; Jeong, Myeong-Jae; Wang, Sheng-Hsiang; Hansell, Richard A.; Bell, Shaun W.

    2013-10-01

    Comprehensive measurements of atmospheric aerosols were made in Phimai, central Thailand (15.183°N, 102.565°E, elevation: 206 m) during the BASE-ASIA field experiment from late February to early May in 2006. The observed aerosol loading was sizable for this rural site (mean aerosol scattering: 108 ± 64 Mm-1; absorption: 15 ± 8 Mm-1; PM10 concentration: 33 ± 17 μg m-3), and dominated by submicron particles. Major aerosol compounds included carbonaceous (OC: 9.5 ± 3.6 μg m-3; EC: 2.0 ± 2.3 μg m-3) and secondary species (SO42-: 6.4 ± 3.7 μg m-3, NH4+: 2.2 ± 1.3 μg m-3). While the site was seldom under the direct influence of large forest fires to its north, agricultural fires were ubiquitous during the experiment, as suggested by the substantial concentration of K+ (0.56 ± 0.33 μg m-3). Besides biomass burning, aerosols in Phimai during the experiment were also strongly influenced by industrial and vehicular emissions from the Bangkok metropolitan region and long-range transport from southern China. High humidity played an important role in determining the aerosol composition and properties in the region. Sulfate was primarily formed via aqueous phase reactions, and hygroscopic growth could enhance the aerosol light scattering by up to 60%, at the typical morning RH level of 85%. The aerosol single scattering albedo demonstrated distinct diurnal variation, ranging from 0.86 ± 0.04 in the evening to 0.92 ± 0.02 in the morning. This experiment marks the first time such comprehensive characterization of aerosols was made for rural central Thailand. Our results indicate that aerosol pollution has developed into a regional problem for northern Indochina, and may become more severe as the region's population and economy continue to grow.

  12. Chemical composition of the atmospheric aerosol in the troposphere over the Hudson Bay lowlands and Quebec-Labrador regions of Canada

    NASA Astrophysics Data System (ADS)

    Gorzelska, K.; Talbot, R. W.; Klemm, K.; Lefer, B.; Klemm, O.; Gregory, G. L.; Anderson, B.; Barrie, L. A.

    1994-01-01

    Atmospheric aerosols were collected in the boundary layer and free troposphere over continental and coastal subarctic regions of Canada during the July-August 1990 joint U.S.-Canadian Arctic Boundary Layer Expedition (ABLE) SB/Northern Wetlands Study (NOWES). The samples were analyzed for the following water soluble species: sulfate, nitrate, ammonium, potassium, sodium, chloride, oxalate, methylsulfonate, and total amine nitrogen. Ammonium and sulfate were the major water soluble components of these aerosols. The nearly neutral (overall) chemical composition of summertime aerosol particles contrasts their strongly acidic wintertime composition. Aerosol samples were separated into several air mass categories and characterized in terms of chemical composition, associated mixing ratios of gaseous compounds, and meteorological parameters. The fundamental category represented particles associated with"background"air masses. The summertime atmospheric aerosols in background air over the North American subarctic and Arctic regions were characterized by relatively small and spatially uniform mixing ratios of the measured species. These aerosol particles were aged to the extent that they had lost their primary source signature. The chemical profile of the background air aerosols was frequently modified by additions from biomass fire plumes, aged tropical marine air, and intrusions of upper tropospheric/lower stratospheric air. Aerosols in boundary layer background air over the boreal forested region of Quebec-Labrador had significantly larger mixing ratios of ammonium and sulfate relative to the Hudson Bay region. This may reflect infiltration of anthropogenic pollution or be due to natural emissions from this region.

  13. Chemical composition of the atmospheric aerosol in the troposphere over the Hudson Bay lowlands and Quebec-Labrador regions of Canada

    NASA Technical Reports Server (NTRS)

    Gorzelska, K.; Talbot, R. W.; Klemm, K.; Lefer, B.; Klemm, O.; Gregory, G. L.; Anderson, B.; Barrie, L. A.

