Science.gov

Sample records for aerosol chemical composition

  1. 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.

  2. 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.

  3. 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

  4. Surface submicron aerosol chemical composition: What fraction is not sulfate?

    NASA Astrophysics Data System (ADS)

    Quinn, P. K.; Bates, T. S.; Miller, T. L.; Coffman, D. J.; Johnson, J. E.; Harris, J. M.; Ogren, J. A.; Forbes, G.; Anderson, T. L.; Covert, D. S.; Rood, M. J.

    2000-03-01

    Measurements of submicron aerosol mass and the mass of major ionic components have been made over the past 5 years on cruises in the Pacific and Southern Oceans and at monitoring stations across North America (Barrow, Alaska; Cheeka Peak, Washington; Bondville, Illinois; and Sable Island, Nova Scotia). Reported here are submicron concentrations of aerosol mass, nonsea salt (nss) sulfate, sea salt, methanesulfonate, other nss inorganic ions, and residual, or chemically unanalyzed, mass. Residual mass concentrations are based on the difference between simultaneously measured aerosol mass and the mass of the major ionic components. A standardized sampling protocol was used for all measurements making the data from each location directly comparable. For the Pacific and Southern Oceans, concentrations of the chemical components are presented in zonally averaged 20° latitude bins. For the monitoring stations, mean concentrations are presented for distinct air mass types (marine, clean continental, and polluted based on air mass back trajectories). In addition, percentile information for each chemical component is given to indicate the variability in the measured concentrations. Mean nss sulfate submicron aerosol mass fractions for the different latitude bins of the Pacific ranged from 0.14±0.01 to 0.34±0.03 (arithmetic mean±absolute uncertainty at the 95% confidence level). The lowest average value occurred in the 40°-60°S latitude band where nss sulfate concentrations were low due to the remoteness from continental sources and sea salt concentrations were relatively high. Mean nss sulfate aerosol mass fractions were more variable at the monitoring stations ranging from 0.13±0.004 to 0.65±0.02. Highest values occurred in polluted air masses at Bondville and Sable Island. Sea salt mean mass fractions ranged between 0.20±0.02 and 0.53±0.03 at all latitude bands of the Pacific (except 20°-40°N where the residual mass fraction was relatively high) and at Barrow

  5. Effects of aerosol sources and chemical compositions on cloud drop sizes and glaciation temperatures

    NASA Astrophysics Data System (ADS)

    Zipori, Assaf; Rosenfeld, Daniel; Tirosh, Ofir; Teutsch, Nadya; Erel, Yigal

    2015-09-01

    The effect of aerosols on cloud properties, such as its droplet sizes and its glaciation temperatures, depends on their compositions and concentrations. In order to examine these effects, we collected rain samples in northern Israel during five winters (2008-2011 and 2013) and determined their chemical composition, which was later used to identify the aerosols' sources. By combining the chemical data with satellite-retrieved cloud properties, we linked the aerosol types, sources, and concentrations with the cloud glaciation temperatures (Tg). The presence of dust increased Tg from -26°C to -12°C already at relatively low dust concentrations. This result is in agreement with the conventional wisdom that desert dust serves as good ice nuclei (INs). With higher dust concentrations, Tg saturated at -12°C, even though cloud droplet sizes decreased as a result of the cloud condensation nucleating (CCN) activity of the dust. Marine air masses also encouraged freezing, but in this case, freezing was enhanced by the larger cloud droplet sizes in the air masses (caused by low CCN concentrations) and not by IN concentrations or by aerosol type. An increased fraction of anthropogenic aerosols in marine air masses caused a decrease in Tg, indicating that these aerosols served as poor IN. Anthropogenic aerosols reduced cloud droplet sizes, which further decreased Tg. Our results could be useful in climate models for aerosol-cloud interactions, as we investigated the effects of aerosols of different sources on cloud properties. Such parameterization can simplify these models substantially.

  6. Simulation of aerosol chemical compositions in the Western Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Chrit, Mounir; Kata Sartelet, Karine; Sciare, Jean; Marchand, Nicolas; Pey, Jorge; Sellegri, Karine

    2016-04-01

    This work aims at evaluating the chemical transport model (CTM) Polair3d of the air-quality modelling platform Polyphemus during the ChArMex summer campaigns of 2013, using ground-based measurements performed at ERSA (Cape Corsica, France), and at determining the processes controlling organic aerosol concentrations at ERSA. Simulations are compared to measurements for concentrations of both organic and inorganic species, as well as the ratio of biogenic versus anthropogenic particles, and organic aerosol properties (oxidation state). For inorganics, the concentrations of sulphate, sodium, chloride, ammonium and nitrate are compared to measurements. Non-sea-salt sulphate and ammonium concentrations are well reproduced by the model. However, because of the geographic location of the measurement station at Cape Corsica which undergoes strong wind velocities and sea effects, sea-salt sulphate, sodium, chloride and nitrate concentrations are strongly influenced by the parameterizations used for sea-salt emissions. Different parameterizations are compared and a parameterization is chosen after comparison to sodium measurements. For organics, the concentrations are well modelled when compared to experimental values. Anthropogenic particles are influenced by emission of semi-volatile organic compounds (SVOC). Measurements allow us to refine the estimation of those emissions, which are currently missing in emission inventories. Although concentrations of biogenic particles are well simulated, the organic chemical compounds are not enough oxidised in the model. The observed oxidation state of organics shows that the oligomerisation of pinonaldehyde was over-estimated in Polyphemus. To improve the oxidation property of organics, the formation of extremely low volatile organic compounds from autoxidation of monoterpenes is added to Polyphemus, using recently published data from chamber experiments. These chemical compounds are highly oxygenated and are formed rapidly, as first

  7. 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

  8. Decadal trends in aerosol chemical composition at Barrow, AK: 1976-2008

    NASA Astrophysics Data System (ADS)

    Quinn, P. K.; Bates, T. S.; Schulz, K.; Shaw, G. E.

    2009-09-01

    Aerosol measurements at Barrow, AK during the past 30 years have identified the long range transport of pollution associated with Arctic Haze as well as ocean-derived aerosols of more local origin. Here, we focus on measurements of aerosol chemical composition to assess 1) trends in Arctic Haze aerosol and implications for source regions, 2) the interaction between pollution-derived and ocean-derived aerosols and the resulting impacts on the chemistry of the Arctic boundary layer, and 3) the response of aerosols to a changing climate. Aerosol chemical composition measured at Barrow, AK during the Arctic haze season is compared for the years 1976-1977 and 1997-2008. Based on these two data sets, concentrations of non-sea salt (nss) sulfate (SO4=) and non-crustal (nc) vanadium (V) have decreased by about 60% over this 30 year period. Consistency in the ratios of nss SO4=/ncV and nc manganese (Mn)/ncV between the two data sets indicates that, although emissions have decreased in the source regions, the source regions have remained the same over this time period. The measurements from 1997-2008 indicate that, during the haze season, the nss SO4= aerosol at Barrow is becoming less neutralized by ammonium (NH4+) yielding an increasing sea salt aerosol chloride (Cl-) deficit. The expected consequence is an increase in the release of Cl atoms to the atmosphere and a change in the lifetime of volatile organic compounds (VOCs) including methane. In addition, summertime concentrations of biogenically-derived methanesulfonate (MSA-) and nss SO4= are increasing at a rate of 12 and 8% per year, respectively. Further research is required to assess the environmental factors behind the increasing concentrations of biogenic aerosol.

  9. Decadal trends in aerosol chemical composition at Barrow, Alaska: 1976-2008

    NASA Astrophysics Data System (ADS)

    Quinn, P. K.; Bates, T. S.; Schulz, K.; Shaw, G. E.

    2009-11-01

    Aerosol measurements at Barrow, Alaska during the past 30 years have identified the long range transport of pollution associated with Arctic Haze as well as ocean-derived aerosols of more local origin. Here, we focus on measurements of aerosol chemical composition to assess (1) trends in Arctic Haze aerosol and implications for source regions, (2) the interaction between pollution-derived and ocean-derived aerosols and the resulting impacts on the chemistry of the Arctic boundary layer, and (3) the response of aerosols to a changing climate. Aerosol chemical composition measured at Barrow, AK during the Arctic haze season is compared for the years 1976-1977 and 1997-2008. Based on these two data sets, concentrations of non-sea salt (nss) sulfate (SO4=) and non-crustal (nc) vanadium (V) have decreased by about 60% over this 30 year period. Consistency in the ratios of nss SO4=/ncV and nc manganese (Mn)/ncV between the two data sets indicates that, although emissions have decreased in the source regions, the source regions have remained the same over this time period. The measurements from 1997-2008 indicate that, during the haze season, the nss SO4= aerosol at Barrow is becoming less neutralized by ammonium (NH4+) yielding an increasing sea salt aerosol chloride (Cl-) deficit. The expected consequence is an increase in the release of Cl atoms to the atmosphere and a change in the lifetime of volatile organic compounds (VOCs) including methane. In addition, summertime concentrations of biogenically-derived methanesulfonate (MSA-) and nss SO4= are increasing at a rate of 12 and 8% per year, respectively. Further research is required to assess the environmental factors behind the increasing concentrations of biogenic aerosol.

  10. Chemical composition of aerosols over Bay of Bengal during pre-monsoon: Dominance of anthropogenic sources

    NASA Astrophysics Data System (ADS)

    Nair, Prabha R.; George, Susan K.; Aryasree, S.; Jacob, Salu

    2014-03-01

    Total suspended particulates were collected from the marine boundary layer of Bay of Bengal (BoB) as part of the Integrated Campaign for Aerosols gases & Radiation Budget (ICARB) conducted under the Geosphere Biosphere Programme of Indian Space Research Organisation during pre-monsoon period. These samples were analyzed to quantify various chemical species and to bring out a comprehensive and quantitative picture of the chemical composition of aerosols in the marine environment of Bay of Bengal. Almost all the species showed highest mass concentration over north/head BoB. On the other hand, their mass fractions were high over mid/south BoB which has implications on the radiative forcing in this region. The source characteristics of various species were identified using specific chemical components as tracers. Presence of significant amount of non-sea-salt aerosols (~7-8 times of sea-salt) and several trace species like Ni, Pb, Zn, etc were observed in this marine environment indicating significant continental/anthropogenic influence. An approximate estimate of the contributions of anthropogenic and natural aerosols to the total aerosol mass loading showed prominence of anthropogenic component over mid and south BoB also. Based on this study first-cut aerosol chemical models were evolved for BoB region.

  11. Atmospheric aerosols: A literature summary of their physical characteristics and chemical composition

    NASA Technical Reports Server (NTRS)

    Harris, F. S., Jr.

    1976-01-01

    This report contains a summary of 199 recent references on the characterization of atmospheric aerosols with respect to their composition, sources, size distribution, and time changes, and with particular reference to the chemical elements measured by modern techniques, especially activation analysis.

  12. 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.

  13. A model for studying the composition and chemical effects of stratospheric aerosols

    NASA Technical Reports Server (NTRS)

    Tabazadeh, Azadeh; Turco, Richard P.; Jacobson, Mark Z.

    1994-01-01

    We developed polynomial expressions for the temperature dependence of the mean binary and water activity coefficients for H2SO4 and HNO3 solutions. These activities were used in an equilibrium model to predict the composition of stratospheric aerosols under a wide range of environmental conditions. For typical concentrations of H2O, H2SO4, HNO3, HCl, HBr, HF, and HOCl in the lower stratosphere, the aerosol composition is estimated as a function of the local temperature and the ambient relative humidity. For temperatures below 200 K, our results indicate that (1) HNO3 contributes a significant mass fraction to stratospheric aerosols, and (2) HCl solubility is considerably affected by HNO3 dissolution into sulfate aerosols. We also show that, in volcanically disturbed periods, changes in stratospheric aerosol composition can significantly alter the microphysics that leads to the formation of polar stratospheric clouds. The effects caused by HNO3 dissolution on the physical and chemical properties of stratospheric aerosols are discussed.

  14. 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

  15. 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

  16. The application of thermal methods for determining chemical composition of carbonaceous aerosols: a review.

    PubMed

    Chow, Judith C; Yu, Jian Zhen; Watson, John G; Ho, Steven Sai Hang; Bohannan, Theresa L; Hays, Michael D; Fung, Kochy K

    2007-09-01

    Thermal methods of various forms have been used to quantify carbonaceous materials. Thermal/optical carbon analysis provides measurements of organic and elemental carbon concentrations as well as fractions evolving at specific temperatures in ambient and source aerosols. Detection of thermally desorbed organic compounds with thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS) identifies and quantifies over 100 individual organic compounds in particulate matter (PM) samples. The resulting mass spectra contain information that is consistent among, but different between, source emissions even in the absence of association with specific organic compounds. TD-GC/MS is a demonstrated alternative to solvent extraction for many organic compounds and can be applied to samples from existing networks. It is amenable to field-deployable instruments capable of measuring organic aerosol composition in near real-time. In this review, thermal stability of organic compounds is related to chemical structures, providing a basis for understanding thermochemical properties of carbonaceous aerosols. Recent advances in thermal methods applied to determine aerosol chemical compositions are summarized and their potential for uncovering aerosol chemistry are evaluated. Current limitations and future research needs of the thermal methods are included.

  17. 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).

  18. 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

  19. 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

  20. 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.

  1. 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

  2. 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

  3. Biomass burning aerosol over the Amazon during SAMBBA: impact of chemical composition on radiative properties

    NASA Astrophysics Data System (ADS)

    Morgan, William; Allan, James; Flynn, Michael; Darbyshire, Eoghan; Hodgson, Amy; Liu, Dantong; O'shea, Sebastian; Bauguitte, Stephane; Szpek, Kate; Langridge, Justin; Johnson, Ben; Haywood, Jim; Longo, Karla; Artaxo, Paulo; Coe, Hugh

    2014-05-01

    Biomass burning represents one of the largest sources of particulate matter to the atmosphere, resulting in a significant perturbation to the Earth's radiative balance coupled with serious impacts on public health. Globally, biomass burning aerosols are thought to exert a small warming effect but with the uncertainty being 4 times greater than the central estimate. On regional scales, the impact is substantially greater, particularly in areas such as the Amazon Basin where large, intense and frequent burning occurs on an annual basis for several months. Absorption by atmospheric aerosols is underestimated by models over South America, which points to significant uncertainties relating to Black Carbon (BC) aerosol properties. Initial results from the South American Biomass Burning Analysis (SAMBBA) field experiment, which took place during September and October 2012 over Brazil on-board the UK Facility for Airborne Atmospheric Measurement (FAAM) BAe-146 research aircraft, are presented here. Aerosol chemical composition was measured by an Aerodyne Aerosol Mass Spectrometer (AMS) and a DMT Single Particle Soot Photometer (SP2). The physical, chemical and optical properties of the aerosols across the region will be characterized in order to establish the impact of biomass burning on regional air quality, weather and climate. The aircraft sampled a range of conditions including sampling of pristine Rainforest, fresh biomass burning plumes, regional haze and elevated biomass burning layers within the free troposphere. The aircraft sampled biomass burning aerosol across the southern Amazon in the states of Rondonia and Mato Grosso, as well as in a Cerrado (Savannah-like) region in Tocantins state. This presented a range of fire conditions, both in terms of their number, intensity, vegetation-type and their combustion efficiencies. Near-source sampling of fires in Rainforest environments suggested that smouldering combustion dominated, while flaming combustion dominated

  4. 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.

  5. Aerosol Optical Properties Measured Onboard the Ronald H. Brown During ACE Asia as a Function of Aerosol Chemical Composition and Source Region

    NASA Technical Reports Server (NTRS)

    Quinn, P. K.; Coffman, D. J.; Bates, T. S.; Welton, E. J.; Covert, D. S.; Miller, T. L.; Johnson, J. E.; Maria, S.; Russell, L.; Arimoto, R.

    2004-01-01

    During the ACE Asia intensive field campaign conducted in the spring of 2001 aerosol properties were measured onboard the R/V Ronald H. Brown to study the effects of the Asian aerosol on atmospheric chemistry and climate in downwind regions. Aerosol properties measured in the marine boundary layer included chemical composition; number size distribution; and light scattering, hemispheric backscattering, and absorption coefficients. In addition, optical depth and vertical profiles of aerosol 180 deg backscatter were measured. Aerosol within the ACE Asia study region was found to be a complex mixture resulting from marine, pollution, volcanic, and dust sources. Presented here as a function of air mass source region are the mass fractions of the dominant aerosol chemical components, the fraction of the scattering measured at the surface due to each component, mass scattering efficiencies of the individual components, aerosol scattering and absorption coefficients, single scattering albedo, Angstrom exponents, optical depth, and vertical profiles of aerosol extinction. All results except aerosol optical depth and the vertical profiles of aerosol extinction are reported at a relative humidity of 55 +/- 5%. An over-determined data set was collected so that measured and calculated aerosol properties could be compared, internal consistency in the data set could be assessed, and sources of uncertainty could be identified. By taking into account non-sphericity of the dust aerosol, calculated and measured aerosol mass and scattering coefficients agreed within overall experimental uncertainties. Differences between measured and calculated aerosol absorption coefficients were not within reasonable uncertainty limits, however, and may indicate the inability of Mie theory and the assumption of internally mixed homogeneous spheres to predict absorption by the ACE Asia aerosol. Mass scattering efficiencies of non-sea salt sulfate aerosol, sea salt, submicron particulate organic

  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. Formation and aging of secondary organic aerosol from toluene: changes in chemical composition, volatility, and hygroscopicity

    DOE PAGES

    Hildebrandt Ruiz, L.; Paciga, A. L.; Cerully, K. M.; ...

    2015-07-24

    Secondary organic aerosol (SOA) is transformed after its initial formation, but this chemical aging of SOA is poorly understood. Experiments were conducted in the Carnegie Mellon environmental chamber to form secondary organic aerosol (SOA) from the photo-oxidation of toluene and other small aromatic volatile organic compounds (VOCs) in the presence of NOx under different oxidizing conditions. The effects of the oxidizing condition on organic aerosol (OA) composition, mass yield, volatility, and hygroscopicity were explored. Higher exposure to the hydroxyl radical resulted in different OA composition, average carbon oxidation state (OSc), and mass yield. The OA oxidation state generally increased duringmore » photo-oxidation, and the final OA OSc ranged from -0.29 to 0.16 in the performed experiments. The volatility of OA formed in these different experiments varied by as much as a factor of 30, demonstrating that the OA formed under different oxidizing conditions can have a significantly different saturation concentration. There was no clear correlation between hygroscopicity and oxidation state for this relatively hygroscopic SOA.« less

  8. All-year-round aerosol chemical composition at Dome C, Antarctica

    NASA Astrophysics Data System (ADS)

    Udisti, Roberto; Becagli, Silvia; Frosini, Daniele; Galli, Gaia; Ghedini, Costanza; Rugi, Francesco; Severi, Mirko; Traversi, Rita

    2010-05-01

    Since 2005, continuous, all-year-round aerosol sampling was carried out at Dome C (Central East Antarctica, 3233 m a.s.l., about 1100 km far from the coastline), in the framework of "Station Concordia" project, an Italian PNRA - French IPEV joint program. Size-segregated aerosol samples were collected in summer and winter periods by using different low- and medium-volume systems, including pre-selected cut-off samplers (with PM10, PM2.5 and PM1 cut-off heads) and multi-stage (Andersen 8-stage and Dekati 4-stage) impactors. Sampling resolution and volumes ranged from 1 day to 1 month and from 2.3 to 12 m3/h, respectively. Aerosol study at Dome C is expected improving our knowledge on present-day source intensity, transport efficiency and pathways (including stratosphere-troposphere interchanges) of particles reaching internal sites of Antarctica. Besides, more detailed information on atmosphere-snow interactions, including depositional and post-depositional processes, as well as the effect of sublimation/condensation processes on snow surface, will be used for improving the reconstruction of past atmosphere composition from ice core chemical stratigraphies (EPICA Dome C ice core). Here we report major results from the chemical composition of the Antarctic background aerosol reaching Dome C, pointing out the seasonal pattern and the temporal trend of some ionic components used as tracers of sea spray, marine biogenic and crustal emissions. Oxidised sulfur compounds are assumed to affect the climate system by influencing the Earth's radiative budget, both directly (solar light scattering) and indirectly (acting as cloud condensation nuclei). Among these compounds, methanesulphonic acid (MSA) and H2SO4 (arising from the atmospheric oxidation of phytoplanktonic dimethylsulphide - DMS), are considered the best tracers of marine productivity. Their use as reliable markers of oceanic biogenic emissions is hindered by poorly known mechanisms (temperature and photochemistry

  9. Secondary organic aerosol formation during the photooxidation of toluene: NOx dependence of chemical composition.

    PubMed

    Sato, Kei; Hatakeyama, Shiro; Imamura, Takashi

    2007-10-04

    The photooxidation of toluene is a potential source of secondary organic aerosol (SOA) in urban air, but only a small portion of the compounds present in SOA have been identified. In this study, we analyzed the chemical compositions of SOA produced by photoirradiation of the toluene/NOx/air system in laboratory chamber experiments by a combination of liquid chromatography-mass spectrometry, hybrid high-performance liquid chromatography-mass spectrometry, and iodometry-spectrophotometry. The dependence of the chemical composition on the initial NOx concentration was examined at initial NO concentrations ([NO]0) of 0.2 and 1 ppmv. Fifteen semivolatile products, including aromatic and ring-cleavage compounds, were quantified. However, the quantified products comprised only a small portion ( approximately 1 wt %) of the total aerosol mass. The total SOA yield ( approximately 13 wt %), the ratio of organic peroxides to total SOA mass ( approximately 17 wt %), and the density of SOA ( approximately 1.4 g cm-3) were independent of the NOx level, suggesting that the reaction mechanisms of the formation of major SOA products at [NO]0 = 0.2 and 1 ppmv are essentially the same. The negative-ion mass spectra of SOA samples showed that ion signals attributed to hemiacetal oligomers and/or decomposition products of peroxy hemiacetal oligomers were detected in the range of mass-to-charge ratios (m/z) between 200 and 500. The highest signals were detected at m/z = 155 and 177, and these were tentatively assigned to C7 unsaturated oxacyclic oxocarboxylic acids and C7 unsaturated oxacyclic dicarboxylic acids, respectively. We conclude that the major chemical components of the aerosol are hemiacetal and peroxy hemiacetal oligomers and low-molecular-weight dicarboxylic acids.

  10. Chemical composition, sources, and processes of urban aerosols during summertime in Northwest China: insights from High Resolution Aerosol Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Xu, J.; Zhang, Q.; Chen, M.; Ge, X.; Ren, J.; Qin, D.

    2014-06-01

    An aerodyne High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) was deployed along with a Scanning Mobility Particle Sizer (SMPS) and a Multi Angle Absorption Photometers (MAAP) to measure the temporal variations of the mass loading, chemical composition, and size distribution of sub-micrometer particulate matter (PM1) in Lanzhou, northwest China, during 12 July-7 August 2012. The average PM1 mass concentration including non-refractory PM1 (NR-PM1) measured by HR-ToF-AMS and black carbon (BC) measured by MAAP during this study was 24.5 μg m-3 (ranging from 0.86 to 105μg m-3), with a mean composition consisting of 47% organics, 16% sulfate, 12% BC, 11% ammonium, 10% nitrate, and 4% chloride. The organics was consisted of 70% carbon, 21% oxygen, 8% hydrogen, and 1% nitrogen, with the average oxygen-to-carbon ratio (O / C) of 0.33 and organic mass-to-carbon ratio (OM / OC) of 1.58. Positive matrix factorization (PMF) of the high-resolution mass spectra of organic aerosols (OA) identified four distinct factors which represent, respectively, two primary OA (POA) emission sources (traffic and food cooking) and two secondary OA (SOA) types - a fresher, semi-volatile oxygenated OA (SV-OOA) and a more aged, low-volatility oxygenated OA (LV-OOA). Traffic-related hydrocarbon-like OA (HOA) and BC displayed distinct diurnal patterns both with peak at ~07:00-11:00 (BJT: UTC +8) corresponding to the morning rush hours, while cooking OA (COA) peaked during three meal periods. The diurnal profiles of sulfate and LV-OOA displayed a broad peak between ∼07:00-15:00, while those of nitrate, ammonium, and SV-OOA showed a narrower peak at ~08:00-13:00. The later morning and early afternoon peak in the diurnal profiles of secondary aerosol species was likely caused by mixing down of pollutants aloft, which were likely produced in the residual layer decoupled from the boundary layer during night time. The mass spectrum of SV-OOA also showed similarity with that of

  11. 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.

  12. How much information do extinction and backscattering measurements contain about the chemical composition of atmospheric aerosol?

    NASA Astrophysics Data System (ADS)

    Kahnert, Michael; Andersson, Emma

    2017-03-01

    We theoretically and numerically investigate the problem of assimilating multiwavelength lidar observations of extinction and backscattering coefficients of aerosols into a chemical transport model. More specifically, we consider the inverse problem of determining the chemical composition of aerosols from these observations. The main questions are how much information the observations contain to determine the particles' chemical composition, and how one can optimize a chemical data assimilation system to make maximum use of the available information. We first quantify the information content of the measurements by computing the singular values of the scaled observation operator. From the singular values we can compute the number of signal degrees of freedom, Ns, and the reduction in Shannon entropy, H. As expected, the information content as expressed by either Ns or H grows as one increases the number of observational parameters and/or wavelengths. However, the information content is strongly sensitive to the observation error. The larger the observation error variance, the lower the growth rate of Ns or H with increasing number of observations. The right singular vectors of the scaled observation operator can be employed to transform the model variables into a new basis in which the components of the state vector can be partitioned into signal-related and noise-related components. We incorporate these results in a chemical data assimilation algorithm by introducing weak constraints that restrict the assimilation algorithm to acting on the signal-related model variables only. This ensures that the information contained in the measurements is fully exploited, but not overused. Numerical tests show that the constrained data assimilation algorithm provides a solution to the inverse problem that is considerably less noisy than the corresponding unconstrained algorithm. This suggests that the restriction of the algorithm to the signal-related model variables suppresses

  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. Chemical compositions of past soluble aerosols reconstructed from NEEM (Greenland) and Dome C (Antarctica) ice cores

    NASA Astrophysics Data System (ADS)

    Oyabu, Ikumi; Iizuka, Yoshinori; Fukui, Manabu; Fischer, Hubertus; Schüpbach, Simon; Gfeller, Gideon; Mulvaney, Robert; Hansson, Margareta

    2015-04-01

    Polar ice core preserve past atmospheric aerosols, which is a useful proxy for understanding the interaction between climate changes and atmospheric aerosols. One useful technique for reconstructing past soluble aerosols from ice core is the determination of dissolved ion species. However, since salts and acids melt into ions, chemical compositions of soluble aerosols in the ice cores have not been cleared. To clarify the temporal variations in the chemical compositions of past soluble aerosols, this study investigated chemical compositions of soluble particles preserved in the NEEM (Greenland) and Dome C (Antarctica) ice cores using new method 'ice-sublimation method'. The ice-sublimation method can extract soluble salts particles as a solid state without melting. The ice core samples are selected from the sections from the last termination (the Last Glacial Maximum (LGM) to Holocene) of Dome C (inland Antarctica) and NEEM ice cores. Using ice-sublimation method, soluble salts particles were extracted. Chemical components of extracted particles were analysed by scanning electron microscope and energy dispersive spectroscopy, and micro-Raman spectroscopy. The major components of soluble salts particles in the Dome C ice core are CaSO4, Na2SO4 and NaCl. The CaSO4 and NaCl fractions were high in the first half of the last termination, whereas the Na2SO4 fraction is high in the latter half of the last termination. The major components of soluble salts particles in the NEEM ice core are CaCO3, CaSO4, NaCl and Na2SO4. The fractions of CaCO3, CaSO4 and NaCl were high in LGM, whereas those of NaCl and Na2SO4 were high in Holocene. The changes in the salts compositions in Dome C ice core are mainly controlled by concentration of terrestrial material (Ca2+). In the first half of the last termination, most of the terrestrial material (CaCO3) reacted with H2SO4 but some of sea-salt (NaCl) was not reacted with H2SO4 due to high Ca2+ concentration. As a result, the CaSO4 and Na

  15. 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

  16. Influence of Aerosol Chemical Composition on Heterogeneous Ice Formation under Mid-Upper Troposphere Conditions

    NASA Astrophysics Data System (ADS)

    Kanji, Z. A.; Niemand, M.; Saathoff, H.; Möhler, O.; Chou, C.; Abbatt, J.; Stetzer, O.

    2011-12-01

    Aerosols are involved in cooling/warming the atmosphere directly via interaction with incoming solar radiation (aerosol direct effect), or via their ability to act as cloud condensation or ice nuclei (IN) and thus play a role in cloud formation (indirect effect). In particular, the physical properties of aerosols such as size and solubility and chemical composition can influence their behavior and fate in the atmosphere. Ice nucleation taking place via IN is termed as heterogeneous ice nucleation and can take place with via deposition (ice forming on IN directly from the vapor phase), condensation/immersion (freezing via formation of the liquid phase on IN) or condensation (IN colliding with supercooled liquid drops). This presentation shows how the chemical composition and surface area of various tropospherically relevant aerosols influence conditions of temperature (T) and relative humidity (RH) required for heterogeneous ice formation conditions in the mid-upper troposphere regime (253 - 220K)? Motivation for this comes first from, the importance of being able to predict ice formation accurately so as to understand the hydrological cycle since the ice is the primary initiator of precipitation forming clouds. Second, the tropospheric budget of water vapour, an especially active greenhouse gas is strongly influenced by ice nucleation and growth. Third, ice surfaces in the atmosphere act as heterogeneous surfaces for chemical reactions of trace gases (e.g., SO2, O3, NOx and therefore being able to accurately estimate ice formation rates and quantify ice surface concentrations will allow a more accurate calculation of trace gas budgets in the troposphere. Ice nucleation measurements were conducted using a self-developed continuous flow diffusion chamber and static chamber. A number of tropospherically relevant particulates with naturally-varying and laboratory-modified surface chemistry/structure were investigated for their ice formation efficiency based on highest

  17. Laboratory analogues simulating Titan's atmospheric aerosols: Compared chemical compositions of grains and thin films

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

    Two sorts of solid organic samples can be produced in laboratory experiments simulating Titan's atmospheric reactivity: grains in the volume and thin films on the reactor walls. We expect that grains are more representative of Titan's atmospheric aerosols, but films are used to provide optical indices for radiative models of Titan's atmosphere. The aim of the present study is to address if these two sorts of analogues are chemically equivalent or not, when produced in the same N2-CH4 plasma discharge. The chemical compositions of both these materials are measured by using elemental analysis, XPS analysis and Secondary Ion Mass Spectrometry. The main parameter probed is the CH4/N2 ratio to explore various possible chemical regimes. We find that films are homogeneous but significantly less rich in nitrogen and hydrogen than grains produced in the same experimental conditions. This surprising difference in their chemical compositions could be explained by the efficient etching occurring on the films, which stay in the discharge during the whole plasma duration, whereas the grains are ejected after a few minutes. The higher nitrogen content in the grains possibly involves a higher optical absorption than the one measured on the films, with a possible impact on Titan's radiative models.

  18. 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.

  19. Chemical Properties of Combustion Aerosols: An Overview

    EPA Science Inventory

    A wide variety of pyrogenic and anthropogenic sources emit fine aerosols to the atmosphere. The physical and chemical properties of these aerosols are of interest due to their influence on climate, human health, and visibility. Aerosol chemical composition is remarkably complex. ...

  20. Evaluation of the performance of four chemical transport models in predicting the aerosol chemical composition in Europe in 2005

    NASA Astrophysics Data System (ADS)

    Prank, Marje; Sofiev, Mikhail; Tsyro, Svetlana; Hendriks, Carlijn; Semeena, Valiyaveetil; Vazhappilly Francis, Xavier; Butler, Tim; Denier van der Gon, Hugo; Friedrich, Rainer; Hendricks, Johannes; Kong, Xin; Lawrence, Mark; Righi, Mattia; Samaras, Zissis; Sausen, Robert; Kukkonen, Jaakko; Sokhi, Ranjeet

    2016-05-01

    Four regional chemistry transport models were applied to simulate the concentration and composition of particulate matter (PM) in Europe for 2005 with horizontal resolution ~ 20 km. The modelled concentrations were compared with the measurements of PM chemical composition by the European Monitoring and Evaluation Programme (EMEP) monitoring network. All models systematically underestimated PM10 and PM2.5 by 10-60 %, depending on the model and the season of the year, when the calculated dry PM mass was compared with the measurements. The average water content at laboratory conditions was estimated between 5 and 20 % for PM2.5 and between 10 and 25 % for PM10. For majority of the PM chemical components, the relative underestimation was smaller than it was for total PM, exceptions being the carbonaceous particles and mineral dust. Some species, such as sea salt and NO3-, were overpredicted by the models. There were notable differences between the models' predictions of the seasonal variations of PM, mainly attributable to different treatments or omission of some source categories and aerosol processes. Benzo(a)pyrene concentrations were overestimated by all the models over the whole year. The study stresses the importance of improving the models' skill in simulating mineral dust and carbonaceous compounds, necessity for high-quality emissions from wildland fires, as well as the need for an explicit consideration of aerosol water content in model-measurement comparison.

  1. 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

  2. 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

  3. 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.

  4. Wintertime aerosol chemical composition, volatility, and spatial variability in the greater London area

    NASA Astrophysics Data System (ADS)

    Xu, L.; Williams, L. R.; Young, D. E.; Allan, J. D.; Coe, H.; Massoli, P.; Fortner, E.; Chhabra, P.; Herndon, S.; Brooks, W. A.; Jayne, J. T.; Worsnop, D. R.; Aiken, A. C.; Liu, S.; Gorkowski, K.; Dubey, M. K.; Fleming, Z. L.; Visser, S.; Prevot, A. S. H.; Ng, N. L.

    2015-08-01

    The composition of PM1 (particulate matter with diameter less than 1 μm) in the greater London area was characterized during the Clean Air for London (ClearfLo) project in winter 2012. Two High-Resolution Time-of-Flight Aerosol Mass Spectrometers (HR-ToF-AMS) were deployed at a rural site (Detling, Kent) and an urban site (North Kensington, London). The simultaneous and high-temporal resolution measurements at the two sites provide a unique opportunity to investigate the spatial distribution of PM1. We find that the organic aerosol (OA) concentration is comparable between the rural and urban sites, but the sources of OA are distinctly different. The concentration of solid fuel OA at the urban site is about twice as high as at the rural site, due to elevated domestic heating in the urban area. While the concentrations of oxygenated OA (OOA) are well-correlated between the two sites, the OOA concentration at the rural site is almost twice that of the urban site. At the rural site, more than 70 % of the carbon in OOA is estimated to be non-fossil, which suggests that OOA is likely related to aged biomass burning considering the small amount of biogenic SOA in winter. Thus, it is possible that the biomass burning OA contributes a larger fraction of ambient OA in wintertime than what previous field studies have suggested. A suite of instruments was deployed downstream of a thermal denuder (TD) to investigate the volatility of PM1 species at the rural Detling site. After heating at 250 °C in the TD, 40 % of the residual mass is OA, indicating the presence of non-volatile organics in the aerosol. Although the OA associated with refractory black carbon (rBC, measured by a soot-particle aerosol mass spectrometer) only accounts for < 10 % of the total OA (measured by a HR-ToF-AMS) at 250 °C, the two measurements are well-correlated, suggesting that the non-volatile organics have similar sources or have undergone similar chemical processing as rBC in the atmosphere

  5. 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

  6. Pattern of aerosol mass loading and chemical composition over the atmospheric environment of an urban coastal station

    NASA Astrophysics Data System (ADS)

    Bindu, G.; Nair, Prabha R.; Aryasree, S.; Hegde, Prashant; Jacob, Salu

    2016-02-01

    Aerosol sampling was carried out at four locations in and around Cochin (9°58‧ N, 76°17‧ E), an urban area, located on the southwest coast of India. The gravimetric estimates of aerosol mass loading showed wide range from 78 μg m-3 to >450 μg m-3, occasionally reaching values >500 μg m-3, associated with regional source characteristics. Most of the values were above the air quality standard. Both boundary layer and synoptic scale airflow pattern play role in the temporal features in aerosol mass loading and chemical composition. Chemical analysis of the aerosol samples were done for anionic species viz; F-, Cl-, Br-, NO2-,   NO3-,   PO43-,   SO42- and metallic/cationic species viz; Na, Ca, K, Mg, NH4+, Fe, Al, Cu, Mg, Pb, etc using Ion Chromatography, Atomic Absorption Spectroscopy (AAS) and Inductively Coupled Plasma- Atomic Emission Spectroscopy (ICP-AES). At all the locations, extremely high mass concentration of SO42- was observed with the mean value of 13±6.4 μg m-3 indicating the strong anthropogenic influence. Statistical analysis of the chemical composition data was carried out and the principal factors presented. Seasonal variation of these chemical species along with their percentage contributions and regional variations were also examined. Increase in level of Na in aerosol samples indicated the influence of monsoonal activity. Most of the species showed mass concentrations well above those measured over another coastal site Thiruvananthapuram (8°29‧ N, 76°57‧ E) situated ~220 km south of Cochin revealing the highly localized aerosol features.

  7. Chemical composition and sources of organic aerosols over London from the ClearfLo 2012 campaigns

    NASA Astrophysics Data System (ADS)

    Finessi, Emanuela; Holmes, Rachel; Hopkins, James; Lee, James; Harrison, Roy; Hamilton, Jacqueline

    2014-05-01

    Air quality in urban areas represents a major public health issue with around one third of the European population concentrated in cities and numbers expected to increase at global scale, particularly in developing countries. Particulate matter (PM) represents a primary threat for human health as numerous studies have confirmed the association between increased levels of cardiovascular and respiratory diseases with the exposure to PM. Despite considerable efforts made in improving air quality and progressively stricter emissions regulations, the PM concentrations have not changed much over the past decades for reasons that remain unclear, and highlight that studies on PM source apportionment are required for the formulation of effective policy. We investigated the chemical composition of organic aerosol (OA) collected during two intensive field campaigns held in winter and summer 2012 in the frame of the project Clean air for London (http://www.clearflo.ac.uk/). PM samples were collected both at a city background site (North Kensington) and at a rural site 50 km southeast of London (Detling) with 8 to 24 hours sampling schedule and analysed using off-line methods. Thermal-optical analysis was used to quantify OC-EC components while a suite of soft ionization mass spectrometric techniques was deployed for detailed chemical characterization. Liquid chromatography mass Spectrometry (LC-MSn) was mostly used for the simultaneous detection and quantification of various tracers for both primary and secondary OA sources. Well-established markers for wood burning primary OA like levoglucosan and azelaic acid were quantified together with various classes of nitroaromatics including methyl-nitrocatechols that are potential tracers for wood burning secondary OA. In addition, oxidation products of biogenic VOCs such as isoprene and monoterpenes were also quantified for both seasons and sites. A non-negligible contribution from biogenic SOA to urban OA was found in summertime

  8. 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

  9. Physical and Chemical Properties of Anthropogenic Aerosols: An Overview

    EPA Science Inventory

    Aerosol chemical composition is complex. Combustion aerosols can comprise tens of thousands of organic compounds, refractory brown and black carbon, heavy metals, cations, anions, salts, and other inorganic phases. Aerosol organic matter normally contains semivolatile material th...

  10. 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

  11. Aerosols Collected at a Tropical Marine Environment: Size-Resolved Chemical Composition Using IC, TOC, and Thermal-Optical Analyses

    NASA Astrophysics Data System (ADS)

    Morales-García, F.; Mayol-Bracero, O. L.; Repollet-Pedrosa, M.; Kasper-Giebl, A.; Ramírez-Santa Cruz, C.; Puxbaum, H.

    2009-05-01

    Size-resolved chemical characterization was performed on aerosol samples collected at two different marine sites in the tropics: Dian Point (DP), Antigua and Cape San Juan (CSJ), Puerto Rico. A 13-stage Dekati low- pressure impactor (Dp 0.1 to 10 μm), a 10-stage micro-orifice uniform deposit impactor (Dp 0.054 to 18 μm), and stacked-filter units (Dp < 1.7 μm) were used to collect the samples. Na+, NH4+, K+, Mg2+, Ca2+, Cl-, NO2-, NO3-, SO42-, acetate, formate, malonate, and oxalate were determined using ion chromatography (IC). Thermal-optical analysis (TOA) was used to determine the concentrations of aerosol total carbon (TC), organic carbon (OC), and elemental carbon (EC). Five-day back trajectories calculated using NOAA's HYSPLIT (HYbrid Single-Particle Lagrangian Integrated Trajectory) model identified air masses coming from the North Atlantic (maritime air), Northwest Africa (desert dust), and North America (anthropogenic pollution). Size-resolved chemical characterization of aerosol samples using IC and TOA confirmed that aerosols become aged as they are transported to the Caribbean and their composition depends on the air mass origin. Gravimetric analyses showed that average fine mass concentrations for CSJ station were higher than for DP station (CSJ: 1.9 μg m-3; DP: 1.2 μg m-3). The aerosol chemical composition changed with air masses of different origin and with different pollution levels. In both locations the predominant water-soluble ions in the fine aerosol fraction were Cl-, Na+, and SO42-. Sulphate was observed in higher concentrations during the polluted case and particulate organic matter concentrations were higher for the maritime case. During desert dust events an increase in Ca2+ and Mg2+ of 4 and 2 times, respectively, was observed mainly in the coarse mode. Results for the size-resolved chemical composition and complete aerosol chemical apportionment including the residual mass will be presented.

  12. Wintertime aerosol chemical composition, volatility, and spatial variability in the greater London area

    DOE PAGES

    Xu, L.; Williams, L. R.; Young, D. E.; ...

    2016-02-02

    The composition of PM1 (particulate matter with diameter less than 1 µm) in the greater London area was characterized during the Clean Air for London (ClearfLo) project in winter 2012. Two high-resolution time-of-flight aerosol mass spectrometers (HR-ToF-AMS) were deployed at a rural site (Detling, Kent) and an urban site (North Kensington, London). The simultaneous and high-temporal resolution measurements at the two sites provide a unique opportunity to investigate the spatial distribution of PM1. We find that the organic aerosol (OA) concentration is comparable between the rural and urban sites, but the contribution from different sources is distinctly different between the two sites.more » The concentration of solid fuel OA at the urban site is about twice as high as at the rural site, due to elevated domestic heating in the urban area. While the concentrations of oxygenated OA (OOA) are well-correlated between the two sites, the OOA concentration at the rural site is almost twice that of the urban site. At the rural site, more than 70 % of the carbon in OOA is estimated to be non-fossil, which suggests that OOA is likely related to aged biomass burning considering the small amount of biogenic SOA in winter. Thus, it is possible that the biomass burning OA contributes a larger fraction of ambient OA in wintertime than what previous field studies have suggested. A suite of instruments was deployed downstream of a thermal denuder (TD) to investigate the volatility of PM1 species at the rural Detling site. After heating at 250 °C in the TD, 40 % of the residual mass is OA, indicating the presence of non-volatile organics in the aerosol. Although the OA associated with refractory black carbon (rBC; measured by a soot-particle aerosol mass spectrometer) only accounts for < 10 % of the total OA (measured by a HR-ToF-AMS) at 250 °C, the two measurements are well-correlated, suggesting that the non-volatile organics have similar sources or have

  13. Wintertime aerosol chemical composition, volatility, and spatial variability in the greater London area

    NASA Astrophysics Data System (ADS)

    Xu, L.; Williams, L. R.; Young, D. E.; Allan, J. D.; Coe, H.; Massoli, P.; Fortner, E.; Chhabra, P.; Herndon, S.; Brooks, W. A.; Jayne, J. T.; Worsnop, D. R.; Aiken, A. C.; Liu, S.; Gorkowski, K.; Dubey, M. K.; Fleming, Z. L.; Visser, S.; Prévôt, A. S. H.; Ng, N. L.

    2016-02-01

    The composition of PM1 (particulate matter with diameter less than 1 µm) in the greater London area was characterized during the Clean Air for London (ClearfLo) project in winter 2012. Two high-resolution time-of-flight aerosol mass spectrometers (HR-ToF-AMS) were deployed at a rural site (Detling, Kent) and an urban site (North Kensington, London). The simultaneous and high-temporal resolution measurements at the two sites provide a unique opportunity to investigate the spatial distribution of PM1. We find that the organic aerosol (OA) concentration is comparable between the rural and urban sites, but the contribution from different sources is distinctly different between the two sites. The concentration of solid fuel OA at the urban site is about twice as high as at the rural site, due to elevated domestic heating in the urban area. While the concentrations of oxygenated OA (OOA) are well-correlated between the two sites, the OOA concentration at the rural site is almost twice that of the urban site. At the rural site, more than 70 % of the carbon in OOA is estimated to be non-fossil, which suggests that OOA is likely related to aged biomass burning considering the small amount of biogenic SOA in winter. Thus, it is possible that the biomass burning OA contributes a larger fraction of ambient OA in wintertime than what previous field studies have suggested. A suite of instruments was deployed downstream of a thermal denuder (TD) to investigate the volatility of PM1 species at the rural Detling site. After heating at 250 °C in the TD, 40 % of the residual mass is OA, indicating the presence of non-volatile organics in the aerosol. Although the OA associated with refractory black carbon (rBC; measured by a soot-particle aerosol mass spectrometer) only accounts for < 10 % of the total OA (measured by a HR-ToF-AMS) at 250 °C, the two measurements are well-correlated, suggesting that the non-volatile organics have similar sources or have undergone similar chemical

  14. Characteristics of aerosol size distributions and chemical compositions during wintertime pollution episodes in Beijing

    NASA Astrophysics Data System (ADS)

    Liu, Zirui; Hu, Bo; Zhang, Junke; Yu, Yangchun; Wang, Yuesi

    2016-02-01

    To characterize the features of particle pollution, continuous measurements of particle number size distributions and chemical compositions were performed at an urban site in Beijing in January 2013. The particle number and volume concentration from 14 nm to 1000 nm were (37.4 ± 15.3) × 103 cm- 3 and (85.2 ± 65.6) μm3 cm- 3, respectively. N-Ait (Aitken mode) particles dominated the number concentration, whereas N-Acc (accumulation mode) particles dominated the volume concentration. Submicron particles were generally characterized by a high content of organics and SO42 -, and a low level of NO3- and Cl-. Two types of pollution episodes were observed, characterized by the "explosive growth" (EXP) and "sustained growth" (SUS) of PM2.5. Fine particles greater than 100 nm dominated the volume concentration during the ends of these pollution episodes, shifting the maximum of the number size distribution from 60 nm to greater than 100 nm in a few hours (EXP) or a few days (SUS). Secondary transformation is the main reason for the pollution episodes; SO42 -, NO3- and NH4+ (SNA) accounted for approximately 42% (EXP) and greater than 60% (SUS) of the N-Acc particle mass increase. The size distributions of particulate organics and SNA varied on timescales of hours to days, the characteristics of which changed from bimodal to unimodal during the evolution of haze episodes. The accumulation mode (peaking at approximately 500-700 nm) was dominated by organics that appeared to be internally mixed with nitrate or sulfate. The sulfate was most likely formed via heterogeneous reactions, because the SOR was constant under dry conditions (RH < 50%) and began to increase when RH > 50%, suggesting an important contribution from heterogeneous reactions with abundant aerosol water under wet conditions. Finally, the correlations between [NO3-]/[SO42 -] and [NH4+]/[SO42 -] suggest that the homogenous reaction between HNO3 and NH3 dominated the formation of nitrate under conditions of

  15. Evolution of biomass burning aerosol over the Amazon: airborne measurements of aerosol chemical composition, microphysical properties, mixing state and optical properties during SAMBBA

    NASA Astrophysics Data System (ADS)

    Morgan, W.; Allan, J. D.; Flynn, M.; Darbyshire, E.; Hodgson, A.; Liu, D.; O'Shea, S.; Bauguitte, S.; Szpek, K.; Johnson, B.; Haywood, J.; Longo, K.; Artaxo, P.; Coe, H.

    2013-12-01

    Biomass burning represents one of the largest sources of particulate matter to the atmosphere, resulting in a significant perturbation to the Earth's radiative balance coupled with serious impacts on public health. On regional scales, the impacts are substantial, particularly in areas such as the Amazon Basin where large, intense and frequent burning occurs on an annual basis for several months. Absorption by atmospheric aerosols is underestimated by models over South America, which points to significant uncertainties relating to Black Carbon (BC) aerosol properties. Initial results from the South American Biomass Burning Analysis (SAMBBA) field experiment, which took place during September and October 2012 over Brazil on-board the UK Facility for Airborne Atmospheric Measurement (FAAM) BAe-146 research aircraft, are presented here. Aerosol chemical composition was measured by an Aerodyne Aerosol Mass Spectrometer (AMS) and a DMT Single Particle Soot Photometer (SP2). The physical, chemical and optical properties of the aerosols across the region will be characterized in order to establish the impact of biomass burning on regional air quality, weather and climate. The aircraft sampled a range of conditions including sampling of pristine Rainforest, fresh biomass burning plumes, regional haze and elevated biomass burning layers within the free troposphere. The aircraft sampled biomass burning aerosol across the southern Amazon in the states of Rondonia and Mato Grosso, as well as in a Cerrado (Savannah-like) region in Tocantins state. This presented a range of fire conditions, in terms of their number, intensity, vegetation-type and their combustion efficiencies. Near-source sampling of fires in Rainforest environments suggested that smouldering combustion dominated, while flaming combustion dominated in the Cerrado. This led to significant differences in aerosol chemical composition, particularly in terms of the BC content, with BC being enhanced in the Cerrado

  16. Chemical aerosol Raman detector

    NASA Astrophysics Data System (ADS)

    Aggarwal, R. L.; Farrar, L. W.; Di Cecca, S.; Amin, M.; Perkins, B. G.; Clark, M. L.; Jeys, T. H.; Sickenberger, D. W.; D'Amico, F. M.; Emmons, E. D.; Christesen, S. D.; Kreis, R. J.; Kilper, G. K.

    2017-03-01

    A sensitive chemical aerosol Raman detector (CARD) has been developed for the trace detection and identification of chemical particles in the ambient atmosphere. CARD includes an improved aerosol concentrator with a concentration factor of about 40 and a CCD camera for improved detection sensitivity. Aerosolized isovanillin, which is relatively safe, has been used to characterize the performance of the CARD. The limit of detection (SNR = 10) for isovanillin in 15 s has been determined to be 1.6 pg/cm3, which corresponds to 6.3 × 109 molecules/cm3 or 0.26 ppb. While less sensitive, CARD can also detect gases. This paper provides a more detailed description of the CARD hardware and detection algorithm than has previously been published.

  17. Seasonality of the mass concentration and chemical composition of aerosols around an urbanized basin in East Asia

    NASA Astrophysics Data System (ADS)

    Chou, C. C.-K.; Hsu, W.-C.; Chang, S.-Y.; Chen, W.-N.; Chen, M.-J.; Huang, W.-R.; Huang, S.-H.; Tsai, C.-Y.; Chang, S.-C.; Lee, C.-T.; Liu, S.-C.

    2017-02-01

    This study investigated seasonal variations in the mass concentration and chemical composition of ambient aerosols observed at three stations (coastal, mountainous, and downtown sites) in northern Taiwan from March 2009 to February 2012. The results show that the major aerosol components include ammonium, sulfate, nitrate, sea salt, dust, organic carbon, and elemental carbon, whereas the mass fraction of each species depends on the sampling location and season. A significant correlation (r = 0.7-0.8) was observed in aerosol concentrations measured at the respective stations, indicating that aerosol concentrations were dominated by regional-scale factors. Ammonium, sulfate, and nitrate consistently reached respective peak values in the spring in conjunction with dust particle levels. This shows that the transport of dust and particulate air pollutants from the Asian continent has affected the atmospheric environment in this area. Distinct seasonality was observed for sea salt and secondary organic carbon (SOC): sea salt levels peaked in the autumn, whereas SOC levels peaked in the summer, implying that their sources were regulated by independent seasonal factors. Correlation between sea salt concentration and surface wind speed was derived from coastal measurements and showed a high value for the wind speed sensitivity parameter of around 0.37 for our location. In addition, it was revealed that the SOC concentration in aerosols was positively correlated with oxidant photolysis index (Ox × UVB), suggesting that the SOC seasonality was dominated by hydroxyl radical production.

  18. Chemical Composition, Seasonal Variation and Size distribution of Atmospheric Aerosols at an Alpine Site in Guanzhong Plain, China

    NASA Astrophysics Data System (ADS)

    Li, J.

    2015-12-01

    PM10 and size-segregated aerosol samples were collected at Mt. Hua (2065 a.s.m) in central China, and determined for carbonaceous fraction, ions and organic composition. The concentration of most chemical compositions in summer are lower than those in winter, due to decreased emissions of biomass and coal burning for house heating. High temperature and relative humidity (RH) conditions are favorable for secondary aerosol formation, resulting in higher concentrations of SO42- and NH4+ in summer. Non-dehydrated sugars are increased in summer because of the enhanced metabolism. Carbon preference index results indicate that n-alkanes at Mt. Hua are derived mostly by plant wax. Low Benzo(a)pyrene/Benzo(a)pyrene ratios indicate that mountain aerosols are more aged. Concentrations of biogenic (BSOA, the isoprene/pinene/caryophyllene oxidation products) and anthropogenic (ASOA, mainly aromatic acids) SOA positively correlated with temperature . However, a decreasing trend of BSOA concentration with an increase in RH was observed during the sampling period, although a clear trend between ASOA and RH was not found. Based on the AIM Model calculation, we found that during the sampling period an increase in RH resulted in a decrease in the aerosol acidity and thus reduced the effect of acid-catalysis on BSOA formation. Size distributions of K+ and NH4+ present as an accumulation mode, in contrast to Ca2+ and Mg2+, which are mainly existed in coarse particles. SO42- and NO3- show a bimodal pattern. Dehydrated sugars, fossil fuel derived n-alkanes and PAHs presented unimode size distribution, whereas non-dehydrated sugars and plant wax derived n-alkanes showed bimodal pattern. Most of the determined BSOA are formed in the aerosol phase and enriched in the fine mode except for cis-pinonic acid, which is formed in the gas phase and subsequently partitioned into aerosol phase and thus presents a bimodal pattern with a major peak in the coarse mode.