    1994-01-01

    Atmospheric aerosols were collected in the boundary layer and free troposphere over continental and coastal subarctic regions of Canada during the July - August 1990 joint U.S.-Canadian Arctic Boundary Layer Expedition (ABLE) 3B/Northern Wetlands Study (NOWES). The samples were analyzed for the following water soluble species: sulfate, nitrate, ammonium, potassium, sodium, chloride, oxalate, methylsulfonate, and total amine nitrogen. Ammonium and sulfate were the major water soluble components of these aerosols. The nearly neutral (overall) chemical composition of summertime aerosol particles contrasts their strongly acidic wintertime composition. Aerosol samples were separated into several air mass categories and characterized in terms of chemical composition, associated mixing ratios of gaseous compounds, and meteorological parameters. The fundamental category represented particles associated with 'background' air masses. The summertime atmospheric aerosols in background air over the North American subarctic and Arctic regions were characterized by relatively small and spatially uniform mixing ratios of the measured species. These aerosol particles were aged to the extent that they had lost their primary source signature. The chemical profile of the background air aerosols was frequently modified by additions from biomass fire plumes, aged tropical marine air, and intrusions of upper tropospheric/lower stratospheric air. Aerosols in boundary layer background air over the boreal forest region of Quebec-Labrador had significantly larger mixing ratios of ammonium and sulfate relative to the Hudson Bay region. This may reflect infiltration of anthropogenic pollution or be due to natural emissions from this region.

  14. Quantifying the Relationship between Organic Aerosol Composition and Hygroscopicity/CCN Activity

    SciTech Connect

    Ziemann, Paul J.; Kreidenweis, Sonia M.; Petters, Markus D.

    2013-06-30

    The overall objective for this project was to provide the data and underlying process level understanding necessary to facilitate the dynamic treatment of organic aerosol CCN activity in future climate models. The specific objectives were as follows: (1) employ novel approaches to link organic aerosol composition and CCN activity, (2) evaluate the effects of temperature and relative humidity on organic aerosol CCN activity, and (3) develop parameterizations to link organic aerosol composition and CCN activity.

  15. 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.

  16. X-Ray Microspectroscopic Investigations of Remote Aerosol Composition and Changes in Aerosol Microstructure and Phase State upon Hydration

    NASA Astrophysics Data System (ADS)

    Andreae, M. O.; Artaxo, P.; Bechtel, M.; Förster, J. D.; Kilcoyne, A. L. D.; Krüger, M. L.; Pöhlker, C.; Saturno, J.; Weigand, M.; Wiedemann, K. T.

    2014-12-01

    Atmospheric aerosols play a crucial role in the Earth's climate system and hydrological cycle by scattering and absorbing sunlight and affecting the formation and development of clouds and precipitation. Our research focuses on aerosols in remote regions, in order to characterize the properties and sources of natural aerosol particles and the extent of human perturbations of the aerosol burden. The phase and mixing state of atmospheric aerosols, and particularly their hygroscopic response to relative humidity (RH) variations, is a central determinant of their atmospheric life cycle and impacts. We present an investigation using X-ray microspectroscopy on submicrometer aerosols under variable RH conditions, showing in situ changes in morphology, microstructure, and phase state upon humidity cycling. We applied Scanning Transmission X-ray Microscopy with Near-Edge X-ray Absorption Fine Structure spectroscopy (STXM-NEXAFS) under variable RH conditions to standard aerosols for a validation of the experimental approach and to internally mixed aerosol particles from the Amazonian rain forest collected during periods with anthropogenic pollution. The measurements were conducted at X-ray microscopes at the synchrotron facilities Advanced Light Source (ALS) in Berkeley, USA, and BESSY II in Berlin, Germany. Upon hydration, we observed substantial and reproducible changes in microstructure of the Amazonian particles (internal mixture of secondary organic material, ammoniated sulfate, and soot), which appear as mainly driven by efflorescence and recrystallization of sulfate salts. Multiple solid and liquid phases were found to coexist, especially in intermediate humidity regimes (60-80% RH). This shows that X-ray microspectroscopy under variable RH is a valuable technique to analyze the hygroscopic response of individual ambient aerosol particles. Our initial results underline that RH changes can trigger strong particle restructuring, in agreement with previous studies on

  17. Composite of coated magnetic alloy particle

    DOEpatents

    Moorhead, Arthur J.; Kim, Hyoun-Ee

    2000-01-01

    A composite structure and method for manufacturing same, the composite structure being comprised of metal particles and an inorganic bonding media. The method comprises the steps of coating particles of a metal powder with a thin layer of an inorganic bonding media selected from the group of powders consisting of a ceramic, glass, and glass-ceramic. The particles are assembled in a cavity and heat, with or without the addition of pressure, is thereafter applied to the particles until the layer of inorganic bonding media forms a strong bond with the particles and with the layer of inorganic bonding media on adjacent particles. The resulting composite structure is strong and remains cohesive at high temperatures.

  18. Toward Quantifying the Mass-Based Hygroscopicity of Individual Submicron Atmospheric Aerosol Particles with STXM/NEXAFS and SEM/EDX

    NASA Astrophysics Data System (ADS)

    Yancey Piens, D.; Kelly, S. T.; OBrien, R. E.; Wang, B.; Petters, M. D.; Laskin, A.; Gilles, M. K.

    2014-12-01

    The hygroscopic behavior of atmospheric aerosols influences their optical and cloud-nucleation properties, and therefore affects climate. Although changes in particle size as a function of relative humidity have often been used to quantify the hygroscopic behavior of submicron aerosol particles, it has been noted that calculations of hygroscopicity based on size contain error due to particle porosity, non-ideal volume additivity and changes in surface tension. We will present a method to quantify the hygroscopic behavior of submicron aerosol particles based on changes in mass, rather than size, as a function of relative humidity. This method results from a novel experimental approach combining scanning transmission x-ray microscopy with near-edge x-ray absorption fine spectroscopy (STXM/NEXAFS), as well as scanning electron microscopy with energy dispersive x-ray spectroscopy (SEM/EDX) on the same individual particles. First, using STXM/NEXAFS, our methods are applied to aerosol particles of known composition ‒ for instance ammonium sulfate, sodium bromide and levoglucosan ‒ and validated by theory. Then, using STXM/NEXAFS and SEM/EDX, these methods are extended to mixed atmospheric aerosol particles collected in the field at the DOE Atmospheric Radiation Measurement (ARM) Climate Research Facility at the Southern Great Planes sampling site in Oklahoma, USA. We have observed and quantified a range of hygroscopic behaviors which are correlated to the composition and morphology of individual aerosol particles. These methods will have implications for parameterizing aerosol mixing state and cloud-nucleation activity in atmospheric models.

  19. Using the Relationship between MODIS Aerosol Optical Thickness and OMI Trace Gas Columns to better understand Aerosol Formation and Chemical Composition

    NASA Astrophysics Data System (ADS)

    Veefkind, Pepijn; Boersma, Folkert; Wang, Jun; Levelt, Pieternel

    2010-05-01

    Aerosols are one of the leading uncertainties in global and regional climate change. One of the most important reasons for the limited understanding of the effects of aerosols is their strong temporal and spatial variability in chemical composition and size distribution. Important anthropogenic sources for aerosols are transportation, power plants, industries and biomass burning. Natural sources include windblown desert dust, sea spray, biogenic emissions, volcanoes, and biomass burning. Together, these sources form a complex chemical mixture of desert dust, sea salt, sulfates, nitrates and organic material. To better understand the Earth's climate system, accurate knowledge is needed on the complex relation between the emissions of precursor gases and primary aerosol particles, and aerosol composition. Satellite measurements have the horizontal and temporal coverage to assess the global effect of aerosols on climate. In addition to the information on aerosols, tropospheric columns of nitrogen dioxide (NO2), formaldehyde (HCHO) and sulfur dioxide (SO2) can be observed from space. In this contribution, the spatial and temporal correlations between AOT and tropospheric columns of NO2, SO2 and HCHO are used to derive information on the composition of the aerosols particles. Spatial correlation between AOT and NO2 indicate that the aerosols are from combustion processes, such as fossil fuel and biomass burning. The AOT to NO2 ratio provides zeroth order information on the combustion sources. This ratio is low for regions dominated by controlled fossil fuel combustion and high for biomass burning regions, whereas the difference of this ratio between these regions can be more than two orders of magnitude. Overall the GEOS-CHEM simulations can reproduce the observed AOT-NO2 ratios well. Spatial correlation between AOT and NO2 is found for many of the industrialized ad biomass burning regions in the world. Correlations with HCHO are especially important in biomass burning

  20. Aerosol composition and microstructure in the smoky atmosphere of Moscow during the August 2010 extreme wildfires

    NASA Astrophysics Data System (ADS)

    Popovicheva, O. B.; Kistler, M.; Kireeva, E. D.; Persiantseva, N. M.; Timofeev, M. A.; Shoniya, N. K.; Kopeikin, V. M.