  19. Long-term measurement of aerosol chemical composition in Athens, Greece.

    NASA Astrophysics Data System (ADS)

    Paraskevopoulou, Despina; Liakakou, Eleni; Theodosi, Christina; Gerasopoulos, Evangelos; Mihalopoulos, Nikolaos

    2014-05-01

    The collection of our samples was conducted for a period of five years (2008 - 2013) in Athens, Greece. The site is situated at the premises of the National Observatory of Athens on Penteli Hill, northeast Athens suburbs, and is considered an urban background station. The aim of our study was a first long-term estimation of the chemical mass closure of aerosol. For the purposes of the study, we applied three filter samplers during the sampling period: two Partisol FRM Model 2000 air samplers (one of them collecting PM10 and the other PM2.5 fractions of aerosol) and one Dichotomous Partisol auto-sampler (with PM2.5 and PM2.5-10 inlet). Aerosols were collected on Whatman QM-A quartz fiber filters and the mass of the collected samples was estimated by weighing the pre-combusted filters before and after sampling, under controlled conditions, using a microbalance. All quartz filters were analysed for organic (OC) and elemental carbon (EC) by a thermal - optical transmission technique. The concentration of water soluble organic carbon (WSOC) was defined for each filter using a total organic carbon analyzer, while the content in main water soluble ions (Cl-, Br-, NO-3, SO4-2, PO4-3, C2O4-2, NH4+, K+, Na+, Mg+2, Ca+2) was determined by ion chromatography. Additionally the filters were analyzed for trace metals by inductively coupled plasma optical emission spectrometry (ICP-OES). Aerosol chemical mass closure calculations were conducted for the PM2.5 fraction. The area of Athens is characterized by aged aerosol that can originate from the marine boundary layer, the European mainland and occasionally from North African desert areas. The contribution of dust and particulate organic matter on PM levels was estimated taking into consideration the location of the sampling site, while identification and evaluation of sources was performed. Additionally, non-sea salt concentrations of the main ions were estimated to complete the chemical closure in the extended area. According to

  20. 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.

  1. Analysis of the Effects of Chemical Composition and Humidity on Visibility using Highly Time Resolved Aerosol Data

    NASA Astrophysics Data System (ADS)

    Lunden, M. M.; Brown, N. J.; Liu, D.; Tonse, S.

    2005-12-01

    Transported aerosols from populated and industrial areas result in regional haze that causes visibility degradation in areas valued for their scenic beauty, such as the National Parks. These areas are designated as Class I Areas in the United States, and there are specific visibility goals put forth to ultimately return these areas to natural conditions. To both understand current conditions and chart progress towards meeting these goals requires measurement of important aerosol species and an understanding of how these different aerosol species affect light attenuation to allow for predictive modeling capabilities. The current investigation seeks to understand if more highly time resolved measurements of chemically speciated particle mass, relative humidity, scattering, and absorption would enable a better estimation of extinction as the relationship between these variables is non-linear. Our particular objective is to explore the contributions of the aerosol species mentioned above to visibility degradation, and the role played by relative humidity. We performed analyses on a data set collected in Central California from the intensive ambient aerosol sampling campaign conducted from 2000 summer-2001 winter1. The data include PM-2.5 mass concentrations of nitrate, sulfate, organic carbon and black carbon aerosol, as well as simultaneous measurements on light scattering, ambient temperature and relative humidity. The dataset is highly time-resolved, allowing the affect of temporal variations of particle chemical composition and meteorological features to be considered. The final results provide response curves that allow calculation of light scattering given aerosol concentrations and relative humidity. Our results are compared with those obtained using formulae suggested for analysis of IMPROVE (a regional haze monitoring network2) data collected under lower temporal resolution to understand the effects of temporal resolution on the characteristics of the

  2. Physical and Chemical Properties of Anthropogenic Aerosols: An overview

    EPA Science Inventory

    A wide variety of anthropogenic sources emit fine aerosols to the atmosphere. The physical and chemical properties of these aerosols are of interest due to their influence on climate, human health, and visibility. Aerosol chemical composition is complex. Combustion aerosols can c...

  3. Aerosol Types using Passive Remote Sensing: Global Distribution, Consistency Check, Total-Column Investigation and Translation into Composition Derived from Climate and Chemical Transport Model

    NASA Astrophysics Data System (ADS)

    Kacenelenbogen, M. S.; Dawson, K. W.; Johnson, M. S.; Burton, S. P.; Redemann, J.; Hasekamp, O. P.; Hair, J. W.; Ferrare, R. A.; Butler, C. F.; Holben, B. N.; Beyersdorf, A. J.; Ziemba, L. D.; Froyd, K. D.; Dibb, J. E.; Shingler, T.; Sorooshian, A.; Jimenez, J. L.; Campuzano Jost, P.; Jacob, D. J.

    2015-12-01

    To improve the predictions of aerosol composition in chemical transport models (CTMs) and global climate models (GCMs), we have developed an aerosol classification algorithm (called Specified Clustering and Mahalanobis Classification, SCMC) that assigns an aerosol type to multi-parameter retrievals by spaceborne, airborne or ground based passive remote sensing instruments [Russell et al., 2014]. The aerosol types identified by our scheme are pure dust, polluted dust, urban-industrial/developed economy, urban-industrial/developing economy, dark biomass smoke, light biomass smoke and pure marine. We apply the SCMC method to two different total-column datasets of aerosol optical properties: inversions from the ground-based AErosol RObotic NETwork (AERONET) and retrievals from the space-borne POLDER (Polarization and Directionality of Earth's Reflectances) instrument. The POLDER retrievals that we use differ from the standard POLDER retrievals [Deuzé et al., 2001] as they make full use of multi-angle, multispectral polarimetric data [Hasekamp et al., 2011]. We analyze agreement in the aerosol types inferred from both AERONET and POLDER globally. Then, we investigate how our total-column "effective" SCMC aerosol types relate to different aerosol types within the column (i.e. either a mixture of different types within one layer in the vertical or the stacking of different aerosol types within the vertical column). For that, we compare AERONET-SCMC aerosol types to collocated NASA LaRC HSRL vertically resolved aerosol types [Burton et al., 2012] during the SEAC4RS and DISCOVER-AQ airborne field experiments, mostly over Texas in Aug-Sept 2013. Finally, in order to evaluate the GEOS-Chem CTM aerosol types, we translate each of our SCMC aerosol type into a unique distribution of GEOS-Chem aerosol composition (e.g. biomass burning, dust, sulfate, sea salt). We bridge the gap between remote sensing and model-inferred aerosol types by using multiple years of collocated AERONET

  4. Global and Regional Impacts of HONO on the Chemical Composition of Clouds and Aerosols

    NASA Technical Reports Server (NTRS)

    Elshorbany, Y. F.; Crutzen, P. J.; Steil, B.; Pozzer, A.; Tost, H.; Lelieveld, J.

    2014-01-01

    Recently, realistic simulation of nitrous acid (HONO) based on the HONO / NOx ratio of 0.02 was found to have a significant impact on the global budgets of HOx (OH + HO2) and gas phase oxidation products in polluted regions, especially in winter when other photolytic sources are of minor importance. It has been reported that chemistry-transport models underestimate sulphate concentrations, mostly during winter. Here we show that simulating realistic HONO levels can significantly enhance aerosol sulphate (S(VI)) due to the increased formation of H2SO4. Even though in-cloud aqueous phase oxidation of dissolved SO2 (S(IV)) is the main source of S(VI), it appears that HONO related enhancement of H2O2 does not significantly affect sulphate because of the predominantly S(IV) limited conditions, except over eastern Asia. Nitrate is also increased via enhanced gaseous HNO3 formation and N2O5 hydrolysis on aerosol particles. Ammonium nitrate is enhanced in ammonia-rich regions but not under ammonia-limited conditions. Furthermore, particle number concentrations are also higher, accompanied by the transfer from hydrophobic to hydrophilic aerosol modes. This implies a significant impact on the particle lifetime and cloud nucleating properties. The HONO induced enhancements of all species studied are relatively strong in winter though negligible in summer. Simulating realistic HONO levels is found to improve the model measurement agreement of sulphate aerosols, most apparent over the US. Our results underscore the importance of HONO for the atmospheric oxidizing capacity and corroborate the central role of cloud chemical processing in S(IV) formation

  5. Global and Regional Impacts of HONO on the Chemical Composition of Clouds and Aerosols

    NASA Technical Reports Server (NTRS)

    Elshorbany, Y. F.; Crutzen, P. J.; Steil, B.; Pozzer, A.; Tost, H.; Lelieveld, J.

    2014-01-01

    Recently, realistic simulation of nitrous acid (HONO) based on the HONO/NO(sub x) ratio of 0.02 was found to have a significant impact on the global budgets of HO(sub x) (OH + HO2) and gas phase oxidation products in polluted regions, especially in winter when other photolytic sources are of minor importance. It has been reported that chemistry-transport models underestimate sulphate concentrations, mostly during winter. Here we show that simulating realistic HONO levels can significantly enhance aerosol sulphate (S(VI)) due to the increased formation of H2SO4. Even though in-cloud aqueous phase oxidation of dissolved SO2 (S(IV)) is the main source of S(VI), it appears that HONO related enhancement of H2O2 does not significantly affect sulphate because of the predominantly S(IV) limited conditions, except over eastern Asia. Nitrate is also increased via enhanced gaseous HNO3 formation and N2O5 hydrolysis on aerosol particles. Ammonium nitrate is enhanced in ammonia-rich regions but not under ammonia-limited conditions. Furthermore, particle number concentrations are also higher, accompanied by the transfer from hydrophobic to hydrophilic aerosol modes. This implies a significant impact on the particle lifetime and cloud nucleating properties. The HONO induced enhancements of all species studied are relatively strong in winter though negligible in summer. Simulating realistic HONO levels is found to improve the model measurement agreement of sulphate aerosols, most apparent over the US. Our results underscore the importance of HONO for the atmospheric oxidizing capacity and corroborate the central role of cloud chemical processing in S(IV) formation.

  6. Chemical composition of Titan's aerosols analogues characterized with a systematic pyrolysis-gas chromatography-mass spectrometry characterization

    NASA Astrophysics Data System (ADS)

    Szopa, Cyril; Raulin, Francois; Coll, Patrice; Cabane, Michel; GCMS Team

    2014-05-01

    The in situ chemical characterization of Titan's atmosphere was achieved in 2005 with two instruments present onboard the Huygens atmospheric probe : the Aerosol Collector and Pyrolyzer (ACP) devoted to collect and pyrolyse Titan's aerosols ; the Gas Chromatograph-Mass Spectrometer (GCMS) experiment devoted to analyze gases collected in the atmosphere or coming from the aerosols pyrolysis. The GCMS was developed by Hasso Niemann in the filiation of the quadrupole mass spectrometers he built for several former space missions. The main objectives were to : determine the concentration profile of the most abundant chemical species; seek for minor atmospheric organic species not detected with remote observations ; give a first view of the organic aerosols structure; characterize the condensed volatiles present at the surface (e.g. lakes) in case of survival of the probe to the landing impact. Taking into account for the potential complexity of the gaseous samples to be analyzed, it was decided to couple to the MS analyzer a gas chromatograph capable to separate volatile species from light inorganic molecules and noble gases, to organic compounds including aromatics. This was the first GCMS analyzer that worked in an extraterrestrial environment since the Viking missions on Mars. Even if the GCMS coupling mode did not provide any result of interest, it has been demonstrated to be functional during the Huygens descent. But, the direct MS analysis of the atmosphere, and the pyrolysis-MS analysis of aerosols allowed to make great discoveries which are still of primary importance to describe the Titan's lower atmosphere composition. This contribution aims at presenting this instrument that worked in the Titan's atmosphere, and summarizing the most important discoveries it allowed.

  7. 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.

  8. 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.

  9. Simulation of size-segregated aerosol chemical composition over northern Italy in clear sky and wind calm conditions

    NASA Astrophysics Data System (ADS)

    Landi, T. C.; Curci, G.; Carbone, C.; Menut, L.; Bessagnet, B.; Giulianelli, L.; Paglione, M.; Facchini, M. C.

    2013-05-01

    The present article compares the outputs of the 3-D regional chemistry-transport model (CTM) CHIMERE against observations of the size-resolved aerosol chemical composition over northern Italy in clear sky and wind calm conditions. Two 4-day intensive field campaigns were carried out in July 2007 and February 2008 at three sites (urban, rural and mountain backgrounds) in the framework of the AEROCLOUDS project. Predicted levels are in reasonable agreement with observations for the urban and rural sites. Bias ranges from - 30%, for the rural site in winter, to + 38%, for the urban site during summer. In addition, the model is able to capture both the daily evolution of the bulk aerosol mass as well as its spatial gradients. Aerosol size distribution and chemical composition remain difficult to predict. The largest discrepancies were found for secondary organic aerosol (SOA) during summer and nitrates during the cold season. Compared with observations, modelled size distribution is shifted towards fine mode in winter, and towards coarse mode in summer. More accurate predictions can be achieved for both seasons by tuning the gas to particle absorption process. By reducing the SOA absorption rate by 25% at the urban sampling site in summer, the correlation between observed and simulated SOA size distributions increases from - 0.30 to + 0.70, and the bias is reduced from 200% to 0%. In winter, increasing the intra-sectional flux of particles from smaller to larger ones by a factor of 5, the Pearson correlation coefficient calculated over the nitrate size distribution goes up to + 0.85, compared to + 0.50 from CTRL, also resulting in a better agreement with the size distribution of PM10. As expected, the nitrate bulk mass concentration does not vary with respect to the base-case, and therefore nitrate overestimation remains present in the model.

  10. 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.

  11. Wintertime aerosol chemical composition, volatility, and spatial variability in the greater London area

    NASA Astrophysics Data System (ADS)

    Xu, L.; Ng, N. L.; Williams, L. R.; Young, D. E.; Allan, J. D.; Coe, H.; Massoli, P.; Fortner, E.; Chhabra, P. S.; Herndon, S. C.; Brooks, B.; Jayne, J. T.; Worsnop, D. R.; Aiken, A. C.; Liu, S.; Gorkowski, K.; Dubey, M. K.; Fleming, Z.; Visser, S.; Prevot, A. S.

    2015-12-01

    In this study, we investigate the spatial distribution of PM1 in the greater London area during the Clean Air for London (ClearfLo) project in winter 2012 by applying two High-Resolution Time-of-Flight Aerosol Mass Spectrometers (HR-ToF-AMS) at a rural site (Detling, Kent) and an urban site (North Kensington, London). While the concentration of organic aerosol (OA) is comparable between the rural and urban sites, the OA sources are distinctly different. Due to elevated domestic heating in the urban area, the concentration of solid fuel OA at the urban site is about twice as high as at the rural site. In contrast, the OOA concentration at the rural site is almost twice that of the urban site. This is likely caused by a steep concentration gradient of OOA when air masses are advected from polluted mainland Europe. Taking advantage of low biogenic emissions in winter, the sources of OOA, which are highly uncertain, are investigated. Combing Positive Matrix Factorization (PMF) analysis and radiocarbon analysis, the majority of OOA is estimated to arise from aged biomass burning. We deploy a suite of instruments to investigate the organic volatility at the rural Detling site. After heating at 250°C in a thermal-denuder (TD), the mass fraction remaining of organics is 16%, which indicates the presence of non-volatile organics. By comparing the OA associated with refractory black carbon (measured by a soot-particle aerosol mass spectrometer) and total OA (measured by a HR-ToF-AMS), we proposed that the non-volatile organics have similar sources or have undergone similar chemical processing as refractory black carbon in the atmosphere. Finally, we will discuss the relationship between the volatility and the degree of oxidation of organics.

  12. Chemical composition of emissions from urban sources of fine organic aerosol

    SciTech Connect

    Hildemann, L.M.; Markowski, G.R.; Cass, G.R. )

    1991-04-01

    A dilution source sampling system was used to collect primary fine aerosol emissions from important sources of urban organic aerosol, including a boiler burning No. 2 fuel oil, a home fireplace, a fleet of catalyst-equipped and noncatalyst automobiles, heavy-duty diesel trucks, natural gas home appliances, and meat cooking operations. Alternative dilution sampling techniques were used to collect emissions from cigarette smoking and a roofing tar pot, and grab sample techniques were employed to characterize paved road dust, brake lining wear, and vegetative detritus. Organic aerosol constituted the majority of the fine aerosol mass emitted from many of the sources tested. Fine primary organic aerosol emissions within the heavily urbanized western portion of the Los Angeles Basin were determined to total 29.8 metric ton/day. Over 40% of these organic aerosol emissions are from anthropogenic pollution sources that are expected to emit contemporary (nonfossil) aerosol carbon, in good agreement with the available ambient monitoring data.

  13. Surface Chemical Composition of Size-fractionated Urban Walkway Aerosols Determined by XPS and ToF-SIMS

    NASA Astrophysics Data System (ADS)

    Wenjuan, Cheng; Lu-Tao, Weng; Yongjie, Li; Arthur, Lau; Chak, Chan; Chi-Ming, Chan

    2013-04-01

    In this study, aerosol particles with sizes ranging from 0.056 to 10 ?m were collected using a ten-stage impactor sampler (MOUDI) from a busy walkway of Hong Kong. The aerosol samples of each stage were examined with X-ray photoelectron spectroscopy (XPS). Size dependent distributions of the detected six key elements (N, S, Ca, Si, O, and C) were revealed together with the chemical states of N, S and C. The results indicated that aliphatic hydrocarbons were the dominant species on the surface of all particles while a small portion of graphitic carbon (due to elemental and aromatic hydrocarbons) was also detected on the surface of the particles with sizes ranging from 0.056 to 0.32 ?m. Organic oxygen- and nitrogen-containing surface groups as well as sulfates were more abundant on the surface of the particles with sizes ranging from 0.32 to 1 μm. Organic oxygen- and nitrogen-containing surface groups as well as sulfates were more abundant on the surface of the particles with sizes ranging from 0.32 to 1 μm. Inorganic salts and nitrates were found in coarse-mode particles. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used for detailed surface and near surface composition analysis. Principal component analysis (PCA) of the ToF-SIMS spectra confirmed the XPS results that aromatic hydrocarbons were associated with the nucleation-mode particles. Aliphatic hydrocarbons with O- and N-containing functional groups were associated with accumulation-mode particles and inorganic salts were related to the coarse-mode particles. Depth-profiling experiments were performed on three specific sets of samples (nucleation-, accumulation- and coarse-mode particles) to study their near-surface structures. It showed that organic compounds were concentrated on the very top surface of the coarse-mode particles with inorganics in the core. The accumulation-mode particles had thick coatings of diverse organic compositions. The nucleation-mode particles, which contained

  14. Chemical composition of size-segregated aerosols in Lhasa city, Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Wan, Xin; Kang, Shichang; Xin, Jinyuan; Liu, Bin; Wen, Tianxue; Wang, Pengling; Wang, Yuesi; Cong, Zhiyuan

    2016-06-01

    To reveal the chemical characteristics of size-segregated aerosols in the high-altitude city of Tibetan Plateau, eight-size aerosol samples were collected in Lhasa from March 2013 to February 2014. The annual mean of online PM2.5 was 25.0 ± 16.0 μg m- 3, which was much lower than Asian cities but similar with some European cities. The annual mean concentrations of organic carbon (OC, 7.92 μg m- 3 in PM2.1 and 12.66 μg m- 3 in PM9.0) and elemental carbon (EC, 1.00 μg m- 3 in PM2.1 and 1.21 μg m- 3 in PM9.0) in Lhasa aerosols were considerably lower than those heavily polluted cities such as Beijing and Xi'an, China and Kathmandu, Nepal. Sulfate, NO3-, NH4+ and Ca2 + were 0.75 ± 0.31, 0.82 ± 0.35, 0.38 ± 0.34 and 0.57 ± 0.29 μg m- 3 in fine particles while in coarse particles they were 0.57 ± 0.37, 0.73 ± 0.23, 0.07 ± 0.03 and 2.52 ± 1.37 μg m- 3, respectively. Secondary water-soluble ions composed 35.8% of the total ionic components in fine particles according to the established electroneutrality, while in coarse particles they took up only 9.3%. Ca2 + (40.6%) was the major component of the coarse particles. For seasonality, the concentrations of OC, EC, SO42 -, NH4+, K+, Ca2 +, Mg2 +, Cl- and Na+ presented higher values during late autumn and winter but were relatively lower in spring and summer. Nevertheless, NO3- was considerably higher in summer and autumn, presumably due to increased tourist-vehicle emissions. During winter and spring, [Ca2 +]/[NO3-+ SO42 -] ratios in coarse particles showed higher values of 7.31 and 6.17, respectively, emphasizing the dust influence. [NO3-]/[SO42 -] ratios in fine particles during spring, summer and autumn exceeding 1 indicated that the currently predominant vehicle exhaust makes a greater contribution to the aerosols. While more stationary sources such as coal and biomass burning existed in winter since the [NO3-]/[SO42 -] ratio was less than 1. Different sources and formation processes lead to a bimodal size

  15. Chemical composition, sources, and processes of urban aerosols during summertime in northwest China: insights from high-resolution aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    Xu, J.; Zhang, Q.; Chen, M.; Ge, X.; Ren, J.; Qin, D.

    2014-12-01

    An Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) was deployed along with a scanning mobility particle sizer (SMPS) and a multi-angle absorption photometer (MAAP) to measure the temporal variations of the mass loading, chemical composition, and size distribution of submicron particulate matter (PM1) in Lanzhou, northwest China, during 11 July-7 August 2012. The average (PM1 mass concentration including non-refractory (PM1 (NR-(PM1) measured by HR-ToF-AMS and black carbon (BC) measured by MAAP during this study was 24.5 μg m-3 (ranging from 0.86 to 105 μg m-3), with a mean composition consisting of 47% organics, 16% sulfate, 12% BC, 11% ammonium, 10% nitrate, and 4% chloride. Organic aerosol (OA) on average consisted of 70% carbon, 21% oxygen, 8% hydrogen, and 1% nitrogen, with the average oxygen-to-carbon ratio (O / C) of 0.33 and organic mass-to-carbon ratio (OM / OC) of 1.58. Positive matrix factorization (PMF) of the high-resolution organic mass spectra identified four distinct factors which represent, respectively, two primary OA (POA) emission sources (traffic and food cooking) and two secondary OA (SOA) types - a fresher, semi-volatile oxygenated OA (SV-OOA) and a more aged, low-volatility oxygenated OA (LV-OOA). Traffic-related hydrocarbon-like OA (HOA) and BC displayed distinct diurnal patterns, both with peak at ~ 07:00-11:00 (BJT: UTC +8), corresponding to the morning rush hours, while cooking-emission related OA (COA) peaked during three meal periods. The diurnal profiles of sulfate and LV-OOA displayed a broad peak between ~ 07:00 and 15:00, while those of nitrate, ammonium, and SV-OOA showed a narrower peak between ~ 08:00-13:00. The later morning and early afternoon maximum in the diurnal profiles of secondary aerosol species was likely caused by downward mixing of pollutants aloft, which were likely produced in the residual layer decoupled from the boundary layer during nighttime. The mass spectrum of SV-OOA was

  16. 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

  17. Measured and modelled cloud condensation nuclei (CCN) concentration in São Paulo, Brazil: the importance of aerosol size-resolved chemical composition on CCNhack concentration prediction

    NASA Astrophysics Data System (ADS)

    Almeida, G. P.; Brito, J.; Morales, C. A.; Andrade, M. F.; Artaxo, P.

    2014-07-01

    Measurements of cloud condensation nuclei (CCN), aerosol size distribution and non-refractory chemical composition were performed from 16 to 31 October 2012 in the São Paulo Metropolitan Area (SPMA), Brazil. CCN measurements were performed at 0.23, 0.45, 0.68, 0.90 and 1.13% water supersaturation and were subsequently compared with the Köhler theory, considering the chemical composition. Real-time chemical composition has been obtained by deploying, for the first time in the SPMA, an aerosol chemical ionization monitor (ACSM). CCN closure analyses were performed considering internal mixtures. Average aerosol composition during the studied period yielded (arithmetic mean~± standard deviation) 4.81 ± 3.05, 3.26 ± 2.10, 0.30 ± 0.27, 0.52 ± 0.32, 0.37 ± 0.21 and 0.04 ± 0.04 μg m-3 for organics, BC, NH4, SO4, NO3 and Cl, respectively. Particle number concentration was 12 813 ± 5350 cm-3, with a dominant nucleation mode. CCN concentrations were on average 1090 ± 328 and 3570 ± 1695 cm-3 at SS = 0.23% and SS = 1.13%, respectively. Results show an increase in aerosol hygroscopicity in the afternoon as a result of aerosol photochemical processing, leading to an enhancement of both organic and inorganic secondary aerosols in the atmosphere, as well as an increase in aerosol average diameter. Considering the bulk composition alone, observed CCN concentrations were substantially overpredicted when compared with the Köhler theory (44.1 ± 47.9% at 0.23% supersaturation and 91.4 ± 40.3% at 1.13% supersaturation). Overall, the impact of composition on the calculated CCN concentration (NCCN) decreases with decreasing supersaturation, partially because using bulk composition introduces less bias for large diameters and lower critical supersaturations, defined as the supersaturation at which the cloud droplet activation will take place. Results suggest that the consideration of only inorganic fraction improves the calculated NCCN. Introducing a size-dependent chemical

  18. Evaluation of the Tobacco Heating System 2.2. Part 2: Chemical composition, genotoxicity, cytotoxicity, and physical properties of the aerosol.

    PubMed

    Schaller, Jean-Pierre; Keller, Daniela; Poget, Laurent; Pratte, Pascal; Kaelin, Etienne; McHugh, Damian; Cudazzo, Gianluca; Smart, Daniel; Tricker, Anthony R; Gautier, Lydia; Yerly, Michel; Reis Pires, Roger; Le Bouhellec, Soazig; Ghosh, David; Hofer, Iris; Garcia, Eva; Vanscheeuwijck, Patrick; Maeder, Serge

    2016-11-30

    The chemical composition, in vitro genotoxicity, and cytotoxicity of the mainstream aerosol from the Tobacco Heating System 2.2 (THS2.2) were compared with those of the mainstream smoke from the 3R4F reference cigarette. In contrast to the 3R4F, the tobacco plug in the THS2.2 is not burnt. The low operating temperature of THS2.2 caused distinct shifts in the aerosol composition compared with 3R4F. This resulted in a reduction of more than 90% for the majority of the analyzed harmful and potentially harmful constituents (HPHCs), while the mass median aerodynamic diameter of the aerosol remained similar. A reduction of about 90% was also observed when comparing the cytotoxicity determined by the neutral red uptake assay and the mutagenic potency in the mouse lymphoma assay. The THS2.2 aerosol was not mutagenic in the Ames assay. The chemical composition of the THS2.2 aerosol was also evaluated under extreme climatic and puffing conditions. When generating the THS2.2 aerosol under "desert" or "tropical" conditions, the generation of HPHCs was not significantly modified. When using puffing regimens that were more intense than the standard Health Canada Intense (HCI) machine-smoking conditions, the HPHC yields remained lower than when smoking the 3R4F reference cigarette with the HCI regimen.

  19. Aerosol chemical composition and light scattering during a winter season in Beijing

    NASA Astrophysics Data System (ADS)

    Tao, Jun; Zhang, Leiming; Gao, Jian; Wang, Han; Chai, Faihe; Wang, Shulan

    2015-06-01

    To evaluate PM2.5 contributions to light scattering under different air pollution levels, PM2.5 and its major chemical components, PM10, size-segregated water-soluble ions, and aerosol scattering coefficient (bsp) under dry conditions were measured at an urban site in Beijing in January 2013 when heavy pollution events frequently occurred. Measurements were categorized into three pollution levels including heavy-polluted (Air Quality Index (AQI) ≥ 200), light-polluted (200 > AQI ≥ 100) and clean periods (AQI < 100). The average PM2.5 mass concentration was 248 μg m-3 during the heavy-polluted period, which was 2.4 and 5.6 times of those during the light-polluted (104 μg m-3) and clean (44 μg m-3) periods, respectively. The concentrations of SO42-, NO3- and NH4+ increased much more than those of OC and EC during the heavy-polluted period compared with those during the light-polluted and clean periods. Good correlations between PM2.5 and bsp were found (R2 > 0.95) during the different pollution levels. The mass scattering efficiency (MSE) of PM2.5 was 4.9 m2 g-1 during the heavy-polluted period, which was higher than those during the light-polluted (4.3 m2 g-1) and clean periods (3.6 m2 g-1). To further evaluate the impact of individual chemical components of PM2.5 on light scattering, a multiple linear regression equation of measured bsp against the mass concentration of (NH4)2SO4, NH4NO3, Organic Matter (OM), EC, Fine Soil (FS), Coarse Matter (CM) and Other chemical compounds were performed. (NH4)2SO4, NH4NO3 and OM were the dominant species contributing to bsp under both dry and ambient conditions. OM contributed more to bsp than the sum of (NH4)2SO4 and NH4NO3 did under the dry condition during all the pollution periods and this was also the case under the ambient condition during the light-polluted and clean periods. However, the total contributions of (NH4)2SO4 and NH4NO3 to bsp under the ambient condition was 55%, much more than the 29% contribution

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

    SciTech Connect

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

    1994-01-20

    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 US-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 {open_quotes}background{close_quotes} 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 troposphere/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. 71 refs., 5 figs., 5 tabs.

  1. Intercomparisons of Airborne Measurements of Aerosol Ionic Chemical Composition during TRACE-P and ACE-Asia

    NASA Technical Reports Server (NTRS)

    Ma, Y.; Weber, R. J.; Maxwell-Meier, K.; Orsini, D. A.; Lee, Y.-N.; Huebert, B. J.; Howell, S. G.; Bertram, T.; Talbot, R. W.

    2003-01-01

    As part of the two field studies, Transport and Chemical Evolution over the Pacific (TRACE-P), and the Asian Aerosol Characterization Experiment (ACEAsia), the inorganic chemical composition of tropospheric aerosols was measured over the western Pacific from three separate aircraft using various methods. Comparisons are made between the rapid online techniques of the Particle Into Liquid Sampler (PILS) for measurement of a suite of fine particle ionic compounds and a mist chamber (MC/IC) measurement of fine sulfate, and the longer time-integrated filter and multi-orifice impactor (MOI) measurements. Comparisons between identical PILS on two separate aircraft flying in formation showed that they were highly correlated (e.g., sulfate r(sup 2) of 0.95), but were systematically different by 10 +/- 5% (linear regression slope and 95% confidence bounds), and had generally higher concentrations on the aircraft with a low turbulence inlet and shorter inlet-to-instrument transmission tubing. Comparisons of PILS and mist chamber measurements of fine sulfate on two different aircraft during formation flying had an 3 of 0.78 and a relative difference of 39% +/- 5%. MOI ionic data integrated to the PILS upper measurement size of 1.3 pm sampling from separate inlets on the same aircraft showed that for sulfate, PILS and MOI were within 14% +/- 6% and correlated with an r(sup 2) of 0.87. Most ionic compounds were within f 30%, which is in the range of differences reported between PILS and integrated samplers from ground-based comparisons. In many cases, direct intercomparison between the various instruments is difficult due to differences in upper-size detection limits. However, for this study, the results suggest that the fine particle mass composition measured from aircraft agree to within 30-40%.

  2. Real-Time Investigation of Chemical Compositions and Hygroscopic Properties of Aerosols Generated from NaCl and Malonic Acid Mixture Solutions Using in Situ Raman Microspectrometry.

    PubMed

    Li, Xue; Gupta, Dhrubajyoti; Lee, Jisoo; Park, Geonhee; Ro, Chul-Un

    2017-01-03

    Recently, ambient sea spray aerosols (SSAs) have been reported to undergo reactions with dicarboxylic acids (DCAs). Several studies have examined the hygroscopic behavior and chemical reactivity of aerosols generated from NaCl-DCA mixture solutions, but the results have varied, especially for the NaCl-malonic acid (NaCl-MA) mixture system. In this work, in situ Raman microspectrometry (RMS) was used to simultaneously monitor the change in chemical composition, size, and phase as a function of the relative humidity, for individual aerosols generated from NaCl-MA solutions, during two hygroscopic measurement cycles, which were performed first through the dehydration process, followed by a humidification process, in each cycle. In situ RMS analysis for the aerosols showed that the chemical reaction between NaCl and MA occurred rapidly in the time scale of 1 h and considerably in the aqueous phase, mostly during the first dehydration process, and the chemical reaction occurs more rapidly when MA is more enriched in the aerosols. For example, the reaction between NaCl and MA for aerosols generated from solutions of NaCl:MA = 2:1 and 1:2 occurred by 81% and 100% at RH = 42% and 45%, respectively, during the first dehydration process. The aerosols generated from the solution of NaCl:MA = 2:1 revealed single efflorescence and deliquescence transitions repeatedly during two hygroscopic cycles. The aerosols from NaCl:MA = 1:1 and 1:2 solutions showed just an efflorescence transition during the first dehydration process and no efflorescence and deliquescence transition during the hygroscopic cycles, respectively. The observed different hygroscopic behavior was due to the different contents of NaCl, MA, and monosodium malonate in the aerosols, which were monitored real-time by in situ RMS.

  3. Saharan dust aerosol over the central Mediterranean Sea: PM10 chemical composition and concentration versus optical columnar measurements

    NASA Astrophysics Data System (ADS)

    Marconi, M.; Sferlazzo, D. M.; Becagli, S.; Bommarito, C.; Calzolai, G.; Chiari, M.; di Sarra, A.; Ghedini, C.; Gómez-Amo, J. L.; Lucarelli, F.; Meloni, D.; Monteleone, F.; Nava, S.; Pace, G.; Piacentino, S.; Rugi, F.; Severi, M.; Traversi, R.; Udisti, R.

    2014-02-01

    This study aims to determine the mineral contribution to PM10 in the central Mediterranean Sea, based on 7 yr of daily PM10 samplings made on the island of Lampedusa (35.5° N, 12.6° E). The chemical composition of the PM10 samples was determined by ion chromatography for the main ions, and, on selected samples, by particle-induced X-ray emission (PIXE) for the total content of crustal markers. Aerosol optical depth measurements were carried out in parallel to the PM10 sampling. The average PM10 concentration at Lampedusa over the period June 2004-December 2010 is 31.5 μg m-3, with low interannual variability. The annual means are below the EU annual standard for PM10, but 9.9% of the total number of daily data exceeds the daily threshold value established by the European Commission for PM (50 μg m-3, European Community, EC/30/1999). The Saharan dust contribution to PM10 was derived by calculating the contribution of Al, Si, Fe, Ti, non-sea-salt (nss) Ca, nssNa, and nssK oxides in samples in which PIXE data were available. Cases in which crustal content exceeded the 75th percentile of the crustal oxide content distribution were identified as elevated dust events. Using this threshold, we obtained 175 events. Fifty-five elevated dust events (31.6%) displayed PM10 higher than 50 μg m-3, with dust contributing by 33% on average. The crustal contribution to PM10 has an annual average value of 5.42 μg m-3, and reaches a value as high as 67.9 μg m-3 (corresponding to 49% of PM10) during an intense Saharan dust event. The crustal content estimated from a single tracer, such as Al or Ca, is in good agreement with the one calculated as the sum of the metal oxides. Conversely, larger crustal contents are derived by applying the EU guidelines for demonstration and subtraction of exceedances in PM10 levels due to high background of natural aerosol. The crustal aerosol amount and contribution to PM10 showed a very small seasonal dependence; conversely, the dust columnar

  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. Aerosol single scattering albedo affected by chemical composition: An investigation using CRDS combined with MARGA

    NASA Astrophysics Data System (ADS)

    Li, Ling; Chen, Jianmin; Wang, Lin; Melluki, Wahid; Zhou, Hourong

    2013-04-01

    This work describes a field measurement of the aerosol optical properties and water-soluble inorganic (WSI) ion concentrations in aerosols at 1 h resolution from 2 April to 5 May 2010 in urban Shanghai. The average scattering coefficient at 532 nm (αs,532) is 102 ± 75 Mm- 1, much lower than values of Beijng and Guangzhou although four pollution events occurred during this field campaign. The single scattering albedo (ω) is 0.70 at 532 nm, which is considerably low, indicating higher relative abundance of light absorbing soot in Shanghai. The similar patterns of diurnal cycles of αs,532 and NH4+ concentration suggested that formation of secondary inorganic aerosol is one of dominant elements to decide diurnal cycles of optical properties of aerosol in Shanghai. Both αs,532 and absorption coefficient at 532 nm (αa,532) have linear relationship with mass concentration of SO42 -, NO3-, Cl- and NH4+. The concentration of NH4+ presents best linear relationship with αs,532. The mass scattering cross section is 15.7 m2 g- 1 for SO42 -. There is obvious dependence between the aerosol optical properties and the wind directions. The aerosol loading from west is much higher than those from Northeast (NE) and Southeast (SE) due to pollution parcels from Zhejiang and Jiangsu province. The decreasing rate of ω following the increase of αa,532 is highest during NE wind period, followed by that during SE and then West, suggesting a higher mass fraction of soot in aerosol during NE wind.

  6. 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

  7. Chemical composition and aerosol size distribution of the middle mountain range in the Nepal Himalayas during the 2009 pre-monsoon season

    NASA Astrophysics Data System (ADS)

    Shrestha, P.; Barros, A. P.; Khlystov, A.

    2010-12-01

    Aerosol particle number size distribution and chemical composition were measured at two low altitude sites, one urban and one relatively pristine valley, in Central Nepal during the 2009 pre-monsoon season (May-June). This is the first time that aerosol size distribution and chemical composition were measured simultaneously at lower elevations in the middle Himalayan region in Nepal. The aerosol size distribution was measured using a Scanning Mobility Particle Sizer (SMPS, 14-340 nm), and the chemical composition of the filter samples collected during the field campaign was analyzed in the laboratory. Teflon membrane filters were used for ion chromatography (IC) and water-soluble organic carbon and nitrogen analysis. Quartz fiber filters were used for organic carbon and elemental carbon analysis. Multi-lognormal fits to the measured aerosol size distribution indicated a consistent larger mode around 100 nm which is usually the oldest, most processed background aerosol. The smaller mode was located around 20 nm, which is indicative of fresh but not necessarily local aerosol. The diurnal cycle of the aerosol number concentration showed the presence of two peaks (early morning and evening), during the transitional periods of boundary layer growth and collapse. The increase in number concentration during the peak periods was observed for the entire size distribution. Although the possible contribution of local emissions in size ranges similar to the larger mode cannot be completely ruled out, another plausible explanation is the mixing of aged elevated aerosol in the residual layer during the morning period as suggested by previous studies. Similarly, the evening time concentration peaks when the boundary layer becomes shallow concurrent with increase in local activity. A decrease in aerosol number concentration was observed during the nighttime with the development of cold (downslope) mountain winds that force the low level warmer air in the valley to rise. The

  8. Production Mechanisms, Number Concentration, Size Distribution. Chemical Composition, and Optical Properties of Sea Spray Aerosols

    NASA Technical Reports Server (NTRS)

    Meskhidze, Nicholas; Petters, Markus; Tsigaridis, Kostas; Bates. Tim; O'Dowd, Colin; Reid, Jeff; Lewis, Ernie R.; Gantt, Brett; Anguelova, Magdalena D.; Bhave, Prakash V.; Bird, James; Callaghan, Adrian H.; Ceburnis, Darius; Chang, Rachel; Clark, Antony; deLeeuw, Gerrit; Deane, Grant; DeMott, Paul J.; Elliot, Scott; Facchini, Maria Cristina; Fairall, Chris W.; Hawkins, Lelia; Hu, Yongxiang; Smirnov, Alexander

    2013-01-01

    Over forty scientists from six countries convened in Raleigh, NC on June 4-6 2012 to review the status and prospects of sea spray aerosol research. Participants were researchers from the oceanography and atmospheric science communities, including academia, private industry, and government agencies. The recommendations from the working groups are summarized in a science prioritization matrix that is meant to prioritize the research agenda and identify areas of investigation by the magnitude of their impact on proposed science questions. Str

  9. Analysis of the chemical and physical properties of combustion aerosols: Properties overview

    EPA Science Inventory

    Aerosol chemical composition is remarkably complex. Combustion aerosols can comprise tens of thousands of organic compounds and fragments, refractory carbon, metals, cations, anions, salts, and other inorganic phases and substituents [Hays et al., 2004]. Aerosol organic matter no...

  10. Characterization of the Chemical Composition of TITAN'S Aerosols Analogues with a Systematic Pyrolysis-GCMS Analysis Approach

    NASA Astrophysics Data System (ADS)

    Szopa, C.; Morisson, M.; Carrasco, N.; Buch, A.; Gautier, T.

    2014-12-01

    Pyrolysis coupled to gas chromatography-mass spectrometry is used for long to characterize the chemical composition and structure of analogues of Titan's aerosols (tholins). However, a review of the characterizations of tholins done for 30 years with this technique show that the nature of the tholins were quite different in the different studies, and the analytical conditions used for Pyr-GCMS analysis were generally very limited. The differences observed in the results obtained in these different studies are therefore difficult to attribute either to the process used to produce the tholins, or to the analytical conditions used. These are the reasons we performed a systematic study on tholins produced uniquely with the PAMPRE laboratory experiment based on a RF cold plasma, to determine the composition and structure of these analogues of Titan's aerosols, and to estimate the difference of properties induced by a variation of the content of CH4 in the initial gaseous mixture. To take the whole benefit of the pyr-GCMS technique, we performed analyses of tholins by studying the influence of all the analytical parameters. Among the main parameters, we studied : the influence of the temperature of pyrolysis on the nature of the gaseous compounds released by the solid tholins; the program of temperature used to heat the GC column in order to find a tradeoff for the analysis of both the lightest and heaviest compounds released by the sample; the separation of the same pyrolysates with two different columns. Moreover, the identification of numerous isomers was confirmed using analytical standards. WIth this study, we managed to strictly characterize a wide range of pyrolyzates for the three tholins sample studied. Most of these species are nitrogen bearing organics of various natures. More than the detection of pyrolyzates which have never been reported in previous studies, we showed that even if numerous pyrolysates were common between the three types of tholins studied

  11. Measurements of the Size-Resolved Chemical Composition of Marine Boundary Layer Aerosols in Asian Outflow During the ACE-Asia Campaign

    NASA Astrophysics Data System (ADS)

    Guazzotti, S. A.; Sodeman, D. A.; Moffet, R.; Prather, K. A.

    2003-12-01

    The size and chemical composition of individual particles were evaluated with high temporal resolution during the Asian Pacific Regional Aerosol Chemical Characterization Experiment (ACE-Asia) using a transportable aerosol time-of-flight mass spectrometer (ATOFMS) aboard the NOAA Research Vessel Ronald H. Brown. ATOFMS allows characterization of the aerodynamic diameter and chemical composition of individual particles from a polydisperse aerosol. This technique couples aerodynamic particle sizing with time-of-flight mass spectrometry in a single instrument, providing both positive and negative ion mass spectra for each detected particle which are employed to classify the particles into different classes using criteria based searches and a neural network algorithm, ART-2a. Size-resolved chemical characteristics of sampled particles under different synoptic meteorological patterns and at various locations and distances from continental influences are discussed in detail, with special focus given to the associations among different species and the variability in the degrees of aging, reaction, and/or mixing, which can alter the optical properties of these particles. Changes in the aerosol chemical characteristics due to heterogeneous reactions are evidenced in the mass spectra of detected particles by the presence and intensity of specific ion markers (e.g., sulfate, nitrate). The ability to differentiate between particles that have undergone heterogeneous reactions is relevant since these reactions affect several aerosol attributes, such as hygroscopic, optical, and radiative properties. Particularly, heterogeneous reactions/ nucleation on sea-salt and dust particles are discussed together with results of comparison efforts with some relevant laboratory and source characterization studies that allow determination of corresponding ion markers, relative ratios among species, and probable sources from a single particle perspective.

  12. Wintertime aerosol chemical composition and source apportionment of the organic fraction in the metropolitan area of Paris

    NASA Astrophysics Data System (ADS)

    Crippa, M.; DeCarlo, P. F.; Slowik, J. G.; Mohr, C.; Heringa, M. F.; Chirico, R.; Poulain, L.; Freutel, F.; Sciare, J.; Cozic, J.; Di Marco, C. F.; Elsasser, M.; Nicolas, J. B.; Marchand, N.; Abidi, E.; Wiedensohler, A.; Drewnick, F.; Schneider, J.; Borrmann, S.; Nemitz, E.; Zimmermann, R.; Jaffrezo, J.-L.; Prévôt, A. S. H.; Baltensperger, U.

    2013-01-01

    The effect of a post-industrial megacity on local and regional air quality was assessed via a month-long field measurement campaign in the Paris metropolitan area during winter 2010. Here we present source apportionment results from three aerosol mass spectrometers and two aethalometers deployed at three measurement stations within the Paris region. Submicron aerosol composition is dominated by the organic fraction (30-36%) and nitrate (28-29%), with lower contributions from sulfate (14-16%), ammonium (12-14%) and black carbon (7-13%). Organic source apportionment was performed using positive matrix factorization, resulting in a set of organic factors corresponding both to primary emission sources and secondary production. The dominant primary sources are traffic (11-15% of organic mass), biomass burning (13-15%) and cooking (up to 35% during meal hours). Secondary organic aerosol contributes more than 50% to the total organic mass and includes a highly oxidized factor from indeterminate and/or diverse sources and a less oxidized factor related to wood burning emissions. Black carbon was apportioned to traffic and wood burning sources using a model based on wavelength-dependent light absorption of these two combustion sources. The time series of organic and black carbon factors from related sources were strongly correlated. The similarities in aerosol composition, total mass and temporal variation between the three sites suggest that particulate pollution in Paris is dominated by regional factors, and that the emissions from Paris itself have a relatively low impact on its surroundings.

  13. 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.

  14. 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.

  15. Saharan dust aerosol over the central Mediterranean Sea: optical columnar measurements vs. aerosol load, chemical composition and marker solubility at ground level

    NASA Astrophysics Data System (ADS)

    Marconi, M.; Sferlazzo, D. M.; Becagli, S.; Bommarito, C.; Calzolai, G.; Chiari, M.; di Sarra, A.; Ghedini, C.; Gómez-Amo, J. L.; Lucarelli, F.; Meloni, D.; Monteleone, F.; Nava, S.; Pace, G.; Piacentino, S.; Rugi, F.; Severi, M.; Traversi, R.; Udisti, R.

    2013-08-01

    This study aims at the determination of the mineral contribution to PM10 in the central Mediterranean Sea on the basis of 7 yr of PM10 chemical composition daily measurements made on the island of Lampedusa (35.5° N, 12.6° E). Aerosol optical depth measurements are carried out in parallel while sampling with a multi-stage impactor, and observations with an optical particle counter were performed in selected periods. Based on daily samples, the total content and soluble fraction of selected metals are used to identify and characterize the dust events. The total contribution is determined by PIXE (particle-induced X-ray emission) while the composition of the soluble fraction by ICP-AES (inductively coupled plasma atomic emission spectroscopy) after extraction with HNO3 at pH 1.5. The average PM10 concentration at Lampedusa calculated over the period June 2004-December 2010 is 31.5 μg m-3, with low interannual variability. The annual means are below the EU annual standard for PM10, but 9.9% of the total number of daily data exceed the daily threshold value established by the European Commission for PM (50 μg m-3, European Community, EC/30/1999). The Saharan dust contribution to PM10 was derived by calculating the contribution of Al, Si, Fe, Ti, non-sea-salt (nss) Ca, nssNa, and nssK oxides in samples in which PIXE data were available. Cases with crustal content exceeding the 75th percentile of the crustal oxide content distribution were identified as dust events. Using this threshold we identify 175 events; 31.6% of them (55 events) present PM10 higher than 50 μg m-3, with dust contributing by 33% on average. The annual average crustal contribution to PM10 is 5.42 μg m-3, reaching a value as high as 67.9 μg m-3, 49% of PM10, during an intense Saharan dust event. The crustal aerosol amount and contribution to PM10 shows a very small seasonal dependence; conversely, the dust columnar burden displays an evident annual cycle, with a strong summer maximum (monthly

  16. 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.

  17. Comparison between simulated and observed chemical composition of fine aerosols in Paris (France) during springtime: contribution of regional versus continental emissions

    NASA Astrophysics Data System (ADS)

    Sciare, J.; D'Argouges, O.; Sarda-Estève, R.; Gaimoz, C.; Gros, V.; Zhang, Q. J.; Beekmann, M.; Sanchez, O.

    2010-07-01

    Hourly concentrations of inorganic salts (ions) and carbonaceous material in fine aerosols (aerodynamic diameter, A.D.<2.5 μm) have been determined experimentally from fast measurements performed for a 3-week period in spring 2007 in Paris (France). The sum of these two chemical components (ions and carbonaceous aerosols) has shown to account for most of the fine aerosol mass (PM2.5). This time-resolved dataset allowed investigating the factors controlling the levels of PM2.5 in Paris and showed that polluted periods with PM2.5<15 μg/m3 were characterized by air masses of continental (North-Western Europe) origin and chemical composition made by 75% of ions. By contrast, periods with clean marine air masses have shown the lowest PM2.5 concentrations (typically of about 10 μg/m3); carbonaceous aerosols contributing for most of this mass (typically 75%). In order to better discriminate between regional and continental contributions to the observed chemical composition and concentrations of PM2.5 over Paris, a comparative study was performed between this time-resolved dataset and the outputs of a chemistry transport model (CHIMERE), showing a relatively good capability of the model to reproduce the time-limited intense maxima observed in the field for PM2.5 and ion species. Different model scenarios were then investigated switching off regional and European (North-Western and Central) emissions. Results of these scenarios have clearly shown that most of the ions observed over Paris during polluted periods, were either transported or formed in-situ from gas precursors transported from Northern Europe. By opposite, long-range transport from Europe appeared to poorly contribute to the levels of carbonaceous aerosols observed over Paris. The model failed to properly account for the concentration levels and variability of secondary organic aerosols (SOA) determined experimentally by the EC-tracer method. The abundance of SOA (relatively to organic aerosol, OA) was as

  18. Comparison between simulated and observed chemical composition of fine aerosols in Paris (France) during springtime: contribution of regional versus continental emissions

    NASA Astrophysics Data System (ADS)

    Sciare, J.; D'Argouges, O.; Zhang, Q. J.; Sarda-Estève, R.; Gaimoz, C.; Gros, V.; Beekmann, M.; Sanchez, O.

    2010-12-01

    Hourly concentrations of inorganic salts (ions) and carbonaceous material in fine aerosols (aerodynamic diameter, A.D. <2.5 μm) have been determined experimentally from fast measurements performed for a 3-week period in spring 2007 in Paris (France). The sum of these two chemical components (ions and carbonaceous aerosols) has shown to account for most of the fine aerosol mass (PM2.5). This time-resolved dataset allowed investigating the factors controlling the levels of PM2.5 in Paris and showed that polluted periods with PM2.5 > 15 μg m-3 were characterized by air masses of continental (North-Western Europe) origin and chemical composition made by 75% of ions. By contrast, periods with clean marine air masses have shown the lowest PM2.5 concentrations (typically of about 10 μg m-3); carbonaceous aerosols contributing for most of this mass (typically 75%). In order to better discriminate between local and continental contributions to the observed chemical composition and concentrations of PM2.5 over Paris, a comparative study was performed between this time-resolved dataset and the outputs of a chemistry transport model (CHIMERE), showing a relatively good capability of the model to reproduce the time-limited intense maxima observed in the field for PM2.5 and ion species. Different model scenarios were then investigated switching off local and European (North-Western and Central) emissions. Results of these scenarios have clearly shown that most of the ions observed over Paris during polluted periods, were either transported or formed in-situ from gas precursors transported from Northern Europe. On the opposite, long-range transport from Europe appeared to weakly contribute to the levels of carbonaceous aerosols observed over Paris. The model failed to properly account for the concentration levels and variability of secondary organic aerosols (SOA) determined experimentally by the EC-tracer method. The abundance of SOA (relatively to organic aerosol, OA) was as

  19. Complex chemical composition of colored surface films formed from reactions of propanal in sulfuric acid at upper troposphere/lower stratosphere aerosol acidities

    NASA Astrophysics Data System (ADS)

    Van Wyngarden, A. L.; Pérez-Montaño, S.; Bui, J. V. H.; Li, E. S. W.; Nelson, T. E.; Ha, K. T.; Leong, L.; Iraci, L. T.

    2015-04-01

    Particles in the upper troposphere and lower stratosphere (UT/LS) consist mostly of concentrated sulfuric acid (40-80 wt%) in water. However, airborne measurements have shown that these particles also contain a significant fraction of organic compounds of unknown chemical composition. Acid-catalyzed reactions of carbonyl species are believed to be responsible for significant transfer of gas phase organic species into tropospheric aerosols and are potentially more important at the high acidities characteristic of UT/LS particles. In this study, experiments combining sulfuric acid (H2SO4) with propanal and with mixtures of propanal with glyoxal and/or methylglyoxal at acidities typical of UT/LS aerosols produced highly colored surface films (and solutions) that may have implications for aerosol properties. In order to identify the chemical processes responsible for the formation of the surface films, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) and 1H nuclear magnetic resonance (NMR) spectroscopies were used to analyze the chemical composition of the films. Films formed from propanal were a complex mixture of aldol condensation products, acetals and propanal itself. The major aldol condensation products were the dimer (2-methyl-2-pentenal) and 1,3,5-trimethylbenzene that was formed by cyclization of the linear aldol condensation trimer. Additionally, the strong visible absorption of the films indicates that higher-order aldol condensation products must also be present as minor species. The major acetal species were 2,4,6-triethyl-1,3,5-trioxane and longer-chain linear polyacetals which are likely to separate from the aqueous phase. Films formed on mixtures of propanal with glyoxal and/or methylglyoxal also showed evidence of products of cross-reactions. Since cross-reactions would be more likely than self-reactions under atmospheric conditions, similar reactions of aldehydes like propanal with common aerosol organic species like glyoxal and

  20. Complex chemical composition of colored surface films formed from reactions of propanal in sulfuric acid at upper troposphere/lower stratosphere aerosol acidities

    NASA Astrophysics Data System (ADS)

    Van Wyngarden, A. L.; Pérez-Montaño, S.; Bui, J. V. H.; Li, E. S. W.; Nelson, T. E.; Ha, K. T.; Leong, L.; Iraci, L. T.