    2017-01-01

    This is a comprehensive study of the physicochemical characterization of multicomponent aerosols in the smoky atmosphere of Moscow during the extreme wildfires of August 2010 and against the background atmosphere of August 2011. Thermal-optical analysis, liquid and ion chromatography, IR spectroscopy, and electron microscopy were used to determine the organic content (OC) and elemental content (EC) of carbon, organic/inorganic and ionic compounds, and biomass burning markers (anhydrosaccharides and the potassium ion) and study the morphology and elemental composition of individual particles. It has been shown that the fires are characterized by an increased OC/EC ratio and high concentrations of ammonium, potassium, and sulfate ions in correlation with an increased content of levoglucosan as a marker of biomass burning. The organic compounds containing carbonyl groups point to the process of photochemical aging and the formation of secondary organic aerosols in the urban atmosphere when aerosols are emitted from forest fires. A cluster analysis of individual particles has indicated that when the smokiest atmosphere is characterized by prevailing soot/tar ball particles, which are smoke-emission micromarkers.

  1. Functional Group Composition of Semivolatile Compounds Present in Submicron Organic Aerosol

    NASA Astrophysics Data System (ADS)

    Ruggeri, G.; Modini, R. L.; Iannarelli, R.; Rossi, M. J.; Takahama, S.

    2014-12-01

    Semivolatile organic compounds can partition between gas and particle phase in atmospheric conditions and can be volatilized and lost when the aerosol sampling is performed onto PTFE filters (Eatough et al., 1993). In this work, semivolatile compounds are collected onto carbon impregnated glass fiber-cellulose filters placed in series after an activated carbon denuder and PTFE filter which collects submicron aerosol particles of low volatility (Subramanian et al., 2004). The semivolatile compounds accumulated on the cellulose-glass fiber filters are desorbed by vacuum and injected into a stainless steel chamber that enables cold-trapping. The vapors in this chamber are condensed onto a low-temperature silicon window, and the composition of deposited vapors are analysed by transmission-mode Fourier Transform Infrared (FTIR) spectroscopy (Delval and Rossi, 2004). Functional group composition of semivolatile compounds that can be desorbed from the aerosol phase and its relationship with the apparent low-volatile fraction composition will be presented. Eatough, D.J., Wadsworth, A., Eatough, D.A., Crawford, J.W., Hansen, L.D., Lewis, E.A., 1993. A multiple-system, multi-channel diffusion denuder sampler for the determination of fine-particulate organic material in the atmosphere. Atmospheric Environment. Part A. General Topics 27, 1213-1219. Subramanian, R., Khlystov, A.Y., Cabada, J.C., Robinson, A.L., 2004. Positive and negative artifacts in particulate organic carbon measurements with denuded and undenuded sampler configurations. Aerosol Science and Technology 38, 27-48. Delval, C., Rossi, M.J., 2004. The kinetics of condensation and evaporation of H2O from pure ice in the range 173-223 K: a quartz crystal microbalance study. Physical Chemistry Chemical Physics 6, 4665-4676.

  2. Dust and Non-dust Aerosol Outflow from Asia by Size, Time, and Composition, Spring, and Summer, 2001

    NASA Astrophysics Data System (ADS)

    Cahill, T. A.; Cliff, S. S.; Jimenez-Cruz, M. P.; Perry, K. D.

    2002-12-01

    Asian aerosols were characterized by size, time, and composition at 9 surface sites in China, Taiwan, Korea, and Japan during ACE-Asia, Spring 2001, as well as during a smaller summer NSF program. In this report, we will characterize these aerosols by source region in Asia, by aerosol mass, size distribution, time profiles, and composition, along with their forward trajectories into the Pacific. The primary aerosol collection technique was the DELTA Group slotted 8-DRUM impactor, 0.09 to 12 micrometers diameter, while compositional analysis was done every 3 hours in each size mode by synchrotron-x-ray fluorescence analysis. Comparisons of aerosols have been generated in the individual source regions, with major and trace element signatures, greatly assisting identification of aerosols seen later in transport events. Paired surface sites at low and high elevations were operational in Korea and Japan, aiding in separating truly local from regional aerosols. These data are then compared to downwind pollution events, with source regions identified by HYSPLIT isentropic trajectories. In the period between March 20 and April 20, we observed 3 major dust storms, several minor dust events, and massive non-dust aerosol emissions leaving the Asian mainland. Dust from the Takla Makan desert was observed to differ from Gobi dust by both particle size (finer) and elemental ratio (especially calcium to silicon). Very fine silicon and selenium identified coal combustion regions, while arsenic tracked mainly smelting operations. Non-sea salt sulfate contributions were generated in 8 size modes from 0.09 to 12 micrometers diameter. Finally, these data will incorporated into aerosol transport models for comparison with downwind sites in the USA and beyond.

  3. 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.

  4. 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.

  5. 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 act