    2014-11-01

    Particles in the upper troposphere and lower stratosphere (UT/LS) consist mostly of concentrated sulfuric acid (40-80 wt %) in water. However, airborne measurements have shown that these particles also contain a significant fraction of organic compounds of unknown chemical composition. Acid-catalyzed reactions of carbonyl species are believed to be responsible for significant transfer of gas phase organic species into tropospheric aerosols and are potentially more important at the high acidities characteristic of UT/LS particles. In this study, experiments combining sulfuric acid (H2SO4) with propanal and with mixtures of propanal with glyoxal and/or methylglyoxal at acidities typical of UT/LS aerosols produced highly colored surface films (and solutions) that may have implications for aerosol properties. In order to identify the chemical processes responsible for the formation of the surface films, Attenuated Total Reflectance-Fourier Transform Infrared and 1H Nuclear Magnetic Resonance spectroscopies were used to analyze the chemical composition of the films. Films formed from propanal were a complex mixture of aldol condensation products, acetals and propanal itself. The major aldol condensation products were the dimer (2-methyl-2-pentenal) and 1,3,5-trimethylbenzene, which was formed by cyclization of the linear aldol condensation trimer. Additionally, the strong visible absorption of the films indicates that higher order aldol condensation products must also be present as minor species. The major acetal species were 2,4,6-triethyl-1,3,5-trioxane and longer-chain linear polyacetals which are likely to separate from the aqueous phase. Films formed on mixtures of propanal with glyoxal and/or methylglyoxal also showed evidence for products of cross-reactions. Since cross-reactions would be more likely than self-reactions under atmospheric conditions, similar reactions of aldehydes like propanal with common aerosol organic species like glyoxal and methylglyoxal

  1. Complex chemical composition of colored surface films formed from reactions of propanal in sulfuric acid at upper troposphere/lower stratosphere aerosol acidities

    PubMed Central

    Van Wyngarden, A. L.; Pérez-Montaño, S.; Bui, J. V. H.; Li, E. S. W.; Nelson, T. E.; Ha, K. T.; Leong, L.; Iraci, L. T.

    2016-01-01

    Particles in the upper troposphere and lower stratosphere (UT/LS) consist mostly of concentrated sulfuric acid (40–80 wt %) in water. However, airborne measurements have shown that these particles also contain a significant fraction of organic compounds of unknown chemical composition. Acid-catalyzed reactions of carbonyl species are believed to be responsible for significant transfer of gas phase organic species into tropospheric aerosols and are potentially more important at the high acidities characteristic of UT/LS particles. In this study, experiments combining sulfuric acid (H2SO4) with propanal and with mixtures of propanal with glyoxal and/or methylglyoxal at acidities typical of UT/LS aerosols produced highly colored surface films (and solutions) that may have implications for aerosol properties. In order to identify the chemical processes responsible for the formation of the surface films, attenuated total reflectance–Fourier transform infrared (ATR-FTIR) and 1H nuclear magnetic resonance (NMR) spectroscopies were used to analyze the chemical composition of the films. Films formed from propanal were a complex mixture of aldol condensation products, acetals and propanal itself. The major aldol condensation products were the dimer (2-methyl-2-pentenal) and 1,3,5-trimethylbenzene that was formed by cyclization of the linear aldol condensation trimer. Additionally, the strong visible absorption of the films indicates that higher-order aldol condensation products must also be present as minor species. The major acetal species were 2,4,6-triethyl-1,3,5-trioxane and longer-chain linear polyacetals which are likely to separate from the aqueous phase. Films formed on mixtures of propanal with glyoxal and/or methylglyoxal also showed evidence of products of cross-reactions. Since cross-reactions would be more likely than self-reactions under atmospheric conditions, similar reactions of aldehydes like propanal with common aerosol organic species like glyoxal and

  2. Complex chemical composition of colored surface films formed from reactions of propanal in sulfuric acid at upper troposphere/lower stratosphere aerosol acidities.

    PubMed

    Van Wyngarden, A L; Pérez-Montaño, S; Bui, J V H; Li, E S W; Nelson, T E; Ha, K T; Leong, L; Iraci, L T

    Particles in the upper troposphere and lower stratosphere (UT/LS) consist mostly of concentrated sulfuric acid (40-80 wt %) in water. However, airborne measurements have shown that these particles also contain a significant fraction of organic compounds of unknown chemical composition. Acid-catalyzed reactions of carbonyl species are believed to be responsible for significant transfer of gas phase organic species into tropospheric aerosols and are potentially more important at the high acidities characteristic of UT/LS particles. In this study, experiments combining sulfuric acid (H2SO4) with propanal and with mixtures of propanal with glyoxal and/or methylglyoxal at acidities typical of UT/LS aerosols produced highly colored surface films (and solutions) that may have implications for aerosol properties. In order to identify the chemical processes responsible for the formation of the surface films, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) and (1)H nuclear magnetic resonance (NMR) spectroscopies were used to analyze the chemical composition of the films. Films formed from propanal were a complex mixture of aldol condensation products, acetals and propanal itself. The major aldol condensation products were the dimer (2-methyl-2-pentenal) and 1,3,5-trimethylbenzene that was formed by cyclization of the linear aldol condensation trimer. Additionally, the strong visible absorption of the films indicates that higher-order aldol condensation products must also be present as minor species. The major acetal species were 2,4,6-triethyl-1,3,5-trioxane and longer-chain linear polyacetals which are likely to separate from the aqueous phase. Films formed on mixtures of propanal with glyoxal and/or methylglyoxal also showed evidence of products of cross-reactions. Since cross-reactions would be more likely than self-reactions under atmospheric conditions, similar reactions of aldehydes like propanal with common aerosol organic species like glyoxal and

  3. 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.

  4. In-Flight Chemical Composition Observations of Aircraft Emissions using a High-Resolution Time-of-Flight Aerosol Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Ziemba, L. D.; Martin, R.; Moore, R.; Shook, M.; Thornhill, K. L., II; Winstead, E.; Anderson, B. E.

    2015-12-01

    Commercial aircraft are an important source of aerosols to the upper troposphere. The microphysical and chemical properties of these emitted aerosols govern their ability to act as ice nuclei, both in near-field contrails and for cirrus formation downstream. During the ACCESS-II (Alternative Fuel Effects on Contrails and Cruise Emissions) campaign, NASA DC-8 CFM56-2-C1 engine emissions were sampled systematically at a range of cruise-relevant thrust levels and at several altitudes. Sampling was done aboard the NASA HU-25 Falcon aircraft, which was equipped with a suite of aerosol and gas-phase instruments focused on assessing the effects of burning different fuel mixtures on aerosol properties and their associated contrails. Here we present in-flight measurements of particle chemical composition made by a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS). The AMS was able to sufficiently resolve near-field (within 100m) aircraft emissions plumes. Low-sulfur HEFA (hydro-processed esters and fatty-acids) and JetA fuels yielded particles that contained 11 and 8% sulfate, respectively, compared to 30% sulfate contribution for traditional JetA fuel. Each of the fuels produced organic aerosol with similarly low oxygen content. Lubrication oils, which are not a combustion product but result from leaks in the engine, were likely a dominant fraction of the measured organic mass based on mass-spectral marker analysis. These results are compared to similar engine conditions from ground-based testing.

  5. Chemical composition and sources of ambient aerosol in an urban environment over Athens, Greece: Case study on the role of wintertime biomass burning

    NASA Astrophysics Data System (ADS)

    Theodosi, Christina

    2016-04-01

    This study examines the chemical composition of aerosols over the Greater Athens Area (GAA). To achieve this, particulate matter sampling has been conducted on a 6h-24h basis and more than 700 aerosol samples were collected at downtown Athens, in Thissio from January 2013 to December 2015. All samples, after mass quantification, were analyzed for major anions (Cl^-, Br^-, NO{_3^-}, SO{_4-2}, PO{_4-3}, C_2O{_4-2}), cations (NH{_4^+}, K^+, Na^+, Mg+2, Ca+2), trace elements (Al, As, Ca, Cd, Co, Cr, Cu, Fe, V, Zn, Mn, Ni, Pb, P, S, Sb), organic carbon (OC) and elemental carbon (EC). Aerosol chemical mass closure calculations indicated that carbonaceous aerosol constitutes a major component, along with nitrate and sulfate anions, dust, cations and EC. Moreover, during the winter periods of December 2012-January 2013 and December 2013-January 2014, air pollution due to excessive use of biomass for domestic heating has been reported as a major environmental problem in the area. To assess the importance of biomass burning as a source of air pollution over the GAA three main sugars specific biomass burning tracers (levoglucosan, mannosan and galactosan) and Polycyclic aromatic hydrocarbons (PAHs) were also analyzed during the winter period. Acknowledgments This work was supported by the State Scholarship Foundation ("IKY Fellowships of Excellence for Postgraduate Studies in Greece - Siemens Programme") in the framework of the Hellenic Republic-Siemens Settlement Agreement.

  6. Seasonal characterization of submicron aerosol chemical composition and organic aerosol sources in the southeastern United States: Atlanta, Georgia,and Look Rock, Tennessee

    NASA Astrophysics Data System (ADS)

    Hapsari Budisulistiorini, Sri; Baumann, Karsten; Edgerton, Eric S.; Bairai, Solomon T.; Mueller, Stephen; Shaw, Stephanie L.; Knipping, Eladio M.; Gold, Avram; Surratt, Jason D.

    2016-04-01

    A year-long near-real-time characterization of non-refractory submicron aerosol (NR-PM1) was conducted at an urban (Atlanta, Georgia, in 2012) and rural (Look Rock, Tennessee, in 2013) site in the southeastern US using the Aerodyne Aerosol Chemical Speciation Monitor (ACSM) collocated with established air-monitoring network measurements. Seasonal variations in organic aerosol (OA) and inorganic aerosol species are attributed to meteorological conditions as well as anthropogenic and biogenic emissions in this region. The highest concentrations of NR-PM1 were observed during winter and fall seasons at the urban site and during spring and summer at the rural site. Across all seasons and at both sites, NR-PM1 was composed largely of OA (up to 76 %) and sulfate (up to 31 %). Six distinct OA sources were resolved by positive matrix factorization applied to the ACSM organic mass spectral data collected from the two sites over the 1 year of near-continuous measurements at each site: hydrocarbon-like OA (HOA), biomass burning OA (BBOA), semi-volatile oxygenated OA (SV-OOA), low-volatility oxygenated OA (LV-OOA), isoprene-derived epoxydiols (IEPOX) OA (IEPOX-OA) and 91Fac (a factor dominated by a distinct ion at m/z 91 fragment ion previously observed in biogenic influenced areas). LV-OOA was observed throughout the year at both sites and contributed up to 66 % of total OA mass. HOA was observed during the entire year only at the urban site (on average 21 % of OA mass). BBOA (15-33 % of OA mass) was observed during winter and fall, likely dominated by local residential wood burning emission. Although SV-OOA contributes quite significantly ( ˜ 27 %), it was observed only at the urban site during colder seasons. IEPOX-OA was a major component (27-41 %) of OA at both sites, particularly in spring and summer. An ion fragment at m/z 75 is well correlated with the m/z 82 ion associated with the aerosol mass spectrum of IEPOX-derived secondary organic aerosol (SOA). The

  7. Influence of marine aerosols and aerotechnogenic load on chemical composition of rainwaters on small islands (ludas) of the White Sea

    NASA Astrophysics Data System (ADS)

    Gorbacheva, Tamara; Mazukhina, Svetlana; Isaeva, Ludmila; Shumilov, Oleg

    2013-04-01

    In June 2001 intensive monitoring plots were established on the island part of Kandalaksha Bay of the White Sea (the island Tonnaya Luda; 67o06'60"N; 32o24'12"E) with the installation of stationary rainwater collectors. The purpose was studying the chemical composition of rain waters in the zone of cumulative influence of marine aerosols and aerotechnogenic load. Water sampling was carried out monthly during the vegetative season of 2001 and 2002. pH of rain water was determined by potentiometric method without preliminary filtration. The samples were passed through the paper filter with the pore diameter of 1-2.5 microns, the analysis of filtrate carried out by methods of atomic emission spectrometry (K, Na) and atomic absorption spectrometry (Ca, Mg, Zn, Mn, Cu, Ni, Al, Fe), total P and P of phosphates, Si and NH4+ - by photocolorimetry, total carbon - by bichromate method, NO3-, SO42-, Cl--by ion exchange chromatography method. Balance method was chosen as a research basis to determine the interrelation of rain water organic matter and dynamics of its redistribution under the influence of natural and technogenic factors. The difference between the cations sum (including NH4+and H+) and mineral acids anions sum (SO42-, Cl-, NO3-) was identified as organic acids anions concentration (μeq l-1). The level of Na, Cl-, K, Ca, Mg, SO42-, Sr in rainwaters on the island and the remote areas is indicative of the possible influence of marine aerosols on the island part of the White Sea. The increase of Al, Cu, Ni, Cd, Co concentrations in rainwaters up to one order against the background values points to the cumulative influence of the emissions of industrial enterprises located in the region. The relative stability of pH values of rain waters during all seasons indicates to the buffer action of weak organic acids anions. The correlation analysis of ionic structure in normal concentrations has allowed us to estimate the distribution of the cationic part from the

  8. 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

  9. 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

  10. 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

  11. Detection of chemical agent aerosols

    NASA Astrophysics Data System (ADS)

    Fox, Jay A.; Ahl, Jeffrey L.; D'Amico, Francis M.; Vanderbeek, Richard G.; Moon, Raphael; Swim, Cynthia R.

    1999-05-01

    One of the major threats presented by a chemical agent attack is that of a munition exploding overhead and 'raining' aerosols which can contaminate surfaces when they impact. Since contact with these surfaces can be fatal, it is imperative to know when such an attack has taken place and the likely threat density and location. We present the results of an experiment designed to show the utility of a CO2 lidar in detecting such an attack. Testing occurred at Dugway Proving Grounds, Utah and involved the simulation of an explosive airburst chemical attack. Explosions occurred at a height of 30 m and liquid droplets from two chemicals, PEG-200 (polyethylene glycol 200) and TEP (triethylphosphate), were expelled and fell to the ground. The munition was the U.S. Army M9 Simulator, Projectile, Airburst, Liquid (SPAL) system that is designed for chemical warfare training exercises. The instrument that was used to detect the presence of the aerosols was the Laser Standoff Chemical Detector (LSCD) which is a light detection and ranging (LIDAR) system that utilizes a rapidly tunable, pulsed CO2 laser. The LIDAR scanned a horizontal path approximately 5 - 8 m above the ground in order to measure the concentration of liquid deposition. The LIDAR data were later correlated with card data to determine how well the system could predict the location and quantity of liquid deposition on the ground.

  12. Seasonal characterization of submicron aerosol chemical composition and organic aerosol sources in the southeastern United States: Atlanta, Georgia and Look Rock, Tennessee

    NASA Astrophysics Data System (ADS)

    Budisulistiorini, S. H.; Baumann, K.; Edgerton, E. S.; Bairai, S. T.; Mueller, S.; Shaw, S. L.; Knipping, E. M.; Gold, A.; Surratt, J. D.

    2015-08-01

    A yearlong near-real-time characterization of non-refractory submicron aerosol (NR-PM1) was conducted at an urban (Atlanta, Georgia) and rural (Look Rock, Tennessee) site in the southeastern US using the Aerodyne aerosol chemical speciation monitor (ACSM) collocated with established air-monitoring network measurements. Seasonal variations in organic aerosol (OA) and inorganic aerosol species are attributed to meteorological conditions as well as anthropogenic and biogenic emissions in this region. The highest concentrations of NR-PM1 were observed during winter and fall seasons at the urban site and during spring and summer at the rural site. Across all seasons and at both sites, NR-PM1 was composed largely of OA (50-76 %) and inorganic sulfate (12-31 %). Six distinct OA sources were resolved by positive matrix factorization applied to the ACSM organic mass spectral data collected from the two sites over the one year of near-continuous measurements at each site: hydrocarbon-like OA (HOA), biomass burning OA (BBOA), semi-volatile oxygenated OA (SV-OOA), low-volatility oxygenated OA (OOA), isoprene-derived epoxydiol (IEPOX) OA (IEPOX-OA), and 91Fac OA (a factor dominated by a distinct ion at m/z 91 fragment ion previously observed in biogenic influenced areas). LV-OOA was observed throughout the year at both sites and contributed 30-66 % of total OA mass. HOA was also observed during the entire year only at the urban site (15-24 % of OA mass). BBOA (15-33 % of OA mass) was observed during winter and fall, likely dominated by local residential wood burning emission. Although SV-OOA contributes quite significantly (∼ 27 %), it was observed only at the urban site during colder seasons. IEPOX-OA was a major component (27-41 %) of OA at both sites, particularly in spring and summer. An ion fragment at m/z 75 is proposed as an additional marker for IEPOX-OA, as it is shown to correlate well with the m/z 82 ion shown to be associated with the aerosol mass spectrum of

  13. 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

  14. 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.

  15. Variations in the chemical composition of the submicron aerosol and in the sources of the organic fraction at a regional background site of the Po Valley (Italy)

    NASA Astrophysics Data System (ADS)

    Bressi, Michael; Cavalli, Fabrizia; Belis, Claudio A.; Putaud, Jean-Philippe; Fröhlich, Roman; Martins dos Santos, Sebastiao; Petralia, Ettore; Prévôt, André S. H.; Berico, Massimo; Malaguti, Antonella; Canonaco, Francesco

    2016-10-01

    Fine particulate matter (PM) levels and resulting impacts on human health are in the Po Valley (Italy) among the highest in Europe. To build effective PM abatement strategies, it is necessary to characterize fine PM chemical composition, sources and atmospheric processes on long timescales (> months), with short time resolution (< day), and with particular emphasis on the predominant organic fraction. Although previous studies have been conducted in this region, none of them addressed all these aspects together. For the first time in the Po Valley, we investigate the chemical composition of nonrefractory submicron PM (NR-PM1) with a time resolution of 30 min at the regional background site of Ispra during 1 full year, using the Aerodyne Aerosol Chemical Speciation Monitor (ACSM) under the most up-to-date and stringent quality assurance protocol. The identification of the main components of the organic fraction is made using the Multilinear-Engine 2 algorithm implemented within the latest version of the SoFi toolkit. In addition, with the aim of a potential implementation of ACSM measurements in European air quality networks as a replacement of traditional filter-based techniques, parallel multiple offline analyses were carried out to assess the performance of the ACSM in the determination of PM chemical species regulated by air quality directives. The annual NR-PM1 level monitored at the study site (14.2 µg m-3) is among the highest in Europe and is even comparable to levels reported in urban areas like New York City and Tokyo. On the annual basis, submicron particles are primarily composed of organic aerosol (OA, 58 % of NR-PM1). This fraction was apportioned into oxygenated OA (OOA, 66 %), hydrocarbon-like OA (HOA, 11 % of OA) and biomass burning OA (BBOA, 23 %). Among the primary sources of OA, biomass burning (23 %) is thus bigger than fossil fuel combustion (11 %). Significant contributions of aged secondary organic aerosol (OOA) are observed throughout the

  16. Aerosol Chemical Composition in Asian Continental Outflow during the TRACE-P Campaign: Comparison with PEM-West B

    NASA Technical Reports Server (NTRS)

    Dibb, Jack E.; Talbot, Robert W.; Scheuer, Eric M.; Seid, Garry; Avery, Melody A.; Singh, Hanwant B.

    2003-01-01

    Aerosol associated soluble ions and the radionuclide tracers (7)Be and (210)Pb were quantified in 414 filter samples collected in spring 2001 from the DC-8 during the Transport and Chemical Evolution over the Pacific (TRACE-P) campaign. Binning the data into near Asia (flights from Hong Kong and Japan) and remote Pacific (all other flights) revealed large enhancements of NO3(-), SO4(-), C2O4(-), NH4(+), K(+), Mg2(+), and Ca2(+) near Asia. The boundary layer and lower troposphere were most strongly influenced by continental outflow, and the largest enhancements were seen in Ca2(+) (a dust tracer) and NO3(-) (reflecting uptake of HNO3 onto the dust). Comparing the TRACE P near Asia bin with earlier results from the same region during PEM-West B (in 1994) shows at least twofold enhancements during TRACE P in most of the ions listed above. Calcium and NO3(-) were most enhanced in this comparison as well (more than sevenfold higher in the boundary layer and threefold higher in the lower troposphere). Independent estimation of Asian emissions of gaseous precursors of the aerosol-associated ions suggest only small changes between the two missions, and precipitation fields do not suggest any significant difference in the efficiency of the primary sink, precipitation scavenging. It thus appears that with the possible exception of dust, the enhancements of aerosol-associated species during TRACE P cannot be explained by stronger sources or weaker sinks. We argue that the enhancements largely reflect the fact that TRACE P focused on characterizing Asian outflow, and thus the DC-8 was more frequently flown into regions that were influenced by well-organized flow off the continent.

  17. 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.

  18. 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

  19. Some environmental considerations relating to the interaction of the solid rocket motor exhaust with the atmosphere: Predicted chemical composition of exhaust species and predicted conditions for the formation of HCl aerosol

    NASA Technical Reports Server (NTRS)

    Rhein, R. A.

    1973-01-01

    The exhaust products of a solid rocket motor using as propellant 14% binder, 16% aluminum, and 70% (wt) ammonium perchlorate consist of hydrogen chloride, water, alumina, and other compounds. The equilibrium and some frozen compositions of the chemical species upon interaction with the atmosphere were computed. The conditions under which hydrogen chloride interacts with the water vapor in humid air to form an aerosol containing hydrochloric acid were computed for various weight ratios of air/exhaust products. These computations were also performed for the case of a combined SRM and hydrogen-oxygen rocket engine. Regimes of temperature and relative humidity where this aerosol is expected were identified. Within these regimes, the concentration of HCL in the aerosol and weight fraction of aerosol to gas phase were plotted. Hydrochloric acid aerosol formation was found to be particularly likely in cool humid weather.

  20. The chemical composition of aerosols from Wildland fires: Current state of the science and possible new directions.

    EPA Science Inventory

    Wildland fire emits a substantial quantity of aerosol to the atmosphere. These aerosols typically comprise a complex mixture of organic matter and refractory elemental or black carbon with a relatively minor contribution of inorganic matter from soils and plant micronutrients. Id...

  1. An Investigation of Aerosol Measurements from the Halogen Occultation Experiment: Validation, Size Distributions, Composition, and Relation to Other Chemical Species

    NASA Technical Reports Server (NTRS)

    Deshler, Terry; Hervig, Mark E.

    1998-01-01

    The efforts envisioned within the original proposal (accepted February 1994) and the extension of this proposal (accepted February 1997) included measurement validations, the retrieval of aerosol size distributions and distribution moments, aerosol correction studies, and investigations of polar stratospheric clouds. A majority of the results from this grant have been published. The principal results from this grant are discussed.

  2. 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

  3. 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

  4. 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

  5. Chemical characterization of secondary organic aerosol constituents from isoprene ozonolysis in the presence of acidic aerosol

    NASA Astrophysics Data System (ADS)

    Riva, Matthieu; Budisulistiorini, Sri Hapsari; Zhang, Zhenfa; Gold, Avram; Surratt, Jason D.

    2016-04-01

    Isoprene is the most abundant non-methane hydrocarbon emitted into Earth's atmosphere and is predominantly derived from terrestrial vegetation. Prior studies have focused largely on the hydroxyl (OH) radical-initiated oxidation of isoprene and have demonstrated that highly oxidized compounds, such as isoprene-derived epoxides, enhance the formation of secondary organic aerosol (SOA) through heterogeneous (multiphase) reactions on acidified sulfate aerosol. However, studies on the impact of acidified sulfate aerosol on SOA formation from isoprene ozonolysis are lacking and the current work systematically examines this reaction. SOA was generated in an indoor smog chamber from isoprene ozonolysis under dark conditions in the presence of non-acidified or acidified sulfate seed aerosol. The effect of OH radicals on SOA chemical composition was investigated using diethyl ether as an OH radical scavenger. Aerosols were collected and chemically characterized by ultra performance liquid chromatography/electrospray ionization high-resolution quadrupole time-of-flight mass spectrometry (UPLC/ESI-HR-QTOFMS) and gas chromatography/electron impact ionization-mass spectrometry (GC/EI-MS). Analysis revealed the formation of highly oxidized compounds, including organosulfates (OSs) and 2-methylterols, which were significantly enhanced in the presence of acidified sulfate seed aerosol. OSs identified in the chamber experiments were also observed and quantified in summertime fine aerosol collected from two rural locations in the southeastern United States during the 2013 Southern Oxidant and Aerosol Study (SOAS).

  6. CHEMICAL ANALYSIS METHODS FOR ATMOSPHERIC AEROSOL COMPONENTS

    EPA Science Inventory

    This chapter surveys the analytical techniques used to determine the concentrations of aerosol mass and its chemical components. The techniques surveyed include mass, major ions (sulfate, nitrate, ammonium), organic carbon, elemental carbon, and trace elements. As reported in...

  7. Towards the regulation of aerosol emissions by their potential health impact: Assessing adverse effects of aerosols from wood combustion and ship diesel engine emissions by combining comprehensive data on the chemical composition and their toxicological effects on human lung cells

    NASA Astrophysics Data System (ADS)

    Zimmermann, R.; Streibel, T.; Dittmar, G.; Kanashova, T.; Buters, J.; Öder, S.; Paur, H. R.; Dilger, M.; Weiss, C.; Harndorf, H.; Stengel, B.; Hirvonen, M. R.; Jokiniemi, J.; Hiller, K.; Sapcariu, S.; Sippula, O.; Orasche, J.; Müller, L.; Rheda, A.; Passig, J.; Radischat, C.; Czech, H.; Tiita, P.; Jalava, P.; Kasurinen, S.; Schwemer, T.; Yli-Prilä, P.; Tissari, J.; Lamberg, H.; Schnelle-Kreis, J.

    2014-12-01

    Ship engine emissions are important regarding lung and cardiovascular diseases in coastal regions worldwide. Bio mass burning is made responsible for adverse health effects in many cities and rural regions. The Virtual Helmholtz Institute-HICE (www.hice-vi.eu) addresses chemical & physical properties and health effects of anthropogenic combustion emissions. Typical lung cell responses to combustion aerosols include inflammation and apoptosis, but a molecular link with the specific chemical composition in particular of ship emissions has not been established. Through an air-liquid interface exposure system (ALI), we exposed human lung cells at-site to exhaust fumes from a ship engine running on common heavy fuel oil (HFO) and cleaner-burning diesel fuel (DF) as well as to emissions of wood combustion compliances. A special field deployable ALI-exposition system and a mobile S2-biological laboratory were developed for this study. Human alveolar basal epithelial cells (A549 etc.) are ALI-exposed to fresh, diluted (1:40-1:100) combustion aerosols and subsequently were toxicologically and molecular-biologically characterized. Advanced chemical analyses of the exhaust aerosols were combined with transcriptional, proteomic and metabolomic profiling to characterise the cellular responses. The HFO ship emissions contained high concentrations of toxic compounds (transition metals, organic toxicants) and particle masses. The cellular responses included inflammation and oxidative stress. Surprisingly, the DF ship emissions, which predominantly contain rather "pure" carbonaceous soot and much less known toxicants, induced significantly broader biological effects, affecting essential cellular pathways (e.g., mitochondrial function and intracellular transport). Therefore the use of distillate fuels for shipping (this is the current emission reduction strategy of the IMO) appears insufficient for diminishing health effects. The study suggests rather reducing the particle emissions

  8. Effects of Siberian wildfires on the chemical composition and acidity of atmospheric aerosols of remote urban, rural and background territories.

    PubMed

    Smolyakov, Boris S; Makarov, Valeriy I; Shinkorenko, Marina P; Popova, Svetlana A; Bizin, Mikhail A

    2014-05-01

    Extensive forest fires occurred during the summer of 2012 in Siberia. This work presents the influence of long-range atmospheric smoke on the aerosol properties at urban, suburban and background sites, which are located 400-800 km from the fire source. The higher levels of submicron particles (PM1), organic (OC), secondary organic (SOC) and elemental (EC) carbon were observed at all sampling sites, whereas an increase in ionic species HCOO(-), K(+), NO3(-), and Cl(-) and a decrease in pH was higher at the background and suburban sites in comparison with the urban site. Other natural and anthropogenic factors appear to be more significant for ions Ca(2+) + Mg(2+), HCO3(-), NH4(+), SO4(2-) and Na(+). The present study indicates that the impact of remote fires on the aerosol characteristics depends on their background (without fires) levels at the sampling sites.

  9. Physical and Chemical Characterization of Carbonaceous Aerosols in Korea

    NASA Astrophysics Data System (ADS)

    Choung, S.; Jin, J. S.; Hwang, G. S.; Jang, K. S.; Han, W. S.; OH, J.; Kwon, Y.

    2014-12-01

    Atmospheric aerosols have been recently paid attention more in environmental research due to their negative effects on air quality, public health, and climate change. The aerosols contain approximately >20-50% carbonaceous components such as organic carbon (OC) and black carbon (BC) (or elemental carbon [EC]) derived from organic compounds, biomass burning, and incomplete combustion of fossil fuels. The physical, chemical, and biological properties of atmospheric aerosols are strongly dependent on the carbonaceous components. In particular, the BC could significantly affect the regional air quality in the northeastern Asia, because China is one of the foremost BC emission country in the world. Previous studies have mainly focused on the quantification and source identification for carbonaceous aerosols. However, understanding of physical and chemical properties for the carbonaceous aerosols related to environmental contamination and toxicity was still incomplete due to analytical difficulties. This study is addressed to evaluate the contribution of carbonaceous aerosols to air pollution through the surface, mass spectroscopic, and electron microscopic analyses, and determination of chemical composition and structure using the air particulate matter (PM2.5 and >PM2.5) samples.

  10. Atmospheric aerosols as prebiotic chemical reactors

    PubMed Central

    Dobson, Christopher M.; Ellison, G. Barney; Tuck, Adrian F.; Vaida, Veronica

    2000-01-01

    Aerosol particles in the atmosphere have recently been found to contain a large number of chemical elements and a high content of organic material. The latter property is explicable by an inverted micelle model. The aerosol sizes with significant atmospheric lifetimes are the same as those of single-celled organisms, and they are predicted by the interplay of aerodynamic drag, surface tension, and gravity. We propose that large populations of such aerosols could have afforded an environment, by means of their ability to concentrate molecules in a wide variety of physical conditions, for key chemical transformations in the prebiotic world. We also suggest that aerosols could have been precursors to life, since it is generally agreed that the common ancestor of terrestrial life was a single-celled organism. The early steps in some of these initial transformations should be accessible to experimental investigation. PMID:11035775

  11. Fourteen months of on-line measurements of the non-refractory submicron aerosol at the Jungfraujoch (3580 m a.s.l.) - chemical composition, origins and organic aerosol sources

    NASA Astrophysics Data System (ADS)

    Fröhlich, R.; Cubison, M. J.; Slowik, J. G.; Bukowiecki, N.; Canonaco, F.; Henne, S.; Herrmann, E.; Gysel, M.; Steinbacher, M.; Baltensperger, U.; Prévôt, A. S. H.

    2015-07-01

    Chemically resolved (organic, nitrate, sulphate, ammonium) data of non-refractory submicron (NR-PM1) aerosol from the first long-term deployment (27 July 2012 to 02 October 2013) of a time-of-flight aerosol chemical speciation monitor (ToF-ACSM) at the Swiss high altitude site Jungfraujoch (3580 m a.s.l.) are presented. Besides total mass loadings, diurnal variations and relative species contributions during the different meteorological seasons, geographical origin and sources of organic aerosol (OA) are discussed. Backward transport simulations shows that the highest (especially sulphate) concentrations of NR-PM1 were measured in air masses advected to the station from regions south of the JFJ while lowest concentrations were seen from western regions. OA source apportionment for each season was performed using the Source Finder (SoFi) interface for the multilinear engine (ME-2). OA was dominated in all seasons by oxygenated OA (OOA, 71-88 %), with lesser contributions from local tourism-related activities (7-12 %) and hydrocarbon-like OA related to regional vertical transport (3-9 %). In summer the OOA can be separated into a background low-volatility OA (LV-OOA I, possibly associated with long range transport) and a slightly less oxidised low-volatility OA (LV-OOA II) associated with regional vertical transport. Wood burning-related OA associated with regional transport was detected during the whole winter 2012/2013 and during rare events in summer 2013, in the latter case attributed to small scale transport for the surrounding valleys. Additionally, the data were divided into periods with free tropospheric (FT) conditions and periods with planetary boundary layer (PBL) influence enabling the assessment of the composition for each. Most nitrate and part of the OA is injected from the regional PBL while sulphate is mainly produced in the FT. The south/north gradient of sulphate is also pronounced in FT air masses (sulphate mass fraction from the south: 45 %, from

  12. Fourteen months of on-line measurements of the non-refractory submicron aerosol at the Jungfraujoch (3580 m a.s.l.) - chemical composition, origins and organic aerosol sources

    NASA Astrophysics Data System (ADS)

    Fröhlich, R.; Cubison, M. J.; Slowik, J. G.; Bukowiecki, N.; Canonaco, F.; Croteau, P. L.; Gysel, M.; Henne, S.; Herrmann, E.; Jayne, J. T.; Steinbacher, M.; Worsnop, D. R.; Baltensperger, U.; Prévôt, A. S. H.

    2015-10-01

    Chemically resolved (organic, nitrate, sulfate, ammonium) data of non-refractory submicron (NR-PM1) aerosol from the first long-term deployment (27 July 2012 to 02 October 2013) of a time-of-flight aerosol chemical speciation monitor (ToF-ACSM) at the Swiss high-altitude site Jungfraujoch (JFJ; 3580 m a.s.l.) are presented. Besides total mass loadings, diurnal variations and relative species contributions during the different meteorological seasons, geographical origin and sources of organic aerosol (OA) are discussed. Backward transport simulations show that the highest (especially sulfate) concentrations of NR-PM1 were measured in air masses advected to the station from regions south of the JFJ, while lowest concentrations were seen from western regions. OA source apportionment for each season was performed using the Source Finder (SoFi) interface for the multilinear engine (ME-2). OA was dominated in all seasons by oxygenated OA (OOA, 71-88 %), with lesser contributions from local tourism-related activities (7-12 %) and hydrocarbon-like OA related to regional vertical transport (3-9 %). In summer the OOA can be separated into a background low-volatility OA (LV-OOA I, possibly associated with long-range transport) and a slightly less oxidised low-volatility OA (LV-OOA II) associated with regional vertical transport. Wood burning-related OA associated with regional transport was detected during the whole winter 2012/2013 and during rare events in summer 2013, in the latter case attributed to small-scale transport for the surrounding valleys. Additionally, the data were divided into periods with free tropospheric (FT) conditions and periods with planetary boundary layer (PBL) influence, enabling the assessment of the composition for each. Most nitrate and part of the OA are injected from the regional PBL, while sulfate is mainly produced in the FT. The south/north gradient of sulfate is also pronounced in FT air masses (sulfate mass fraction from the south: 45

  13. 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

  14. Asian aerosols in North America: Extracting the chemical composition and mass concentration of the Asian continental aerosol plume from long-term aerosol records in the western United States

    NASA Astrophysics Data System (ADS)

    Vancuren, Richard A.

    2003-10-01

    Empirical assessment of the frequency and intensity of dust transport from Asia to North America has found that the dust regularly impacts elevated sites in the western United States, revealing a pattern of consistent, frequent transport above the marine boundary layer. Using the dust as a marker for Asian transport, a subset of Asian-influenced samples was identified within a decade of routine aerosol samples from two sites in the western cordillera of North America: Crater Lake, Oregon, and Mount Lassen, California. This subset was used to guide a statistical analysis to isolate Asian aerosol against the "background" of local contaminants. The analysis was then generalized to all samples during the transport season (March-October) for 1989-1999. A mixture of dust and combustion products dominates the Asian aerosol with typical concentration around 5 μg/m3 and mass median diameter between 2 and 3 μm. Major fine particle (<2.5 μm diameter) constituent fractions are ˜30% mineral, 28% organic compounds, 4% elemental carbon, 10% sulfate, <5% nitrate, and <1% sea salt. A second, possibly Asian, component of aged biomass smoke and sea salt is also present, with typical concentration (when present) around 1.5 μg/m3. Averaged over the transport season the dusty Asian aerosol and the smoky aerosol comprise 60 and 6%, respectively, of total particle mass (<10 μm diameter) and 72 and 13% of fine particle mass at these sites. These data indicate that the Asian continental plume is a significant contributor to aerosol loading at remote high-altitude sites across western North America. This implies a significant influence for Asian emissions on free troposphere aerosols over North America and suggests that they need to be explicitly accounted for in aerosol analyses ranging from climate studies to aerosol regulatory programs.

  15. Spatial and Temporal Variation in Fine Particulate Matter Mass and Chemical Composition: The Middle East Consortium for Aerosol Research Study

    PubMed Central

    Abdeen, Ziad; Heo, Jongbae; Wu, Bo; Shpund, Jacob; Vanger, Arye; Sharf, Geula; Moise, Tamar; Brenner, Shmuel; Nassar, Khaled; Saleh, Rami; Al-Mahasneh, Qusai M.; Sarnat, Jeremy A.; Schauer, James J.

    2014-01-01

    Ambient fine particulate matter (PM2.5) samples were collected from January to December 2007 to investigate the sources and chemical speciation in Palestine, Jordan, and Israel. The 24-h PM2.5 samples were collected on 6-day intervals at eleven urban and rural sites simultaneously. Major chemical components including metals, ions, and organic and elemental carbon were analyzed. The mass concentrations of PM2.5 across the 11 sites varied from 20.6 to 40.3 μg/m3, with an average of 28.7 μg/m3. Seasonal variation of PM2.5 concentrations was substantial, with higher average concentrations (37.3 μg/m3) in the summer (April–June) months compared to winter (October–December) months (26.0 μg/m3) due mainly to high contributions of sulfate and crustal components. PM2.5 concentrations in the spring were greatly impacted by regional dust storms. Carbonaceous mass was the most abundant component, contributing 40% to the total PM2.5 mass averaged across the eleven sites. Crustal components averaged 19.1% of the PM2.5 mass and sulfate, ammonium, and nitrate accounted for 16.2%, 6.4%, and 3.7%, respectively, of the total PM2.5 mass. The results of this study demonstrate the need to better protect the health and welfare of the residents on both sides of the Jordan River in the Middle East. PMID:25045751

  16. Spatial and temporal variation in fine particulate matter mass and chemical composition: the Middle East Consortium for Aerosol Research Study.

    PubMed

    Abdeen, Ziad; Qasrawi, Radwan; Heo, Jongbae; Wu, Bo; Shpund, Jacob; Vanger, Arye; Sharf, Geula; Moise, Tamar; Brenner, Shmuel; Nassar, Khaled; Saleh, Rami; Al-Mahasneh, Qusai M; Sarnat, Jeremy A; Schauer, James J

    2014-01-01

    Ambient fine particulate matter (PM2.5) samples were collected from January to December 2007 to investigate the sources and chemical speciation in Palestine, Jordan, and Israel. The 24-h PM2.5 samples were collected on 6-day intervals at eleven urban and rural sites simultaneously. Major chemical components including metals, ions, and organic and elemental carbon were analyzed. The mass concentrations of PM2.5 across the 11 sites varied from 20.6 to 40.3 μg/m(3), with an average of 28.7 μg/m(3). Seasonal variation of PM2.5 concentrations was substantial, with higher average concentrations (37.3 μg/m(3)) in the summer (April-June) months compared to winter (October-December) months (26.0 μg/m(3)) due mainly to high contributions of sulfate and crustal components. PM2.5 concentrations in the spring were greatly impacted by regional dust storms. Carbonaceous mass was the most abundant component, contributing 40% to the total PM2.5 mass averaged across the eleven sites. Crustal components averaged 19.1% of the PM2.5 mass and sulfate, ammonium, and nitrate accounted for 16.2%, 6.4%, and 3.7%, respectively, of the total PM2.5 mass. The results of this study demonstrate the need to better protect the health and welfare of the residents on both sides of the Jordan River in the Middle East.

  17. 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.

  18. Sensitivity of Tropospheric Chemical Composition to Halogen-Radical Chemistry Using a Fully Coupled Size-Resolved Multiphase Chemistry-Global Climate System: Halogen Distributions, Aerosol Composition, and Sensitivity of Climate-Relevant Gases

    SciTech Connect

    Long, M.; Keene, W. C.; Easter, Richard C.; Sander, Rolf; Liu, Xiaohong; Kerkweg, A.; Erickson, D.

    2014-04-07

    Observations and model studies suggest a significant but highly non-linear role for halogens, primarily Cl and Br, in multiphase atmospheric processes relevant to tropospheric chemistry and composition, aerosol evolution, radiative transfer, weather, and climate. The sensitivity of global atmospheric chemistry to the production of marine aerosol and the associated activation and cycling of inorganic Cl and Br was tested using a size-resolved multiphase coupled chemistry/global climate model (National Center for Atmospheric Research’s Community Atmosphere Model (CAM); v3.6.33). Simulation results showed strong meridional and vertical gradients in Cl and Br species. The simulation reproduced most available observations with reasonable confidence permitting the formulation of potential mechanisms for several previously unexplained halogen phenomena including the enrichment of Br- in submicron aerosol, and the presence of a BrO maximum in the polar free troposphere. However, simulated total volatile Br mixing ratios were generally high in the troposphere. Br in the stratosphere was lower than observed due to the lack of long-lived organobromine species in the simulation. Comparing simulations using chemical mechanisms with and without reactive Cl and Br species demonstrated a significant temporal and spatial sensitivity of primary atmospheric oxidants (O3, HOx, NOx), CH4, and non-methane hydrocarbons (NMHC’s) to halogen cycling. Simulated O3 and NOx were globally lower (65% and 35%, respectively, less in the planetary boundary layer based on median values) in simulations that included halogens. Globally, little impact was seen in SO2 and non-sea-salt SO42- processing due to halogens. Significant regional differences were evident: The lifetime of nss-SO42- was extended downwind of large sources of SO2. The burden and lifetime of DMS (and its oxidation products) were lower by a factor of 5 in simulations that included halogens, versus those without, leading to a 20

  19. Aerosol simulation including chemical and nuclear reactions

    SciTech Connect

    Marwil, E.S.; Lemmon, E.C.

    1985-01-01

    The numerical simulation of aerosol transport, including the effects of chemical and nuclear reactions presents a challenging dynamic accounting problem. Particles of different sizes agglomerate and settle out due to various mechanisms, such as diffusion, diffusiophoresis, thermophoresis, gravitational settling, turbulent acceleration, and centrifugal acceleration. Particles also change size, due to the condensation and evaporation of materials on the particle. Heterogeneous chemical reactions occur at the interface between a particle and the suspending medium, or a surface and the gas in the aerosol. Homogeneous chemical reactions occur within the aersol suspending medium, within a particle, and on a surface. These reactions may include a phase change. Nuclear reactions occur in all locations. These spontaneous transmutations from one element form to another occur at greatly varying rates and may result in phase or chemical changes which complicate the accounting process. This paper presents an approach for inclusion of these effects on the transport of aerosols. The accounting system is very complex and results in a large set of stiff ordinary differential equations (ODEs). The techniques for numerical solution of these ODEs require special attention to achieve their solution in an efficient and affordable manner. 4 refs.

  20. 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.

  1. Computing Equilibrium Chemical Compositions

    NASA Technical Reports Server (NTRS)

    Mcbride, Bonnie J.; Gordon, Sanford

    1995-01-01

    Chemical Equilibrium With Transport Properties, 1993 (CET93) computer program provides data on chemical-equilibrium compositions. Aids calculation of thermodynamic properties of chemical systems. Information essential in design and analysis of such equipment as compressors, turbines, nozzles, engines, shock tubes, heat exchangers, and chemical-processing equipment. CET93/PC is version of CET93 specifically designed to run within 640K memory limit of MS-DOS operating system. CET93/PC written in FORTRAN.

  2. Microphysical, chemical and optical aerosol properties in the Baltic Sea region

    NASA Astrophysics Data System (ADS)

    Kikas, Ülle; Reinart, Aivo; Pugatshova, Anna; Tamm, Eduard; Ulevicius, Vidmantas

    2008-11-01

    The microphysical structure, chemical composition and prehistory of aerosol are related to the aerosol optical properties and radiative effect in the UV spectral range. The aim of this work is the statistical mapping of typical aerosol scenarios and adjustment of regional aerosol parameters. The investigation is based on the in situ measurements in Preila (55.55° N, 21.00° E), Lithuania, and the AERONET data from the Gustav Dalen Tower (58 N, 17 E), Sweden. Clustering of multiple characteristics enabled to distinguish three aerosol types for clear-sky periods: 1) clean maritime-continental aerosol; 2) moderately polluted maritime-continental aerosol; 3) polluted continental aerosol. Differences between these types are due to significant differences in aerosol number and volume concentration, effective radius of volume distribution, content of SO 4- ions and Black Carbon, as well as different vertical profiles of atmospheric relative humidity. The UV extinction, aerosol optical depth (AOD) and the Ångstrom coefficient α increased with the increasing pollution. The value α = 1.96 was observed in the polluted continental aerosol that has passed over central and eastern Europe and southern Russia. Reduction of the clear-sky UV index against the aerosol-free atmosphere was of 4.5%, 27% and 41% for the aerosol types 1, 2 and 3, respectively.

  3. 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.

  4. 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

    The chemical composition and mixing states 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 measurements. They can accurately acquire aerosol components, however, the sampling or air exhausting could change the status of ambient aerosol or lead to 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 is able to detect aerosol information of entire atmosphere by optical and microphysical properties without destructing the natural status of ambient aerosol. This paper introduces 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. Different mixing models such as Maxwell-Garnett (MG), Bruggeman (BR) and Volume Average (VA) are also studied. 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 measurements obtained from Beijing site under different weather conditions, including polluted haze, dust storm and clean days, to investigate the impacts of mixing

  5. 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.

  6. Chemical aerosol detection using femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Alexander, Dennis R.; Rohlfs, Mark L.; Stauffer, John C.

    1997-07-01

    Many chemical warfare agents are dispersed as small aerosol particles. In the past, most electro-optical excitation and detection schemes have used continuous or pulsed lasers with pulse lengths ranging from nanoseconds to microseconds. In this paper, we present interesting ongoing new results on femtosecond imaging and on the time dependent solutions to the scattering problem of a femtosecond laser pulse interacting with a single small aerosol particle. Results are presented for various incident pulse lengths. Experimental imaging results using femtosecond pulses indicate that the diffraction rings present when using nanosecond laser pulses for imaging are greatly reduced when femtosecond laser pulses are used. Results are presented in terms of the internal fields as a function of time and the optical size parameter.

  7. Chemical, physical, and optical evolution of biomass burning aerosols: a case study

    NASA Astrophysics Data System (ADS)

    Adler, G.; Flores, J. M.; Abo Riziq, A.; Borrmann, S.; Rudich, Y.

    2011-02-01

    In-situ chemical composition measurements of ambient aerosols have been used for characterizing the evolution of submicron aerosols from a large anthropogenic biomass burning (BB) event in Israel. A high resolution Time of Flight Aerosol Mass Spectrometer (HR-RES-TOF-AMS) was used to follow the chemical evolution of BB aerosols during a night-long, extensive nationwide wood burning event and during the following day. While these types of extensive BB events are not common in this region, burning of agricultural waste is a common practice. The aging process of the BB aerosols was followed through their chemical, physical and optical properties. Mass spectrometric analysis of the aerosol organic component showed that aerosol aging is characterized by shifting from less oxidized fresh BB aerosols to more oxidized aerosols. Evidence for aerosol aging during the day following the BB event was indicated by an increase in the organic mass, its oxidation state, the total aerosol concentration, and a shift in the modal particle diameter. The effective broadband refractive index (EBRI) was derived using a white light optical particle counter (WELAS). The average EBRI for a mixed population of aerosols dominated by open fires was m = 1.53(±0.03) + 0.07i(±0.03), during the smoldering phase of the fires we found the EBRI to be m = 1.54(±0.01) + 0.04i(±0.01) compared to m = 1.49(±0.01) + 0.02i(±0.01) of the aged aerosols during the following day. This change indicates a decrease in the overall aerosol absorption and scattering. Elevated levels of particulate Polycyclic Aromatic Hydrocarbons (PAHs) were detected during the entire event, which suggest possible implications for human health during such extensive event.

  8. 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.

  9. 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

    The influences of atmospheric aerosols on cloud properties (i.e., aerosol indirect effects) strongly depend on the aerosol CCN concentrations, which can be effectively predicted from detailed aerosol size distribution, mixing state, and chemical composition using Köhler theory. However, atmospheric aerosols are complex and heterogeneous mixtures of a large number of species that cannot be individually simulated in global or regional models due to computational constraints. Furthermore, the thermodynamic properties or even the molecular identities of many organic species present in ambient aerosols are often not known to predict their cloud-activation behavior using Köhler theory. As a result, simplified presentations of aerosol composition and mixing state are necessary for large-scale models. In this study, aerosol microphysics, CCN concentrations, and chemical composition measured at the T0 urban super-site in Mexico City during MILAGRO are analyzed. During the campaign in March 2006, aerosol size distribution and composition often showed strong diurnal variation as a result of both primary emissions and aging of aerosols through coagulation and local photochemical production of secondary aerosol species. The submicron aerosol composition was ~1/2 organic species. Closure analysis is first carried out by comparing CCN concentrations calculated from the measured aerosol size distribution, mixing state, and chemical composition using extended Köhler theory to concurrent CCN measurements at five supersaturations ranging from 0.11% to 0.35%. The closure agreement and its diurnal variation are studied. CCN concentrations are also derived using various simplifications of the measured aerosol mixing state and chemical composition. The biases associated with these simplifications are compared for different supersaturations, and the variation of the biases is examined as a function of aerosol age. The results show that the simplification of internally mixed, size

  10. Use of high-volume outdoor smog chamber photo-reactors for studying physical and chemical atmospheric aerosol formation and composition

    NASA Astrophysics Data System (ADS)

    Borrás, E.; Ródenas, M.; Vera, T.; Muñoz, A.

    2015-12-01

    The atmospheric particulate matter has a large impact on climate, biosphere behaviour and human health. Its study is complex because of large number of species are present at low concentrations and the continuous time evolution, being not easily separable from meteorology, and transport processes. Closed systems have been proposed by isolating specific reactions, pollutants or products and controlling the oxidizing environment. High volume simulation chambers, such as EUropean PHOtoREactor (EUPHORE), are an essential tool used to simulate atmospheric photochemical reactions. This communication describes the last results about the reactivity of prominent atmospheric pollutants and the subsequent particulate matter formation. Specific experiments focused on organic aerosols have been developed at the EUPHORE photo-reactor. The use of on-line instrumentation, supported by off-line techniques, has provided well-defined reaction profiles, physical properties, and up to 300 different species are determined in particulate matter. The application fields include the degradation of anthropogenic and biogenic pollutants, and pesticides under several atmospheric conditions, studying their contribution on the formation of secondary organic aerosols (SOA). The studies performed at the EUPHORE have improved the mechanistic studies of atmospheric degradation processes and the knowledge about the chemical and physical properties of atmospheric particulate matter formed during these processes.

  11. 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.

  12. Multi- year Arctic and Antarctic aerosol chemical characterization

    NASA Astrophysics Data System (ADS)

    Udisti, Roberto; Becagli, Silvia; Caiazzo, Laura; Calzolai, Giulia; Cappelletti, David; Giardi, Fabio; Grotti, Marco; Malandrino, Mery; Nava, Silvia; Severi, Mirko; Traversi, Rita

    2016-04-01

    Long term measurements of aerosol chemical composition in polar region are particularly relevant to investigate potential climatic effects of atmospheric components arising from both natural and anthropogenic emissions. In order to improve our knowledge on the atmospheric load and chemical composition of polar aerosol, several measurements and sampling campaigns were carried out both in Antarctica and in the Arctic since 2005.The main results are here reported. As regard as Antarctica, a continuous all-year-round sampling of size-segregated aerosol was carried from 2005 to 2013 at Dome C (East Antarctica; 75° 60' S, 123° 200' E, 3220 m a.s.l. and 1100 km away from the nearest coast). Aerosol was collected by PM10 and PM2.5 samplers and by multi-stage impactors (Dekati 4-stage impactor). Chemical analysis was carried out by Ion Chromatography (ions composition) and ICP-MS (trace metals). Sea spray showed a sharp seasonal pattern, with winter (Apr-Nov) concentrations about ten times larger than summer (Dec-Mar). Besides, in winter, sea spray particles are mainly sub micrometric, while the summer size-mode is around 1-2 um. Meteorological analysis and air mass back trajectory reconstructions allowed the identification of two major air mass pathways: micrometric fractions for transport from the closer Indian-Pacific sector, and sub-micrometric particles for longer trajectories over the Antarctic Plateau. The markers of oceanic biogenic emission (methanesulfonic acid - MSA, and non-sea-salt sulphate) exhibit a seasonal cycle with summer maxima (Nov-Mar). Their size distributions show two modes (0.4- 0.7 um and 1.1-2.1 um) in early summer and just one sub-micrometric mode in full summer. The two modes are related to different transport pathways. In early summer, air masses came primarily from the Indian Ocean and spent a long time over the continent. The transport of sulphur compounds is related to sea spray aerosols and the resulting condensation of H2SO4 and MSA over

  13. Ship diesel emission aerosols: A comprehensive study on the chemical composition, the physical properties and the molecular biological and toxicological effects on human lung cells of aerosols from a ship diesel engine operated with heavy or light diesel fuel oil

    NASA Astrophysics Data System (ADS)

    Zimmermann, R.; Buters, J.; Öder, S.; Dietmar, G.; Kanashova, T.; Paur, H.; Dilger, M.; Mülhopt, S.; Harndorf, H.; Stengel, B.; Rabe, R.; Hirvonen, M.; Jokiniemi, J.; Hiller, K.; Sapcariu, S.; Berube, K.; Sippula, O.; Streibel, T.; Karg, E.; Schnelle-Kreis, J.; Lintelmann, J.; Sklorz, M.; Arteaga Salas, M.; Orasche, J.; Müller, L.; Reda, A.; Passig, J.; Radischat, C.; Gröger, T.; Weiss, C.

    2013-12-01

    The Virtual Helmholtz Institute-HICE (www.hice-vi.eu) addresses chemical & physical properties, transformation processes and health effects of anthropogenic combustion emissions. This is performed by thorough comprehensive chemical and physical characterization of combustion aerosols (including application of advantageous on-line methods) and studying of biological effects on human lung cell-cultures. A new ALI air-liquid-interface (ALI) exposition system and a mobile S2-biological laboratory were developed for the HICE-measurements. Human alveolar basal epithelial cells (A549 etc.) are ALI-exposed to fresh, diluted (1:40-1:100) combustion aerosols and subsequently were toxicologically and molecular-biologically characterized (e.g. proteomics). By using stable isotope labeling technologies (13C-Glucose/metabolomics; 2H-Lysine/SILAC-proteomics), high sensitivity and accuracy for detection of molecular-biological effects is achievable even at sub-toxic effect dose levels. Aerosols from wood combustion and ship diesel engine (heavy/light fuel oil) have been investigated. The effect of wood combustion and ship diesel PM e.g. on the protein expression of ALI-exposed A549 cells was compared. Filtered aerosol is used as gas-reference for the isotope labeling based method (SILAC). Therefore the effects of wood combustion- and shipping diesel-PM can be directly compared. Ship diesel aerosol causes a broader distribution in the observed fold changes (log2), i.e. more proteins are significantly up-/down-regulated in case of shipping diesel PM-exposure. This corresponds to a stronger biological reaction if compared to wood combustion-PM exposure. The chemical analysis results on wood combustion- and ship diesel-PM depict more polycyclic aromatic hydrocarbons (PAH)/oxidized-PAH but less of some transition metals (V, Fe) in the wood combustion case. Interestingly, alkylated PAH are considerably more abundant in shipping PM, suggesting that PAH/Oxy-PAH may be less relevant for

  14. Intermediate Volatility Organic Compound Emissions from On-Road Diesel Vehicles: Chemical Composition, Emission Factors, and Estimated Secondary Organic Aerosol Production.

    PubMed

    Zhao, Yunliang; Nguyen, Ngoc T; Presto, Albert A; Hennigan, Christopher J; May, Andrew A; Robinson, Allen L

    2015-10-06

    Emissions of intermediate-volatility organic compounds (IVOCs) from five on-road diesel vehicles and one off-road diesel engine were characterized during dynamometer testing. The testing evaluated the effects of driving cycles, fuel composition and exhaust aftertreatment devices. On average, more than 90% of the IVOC emissions were not identified on a molecular basis, instead appearing as an unresolved complex mixture (UCM) during gas-chromatography mass-spectrometry analysis. Fuel-based emissions factors (EFs) of total IVOCs (speciated + unspeciated) depend strongly on aftertreatment technology and driving cycle. Total-IVOC emissions from vehicles equipped with catalyzed diesel particulate filters (DPF) are substantially lower (factor of 7 to 28, depending on driving cycle) than from vehicles without any exhaust aftertreatment. Total-IVOC emissions from creep and idle operations are substantially higher than emissions from high-speed operations. Although the magnitude of the total-IVOC emissions can vary widely, there is little variation in the IVOC composition across the set of tests. The new emissions data are combined with published yield data to investigate secondary organic aerosol (SOA) formation. SOA production from unspeciated IVOCs is estimated using surrogate compounds, which are assigned based on gas-chromatograph retention time and mass spectral signature of the IVOC UCM. IVOCs contribute the vast majority of the SOA formed from exhaust from on-road diesel vehicles. The estimated SOA production is greater than predictions by previous studies and substantially higher than primary organic aerosol. Catalyzed DPFs substantially reduce SOA formation potential of diesel exhaust, except at low speed operations.

  15. 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

  16. Modeling comprehensive chemical composition of weathered oil following a marine spill to predict ozone and potential secondary aerosol formation and constrain transport pathways

    NASA Astrophysics Data System (ADS)

    Drozd, Greg T.; Worton, David R.; Aeppli, Christoph; Reddy, Christopher M.; Zhang, Haofei; Variano, Evan; Goldstein, Allen H.

    2015-11-01

    Releases of hydrocarbons from oil spills have large environmental impacts in both the ocean and atmosphere. Oil evaporation is not simply a mechanism of mass loss from the ocean, as it also causes production of atmospheric pollutants. Monitoring atmospheric emissions from oil spills must include a broad range of volatile organic compounds (VOC), including intermediate-volatile and semivolatile compounds (IVOC, SVOC), which cause secondary organic aerosol (SOA) and ozone production. The Deepwater Horizon (DWH) disaster in the northern Gulf of Mexico during Spring/Summer of 2010 presented a unique opportunity to observe SOA production due to an oil spill. To better understand these observations, we conducted measurements and modeled oil evaporation utilizing unprecedented comprehensive composition measurements, achieved by gas chromatography with vacuum ultraviolet time of flight mass spectrometry (GC-VUV-HR-ToFMS). All hydrocarbons with 10-30 carbons were classified by degree of branching, number of cyclic rings, aromaticity, and molecular weight; these hydrocarbons comprise ˜70% of total oil mass. Such detailed and comprehensive characterization of DWH oil allowed bottom-up estimates of oil evaporation kinetics. We developed an evaporative model, using solely our composition measurements and thermodynamic data, that is in excellent agreement with published mass evaporation rates and our wind-tunnel measurements. Using this model, we determine surface slick samples are composed of oil with a distribution of evaporative ages and identify and characterize probable subsurface transport of oil.

  17. Measurements of Sea Salt Aerosols in the Marine Boundary Layer and Free Troposphere: Vertical Transport and Chemical Transformation

    NASA Astrophysics Data System (ADS)

    Hudson, P. K.; Murphy, D. M.; Cziczo, D. J.; Thomson, D. S.

    2002-12-01

    During the Intercontinental Transport and Chemical Transformation (ITCT) mission (Monterey, CA, spring 2002) nearly 400,000 positive and negative mass spectra of single atmospheric aerosols were acquired using the PALMS (Particle Analysis by Laser Mass Spectrometry) instrument. The primary focus of the mission was to investigate the composition of air masses along the western coast of the United States. Of particular interest to the mission was to study the influence of anthropogenic emissions from Asia on aerosol composition. To accomplish these goals, the WP-3 aircraft, equipped with a suite of instruments including PALMS, covered a large spatial area flying from 0 - 8000 m altitude covering most of the western coastline from Canada to southern California including flights over the San Francisco and Los Angeles metropolitan areas. The in situ measurements of single particle aerosol mass spectra by PALMS allow for good spatial and vertical resolution of the aerosol composition. By observing the changes in aerosol composition as a function of altitude, the vertical transport of sea salt aerosols over marine and urban environments is examined. Using measurements of other chemical tracers along with the aerosol composition, the chemical processing of these aerosols during transport both vertically and inland can be discerned. These results add insight into the transport and chemical evolution of sea salt aerosol.

  18. New insights into PM2.5 chemical composition and sources in two major cities in China during extreme haze events using aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    Elser, Miriam; Huang, Ru-Jin; Wolf, Robert; Slowik, Jay G.; Wang, Qiyuan; Canonaco, Francesco; Li, Guohui; Bozzetti, Carlo; Daellenbach, Kaspar R.; Huang, Yu; Zhang, Renjian; Li, Zhengqiang; Cao, Junji; Baltensperger, Urs; El-Haddad, Imad; Prévôt, André S. H.

    2016-03-01

    During winter 2013-2014 aerosol mass spectrometer (AMS) measurements were conducted for the first time with a novel PM2.5 (particulate matter with aerodynamic diameter ≤ 2.5 µm) lens in two major cities of China: Xi'an and Beijing. We denote the periods with visibility below 2 km as extreme haze and refer to the rest as reference periods. During the measurements in Xi'an an extreme haze covered the city for about a week and the total non-refractory (NR)-PM2.5 mass fraction reached peak concentrations of over 1000 µg m-3. During the measurements in Beijing two extreme haze events occurred, but the temporal extent and the total concentrations reached during these events were lower than in Xi'an. Average PM2.5 concentrations of 537 ± 146 and 243 ± 47 µg m-3 (including NR species and equivalent black carbon, eBC) were recorded during the extreme haze events in Xi'an and Beijing, respectively. During the reference periods the measured average concentrations were 140 ± 99 µg m-3 in Xi'an and 75 ± 61 µg m-3 in Beijing. The relative composition of the NR-PM2.5 evolved substantially during the extreme haze periods, with increased contributions of the inorganic components (mostly sulfate and nitrate). Our results suggest that the high relative humidity present during the extreme haze events had a strong effect on the increase of sulfate mass (via aqueous phase oxidation of sulfur dioxide). Another relevant characteristic of the extreme haze is the size of the measured particles. During the extreme haze events, the AMS showed much larger particles, with a volume weighted mode at about 800 to 1000 nm, in contrast to about 400 nm during reference periods. These large particle sizes made the use of the PM2.5 inlet crucial, especially during the severe haze events, where 39 ± 5 % of the mass would have been lost in the conventional PM1 (particulate matter with aerodynamic diameter ≤ 1 µm) inlet. A novel positive matrix factorization procedure was developed to

  19. New insights into PM2.5 chemical composition and sources in two major cities in China during extreme haze events using aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    Elser, M.; Huang, R.-J.; Wolf, R.; Slowik, J. G.; Wang, Q.-Y.; Canonaco, F.; Li, G. H.; Bozzetti, C.; Daellenbach, K. R.; Huang, Y.; Zhang, R.-J.; Li, Z.-Q.; Cao, J. J.; Baltensperger, U.; El-Haddad, I.; Prévôt, A. S. H.

    2015-11-01

    During winter 2013-2014 aerosol mass spectrometer (AMS) measurements were conducted for the first time with a novel PM2.5 (particulate matter with aerodynamic diameter ≤ 2.5 μm) lens in two major cities of China: Xi'an and Beijing. We denote the periods with visibility below 2 km as extreme haze and refer to the rest as reference periods. During the measurements in Xi'an an extreme haze covered the city for about a week and the total non-refractory (NR)-PM2.5 mass fraction reached peak concentrations of over 1000 μg m-3. During the measurements in Beijing two extreme haze events occurred, but the temporal extent and the total concentrations reached during these events were lower than in Xi'an. Average PM2.5 concentrations of 537 ± 146 μg m-3 and 243 ± 47 μg m-3 (including NR species and equivalent black carbon, eBC) were recorded during the extreme haze events in Xi'an and Beijing, respectively. During the reference periods the measured average concentrations were 140 ± 99 μg m-3 in Xi'an and 75 ± 61 μg m-3 in Beijing. The relative composition of the NR-PM2.5 evolved substantially during the extreme haze periods, with increased contributions of the inorganic components (mostly sulfate and nitrate). Our results suggest that the high relative humidity present during the extreme haze events had a strong effect on the increase of sulfate mass (via aqueous phase oxidation of sulfur dioxide). Another relevant characteristic of the extreme haze is the size of the measured particles. During the extreme haze events, the AMS showed much larger particles, with a volume weighted mode at about 800 to 1000 nm, in contrast to about 400 nm during reference periods. These large particle sizes made the use of the PM2.5 inlet crucial, especially during the severe haze events, where 39 ± 5 % of the mass would have been lost in the conventional PM1 (particulate matter with aerodynamic diameter ≤ 1 μm) inlet. A novel positive matrix factorization procedure was developed

  20. Chemical characterization and physico-chemical properties of aerosols at Villum Research Station, Greenland during spring 2015

    NASA Astrophysics Data System (ADS)

    Glasius, M.; Iversen, L. S.; Svendsen, S. B.; Hansen, A. M. K.; Nielsen, I. E.; Nøjgaard, J. K.; Zhang, H.; Goldstein, A. H.; Skov, H.; Massling, A.; Bilde, M.

    2015-12-01

    The effects of aerosols on the radiation balance and climate are of special concern in Arctic areas, which have experienced warming at twice the rate of the global average. As future scenarios include increased emissions of air pollution, including sulfate aerosols, from ship traffic and oil exploration in the Arctic, there is an urgent need to obtain the fundamental scientific knowledge to accurately assess the consequences of pollutants to environment and climate. In this work, we studied the chemistry of aerosols at the new Villum Research Station (81°36' N, 16°40' W) in north-east Greenland during the "inauguration campaign" in spring 2015. The chemical composition of sub-micrometer Arctic aerosols was investigated using a Soot Particle Time-of-Flight Aerosol Mass Spectrometer (SP-ToF-AMS). Aerosol samples were also collected on filters using both a high-volume sampler and a low-volume sampler equipped with a denuder for organic gases. Chemical analyses of filter samples include determination of inorganic anions and cations using ion-chromatography, and analysis of carboxylic acids and organosulfates of anthropogenic and biogenic origin using ultrahigh-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS). Previous studies found that organosulfates constitute a surprisingly high fraction of organic aerosols during the Arctic Haze period in winter and spring. Investigation of organic molecular tracers provides useful information on aerosol sources and atmospheric processes. The physico-chemical properties of Arctic aerosols are also under investigation. These measurements include particle number size distribution, water activity and surface tension of aerosol samples in order to deduct information on their hygroscopicity and cloud-forming potential. The results of this study are relevant to understanding aerosol sources and processes as well as climate effects in the Arctic, especially during the Arctic haze

  1. Modelling the chemically aged and mixed aerosols over the eastern central Atlantic Ocean - potential impacts

    NASA Astrophysics Data System (ADS)

    Astitha, M.; Kallos, G.; Spyrou, C.; O'Hirok, W.; Lelieveld, J.; Denier van der Gon, H. A. C.

    2010-07-01

    Detailed information on the chemical and physical properties of aerosols is important for assessing their role in air quality and climate. This work explores the origin and fate of continental aerosols transported over the Central Atlantic Ocean, in terms of chemical composition, number and size distribution, using chemistry-transport models, satellite data and in situ measurements. We focus on August 2005, a period with intense hurricane and tropical storm activity over the Atlantic Ocean. A mixture of anthropogenic (sulphates, nitrates), natural (desert dust, sea salt) and chemically aged (sulphate and nitrate on dust) aerosols is found entering the hurricane genesis region, most likely interacting with clouds in the area. Results from our modelling study suggest rather small amounts of accumulation mode desert dust, sea salt and chemically aged dust aerosols in this Atlantic Ocean region. Aerosols of smaller size (Aitken mode) are more abundant in the area and in some occasions sulphates of anthropogenic origin and desert dust are of the same magnitude in terms of number concentrations. Typical aerosol number concentrations are derived for the vertical layers near shallow cloud formation regimes, indicating that the aerosol number concentration can reach several thousand particles per cubic centimetre. The vertical distribution of the aerosols shows that the desert dust particles are often transported near the top of the marine cloud layer as they enter into the region where deep convection is initiated. The anthropogenic sulphate aerosol can be transported within a thick layer and enter the cloud deck through multiple ways (from the top, the base of the cloud, and by entrainment). The sodium (sea salt related) aerosol is mostly found below the cloud base. The results of this work may provide insights relevant for studies that consider aerosol influences on cloud processes and storm development in the Central Atlantic region.

  2. Chemically aged and mixed aerosols over the Central Atlantic Ocean - potential impacts

    NASA Astrophysics Data System (ADS)

    Astitha, M.; Kallos, G.; Spyrou, C.; O'Hirok, W.; Lelieveld, J.; Denier van der Gon, H. A. C.

    2010-02-01

    Detailed information on the chemical and physical properties of aerosols is important for assessing their role in air quality and climate. This work explores the origin and fate of continental aerosols transported over the Central Atlantic Ocean, in terms of chemical composition, number and size distribution, using chemistry-transport models, satellite data and in situ measurements. We focus on August 2005, a period with intense hurricane and tropical storm activity over the Atlantic Ocean. A mixture of anthropogenic (sulphates, nitrates), natural (desert dust, sea salt) and chemically aged (sulphate and nitrate on dust) aerosols is found entering the hurricane genesis region, most likely interacting with clouds in the area. Results from our modelling study suggest rather small amounts of accumulation mode desert dust, sea salt and chemically aged dust aerosols in this Atlantic Ocean region. Aerosols of smaller size (Aitken mode) are more abundant in the area and in some occasions sulphates of anthropogenic origin and desert dust are of the same magnitude in terms of number concentrations. Typical aerosol number concentrations are derived for the vertical layers near shallow cloud formation regimes, designating that the aerosol number concentration can reach several thousand particles per cubic centimetre. The vertical distribution of the aerosols indicates that the desert dust particles are often transported near the top of the marine cloud layer as they enter into the region where deep convection is initiated. The anthropogenic sulphate aerosol can be transported within a thick layer and enter the cloud deck through multiple ways (from the top, the base of the cloud and entrainment). The sodium (sea salt related) aerosol is mostly found below the cloud base. The results of this work may provide insights relevant for studies that consider aerosol influences on cloud processes and storm development in the Central Atlantic region.

  3. 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.

  4. Chemical composition of Mars

    NASA Technical Reports Server (NTRS)

    Morgan, J. W.; Anders, E.

    1979-01-01

    The chemical composition of Mars is estimated from the cosmochemical model of Ganapathy and Anders (1974) with additional petrological and geophysical constraints. The model assumes that planets and chondrites underwent the same fractionation processes in the solar nebula, and constraints are imposed by the abundance of the heat-producing elements, U, Th and K, the volatile-rich component and the high density of the mantle. Global abundances of 83 elements are presented, and it is noted that the mantle is an iron-rich garnet wehrlite, nearly identical to the bulk moon composition of Morgan at al. (1978) and that the core is sulfur poor (3.5% S). The comparison of model compositions for the earth, Venus, Mars, the moon and a eucrite parent body suggests that volatile depletion correlates mainly with size rather than with radial distance from the sun.

  5. Characterization of aerosol composition and sources in the greater Atlanta area by aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    Ng, N. L.; Xu, L.; Suresh, S.; Weber, R. J. J.; Baumann, K.; Edgerton, E. S.

    2014-12-01

    An important and uncertain aspect of biogenic secondary organic aerosol (SOA) formation is that it is often associated with anthropogenic pollution tracers. Prior studies in Atlanta suggested that 70-80% of the carbon in water-soluble organic carbon (WSOC) is modern, yet it is well-correlated with the anthropogenic CO. In this study, we deployed a High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and an Aerosol Chemical Speciation Monitor (ACSM) at multiple sites in different seasons (May 2012-February 2013) to characterize the sources and chemical composition of aerosols in the greater Atlanta area. This area in the SE US is ideal to investigate anthropogenic-biogenic interactions due to high natural and anthropogenic emissions. These extensive field studies are part of the Southeastern Center for Air Pollution and Epidemiology study (SCAPE). The HR-ToF-AMS is deployed at four sites (~ 3 weeks each) in rotation: Jefferson Street (urban), Yorkville (rural), roadside site (near Highway 75/85), and Georgia Tech site (campus), with the urban and rural sites being part of the SEARCH network. We obtained seven HR-ToF-AMS datasets in total. During the entire measurement period, the ACSM is stationary at the GIT site and samples continuously. We perform positive matrix factorization (PMF) analysis on the HR-ToF-AMS and ACSM data to deconvolve the OA into different components. While the diurnal cycle of the total OA is flat as what have been previously observed, the OA factors resolved by PMF analysis show distinctively different diurnal trends. We find that the "more-oxidized oxygenated OA" (MO-OOA) constitutes a major fraction of OA at all sites. In summer, OA is dominated by SOA, e.g., isoprene-OA and OOA with different degrees of oxidation. In contrary, biomass burning OA is more prominent in winter data. By comparing HR-ToF-AMS and ACSM data during the same sampling periods, we find that the aerosol time series are highly correlated, indicating the

  6. Chemical and Spatial Microscopy of Individual Organic Aerosols

    NASA Astrophysics Data System (ADS)

    Tivanski, Alexei V.; Hopkins, Rebecca J.; Gilles, Mary K.

    2008-03-01

    Carbonaceous particles originating from biomass burning can account for a large fraction of organic aerosols in a local environment. Presently, their composition, physical, and chemical properties as well as their environmental effects are largely unknown. A distinct type of biomass burn particles, called ``tar balls'', have been observed in a number of field campaigns, both in fresh and aged smoke. They are characterized by their spherical morphology, high carbon content and ability to efficiently scatter and absorb light. Here, a combination of scanning transmission x-ray microscopy and near edge x-ray absorption fine structure spectroscopy is used to determine the shape, structure and size-dependent chemical composition of 150 individual tar ball particles ranging in size from 0.15 to 1.2 μm. Oxygen is present primarily as carboxylic carbonyls and oxygen-substituted alkyl functional groups. The observed chemical composition is distinctly different from black carbon and more closely resembles high molecular weight humic-like substances. A detailed examination of the carbonyl intensity as a function of particle size reveals the presence of a thin oxygenated interface layer on the tar balls, indicative of atmospheric processing of biomass burn particles.

  7. Hygroscopic, Morphological, and Chemical Properties of Agricultural Aerosols

    NASA Astrophysics Data System (ADS)

    Hiranuma, N.; Brooks, S. D.; Cheek, L.; Thornton, D. C.; Auvermann, B. W.; Littleton, R.

    2007-12-01

    Agricultural fugitive dust is a significant source of localized air pollution in the semi-arid southern Great Plains. In the Texas Panhandle, daily episodes of ground-level fugitive dust emissions from the cattle feedlots are routinely observed in conjunction with increased cattle activity in the late afternoons and early evenings. We conducted a field study to characterize size-selected agricultural aerosols with respect to hygroscopic, morphological, and chemical properties and to attempt to identify any correlations between these properties. To explore the hygroscopic nature of agricultural particles, we have collected size-resolved aerosol samples using a cascade impactor system at a cattle feedlot in the Texas Panhandle and have used the Environmental Scanning Electron Microscope (ESEM) to determine the water uptake by individual particles in those samples as a function of relative humidity. To characterize the size distribution of agricultural aerosols as a function of time, A GRIMM aerosol spectrometer and Sequential Mobility Particle Sizer and Counter (SMPS) measurements were simultaneously performed in an overall size range of 11 nm to 20 µm diameters at a cattle feedlot. Complementary determination of the elemental composition of individual particles was performed using Energy Dispersive X-ray Spectroscopy (EDS). In addition to the EDS analysis, an ammonia scrubber was used to collect ammonia and ammonium in the gas and particulate phases, respectively. The concentration of these species was quantified offline via UV spectrophotometry at 640 nanometers. The results of this study will provide important particulate emission data from a feedyard, needed to improve our understanding of the role of agricultural particulates in local and regional air quality.

  8. 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

  9. Parameterization of Aerosol Sinks in Chemical Transport Models

    NASA Technical Reports Server (NTRS)

    Colarco, Peter

    2012-01-01

    The modelers point of view is that the aerosol problem is one of sources, evolution, and sinks. Relative to evolution and sink processes, enormous attention is given to the problem of aerosols sources, whether inventory based (e.g., fossil fuel emissions) or dynamic (e.g., dust, sea salt, biomass burning). On the other hand, aerosol losses in models are a major factor in controlling the aerosol distribution and lifetime. Here we shine some light on how aerosol sinks are treated in modern chemical transport models. We discuss the mechanisms of dry and wet loss processes and the parameterizations for those processes in a single model (GEOS-5). We survey the literature of other modeling studies. We additionally compare the budgets of aerosol losses in several of the ICAP models.

  10. 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.

  11. 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.

  12. Hygroscopic and chemical characterisation of Po Valley aerosol

    NASA Astrophysics Data System (ADS)

    Bialek, J.; Dall Osto, M.; Vaattovaara, P.; Decesari, S.; Ovadnevaite, J.; Laaksonen, A.; O'Dowd, C.

    2014-02-01

    Continental summer-time aerosol in the Italian Po Valley was characterised in terms of hygroscopic properties and the influence of chemical composition therein. Additionally, the ethanol affinity of particles was analysed. The campaign-average minima in hygroscopic growth factors (HGFs, at 90% relative humidity) occurred just before and during sunrise from 03:00 to 06:00 LT (all data are reported in the local time), but, more generally, the hygroscopicity during the whole night is very low, particularly in the smaller particle sizes. The average HGFs recorded during the low HGF period were in a range from 1.18 (for the smallest, 35nm particles) to 1.38 (for the largest, 165 nm particles). During the day, the HGF gradually increased to achieve maximum values in the early afternoon hours 12:00-15:00, reaching 1.32 for 35 nm particles and 1.46 for 165 nm particles. Two contrasting case scenarios were encountered during the measurement period: Case 1 was associated with westerly air flow moving at a moderate pace and Case 2 was associated with more stagnant, slower moving air from the north-easterly sector. Case 1 exhibited weak diurnal temporal patterns, with no distinct maximum or minimum in HGF or chemical composition, and was associated with moderate non-refractory aerosol mass concentrations (for 50% size cut at 1 μ) of the order of 4.5 μg m-3. For Case 1, organics contributed typically 50% of the mass. Case 2 was characterised by >9.5 μg m-3 total non-refractory mass (<1 μ) in the early morning hours (04:00), decreasing to ~3 μg m-3 by late morning (10:00) and exhibited strong diurnal changes in chemical composition, particularly in nitrate mass but also in total organic mass concentrations. Specifically, the concentrations of nitrate peaked at night-time, along with the concentrations of hydrocarbon-like organic aerosol (HOA) and of semi-volatile oxygenated organic aerosol (SV-OOA). In general, organic growth factors (OGFs) followed a trend which was

  13. Uncertainties of simulated aerosol optical properties induced by assumptions on aerosol physical and chemical properties: An AQMEII-2 perspective

    NASA Astrophysics Data System (ADS)

    Curci, G.; Hogrefe, C.; Bianconi, R.; Im, U.; Balzarini, A.; Baró, R.; Brunner, D.; Forkel, R.; Giordano, L.; Hirtl, M.; Honzak, L.; Jiménez-Guerrero, P.; Knote, C.; Langer, M.; Makar, P. A.; Pirovano, G.; Pérez, J. L.; San José, R.; Syrakov, D.; Tuccella, P.; Werhahn, J.; Wolke, R.; Žabkar, R.; Zhang, J.; Galmarini, S.

    2015-08-01

    The calculation of aerosol optical properties from aerosol mass is a process subject to uncertainty related to necessary assumptions on the treatment of the chemical species mixing state, density, refractive index, and hygroscopic growth. In the framework of the AQMEII-2 model intercomparison, we used the bulk mass profiles of aerosol chemical species sampled over the locations of AERONET stations across Europe and North America to calculate the aerosol optical properties under a range of common assumptions for all models. Several simulations with parameters perturbed within a range of observed values are carried out for July 2010 and compared in order to infer the assumptions that have the largest impact on the calculated aerosol optical properties. We calculate that the most important factor of uncertainty is the assumption about the mixing state, for which we estimate an uncertainty of 30-35% on the simulated aerosol optical depth (AOD) and single scattering albedo (SSA). The choice of the core composition in the core-shell representation is of minor importance for calculation of AOD, while it is critical for the SSA. The uncertainty introduced by the choice of mixing state choice on the calculation of the asymmetry parameter is the order of 10%. Other factors of uncertainty tested here have a maximum average impact of 10% each on calculated AOD, and an impact of a few percent on SSA and g. It is thus recommended to focus further research on a more accurate representation of the aerosol mixing state in models, in order to have a less uncertain simulation of the related optical properties.

  14. Chemical characterization of springtime submicrometer aerosol in Po Valley, Italy

    NASA Astrophysics Data System (ADS)

    Saarikoski, S.; Carbone, S.; Decesari, S.; Giulianelli, L.; Angelini, F.; Teinilä, K.; Canagaratna, M.; Ng, N. L.; Trimborn, A.; Facchini, M. C.; Fuzzi, S.; Hillamo, R.; Worsnop, D.

    2012-03-01

    The chemistry of submicron particles was investigated at San Pietro Capofiume (SPC) measurement station in the Po Valley, Italy, in spring 2008. The measurements were performed by using both off-line and on-line instruments. Organic carbon (OC) and elemental carbon, organic acids and biomass burning tracers were measured off-line by using a 24-h PM1 filter sampling. More detailed particle chemistry was achieved by using an Aerodyne high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and analyzing the data by positive matrix factorization (PMF). Oxalic acid had the highest concentrations of organic acids (campaign-average 97.4 ng m-3) followed by methane sulfonic, formic, malonic, and malic acids. Samples were also analyzed for glyoxylic, succinic, azelaic and maleic acids. In total, the nine acids composed 1.9 and 3.8% of OC and water-soluble OC, respectively (average), in terms of carbon atoms. Levoglucosan concentration varied from 17.7 to 495 ng m-3 with the concentration decreasing in the course of the campaign most likely due to the reduced use of domestic heating with wood. Six factors were found for organic aerosol (OA) at SPC by PMF: hydrocarbon-like OA (HOA), biomass burning OA (BBOA), nitrogen-containing OA (N-OA) and three different oxygenated OAs (OOA-a, OOA-b and OOA-c). Most of the OA mass was composed of OOA-a, HOA and OOA-c (26, 24 and 22%, respectively) followed by OOA-b (13%), BBOA (8%) and N-OA (7%). As expected, OOAs were the most oxygenated factors with organic matter:organic carbon (OM:OC) ratios ranging from 1.9 to 2.2. The diurnal variability of the aerosol chemical composition was greatly affected by the boundary layer meteorology. Specifically, the effect of the nocturnal layer break-up in morning hours was most evident for nitrate and N-OA indicating that these compounds originated mainly from the local sources in the Po Valley. For sulfate and OOA-a the concentration did not change during the break-up suggesting their

  15. Chemical characterization of springtime submicrometer aerosol in Po Valley, Italy

    NASA Astrophysics Data System (ADS)

    Saarikoski, S.; Carbone, S.; Decesari, S.; Giulianelli, L.; Angelini, F.; Canagaratna, M.; Ng, N. L.; Trimborn, A.; Facchini, M. C.; Fuzzi, S.; Hillamo, R.; Worsnop, D.

    2012-09-01

    The chemistry of submicron particles was investigated at San Pietro Capofiume (SPC) measurement station in the Po Valley, Italy, in spring 2008. The measurements were performed by using both off-line and on-line instruments. Organic carbon (OC) and elemental carbon, organic acids and biomass burning tracers were measured off-line by using a 24-h PM1 filter sampling. More detailed particle chemistry was achieved by using a Aerodyne high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and analyzing the data by positive matrix factorization (PMF). Oxalic acid had the highest concentrations of organic acids (campaign-average 97.4 ng m-3) followed by methane sulfonic, formic, malonic, and malic acids. Samples were also analyzed for glyoxylic, succinic, azelaic and maleic acids. In total, the nine acids composed 1.9 and 3.8% of OC and water-soluble OC, respectively (average), in terms of carbon atoms. Levoglucosan concentration varied from 17.7 to 495 ng m-3 with the concentration decreasing in the course of the campaign most likely due to the reduced use of domestic heating with wood. Six factors were found for organic aerosol (OA) at SPC by PMF: hydrocarbon-like OA (HOA), biomass burning OA (BBOA), nitrogen-containing OA (N-OA) and three different oxygenated OAs (OOA-a, OOA-b and OOA-c). Most of the OA mass was composed of OOA-a, HOA and OOA-c (26, 24 and 22%, respectively) followed by OOA-b (13%), BBOA (8%) and N-OA (7%). As expected, OOAs were the most oxygenated factors with organic matter:organic carbon (OM : OC) ratios ranging from 1.9 to 2.2. The diurnal variability of the aerosol chemical composition was greatly affected by the boundary layer meteorology. Specifically, the effect of the nocturnal layer break-up in morning hours was most evident for nitrate and N-OA indicating that these compounds originated mainly from the local sources in the Po Valley. For sulfate and OOA-a the concentration did not change during the break-up suggesting their

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Systematic Relationships among Background SE U.S. Aerosol Optical, Micro-physical, and Chemical Properties-Development of an Optically-based Aerosol Characterization

    NASA Astrophysics Data System (ADS)

    Sherman, J. P.; Link, M. F.; Zhou, Y.

    2014-12-01

    Remote sensing-based retrievals of aerosol composition require known or assumed relationships between aerosol optical properties and types. Most optically-based aerosol classification schemes apply some combination of the spectral dependence of aerosol light scattering and absorption-using the absorption and either scattering or extinction Angstrom exponents (AAE, SAE and EAE), along with single-scattering albedo (SSA). These schemes can differentiate between such aerosol types as dust, biomass burning, and urban/industrial but no such studies have been conducted in the SE U.S., where a large fraction of the background aerosol is a variable mixture of biogenic SOA, sulfates, and black carbon. In addition, AERONET retrievals of SSA are often highly uncertain due to low AOD in the region during most months. The high-elevation, semi-rural AppalAIR facility at Appalachian State University in Boone, NC (1090m ASL, 36.210N, 81.690W) is home to the only co-located NOAA-ESRL and AERONET monitoring sites in the eastern U.S. Aerosol chemistry measured at AppalAIR is representative of the background SE U.S (Link et al. 2014) Dried aerosol light absorption and dried and humidified aerosol light scattering and hemispheric backscattering at 3 visible wavelengths and 2 particle size cuts (sub-1μm and sub-10μm) are measured continuously. Measurements of size-resolved, non-refractory sub-1μm aerosol composition were made by a co-located AMS during the 2012-2013 summers and 2013 winter. Systematic relationships among aerosol optical, microphysical, and chemical properties were developed to better understand aerosol sources and processes and for use in higher-dimension aerosol classification schemes. The hygroscopic dependence of visible light scattering is sensitive to the ratio of sulfate to organic aerosol(OA), as are SSA and AAE. SAE is a less sensitive indicator of fine-mode aerosol size than hemispheric backscatter fraction (b) and is more sensitive to fine-mode aerosol

  1. Hygroscopic and chemical characterisation of Po Valley aerosol

    NASA Astrophysics Data System (ADS)

    Bialek, J.; Dall'Osto, M.; Vaattovaara, P.; Ovadnevaite, J.; Decesari, S.; Laaksonen, A.; O'Dowd, C.

    2013-02-01

    Continental summer-time aerosol in the Italian Po Valley was characterized in terms of hygroscopic properties and the influence of chemical composition therein. The campaign-average minima in hygroscopic growth factors (HGFs) occurred just before and during sunrise from 03:00-06:00, but more generally, the whole night shows very low hygroscopicity, particularly in the smaller particle sizes. The average HGFs increased from 1.18 for the smallest sized particles (35 nm) to 1.38 for the largest sizes (165 nm) for the lowest HGF period while during the day, the HGF gradually increased to achieve maximum values in the early afternoon hours from 12:00-15:00, reaching 1.32 for 35 nm particles and 1.46 for 165 nm particles. Two contrasting case scenarios were encountered during the measurement period: Case 1 was associated with westerly air flow moving at a moderate pace and Case 2 was associated with more stagnant, slower moving air from the north-easterly sector. Case 1 exhibited low diurnal temporal patterns and was associated with moderate non-refractory aerosol mass concentrations (for 50% size cut at 1 μm) of the order of 4.5 μg m-3. For Case 1, organics contributed typically to 50% of the mass. Case 2 was characterized by > 9.5 μg m-3 total mass (< 1 μm) in the early morning hours (04:00), decreasing to ∼ 3 μg m-3 by late morning (10:00) and exhibited strong diurnal changes in chemical composition, particularly in nitrate mass but also in total organic mass concentrations. Organic growth factors (OGFs) exhibited a minimum around 15:00, 1-2 h after the peak in HGF. Particles sized 165 nm exhibited moderate diurnal variability in HGF, ranging from 80% at night to 95% of "more hygroscopic" growth factors (i.e. GF = 1.35-1.9) around noon. The diurnal changes in HGF progressively became enhanced with decreasing particle size, decreasing from 95% "more hygroscopic" growth factor fraction at noon to 10% fraction at midnight, while the "less hygroscopic" growth

  2. Chemical composition and acidity of size-fractionated inorganic aerosols of 2013-14 winter haze in Shanghai and associated health risk of toxic elements

    NASA Astrophysics Data System (ADS)

    Behera, Sailesh N.; Cheng, Jinping; Huang, Xian; Zhu, Qiongyu; Liu, Ping; Balasubramanian, Rajasekhar

    2015-12-01

    The severe winter haze episode that occurred in Shanghai from December 2013 to January 2014, characterized by elevated levels of particulate matter (PM), received considerable international attention because of its impacts on public health and disruption of day-to-day activities. To examine the characteristics of PM during this haze episode and to assess the chemistry behind formation of secondary inorganic aerosols (SIA) and associated health impacts due to exposure of toxic elements, we characterized eight water soluble inorganic (WSI) ions and twenty four trace elements in twelve size-fractionated PM (10 nm-9.9 μm). The average mass concentrations of coarse (1.8 μm < Dp < 9.9 μm), fine (Dp < 2.5 μm), ultrafine (0.01 μm < Dp < 0.10 μm) and nano (0.01 μm < Dp < 0.056 μm) particles during hazy days were 2.8, 5.2, 5.3 and 5.1 times higher than those during non-hazy days, respectively. The in-situ pH (pHIS), as predicted by the Aerosol Inorganic Model (AIM-IV) in all sizes of PM, was observed to be lower during hazy days (average of -0.64) than that during non-hazy days (average of -0.29); there was an increased acidity in haze aerosols. Based on the measured concentrations of particulate-bound toxic elements, health risk assessment was conducted, which revealed that the excess lifetime carcinogenic risk to individuals exposed to fine particles under haze events increased significantly (P < 0.05) to 69 ± 18 × 10-6 compared to non-hazy days (34 ± 10 × 10-6). The qualitative source attribution analysis suggested that the occurrence of haze could be due to a combination of increased emissions of PM from multiple anthropogenic sources followed by its accumulation under unfavourable meteorological conditions with lower mixing heights and less wind speeds and the formation of secondary aerosols.

  3. Mass spectrometric approaches for chemical characterisation of atmospheric aerosols: critical review of the most recent advances

    SciTech Connect

    Laskin, Alexander; Laskin, Julia; Nizkorodov, Sergey A.

    2012-06-29

    This manuscript presents an overview of the most recent instrument developments for the field and laboratory applications of mass spectrometry (MS) to investigate the chemistry and physics of atmospheric aerosols. A range of MS instruments, employing different sample introduction methods, ionisation and mass detection techniques are used both for ‘online’ and ‘offline’ characterisation of aerosols. Online MS techniques enable detection of individual particles with simultaneous measurement of particle size distributions and aerodynamic characteristics and are ideally suited for field studies that require high temporal resolution. Offline MS techniques provide a means for detailed molecular-level analysis of aerosol samples, which is essential to gain fundamental knowledge regarding aerosol chemistry, mechanisms of particle formation and atmospheric aging. Combined, complementary MS techniques provide comprehensive information on the chemical composition, size, morphology and phase of aerosols – data of key importance for evaluating hygroscopic and optical properties of particles, their health effects, understanding their origins and atmospheric evolution. Over the last few years, developments and applications of MS techniques in aerosol research have expanded remarkably as evident by skyrocketing publication statistics. Finally, the goal of this review is to present the most recent developments in the field of aerosol mass spectrometry for the time period of late 2010 to early 2012, which have not been conveyed in previous reviews.

  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. Assessment of microphysical and chemical factors of aerosols over seas of the Russian Artic Eastern Section

    NASA Astrophysics Data System (ADS)

    Golobokova, Liudmila; Polkin, Victor

    2014-05-01

    The newly observed kickoff of the Northern Route development drew serious attention to state of the Arctic Resource environment. Occurring climatic and environmental changes are more sensitively seen in polar areas in particular. Air environment control allows for making prognostic assessments which are required for planning hazardous environmental impacts preventive actions. In August - September 2013, RV «Professor Khlustin» Northern Sea Route expeditionary voyage took place. En-route aerosol sampling was done over the surface of the Beringov, Chukotka and Eastern-Siberia seas (till the town of Pevek). The purpose of sampling was to assess spatio-temporal variability of optic, microphysical and chemical characteristics of aerosol particles of the surface layer within different areas adjacent to the Northern Sea Route. Aerosol test made use of automated mobile unit consisting of photoelectric particles counter AZ-10, aetalometr MDA-02, aspirator on NBM-1.2 pump chassis, and the impactor. This set of equipment allows for doing measurements of number concentration, dispersed composition of aerosols within sizes d=0.3-10 mkm, mass concentration of submicron sized aerosol, and filter-conveyed aerosols sampling. Filter-conveyed aerosols sampling was done using method accepted by EMEP and EANET monitoring networks. The impactor channel was upgraded to separate particles bigger than 1 mkm in size, and the fine grain fraction settled down on it. Reverse 5-day and 10-day trajectories of air mass transfer executed at heights of 10, 1500 and 3500 m were analyzed. The heights were selected by considerations that 3000 m is the height which characterizes air mass trend in the lower troposphere. 1500 m is the upper border of the atmospheric boundary layer, and the sampling was done in the Earth's surface layer at less than 10 m. Minimum values of the bespoken microphysical characteristics are better characteristic of higher latitudes where there are no man induced sources of

  6. Seasonal Variations of High Time-Resolved Chemical Compositions, Sources and Evolution for Atmospheric Submicron Aerosols in the Megacity of Beijing

    NASA Astrophysics Data System (ADS)

    Hu, Min; Hu, Wei; Hu, Weiwei; Zheng, Jing; Guo, Song; Wu, Yusheng; Lu, Sihua; Zeng, Limin

    2016-04-01

    This study aims to investigate aerosol secondary formation and aging process in the megacity of Beijing. Seasonal intensive campaigns were conducted from March 2012 to March 2013 at an urban site located at the campus of Peking University (116.31° E, 37.99° N). An Aerodyne high-resolution time-of-flight aerosol mass spectrometry (HR-ToF-AMS) and other relevant instrumentations for gaseous and particulate pollutants were deployed. The average submicron aerosol (PM1) mass concentrations were 45.1 ± 45.8, 37.5 ± 31.0, 41.3 ± 42.7 and 81.7 ± 72.4 μg m-3 in spring, summer, autumn and winter, respectively. Organic matter was the most abundant component, accounting for 31%, 33%, 44% and 36% in PM1 correspondingly, followed by sulfate and nitrate. Distinct seasonal and diurnal patterns of the components of PM1 tracking primary sources (e.g., BC and HOA) and secondary formation (e.g., sulfate, nitrate, ammonium, LV-OOA and SV-OOA) were significantly influenced by primary emissions and mesoscale meteorology. Combining positive matrix factorization (PMF) analysis with the mass spectrometry of organics measured by AMS, the contributions of primary and secondary sources to submicron organic aerosols (OA) were apportioned. In spring and summer, the primary sources were hydrocarbon-like OA (HOA) and cooking OA (COA), and the secondary components were low volatility (LV-OOA) and semi-volatile oxygenated OA (SV-OOA). In winter biomass burning OA (BBOA) was also resolved. In autumn, four factors were resolved, that is, OOA, HOA, COA and BBOA. In general, OOA (sum of LV-OOA and SV-OOA) was important in OA in four seasons, accounting for about 63%, 70%, 47% and 50%, respectively. SV-OOA dominated OA in summer (44%) due to the fresh secondary formation from strong photochemical oxidations; whereas, LV-OOA was dominant in OA in winter (33%), maybe because the transported air masses were more aged in heavily polluted days. The POA (sum of HOA, COA and BBOA) in OA was dominant in

  7. Coupling aerosol optics to the chemical transport model MATCH (v5.5.0) and aerosol dynamics module SALSA (v1)

    NASA Astrophysics Data System (ADS)

    Andersson, E.; Kahnert, M.

    2015-12-01

    Modelling aerosol optical properties is a notoriously difficult task due to the particles' complex morphologies and compositions. Yet aerosols and their optical properties are important for Earth system modelling and remote sensing applications. Operational optics models often make drastic and non realistic approximations regarding morphological properties, which can introduce errors. In this study a new aerosol optics model is implemented, in which more realistic morphologies and mixing states are assumed, especially for black carbon aerosols. The model includes both external and internal mixing of all chemical species, it treats externally mixed black carbon as fractal aggregates, and it accounts for inhomogeneous internal mixing of black carbon by use of a novel "core-grey shell" model. Simulated results of radiative fluxes, backscattering coefficients and the Ångström exponent from the new optics model are compared with results from another model simulating particles as externally mixed homogeneous spheres. To gauge the impact on the optical properties from the new optics model, the known and important effects from using aerosol dynamics serves as a reference. The results show that using a more detailed description of particle morphology and mixing states influences the optical properties to the same degree as aerosol dynamics. This is an important finding suggesting that over-simplified optics models coupled to a chemical transport model can introduce considerable errors; this can strongly effect simulations of radiative fluxes in Earth-system models, and it can compromise the use of remote sensing observations of aerosols in model evaluations and chemical data assimilation.

  8. Chemical Compositions of Stars

    NASA Astrophysics Data System (ADS)

    Leckrone, D.; Murdin, P.

    2000-11-01

    In 1835, in a famously inaccurate forecast, the French philosopher Auguste Comte wrote of stars that, `We understand the possibility of determining their shapes, their distances, their sizes and their movements; whereas we would never know how to study by any means their chemical composition…'. At the close of the 20th century the accurate measurement of the abundances of the chemical elements in...

  9. Physico-chemical properties of aerosols in Sao Paulo, Brazil and mechanisms of secondary organic aerosol formation.

    NASA Astrophysics Data System (ADS)

    Artaxo, Paulo; Ferreira de Brito, Joel; Varanda Rizzo, Luciana; Luiza Godoy, Maria; Godoy, Jose Marcus

    2013-04-01

    Megacities emissions are increasingly becoming a global issue, where emissions from the transportation sector play an increasingly important role. Sao Paulo is a megacity with a population of about 18 million people, 7 million cars and large-scale industrial emissions. As a result of the vehicular and industrial emissions, the air quality in Sao Paulo is bellow WMO standards for aerosol particles and ozone. Many uncertainties are found on gas- and particulate matter vehicular emission factors and their following atmospheric processes, e.g. secondary organic aerosol formation. Due to the uniqueness of the vehicular fuel in Brazil, largely based on ethanol use, such characterization currently holds further uncertainties. To improve the understanding of the role of this unique emission characteristics, we are running a source apportionment study in Sao Paulo focused on the mechanisms of organic aerosol formation. One of the goals of this study is a quantitative aerosol source apportionment focused on vehicular emissions, including ethanol and gasohol (both fuels used by light-duty vehicles). This study comprises four sampling sites with continuous measurements for one year, where trace elements and organic aerosol are being measured for PM2.5 and PM10 along with real-time NOx, O3, PM10 and CO measurements. Aerosol optical properties and size distribution are being measured on a rotation basis between sampling stations. Furthermore, a Proton-Transfer-Reaction Mass Spectrometer (PTR-MS) and an Aerosol Chemical Speciation Monitor (ACSM) are used to measure in real time VOCs and aerosol composition, respectively. Trace elements were measured using XRF and OC/EC analysis was determined with a Sunset OC/EC instrument. A TSI Nephelometer with 3 wavelengths measure light scattering and a MAAP measure black carbon. Results show aerosol number concentrations ranging between 10,000 and 35,000 cm-3, mostly concentrated in the nucleation and Aitken modes, with a peak in size at 80

  10. 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.

  11. 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

  12. Variability of aerosols and chemical composition of PM10, PM2.5 and PM1 on a platform of the Prague underground metro

    NASA Astrophysics Data System (ADS)

    Cusack, M.; Talbot, N.; Ondráček, J.; Minguillón, M. C.; Martins, V.; Klouda, K.; Schwarz, J.; Ždímal, V.

    2015-10-01

    Measurements of PM10, PM2.5 and PM1 and particle number concentration and size distribution were measured for 24 h on a platform of the Prague underground metro in October 2013. The three PM fractions were analysed for major and minor elements, secondary inorganic aerosols (SIA) and total carbon (TC). Measurements were performed both when the metro was inoperative and closed to the public (referred to as background), and when the metro was in operation and open to passengers. PM concentrations were elevated during both periods, but were substantially increased in the coarse fraction during hours when the metro was in operation. Average PM concentrations were 214.8, 93.9 and 44.8 μg m-3 for PM10, PM2.5 and PM1, respectively (determined gravimetrically). Average particle number concentrations were 8.5 × 103 cm-3 for background hours and 11.5 × 103 cm-3 during operational hours. Particle number concentrations were found to not vary as significantly as PM concentrations throughout the day. Variations in PM were strongly governed by passing trains, with highest concentrations recorded during rush hour. When trains were less frequent, PM concentrations were shown to fluctuate in unison with the entrance and exit of trains (as shown by wind velocity measured on the platform). PM was found to be highly enriched with iron, especially in the coarse fraction, comprising 46% of PM10 (98.9 μg m-3). This reduces to 6.7 μg m-3 during background hours, proving that the trains themselves were the main source of iron, most probably from wheel-rail mechanical abrasion. Other enriched elements relative to background hours included Ba, Cu, Mn, Cr, Mo, Ni and Co, among others. Many of these elements exhibited a similar size distribution, further indicating their sources were common and were attributed to train operations.

  13. 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.

  14. 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.

  15. Method of forming a chemical composition

    DOEpatents

    Bingham, Dennis N.; Wilding, Bruce M.; Klingler, Kerry M.; Zollinger, William T.; Wendt, Kraig M.

    2007-10-09

    A method of forming a chemical composition such as a chemical hydride is described and which includes the steps of selecting a composition having chemical bonds and which is capable of forming a chemical hydride; providing a source of hydrogen; and exposing the selected composition to an amount of ionizing radiation to encourage the changing of the chemical bonds of the selected composition, and chemically reacting the selected composition with the source of hydrogen to facilitate the formation of a chemical hydride.

  16. 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

  17. Aerosol Composition in Los Angeles During the 2010 CalNex Campaign Studied by High Resolution Aerosol Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Hayes, P. L.; Ortega, A. M.; Cubison, M.; Hu, W.; Toohey, D. W.; Flynn, J. H.; Grossberg, N.; Lefer, B. L.; Alvarez, S.; Rappenglueck, B.; Allan, J. D.; McKeen, S. A.; Holloway, J. S.; Gilman, J. B.; Kuster, W. C.; Graus, M.; Warneke, C.; de Gouw, J. A.; Richter, R.; Hofer, J.; Prevot, A. S.; Jimenez, J. L.

    2010-12-01

    Submicron atmospheric aerosols impact climate and human health, but their sources and composition are poorly understood. To address this knowledge gap, high-resolution time-of-flight aerosol mass spectrometry (AMS) [DeCarlo et al. Anal. Chem. 2006] and other advanced instrumentation were deployed during the CalNex field campaign in May and June 2010 for 4 weeks to characterize the composition of aerosols in the Los Angeles area. Utilizing AMS, the concentrations for both organic and non-refractory inorganic (sulfate, nitrate, ammonium, chloride) submicron aerosols were quantified at the Caltech/Pasadena ground site 15 km NE of downtown Los Angeles. The total submicron mass concentration as well as the species concentrations measured by AMS compare well with other instruments. Nitrate aerosols appear to dominate in the cooler mornings, but their concentration is reduced in the afternoon when organic aerosols (OA) increase and dominate. The diurnal variations in concentration are strongly influenced by vertical dilution from the rising planetary boundary layer in the afternoon. Secondary organic aerosols (SOA) are an important fraction of submicron aerosols. To assess the concentrations of different OA components present at the site, positive matrix factorization (PMF) is used to analyze the field data. The major OA classes are oxygenated OA (OOA, a surrogate for total SOA), and hydrocarbon-like OA (HOA, a surrogate for primary combustion OA). Preliminary PMF analysis finds that OOA is consistently the largest type of OA present (~75% of the total OA concentration). This result suggests that the air mass over the site has undergone substantial chemical aging. The correlations between OOA and Ox (O3 + NO2) concentrations, as well as between HOA, CO and black carbon concentrations are strong and consistent with previous studies. AMS and 14C measurements are combined to determine the fractions of HOA and OOA from non-fossil vs. fossil sources. Using measurements of SOA

  18. 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

  19. 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

  20. Modelling the optical properties of aerosols in a chemical transport model

    NASA Astrophysics Data System (ADS)

    Andersson, E.; Kahnert, M.

    2015-12-01

    According to the IPCC fifth assessment report (2013), clouds and aerosols still contribute to the largest uncertainty when estimating and interpreting changes to the Earth's energy budget. Therefore, understanding the interaction between radiation and aerosols is both crucial for remote sensing observations and modelling the climate forcing arising from aerosols. Carbon particles are the largest contributor to the aerosol absorption of solar radiation, thereby enhancing the warming of the planet. Modelling the radiative properties of carbon particles is a hard task and involves many uncertainties arising from the difficulties of accounting for the morphologies and heterogeneous chemical composition of the particles. This study aims to compare two ways of modelling the optical properties of aerosols simulated by a chemical transport model. The first method models particle optical properties as homogeneous spheres and are externally mixed. This is a simple model that is particularly easy to use in data assimilation methods, since the optics model is linear. The second method involves a core-shell internal mixture of soot, where sulphate, nitrate, ammonia, organic carbon, sea salt, and water are contained in the shell. However, by contrast to previously used core-shell models, only part of the carbon is concentrated in the core, while the remaining part is homogeneously mixed with the shell. The chemical transport model (CTM) simulations are done regionally over Europe with the Multiple-scale Atmospheric Transport and CHemistry (MATCH) model, developed by the Swedish Meteorological and Hydrological Institute (SMHI). The MATCH model was run with both an aerosol dynamics module, called SALSA, and with a regular "bulk" approach, i.e., a mass transport model without aerosol dynamics. Two events from 2007 are used in the analysis, one with high (22/12-2007) and one with low (22/6-2007) levels of elemental carbon (EC) over Europe. The results of the study help to assess the

  1. Detailed Chemical Characterization of Unresolved Complex Mixtures (UCM) inAtmospheric Organics: Insights into Emission Sources, Atmospheric Processing andSecondary Organic Aerosol Formation

    EPA Science Inventory

    Recent studies suggest that semivolatile organic compounds (SVOCs) are important precursors to secondary organic aerosol (SOA) in urban atmospheres. However, knowledge of the chemical composition of SVOCs is limited by current analytical techniques, which are typically unable to...

  2. 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.

  3. Three Compact, Robust Chemical Characterization Systems Suited To Sensitive, High Time Resolution Measurements Of Atmospheric Aerosols

    NASA Astrophysics Data System (ADS)

    Barrie, L. A.; Cowin, J. P.; Worsnop, D. R.

    2001-12-01

    In the past decade, the advancement of compact, robust and sensitive instrumentation to measure the chemical characteristics of atmospheric aerosols has lagged behind their physical characterization. There is a need for chemical instrumentation with these three qualities for use on airborne platforms and at infrequently attended ground level surveillance sites. Now chemical techniques are appearing that promise to fill this need. We discuss three chemical characterization systems that are emerging in atmospheric chemistry and climate research applications. These are: (i) the Aerodyne mass spectrometer for real time measurement of particle composition and two post-collection analysis techniques (ii) non-destructive, multi-elemental chemical analysis of size-resolved samples by high spatial resolution synchrotron x-ray and proton beams (S-XRF/PIXE/PESA/STIM) (iii) single particle characterization by automated scanning electron microscopy with energy-dispersed detection of X-rays (SEM/EDX). The key to post-collection analysis is automated aerosol sizing and collection systems and automated chemical analysis systems. Together these techniques provide unique, comprehensive information on the organic and inorganic composition and morphology of particles and yet are easy to deploy in the field. The sensitivity of each technique is high enough to permit the rapid sampling needed to resolve spatial gradients in composition from a moving platform like the Battelle Gulfstream-159 aircraft, traveling at 100m/s.

  4. Chemical composition of Mars

    USGS Publications Warehouse

    Morgan, J.W.; Anders, E.

    1979-01-01

    The composition of Mars has been calculated from the cosmochemical model of Ganapathy and Anders (1974) which assumes that planets and chondrites underwent the same 4 fractionation processes in the solar nebula. Because elements of similar volatility stay together in these processes, only 4 index elements (U, Fe, K and Tl or Ar36) are needed to calculate the abundances of all 83 elements in the planet. The values chosen are U = 28 ppb, K = 62 ppm (based on K U = 2200 from orbital ??-spectrometry and on thermal history calculations by Tokso??z and Hsui (1978) Fe = 26.72% (from geophysical data), and Tl = 0.14 ppb (from the Ar36 and Ar40 abundances measured by Viking). The mantle of Mars is an iron-rich [Mg/(Mg + Fe) = 0.77] garnet wehrlite (?? = 3.52-3.54 g/cm3), similar to McGetchin and Smyth's (1978) estimate but containing more Ca and Al. It is nearly identical to the bulk Moon composition of Morgan et al. (1978b). The core makes up 0.19 of the planet and contains 3.5% S-much less than estimated by other models. Volatiles have nearly Moon-like abundances, being depleted relative to the Earth by factors of 0.36 (K-group, Tcond = 600-1300 K) or 0.029 (Tl group, Tcond < 600 K). The water abundance corresponds to a 9 m layer, but could be higher by as much as a factor of 11. Comparison of model compositions for 5 differentiated planets (Earth, Venus, Mars, Moon, and eucrite parent body) suggests that volatile depletion correlates mainly with size rather than with radial distance from the Sun. However, the relatively high volatile content of shergottites and some chondrites shows that the correlation is not simple; other factors must also be involved. ?? 1979.

  5. 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.

  6. 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

    Popular summary: Atmospheric aerosols play an important role in the Earth's climate system, and can also have adverse effects on air quality and human health. The environmental impacts of aerosols, on the other hand, are highly regional, since their temporal/spatial distribution is inhomogeneous and highly depends on the regional emission sources. To better understand the effects of aerosols, intensive field experiments are necessary to characterize the chemical and physical properties on a region-by-region basis. From late February to early May in 2006, NASA/GSFC's SMARTLabs facility was deployed at a rural site in central Thailand, Southeast Asia, to conduct a field experiment dubbed BASE-ASIA (Biomass-burning Aerosols in South East-Asia: Smoke Impact Assessment). The group was joined by scientists from the University of Hawaii and other regional institutes. Comprehensive measurements were made during the experiment, including aerosol chemical composition, optical and microphysical properties, as well as surface energetics and local . meteorology. This study analyzes part of the data from the BASE-ASIA experiment. It was found that, even for the relatively remote rural site, the aerosol loading was still substantial. Besides agricultural burning in the area, industrial pollution near the Bangkok metropolitan area, about 200 km southeast of the site, and even long-range transport from China, also contribute to the area's aerosol loading. The 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. Abstract: Comprehensive measurements of atmospheric aerosols were made in Phimai, central Thailand (15.l83 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(exp -1); absorption: 15

  7. 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.

  8. 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

  9. 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.

  10. Physical Chemical Studies on Molecular Composite Compositions

    DTIC Science & Technology

    1993-02-20

    McCrone , L. B., Deity, J. G., Polarized Light Microscopy, McCrone Research Institute, Chicago (1987). 32. Wolfe, W. L., In Handbook of Optics, Optical...are discussed. The rheology of miscible blends of the rodlike chains with flexibie or semiflexible chains is discussed using a model accounting for...vii PHYSICAL- CHEMICAL STUDIES ON RODLIKE POLYMER COMPOSITIONS The following is a final report for work of AFOSR-89--0125, covering the period January

  11. Bringing the ocean into the laboratory to probe the chemical complexity of sea spray aerosol

    PubMed Central

    Prather, Kimberly A.; Bertram, Timothy H.; Grassian, Vicki H.; Deane, Grant B.; Stokes, M. Dale; DeMott, Paul J.; Aluwihare, Lihini I.; Palenik, Brian P.; Azam, Farooq; Seinfeld, John H.; Moffet, Ryan C.; Molina, Mario J.; Cappa, Christopher D.; Geiger, Franz M.; Roberts, Gregory C.; Russell, Lynn M.; Ault, Andrew P.; Baltrusaitis, Jonas; Collins, Douglas B.; Corrigan, Craig E.; Cuadra-Rodriguez, Luis A.; Ebben, Carlena J.; Forestieri, Sara D.; Guasco, Timothy L.; Hersey, Scott P.; Kim, Michelle J.; Lambert, William F.; Modini, Robin L.; Mui, Wilton; Pedler, Byron E.; Ruppel, Matthew J.; Ryder, Olivia S.; Schoepp, Nathan G.; Sullivan, Ryan C.; Zhao, Defeng

    2013-01-01

    The production, size, and chemical composition of sea spray aerosol (SSA) particles strongly depend on seawater chemistry, which is controlled by physical, chemical, and biological processes. Despite decades of studies in marine environments, a direct relationship has yet to be established between ocean biology and the physicochemical properties of SSA. The ability to establish such relationships is hindered by the fact that SSA measurements are typically dominated by overwhelming background aerosol concentrations even in remote marine environments. Herein, we describe a newly developed approach for reproducing the chemical complexity of SSA in a laboratory setting, comprising a unique ocean-atmosphere facility equipped with actual breaking waves. A mesocosm experiment was performed in natural seawater, using controlled phytoplankton and heterotrophic bacteria concentrations, which showed SSA size and chemical mixing state are acutely sensitive to the aerosol production mechanism, as well as to the type of biological species present. The largest reduction in the hygroscopicity of SSA occurred as heterotrophic bacteria concentrations increased, whereas phytoplankton and chlorophyll-a concentrations decreased, directly corresponding to a change in mixing state in the smallest (60–180 nm) size range. Using this newly developed approach to generate realistic SSA, systematic studies can now be performed to advance our fundamental understanding of the impact of ocean biology on SSA chemical mixing state, heterogeneous reactivity, and the resulting climate-relevant properties. PMID:23620519

  12. Aerosol Physical and Chemical Properties Before and After the Manaus Plume in the GoAmazon2014 Experiment

    NASA Astrophysics Data System (ADS)

    Artaxo, P.; Barbosa, H. M.; Ferreira De Brito, J.; Wurm, F.; Holanda, B. A.; Carbone, S.; Arana, A.; Cirino, G. G.; Souza, R. A. F. D.; Rizzo, L. V.; Martin, S. T.; Andreae, M. O.; Holben, B. N.; Schafer, J.

    2014-12-01

    As part of the GoAmazon2014 experiment, several aerosol and trace gas monitoring stations are being operated for at least one year before and after the Manaus plume. Three sites are being operated in pristine conditions, with atmospheric properties under natural biogenic conditions. These three sites called T0 are: ATTO (Amazon Tall Tower Observatory), ZF2 ecological research site and a third site called EMBRAPA. After the air masses are exposed to the Manaus plume, one site (called T2) is being operated right on the opposite side of the Negro River under the direct influence of the Manaus plume at 5 Km downwind of Manaus. Finally, at about 150 Km downwind of Manaus is the T3 Manacapuru site. Aerosol chemical composition is being analyzed using filters for fine (PM2.5) and coarse mode aerosol as well as three Aerodyne ACSM (Aerosol Chemical Speciation Monitors) instruments. Aerosol absorption is being studied with several aethalometers and MAAP (Multi Angle Absorption Photometers). Aerosol light scattering are being measured at several wavelengths using nephelometers. Aerosol size distribution is determined using scanning mobility particle sizers. The aerosol column is measures using AERONET sunphotometers before and after the Manaus plume, as well as several Lidar systems. The three sites before the Manaus plume show remarkable similar variability in aerosol concentrations and optical properties. This pattern is very different at the T2 site, with large aerosol concentrations enhancing aerosol absorption and scattering significantly. The aerosol is very oxidized before being exposed to the Manaus plume, and this pattern changes significantly for T2 and T3 sites, with a much higher presence of less oxidized aerosol. Typical ozone concentrations at mid-day before Manaus plume is a low 10-12 ppb, value that changes to 50-70 ppb for air masses suffering the influence of Manaus plume. A detailed comparison of aerosol characteristics and composition for the several

  13. The Chemical Composition of Honey

    ERIC Educational Resources Information Center

    Ball, David W.

    2007-01-01

    Honey is a supersaturated sugar solution, created by bees, and used by human beings as a sweetener. However, honey is more than just a supersaturated sugar solution; it also contains acids, minerals, vitamins, and amino acids in varying quantities. In this article, we will briefly explore the chemical composition of honey. (Contains 2 figures and…

  14. Chemical recycling of scrap composites

    NASA Technical Reports Server (NTRS)

    Allred, Ronald E.; Salas, Richard M.

    1994-01-01

    There are no well-developed technologies for recycling composite materials other than grinding to produce fillers. New approaches are needed to reclaim these valuable resources. Chemical or tertiary recycling, conversion of polymers into low molecular weight hydrocarbons for reuse as chemicals or fuels, is emerging as the most practical means for obtaining value from waste plastics and composites. Adherent Technologies is exploring a low-temperature catalytic process for recycling plastics and composites. Laboratory results show that all types of plastics, thermosets as well as thermoplastics, can be converted in high yields to valuable hydrocarbon products. This novel catalytic process runs at 200 C, conversion times are rapid, the process is closed and, thus, nonpolluting, and no highly toxic gas or liquid products have been observed so no negative environmental impact will result from its implementation. Tests on reclamation of composite materials show that epoxy, imide, and engineering thermoplastic matrices can be converted to low molecular weight hydrocarbons leaving behind the reinforcing fibers for reuse as composite reinforcements in secondary, lower-performance applications. Chemical recycling is also a means to dispose of sensitive or classified organic materials without incineration and provides a means to eliminate or reduce mixed hazardous wastes containing organic materials.

  15. Aerosol accumulation intensity and composition variations under different weather conditions in urban environment

    NASA Astrophysics Data System (ADS)

    Steinberga, Iveta; Bikshe, Janis; Eindorfa, Aiva

    2014-05-01

    During the last decade aerosol (PM10, PM2.5) mass and composition measurements were done in different urban environments - parallel street canyons, industrial sites and at the background level in Riga, Latvia. Effect of meteorological parameters on the accumulation and ventilation intensity was investigated in order to understand microclimatological parameters affecting aerosol pollution level and chemical composition changes. In comparison to industrial sites (shipping activities, bulk cargo, oil and naphtha processing), urban street canyon aerosol mass concentration was significantly higher, for PM10 number of daily limit exceedances are higher by factor 3.4 - 3.9 in street canyons. Exceedances of PM2.5 annual limits were identified only in street canyons as well. Precipitation intensity, wind speed, days with mist highly correlates with aerosol concentration; in average during the year about 1 - 2 % presence of calm wind days, 20 - 30 days with mist facilitate accumulation of aerosols and mitigating growing of secondary aerosols. It has been assessed that about 25 % of daily exceedances in street canyons are connected with sea salt/street sanding factor. Strong dependency of wind speed and direction were identified in winter time - low winds (0.4 - 1.7 m/s) blowing from south, south-east (cross section of the street) contributing to PM10 concentrations over 100 - 150 ug/m3. Seasonal differences in aerosol concentrations were identified as a result of recombination of direct source impact, specific meteorological and synoptical conditions during the period from January until April when usually dominates extremely high aerosol concentrations. While aerosol mass concentration levels in monitoring sites significantly differs, concentrations of heavy metals (Pb, Ni, Cd, and As) are almost at the same level, even more - concentration of Cd for some years was higher in industrial area where main pollution is caused by oil processing and storage, heavy traffic

  16. High resolution simulations of aerosol microphysics in a global and regionally nested chemical transport model

    NASA Astrophysics Data System (ADS)

    Adams, P. J.; Marks, M.

    2015-12-01

    The aerosol indirect effect is the largest source of forcing uncertainty in current climate models. This effect arises from the influence of aerosols on the reflective properties and lifetimes of clouds, and its magnitude depends on how many particles can serve as cloud droplet formation sites. Assessing levels of this subset of particles (cloud condensation nuclei, or CCN) requires knowledge of aerosol levels and their global distribution, size distributions, and composition. A key tool necessary to advance our understanding of CCN is the use of global aerosol microphysical models, which simulate the processes that control aerosol size distributions: nucleation, condensation/evaporation, and coagulation. Previous studies have found important differences in CO (Chen, D. et al., 2009) and ozone (Jang, J., 1995) modeled at different spatial resolutions, and it is reasonable to believe that short-lived, spatially-variable aerosol species will be similarly - or more - susceptible to model resolution effects. The goal of this study is to determine how CCN levels and spatial distributions change as simulations are run at higher spatial resolution - specifically, to evaluate how sensitive the model is to grid size, and how this affects comparisons against observations. Higher resolution simulations are necessary supports for model/measurement synergy. Simulations were performed using the global chemical transport model GEOS-Chem (v9-02). The years 2008 and 2009 were simulated at 4ox5o and 2ox2.5o globally and at 0.5ox0.667o over Europe and North America. Results were evaluated against surface-based particle size distribution measurements from the European Supersites for Atmospheric Aerosol Research project. The fine-resolution model simulates more spatial and temporal variability in ultrafine levels, and better resolves topography. Results suggest that the coarse model predicts systematically lower ultrafine levels than does the fine-resolution model. Significant

  17. Active and passive smoking - New insights on the molecular composition of different cigarette smoke aerosols by LDI-FTICRMS

    NASA Astrophysics Data System (ADS)

    Schramm, Sébastien; Carré, Vincent; Scheffler, Jean-Luc; Aubriet, Frédéric

    2014-08-01

    The aerosol generated when a cigarette is smoked is a significant indoor contaminant. Both smokers and non-smokers can be exposed to this class of pollutants. Nevertheless, they are not exposed to the same kind of smoke. The active smoker breathes in the mainstream smoke (MSS) during a puff, whereas the passive smoker inhales not only the smoke generated by the lit cigarette between two puffs (SSS) but also the smoke exhaled by active smokers (EXS). The aerosol fraction of EXS has until now been poorly documented; its composition is expected to be different from MSS. This study aims to investigate the complex composition of aerosol from EXS to better understand the difference in exposure between active and passive smokers. To address this, the in-situ laser desorption ionisation Fourier transform ion cyclotron mass spectrometry (LDI-FTICRMS) was used to characterise the aerosol composition of EXS from two different smokers. Results clearly indicated many similarities between EXS samples but also significant differences with MSS and SSS aerosol. The comparison of MSS and EXS aerosol allowed the chemicals retained by the active smoker's lungs to be identified, whereas the convolution of the EXS and SSS aerosol compositions were considered relevant to the exposition of a passive smoker. As a consequence, active smokers are thought to be mainly exposed to polar and poorly unsaturated oxygenated and nitrogenated organics, compared with poorly oxygenated but highly unsaturated compounds in passive smokers.

  18. Aerosols and clouds in chemical transport models and climate models.

    SciTech Connect

    Lohmann,U.; Schwartz, S. E.

    2008-03-02

    Clouds exert major influences on both shortwave and longwave radiation as well as on the hydrological cycle. Accurate representation of clouds in climate models is a major unsolved problem because of high sensitivity of radiation and hydrology to cloud properties and processes, incomplete understanding of these processes, and the wide range of length scales over which these processes occur. Small changes in the amount, altitude, physical thickness, and/or microphysical properties of clouds due to human influences can exert changes in Earth's radiation budget that are comparable to the radiative forcing by anthropogenic greenhouse gases, thus either partly offsetting or enhancing the warming due to these gases. Because clouds form on aerosol particles, changes in the amount and/or composition of aerosols affect clouds in a variety of ways. The forcing of the radiation balance due to aerosol-cloud interactions (indirect aerosol effect) has large uncertainties because a variety of important processes are not well understood precluding their accurate representation in models.

  19. 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.

  20. Chemical Characterization of the Aerosol During the CLAMS Experiment Using Aircraft and Ground Stations

    NASA Astrophysics Data System (ADS)

    Castanho, A. D.; Martins, J.; Artaxo, P.; Hobbs, P. V.; Remer, L.; Yamasoe, M.; Fattori, A.

    2002-05-01

    During the Chesapeake Lighthouse and Aircraft Measurements for Satellites (CLAMS) Experiment Nuclepore filters were collected in two ground stations and aboard the University of Wasghington's Convair 580 Reserarch Aircraft. The two ground stations were chosen in strategic positions to characterize the chemical composition, the mass concentration, black carbon (BC) content, and the absorption properties of the aerosol particles at the surface level. One of the stations was located at the Cheasapeake lighthouse (25 km from the coast) and the other one was located at the Wallops Island. Aerosol particles where collected in two stages, fine (d<2.5um) and coarse mode (2.5composition, mass concentration, BC content, and absorption properties of the aerosol in the atmospheric column in the CLAMS Experiment area. Some of the filters were also submitted to Scanning Electron Microscopy analysis. The particulate matter mass for all the samples were obtained gravimetrically. The concentration of black carbon in the fine filters was optically determined by a broadband reflectance technique. The spectral (from UV to near IR) reflectance in the fine and coarse mode filter were also obtained with a FieldSpec ASD spectrometer. Aerosol elemental characterization (Na through Pb) was obtained by the PIXE (Particle induced X ray emission) analyses of the nuclepore filters. The sources of the aerosol measured at the ground stations were estimated by principal component analyses mainly in the Wallops Island, where a longer time series was collected. One of the main urban components identified in the aerosol during the experiment was sulfate. Black carbon

  1. Chemical compositions, methods of making the chemical compositions, and structures made from the chemical compositions

    DOEpatents

    Yang, Lei; Cheng, Zhe; Liu, Ze; Liu, Meilin

    2015-01-13

    Embodiments of the present disclosure include chemical compositions, structures, anodes, cathodes, electrolytes for solid oxide fuel cells, solid oxide fuel cells, fuel cells, fuel cell membranes, separation membranes, catalytic membranes, sensors, coatings for electrolytes, electrodes, membranes, and catalysts, and the like, are disclosed.

  2. 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.

  3. Optical and Chemical Characterization of Aerosols Produced from Cooked Meats

    NASA Astrophysics Data System (ADS)

    Niedziela, R. F.; Foreman, E.; Blanc, L. E.

    2011-12-01

    Cooking processes can release a variety compounds into the air immediately above a cooking surface. The distribution of compounds will largely depend on the type of food that is being processed and the temperatures at which the food is prepared. High temperatures release compounds from foods like meats and carry them away from the preparation surface into cooler regions where condensation into particles can occur. Aerosols formed in this manner can impact air quality, particularly in urban areas where the amount of food preparation is high. Reported here are the results of laboratory experiments designed to optically and chemically characterize aerosols derived from cooking several types of meats including ground beef, salmon, chicken, and pork both in an inert atmosphere and in synthetic air. The laboratory-generated aerosols are studied using a laminar flow cell that is configured to accommodate simultaneous optical characterization in the mid-infrared and collection of particles for subsequent chemical analysis by gas chromatography. Preliminary optical results in the visible and ultra-violet will also be presented.

  4. Uncertainties of simulated aerosol optical properties induced by assumptions on aerosol physical and chemical properties: an AQMEII-2 perspective

    EPA Science Inventory

    The calculation of aerosol optical properties from aerosol mass is a process subject to uncertainty related to necessary assumptions on the treatment of the chemical species mixing state, density, refractive index, and hygroscopic growth. In the framework of the AQMEII-2 model in...

  5. 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.

  6. 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

  7. 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.

  8. SPACCIM simulations of chemical aerosol-cloud interactions with the multiphase chemical mechanism MCM-CAPRAM3.0i

    NASA Astrophysics Data System (ADS)

    Tilgner, A.; Schrödner, R.; Bräuer, P.; Wolke, R.; Herrmann, H.

    2010-07-01

    Heterogeneous and multiphase processes in fog droplets, cloud droplets and deliquescent particles can potentially alter the physico-chemical composition of the tropospheric aerosol on global scale. In order to model such complex tropospheric multiphase chemical interactions of clouds, fogs and deliquescent aerosol particles, chemical mechanisms with a detailed description of chemical processes in both the gas and aqueous phase are required. Currently, both near-explicit gas and aqueous phase mechanisms are available. However, a near-explicit chemical multiphase mechanism was still missing. Therefore, the near-explicit chemical gas phase mechanism MCM v3 (Master Chemical Mechanism, Saunder et al., 2003) with about 13502 reactions and the explicit aqueous phase mechanism CAPRAM3.0i (Chemical Aqueous Phase Radical Mechanism, Herrmann et al., 2005) with about 777 reactions were coupled and integrated into the model framework SPACCIM (SPectral Aerosol Cloud Chemistry Interaction Model; Wolke et al., 2005). The parcel model SPACCIM combines a complex microphysical and multiphase chemistry model. First SPACCIM simulations have been carried out for different environmental conditions using a non-permanent cloud scenario. The model studies were aimed to investigate multiphase chemistry in tropospheric deliquescent aerosol particles, fogs and clouds in more detail. The model investigations were focused on the multiphase chemistry of tropospheric radical oxidants such as OH and NO3, organic compounds and closely linked chemical subsystems. The model results have been analysed including time-resolved reaction flux analyses. The obtained model results of the near-explicit multiphase mechanism MCM-CAPRAM3.0i have been compared with results of former model studies using the non-explicit gas phase mechanism RACM-MIM2ext and CAPRAM3.0i (Tilgner and Herrmann, 2010). Herrmann, H., Tilgner, A., Barzaghi, P., Majdik, Z., Gligorovski, S., Poulain, L., and Monod, A.: Towards a more

  9. 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

  10. Quantifying compositional impacts of ambient aerosol on cloud droplet formation

    NASA Astrophysics Data System (ADS)

    Lance, Sara

    It has been historically assumed that most of the uncertainty associated with the aerosol indirect effect on climate can be attributed to the unpredictability of updrafts. In Chapter 1, we analyze the sensitivity of cloud droplet number density, to realistic variations in aerosol chemical properties and to variable updraft velocities using a 1-dimensional cloud parcel model in three important environmental cases (continental, polluted and remote marine). The results suggest that aerosol chemical variability may be as important to the aerosol indirect effect as the effect of unresolved cloud dynamics, especially in polluted environments. We next used a continuous flow streamwise thermal gradient Cloud Condensation Nuclei counter (CCNc) to study the water-uptake properties of the ambient aerosol, by exposing an aerosol sample to a controlled water vapor supersaturation and counting the resulting number of droplets. In Chapter 2, we modeled and experimentally characterized the heat transfer properties and droplet growth within the CCNc. Chapter 3 describes results from the MIRAGE field campaign, in which the CCNc and a Hygroscopicity Tandem Differential Mobility Analyzer (HTDMA) were deployed at a ground-based site during March, 2006. Size-resolved CCN activation spectra and growth factor distributions of the ambient aerosol in Mexico City were obtained, and an analytical technique was developed to quantify a probability distribution of solute volume fractions for the CCN in addition to the aerosol mixing-state. The CCN were shown to be much less CCN active than ammonium sulfate, with water uptake properties more consistent with low molecular weight organic compounds. The pollution outflow from Mexico City was shown to have CCN with an even lower fraction of soluble material. "Chemical Closure" was attained for the CCN, by comparing the inferred solute volume fraction with that from direct chemical measurements. A clear diurnal pattern was observed for the CCN solute

  11. Chemical composition of lunar material.

    PubMed

    Maxwell, J A; Abbey, S; Champ, W H

    1970-01-30

    Chemical and emission spectrographic analyses of three Apollo 11 samples, 10017-29, 10020-30, and 10084-132, are given. Major and minor constituents were determined both by conventional rock analysis methods and by a new composite scheme utilizing a lithium fluoborate method for dissolution of the samples and atomic absorption spectroscopy and colorimetry. Trace constituents were determined by optical emission spectroscopy involving a d-c arc, air-jet controlled.

  12. 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).

  13. Nature, Origin, Potential Composition, and Climate Impact of the Asian Tropopause Aerosol Layer (ATAL)

    NASA Technical Reports Server (NTRS)

    Fairlie, T. D.; Vernier, J.-P.; Thomason, L. W.; Natarajan, M.; Bedka, K.; Wienhold, F.; Bian J.; Martinsson, B.

    2015-01-01

    Satellite observations from SAGE II and CALIPSO indicate that summertime aerosol extinction has more than doubled in the Asian Tropopause Aerosol Layer (ATAL) since the late 1990s. Here we show remote and in-situ observations, together with results from a chemical transport model (CTM), to explore the likely composition, origin, and radiative forcing of the ATAL. We show in-situ balloon measurements of aerosol backscatter, which support the high levels observed by CALIPSO since 2006. We also show in situ measurements from aircraft, which indicate a predominant carbonaceous contribution to the ATAL (Carbon/Sulfur ratios of 2- 10), which is supported by the CTM results. We show that the peak in ATAL aerosol lags by 1 month the peak in CO from MLS, associated with deep convection over Asia during the summer monsoon. This suggests that secondary formation and growth of aerosols in the upper troposphere on monthly timescales make a significant contribution to ATAL. Back trajectory calculations initialized from CALIPSO observations provide evidence that deep convection over India is a significant source for ATAL through the vertical transport of pollution to the upper troposphere.

  14. 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.

  15. 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.

  16. Seasonal contrast in aerosol abundance over northern south Asia using a chemical transport model

    NASA Astrophysics Data System (ADS)

    Venkataraman, C.; Sadavarte, P.; Madhavan, B. L.; Kulkarni, S.; Carmichael, G. R.; Adhikary, B.; D'Allura, A.; Cherian, R.; Das, S.; Gupta, T.; Streets, D. G.; Wei, C.; Zhang, Q.

    2012-12-01

    Northern South-Asia, home to about half a billion people, experiences large aerosol abundances almost all year around. There are gaps in our understanding of seasonal variations in regional aerosol emissions, abundance and radiative effects. The present study uses chemical transport model simulations (at ~ 60km resolution), with regionally estimated emissions, to investigate the contrast in aerosol surface and columnar abundance during pre-monsoon transition, monsoon and inter-monsoon transition periods over than Gangetic plain (GP) and Tibetan plateau. The interplay between aerosol emissions and atmospheric transport is examined to explain the variability. Model predictions were evaluated with available in-situ measurements and AOD from AERONET and MODIS level-2 retrievals (at 10 km resolution) processed with quality weighting to the model resolution. During April, AOD was dominated by dust at most sites across the GP and Tibet. However, AOD from organic carbon (emitted from agricultural residue burning) is also significant at several sites (Pantnagar, Godavari, Kolkata, Dhaka, and at high altitude Pyramid and Lhasa sites), consistent with recently reported MISR climatology in this region. In contrast, during July and September, AOD was dominated by sulfate at all sites. In April, aerosols over the GP could be attributed to emissions from large industrial sources (thermal power plant, cement industries, iron & steel and other industries) and agricultural residue burning transported from the northwest, along with forest burning emissions transported from the east. Large fluxes of open burning emissions in the east GP, along with prevailing easterly wind flow into the GP led to an east-west gradient in anthropogenic aerosols. During July, there was little open burning, so aerosol concentrations were largely from industrial emissions transported out through the north. In the Tibet region, dust was predominant during both April and July. During September

  17. 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.

  18. 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.

  19. 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

  20. Insights into Submicron Aerosol Composition and Sources from the WINTER Aircraft Campaign Over the Eastern US.

    NASA Astrophysics Data System (ADS)

    Schroder, J. C.; Campuzano Jost, P.; Day, D. A.; Fibiger, D. L.; McDuffie, E. E.; Blake, N. J.; Hills, A. J.; Hornbrook, R. S.; Apel, E. C.; Weinheimer, A. J.; Campos, T. L.; Brown, S. S.; Jimenez, J. L.

    2015-12-01

    The WINTER aircraft campaign was a recent field experiment to probe the sources and evolution of gas pollutants and aerosols in Northeast US urban and industrial plumes during the winter. A highly customized Aerodyne aerosol mass spectrometer (AMS) was flown on the NCAR C-130 to characterize submicron aerosol composition and evolution. Thirteen research flights were conducted covering a wide range of conditions, including rural, urban, and marine environments during day and night. Organic aerosol (OA) was a large component of the submicron aerosol in the boundary layer. The fraction of OA (fOA) was smaller (35-40%) than in recent US summer campaigns (~60-70%). Biomass burning was observed to be an important source of OA in the boundary layer, which is consistent with recent wintertime studies that show a substantial contribution of residential wood burning to the OA loadings. OA oxygenation (O/C ratio) shows a broad distribution with a substantial fraction of smaller O/C ratios when compared to previous summertime campaigns. Since measurements were rarely made very close to primary sources (i.e. directly above urban areas), this is consistent with oxidative chemistry being slower during winter. SOA formation and aging in the NYC plume was observed during several flights and compared with summertime results from LA (CalNex) and Mexico City (MILAGRO). Additionally, an oxidation flow reactor (OFR) capable of oxidizing ambient air up to several equivalent days of oxidation was deployed for the first time in an aircraft platform. The aerosol outflow of the OFR was sampled with the AMS to provide real-time snapshots of the potential for aerosol formation and aging. For example, a case study of a flight through the Ohio River valley showed evidence of oxidation of SO2 to sulfate. The measured sulfate enhancements were in good agreement with our OFR chemical model. OFR results for SOA will be discussed.

  1. Size-dependent chemical ageing of oleic acid aerosol under dry and humidified conditions

    NASA Astrophysics Data System (ADS)

    Al-Kindi, Suad S.; Pope, Francis D.; Beddows, David C.; Bloss, William J.; Harrison, Roy M.

    2016-12-01

    A chemical reaction chamber system has been developed for the processing of oleic acid aerosol particles with ozone under two relative humidity conditions: dry and humidified to 65 %. The apparatus consists of an aerosol flow tube, in which the ozonolysis occurs, coupled to a scanning mobility particle sizer (SMPS) and an aerosol time-of-flight mass spectrometer (ATOFMS) which measure the evolving particle size and composition. Under both relative humidity conditions, ozonolysis results in a significant decrease in particle size and mass which is consistent with the formation of volatile products that partition from the particle to the gas phase. Mass spectra derived from the ATOFMS reveal the presence of the typically observed reaction products: azelaic acid, nonanal, oxononanoic acid and nonanoic acid, as well as a range of higher molecular weight products deriving from the reactions of reaction intermediates with oleic acid and its oxidation products. These include octanoic acid and 9- and 10-oxooctadecanoic acid, as well as products of considerably higher molecular weight. Quantitative evaluation of product yields with the ATOFMS shows a marked dependence upon both particle size association (from 0.3 to 2.1 µm diameter) and relative humidity. Under both relative humidity conditions, the percentage residual of oleic acid increases with increasing particle size and the main lower molecular weight products are nonanal and oxononanoic acid. Under dry conditions, the percentage of higher molecular weight products increases with increasing particle size due to the poorer internal mixing of the larger particles. Under humidified conditions, the percentage of unreacted oleic acid is greater, except in the smallest particle fraction, with little formation of high molecular weight products relative to the dry particles. It is postulated that water reacts with reactive intermediates, competing with the processes which produce high molecular weight products. Whilst the

  2. Aerosol chemical vapor deposition of metal oxide films

    DOEpatents

    Ott, Kevin C.; Kodas, Toivo T.

    1994-01-01

    A process of preparing a film of a multicomponent metal oxide including: forming an aerosol from a solution comprised of a suitable solvent and at least two precursor compounds capable of volatilizing at temperatures lower than the decomposition temperature of said precursor compounds; passing said aerosol in combination with a suitable oxygen-containing carrier gas into a heated zone, said heated zone having a temperature sufficient to evaporate the solvent and volatilize said precursor compounds; and passing said volatilized precursor compounds against the surface of a substrate, said substrate having a sufficient temperature to decompose said volatilized precursor compounds whereby metal atoms contained within said volatilized precursor compounds are deposited as a metal oxide film upon the substrate is disclosed. In addition, a coated article comprising a multicomponent metal oxide film conforming to the surface of a substrate selected from the group consisting of silicon, magnesium oxide, yttrium-stabilized zirconium oxide, sapphire, or lanthanum gallate, said multicomponent metal oxide film characterized as having a substantially uniform thickness upon said FIELD OF THE INVENTION The present invention relates to the field of film coating deposition techniques, and more particularly to the deposition of multicomponent metal oxide films by aerosol chemical vapor deposition. This invention is the result of a contract with the Department of Energy (Contract No. W-7405-ENG-36).

  3. 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.

  4. 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.

  5. Polycyclic Aromatic Aerosol Components: Chemical Analysis and Reactivity

    NASA Astrophysics Data System (ADS)

    Schauer, C.; Niessner, R.; Pöschl, U.

    Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants in the atmosphere and originate primarily from incomplete combustion of organic matter and fossil fuels. Their main sources are anthropogenic (e.g. vehicle emissions, domes- tic heating or tobacco smoke), and PAHs consisting of more than four fused aromatic rings reside mostly on combustion aerosol particles, where they can react with atmo- spheric trace gases like O3, NOx or OH radicals leading to a wide variety of partially oxidized and nitrated derivatives. Such chemical transformations can strongly affect the activity of the aerosol particles as condensation nuclei, their atmospheric residence times, and consequently their direct and indirect climatic effects. Moreover some poly- cyclic aromatic compounds (PACs = PAHs + derivatives) are known to have a high carcinogenic, mutagenic and allergenic potential, and are thus of major importance in air pollution control. Furthermore PACs can be used as well defined soot model sub- stances, since the basic structure of soot can be regarded as an agglomerate of highly polymerized PAC-layers. For the chemical analysis of polycyclic aromatic aerosol components a new analyti- cal method based on LC-APCI-MS has been developed, and a data base comprising PAHs, Oxy-PAHs and Nitro-PAHs has been established. Together with a GC-HRMS method it will be applied to identify and quantify PAHs and Nitro-PAHs in atmo- spheric aerosol samples, diesel exhaust particle samples and model soot samples from laboratory reaction kinetics and product studies. As reported before, the adsorption and surface reaction rate of ozone on soot and PAH-like particle surfaces is reduced by competitive adsorption of water vapor at low relative humidity (< 25 %). Recent results at higher relative humidities (ca. 50 %), however, indicate re-enhanced gas phase ozone loss, which may be due to absorbtion of ozone into an aqueous surface layer. The interaction of ozone and nitrogen

  6. Modeling regional secondary organic aerosol using the Master Chemical Mechanism

    NASA Astrophysics Data System (ADS)

    Li, Jingyi; Cleveland, Meredith; Ziemba, Luke D.; Griffin, Robert J.; Barsanti, Kelley C.; Pankow, James F.; Ying, Qi

    2015-02-01

    A modified near-explicit Master Chemical Mechanism (MCM, version 3.2) with 5727 species and 16,930 reactions and an equilibrium partitioning module was incorporated into the Community Air Quality Model (CMAQ) to predict the regional concentrations of secondary organic aerosol (SOA) from volatile organic compounds (VOCs) in the eastern United States (US). In addition to the semi-volatile SOA from equilibrium partitioning, reactive surface uptake processes were used to simulate SOA formation due to isoprene epoxydiol, glyoxal and methylglyoxal. The CMAQ-MCM-SOA model was applied to simulate SOA formation during a two-week episode from August 28 to September 7, 2006. The southeastern US has the highest SOA, with a maximum episode-averaged concentration of ∼12 μg m-3. Primary organic aerosol (POA) and SOA concentrations predicted by CMAQ-MCM-SOA agree well with AMS-derived hydrocarbon-like organic aerosol (HOA) and oxygenated organic aerosol (OOA) urban concentrations at the Moody Tower at the University of Houston. Predicted molecular properties of SOA (O/C, H/C, N/C and OM/OC ratios) at the site are similar to those reported in other urban areas, and O/C values agree with measured O/C at the same site. Isoprene epoxydiol is predicted to be the largest contributor to total SOA concentration in the southeast US, followed by methylglyoxal and glyoxal. The semi-volatile SOA components are dominated by products from β-caryophyllene oxidation, but the major species and their concentrations are sensitive to errors in saturation vapor pressure estimation. A uniform decrease of saturation vapor pressure by a factor of 100 for all condensable compounds can lead to a 150% increase in total SOA. A sensitivity simulation with UNIFAC-calculated activity coefficients (ignoring phase separation and water molecule partitioning into the organic phase) led to a 10% change in the predicted semi-volatile SOA concentrations.

  7. 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.

  8. 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.

  9. Characterizing the Asian Tropopause Aerosol Layer (ATAL) Using Satellite Observations, Balloon Measurements and a Chemical Transport Model

    NASA Technical Reports Server (NTRS)

    Fairlie, T. D.; Vernier, J.-P.; Liu, H.; Deshler, T.; Natarajan, M.; Bedka, K.; Wegner, T.; Baker, N.; Gadhavi, H.; Ratnam, M. V.; Jayaraman, A.; Pandit, A.; Raj, A.; Kumar, H.; Kumar, S.; Singh, A.; Stenchikov, G.; Wienhold, F.; Bian, J.

    2016-01-01

    Satellite observations and numerical modeling studies have demonstrated that the Asian Summer Monsoon (ASM) provide a conduit for gas-phase pollutants in south Asia to reach the lower stratosphere. Now, observations from the CALIPSO satellite have revealed the Asian Tropopause Aerosol Layer (ATAL), a summertime accumulation of aerosols in the upper troposphere and lower stratosphere (UTLS), associated with the ASM anticyclone. The ATAL has potential implications for regional cloud properties, climate, and chemical processes in the UTLS. Here, we show in situ measurements from balloon-borne instruments, aircraft, and satellite observations, together with trajectory and chemical transport model (CTM) simulations to explore the origin, composition, physical, and optical properties of aerosols in the ATAL. In particular, we show balloon-data from our BATAL-2015 field campaign to India and Saudi Arabia in summer 2015, which includes in situ backscatter measurements from COBALD instruments, and the first observations of size and volatility of aerosols in the ATAL layer using optical particle counters (OPCs). Back trajectory calculations initialized from CALIPSO observations point to deep convection over North India as a principal source of ATAL aerosols. Available aircraft observations suggest significant sulfur and carbonaceous components to the ATAL, which is supported by simulations using the GEOS-Chem CTM. Source elimination studies conducted with the GEOS-Chem indicate that ATAL aerosols originate primary from south Asian sources, in contrast with some earlier studies.

  10. Estimation of atmospheric aerosol composition from ground-based remote sensing measurements of Sun-sky radiometer

    NASA Astrophysics Data System (ADS)

    Xie, Y. S.; Li, Z. Q.; Zhang, Y. X.; Zhang, Y.; Li, D. H.; Li, K. T.; Xu, H.; Zhang, Y.; Wang, Y. Q.; Chen, X. F.; Schauer, J. J.; Bergin, M.

    2017-01-01

    Remote sensing provides aerosol loading information, but to address climate and air quality model validation, there are additional needs to acquire aerosol composition information. In this study, a comprehensive aerosol composition model is established to quantify black carbon (BC), brown carbon (BrC), mineral dust (DU), particulate organic matters, ammonium sulfate like (AS), sea salt, and aerosol water uptake. We develop forward modeling of aerosol components, including microphysical parameters (real and imaginary refractive indices, volume fraction ratio of fine to coarse mode, and sphericity) and hygroscopic growth models, and propose an optimization scheme to estimate the components. The uncertainties caused by input parameters are also assessed. Sun-sky radiometer measurements and meteorological data obtained during a campaign in Huairou, Beijing, are processed to estimate aerosol components, which are further compared with synchronous in situ chemical measurements. The results show generally good consistencies between remotely estimated and measured components (e.g., correlation coefficients for BC, BrC, AS, and PM2.5 lie in about 0.8-0.9). The comparisons between modeled and observed microphysical parameters also show good agreements, with the exception of sphericity, which is likely caused by high uncertainties of this parameter. Sensitivity studies show that BC and BrC are highly sensitive to imaginary refractive index, while DU is strongly correlated to both volume size and sphericity. The performance of composition retrieval is expected to be improved when the sphericity uncertainty is significantly reduced.

  11. Water-Soluble Organic Species in Biomass Burning Aerosols in Southern Africa: Their Chemical Identification and Spatial Distribution

    NASA Astrophysics Data System (ADS)

    Gao, S.; Hegg, D. A.; Hobbs, P. V.; Kirchstetter, T. W.; Magi, B.

    2001-12-01

    During the SAFARI-2000 field campaign, 14 aerosol samples were collected from an aircraft in plumes from biomass fires (under both flaming and smoldering conditions), at various distances from the fire source. Also collected were 36 aerosol samples in haze layers ranging from the surface to 16,000 feet, some of which could be associated with specific fires. The samples were collected on teflon membrane filters (lower size limit of about 30nm in diameter) which were analyzed for total aerosol mass loading and chemical composition using several analytical techniques. Particular effort was made to speciate the water-soluble portion of the aerosol organics. Seven organic acids and seven carbohydrate species (and their possible stereoisomers) were identified and quantified, along with three inorganic anions and five inorganic cations. The identified organic species accounted for up to 32% of the total aerosol mass; compared with concurrent total carbon and organic carbon measurements, the identified organics constituted at least 5% to 30% of the mass of the total aerosol organics. A number of conspicuous spatial distribution patterns were observed for these species. For instance, using K+ to correct for dilution, it was found that gluconate, oxalate, succinate, and glutarate, along with sulfate and nitrate, all increased significantly in mass concentration from the fire source going downwind. This suggests secondary formation of these species during aerosol aging. On the other hand, formate and acetate showed decreasing trends downwind, probably due to the loss of these volatile species to the gas phase. Another striking pattern is that anhydrosugars (e.g. levoglucosan) had the highest aerosol mass fraction near smoldering fires but a very low fraction in the haze layers, whereas, dicarboxylic acids showed an almost opposite trend. This implies possible chemical reaction processes converting intermediate organic products, such as levoglucosan, to smaller products like

  12. Intercomparison of an Aerosol Chemical Speciation Monitor (ACSM) with ambient fine aerosol measurements in Downtown Atlanta, Georgia

    NASA Astrophysics Data System (ADS)

    Budisulistiorini, S. H.; Canagaratna, M. R.; Croteau, P. L.; Baumann, K.; Edgerton, E. S.; Kollman, M. S.; Ng, N. L.; Verma, V.; Shaw, S. L.; Knipping, E. M.; Worsnop, D. R.; Jayne, J. T.; Weber, R. J.; Surratt, J. D.

    2013-12-01

    The Aerodyne Aerosol Chemical Speciation Monitor (ACSM) was recently developed to provide long-term real-time continuous measurements of ambient non-refractory (i.e., organic, sulfate, ammonium, nitrate, and chloride) submicron particulate matter (NR-PM1). Currently, there are a limited number of field studies that evaluate the long-term performance of the ACSM against established monitoring networks. In this study, we present seasonal intercomparisons of the ACSM with collocated fine aerosol (PM2.5) measurements at the Southeastern Aerosol Research and Characterization (SEARCH) Jefferson Street (JST) site near downtown Atlanta, GA, during 2011-2012. The collocated measurements included a second ACSM, continuous and integrated sulfate, nitrate, and ammonium measurements, as well as a semi-continuous Sunset organic carbon/elemental carbon (OC/EC) analyzer, continuous tapered element oscillating microbalance (TEOM), 24 h integrated Federal Reference Method (FRM) filters, and continuous scanning electrical mobility system-mixing condensation particle counter (SEMS-MCPC). Intercomparison of the two collocated ACSMs resulted in strong correlations (r2 > 0.8) for all chemical species, except chloride (r2 = 0.21); mass concentration for all chemical species agreed within ±27%, indicating that ACSM instruments are capable of stable and reproducible operation. Chemical constituents measured by the ACSM are also compared with those obtained from the continuous measurements from JST. Since the continuous measurement concentrations are adjusted to match the integrated filter measurements, these comparisons reflect the combined uncertainties of the ACSM, continuous, and filter measurements. In general, speciated ACSM mass concentrations correlate well (r2 > 0.7) with the continuous measurements from JST, although the correlation for nitrate is weaker (r2 = 0.55) in summer. Differences between ACSM mass concentrations and the filter-adjusted JST continuous data are 5-27%, 4

  13. 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

  14. Chemical, Physical and Optical Properties of Saharan Dust Aerosols at a Marine Site in Puerto Rico

    NASA Astrophysics Data System (ADS)

    Ortiz Montalvo, D. L.; Mayol Bracero, O. L.; Morales, F.; Sheridan, P.; Ogren, J. A.

    2005-12-01

    Atmospheric dust particles blown from the Sahara across the Atlantic into the Caribbean have an impact on its climate and public health. These particles may play a significant role in radiative forcing, affecting the extinction of solar radiation and thus having an influence on climate. About half of the dust that travels from Africa contains particles that are small enough to inhale. Human breathe them into the respiratory system and they settle in the lungs causing respiratory problems. To have a better understanding of these effects, information is needed on the properties of these aerosols. As part of this study, chemical, physical and optical characterization is being performed on aerosol samples collected at a marine site on the northeastern tip of Puerto Rico (Cabezas de San Juan, Fajardo), during periods with and without Saharan incursions. Stacked-filter units (SFU) are used to collect particles with diameters smaller than 1.7 μm, using Nuclepore, quartz and Teflon filters. These filter samples are analyzed to obtain the chemical composition of the particles. Initially we are focusing on the carbonaceous fraction (elemental and organic carbon, EC, and OC) of the aerosol using thermal/optical analysis. Online measurements of total particle number concentrations and aerosol light scattering coefficients are performed using a condensation particle counter and an integrating nephelometer, respectively. In addition, a sunphotometer, part of AERONET (http://aeronet.gsfc.nasa.gov/), is used to obtain the aerosol optical thickness (AOT). Preliminary results include only samples collected from air masses under the influence of Saharan dust, as signified by AOT satellite images from MODIS and the results from the air masses backward trajectories calculated with the NOAA HYSPLIT (HYbrid Single-Particle Lagrangian Integrated Trajectory) model. In terms of the chemical composition, EC concentrations were at low-to-undetectable levels, indicating that OC concentrations

  15. 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

  16. Inorganic Salt Interference on CO2(+) in Aerodyne AMS and ACSM Organic Aerosol Composition Studies.

    PubMed

    Pieber, Simone M; El Haddad, Imad; Slowik, Jay G; Canagaratna, Manjula R; Jayne, John T; Platt, Stephen M; Bozzetti, Carlo; Daellenbach, Kaspar R; Fröhlich, Roman; Vlachou, Athanasia; Klein, Felix; Dommen, Josef; Miljevic, Branka; Jiménez, José L; Worsnop, Douglas R; Baltensperger, Urs; Prévôt, André S H

    2016-10-04

    Aerodyne aerosol mass spectrometer (AMS) and Aerodyne aerosol chemical speciation monitor (ACSM) mass spectra are widely used to quantify organic aerosol (OA) elemental composition, oxidation state, and major environmental sources. The OA CO2(+) fragment is among the most important measurements for such analyses. Here, we show that a non-OA CO2(+) signal can arise from reactions on the particle vaporizer, ion chamber, or both, induced by thermal decomposition products of inorganic salts. In our tests (eight instruments, n = 29), ammonium nitrate (NH4NO3) causes a median CO2(+) interference signal of +3.4% relative to nitrate. This interference is highly variable between instruments and with measurement history (percentiles P10-90 = +0.4 to +10.2%). Other semi-refractory nitrate salts showed 2-10 times enhanced interference compared to that of NH4NO3, while the ammonium sulfate ((NH4)2SO4) induced interference was 3-10 times lower. Propagation of the CO2(+) interference to other ions during standard AMS and ACSM data analysis affects the calculated OA mass, mass spectra, molecular oxygen-to-carbon ratio (O/C), and f44. The resulting bias may be trivial for most ambient data sets but can be significant for aerosol with higher inorganic fractions (>50%), e.g., for low ambient temperatures, or laboratory experiments. The large variation between instruments makes it imperative to regularly quantify this effect on individual AMS and ACSM systems.

  17. The Time Evolution of Aerosol Composition Over the Mexico City Plateau

    SciTech Connect

    Kleinman, Lawrence I.; Springston, Stephen R.; Daum, Peter H.; Lee, Y. - N.; Nunnermacker, L. J.; Senum, Gunar; Wang, J. X.; Weinstein-Lloyd, Judy; Alexander, M. L.; Hubbe, John M.; Ortega, John V.; Canagaratna, M. R.; Jayne, John

    2008-03-17

    The time evolution of aerosol concentration and chemical composition in a megacity urban plume was determined based on 8 flights of the DOE G-1 aircraft in and downwind of Mexico City during the March 2006 MILAGRO field campaign. A series of selection criteria are imposed to eliminate data points with non-urban emission influences. Biomass burning has urban and non-urban sources that are distinguished on the basis of CH3CN and CO. In order to account for dilution in the urban plume, aerosol concentrations are normalized to CO which is taken as an inert tracer of urban emission, proportional to the emissions of aerosol precursors. Time evolution is determined with respect to photochemical age defined as -Log10 (NOx/NOy). The geographic distribution of photochemical age and CO is examined, confirming the picture that Mexico City is a source region and that pollutants become more dilute and aged as they are advected towards T1 and T2, surface sites that are located at the fringe of the City and 35 km to the NE, respectively. Organic aerosol (OA) per ppm CO is found to increase 7 fold over the range of photochemical ages studied, corresponding to a change in NOx/NOy from nearly 100% to 10%.

  18. SPACCIM simulations of chemical aerosol-cloud interactions with the multiphase chemistry mechanism MCM-CAPRAM3.0

    NASA Astrophysics Data System (ADS)

    Tilgner, A.; Schroedner, R.; Braeuer, P.; Wolke, R.; Herrmann, H.

    2010-12-01

    A wide variety of organic compounds is emitted into the troposphere and is then oxidised by complex multiphase degradations leading to secondary organics which partition between the tropospheric gas and aqueous phase, i.e. deliquescent particles and cloud droplets. Secondary organics play a key role in tropospheric chemistry and account for a substantial fraction of tropospheric aerosol mass. Heterogeneous and multiphase processes in fog droplets, cloud droplets and deliquescent particles can potentially alter the physico-chemical composition of the tropospheric aerosol on global scale. However, the chemical multiphase processing, i.e. secondary formation and aging mainly of organic aerosols remains poorly considered in current multiphase chemical mechanisms and models. In order to model such complex tropospheric multiphase chemical interactions of clouds, fogs and deliquescent aerosol particles, chemical mechanisms with a detailed description of chemical processes in both the gas and aqueous phase are required. Currently, both near-explicit gas and aqueous phase mechanisms are available. However, a near-explicit chemical multiphase mechanism was still missing. Therefore, the near-explicit chemical gas phase mechanism MCM v3 (Master Chemical Mechanism) with about 13502 reactions and the explicit aqueous phase mechanism CAPRAM3.0n (Chemical Aqueous Phase Radical Mechanism) with about 777 reactions were coupled and integrated into the model framework SPACCIM (SPectral Aerosol Cloud Chemistry Interaction Model). The parcel model SPACCIM combines a complex microphysical and multiphase chemistry model. First SPACCIM simulations have been carried out for different environmental conditions using a non-permanent cloud scenario. The model studies were aimed to investigate multiphase chemistry in tropospheric deliquescent aerosol particles, fogs and clouds in more detail. The present model studies were focused on multiphase chemistry of tropospheric oxidants and closely

  19. 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.

  20. Aerosol composition, sources and processes during wintertime in Beijing, China

    NASA Astrophysics Data System (ADS)

    Sun, Y. L.; Wang, Z. F.; Fu, P. Q.; Yang, T.; Jiang, Q.; Dong, H. B.; Li, J.; Jia, J. J.

    2013-05-01

    Air pollution is a major environmental concern during all seasons in the megacity of Beijing, China. Here we present the results from a winter study that was conducted from 21 November 2011 to 20 January 2012 with an Aerodyne Aerosol Chemical Speciation Monitor (ACSM) and various collocated instruments. The non-refractory submicron aerosol (NR-PM1) species vary dramatically with clean periods and pollution episodes alternating frequently. Compared to summer, wintertime submicron aerosols show much enhanced organics and chloride, which on average account for 52% and 5%, respectively, of the total NR-PM1 mass. All NR-PM1 species show quite different diurnal behaviors between summer and winter. For example, the wintertime nitrate presents a gradual increase during daytime and correlates well with secondary organic aerosol (OA), indicating a dominant role of photochemical production over gas-particle partitioning. Positive matrix factorization was performed on ACSM OA mass spectra, and identified three primary OA (POA) factors, i.e., hydrocarbon-like OA (HOA), cooking OA (COA), and coal combustion OA (CCOA), and one secondary factor, i.e., oxygenated OA (OOA). The POA dominates OA during wintertime, contributing 69%, with the other 31% being SOA. Further, all POA components show pronounced diurnal cycles with the highest concentrations occurring at nighttime. CCOA is the largest primary source during the heating season, on average accounting for 33% of OA and 17% of NR-PM1. CCOA also plays a significant role in chemically resolved particulate matter (PM) pollution as its mass contribution increases linearly as a function of NR-PM1 mass loadings. The SOA, however, presents a reverse trend, which might indicate the limited SOA formation during high PM pollution episodes in winter. The effects of meteorology on PM pollution and aerosol processing were also explored. In particular, the sulfate mass is largely enhanced during periods with high humidity because of fog

  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. Elucidating the Chemical Complexity of Organic Aerosol Constituents Measured During the Southeastern Oxidant and Aerosol Study (SOAS)

    NASA Astrophysics Data System (ADS)

    Yee, L.; Isaacman, G. A.; Spielman, S. R.; Worton, D. R.; Zhang, H.; Kreisberg, N. M.; Wilson, K. R.; Hering, S. V.; Goldstein, A. H.

    2013-12-01

    Thousands of volatile organic compounds are uniquely created in the atmosphere, many of which undergo chemical transformations that result in more highly-oxidized and often lower vapor pressure species. These species can contribute to secondary organic aerosol, a complex mixture of organic compounds that is still not chemically well-resolved. Organic aerosol collected on filters taken during the Southeastern Oxidant and Aerosol Study (SOAS) constitute hundreds of unique chemical compounds. Some of these include known anthropogenic and biogenic tracers characterized using standardized analytical techniques (e.g. GC-MS, UPLC, LC-MS), but the majority of the chemical diversity has yet to be explored. By employing analytical techniques involving sample derivatization and comprehensive two-dimensional gas chromatography (GC x GC) with high-resolution-time-of-flight mass spectrometry (HR-ToF-MS), we elucidate the chemical complexity of the organic aerosol matrix along the volatility and polarity grids. Further, by utilizing both electron impact (EI) and novel soft vacuum ultraviolet (VUV) ionization mass spectrometry, a greater fraction of the organic mass is fully speciated. The GC x GC-HR-ToF-MS with EI/VUV technique efficiently provides an unprecedented level of speciation for complex ambient samples. We present an extensive chemical characterization and quantification of organic species that goes beyond typical atmospheric tracers in the SOAS samples. We further demonstrate that complex organic mixtures can be chemically deconvoluted by elucidation of chemical formulae, volatility, functionality, and polarity. These parameters provide insight into the sources (anthropogenic vs. biogenic), chemical processes (oxidation pathways), and environmental factors (temperature, humidity), controlling organic aerosol growth in the Southeastern United States.

  3. COBRA: A Computational Brewing Application for Predicting the Molecular Composition of Organic Aerosols

    SciTech Connect

    Fooshee, David R.; Nguyen, Tran B.; Nizkorodov, Sergey A.; Laskin, Julia; Laskin, Alexander; Baldi, Pierre

    2012-05-08

    Atmospheric organic aerosols (OA) represent a significant fraction of airborne particulate matter and can impact climate, visibility, and human health. These mixtures are difficult to characterize experimentally due to the enormous complexity and dynamic nature of their chemical composition. We introduce a novel Computational Brewing Application (COBRA) and apply it to modeling oligomerization chemistry stemming from condensation and addition reactions of monomers pertinent to secondary organic aerosol (SOA) formed by photooxidation of isoprene. COBRA uses two lists as input: a list of chemical structures comprising the molecular starting pool, and a list of rules defining potential reactions between molecules. Reactions are performed iteratively, with products of all previous iterations serving as reactants for the next one. The simulation generated thousands of molecular structures in the mass range of 120-500 Da, and correctly predicted ~70% of the individual SOA constituents observed by high-resolution mass spectrometry (HR-MS). Selected predicted structures were confirmed with tandem mass spectrometry. Esterification and hemiacetal formation reactions were shown to play the most significant role in oligomer formation, whereas aldol condensation was shown to be insignificant. COBRA is not limited to atmospheric aerosol chemistry, but is broadly applicable to the prediction of reaction products in other complex mixtures for which reasonable reaction mechanisms and seed molecules can be supplied by experimental or theoretical methods.

  4. 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

  5. The Microphysical and Chemical properties of aerosol particles from the United Arab Emirates Unified Aerosol Experiment (UAE2) and from the Bodele-BODEX Experiment

    NASA Astrophysics Data System (ADS)

    Martins, J.; Chaudhry, Z.; Todd, M.; Kaufman, Y.; Artaxo, P.

    2005-12-01

    Aerosol filters collected during the UAE2 experiment (August 2004), and during the BODEX experiment (in the Bodele region, February 2005) were analyzed for spectral absorption properties (from 350-2500nm), mass concentration (fine and coarse modes), electron microscopy, and chemical composition. The UAE2 samples show evidence of absorption by dust and urban pollution particles. In the fine mode, the urban pollution particles show spectral dependence inversely proportional to the wavelength, which is compatible with small black carbon aerosols. The coarse mode shows evidences of the internal mixture between dust and pollution, producing the typical strong absorption in UV-Visible wavelengths produced by dust, as well as significant absorption in the NIR (near infrared) coming from the dust-pollution combination. On the other hand, the Bodele samples show at least two types of dust absorption behavior: 1 - very strong absorption efficiency in the UV and visible wavelengths with nearly no absorption in the NIR; 2 - very strong absorption efficiency in the UV-VIS region with significant absorption in the NIR. Additional samples collected in the Amazon region, in Brazil, show evidence of long-range transport of dust from the Sahara. The chemical composition and microphysical properties of the Amazon Samples are compared with those measured in the UAE and Bodele regions. The chemical composition of these samples provides additional insight on previous theories of the fertilization of the Amazon by long-range transport of dust from the Sahara region.

  6. Chemical Characterization and Toxicologic Evaluation of Airborne Mixtures: The Chemical and Physical Characterization of XM819 Red Phosphorus Formulation and the Aerosol Produced by Its Combustion

    DTIC Science & Technology

    1986-02-01

    Composite Infrared Spectre of XR-819 Wedge Plus . Unhardened Epon 828 ........ . ..... . . . 17 S Static 5urn Chamber . ................ 20 6 Aerosol... reflectance fourier transform Infrared spectra were recorded on a Digileb FTS-20C spectromete;. A sample of Epon 828 was received from Shell Chemical...are metal, glass and teflon to minimize artifactual contami- nation of the smoke products. The container has openings whereby air flow is regulated

  7. 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

  8. Determining the chemical composition of cloud condensation nuclei

    SciTech Connect

    Williams, A.L.; Rothert, J.E.; McClure, K.E. ); Alofs, D.J.; Hagen, D.E.; White, D.R.; Hopkins, A.R.; Trueblood, M.B. . Cloud and Aerosol Science Lab.)

    1992-02-01

    This second progress report describes the status of the project one and one-half years after the start. The goal of the project is to develop the instrumentation to collect cloud condensation nuclei (CCN) in sufficient amounts to determine their chemical composition, and to survey the CCN composition in different climates through a series of field measurements. Our approach to CCN collection is to first form droplets on the nuclei under simulated cloud humidity conditions, which is the only known method of identifying CCN from the background aerosol. Under cloud chamber conditions, the droplets formed become larger than the surrounding aerosol, and can then be removed by inertial impaction. The residue of the evaporated droplets represents the sample to be chemically analyzed. Two size functions of CCN particles are collected by first forming droplets on the large particles are collected by first forming droplets on the large CCN in a haze chamber at 100% relative humidity, and then activating the remaining CCN at 1% supersaturation in a cloud chamber. The experimental apparatus is a serious flow arrangement consisting of an impactor to remove the large aerosol particles, a haze chamber to form droplets on the remaining larger CCN, another impactor to remove the haze droplets containing the larger CCN particles for chemical analysis, a continuous flow diffusion (CFD) cloud chamber to form droplets on the remaining smaller CCN, and a third impactor to remove the droplets for the small CCN sample. Progress is documented here on the development of each of the major components of the flow system. Chemical results are reported on tests to determine suitable wicking material for the different plates. Results of computer modeling of various impactor flows are discussed.

  9. Aerosol Composition in the Los Angeles Basin Studied by High Resolution Aerosol Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Hayes, P. L.; Ortega, A. M.; Cubison, M.; Hu, W.; Toohey, D. W.; Flynn, J. H.; Grossberg, N.; Lefer, B. L.; Alvarez, S. L.; Rappenglueck, B.; Allan, J. D.; Taylor, J.; Holloway, J. S.; Gilman, J. B.; Kuster, W. C.; De Gouw, J. A.; Massoli, P.; Zhang, X.; Weber, R.; Zhao, Y.; Cliff, S. S.; Wexler, A. S.; Isaacman, G. A.; Worton, D. R.; Kreisberg, N. M.; Hering, S. V.; Goldstein, A. H.; Jimenez, J. L.

    2011-12-01

    Atmospheric aerosols impact climate and health, but their sources and composition are poorly understood. To address this knowledge gap, a high-resolution aerosol mass spectrometer (AMS) and complementary instrumentation were deployed during the 2010 CalNex campaign to characterize aerosol composition in the Los Angeles (LA) area. Total mass concentrations as well as the species concentrations measured by the AMS compare well with most other instruments. Nitrate dominates in the mornings, but its concentration is reduced in the afternoon when organic aerosols (OA) increase and dominate. The diurnal variations in concentrations are strongly influenced by emission transport from the source-rich western basin. The average OA to enhanced CO ratio increases with photochemical age from 25 to 80 μg m-3 ppm-1, which indicates significant secondary OA (SOA) production and that a large majority of OA is secondary in aged air. The ratio values are similar to those from Mexico City as well as New England and the Mid-Atlantic States. Positive matrix factorization (PMF) is used to assess the concentrations of different OA components. The major OA classes are oxygenated OA (OOA, a surrogate for total SOA), and hydrocarbon-like OA (HOA, a surrogate for primary combustion OA). Several subclasses of OA are identified as well including diesel-influenced HOA (DI-HOA) and non-diesel HOA. DI-HOA exhibits low concentrations on Sundays consistent with the well-known weekday/weekend effect in LA. PMF analysis finds that OOA is 67% of the total OA concentration. A strong correlation between OOA and Ox (O3 + NO2) concentrations is observed with a slope of 0.15 that suggests the production of fresh SOA in Pasadena. Plotting the OA elemental ratios in a Van Krevelen diagram (H:C vs. O:C) yields a slope of -0.6, which is less steep than that observed in Riverside during the SOAR-2005 campaign. The difference in slopes may be attributed to the highly oxidized HOA present in Pasadena that is

  10. 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

    concentrations using a Licor LI-7000 and dew point (Buck Research Instruments model CR-1A). A suite of experiments was conducted in which the; (i) Aerosol particle composition was varied (4 chemical compounds) (ii) Aerosol particle GMD was varied (40-80 nm) (iii) Aerosol particle total number concentration was varied (2 orders of magnitude) (iv) Tree type was varied (using a range of species and alternately lacquering the trees to prevent active uptake) (v) Light, water vapor content and CO2 concentrations inside the chamber were varied in order to mimic the range of conditions observed at our experimental particle flux site in southern Indiana (see related abstract by Pryor and Hornsby that describes the in situ flux estimates). The results of these laboratory experiments are used to quantify the relative importance of these factors in dictating aerosol particle uptake and specifically the importance of the foliage collection mechanisms at the leaf scale and deposition flux partitioning between foliage and non-foliage elements.

  11. 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.

  12. Measurement of Organic and Inorganic Chemical Tracers for Source Apportionment of Tropospheric Aerosols Collected During the ACE-Asia Experiment

    NASA Astrophysics Data System (ADS)

    Schauer, J. J.; Park, J.; Duvall, R.; Bae, M.; Shafer, M. M.; Chuang, P.; Chuang, P.; Kim, Y. J.

    2001-12-01

    Naturally occurring dust and anthropogenic air pollutants are important contributors to tropospheric aerosols and impact air quality and the radiative balance of the Earth's atmosphere. In order to better understand the relationship between the origin, chemical composition and ultimate impact of Asian aerosols on climate forcing, aerosol samples were collected as part of the ACE-Asia experiment for detailed chemical analysis. Atmospheric particulate matter samples were collected from March 27, 2001 through May 6, 2001 at the ACE-Asia ground station located on Cheju Island, Korea. During this period, this region is impacted by anthropogenic air pollution emissions from highly urbanized region of Asia and by desert dust originating from northeastern Asia. As part of the experiment, atmospheric particulate matter samplers were also collected in urban and desert locations in Asia that represent regional sources of particulate matter in Asia. Size resolved aerosol samples were analyzed for trace metals by using microwave assisted-acid digestion and ICP-MS analysis, speciated organic compounds using solvent extraction and GC-MS analysis, as well as soluble ions and elemental and organic carbon (ECOC). These measurements provide fingerprints for source apportionment of the atmospheric particulate matter samples collected at the Cheju Island sampling site. The use of these chemical tracers for apportionment of wind-driven long range transported desert dust, local crustal derived dust, biogenically and anthropogenically derived sulfate, specific urban combustion source, and fossil fuel combustion will be presented.

  13. 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.

  14. X-ray methods for the chemical characterization of atmospheric aerosols

    SciTech Connect

    Jaklevic, J.M.; Thompson, A.C.

    1981-05-01

    The development and use of several x-ray methods for the chemical characterization of atmospherical aerosol particulate samples are described. These methods are based on the emission, absorption, and scattering of x-ray photons with emphasis on the optimization for the non-destructive analysis of dilute specimens. Techniques discussed include photon induced energy dispersive x-ray fluorescence, extended x-ray absorption fine structure spectroscopy using synchrotron radiation and high-rate x-ray powder diffractometry using a position-sensitive gas proportional counter. These x-ray analysis methods were applied to the measurement of the chemical compositions of size-segregated aerosol particulate samples obtained with dichotomous samplers. The advantages of the various methods for use in such measurements are described and results are presented. In many cases, the complementary nature of the analytical information obtained from the various measurements is an important factor in the characterization of the sample. For example, the multiple elemental analyses obtained from x-ray fluorescence can be used as a cross check on the major compounds observed by powder diffraction.

  15. Relating hygroscopicity and composition of organic aerosol particulate matter

    SciTech Connect

    Duplissy, J.; DeCarlo, P. F.; Dommen, J.; Alfarra, M. R.; Metzger, A.; Barmpadimos, I.; Prevot, A. S. H.; Weingartner, E.; Tritscher, T.; Gysel, M.; Aiken, A. C.; Jimenez, J. L.; Canagaratna, M. R.; Worsnop, D. R.; Collins, D. R.; Tomlinson, J.; Baltensperger, U.

    2011-01-01

    A hygroscopicity tandem differential mobility analyzer (HTDMA) was used to measure the water uptake (hygroscopicity) of secondary organic aerosol (SOA) formed during the chemical and photochemical oxidation of several organic precursors in a smog chamber. Electron ionization mass spectra of the non-refractory submicron aerosol were simultaneously determined with an aerosol mass spectrometer (AMS), and correlations between the two different signals were investigated. SOA hygroscopicity was found to strongly correlate with the relative abundance of the ion signal m/z 44 expressed as a fraction of total organic signal (f44). m/z 44 is due mostly to the ion fragment CO2+ for all types of SOA systems studied, and has been previously shown to strongly correlate with organic O/C for ambient and chamber OA. The analysis was also performed on ambient OA from two field experiments at the remote site Jungfraujoch, and the megacity Mexico City, where similar results were found. A simple empirical linear relation between the hygroscopicity of OA at subsaturated RH, as given by the hygroscopic growth factor (GF) or "κorg" parameter, and f44 was determined and is given by κorg = 2.2 × f44 - 0.13. This approximation can be further verified and refined as the database for AMS and HTDMA measurements is constantly being expanded around the world. Finally, the use of this approximation could introduce an important simplification in the parameterization of hygroscopicity of OA in atmospheric models, since f44 is correlated with the photochemical age of an air mass.

  16. Chemical Characterization of Secondary Organic Aerosol Formed from Atmospheric Aqueous-phase Reactions of Phenolic Compounds

    NASA Astrophysics Data System (ADS)

    Yu, L.; Smith, J.; Anastasio, C.; Zhang, Q.

    2012-12-01

    Phenolic compounds, which are released in significant amounts from biomass burning, may undergo fast aqueous-phase reactions to form secondary organic aerosol (SOA) in the atmosphere. Understanding the aqueous-phase reaction mechanisms of these compounds and the composition of their reaction products is thus important for constraining SOA sources and predicting organic aerosol properties in models. In this study, we investigate the aqueous-phase reactions of three phenols (phenol, guaiacol and syringol) with two oxidants - excited triplet states (3C*) of non-phenolic aromatic carbonyls and hydroxyl radical (OH). By employing four analytical methods including high-resolution aerosol mass spectrometry, total organic carbon analysis, ion chromatography, and liquid chromatography-mass spectrometry, we thoroughly characterize the chemical compositions of the low volatility reaction products of phenols and propose formation mechanisms based on this information. Our results indicate that phenolic SOA is highly oxygenated, with O/C ratios in the range of 0.83-1.03, and that the SOA of phenol is usually more oxidized than those of guaiacol and syringol. Among the three precursors, syringol generates the largest fraction of higher molecular weight (MW) products. For the same precursor, the SOA formed via reaction with 3C* is less oxidized than that formed via reaction with OH. In addition, oxidation by 3C* enhances the formation of higher MW species, including phenolic dimers, higher oligomers and hydroxylated products, compared to reactions initiated by OH, which appear to favor the formation of organic acids. However, our results indicate that the yields of small organic acids (e.g., formate, acetate, oxalate, and malate) are low for both reaction pathways, together accounting for less than 5% of total SOA mass.

  17. On the competition among aerosol number, size and composition in predicting CCN variability: a multi-annual field study in an urbanized desert

    NASA Astrophysics Data System (ADS)

    Crosbie, E.; Youn, J.-S.; Balch, B.; Wonaschütz, A.; Shingler, T.; Wang, Z.; Conant, W. C.; Betterton, E. A.; Sorooshian, A.

    2015-06-01

    A 2-year data set of measured CCN (cloud condensation nuclei) concentrations at 0.2 % supersaturation is combined with aerosol size distribution and aerosol composition data to probe the effects of aerosol number concentrations, size distribution and composition on CCN patterns. Data were collected over a period of 2 years (2012-2014) in central Tucson, Arizona: a significant urban area surrounded by a sparsely populated desert. Average CCN concentrations are typically lowest in spring (233 cm-3), highest in winter (430 cm-3) and have a secondary peak during the North American monsoon season (July to September; 372 cm-3). There is significant variability outside of seasonal patterns, with extreme concentrations (1 and 99 % levels) ranging from 56 to 1945 cm-3 as measured during the winter, the season with highest variability. Modeled CCN concentrations based on fixed chemical composition achieve better closure in winter, with size and number alone able to predict 82 % of the variance in CCN concentration. Changes in aerosol chemical composition are typically aligned with changes in size and aerosol number, such that hygroscopicity can be parameterized even though it is still variable. In summer, models based on fixed chemical composition explain at best only 41 % (pre-monsoon) and 36 % (monsoon) of the variance. This is attributed to the effects of secondary organic aerosol (SOA) production, the competition between new particle formation and condensational growth, the complex interaction of meteorology, regional and local emissions and multi-phase chemistry during the North American monsoon. Chemical composition is found to be an important factor for improving predictability in spring and on longer timescales in winter. Parameterized models typically exhibit improved predictive skill when there are strong relationships between CCN concentrations and the prevailing meteorology and dominant aerosol physicochemical processes, suggesting that similar findings could be

  18. On the competition among aerosol number, size and composition in predicting CCN variability: a multi-annual field study in an urbanized desert

    PubMed Central

    Crosbie, E.; Youn, J.-S.; Balch, B.; Wonaschütz, A.; Shingler, T.; Wang, Z.; Conant, W. C.; Betterton, E. A.; Sorooshian, A.

    2015-01-01

    A 2-year data set of measured CCN (cloud condensation nuclei) concentrations at 0.2 % supersaturation is combined with aerosol size distribution and aerosol composition data to probe the effects of aerosol number concentrations, size distribution and composition on CCN patterns. Data were collected over a period of 2 years (2012–2014) in central Tucson, Arizona: a significant urban area surrounded by a sparsely populated desert. Average CCN concentrations are typically lowest in spring (233 cm−3), highest in winter (430 cm−3) and have a secondary peak during the North American monsoon season (July to September; 372 cm−3). There is significant variability outside of seasonal patterns, with extreme concentrations (1 and 99 % levels) ranging from 56 to 1945 cm−3 as measured during the winter, the season with highest variability. Modeled CCN concentrations based on fixed chemical composition achieve better closure in winter, with size and number alone able to predict 82% of the variance in CCN concentration. Changes in aerosol chemical composition are typically aligned with changes in size and aerosol number, such that hygroscopicity can be parameterized even though it is still variable. In summer, models based on fixed chemical composition explain at best only 41% (pre-monsoon) and 36% (monsoon) of the variance. This is attributed to the effects of secondary organic aerosol (SOA) production, the competition between new particle formation and condensational growth, the complex interaction of meteorology, regional and local emissions and multi-phase chemistry during the North American monsoon. Chemical composition is found to be an important factor for improving predictability in spring and on longer timescales in winter. Parameterized models typically exhibit improved predictive skill when there are strong relationships between CCN concentrations and the prevailing meteorology and dominant aerosol physicochemical processes, suggesting that similar findings

  19. On the competition among aerosol number, size and composition in predicting CCN variability: a multi-annual field study in an urbanized desert.

    PubMed

    Crosbie, E; Youn, J-S; Balch, B; Wonaschütz, A; Shingler, T; Wang, Z; Conant, W C; Betterton, E A; Sorooshian, A

    2015-02-10

    A 2-year data set of measured CCN (cloud condensation nuclei) concentrations at 0.2 % supersaturation is combined with aerosol size distribution and aerosol composition data to probe the effects of aerosol number concentrations, size distribution and composition on CCN patterns. Data were collected over a period of 2 years (2012-2014) in central Tucson, Arizona: a significant urban area surrounded by a sparsely populated desert. Average CCN concentrations are typically lowest in spring (233 cm(-3)), highest in winter (430 cm(-3)) and have a secondary peak during the North American monsoon season (July to September; 372 cm(-3)). There is significant variability outside of seasonal patterns, with extreme concentrations (1 and 99 % levels) ranging from 56 to 1945 cm(-3) as measured during the winter, the season with highest variability. Modeled CCN concentrations based on fixed chemical composition achieve better closure in winter, with size and number alone able to predict 82% of the variance in CCN concentration. Changes in aerosol chemical composition are typically aligned with changes in size and aerosol number, such that hygroscopicity can be parameterized even though it is still variable. In summer, models based on fixed chemical composition explain at best only 41% (pre-monsoon) and 36% (monsoon) of the variance. This is attributed to the effects of secondary organic aerosol (SOA) production, the competition between new particle formation and condensational growth, the complex interaction of meteorology, regional and local emissions and multi-phase chemistry during the North American monsoon. Chemical composition is found to be an important factor for improving predictability in spring and on longer timescales in winter. Parameterized models typically exhibit improved predictive skill when there are strong relationships between CCN concentrations and the prevailing meteorology and dominant aerosol physicochemical processes, suggesting that similar findings

  20. Chemical compositions of sulfate and chloride salts over the last termination reconstructed from the Dome Fuji ice core, inland Antarctica

    NASA Astrophysics Data System (ADS)

    Oyabu, Ikumi; Iizuka, Yoshinori; Uemura, Ryu; Miyake, Takayuki; Hirabayashi, Motohiro; Motoyama, Hideaki; Sakurai, Toshimitsu; Suzuki, Toshitaka; Hondoh, Takeo

    2014-12-01

    The flux and chemical composition of aerosols impact the climate. Antarctic ice cores preserve the record of past atmospheric aerosols, providing useful information about past atmospheric environments. However, few studies have directly measured the chemical composition of aerosol particles preserved in ice cores. Here we present the chemical compositions of sulfate and chloride salts from aerosol particles in the Dome Fuji ice core. The analysis method involves ice sublimation, and the period covers the last termination, 25.0-11.0 thousand years before present (kyr B.P.), with a 350 year resolution. The major components of the soluble particles are CaSO4, Na2SO4, and NaCl. The dominant sulfate salt changes at 16.8 kyr B.P. from CaSO4, a glacial type, to Na2SO4, an interglacial type. The sulfate salt flux (CaSO4 plus Na2SO4) inversely correlates with δ18O in Dome Fuji over millennial timescales. This correlation is consistent with the idea that sulfate salt aerosols contributed to the last deglacial warming of inland Antarctica by reducing the aerosol indirect effect. Between 16.3 and 11.0 kyr B.P., the presence of NaCl suggests that winter atmospheric aerosols are preserved. A high NaCl/Na2SO4 fraction between 12.3 and 11.0 kyr B.P. indicates that the contribution from the transport of winter atmospheric aerosols increased during this period.

  1. Composition, size and cloud condensation nuclei activity of biomass burning aerosol from northern Australian savannah fires

    NASA Astrophysics Data System (ADS)

    Mallet, Marc D.; Cravigan, Luke T.; Milic, Andelija; Alroe, Joel; Ristovski, Zoran D.; Ward, Jason; Keywood, Melita; Williams, Leah R.; Selleck, Paul; Miljevic, Branka

    2017-03-01

    The vast majority of Australia's fires occur in the tropical north of the continent during the dry season. These fires are a significant source of aerosol and cloud condensation nuclei (CCN) in the region, providing a unique opportunity to investigate the biomass burning aerosol (BBA) in the absence of other sources. CCN concentrations at 0.5 % supersaturation and aerosol size and chemical properties were measured at the Australian Tropical Atmospheric Research Station (ATARS) during June 2014. CCN concentrations reached over 104 cm-3 when frequent and close fires were burning - up to 45 times higher than periods with no fires. Both the size distribution and composition of BBA appeared to significantly influence CCN concentrations. A distinct diurnal trend in the proportion of BBA activating to cloud droplets was observed, with an activation ratio of 40 ± 20 % during the night and 60 ± 20 % during the day. BBA was, on average, less hygroscopic during the night (κ = 0. 04 ± 0.03) than during the day (κ = 0.07 ± 0.05), with a maximum typically observed just before midday. Size-resolved composition of BBA showed that organics comprised a constant 90 % of the aerosol volume for aerodynamic diameters between 100 and 200 nm. While this suggests that the photochemical oxidation of organics led to an increase in the hygroscopic growth and an increase in daytime activation ratios, it does not explain the decrease in hygroscopicity after midday. Modelled CCN concentrations assuming typical continental hygroscopicities produced very large overestimations of up to 200 %. Smaller, but still significant, overpredictions up to ˜ 100 % were observed using aerosol mass spectrometer (AMS)- and hygroscopicity tandem differential mobility analyser (H-TDMA)-derived hygroscopicities as well as campaign night and day averages. The largest estimations in every case occurred during the night, when the small variations in very weakly hygroscopic species corresponded to large

  2. 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.

  3. Chemical Modification of Nanotubes for Composites

    NASA Technical Reports Server (NTRS)

    Samulski, Edward T.

    2003-01-01

    In the production of mesoscopically-engineered materials based on single-walled carbon nanotubes (SWNTs), monitoring the stages of chemical modification will be an important step in the fabrication of usable composite materials. In our research program we developed tools for studying high-temperature composites with a long-term goal of having such instrumentation available for SWNT composite analyses.

  4. Semi-volatile inorganic species: importance for atmospheric chemical composition on diurnal and seasonal timescales

    NASA Astrophysics Data System (ADS)

    Pearce, Hana; Mann, Graham; Arnold, Stephen; O'Connor, Fiona; Benduhn, Francois; Rumbold, Steven; Pringle, Kirsty

    2016-04-01

    Nitrate aerosol has become an important driver of reduced European air quality and climate forcing, following reductions in sulphate precursor emissions since the 1980s, and is expected to be more influential in future decades. Measurements from the European Integrated Project on Aerosol and Cloud Climate Air Quality Interactions (EUCAARI) field campaign have shown that semi-volatile aerosol species such as ammonium nitrate can comprise a major component of the sub-micron particulate matter, particularly in high pollution episodes. This presentation will assess the contribution of semi-volatile inorganic aerosol to diurnal and seasonal cycles in atmospheric chemical composition over Europe. We use the UM-UKCA composition-climate model, including the GLOMAP interactive aerosol microphysics module and a recently developed 'hybrid' dissolution solver (HyDis) to accurately represent size-resolved partitioning of ammonia and nitric acid to the particle phase. In particular, we evaluate simulated size-resolved composition variations over Europe through the diurnal cycle, comparing hourly model output to Aerosol Mass Spectrometer observations at several sites during 2008. We will present the results of this composition analysis, in addition to model evaluation from comparisons with European Monitoring for Environmental Protection (EMEP) network and EUCAARI field campaign observations.

  5. Size-resolved aerosol composition at an urban and a rural site in the Po Valley in summertime: implications for secondary aerosol formation

    NASA Astrophysics Data System (ADS)

    Sandrini, Silvia; van Pinxteren, Dominik; Giulianelli, Lara; Herrmann, Hartmut; Poulain, Laurent; Facchini, Maria Cristina; Gilardoni, Stefania; Rinaldi, Matteo; Paglione, Marco; Turpin, Barbara J.; Pollini, Francesca; Bucci, Silvia; Zanca, Nicola; Decesari, Stefano

    2016-09-01

    The aerosol size-segregated chemical composition was analyzed at an urban (Bologna) and a rural (San Pietro Capofiume) site in the Po Valley, Italy, during June and July 2012, by ion-chromatography (major water-soluble ions and organic acids) and evolved gas analysis (total and water-soluble carbon), to investigate sources and mechanisms of secondary aerosol formation during the summer. A significant enhancement of secondary organic and inorganic aerosol mass was observed under anticyclonic conditions with recirculation of planetary boundary layer air but with substantial differences between the urban and the rural site. The data analysis, including a principal component analysis (PCA) on the size-resolved dataset of chemical concentrations, indicated that the photochemical oxidation of inorganic and organic gaseous precursors was an important mechanism of secondary aerosol formation at both sites. In addition, at the rural site a second formation process, explaining the largest fraction (22 %) of the total variance, was active at nighttime, especially under stagnant conditions. Nocturnal chemistry in the rural Po Valley was associated with the formation of ammonium nitrate in large accumulation-mode (0.42-1.2 µm) aerosols favored by local thermodynamic conditions (higher relative humidity and lower temperature compared to the urban site). Nocturnal concentrations of fine nitrate were, in fact, on average 5 times higher at the rural site than in Bologna. The water uptake by this highly hygroscopic compound under high RH conditions provided the medium for increased nocturnal aerosol uptake of water-soluble organic gases and possibly also for aqueous chemistry, as revealed by the shifting of peak concentrations of secondary compounds (water-soluble organic carbon (WSOC) and sulfate) toward the large accumulation mode (0.42-1.2 µm). Contrarily, the diurnal production of WSOC (proxy for secondary organic aerosol) by photochemistry was similar at the two sites but

  6. Phase Partitioning of Soluble Trace Gases with Size-Resolved Aerosols during the Nitrogen, Aerosol Composition, and Halogens on a Tall Tower (NACHTT) Campaign

    NASA Astrophysics Data System (ADS)

    Young, A.; Keene, W. C.; Pszenny, A.; Sander, R.; Maben, J. R.; Warrick-Wriston, C.; Bearekman, R.

    2011-12-01

    During February and March 2011, size-resolved and bulk aerosol were sampled at 22 m above the surface over nominal 12-hour (daytime and nighttime) intervals from the Boulder Atmospheric Observatory tower (40.05 N, 105.01 W, 1584-m elevation). Samples were analyzed for major organic and inorganic ionic constituents by high performance ion chromatography (IC). Soluble trace gases (HCl, HNO3, NH3, HCOOH, and CH3COOH) were sampled in parallel over 2-hour intervals with tandem mist chambers and analyzed on site by IC. NH4+, NO3-, and SO42- were the major ionic components of aerosols (median values of 57.7, 34.5, and 7.3 nmol m-3 at STP, respectively, N = 45) with 86%, 82%, and 82%, respectively, associated with sub-μm size fractions. Cl- and Na+ were present at significant concentrations (median values of 6.8 and 6.6 nmol m-3, respectively) but were associated primarily with super-μm size fractions (75% and 78%, respectively). Median values (and ranges) for HCl, HNO3, and NH3 were 21 (<20-1257), 120 (<45-1638), and 5259 (<1432-48,583) pptv, respectively. Liquid water contents of size-resolved aerosols and activity coefficients for major ionic constituents were calculated with the Extended Aerosol Inorganic Model II and IV (E-AIM) based on the measured aerosol composition, RH, temperature, and pressure. Size-resolved aerosol pHs were inferred from the measured phase partitioning of HCl, HNO3, and NH3. Major controls of phase partitioning and associated chemical dynamics will be presented.

  7. In situ vertical profiles of aerosol extinction, mass, and composition over the southeast United States during SENEX and SEAC4RS: observations of a modest aerosol enhancement aloft

    NASA Astrophysics Data System (ADS)

    Wagner, N. L.; Brock, C. A.; Angevine, W. M.; Beyersdorf, A.; Campuzano-Jost, P.; Day, D.; de Gouw, J. A.; Diskin, G. S.; Gordon, T. D.; Graus, M. G.; Holloway, J. S.; Huey, G.; Jimenez, J. L.; Lack, D. A.; Liao, J.; Liu, X.; Markovic, M. Z.; Middlebrook, A. M.; Mikoviny, T.; Peischl, J.; Perring, A. E.; Richardson, M. S.; Ryerson, T. B.; Schwarz, J. P.; Warneke, C.; Welti, A.; Wisthaler, A.; Ziemba, L. D.; Murphy, D. M.

    2015-06-01

    Vertical profiles of submicron aerosol from in situ aircraft-based measurements were used to construct aggregate profiles of chemical, microphysical, and optical properties. These vertical profiles were collected over the southeastern United States (SEUS) during the summer of 2013 as part of two separate field studies: the Southeast Nexus (SENEX) study and the Study of Emissions and Atmospheric Composition, Clouds, and Climate Coupling by Regional Surveys (SEAC4RS). Shallow cumulus convection was observed during many profiles. These conditions enhance vertical transport of trace gases and aerosol and create a cloudy transition layer on top of the sub-cloud mixed layer. The trace gas and aerosol concentrations in the transition layer were modeled as a mixture with contributions from the mixed layer below and the free troposphere above. The amount of vertical mixing, or entrainment of air from the free troposphere, was quantified using the observed mixing ratio of carbon monoxide (CO). Although the median aerosol mass, extinction, and volume decreased with altitude in the transition layer, they were ~10 % larger than expected from vertical mixing alone. This enhancement was likely due to secondary aerosol formation in the transition layer. Although the transition layer enhancements of the particulate sulfate and organic aerosol (OA) were both similar in magnitude, only the enhancement of sulfate was statistically significant. The column integrated extinction, or aerosol optical depth (AOD), was calculated for each individual profile, and the transition layer enhancement of extinction typically contributed less than 10 % to the total AOD. Our measurements and analysis were motivated by two recent studies that have hypothesized an enhanced layer of secondary aerosol aloft to explain the summertime enhancement of AOD (2-3 times greater than winter) over the southeastern United States. The first study attributes the layer aloft to secondary organic aerosol (SOA) while

  8. Modal structure of chemical mass size distribution in the high Arctic aerosol

    NASA Astrophysics Data System (ADS)

    Hillamo, Risto; Kerminen, Veli-Matti; Aurela, Minna; MäKelä, Timo; Maenhaut, Willy; Leek, Caroline

    2001-11-01

    Chemical mass size distributions of aerosol particles were measured in the remote marine boundary layer over the central Arctic Ocean as part of the Atmospheric Research Program on the Arctic Ocean Expedition 1996 (AOE-96). An inertial impaction method was used to classify aerosol particles into different size classes for subsequent chemical analysis. The particle chemical composition was determined by ion chromatography and by the particle-induced X-ray emission technique. Continuous particle size spectra were extracted from the raw data using a data inversion method. Clear and varying modal structures for aerosols consisting of primary sea-salt particles or of secondary particles related to dimethyl sulfide emissions were found. Concentration levels of all modes decreased rapidly when the distance from open sea increased. In the submicrometer size range the major ions found by ion chromatography were sulfate, methane sulfonate, and ammonium. They had most of the time a clear Aitken mode and one or two accumulation modes, with aerodynamic mass median diameters around 0.1 μm, 0.3 μm, and between 0.5-1.0 μm, respectively. The overall submicron size distributions of these three ions were quite similar, suggesting that they were internally mixed over most of this size range. The corresponding modal structure was consistent with the mass size distributions derived from the particle number size distributions measured with a differential mobility particle sizer. The Aitken to accumulation mode mass ratio for nss-sulfate and MSA was substantially higher during clear skies than during cloudy periods. Primary sea-salt particles formed a mode with an aerodynamic mass median diameter around 2 μm. In general, the resulting continuous mass size distributions displayed a clear modal structure consistent with our understanding of the two known major source mechanisms. One is the sea-salt aerosol emerging from seawater by bubble bursting. The other is related to

  9. Chemical properties and morphology of Marine Aerosol in the Mediterranean atmosphere: a mesocosm study

    NASA Astrophysics Data System (ADS)

    D'Anna, Barbara; Sellegri, Karine; Charrière, Bruno; Sempéré, Richard; Mas, Sébastien; Marchand, Nicolas; George, Christian; Même, Aurèlie; R'mili, Badr; Delmont, Anne; Schwier, Allison; Rose, Clémence; Colomb, Aurèlie; Pey, Jorge; Langley Dewitt, Helen

    2014-05-01

    The Mediterranean Sea is a special marine environment characterized by low biological activity and high anthropogenic pressure. It is often difficult to discriminate the contribution of Primary Sea Salt Aerosol formed at the sea surface from background level of the aerosol. An alternative tool to study the sea-air exchanges in a controlled environment is provided by the mesocosms, which represent an important link between field studies and laboratory experiments. The sea-air transfer of particles and gases was investigated in relation to water chemical composition and biological activity during a mesocosm experiment within the SAM project (Sources of marine Aerosol in the Mediterranean) at the Oceanographic and Marine Station STARESO in Western Corsica (May 2013). Three 2 m mesocosms were filled with screened (<1000 µm) 2260 L of subsurface (1 m) seawater and covered with a transparent Teflon film dome to minimize atmospheric contamination. The mesocosms were equipped with a pack of optical and physicochemical sensors and received different treatments: one was left unchanged as control and two were enriched by addition of nitrates and phosphates respecting Redfield ratio (N:P = 16). The evolution of the three systems was followed for 20 days. The set of sensors in each mesocosm was allowed to monitor, at high frequency (every 10 min), the water temperature, conductivity, pH, incident light, fluorescence of chlorophyll a and dissolved oxygen concentration. The mesocosm seawaters were daily sampled for chemical (colored dissolved organic matter, particulate matter and related polar compounds, transparent polysaccharides and nutrients concentration) and biological (chlorophyll a, virus, phytoplankton and zooplankton) analyses. Both dissolved and gaseous VOCs were also analyzed. In addition, few liters of seawater from each mesocosm were daily and immediately collected and transferred to a bubble-bursting apparatus to simulate nascent sea spray aerosol. On

  10. Elemental composition of urban aerosol collected in Florence, Italy

    NASA Astrophysics Data System (ADS)

    Lucarelli, F.; Mandò, P. A.; Nava, S.; Prati, P.; Zucchiatti, A.

    2000-03-01

    An extensive investigation is in progress aiming at the characterisation of the air particulate composition in Florence. The aim is to determine the aerosol elemental concentrations as well to identify pollution sources. For our investigation, we use the external PIXE-PIGE beam facility of the Van de Graaff accelerator of INFN at the Physics Department of the Florence University. We report here an overview of the results of the PIXE analysis of a long temporal series (about 1 yr) of PM 10 particulate collected on Millipore filters on a daily basis in three different sites (characterised by different urban settings). Daily concentrations of more than 20 elements have been obtained. From the observed elemental concentrations seasonal variation were found. A relevant decrease of S, Pb and Br levels has been found with respect to 10 yr ago. Four main sources (traffic, sulphates, soil-dust and wind-transported sea-salt) have been extracted with the help of factor analysis.

  11. Methodology for the passive detection and discrimination of chemical and biological aerosols

    NASA Astrophysics Data System (ADS)

    Marinelli, William J.; Shokhirev, Kirill N.; Konno, Daisei; Rossi, David C.; Richardson, Martin

    2013-05-01

    The standoff detection and discrimination of aerosolized biological and chemical agents has traditionally been addressed through LIDAR approaches, but sensor systems using these methods have yet to be deployed. We discuss the development and testing of an approach to detect these aerosols using the deployed base of passive infrared hyperspectral sensors used for chemical vapor detection. The detection of aerosols requires the inclusion of down welling sky and up welling ground radiation in the description of the radiative transfer process. The wavelength and size dependent ratio of absorption to scattering provides much of the discrimination capability. The approach to the detection of aerosols utilizes much of the same phenomenology employed in vapor detection; however, the sensor system must acquire information on non-line-of-sight sources of radiation contributing to the scattering process. We describe the general methodology developed to detect chemical or biological aerosols, including justifications for the simplifying assumptions that enable the development of a real-time sensor system. Mie scattering calculations, aerosol size distribution dependence, and the angular dependence of the scattering on the aerosol signature will be discussed. This methodology will then be applied to two test cases: the ground level release of a biological aerosol (BG) and a nonbiological confuser (kaolin clay) as well as the debris field resulting from the intercept of a cruise missile carrying a thickened VX warhead. A field measurement, conducted at the Utah Test and Training Range will be used to illustrate the issues associated with the use of the method.

  12. Microbial Control of Sea Spray Aerosol Composition: A Tale of Two Blooms

    PubMed Central

    2015-01-01

    With the oceans covering 71% of the Earth, sea spray aerosol (SSA) particles profoundly impact climate through their ability to scatter solar radiation and serve as seeds for cloud formation. The climate properties can change when sea salt particles become mixed with insoluble organic material formed in ocean regions with phytoplankton blooms. Currently, the extent to which SSA chemical composition and climate properties are altered by biological processes in the ocean is uncertain. To better understand the factors controlling SSA composition, we carried out a mesocosm study in an isolated ocean-atmosphere facility containing 3,400 gallons of natural seawater. Over the course of the study, two successive phytoplankton blooms resulted in SSA with vastly different composition and properties. During the first bloom, aliphatic-rich organics were enhanced in submicron SSA and tracked the abundance of phytoplankton as indicated by chlorophyll-a concentrations. In contrast, the second bloom showed no enhancement of organic species in submicron particles. A concurrent increase in ice nucleating SSA particles was also observed only during the first bloom. Analysis of the temporal variability in the concentration of aliphatic-rich organic species, using a kinetic model, suggests that the observed enhancement in SSA organic content is set by a delicate balance between the rate of phytoplankton primary production of labile lipids and enzymatic induced degradation. This study establishes a mechanistic framework indicating that biological processes in the ocean and SSA chemical composition are coupled not simply by ocean chlorophyll-a concentrations, but are modulated by microbial degradation processes. This work provides unique insight into the biological, chemical, and physical processes that control SSA chemical composition, that when properly accounted for may explain the observed differences in SSA composition between field studies. PMID:27162962

  13. 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

  14. Long-term Measurements of Submicrometer Aerosol Chemistry at the Southern Great Plains (SGP) Using an Aerosol Chemical Speciation Monitor (ACSM)

    SciTech Connect

    Parworth, Caroline; Fast, Jerome D.; Mei, Fan; Shippert, Timothy R.; Sivaraman, Chitra; Tilp, Alison; Watson, Thomas; Zhang, Qi

    2015-04-01

    In this study the long-term trends of non-refractory submicrometer aerosol (NR-PM1) composition and mass concentration measured by an Aerosol Chemical Speciation Monitor (ACSM) at the U.S. Department of Energy’s Southern Great Plains (SGP) site are discussed. Over the period of 19 months (Nov. 20, 2010 – June 2012) highly time resolved (~30 min.) NR-PM1 data was recorded. Using this dataset the value-added product (VAP) of deriving organic aerosol components (OACOMP) is introduced. With this VAP, multivariate analysis of the measured organic mass spectral matrix can be performed on long term data to return organic aerosol (OA) factors that are associated with distinct sources, evolution processes, and physiochemical properties. Three factors were obtained from this VAP including two oxygenated OA (OOA) factors, differing in degrees of oxidation, and a biomass burning OA (BBOA) factor. Back trajectory analyses were performed to investigate possible sources of major NR-PM1 species at the SGP site. Organics dominated NR-PM1 mass concentration for the majority of the study with the exception of winter, when nitrate increased due to transport of precursor species from surrounding urban and agricultural areas and also due to cooler temperatures. Sulfate mass concentrations showed little seasonal variation with mixed regional and local sources. In the spring BBOA emissions increased and were mainly associated with local fires. Isoprene and carbon monoxide emission rates were computed by the Model of Emissions of Gases and Aerosols from Nature (MEGAN) to represent the spatial distribution of biogenic and anthropogenic sources, respectively. From this model there is evidence to support that biogenic emissions from the southeast contribute to SOA formation at the SGP site during the summer.

  15. Aerosols

    Atmospheric Science Data Center

    2013-04-17

    ... article title:  Aerosols over Central and Eastern Europe     View Larger Image ... last weeks of March 2003, widespread aerosol pollution over Europe was detected by several satellite-borne instruments. The Multi-angle ...

  16. A chemical climatology of lower tropospheric trace gases and aerosols over the mid-Atlantic region

    NASA Astrophysics Data System (ADS)

    Hains, Jennifer Carrie

    2007-12-01

    Ozone and aerosols affect air quality, visibility and human health. The University of Maryland research aircraft conducted flights over the Mid-Atlantic region between 1995 and 2005 to characterize pollution events. I developed a chemical climatology of trace gases and aerosols that can be used to validate and improve models. O3 and SO2 measured aboard the aircraft were compared with O3 and SO2 generated with the Community Multiscale Air Quality (CMAQ). In general, CMAQ under-estimates O3 above 500 m and over-estimates O3 below 500 m (possible reasons for this include chemistry not being properly represented in the model). A sensitivity test of the rate of photolysis of NO2 was performed and improving the photochemistry did improve the modeled O3. CMAQ over-predicts the SO2 column content by about 50%, possibly because the model gives SO2 too long a lifetime. To test this theory I developed a method for calculating the SO2 lifetime using in-situ measurements. The mean SO2 lifetime was 19 +/- 7 hours for measurements made in the daytime in the summer in the Mid-Atlantic region with in-cloud processes responsible for ˜80% of the removal. I made comparisons of three aerosol sampling systems and found the uncertainty of PM2.5, sulfate, and ammonium measured with the Speciation Trends Network is larger than what has been reported and is at least 20%. I have developed clustering methodologies to group back trajectories associated with aircraft profiles as well as group trace gas and aerosol profiles by size and shape. The first clustering method produced eight distinct meteorological regimes associated with pollution and haze events. I quantified the amount of O3 transported for each meteorological regime. Using the second method, I found a strong correlation between O3 profiles and point source NOx emissions. The comparisons of model and measured profiles, comparisons of surface measurements, and clustering methods are used to explain sources, sinks and distributions

  17. 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

  18. Intercomparison of an Aerosol Chemical Speciation Monitor (ACSM) with ambient fine aerosol measurements in downtown Atlanta, Georgia

    NASA Astrophysics Data System (ADS)

    Budisulistiorini, S. H.; Canagaratna, M. R.; Croteau, P. L.; Baumann, K.; Edgerton, E. S.; Kollman, M. S.; Ng, N. L.; Verma, V.; Shaw, S. L.; Knipping, E. M.; Worsnop, D. R.; Jayne, J. T.; Weber, R. J.; Surratt, J. D.

    2014-07-01

    Currently, there are a limited number of field studies that evaluate the long-term performance of the Aerodyne Aerosol Chemical Speciation Monitor (ACSM) against established monitoring networks. In this study, we present seasonal intercomparisons of the ACSM with collocated fine aerosol (PM2.5) measurements at the Southeastern Aerosol Research and Characterization (SEARCH) Jefferson Street (JST) site near downtown Atlanta, GA, during 2011-2012. Intercomparison of two collocated ACSMs resulted in strong correlations (r2 > 0.8) for all chemical species, except chloride (r2 = 0.21) indicating that ACSM instruments are capable of stable and reproducible operation. In general, speciated ACSM mass concentrations correlate well (r2 > 0.7) with the filter-adjusted continuous measurements from JST, although the correlation for nitrate is weaker (r2 = 0.55) in summer. Correlations of the ACSM NR-PM1 (non-refractory particulate matter with aerodynamic diameter less than or equal to 1 μm) plus elemental carbon (EC) with tapered element oscillating microbalance (TEOM) PM2.5 and Federal Reference Method (FRM) PM1 mass are strong with r2 > 0.7 and r2 > 0.8, respectively. Discrepancies might be attributed to evaporative losses of semi-volatile species from the filter measurements used to adjust the collocated continuous measurements. This suggests that adjusting the ambient aerosol continuous measurements with results from filter analysis introduced additional bias to the measurements. We also recommend to calibrate the ambient aerosol monitoring instruments using aerosol standards rather than gas-phase standards. The fitting approach for ACSM relative ionization for sulfate was shown to improve the comparisons between ACSM and collocated measurements in the absence of calibrated values, suggesting the importance of adding sulfate calibration into the ACSM calibration routine.

  19. Overview of Aerosol Distribution

    NASA Technical Reports Server (NTRS)

    Kaufman, Yoram

    2005-01-01

    Our knowledge of atmospheric aerosols (smoke, pollution, dust or sea salt particles, small enough to be suspended in the air), their evolution, composition, variability in space and time and interaction with clouds and precipitation is still lacking despite decades of research. Understanding the global aerosol system is fundamental for progress in climate change and hydrological cycle research. While a single instrument was used to demonstrate 50 years ago that the global CO2 levels are rising, posing threat of global warming, we need an array of satellites and field measurements coupled with chemical transport models to understand the global aerosol system. This complexity of the aerosol problem results from their short lifetime (1 week) and variable chemical composition. A new generation of satellites provides exciting opportunities to measure the global distribution of aerosols, distinguishing natural from anthropogenic aerosol and measuring their interaction with clouds and climate. I shall discuss these topics and application of the data to air quality monitoring.

  20. Long-term measurements of submicrometer aerosol chemistry at the Southern Great Plains (SGP) using an Aerosol Chemical Speciation Monitor (ACSM)

    DOE PAGES

    Parworth, Caroline; Tilp, Alison; Fast, Jerome; ...

    2015-04-01

    In this study the long-term trends of non-refractory submicrometer aerosol (NR-PM1) composition and mass concentration measured by an Aerosol Chemical Speciation Monitor (ACSM) at the Atmospheric Radiation Measurement (ARM) program's Southern Great Plains (SGP) site are discussed. NR-PM1 data was recorded at ~30 min intervals over a period of 19 months between November 2010 and June 2012. Positive Matrix Factorization (PMF) was performed on the measured organic mass spectral matrix using a rolling window technique to derive factors associated with distinct sources, evolution processes, and physiochemical properties. The rolling window approach also allows us to capture the dynamic variations ofmore » the chemical properties in the organic aerosol (OA) factors over time. Three OA factors were obtained including two oxygenated OA (OOA) factors, differing in degrees of oxidation, and a biomass burning OA (BBOA) factor. Back trajectory analyses were performed to investigate possible sources of major NR-PM1 species at the SGP site. Organics dominated NR-PM1 mass concentration for the majority of the study with the exception of winter, when ammonium nitrate increases due to transport of precursor species from surrounding urban and agricultural areas and also due to cooler temperatures. Sulfate mass concentrations have little seasonal variation with mixed regional and local sources. In the spring BBOA emissions increase and are mainly associated with local fires. Isoprene and carbon monoxide emission rates were obtained by the Model of Emissions of Gases and Aerosols from Nature (MEGAN) and the 2011 U.S. National Emissions Inventory to represent the spatial distribution of biogenic and anthropogenic sources, respectively. The combined spatial distribution of isoprene emissions and air mass trajectories suggest that biogenic emissions from the southeast contribute to SOA formation at the SGP site during the summer.« less

  1. Long-term measurements of submicrometer aerosol chemistry at the Southern Great Plains (SGP) using an Aerosol Chemical Speciation Monitor (ACSM)

    SciTech Connect

    Parworth, Caroline; Tilp, Alison; Fast, Jerome; Mei, Fan; Shippert, Tim; Sivaraman, Chitra; Watson, Thomas; Zhang, Qi

    2015-04-01

    In this study the long-term trends of non-refractory submicrometer aerosol (NR-PM1) composition and mass concentration measured by an Aerosol Chemical Speciation Monitor (ACSM) at the Atmospheric Radiation Measurement (ARM) program's Southern Great Plains (SGP) site are discussed. NR-PM1 data was recorded at ~30 min intervals over a period of 19 months between November 2010 and June 2012. Positive Matrix Factorization (PMF) was performed on the measured organic mass spectral matrix using a rolling window technique to derive factors associated with distinct sources, evolution processes, and physiochemical properties. The rolling window approach also allows us to capture the dynamic variations of the chemical properties in the organic aerosol (OA) factors over time. Three OA factors were obtained including two oxygenated OA (OOA) factors, differing in degrees of oxidation, and a biomass burning OA (BBOA) factor. Back trajectory analyses were performed to investigate possible sources of major NR-PM1 species at the SGP site. Organics dominated NR-PM1 mass concentration for the majority of the study with the exception of winter, when ammonium nitrate increases due to transport of precursor species from surrounding urban and agricultural areas and also due to cooler temperatures. Sulfate mass concentrations have little seasonal variation with mixed regional and local sources. In the spring BBOA emissions increase and are mainly associated with local fires. Isoprene and carbon monoxide emission rates were obtained by the Model of Emissions of Gases and Aerosols from Nature (MEGAN) and the 2011 U.S. National Emissions Inventory to represent the spatial distribution of biogenic and anthropogenic sources, respectively. The combined spatial distribution of isoprene emissions and air mass trajectories suggest that biogenic emissions from the southeast contribute to SOA formation at the SGP site during the summer.

  2. Marine biogeochemical influence on primary sea spray aerosol composition in the Southern Ocean: predictions from a mechanistic model

    NASA Astrophysics Data System (ADS)

    McCoy, D.; Burrows, S. M.; Elliott, S.; Frossard, A. A.; Russell, L. M.; Liu, X.; Ogunro, O. O.; Easter, R. C.; Rasch, P. J.

    2014-12-01

    Remote marine clouds, such as those over the Southern Ocean, are particularly sensitive to variations in the concentration and chemical composition of aerosols that serve as cloud condensation nuclei (CCN). Observational evidence indicates that the organic content of fine marine aerosol is greatly increased during the biologically active season near strong phytoplankton blooms in certain locations, while being nearly constant in other locations. We have recently developed a novel modeling framework that mechanistically links the organic fraction of submicron sea spray to ocean biogeochemistry (Burrows et al., in discussion, ACPD, 2014; Elliott et al., ERL, 2014). Because of its combination of large phytoplankton blooms and high wind speeds, the Southern Ocean is an ideal location for testing our understanding of the processes driving the enrichment of organics in sea spray aerosol. Comparison of the simulated OM fraction with satellite observations shows that OM fraction is a statistically significant predictor of cloud droplet number concentration over the Southern Ocean. This presentation will focus on predictions from our modeling framework for the Southern Ocean, specifically, the predicted geographic gradients and seasonal cycles in the aerosol organic matter and its functional group composition. The timing and location of a Southern Ocean field campaign will determine its utility in observing the effects of highly localized and seasonal phytoplankton blooms on aerosol composition and clouds. Reference cited: Burrows, S. M., Ogunro, O., Frossard, A. A., Russell, L. M., Rasch, P. J., and Elliott, S.: A physically-based framework for modelling the organic fractionation of sea spray aerosol from bubble film Langmuir equilibria, Atmos. Chem. Phys. Discuss., 14, 5375-5443, doi:10.5194/acpd-14-5375-2014, 2014. Elliott, S., Burrows, S. M., Deal, C., Liu, X., Long, M., Ogunro, O., Russell, L. M., and Wingenter O.. "Prospects for simulating macromolecular surfactant

  3. Physical and chemical properties of aerosols at a coastal site Paposo (Chile) during VOCALS campaign

    NASA Astrophysics Data System (ADS)

    Cordova, A. M.; Chand, D.; Wood, R.; Wallace, D.; Hegg, D. A.; Shaw, G. E.; Krejci, R.; Fochesatto, G. J.; Gallardo, L.

    2009-12-01

    One of the primary goals of the VOCALS (VAMOS* Ocean-Cloud-Atmosphere-Land Study) Regional Experiment (REx) and associated modeling program is an improved understanding of aerosol indirect effects over the southeast Pacific (SEP). Details on the program are available online at www.eol.ucar.edu/projects/vocals/. To this end, detailed aerosol physical and chemical measurements were made during REx at a coastal land site at Paposo (25o 0.4' S, 70o 27.011' W, 690 masl) in northern Chile, a site ideally positioned for studying continental aerosol sources advecting over the SEP. We present initial analysis of data from Paposo. Detailed measurements of aerosol properties were made from mid October to mid November 2008. Observations from optical particle counters (OPC), nephelometers, aethalometer, scanning mobility particle sizer (SMPS) and the chemical analysis of the submicron aerosols samples collected on teflon filters are being used in this study. Large variations in aerosols parameters were observed which corresponded with changes in meteorology, as determined using trajectory analysis. Ion Chromatograph (IC) analysis of submicron aerosol samples shows that about 41% of submicron mass is sulfate. The light scattering coefficient shows a strong non-linear correlation with aerosol size observed using an OPC. Detailed results will be presented in the AGU meeting.

  4. Importance of Physico-Chemical Properties of Aerosols in the Formation of Arctic Ice Clouds

    NASA Astrophysics Data System (ADS)

    Keita, S. A.; Girard, E.

    2014-12-01

    Ice clouds play an important role in the Arctic weather and climate system but interactions between aerosols, clouds and radiation are poorly understood. Consequently, it is essential to fully understand their properties and especially their formation process. Extensive measurements from ground-based sites and satellite remote sensing reveal the existence of two Types of Ice Clouds (TICs) in the Arctic during the polar night and early spring. TIC-1 are composed by non-precipitating very small (radar-unseen) ice crystals whereas TIC-2 are detected by both sensors and are characterized by a low concentration of large precipitating ice crystals. It is hypothesized that TIC-2 formation is linked to the acidification of aerosols, which inhibit the ice nucleating properties of ice nuclei (IN). As a result, the IN concentration is reduced in these regions, resulting to a smaller concentration of larger ice crystals. Over the past 10 years, several parameterizations of homogeneous and heterogeneous ice nucleation have been developed to reflect the various physical and chemical properties of aerosols. These parameterizations are derived from laboratory studies on aerosols of different chemical compositions. The parameterizations are also developed according to two main approaches: stochastic (that nucleation is a probabilistic process, which is time dependent) and singular (that nucleation occurs at fixed conditions of temperature and humidity and time-independent). This research aims to better understand the formation process of TICs using a newly-developed ice nucleation parameterizations. For this purpose, we implement some parameterizations (2 approaches) into the Limited Area version of the Global Multiscale Environmental Model (GEM-LAM) and use them to simulate ice clouds observed during the Indirect and Semi-Direct Arctic Cloud (ISDAC) in Alaska. We use both approaches but special attention is focused on the new parameterizations of the singular approach. Simulation

  5. Chemical characterisation of semi-volatile and aerosol compounds from the photooxidation of toluene and NOx

    NASA Astrophysics Data System (ADS)

    White, Stephen J.; Jamie, Ian M.; Angove, Dennys E.

    2014-02-01

    The chemical composition of a gas phase and secondary organic aerosol (SOA) mixture from toluene photooxidation in NOx was determined. Aerosol from toluene photooxidation was generated in a smog chamber and was collected onto glass fibre filters along with those gas phase compounds which adhered to the filter. The filter bound organic material was extracted, derivatised with O-2,3,4,5,6-pentafluorobenzyl hydroxylamine (PFBHA) and N,O-bistrimethylsilyl-trifluoroacetamide (BSTFA), then analysed using gas chromatography-mass spectrometry (GC-MS). Compound identification was aided by the use of isotopically-labelled toluene. The effect of humidity on product formation was investigated by raising water vapour concentration in one experiment. Sixty compounds were identified, of which twenty had not been identified from toluene photooxidation previously. Small carboxylic acids and dicarbonyls provided the highest proportion of identifiable compounds by relative response. The use of water to extract the filter samples resulted in much higher relative responses for oxocarboxylic acids, such as glyoxylic acid and pyruvic acid, than has been observed in previous studies. The formation of levulinic acid was determined to be due to the reaction of water with aromatic photooxidation products in the gas phase or particle phase of the chamber experiment. Nuclear magnetic resonance (NMR) was used to determine the functional groups of water-extracted organic material, which indicated that the water-soluble components were comprised of compounds which contain similar functional groups, primarily alcohols and carboxylic acids.

  6. The Chemical Composition of Maple Syrup

    ERIC Educational Resources Information Center

    Ball, David W.

    2007-01-01

    Maple syrup is one of several high-sugar liquids that humans consume. However, maple syrup is more than just a concentrated sugar solution. Here, we review the chemical composition of maple syrup. (Contains 4 tables and 1 figure.)

  7. Measurements of HNO3, SO2 High Resolution Aerosol SO4 (sup 2-), and Selected Aerosol Species Aboard the NASA DC-8 Aircraft: During the Transport and Chemical Evolution Over the Pacific Airborne Mission (TRACE-P)

    NASA Technical Reports Server (NTRS)

    Talbot, Robert W.; Dibb, Jack E.

    2004-01-01

    The UNH investigation during TRACE-P provided measurements of selected acidic gases and aerosol species aboard the NASA DC-8 research aircraft. Our investigation focused on measuring HNO3, SO2, and fine (less than 2 microns) aerosol SO4(sup 2-) with two minute time resolution in near-real-time. We also quantified mixing ratios of aerosol ionic species, and aerosol (210)Pb and (7)Be collected onto bulk filters at better than 10 minute resolution. This suite of measurements contributed extensively to achieving the principal objectives of TRACE-P. In the context of the full data set collected by experimental teams on the DC-8, our observations provide a solid basis for assessing decadal changes in the chemical composition and source strength of Asian continental outflow. This region of the Pacific should be impacted profoundly by Asian emissions at this time with significant degradation of air quality over the next few decades. Atmospheric measurements in the western Pacific region will provide a valuable time series to help quantify the impact of Asian anthropogenic activities. Our data also provide important insight into the chemical and physical processes transforming Asian outflow during transport over the Pacific, particularly uptake and reactions of soluble gases on aerosol particles. In addition, the TRACE-P data set provide strong constraints for assessing and improving the chemical fields simulated by chemical transport models.

  8. Marine Primary Aerosol in the Mediterranean atmosphere: physical and chemical properties from a mesocosm study

    NASA Astrophysics Data System (ADS)

    D'anna, B.; Sellegri, K.; Charriere, B.; Sempere, R.; Mas, S.; George, C.; Meme, A.; R'Mili, B.; Schwier, A. N.; Rose, C.

    2013-12-01

    m. The hygroscopic properties were investigated by a CCN device. On-line chemical analysis of the sub-micrometer fraction was performed by a c-TOF-AMS. Off-line analysis of the SSA generated included TEM-EDX , LC-MS and IC, Thermo-optical analysis of EC-OC. The objective of the present study is to investigate the influence of water chemical and biological composition and biological activity on physical and chemical properties of the primary generated aerosol.

  9. Chemical composition of Earth-like planets

    NASA Astrophysics Data System (ADS)

    Ronco, M. P.; Thiabaud, A.; Marboeuf, U.; Alibert, Y.; de Elía, G. C.; Guilera, O. M.

    2015-08-01

    Models of planet formation are mainly focused on the accretion and dynamical processes of the planets, neglecting their chemical composition. In this work, we calculate the condensation sequence of the different chemical elements for a low-mass protoplanetary disk around a solar-type star. We incorporate this sequence of chemical elements (refractory and volatile elements) in our semi-analytical model of planet formation which calculates the formation of a planetary system during its gaseous phase. The results of the semi-analytical model (final distributions of embryos and planetesimals) are used as initial conditions to develope N-body simulations that compute the post-oligarchic formation of terrestrial-type planets. The results of our simulations show that the chemical composition of the planets that remain in the habitable zone has similar characteristics to the chemical composition of the Earth. However, differences exist that can be associated to the dynamical environment in which they were formed.

  10. Aerosol composition and variability in the Baltimore-Washington, DC region

    NASA Astrophysics Data System (ADS)

    Beyersdorf, A. J.; Ziemba, L. D.; Chen, G.; Corr, C. A.; Crawford, J. H.; Diskin, G. S.; Moore, R. H.; Thornhill, K. L.; Winstead, E. L.; Anderson, B. E.

    2015-08-01

    In order to utilize satellite-based aerosol measurements for the determination of air quality, the relationship between aerosol optical properties (wavelength-dependent, column-integrated extinction measured by satellites) and mass measurements of aerosol loading (PM2.5 used for air quality monitoring) must be understood. This connection varies with many factors including those specific to the aerosol type, such as composition, size and hygroscopicity, and to the surrounding atmosphere, such as temperature, relative humidity (RH) and altitude, all of which can vary spatially and temporally. During the DISCOVER-AQ (Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality) project, extensive in-situ atmospheric profiling in the Baltimore, MD-Washington, DC region was performed during fourteen flights in July 2011. Identical flight plans and profile locations throughout the project provide meaningful statistics for determining the variability in and correlations between aerosol loading, composition, optical properties and meteorological conditions. Measured water-soluble aerosol mass was composed primarily of ammonium sulfate (campaign average of 32 %) and organics (57 %). A distinct difference in composition was observed with high-loading days having a proportionally larger percentage of ammonium sulfate (up to 49 %) due to transport from the Ohio River Valley. This composition shift caused a change in the aerosol water-uptake potential (hygroscopicity) such that higher relative contributions of ammonium sulfate increased the bulk aerosol hygroscopicity. These days also tended to have higher relative humidity causing an increase in the water content of the aerosol. Conversely, low aerosol loading days had lower ammonium sulfate and higher black carbon contributions causing lower single scattering albedos (SSAs). The average black carbon concentrations were 240 ng m-3 in the lowest 1 km decreasing to 35 ng m-3

  11. Chemical composition of fat and oil products

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fats and oils are an important dietary component, and contribute to the nutritional and sensory quality of foods. This chapter focuses on the chemical composition of fats and oils, and how these compositions affect the functional properties of fats and oils in foods. The focus will remain on the mos...

  12. 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

  13. 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

  14. Correlations between Optical, Chemical and Physical Properties ofBiomass Burn Aerosols

    SciTech Connect

    Hopkins, Rebecca J.; Lewis, K.; Desyaterik, Yury; Wang, Z.; Tivanski, Alexei V.; Arnott, W.P.; Laskin, Alexander; Gilles, M.K.

    2008-01-29

    Aerosols generated from burning different plant fuels were characterized to determine relationships between chemical, optical and physical properties. Single scattering albedo ({omega}) and Angstrom absorption coefficients ({alpha}{sub ap}) were measured using a photoacoustic technique combined with a reciprocal nephelometer. Carbon-to-oxygen atomic ratios, sp{sup 2} hybridization, elemental composition and morphology of individual particles were measured using scanning transmission X-ray microscopy coupled with near-edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS) and scanning electron microscopy with energy dispersion of X-rays (SEM/EDX). Particles were grouped into three categories based on sp2 hybridization and chemical composition. Measured {omega} (0.4-1.0 at 405 nm) and {alpha}{sub ap} (1.0-3.5) values displayed a fuel dependence. The category with sp{sup 2} hybridization >80% had values of {omega} (<0.5) and {alpha}{sub ap} ({approx}1.25) characteristic of light absorbing soot. Other categories with lower sp2 hybridization (20 to 60%) exhibited higher {omega} (>0.8) and {alpha}{sub ap} (1.0 to 3.5) values, indicating increased absorption spectral selectivity.

  15. Water uptake is independent of the inferred composition of secondary aerosols derived from multiple biogenic VOCs

    NASA Astrophysics Data System (ADS)

    Alfarra, M. R.; Good, N.; Wyche, K. P.; Hamilton, J. F.; Monks, P. S.; Lewis, A. C.; McFiggans, G.

    2013-12-01

    properties of SOA are compared to the averaged carbon oxidation state (OSC) determined using an offline method. These findings do not necessarily suggest that water uptake and chemical composition are not related. Instead, they suggest that either f44 and OSC do not represent the main dominant composition-related factors controlling water uptake of SOA particles, or they may emphasise the possible impact of semi-volatile compounds on limiting the ability of current state-of-the-art techniques to determine the chemical composition and water uptake properties of aerosol particles.

  16. Water uptake is independent of the inferred composition of secondary aerosols derived from multiple biogenic VOCs

    NASA Astrophysics Data System (ADS)

    Alfarra, M. R.; Good, N.; Wyche, K. P.; Hamilton, J. F.; Monks, P. S.; Lewis, A. C.; McFiggans, G. B.

    2013-04-01

    properties of SOA are compared to the averaged carbon oxidation state (OSC) determined using an off-line method. These findings do not necessarily suggest that water uptake and chemical composition are not related. Instead, they suggest that either f44 and OSC do not represent the main dominant composition-related factors controlling water uptake of SOA particles, or they emphasise the possible impact of semi-volatile compounds on limiting the ability of current state-of-the-art techniques to determine the chemical composition and water uptake properties of aerosol particles.

  17. 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)

  18. 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.

  19. Day-of-week trends in carbonaceous aerosol composition in the urban atmosphere

    NASA Astrophysics Data System (ADS)

    Lough, G. C.; Schauer, J. J.; Lawson, D. R.

    The chemical composition of atmospheric particulate matter was measured at two sites near Los Angeles, California, over 3 weeks in July 2001, as part of the Gasoline/Diesel PM Split Study. Samples were composited for organic speciation analysis by day of week at each site to investigate weekly trends in chemical composition of the carbonaceous fraction of particulate matter. Observed weekly trends in elemental carbon (EC), hopanes, steranes, and polynuclear aromatic hydrocarbons (PAHs) indicate increased impacts of motor vehicle traffic on carbonaceous particulate matter concentrations on weekdays relative to weekends. Ambient average EC was approximately 4 times higher in the Friday samples than in Sunday samples at each site. Levoglucosan, a tracer species for biomass burning, and cholesterol, monopalmitin, and monostearin, tracers for food cooking operations, were all highest on Friday and lowest on Sunday. Late-week increases in aliphatic and aromatic diacids present in the particulate phase were also observed. Diacids in particulate matter have been seen to be indicators of secondary organic aerosol formation, and the day-of-week trend observed may be due to weekday increases in volatile precursor species present in the atmosphere.

  20. Modelling of primary aerosols in the chemical transport model MOCAGE: development and evaluation of aerosol physical parameterizations

    NASA Astrophysics Data System (ADS)

    Sič, B.; El Amraoui, L.; Marécal, V.; Josse, B.; Arteta, J.; Guth, J.; Joly, M.; Hamer, P.

    2014-04-01

    This paper deals with recent improvements to the chemical transport model of Météo-France MOCAGE that consists of updates to different aerosol parameterizations. MOCAGE only contains primary aerosol species. We introduced important changes to the aerosol parameterization concerning emissions, wet deposition and sedimentation. For the emissions, size distribution and wind calculations are modified for desert dust aerosols, and a surface sea temperature dependant source function is introduced for sea salt aerosols. Wet deposition is modified toward a more physically realistic representation by introducing re-evaporation of falling rain and snowfall scavenging, and by changing in-cloud scavenging scheme along with calculations of precipitation cloud cover and rain properties. The sedimentation scheme update includes changes regarding the stability and viscosity calculations. Independent data from satellites (MODIS, SEVIRI), the ground (AERONET), and a model inter-comparison project (AeroCom) is compared with MOCAGE simulations and showed that the introduced changes brought a significant improvement on aerosol representation, properties and global distribution. Emitted quantities of desert dust and sea salt, as well their lifetimes, moved closer towards values of AeroCom estimates and the multi-model average. When comparing the model simulations with MODIS aerosol optical depth (AOD) observations over the oceans, the updated model configuration shows a decrease in the bias (from 0.032 to 0.002) and a better correlation (from 0.062 to 0.322) in terms of the geographical distribution and the temporal variability. The updates corrected a strong positive bias in the sea salt representation at high latitudes (from 0.153 to 0.026), and a negative bias in the desert dust representation in the African dust outflow region (from -0.179 to -0.051). The updates in sedimentation produced a modest difference; the bias with MODIS data from 0.002 in the updated configuration went to

  1. Chemical Characterization and Single Scattering Albedo of Atmospheric Aerosols Measured at Amami-Oshima, Southwest Japan, During Spring Seasons

    NASA Astrophysics Data System (ADS)

    Tsuruta, H.; Yabuki, M.; Takamura, T.; Sudo, S.; Yonemura, S.; Shirasuna, Y.; Hirano, K.; Sera, K.; Maeda, T.; Hayasaka, T.; Nakajima, T.

    2008-12-01

    An intensive field program was performed to measure atmospheric aerosols at Amami-Oshima, a small island located at southwest Japan, in the spring season of 2001, 2003, and 2005 under the ACE-Asia, APEX and ABC-EAREX2005 projects. Chemical analysis of the fine and coarse aerosols was made for elemental carbon (EC) and organic carbon, water soluble ions, and trace elements. Single scattering albedo (SSA) of aerosols was independently estimated by two methods. The one (SSAc) is by chemical compositions assuming a half internal mixture between EC and non sea-salt sulfate, and the other (SSAo) is by optical measurements of scattering coefficient and absorption coefficient. The backward trajectory analysis showed that the aerosol concentrations in the air masses arrived at Amami, were much higher from the Asian Continent than from other regions, and two types of aerosol enhancement were observed. The one was caused by polluted air masses from the urban-industrial area of east-coast China, the other was by high mineral dusts due to large- scale dust storms in the desert regions of northwest China. The SSAc was in a range of 0.87-0.98, and in good agreement with the SSAo after some corrections for original scattering and absorption coefficients. The SSAc showed no significant difference between the air masses from the polluted area and the desert regions. The negative correlation between the SSAc and EC was divided into two groups depending on the concentration of non sea-salt sulfate, while the increase in mineral dusts did not show any correlation with the SSAc.

  2. Sensitivity of thermal infrared sounders to the chemical and micro-physical properties of UTLS secondary sulphate aerosols

    NASA Astrophysics Data System (ADS)

    Sellitto, P.; Legras, B.

    2015-08-01

    Monitoring upper tropospheric-lower stratospheric (UTLS) secondary sulphate aerosols and their chemical and micro-physical properties from satellite nadir observations is crucial to better understand their formation and evolution processes and then to estimate their impact to the UTLS chemistry, and on regional and global radiative balance. Here we present a study aimed at the evaluation of the sensitivity of thermal infrared (TIR) satellite nadir observations to the chemical composition and the size distribution of idealized UTLS sulphate aerosol layers. The extinction properties of sulphuric acid/water droplets, for different sulphuric acid mixing ratios and temperatures, are systematically analysed. The extinction coefficients are derived by means of a Mie code, using refractive indexes taken from the GEISA (Gestion et Étude des Informations Spectroscopiques Atmosphériques: Management and Study of Spectroscopic Information) spectroscopic database and log-normal size distributions with different effective radii and number concentrations. IASI (Infrared Atmospheric Sounding Interferometer) pseudo-observations are generated using forward radiative transfer calculations performed with the 4A (Automatized Atmospheric Absorption Atlas) radiative transfer model, to estimate the impact of the extinction of idealized aerosol layers, at typical UTLS conditions, on the brightness temperature spectra observed by this satellite instrument. We found a marked and typical spectral signature of these aerosol layers between 700 and 1200 cm-1, due to the absorption bands of the sulphate and bi-sulphate ions and the undissociated sulphuric acid, with the main absorption peaks at 1170 and 905 cm-1. The dependence of the aerosol spectral signature to the sulphuric acid mixing ratio, and effective number concentration and radius, as well as the role of interferring parameters like the ozone, sulphur dioxide, carbon dioxide and ash absorption, and temperature and water vapour profile

  3. Summer-winter differences in the relationships among background southeastern U.S. aerosol optical, micro-physical, and chemical properties

    NASA Astrophysics Data System (ADS)

    Sherman, J. P.; Link, M.; Zhou, Y.

    2015-12-01

    Relationships among aerosol optical, micro-physical, and chemical properties are useful for evaluating regional climate models, developing satellite-based aerosol retrievals, and understanding aerosol sources and processes. Since aerosol loading and optical properties vary primarily on seasonal scales in the southeastern U.S., it is important that such studies be carried out over multiple seasons but few (if any) such multi-season studies have been conducted in the region. The high-elevation, semi-rural AppalAIR facility at Appalachian State University in Boone, NC (1080m ASL, 36.210N, 81.690W) is home to the only co-located NOAA-ESRL and AERONET monitoring sites in the eastern U.S. Measurements of size-resolved, non-refractory sub-1μm aerosol composition were also made by a co-located AMS during the 2012-2013 summers and 2013 winter. Systematic relationships among aerosol optical, microphysical, and chemical properties were developed to better understand aerosol sources and processes and for use in higher-dimension aerosol classification schemes. Some of the major findings will be presented. Higher values of lower tropospheric aerosol light scattering coefficient at 550nm (a proxy for aerosol loading) are associated with higher single-scattering albedo (SSA) and lower hemispheric backscatter fraction (b) during both summer and winter. Absorption Angstrom exponent (AAE) is typically well under 1 during summer and near 1.3-1.4 during winter. Lowest summer AAE values coincide with large, highly-reflective particles and higher aerosol light scattering coefficient but summer AAE is only weakly anti-correlated with organic and sulfate mass concentrations. Winter AAE is consistent with a mixture of elemental carbon and light-absorbing organic carbon, possibly influenced by regional residential wood-burning during winter. The hygroscopic dependence of visible light scattering is sensitive to sulfate and organic aerosol mass fractions during both summer and winter

  4. 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

  5. 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.

  6. The Statistical Evolution of Multiple Generations of Oxidation Products in the Photochemical Aging of Chemically Reduced Organic Aerosol

    SciTech Connect

    Wilson, Kevin R.; Smith, Jared D.; Kessler, Sean; Kroll, Jesse H.

    2011-10-03

    The heterogeneous reaction of hydroxyl radicals (OH) with squalane and bis(2-ethylhexyl) sebacate (BES) particles are used as model systems to examine how distributions of reactionproducts evolve during the oxidation of chemically reduced organic aerosol. A kinetic model of multigenerational chemistry, which is compared to previously measured (squalane) and new(BES) experimental data, reveals that it is the statistical mixtures of different generations of oxidation products that control the average particle mass and elemental composition during thereaction. The model suggests that more highly oxidized reaction products, although initially formed with low probability, play a large role in the production of gas phase reaction products.In general, these results highlight the importance of considering atmospheric oxidation as a statistical process, further suggesting that the underlying distribution of molecules could playimportant roles in aerosol formation as well as in the evolution of key physicochemical properties such as volatility and hygroscopicity.

  7. Aerosols formed from the chemical reaction of monoterpenes and ozone

    NASA Astrophysics Data System (ADS)

    Yokouchi, Y.; Ambe, Y.

    Chamber experiments were conducted to study the aerosol products from the ozonolysis of the major atmospheric monoterpenes; α-pinene, β-pinene and limonene. It was found that the α-pinene-O 3 reaction produced mainly 2', 2'-dimethyl-3'-acetyl cyclobutyl ethanal (pinonaldehyde), the β-pinene-O 3 reaction, mainly 6,6-dimethyl-bicyclo [3.1.1] heptan-2-one and the limonene-O 3 reaction, several unidentified products. These products were sought in forest aerosols and pinonaldehyde was detected in the atmosphere.

  8. Aerosols formed from the chemical reaction of monoterpenes and ozone

    NASA Astrophysics Data System (ADS)

    Yokouchi, Y.; Ambe, Y.

    Chamber experiments were conducted to study the aerosol products from the ozonolysis of the major atmospheric monoterpenes; α-pinene, β-pinene and limonene. It was found that the α-pinend-O 3 reaction produced mainly 2'. 2'-dimethyl-3'-acetyl cyclobutyl ethanal (pinonaldehyde), the β-pinene-O 3 reaction, mainly 6,6-dimethyl-bicyclo [3.1.1] heptan-2-one and the limonene-O 3 reaction, several unidentified products. These products were sought in forest aerosols and pinonaldehyde was detected in the atmosphere.

  9. Optical and chemical properties of aerosols transported to Mount Bachelor during spring 2010

    NASA Astrophysics Data System (ADS)

    Fischer, E. V.; Perry, K. D.; Jaffe, D. A.

    2011-09-01

    We report on springtime 2010 observations of aerosol optical properties and size-resolved elemental composition from Mount Bachelor Observatory (MBO; 2763 meters above sea level). Observations included multiwavelength aerosol scattering and absorption, made with a nephelometer and a particle soot absorption photometer, and size-resolved composition, made using a rotating DRUM impactor with substrates analyzed by synchrotron X-ray fluorescence. Our main tool for investigating variability in composition was empirical orthogonal function (EOF) analysis. In April, dust and sulfate explained 96% of the variance in the observed fine composition and accounted for the majority of the fine mode scattering. Three coincident Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation overpasses also identified aerosol layers classified as dust or polluted dust over MBO. Later in the spring, we deduce that organics and nitrate comprised more than 50% of the submicrometer aerosol mass. We used the EOF analysis to identify systematic relationships between composition and optical properties. We observed dust accompanied by anthropogenic pollutants including sulfate. When present, dust aerosol controlled ˜30% of the variability in the wavelength dependence of fine mode scattering. Many of the samples containing sulfate had absorption Ångstrom exponents near 1, suggesting black carbon was also present. Most of the sulfate was in the fine mode, but sulfate was also observed on coarse aerosols, and we inferred that much of the coarse sulfur was coated on the dust or had formed CaSO4 during transport. The relationships between Fe, Ca, Al, and Si observed at MBO were consistent with previous observations of Asian dust transported to North America.

  10. Global Chemical Composition of Ambient Fine Particulate Matter for Exposure Assessment

    PubMed Central

    2015-01-01

    Epidemiologic and health impact studies are inhibited by the paucity of global, long-term measurements of the chemical composition of fine particulate matter. We inferred PM2.5 chemical composition at 0.1° × 0.1° spatial resolution for 2004–2008 by combining aerosol optical depth retrieved from the MODIS and MISR satellite instruments, with coincident profile and composition information from the GEOS-Chem global chemical transport model. Evaluation of the satellite-model PM2.5 composition data set with North American in situ measurements indicated significant spatial agreement for secondary inorganic aerosol, particulate organic mass, black carbon, mineral dust, and sea salt. We found that global population-weighted PM2.5 concentrations were dominated by particulate organic mass (11.9 ± 7.3 μg/m3), secondary inorganic aerosol (11.1 ± 5.0 μg/m3), and mineral dust (11.1 ± 7.9 μg/m3). Secondary inorganic PM2.5 concentrations exceeded 30 μg/m3 over East China. Sensitivity simulations suggested that population-weighted ambient PM2.5 from biofuel burning (11 μg/m3) could be almost as large as from fossil fuel combustion sources (17 μg/m3). These estimates offer information about global population exposure to the chemical components and sources of PM2.5. PMID:25343705

  11. Global Chemical Composition of Ambient Fine Particulate Matter for Exposure Assessment

    DOE PAGES

    Philip, Sajeev; Martin, Randall V.; van Donkelaar, Aaron; ...

    2014-10-24

    Epidemiologic and health impact studies are inhibited by the paucity of global, long-term measurements of the chemical composition of fine particulate matter. We inferred PM2.5 chemical composition at 0.1° × 0.1° spatial resolution for 2004–2008 by combining aerosol optical depth retrieved from the MODIS and MISR satellite instruments, with coincident profile and composition information from the GEOS-Chem global chemical transport model. Evaluation of the satellite-model PM2.5 composition data set with North American in situ measurements indicated significant spatial agreement for secondary inorganic aerosol, particulate organic mass, black carbon, mineral dust, and sea salt. We found that global population-weighted PM2.5 concentrationsmore » were dominated by particulate organic mass (11.9 ± 7.3 μg/m3), secondary inorganic aerosol (11.1 ± 5.0 μg/m3), and mineral dust (11.1 ± 7.9 μg/m3). Secondary inorganic PM2.5 concentrations exceeded 30 μg/m3 over East China. Sensitivity simulations suggested that population-weighted ambient PM2.5 from biofuel burning (11 μg/m3) could be almost as large as from fossil fuel combustion sources (17 μg/m3). In conclusion, these estimates offer information about global population exposure to the chemical components and sources of PM2.5.« less

  12. Towards a quasi-complete reconstruction of past atmospheric aerosol load and composition (organic and inorganic) over Europe since 1920 inferred from Alpine ice cores

    NASA Astrophysics Data System (ADS)

    Preunkert, S.; Legrand, M.

    2013-07-01

    Seasonally resolved chemical ice core records available from the Col du Dôme glacier (4250 m elevation, French Alps), are here used to reconstruct past aerosol load and composition of the free European troposphere from before World War II to present. Available ice core records include inorganic (Na+, Ca2+, NH4+, Cl-, NO3-, and SO42-) and organic (carboxylates, HCHO, humic-like substances, dissolved organic carbon, water-insoluble organic carbon, and black carbon) compounds and fractions that permit reconstructing the key aerosol components and their changes over the past. It is shown that the atmospheric load of submicron aerosol has been increased by a factor of 3 from the 1921-1951 to 1971-1988 years, mainly as a result of a large increase of sulfate (a factor of 5), ammonium and water-soluble organic aerosol (a factor of 3). Thus, not only growing anthropogenic emissions of sulfur dioxide and ammonia have caused the enhancement of the atmospheric aerosol load but also biogenic emissions producing water-soluble organic aerosol. This unexpected change of biospheric source of organic aerosol after 1950 needs to be considered and further investigated in scenarios dealing with climate forcing by atmospheric aerosol.

  13. Towards a quasi-complete reconstruction of past atmospheric aerosol load and composition (organic and inorganic) over Europe since 1920 inferred from Alpine ice cores

    NASA Astrophysics Data System (ADS)

    Preunkert, S.; Legrand, M.

    2013-02-01

    Seasonally resolved chemical ice core records available from the Col du Dôme glacier (4250 m elevation, French Alps) are here revisited in view to reconstruct past aerosol load of the free European troposphere from prior World War II to present. The extended array of inorganic (Na+, Ca2+, NH4+, Cl-, NO3-, and SO42-) and organic (carboxylates, HCHO, HUmic LIke Substances, dissolved organic carbon, water insoluble organic carbon, and black carbon) compounds and fractions already investigated permit to examine the overall aerosol composition and its change over the past. It is shown that the atmospheric load of submicron aerosol has been increased by a factor of 3 from the 1921-1951 to 1971-1988 years, mainly as a result of a large increase of sulfate (a factor of 5), ammonium and water-soluble organic aerosol (a factor of 3). It is shown that not only growing anthropogenic emissions of sulfur dioxide and ammonia have caused the enhancement of the atmospheric aerosol load but also biogenic emissions producing water soluble organic aerosol. This unexpected change of biospheric source of organic aerosol after 1950 needs to be considered and further investigated in scenarii dealing with climate forcing by atmospheric aerosol.

  14. Cloud Condensation Nuclei Activity Associated with Chemical Composition and Precipitation Events

    NASA Astrophysics Data System (ADS)

    Corrigan, C.; Roberts, G. C.; Zauscher, M.; Suski, K.; Noblitts, S.; Sullivan, A. P.; Collett, J. L.

    2010-12-01

    Measurements of ambient cloud condensation nuclei (CCN) concentrations can be improved by simultaneously collecting information on the activation size of the CCN along with chemical composition of the ambient aerosol. A size scanning CCN instrument developed at Scripps Institution of Oceanography was deployed as part of the Calwater project in the Sierra Nevada foothills of California during February and March of 2010. The instrument was capable of determining the critical diameter of activation for the ambient aerosol during a 20 minute scan. During the study period, the CCN activation size increased after each rain event and the activity slowly returned over the next few days. The critical diameter of the overall aerosol was largest (least active) immediately following precipitation events. The average critical diameter would typically decrease by 20% in the time between major precipitation events. This regeneration of the CCN activity can be partially attributed to the transport of sulfate and nitrate pollution to replace the particles that were washed out by the rain, but it may also be due to chemical changes via aging and oxidation mechanisms. Since CCN activity is determined by the particles size and chemical composition, the changes in critical diameter indicate a change in the chemical composition of the available CCN particles. By comparing the critical diameters with aerosol chemical data from a semi-real time aerosol ion chromatograph, the CCN activity was generally correlated with the mass loading of sulfate and nitrate. Deviations from the expected activity of sulfate and nitrate indicate the existence of other compounds that contribute to activity through additional dissolution and by reducing the surface tension. The contribution to CCN activity from additional compounds, including organic surfactants, can be estimated by observing the deviation of the measured critical diameters from values calculated using only the measured nitrate+sulfate mass

  15. Chemical composition of Martian fines

    NASA Technical Reports Server (NTRS)

    Clark, B. C.; Baird, A. K.; Weldon, R. J.; Tsusaki, D. M.; Schnabel, L.; Candelaria, M. P.

    1982-01-01

    Of the 21 samples acquired for the Viking X-ray fluorescence spectrometer, 17 were analyzed to high precision. Compared to typical terrestrial continental soils and lunar mare fines, the Martian fines are lower in Al, higher in Fe, and much higher in S and Cl concentrations. Protected fines at the two lander sites are almost indistinguishable, but concentration of the element S is somewhat higher at Utopia. Duricrust fragments, successfully acquired only at the Chryse site, invariably contained about 50% higher S than fines. No elements correlate positively with S, except Cl and possibly Mg. A sympathetic variation is found among the triad Si, Al, Ca; positive correlation occurs between Ti and Fe. Sample variabilities are as great within a few meters as between lander locations (4500 km apart), implying the existence of a universal Martian regolith component of constant average composition. The nature of the source materials for the regolith fines must be mafic to ultramafic.

  16. 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.

  17. Evaluation of Napped Fabrics for Aerosolized Chemical Agent Protection

    DTIC Science & Technology

    1992-01-30

    agents. Based on laboratory testing, napping had little or no effect on the filtration efficiency, physical or insulation properties of the fabrics tested...0.0 ... 0. . 13 VI. RHsical Properties - Fabric . ........................ 15 VII. Physical Properties - Fabric E...material’ s thermal insulation and physical properties. Small scale liquid aerosol fabric swatch testing for filtration efficiency data was conducted on

  18. The chemical and disperse composition of atmospheric aerosol in different layers of the troposphere background area of south of Western Siberia and its seasonal features on result of airborne sounding by Tupolev-134 "Optik"

    NASA Astrophysics Data System (ADS)

    Belan, Boris D.; Rasskazchikova, Tatyana M.; Simonenkov, Denis V.; Tolmachev, Gennadii N.

    2015-11-01

    This paper presents the data of the vertical distribution of ion concentrations in aerosols and their seasonal characteristics obtained during the flights of the aircraft-laboratory Tupolev-134 "Optics" in 2011 - 2013 over the Karakan boron area in the southern part of the right bank of the Novosibirsk reservoir. The time duration of each flight is about 2 hours. Sampling on Petryanov filters AFA-CP-20 at heights and in the layers of 7000-5500, 4000-3000, 2000-1500 and 1000- 500 meters.

  19. Changes in the concentration and composition of anthropogenic and biogenic aerosols in the Finnish Arctic

    NASA Astrophysics Data System (ADS)

    Yli-Tuomi, Tarja

    In this study, historical samples of Arctic haze collected between 1964 and 1978 from northern Finland have been analyzed. The aim has been to determine the sources of the particles, as well as the temporal variation in the source contributions and the source regions. There is no other long-term data available from this early time period and overall, more information about the occurrence, nature, origin and transport of anthropogenic and biogenic aerosols in the European Arctic is needed in order to protect the vulnerable Arctic environment. In addition, evidence for climate/biosphere interaction observed in a previous study of the Arctic aerosol has been sought. The chemical composition data was analyzed with a Multilinear Engine using two different models, pure bilinear and a mixed 2-way/3-way model. The results of receptor modeling were connected with back trajectory data in a Potential Source Contribution Function analysis to determine the likely source areas. Nine sources, namely silver emissions, coal combustion, biomass burning, nonferrous smelters (two sources), crustal elements from remote sources, excess silicon from local sources, sea salt particles and biogenic sulfur emissions from marine algae were found. Although the emissions from industrial areas in the Kola Peninsula have an effect on the concentration of anthropogenic pollutants at Kevo, the highest concentrations during winter are transported from the sources in the mid-latitudes. The yearly strength of the biogenic sulfur emissions showed no dependence on the Northern Hemisphere temperature anomaly and thus, a climatic feedback loop can not be confirmed.

  20. Determination of aerosol ammonium using an aerodyne aerosol mass spectrometer

    NASA Astrophysics Data System (ADS)

    Delia, A. E.; Toohey, D. W.; Worsnop, D. R.

    2003-04-01

    The chemical composition of fine aerosols is a significant issue both because it influences the chemical and radiative properties of the aerosols, which in turn impact the regional and global climate and human health, and because it is difficult to measure accurately. The Aerosol Mass Spectrometer (AMS) developed by Aerodyne Research measures both chemical composition and aerodynamic size of submicron aerosols quantitatively. However, the measurement of aerosol ammonium is more difficult than that of the other major inorganic species, nitrate and sulfate, because of interferences in the mass spectrum from air and water. This presentation will describe the successful procedure developed for dealing with these interferences and accurately determining the ammonium mass. In addition, the application of this procedure to aerosols from a range of ambient conditions will be demonstrated using data from several field studies.

  1. Probing the impact of different aerosol sources on cloud microphysics and precipitation through in-situ measurements of chemical mixing state

    NASA Astrophysics Data System (ADS)

    Prather, K. A.; Suski, K.; Cazorla, A.; Cahill, J. F.; Creamean, J.; Collins, D. B.; Heymsfield, A.; Roberts, G. C.; DeMott, P. J.; Sullivan, R. C.; Rosenfeld, D.; Comstock, J. M.; Tomlinson, J. M.

    2011-12-01

    Aerosol particles play a crucial role in affecting cloud processes by serving as cloud nuclei. However, our understanding of which particles actually form cloud and ice nuclei limits our ability to treat aerosols properly in climate models. In recent years, it has become possible to measure the chemical composition of individual cloud nuclei within the clouds using on-line mass spectrometry. In-situ high time resolution chemistry can now be compared with cloud physics measurements to directly probe the impact of aerosol chemistry on cloud microphysics. This presentation will describe results from two recent field campaigns, CalWater in northern California and ICE-T in the western Caribbean region. Ground-based and aircraft measurements will be presented of aerosol mixing state, cloud microphysics, and meteorology. Results from single particle mass spectrometry will show the sources of the cloud seeds, including dust, biomass burning, sea spray, and biological particles. Details will be provided on how we are now able to probe the sources and cycling of atmospheric aerosols by measuring individual aerosols, cloud nuclei, and precipitation chemistry. The important role of dust, both Asian and African, and bioparticles in forming ice nuclei will be discussed. Finally, a summary will be provided discussing how these new in-situ measurements are being used to advance our understanding of complex atmospheric processes, and improve our understanding of aerosol impacts on climate.

  2. 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.

  3. Triple Isotopic Composition of Atmospheric Carbonates: A Novel Technique to Identify Heterogeneous Chemistry on Aerosol Surfaces in Polluted Environment

    NASA Astrophysics Data System (ADS)

    Shaheen, R.; Horn, J.; Dominguez, G.; Masterson, A.; Ivanov, A. V.; Thiemens, M. H.

    2009-12-01

    In the ambient atmosphere, the physical and chemical properties of aerosol vary greatly between location and time due to various heterogeneous and photochemical reactions in the atmosphere. In polluted urban environments, the aerosol and gaseous mixtures interact to produce new compounds and particulates; consequently humans are exposed to many as yet undetected species. Studies of actual chemically-active, airborne particulates can better address the interaction of complex particulate and gaseous pollutant mixtures, however, it is notoriously difficult to measure chemical transformations of aerosols. Here we describe a new technique that can be used to understand the chemical transformation occurring on the surface of aerosols and thus to quantify the interaction of gaseous species and aerosol in the atmosphere. Fine and coarse aerosol samples were collected on filter papers in La Jolla, CA, USA for one week. The aerosol samples were digested with phosphoric acid and CO2 released was purified chromatographically and analyzed for 13 C. To obtain independent measurements of oxygen isotopes, the CO2 was fluorinated and oxygen gas obtained was analyzed using Mat253 Isotope Ratio Mass Spectrometer. The data indicated an excess 17O (0.6 to 4‰) in atmospheric carbonates. The oxygen isotope anomaly in atmospheric carbonates has been observed for the first time and it showed a highly significant correlation (r2 = 0.90) with urban index; an indirect measure of ozone chemistry. The δ13C in atmospheric carbonates was found to vary from -18 to -40‰. Controlled laboratory experiments to understand the origin and variation in the C and O isotopic composition of atmospheric carbonates were conducted using various mineral surfaces. Isotopic measurements of in-situ formed carbonated on CaOH, CaO, MgO, SiO2,Cu, CuO, Ni and Fe2O3 due to chemisorbed CO2 in the presence of thin water films were performed and we found that the δ13C in these carbonates ranged from -12 to -24

  4. Two chemically distinct light-absorbing pools of urban organic aerosols: A comprehensive multidimensional analysis of trends.

    PubMed

    Paula, Andreia S; Matos, João T V; Duarte, Regina M B O; Duarte, Armando C

    2016-02-01

    The chemical and light-absorption dynamics of organic aerosols (OAs), a master variable in the atmosphere, have yet to be resolved. This study uses a comprehensive multidimensional analysis approach for exploiting simultaneously the compositional changes over a molecular size continuum and associated light-absorption (ultraviolet absorbance and fluorescence) properties of two chemically distinct pools of urban OAs chromophores. Up to 45% of aerosol organic carbon (OC) is soluble in water and consists of a complex mixture of fluorescent and UV-absorbing constituents, with diverse relative abundances, hydrophobic, and molecular weight (Mw) characteristics between warm and cold periods. In contrast, the refractory alkaline-soluble OC pool (up to 18%) is represented along a similar Mw and light-absorption continuum throughout the different seasons. Results suggest that these alkaline-soluble chromophores may actually originate from primary OAs sources in the urban site. This work shows that the comprehensive multidimensional analysis method is a powerful and complementary tool for the characterization of OAs fractions. The great diversity in the chemical composition and optical properties of OAs chromophores, including both water-soluble and alkaline-soluble OC, may be an important contribution to explain the contrasting photo-reactivity and atmospheric behavior of OAs.

  5. Binary stars: Mass transfer and chemical composition

    NASA Technical Reports Server (NTRS)

    Lambert, D. L.

    1982-01-01

    It is noted that mass exchange (and mass loss) within a binary system should produce observable changes in the surface chemical composition of both the mass losing and mass gaining stars as a stellar interior exposed to nucleosyntheses is uncovered. Three topics relating mass exchange and/or mass loss to nucleosynthesis are sketched: the chemical composition of Algol systems; the accretion disk of a cataclysmic variable fed by mass from a dwarf secondary star; and the hypothesis that classical Ba II giants result from mass transfer from a more evolved companion now present as a white dwarf.

  6. Aerosol physical and chemical properties retrieved from ground-based remote sensing measurements during heavy haze days in Beijing winter

    NASA Astrophysics Data System (ADS)

    Li, Z.; Gu, X.; Wang, L.; Li, D.; Xie, Y.; Li, K.; Dubovik, O.; Schuster, G.; Goloub, P.; Zhang, Y.; Li, L.; Ma, Y.; Xu, H.

    2013-10-01

    With the increase in economic development over the past thirty years, many large cities in eastern and southwestern China are experiencing increased haze events and atmospheric pollution, causing significant impacts on the regional environment and even climate. However, knowledge on the aerosol physical and chemical properties in heavy haze conditions is still insufficient. In this study, two winter heavy haze events in Beijing that occurred in 2011 and 2012 were selected and investigated by using the ground-based remote sensing measurements. We used a CIMEL CE318 sun-sky radiometer to retrieve haze aerosol optical, physical and chemical properties, including aerosol optical depth (AOD), size distribution, complex refractive indices and aerosol fractions identified as black carbon (BC), brown carbon (BrC), mineral dust (DU), ammonium sulfate-like (AS) components and aerosol water content (AW). The retrieval results from a total of five haze days showed that the aerosol loading and properties during the two winter haze events were comparable. Therefore, average heavy haze property parameters were drawn to present a research case for future studies. The average AOD is about 3.0 at 440 nm, and the Ångström exponent is 1.3 from 440 to 870 nm. The fine-mode AOD is 2.8 corresponding to a fine-mode fraction of 0.93. The coarse particles occupied a considerable volume fraction of the bimodal size distribution in winter haze events, with the mean particle radius of 0.21 and 2.9 μm for the fine and coarse modes respectively. The real part of the refractive indices exhibited a relatively flat spectral behavior with an average value of 1.48 from 440 to 1020 nm. The imaginary part showed spectral variation, with the value at 440 nm (about 0.013) higher than the other three wavelengths (about 0.008 at 675 nm). The aerosol composition retrieval results showed that volume fractions of BC, BrC, DU, AS and AW are 1, 2, 49, 15 and 33%, respectively, on average for the investigated

  7. Evidence for ships emissions in the Central Mediterranean Sea from aerosol chemical analyses at the island of Lampedusa

    NASA Astrophysics Data System (ADS)

    Becagli, S.; Sferlazzo, D. M.; Pace, G.; di Sarra, A.; Bommarito, C.; Calzolai, G.; Ghedini, C.; Lucarelli, F.; Meloni, D.; Monteleone, F.; Severi, M.; Traversi, R.; Udisti, R.

    2011-11-01

    Measurements of aerosol chemical composition made on the island of Lampedusa, south of the Sicily channel, during years 2004-2008, are used to identify the influence of ship emissions on aerosol particles in the Central Mediterranean. Evidence of ship emissions influence is found in 17% of the daily samples. Aerosol samples influenced by ships are characterized by elevated Ni and V soluble fraction (about 80% for aerosol from ships, versus about 40 % for crustal particles), high V and Ni to Si ratios, and values of Vsol>6 ng m-3. Back trajectories analysis on the selected events show that air masses prevalently come from the Sicily channel, where an intense ship traffic occurs. Vsol, Nisol, and non-sea salt SO42- (nssSO42-) show a marked seasonal behaviour, with an evident summer maximum. Such a pattern can be explained by several processes: (i) increased photochemical activity in summer, leading to a faster production of secondary aerosols, mainly nssSO42-, from the oxidation of SO2 in the ship plume; (ii) stronger marine boundary layer (MBL) stability in summer, leading to higher concentration of emitted compounds in the lowest atmospheric layers; (iii) more frequent meteorological conditions leading to consecutive days with trajectories from the Sicily channel in summer. A very intense event in spring 2008 was studied in detail, also using size segregated chemical measurements. These data show that elements arising from heavy oil combustion (V, Ni, Al, Fe) are distributed in the sub-micrometric fraction of the aerosol, and the metals are present as free metals, carbonates, oxides hydrates or labile complex with organic ligands, so that they are dissolved in mild condition (HNO3, pH1.5). Data suggest a characteristic nssSO42-/V ratio in the range 200-400 for ship emission aerosols in summer at Lampedusa. By using the value of 200 a lower limit for the ship contribution to total sulphates is estimated. Ship emissions account, as a summer average, at least for 1

  8. Atmospheric Black Carbon: Chemical Bonding and Structural Information of Individual Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Gilles, M. K.; Tivanski, A. V.; Hopkins, R. J.; Marten, B. D.

    2006-12-01

    The formation of aerosols from both natural and anthropogenic sources affects the Earth's temperature and climate by altering the radiative properties of the atmosphere. Aerosols containing black carbon (BC) that are released into the atmosphere from the burning of biomass, natural fires and the combustion of coals, diesel and jet fuels, contribute a large positive component to this radiative forcing, thus causing a heating of the atmosphere. A distinct type of biomass burn aerosol referred to as "tar balls" has recently been reported in the literature and is characterized by a spherical morphology, high carbon content and ability to efficiently scatter and absorb light. At present, very little is known about the exact nature and variation of the range of BC aerosols in the atmosphere with regards to optical, chemical and physical properties. Additionally, the similarity of these aerosols to surrogates used in the laboratory as atmospheric mimics remains unclear. The local chemical bonding, structural ordering and carbon-to-oxygen ratios of a plethora of black carbon standard reference materials (BC SRMs), high molecular mass humic-like substances (HULIS) and atmospheric aerosols from a variety of sources are examined using scanning transmission X-ray microscopy (STXM) coupled with near edge X-ray absorption fine structure (NEXAFS) spectroscopy. STXM/NEXAFS enables single aerosol particles of diameter upwards of 100 nm to be studied, which allows the diversity of atmospheric aerosol collected during a variety of field missions to be assessed. We apply a semi-quantitative peak fitting method to the recorded NEXAFS spectral fingerprints allowing comparison of BC SRMs and HULIS to BC aerosol originating from anthropogenic combustion and biomass burning events. This method allows us to distinguish between anthropogenic combustion and biomass burn aerosol using both chemical bonding and structural ordering information. The STXM/NEXAFS technique has also been utilized to

  9. Monitoring and tracking the trans-Pacific transport of aerosols using multi-satellite aerosol optical depth composites

    NASA Astrophysics Data System (ADS)

    Naeger, Aaron R.; Gupta, Pawan; Zavodsky, Bradley T.; McGrath, Kevin M.

    2016-06-01

    The primary goal of this study was to generate a near-real time (NRT) aerosol optical depth (AOD) product capable of providing a comprehensive understanding of the aerosol spatial distribution over the Pacific Ocean, in order to better monitor and track the trans-Pacific transport of aerosols. Therefore, we developed a NRT product that takes advantage of observations from both low-earth orbiting and geostationary satellites. In particular, we utilize AOD products from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Suomi National Polar-orbiting Partnership (NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) satellites. Then, we combine these AOD products with our own retrieval algorithms developed for the NOAA Geostationary Operational Environmental Satellite (GOES-15) and Japan Meteorological Agency (JMA) Multi-functional Transport Satellite (MTSAT-2) to generate a NRT daily AOD composite product. We present examples of the daily AOD composite product for a case study of trans-Pacific transport of Asian pollution and dust aerosols in mid-March 2014. Overall, the new product successfully tracks this aerosol plume during its trans-Pacific transport to the west coast of North America as the frequent geostationary observations lead to a greater coverage of cloud-free AOD retrievals equatorward of about 35° N, while the polar-orbiting satellites provide a greater coverage of AOD poleward of 35° N. However, we note several areas across the domain of interest from Asia to North America where the GOES-15 and MTSAT-2 retrieval algorithms can introduce significant uncertainties into the new product.

  10. Filter measurements of chemical composition during the airborne Antarctic ozone experiment

    NASA Technical Reports Server (NTRS)

    Grandrud, B. W.; Sperry, P. D.; Sanford, L.

    1988-01-01

    During the Airborne Antarctic Ozone Experiment campaign, a filter sampler was flown to measure the bulk composition of aerosol and gas phases. The background sulfate aerosol was measured in regions inside and outside of the chemically perturbed region (CPR) of the polar vortex. The mass ratio of sulfate outside to inside was 2.8. This is indicative of a cleansing mechanism effecting the CPR or of a different air mass inside versus outside. The absolute value of the sulfate mixing ratio shows that the background aerosol has not been influenced by recent volcanic eruptions. The sulfate measured on the ferry flight returning to NASA Ames shows a decrease towards the equator with increasing concentrations in the northern hemisphere. Nitrate in the aerosol phase was observed on two flights. The largest amount of nitrate measured in the aerosol was 44 percent of the total amount of nitrate observed. Other samples on the same flights show no nitrate in the aerosol phase. The presence of nitrate in the aerosol is correlated with the coldest temperatures observed on a given flight. Total nitrate (aerosol plus acidic vapor nitrate) concentrations were observed to increase at flight altitude with increasing latitude north and south of the equator. Total nitrate was lower inside the CPR than outside. Chloride and flouride were not detected in the aerosol phase. From the concentrations of acidic chloride vapor, the ratio of acidic vapor Cl to acidic vapor F and a summing of the individual chloride containing species to yield a total chloride concentration, there is a suggestion that some of the air sampled was dechlorinated. Acidic vapor phase fluoride was observed to increase at flight altitude with increasing latitude both north and south of the equator. The acidic vapor phase fluoride was the only compound measured with the filter technique that exhibited larger concentrations inside the CPR than outside.

  11. Chemical aging of single and multicomponent biomass burning aerosol surrogate particles by OH: implications for cloud condensation nucleus activity

    NASA Astrophysics Data System (ADS)

    Slade, J. H.; Thalman, R.; Wang, J.; Knopf, D. A.

    2015-09-01

    Multiphase OH and O3 oxidation reactions with atmospheric organic aerosol (OA) can influence particle physicochemical properties including composition, morphology, and lifetime. Chemical aging of initially insoluble or low-soluble single-component OA by OH and O3 can increase their water solubility and hygroscopicity, making them more active as cloud condensation nuclei (CCN) and susceptible to wet deposition. However, an outstanding problem is whether the effects of chemical aging on their CCN activity are preserved when mixed with other organic or inorganic compounds exhibiting greater water solubility. In this work, the CCN activity of laboratory-generated biomass burning aerosol (BBA) surrogate particles exposed to OH and O3 is evaluated by determining the hygroscopicity parameter, κ, as a function of particle type, mixing state, and OH and O3 exposure applying a CCN counter (CCNc) coupled to an aerosol flow reactor (AFR). Levoglucosan (LEV), 4-methyl-5-nitrocatechol (MNC), and potassium sulfate (KS) serve as representative BBA compounds that exhibit different hygroscopicity, water solubility, chemical functionalities, and reactivity with OH radicals, and thus exemplify the complexity of mixed inorganic/organic aerosol in the atmosphere. The CCN activities of all of the particles were unaffected by O3 exposure. Following exposure to OH, κ of MNC was enhanced by an order of magnitude, from 0.009 to ~ 0.1, indicating that chemically aged MNC particles are better CCN and more prone to wet deposition than pure MNC particles. No significant enhancement in κ was observed for pure LEV particles following OH exposure. κ of the internally mixed particles was not affected by OH oxidation. Furthermore, the CCN activity of OH-exposed MNC-coated KS particles is similar to the OH unexposed atomized 1 : 1 by mass MNC : KS binary-component particles. Our results strongly suggest that when OA is dominated by water-soluble organic carbon (WSOC) or inorganic ions, chemical

  12. Chemical aging of single and multicomponent biomass burning aerosol surrogate-particles by OH: implications for cloud condensation nucleus activity

    NASA Astrophysics Data System (ADS)

    Slade, J. H.; Thalman, R.; Wang, J.; Knopf, D. A.

    2015-03-01

    Multiphase OH and O3 oxidation reactions with atmospheric organic aerosol (OA) can influence particle physicochemical properties including composition, morphology, and lifetime. Chemical aging of initially insoluble or low soluble single-component OA by OH and O3 can increase their water-solubility and hygroscopicity, making them more active as cloud condensation nuclei (CCN) and susceptible to wet deposition. However, an outstanding problem is whether the effects of chemical aging on their CCN activity are preserved when mixed with other organic or inorganic compounds exhibiting greater water-solubility. In this work, the CCN activity of laboratory-generated biomass burning aerosol (BBA) surrogate-particles exposed to OH and O3 is evaluated by determining the hygroscopicity parameter, κ, as a function of particle type, mixing state, and OH/O3 exposure applying a CCN counter (CCNc) coupled to an aerosol flow reactor (AFR). Levoglucosan (LEV), 4-methyl-5-nitrocatechol (MNC), and potassium sulfate (KS) serve as representative BBA compounds that exhibit different hygroscopicity, water solubility, chemical functionalities, and reactivity with OH radicals, and thus exemplify the complexity of mixed inorganic/organic aerosol in the atmosphere. The CCN activities of all of the particles were unaffected by O3 exposure. Following exposure to OH, κ of MNC was enhanced by an order of magnitude, from 0.009 to ~0.1, indicating that chemically-aged MNC particles are better CCN and more prone to wet deposition than pure MNC particles. No significant enhancement in κ was observed for pure LEV particles following OH exposure. κ of the internally-mixed particles was not affected by OH oxidation. Furthermore, the CCN activity of OH exposed MNC-coated KS particles is similar to the OH unexposed atomized 1 : 1 by mass MNC : KS binary-component particles. Our results strongly suggest that when OA is dominated by water-soluble organic carbon (WSOC) or inorganic ions, chemical aging

  13. Chemical aging of single and multicomponent biomass burning aerosol surrogate-particles by OH: Implications for cloud condensation nucleus activity

    DOE PAGES

    Thalman, R.; Thalman, R.; Wang, J.; ...

    2015-03-06

    Multiphase OH and O₃ oxidation reactions with atmospheric organic aerosol (OA) can influence particle physicochemical properties including composition, morphology, and lifetime. Chemical aging of initially insoluble or low soluble single-component OA by OH and O₃ can increase their water-solubility and hygroscopicity, making them more active as cloud condensation nuclei (CCN) and susceptible to wet deposition. However, an outstanding problem is whether the effects of chemical aging on their CCN activity are preserved when mixed with other organic or inorganic compounds exhibiting greater water-solubility. In this work, the CCN activity of laboratory-generated biomass burning aerosol (BBA) surrogate-particles exposed to OH andmore » O₃ is evaluated by determining the hygroscopicity parameter, κ, as a function of particle type, mixing state, and OH/O₃ exposure applying a CCN counter (CCNc) coupled to an aerosol flow reactor (AFR). Levoglucosan (LEV), 4-methyl-5-nitrocatechol (MNC), and potassium sulfate (KS) serve as representative BBA compounds that exhibit different hygroscopicity, water solubility, chemical functionalities, and reactivity with OH radicals, and thus exemplify the complexity of mixed inorganic/organic aerosol in the atmosphere. The CCN activities of all of the particles were unaffected by O₃ exposure. Following exposure to OH, κ of MNC was enhanced by an order of magnitude, from 0.009 to ~0.1, indicating that chemically-aged MNC particles are better CCN and more prone to wet deposition than pure MNC particles. No significant enhancement in κ was observed for pure LEV particles following OH exposure. κ of the internally-mixed particles was not affected by OH oxidation. Furthermore, the CCN activity of OH exposed MNC-coated KS particles is similar to the OH unexposed atomized 1:1 by mass MNC: KS binary-component particles. Our results strongly suggest that when OA is dominated by water-soluble organic carbon (WSOC) or inorganic ions

  14. Chemical aging of single and multicomponent biomass burning aerosol surrogate particles by OH: implications for cloud condensation nucleus activity

    DOE PAGES

    Slade, J. H.; Thalman, R.; Wang, J.; ...

    2015-09-14

    Multiphase OH and O3 oxidation reactions with atmospheric organic aerosol (OA) can influence particle physicochemical properties including composition, morphology, and lifetime. Chemical aging of initially insoluble or low-soluble single-component OA by OH and O3 can increase their water solubility and hygroscopicity, making them more active as cloud condensation nuclei (CCN) and susceptible to wet deposition. However, an outstanding problem is whether the effects of chemical aging on their CCN activity are preserved when mixed with other organic or inorganic compounds exhibiting greater water solubility. In this work, the CCN activity of laboratory-generated biomass burning aerosol (BBA) surrogate particles exposed tomore » OH and O3 is evaluated by determining the hygroscopicity parameter, κ, as a function of particle type, mixing state, and OH and O3 exposure applying a CCN counter (CCNc) coupled to an aerosol flow reactor (AFR). Levoglucosan (LEV), 4-methyl-5-nitrocatechol (MNC), and potassium sulfate (KS) serve as representative BBA compounds that exhibit different hygroscopicity, water solubility, chemical functionalities, and reactivity with OH radicals, and thus exemplify the complexity of mixed inorganic/organic aerosol in the atmosphere. The CCN activities of all of the particles were unaffected by O3 exposure. Following exposure to OH, κ of MNC was enhanced by an order of magnitude, from 0.009 to ~ 0.1, indicating that chemically aged MNC particles are better CCN and more prone to wet deposition than pure MNC particles. No significant enhancement in κ was observed for pure LEV particles following OH exposure. κ of the internally mixed particles was not affected by OH oxidation. Furthermore, the CCN activity of OH-exposed MNC-coated KS particles is similar to the OH unexposed atomized 1 : 1 by mass MNC : KS binary-component particles. Our results strongly suggest that when OA is dominated by water-soluble organic carbon (WSOC) or inorganic ions

  15. Chemical aging of single and multicomponent biomass burning aerosol surrogate-particles by OH: Implications for cloud condensation nucleus activity

    SciTech Connect

    Thalman, R.; Thalman, R.; Wang, J.; Knopf, D. A.

    2015-03-06

    Multiphase OH and O₃ oxidation reactions with atmospheric organic aerosol (OA) can influence particle physicochemical properties including composition, morphology, and lifetime. Chemical aging of initially insoluble or low soluble single-component OA by OH and O₃ can increase their water-solubility and hygroscopicity, making them more active as cloud condensation nuclei (CCN) and susceptible to wet deposition. However, an outstanding problem is whether the effects of chemical aging on their CCN activity are preserved when mixed with other organic or inorganic compounds exhibiting greater water-solubility. In this work, the CCN activity of laboratory-generated biomass burning aerosol (BBA) surrogate-particles exposed to OH and O₃ is evaluated by determining the hygroscopicity parameter, κ, as a function of particle type, mixing state, and OH/O₃ exposure applying a CCN counter (CCNc) coupled to an aerosol flow reactor (AFR). Levoglucosan (LEV), 4-methyl-5-nitrocatechol (MNC), and potassium sulfate (KS) serve as representative BBA compounds that exhibit different hygroscopicity, water solubility, chemical functionalities, and reactivity with OH radicals, and thus exemplify the complexity of mixed inorganic/organic aerosol in the atmosphere. The CCN activities of all of the particles were unaffected by O₃ exposure. Following exposure to OH, κ of MNC was enhanced by an order of magnitude, from 0.009 to ~0.1, indicating that chemically-aged MNC particles are better CCN and more prone to wet deposition than pure MNC particles. No significant enhancement in κ was observed for pure LEV particles following OH exposure. κ of the internally-mixed particles was not affected by OH oxidation. Furthermore, the CCN activity of OH exposed MNC-coated KS particles is similar to the OH unexposed atomized 1:1 by mass MNC: KS binary-component particles. Our results strongly suggest that when OA is dominated by water-soluble organic carbon (WSOC) or inorganic ions, chemical

  16. Insights into the molecular level composition, sources, and formation mechanisms of dissolved organic matter in aerosols and precipitation

    NASA Astrophysics Data System (ADS)

    Altieri, Katye Elisabeth

    Atmospheric aerosols scatter and absorb light influencing the global radiation budget and climate, and are associated with adverse effects on human health. Precipitation is an important removal mechanism for atmospheric dissolved organic matter (DOM), and a potentially important input for receiving ecosystems. However, the sources, formation, and composition of atmospheric DOM in aerosols and precipitation are not well understood. This dissertation investigates the composition and formation mechanisms of secondary organic aerosol (SOA) formed through cloud processing reactions, elucidates the composition and sources of DOM in rainwater, and provides links connecting the two. Photochemical batch aqueous-phase reactions of organics with both biogenic and anthropogenic sources (i.e., methylglyoxal, pyruvic acid) and OH radical were performed to simulate cloud processing. The composition of products formed through cloud processing experiments and rainwater collected in New Jersey, USA was investigated using a combination of electrospray ionization mass spectrometry techniques, including ultra-high resolution Fourier transform ion cyclotron resonance mass spectrometry. This dissertation has resulted in the first evidence that oligomers form through cloud processing reactions, the first detailed chemical mechanism of aqueous phase oligomerization, the first identification of oligomers, organosulfates, and nitrooxy organosulfates in precipitation, and the first molecular level chemical characterization of organic nitrogen in precipitation. The formation of oligomers in SOA helps to explain the presence of large multifunctional compounds and humic like substances (HULIS) that dominate particulate organic mass. Oligomers have low vapor pressures and remain in the particle phase after cloud evaporation, enhancing SOA. The chemical properties of the oligomers suggest that they are less hygroscopic than the monomeric reaction products (i.e., organic acids). Their elemental

  17. Aerosol Phosphorus Composition: New Insights from Synchrotron X-ray Spectroscopy

    NASA Astrophysics Data System (ADS)

    Longo, A.; Ingall, E. D.; Diaz, J. M.; Oakes, M. M.; King, L.; Nenes, A.; Mihalopoulos, N.; Violaki, K.; Avila, A.; Benitez-Nelson, C. R.; Brandes, J. A.; McNulty, I.; Vine, D.

    2014-12-01

    Biological productivity in many ocean regions is controlled by the availability of the nutrient phosphorus (P), including the eastern Mediterranean Sea. Aerosol deposition is a key source of P in the Mediterranean. Understanding the composition of this P is critical for determining its solubility and therefore potential bioavailability. We investigated aerosol P composition in European and North African air masses, the main sources of aerosol deposition to the Mediterranean Sea, using Phosphorus Near Edge X-ray Fluorescence Spectroscopy (P-NEXFS). We show that European aerosols are a significant source of soluble P to the Mediterranean Sea. The traditionally studied North African sourced air masses carry more total P to the Mediterranean Sea than European sourced air masses and contain mostly apatite, a largely insoluble calcium phosphate mineral. However, European aerosols deliver P that is on average 3.5 times more soluble than North African aerosols and furthermore are dominated by organic P compounds. The increased solubility of European aerosols leads to comparable amounts of soluble P by mass delivered to the Mediterranean Sea by both air masses. The ultimate origin of organic P does not stem from common primary emission sources, such as coal fly ash and diesel emissions. Rather, P associated with bacteria best explains the presence of organic P in Mediterranean aerosols. The soluble organic nature of the P in European sourced air masses underscores the need to examine aerosols from this region as a source of P to the Mediterranean Sea. This study also demonstrates that synchrotron-based techniques are effective tools for characterizing aerosols and gaining new insights.

  18. Urban aerosol in Oporto, Portugal: Chemical characterization of PM10 and PM2.5

    NASA Astrophysics Data System (ADS)

    Custódio, Danilo; Ferreira, Catarina; Alves, Célia; Duarte, Mácio; Nunes, Teresa; Cerqueira, Mário; Pio, Casimiro; Frosini, Daniele; Colombi, Cristina; Gianelle, Vorne; Karanasiou, Angeliki; Querol, Xavier

    2014-05-01

    Several urban and industrial areas in Southern Europe are not capable of meeting the implemented EU standards for particulate matter. Efficient air quality management is required in order to ensure that the legal limits are not exceeded and that the consequences of poor air quality are controlled and minimized. Many aspects of the direct and indirect effects of suspended particulate matter on climate and public health are not well understood. The temporal variation of the chemical composition is still demanded, since it enables to adopt off-set strategies and to better estimate the magnitude of anthropogenic forcing on climate. This study aims to provide detailed information on concentrations and chemical composition of aerosol from Oporto city, an urban center in Southern Europe. This city is located near the coast line in the North of Portugal, being the country's second largest urban area. Moreover, Oporto city economic prospects depend heavily on a diversified industrial park, which contribute to air quality degradation. Another strong source of air pollution is traffic. The main objectives of this study are: 1) to characterize the chemical composition of PM10 and PM2.5 by setting up an orchestra of aerosol sampling devices in a strategic place in Oporto; 2) to identify the sources of particles exploring parameters such as organic and inorganic markers (e.g. sugars as tracers for biomass burning; metals and elemental carbon for industrial and vehicular emissions); 3) to evaluate long range transport of pollutants using back trajectory analysis. Here we present data obtained between January 2013 and January 2014 in a heavy traffic roadside sampling site located in the city center. Different PM10 and PM2.5 samplers were operated simultaneously in order to collect enough mass on different filter matrixes and to fulfill the requirements of analytical methodologies. More than 100 aerosol samples were collected and then analysed for their mass concentration and

  19. Water soluble aerosols and gases at a UK background site - Part 1: Controls of PM2.5 and PM10 aerosol composition

    NASA Astrophysics Data System (ADS)

    Twigg, M. M.; Di Marco, C. F.; Leeson, S.; van Dijk, N.; Jones, M. R.; Leith, I. D.; Morrison, E.; Coyle, M.; Proost, R.; Peeters, A. N. M.; Lemon, E.; Frelink, T.; Braban, C. F.; Nemitz, E.; Cape, J. N.

    2015-07-01

    There is limited availability of long-term, high temporal resolution, chemically speciated aerosol measurements which can provide further insight into the health and environmental impacts of particulate matter. The Monitor for AeRosols and Gases (MARGA, Applikon B.V., NL) allows for the characterisation of the inorganic components of PM10 and PM2.5 (NH4+, NO3-, SO42-, Cl-, Na+, K+, Ca2+, Mg2+) and inorganic reactive gases (NH3, SO2, HCl, HONO and HNO3) at hourly resolution. The following study presents 6.5 years (June 2006 to December 2012) of quasi-continuous observations of PM2.5 and PM10 using the MARGA at the UK EMEP supersite, Auchencorth Moss, SE Scotland. Auchencorth Moss was found to be representative of a remote European site with average total water soluble inorganic mass of PM2.5 of 3.82 μg m-3. Anthropogenically derived secondary inorganic aerosols (sum of NH4+, NO3- and nss-SO42-) were the dominating species (63 %) of PM2.5. In terms of equivalent concentrations, NH4+ provided the single largest contribution to PM2.5 fraction in all seasons. Sea salt was the main component (73 %) of the PMcoarse fraction (PM10-PM2.5), though NO3- was also found to make a relatively large contribution to the measured mass (17 %) providing evidence of considerable processing of sea salt in the coarse mode. There was on occasions evidence of aerosol from combustion events being transported to the site in 2012 as high K+ concentrations (deviating from the known ratio in sea salt) coincided with increases in black carbon at the site. Pollution events in PM10 (defined as concentrations > 12 μg m-3) were on average dominated by NH4+ and NO3-, where smaller loadings at the site tended to be dominated by sea salt. As with other western European sites, the charge balance of the inorganic components resolved were biased towards cations, suggesting the aerosol was basic or more likely that organic acids contributed to the charge balance. This study demonstrates the UK

  20. Water soluble aerosols and gases at a UK background site - Part 1: Controls of PM2.5 and PM10 aerosol composition

    NASA Astrophysics Data System (ADS)

    Twigg, M. M.; Di Marco, C. F.; Leeson, S.; van Dijk, N.; Jones, M. R.; Leith, I. D.; Morrison, E.; Coyle, M.; Proost, R.; Peeters, A. N. M.; Lemon, E.; Frelink, T.; Braban, C. F.; Nemitz, E.; Cape, J. N.

    2015-02-01

    There is limited availability of long-term, high temporal resolution, chemically speciated aerosol measurements, which can lead to further insight into the health and environmental impacts of particulate matter. The Monitor for AeRosols and Gases (MARGA, Applikon B.V., NL) allows characterisation of the inorganic components of PM10 and PM2.5 (NH4+, NO3-, SO42-, Cl-, Na+, K+, Ca2+, Mg2+) and inorganic reactive gases (NH3, SO2, HCl, HONO and HNO3) at hourly resolution. The following study presents 6.5 years (June 2006 to December 2012) of quasi-continuous observations of PM2.5 and PM10 using the MARGA at the UK EMEP "Supersite", Auchencorth Moss, SE Scotland. Auchencorth Moss was found to be representative of a remote European site with average total water soluble inorganic mass of PM2.5 of 3.82 μg m-3. Anthropogenically derived secondary inorganic aerosols (sum of NH4+, NO3- and nss-SO42-), were the dominating species (63%) of PM2.5. In terms of equivalent concentrations, NH4+ provided the single largest contribution to PM2.5 fraction in all seasons. Sea salt, was the main component (73%) of the PMcoarse fraction (PM10-PM2.5), though NO3- was also found to make a relatively large contribution to the measured mass (17%) as providing evidence of considerable processing of sea salt in the coarse mode. There was on occasions evidence of aerosol from combustion events being transported to the site in 2012 as high K+ concentrations (deviating from the known ratio in sea salt) coincided with increases in black carbon at the site. Pollution events in PM10 (defined as concentrations > 12 μg m-3) were on average dominated by NH4+ and NO3-, where as smaller loadings at the site tended to be dominated by sea salt. As with other Western European sites, the charge balance of the inorganic components resolved were biased towards cations, suggesting the aerosol was basic or more likely, that organic acids contributed to the charge

  1. The impacts of aerosol loading, composition, and water uptake on aerosol extinction variability in the Baltimore-Washington, D.C. region

    NASA Astrophysics Data System (ADS)

    Beyersdorf, A. J.; Ziemba, L. D.; Chen, G.; Corr, C. A.; Crawford, J. H.; Diskin, G. S.; Moore, R. H.; Thornhill, K. L.; Winstead, E. L.; Anderson, B. E.

    2016-01-01

    In order to utilize satellite-based aerosol measurements for the determination of air quality, the relationship between aerosol optical properties (wavelength-dependent, column-integrated extinction measured by satellites) and mass measurements of aerosol loading (PM2.5 used for air quality monitoring) must be understood. This connection varies with many factors including those specific to the aerosol type - such as composition, size, and hygroscopicity - and to the surrounding atmosphere, such as temperature, relative humidity (RH), and altitude, all of which can vary spatially and temporally. During the DISCOVER-AQ (Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality) project, extensive in situ atmospheric profiling in the Baltimore, MD-Washington, D.C. region was performed during 14 flights in July 2011. Identical flight plans and profile locations throughout the project provide meaningful statistics for determining the variability in and correlations between aerosol loading, composition, optical properties, and meteorological conditions. Measured water-soluble aerosol mass was composed primarily of ammonium sulfate (campaign average of 32 %) and organics (57 %). A distinct difference in composition was observed, with high-loading days having a proportionally larger percentage of sulfate due to transport from the Ohio River Valley. This composition shift caused a change in the aerosol water-uptake potential (hygroscopicity) such that higher relative contributions of inorganics increased the bulk aerosol hygroscopicity. These days also tended to have higher relative humidity, causing an increase in the water content of the aerosol. Conversely, low-aerosol-loading days had lower sulfate and higher black carbon contributions, causing lower single-scattering albedos (SSAs). The average black carbon concentrations were 240 ng m-3 in the lowest 1 km, decreasing to 35 ng m-3 in the free troposphere (above

  2. [Investigation of chemical composition of propolis extract].

    PubMed

    Majiene, Daiva; Trumbeckaite, Sonata; Grūnoviene, Danguole; Ivanauskas, Liudas; Gendrolis, Antanas

    2004-01-01

    Propolis is a natural product, produced by bees and containing exudates from plants, mixed with bee wax. Propolis and its ethanolic extract are usually used for treatment and prevention of different diseases. Propolis has antibacterial, antiviral, antifungal, anti-inflammatory, anesthetic and immunomodulating properties. Till now there is no data about chemical composition of Lithuanian propolis. Thus, the aim of our work was to investigate the chemical composition of Lithuanian propolis and its ethanolic extract by using gas chromatography / mass spectrometry. We found, that the main structural types of compounds were terpenoids, aromatic and aliphatic acid esters. The most of terpenoids were mono- and sesquiterpens: azulene, alpha-bisabolol, citral, valerenol, etc. Thus, our data show, that the composition of propolis is various and depends on the origin of plants, from where propolis was collected.

  3. Ambient measurements of chemical and physical properties of organic aerosols: Insights into formation, growth, and heterogeneous chemistry

    NASA Astrophysics Data System (ADS)

    Ziemba, Luke D.

    Organic aerosols are a ubiquitous component of the troposphere, from heavily polluted cities to the remote Arctic. In Chapters II, III, and V of this dissertation, the formation of organic aerosol through observations of ambient size distributions is addressed. Chapter IV presents a new pathway for the formation of nitrous acid (HONO) in the urban atmosphere. In Chapter II, the size-resolved chemical composition of sub-micron aerosol was measured at a suburban forested site in North Carolina. Two events were identified in which particle growth, presumably by gas-to-particle conversion, was dominated by accumulation of organic aerosol mass. Growth rates between 1.2 nm hr-1 and 4.9 nm hr-1 were observed. Using a mass-spectral deconvolution method coupled with linear regression analysis, the sub-micron organic aerosol mass observed during the campaign, and during events, was determined to have been influenced by both local and regional secondary processes with only a minor influence from combustion sources. In Chapter III, the chemical characteristics of sub-10-micron aerosol were explored as a function of ambient particle size at a coastal and inland site in New England. Average organic carbon (OC) concentrations of 4.9 microg C m-3 and 3.4 microg C m-3 were observed at the coastal site at the Isles of Shoals (IOS) and at the slightly inland site at Thompson Farm (TF), respectively. An average of 84 and 72% of OC was found to be water-soluble at IOS and TF, respectively. Size distributions indicate that the formation of dicarboxylic acids, especially oxalic acid, is driven by aqueous-phase reactions. A chemical fingerprint analysis suggests that all water-soluble OC at IOS resembles secondary organic aerosol (SOA), while WSOC at TF appears to result from mixed sources. In Chapter IV, a newly identified formation pathway for nitrous acid (HONO) is presented. HONO is an important precursor to hydroxyl radicals in the troposphere and thus contributes to the oxidative

  4. Effects of chemical aging on global secondary organic aerosol using the volatility basis set approach

    NASA Astrophysics Data System (ADS)

    Jo, D. S.; Park, R. J.; Kim, M. J.; Spracklen, D. V.

    2013-12-01

    A global 3-D chemical transport model (GEOS-Chem) is used with the volatility basis set (VBS) approach to examine the effects of chemical aging on global secondary organic aerosol (SOA) concentrations and budgets. We present full-year simulations and their comparisons with the global aerosol mass spectrometer (AMS) dataset, the Interagency Monitoring of Protected Visual Environments (IMPROVE) dataset from the United States, the European Monitoring and Evaluation Programme (EMEP) dataset from Europe, and water-soluble organic carbon observation data collected over East Asia. Using different chemical aging constants, we find that the model results with 4 × 10-11 cm3 molecule-1 s-1 are in better agreement with all observations relative to the model results with other aging constants, without aging, and with the two-product approach. The model simulations are improved when chemical aging is considered, especially for rural regions. However, the simulations still underestimate observed oxygenated organic aerosol (OOA) in urban areas. Two sensitivity simulations including semi-volatile primary organic aerosol (POA) were conducted. We find that including semi-volatile POA improves the model in terms of the hydrogen-like organic aerosol (HOA) to OOA ratio. However, the total OA concentrations are not improved. The total SOA production is considerably increased by 53%, from 26.0 to 39.9 Tg yr-1, after considering chemical aging, remaining lower than top-down estimates of SOA production. Direct radiative forcing (DRF) increases by -0.07 W m-2 due to the chemical aging of SOA, which is comparable to the mean DRF (-0.13 W m-2) of OA from the AeroCom multi-model study. This result indicates considerable global and, more importantly, regional climate implications. For example, the regional DRF change due to chemical aging of SOA in the eastern US is -0.29 W m-2, which is 4 times greater in magnitude than the global mean value.

  5. Lunar Skylights and Their Chemical Compositions

    NASA Astrophysics Data System (ADS)

    Wong, J.; Torres, J.; FitzHoward, S.; Luu, E.; Hua, J.; Irby, R.

    2013-12-01

    In 2009, the Japanese orbiter, SELenological and Engineering Explorer (SELENE) discovered a skylight on the near side of the moon. Skylights are collapsed ceilings of rilles, thought to be caused by moonquakes, meteoroids, or incomplete formation of these lava tube ceilings. Since then, NASA's Lunar Reconnaissance Orbiter has discovered two more skylights, also located on the near side of the moon. Previous research has shown that the physical characteristics of known rilles, can be used as indicators of the presence of yet undiscovered rille and lava dome locations across the lunar surface. We hypothesize that skylights have a signature chemical composition that is unique, and can be used to predict the location of additional skylights on the surface of the moon. For this study, we compared chemical composition data of the three mare sites containing skylights with the 21 mare sites without skylights. Using the software JMARS for the Moon, we compiled multiple datasets to measure the concentrations of 13 different chemical compounds including calcium, iron oxide, titanium dioxide, and thorium. We then conducted a two-tailed T-test of the data, which generated probability values for the mean differences across all 13 chemical compounds of the maria sites with skylights and the maria sites without skylights. Our results show that there is no statistical difference in chemical composition across all of the maria sites examined. Therefore, we conclude that chemical composition does not predict or indicate potential skylight locations on the moon. Further research on other skylight characteristics, for example depth and surrounding underground lava channels, may shed light on the relationships between mare and skylights locations. Three Skylight Locations Found on Lunar Surface 100m View of Mare Tranquilitatis Skylight

  6. Chemical Characterization of Aerosols on the East Coast of the United States Using Aircraft and Ground-Based Stations during the CLAMS Experiment.

    NASA Astrophysics Data System (ADS)

    de Almeida Castanho, Andréa D.; Vanderlei Martins, J.; Hobbs, Peter V.; Artaxo, Paulo; Remer, Lorraine; Yamasoe, Marcia; Colarco, Peter R.

    2005-04-01

    The Chesapeake Lighthouse and Aircraft Measurements for Satellites (CLAMS) experiment was carried out off the central East Coast of the United States in July 2001. During CLAMS, aerosol particle mass was measured at two ground stations and on the University of Washington's Convair 580 research aircraft. Physical and chemical characteristics of the aerosols were identified and quantified. Three main aerosol regimes were identified in the region and are discussed in this work: local pollution/sea salt background, long-range transported dust, and long-range transported pollution. The major component measured in the fine mode of the aerosol on the ground at Wallops Island, Virginia, was sulfate, estimated as NH4HSO4, which accounted for 55% ± 9% on average of the fine particle mass (FPM) during the experiment period. Black carbon concentrations accounted for 3% ± 1% of FPM; soil dust was also present, representing on average 6% ± 8% of FPM. The difference between the sum of the masses of the measured compounds and the total fine particle mass was 36% ± 10% of FPM, which is attributed primarily to nitrates and organic carbon that were not measured. Aerosol chemical composition in the atmospheric column is also discussed and compared with ground-based measurements. Aerosol dust concentration reached 40% of FPM during an incursion of Saharan dust between 24 and 26 July. Sulfate aerosol reached 70% of FPM during the transport of regional pollution on 17 July. Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical thickness, coupled with air parcel back trajectories, supported the conclusion of episodes of long-range transport of dust from the Sahara Desert and pollutants from the continental United States.

  7. Experience of direct impactor measurements of the structure and composition of stratospheric aerosols in polar latitudes

    NASA Astrophysics Data System (ADS)

    Kondratyev, K. Y.; Ivlev, Leo S.; Ivanov, V. A.; Zhukov, V. M.

    1993-11-01

    The data obtained in 1989 during the launchings to the stratosphere of a two-cascade impactor from the test ground in Apatity have been discussed. The aerosol samples have been analyzed using an electronic microscope to have information on the structure and size distribution of aerosol particles. The chemical and elemental analyses have been made using the methods of mass-spectrometry, IR spectroscopy, neutron activation, and x-ray fluorescence.

  8. Aircraft measurements over Europe of an air pollution plume from Southeast Asia - aerosol and chemical characterization

    NASA Astrophysics Data System (ADS)

    Stohl, A.; Forster, C.; Huntrieser, H.; Mannstein, H.; McMillan, W. W.; Petzold, A.; Schlager, H.; Weinzierl, B.

    2007-02-01

    An air pollution plume from Southern and Eastern Asia, including regions in India and China, was predicted by the FLEXPART particle dispersion model to arrive in the upper troposphere over Europe on 24-25 March 2006. According to the model, the plume was exported from Southeast Asia six days earlier, transported into the upper troposphere by a warm conveyor belt, and travelled to Europe in a fast zonal flow. This is confirmed by the retrievals of carbon monoxide (CO) from AIRS satellite measurements, which are in excellent agreement with the model results over the entire transport history. The research aircraft DLR Falcon was sent into this plume west of Spain on 24 March and over Southern Europe on 25 March. On both days, the pollution plume was found close to the predicted locations and, thus, the measurements taken allowed the first detailed characterization of the aerosol content and chemical composition of an anthropogenic pollution plume after a nearly hemispheric transport event. The mixing ratios of CO, reactive nitrogen (NOy) and ozone (O3) measured in the Asian plume were all clearly elevated over a background that was itself likely elevated by Asian emissions: CO by 17-34 ppbv on average (maximum 60 ppbv) and O3 by 2-9 ppbv (maximum 22 ppbv). Positive correlations existed between these species, and a ΔO3/ΔCO slope of 0.25 shows that ozone was formed in this plume, albeit with moderate efficiency. Nucleation mode and Aitken particles were suppressed in the Asian plume, whereas accumulation mode aerosols were strongly elevated and correlated with CO. The suppression of the nucleation mode was likely due to the large pre-existing aerosol surface of the transported larger particles. Super-micron particles, likely desert dust, were found in part of the Asian pollution plume and also in surrounding cleaner air. The aerosol light absorption coefficient was enhanced in the plume (average values for individual plume encounters 0.25-0.70 Mm-1), as was the

  9. Aircraft measurements over Europe of an air pollution plume from Southeast Asia - aerosol and chemical characterization

    NASA Astrophysics Data System (ADS)

    Stohl, A.; Forster, C.; Huntrieser, H.; Mannstein, H.; McMillan, W. W.; Petzold, A.; Schlager, H.; Weinzierl, B.

    2006-12-01

    An air pollution plume from Southern and Eastern Asia, including regions in India and China, was predicted by the FLEXPART particle dispersion model to arrive in the upper troposphere over Europe on 24-25 March 2006. According to the model, the plume was exported from Southeast Asia only six days earlier, transported into the upper troposphere by a warm conveyor belt, and travelled to Europe in a fast zonal flow. This is confirmed by the retrievals of carbon monoxide (CO) from AIRS satellite measurements, which are in excellent agreement with the model results over the entire transport history. The research aircraft DLR Falcon was sent into this plume west of Spain on 24 March and over Southern Europe on 25 March. On both days, the pollution plume was indeed found close to the predicted locations and, thus, the measurements taken allowed the first detailed characterization of the aerosol content and chemical composition of an anthropogenic pollution plume after a nearly hemispheric transport event. The mixing ratios of CO, reactive nitrogen (NOy) and ozone (O3) measured in the Asian plume were all clearly elevated over a background that was itself likely elevated by Asian emissions: CO by 17-34 ppbv on average (maximum 60 ppbv) and O3 by 2-9 ppbv (maximum 22 ppbv). Positive correlations existed between these species, and a ΔO3/ΔCO slope of 0.25 shows that ozone was formed in this plume, albeit with moderate efficiency. Nucleation mode and Aitken particles were suppressed in the Asian plume, whereas accumulation mode aerosols were strongly elevated and correlated with CO. The suppression of the nucleation mode was likely due to the large pre-existing aerosol surface due to the transported larger particles. Super-micron particles, likely desert dust, were found in part of the Asian pollution plume and also in surrounding cleaner air. The aerosol light absorption coefficient was enhanced in the plume (average values for individual plume encounters 0.25-0.70 Mm-1

  10. Long-term trends in aerosol and precipitation composition over the western North Atlantic Ocean at Bermuda

    NASA Astrophysics Data System (ADS)

    Keene, W. C.; Moody, J. L.; Galloway, J. N.; Prospero, J. M.; Cooper, O. R.; Eckhardt, S.; Maben, J. R.

    2014-08-01

    Since the 1980s, emissions of SO2 and NOx (NO + NO2) from anthropogenic sources in the United States (US), Canada, and Europe have decreased significantly suggesting that the export of oxidized S and N compounds from surrounding continents to the atmosphere overlying the North Atlantic Ocean (NAO) has also decreased. The chemical compositions of aerosols and precipitation sampled daily on Bermuda (32.27° N, 64.87° W) from 1989 to 1997 and from 2006 to 2009 were evaluated to quantify the magnitudes, significance, and implications of associated tends in atmospheric composition. The chemical data were stratified based on FLEXPART (FLEXible PARTicle dispersion model) retroplumes into four discrete transport regimes: westerly flow from eastern North America (NEUS/SEUS); easterly trade-wind flow from northern Africa and the subtropical NAO (Africa); long, open-ocean, anticyclonic flow around the Bermuda High (Oceanic); and transitional flow from the relatively clean open ocean to the polluted eastern North America (North). Based on all data, annual average concentrations of non-sea-salt (nss) SO42- associated with aerosols and annual volume-weighted-average (VWA) concentrations in precipitation decreased significantly (by 22% and 49%, respectively) whereas annual VWA concentrations of NH4+ in precipitation increased significantly (by 70%). Corresponding trends in aerosol and precipitation NO3- and of aerosol NH4+ were insignificant. Nss SO42- in precipitation under NEUS/SEUS and Oceanic flow decreased significantly (61% each) whereas corresponding trends in particulate nss SO42- under both flow regimes were insignificant. Trends in precipitation composition were driven in part by decreasing emissions of SO2 over upwind continents and associated decreases in anthropogenic contributions to nss SO42- concentrations. Under NEUS/SEUS and Oceanic flow, the ratio of anthropogenic to biogenic contributions to nss SO42- in the column scavenged by precipitation were relatively

  11. Aerosol physical, chemical and optical properties observed in the ambient atmosphere during haze pollution conditions

    NASA Astrophysics Data System (ADS)

    Li, Zhengqiang; Xie, Yisong; Li, Donghui; Li, Kaitao; Zhang, Ying; Li, Li; Lv, Yang; Qie, Lili; Xu, Hua

    Aerosol’s properties in the ambient atmosphere may differ significantly from sampling results due to containing of abundant water content. We performed sun-sky radiometer measurements in Beijing during 2011 and 2012 winter to obtain distribution of spectral and angular sky radiance. The measurements are then used to retrieve aerosol physical, chemical and optical properties, including single scattering albedo, size distribution, complex refractive indices and aerosol component fractions identified as black carbon, brown carbon, mineral dust, ammonium sulfate-like components and water content inside particle matters. We found that during winter haze condition aerosol is dominated by fine particles with center radius of about 0.2 micron. Fine particles contribute about 93% to total aerosol extinction of solar light, and result in serious decrease of atmospheric visibility during haze condition. The percentage of light absorption of haze aerosol can up to about 10% among its total extinction, much higher than that of unpolluted conditions, that causes significant radiative cooling effects suppressing atmospheric convection and dispersion of pollutants. Moreover, the average water content occupies about one third of the ambient aerosol in volume which suggests the important effect of ambient humidity in the formation of haze pollution.

  12. Determination of chemical composition of Turkish propolis.

    PubMed

    Sorkun, K; Süer, B; Salih, B

    2001-01-01

    The aim of the present work is to study the chemical composition of Turkish propolis. Propolis samples were collected from different regions of Turkey (Bursa, Erzurum-Askale, Gumushane-Sogutagil and Trabzon-Caglayan) in 1999. Ethanol extracts of propolis (EEP) were prepared for chemical analysis, using gas chromatograph coupled with mass spectrometry (GC-MS). Our findings show that propolis samples from Trabzon and Gumushane region have a similar chemical composition. In both samples aromatic acids, aliphatic acids and their esters, and also ketone derivatives are the main compound groups. The chemical composition of the single sample that was collected from Erzurum region shows a very different pattern than the other two samples. In this propolis, the main compounds are aromatic acid esters and alcohols. However, it contains a high amount of amino acids compared to the other samples. The other samples collected from three different region of Bursa City are rich with flavavones, aromatic acids and their esters, terpenoids, flavones and ketones.

  13. Aerosol chemical vapor deposition of metal oxide films

    DOEpatents

    Ott, K.C.; Kodas, T.T.

    1994-01-11

    A process of preparing a film of a multicomponent metal oxide including: forming an aerosol from a solution comprised of a suitable solvent and at least two precursor compounds capable of volatilizing at temperatures lower than the decomposition temperature of said precursor compounds; passing said aerosol in combination with a suitable oxygen-containing carrier gas into a heated zone, said heated zone having a temperature sufficient to evaporate the solvent and volatilize said precursor compounds; and passing said volatilized precursor compounds against the surface of a substrate, said substrate having a sufficient temperature to decompose said volatilized precursor compounds whereby metal atoms contained within said volatilized precursor compounds are deposited as a metal oxide film upon the substrate is disclosed. In addition, a coated article comprising a multicomponent metal oxide film conforming to the surface of a substrate selected from the group consisting of silicon, magnesium oxide, yttrium-stabilized zirconium oxide, sapphire, or lanthanum gallate, said multicomponent metal oxide film characterized as having a substantially uniform thickness upon said substrate.

  14. Modelling of primary aerosols in the chemical transport model MOCAGE: development and evaluation of aerosol physical parameterizations

    NASA Astrophysics Data System (ADS)

    Sič, B.; El Amraoui, L.; Marécal, V.; Josse, B.; Arteta, J.; Guth, J.; Joly, M.; Hamer, P. D.

    2015-02-01

    This paper deals with recent improvements to the global chemical transport model of Météo-France MOCAGE (Modèle de Chimie Atmosphérique à Grande Echelle) that consists of updates to different aerosol parameterizations. MOCAGE only contains primary aerosol species: desert dust, sea salt, black carbon, organic carbon, and also volcanic ash in the case of large volcanic eruptions. We introduced important changes to the aerosol parameterization concerning emissions, wet deposition and sedimentation. For the emissions, size distribution and wind calculations are modified for desert dust aerosols, and a surface sea temperature dependant source function is introduced for sea salt aerosols. Wet deposition is modified toward a more physically realistic representation by introducing re-evaporation of falling rain and snowfall scavenging and by changing the in-cloud scavenging scheme along with calculations of precipitation cloud cover and rain properties. The sedimentation scheme update includes changes regarding the stability and viscosity calculations. Independent data from satellites (MODIS, SEVIRI), the ground (AERONET, EMEP), and a model inter-comparison project (AeroCom) are compared with MOCAGE simulations and show that the introduced changes brought a significant improvement on aerosol representation, properties and global distribution. Emitted quantities of desert dust and sea salt, as well their lifetimes, moved closer towards values of AeroCom estimates and the multi-model average. When comparing the model simulations with MODIS aerosol optical depth (AOD) observations over the oceans, the updated model configuration shows a decrease in the modified normalized mean bias (MNMB; from 0.42 to 0.10) and a better correlation (from 0.06 to 0.32) in terms of the geographical distribution and the temporal variability. The updates corrected a strong positive MNMB in the sea salt representation at high latitudes (from 0.65 to 0.16), and a negative MNMB in the desert

  15. Hygroscopic and chemical properties of aerosols collected near a copper smelter: implications for public and environmental health.

    PubMed

    Sorooshian, Armin; Csavina, Janae; Shingler, Taylor; Dey, Stephen; Brechtel, Fred J; Sáez, A Eduardo; Betterton, Eric A

    2012-09-04

    Particulate matter emissions near active copper smelters and mine tailings in the southwestern United States pose a potential threat to nearby environments owing to toxic species that can be inhaled and deposited in various regions of the body depending on the composition and size of the particles, which are linked by particle hygroscopic properties. This study reports the first simultaneous measurements of size-resolved chemical and hygroscopic properties of particles next to an active copper smelter and mine tailings by the towns of Hayden and Winkelman in southern Arizona. Size-resolved particulate matter samples were examined with inductively coupled plasma mass spectrometry, ion chromatography, and a humidified tandem differential mobility analyzer. Aerosol particles collected at the measurement site are enriched in metals and metalloids (e.g., arsenic, lead, and cadmium) and water-uptake measurements of aqueous extracts of collected samples indicate that the particle diameter range of particles most enriched with these species (0.18-0.55 μm) overlaps with the most hygroscopic mode at a relative humidity of 90% (0.10-0.32 μm). These measurements have implications for public health, microphysical effects of aerosols, and regional impacts owing to the transport and deposition of contaminated aerosol particles.

  16. Hygroscopic and Chemical Properties of Aerosols collected near a Copper Smelter: Implications for Public and Environmental Health

    PubMed Central

    Sorooshian, Armin; Csavina, Janae; Shingler, Taylor; Dey, Stephen; Brechtel, Fred J.; Sáez, A. Eduardo; Betterton, Eric A.

    2012-01-01

    Particulate matter emissions near active copper smelters and mine tailings in the southwestern United States pose a potential threat to nearby environments owing to toxic species that can be inhaled and deposited in various regions of the body depending on the composition and size of the particles, which are linked by particle hygroscopic properties. This study reports the first simultaneous measurements of size-resolved chemical and hygroscopic properties of particles next to an active copper smelter and mine tailings by the towns of Hayden and Winkelman in southern Arizona. Size-resolved particulate matter samples collected near an active copper smelter were examined with inductively coupled plasma mass spectrometry, ion chromatography, and a humidified tandem differential mobility analyzer. Aerosol particles collected at the measurement site are enriched in metals and metalloids (e.g. arsenic, lead, and cadmium) and water-uptake measurements of aqueous extracts of collected samples indicate that the particle diameter range of particles most enriched with these species (0.18–0.55 µm) overlaps with the most hygroscopic mode at a relative humidity of 90% (0.10–0.32 µm). These measurements have implications for public health, microphysical effects of aerosols, and regional impacts owing to the transport and deposition of contaminated aerosol particles. PMID:22852879

  17. Optical and chemical characterization of aerosols emitted from coal, heavy and light fuel oil, and small-scale wood combustion.

    PubMed

    Frey, Anna K; Saarnio, Karri; Lamberg, Heikki; Mylläri, Fanni; Karjalainen, Panu; Teinilä, Kimmo; Carbone, Samara; Tissari, Jarkko; Niemelä, Ville; Häyrinen, Anna; Rautiainen, Jani; Kytömäki, Jorma; Artaxo, Paulo; Virkkula, Aki; Pirjola, Liisa; Rönkkö, Topi; Keskinen, Jorma; Jokiniemi, Jorma; Hillamo, Risto

    2014-01-01

    Particle emissions affect radiative forcing in the atmosphere. Therefore, it is essential to know the physical and chemical characteristics of them. This work studied the chemical, physical, and optical characteristics of particle emissions from small-scale wood combustion, coal combustion of a heating and power plant, as well as heavy and light fuel oil combustion at a district heating station. Fine particle (PM1) emissions were the highest in wood combustion with a high fraction of absorbing material. The emissions were lowest from coal combustion mostly because of efficient cleaning techniques used at the power plant. The chemical composition of aerosols from coal and oil combustion included mostly ions and trace elements with a rather low fraction of absorbing material. The single scattering albedo and aerosol forcing efficiency showed that primary particles emitted from wood combustion and some cases of oil combustion would have a clear climate warming effect even over dark earth surfaces. Instead, coal combustion particle emissions had a cooling effect. Secondary processes in the atmosphere will further change the radiative properties of these emissions but are not considered in this study.

  18. Long-range-transported Saharan dust in the Caribbean - an electron microscopy perspective of aerosol composition and modification

    NASA Astrophysics Data System (ADS)

    Kandler, Konrad; Hartmann, Markus; Ebert, Martin; Weinbruch, Stephan; Weinzierl, Bernadett; Walser, Adrian; Sauer, Daniel; Wadinga Fomba, Khanneh

    2015-04-01

    From June to July in 2013, the Saharan Aerosol Long-range Transport and Aerosol-Cloud-Interaction Experiment (SALTRACE) was performed in the Caribbean. Airborne aerosol sampling was performed onboard the DLR Falcon aircraft in altitudes between 300 m and 5500 m. Ground-based samples were collected at Ragged Point (Barbados, 13.165 °N, 59.432 °W) and at the Cape Verde Atmospheric Observatory (Sao Vicente, 16.864 °N, 24.868 °W). Different types of impactors and sedimentation samplers were used to collect particles between 0.1 µm and 4 µm (airborne) and between 0.1 µm and 100 µm (ground-based). Particles were analyzed by scanning electron microscopy with attached energy-dispersive X-ray analysis, yielding information on particle size, particle shape and chemical composition for elements heavier than nitrogen. A particle size correction was applied to the chemical data to yield better quantification. A total of approximately 100,000 particles were analyzed. For particles larger than 0.7 µm, the aerosol in the Caribbean during the campaign was a mixture of mineral dust, sea-salt at different aging states, and sulfate. Inside the Saharan dust plume - outside the marine boundary layer (MBL) - the aerosol is absolutely dominated by mineral dust. Inside the upper MBL, sea-salt exists as minor component in the aerosol for particles smaller than 2 µm in diameter, larger ones are practically dust only. When crossing the Soufriere Hills volcano plume with the aircraft, an extremely high abundance of small sulfate particles could be observed. At Ragged Point, in contrast to the airborne measurements, aerosol is frequently dominated by sea-salt particles. Dust relative abundance at Ragged Point has a maximum between 5 µm and 10 µm particles diameter; at larger sizes, sea-salt again prevails due to the sea-spray influence. A significant number of dust particles larger than 20 µm was encountered. The dust component in the Caribbean - airborne as well as ground

  19. Collocated observations of cloud condensation nuclei, particle size distributions, and chemical composition.

    PubMed

    Schmale, Julia; Henning, Silvia; Henzing, Bas; Keskinen, Helmi; Sellegri, Karine; Ovadnevaite, Jurgita; Bougiatioti, Aikaterini; Kalivitis, Nikos; Stavroulas, Iasonas; Jefferson, Anne; Park, Minsu; Schlag, Patrick; Kristensson, Adam; Iwamoto, Yoko; Pringle, Kirsty; Reddington, Carly; Aalto, Pasi; Äijälä, Mikko; Baltensperger, Urs; Bialek, Jakub; Birmili, Wolfram; Bukowiecki, Nicolas; Ehn, Mikael; Fjæraa, Ann Mari; Fiebig, Markus; Frank, Göran; Fröhlich, Roman; Frumau, Arnoud; Furuya, Masaki; Hammer, Emanuel; Heikkinen, Liine; Herrmann, Erik; Holzinger, Rupert; Hyono, Hiroyuki; Kanakidou, Maria; Kiendler-Scharr, Astrid; Kinouchi, Kento; Kos, Gerard; Kulmala, Markku; Mihalopoulos, Nikolaos; Motos, Ghislain; Nenes, Athanasios; O'Dowd, Colin; Paramonov, Mikhail; Petäjä, Tuukka; Picard, David; Poulain, Laurent; Prévôt, André Stephan Henry; Slowik, Jay; Sonntag, Andre; Swietlicki, Erik; Svenningsson, Birgitta; Tsurumaru, Hiroshi; Wiedensohler, Alfred; Wittbom, Cerina; Ogren, John A; Matsuki, Atsushi; Yum, Seong Soo; Myhre, Cathrine Lund; Carslaw, Ken; Stratmann, Frank; Gysel, Martin

    2017-03-14

    Cloud condensation nuclei (CCN) number concentrations alongside with submicrometer particle number size distributions and particle chemical composition have been measured at atmospheric observatories of the Aerosols, Clouds, and Trace gases Research InfraStructure (ACTRIS) as well as other international sites over multiple years. Here, harmonized data records from 11 observatories are summarized, spanning 98,677 instrument hours for CCN data, 157,880 for particle number size distributions, and 70,817 for chemical composition data. The observatories represent nine different environments, e.g., Arctic, Atlantic, Pacific and Mediterranean maritime, boreal forest, or high alpine atmospheric conditions. This is a unique collection of aerosol particle properties most relevant for studying aerosol-cloud interactions which constitute the largest uncertainty in anthropogenic radiative forcing of the climate. The dataset is appropriate for comprehensive aerosol characterization (e.g., closure studies of CCN), model-measurement intercomparison and satellite retrieval method evaluation, among others. Data have been acquired and processed following international recommendations for quality assurance and have undergone multiple stages of quality assessment.

  20. Collocated observations of cloud condensation nuclei, particle size distributions, and chemical composition

    PubMed Central

    Schmale, Julia; Henning, Silvia; Henzing, Bas; Keskinen, Helmi; Sellegri, Karine; Ovadnevaite, Jurgita; Bougiatioti, Aikaterini; Kalivitis, Nikos; Stavroulas, Iasonas; Jefferson, Anne; Park, Minsu; Schlag, Patrick; Kristensson, Adam; Iwamoto, Yoko; Pringle, Kirsty; Reddington, Carly; Aalto, Pasi; Äijälä, Mikko; Baltensperger, Urs; Bialek, Jakub; Birmili, Wolfram; Bukowiecki, Nicolas; Ehn, Mikael; Fjæraa, Ann Mari; Fiebig, Markus; Frank, Göran; Fröhlich, Roman; Frumau, Arnoud; Furuya, Masaki; Hammer, Emanuel; Heikkinen, Liine; Herrmann, Erik; Holzinger, Rupert; Hyono, Hiroyuki; Kanakidou, Maria; Kiendler-Scharr, Astrid; Kinouchi, Kento; Kos, Gerard; Kulmala, Markku; Mihalopoulos, Nikolaos; Motos, Ghislain; Nenes, Athanasios; O’Dowd, Colin; Paramonov, Mikhail; Petäjä, Tuukka; Picard, David; Poulain, Laurent; Prévôt, André Stephan Henry; Slowik, Jay; Sonntag, Andre; Swietlicki, Erik; Svenningsson, Birgitta; Tsurumaru, Hiroshi; Wiedensohler, Alfred; Wittbom, Cerina; Ogren, John A.; Matsuki, Atsushi; Yum, Seong Soo; Myhre, Cathrine Lund; Carslaw, Ken; Stratmann, Frank; Gysel, Martin

    2017-01-01

    Cloud condensation nuclei (CCN) number concentrations alongside with submicrometer particle number size distributions and particle chemical composition have been measured at atmospheric observatories of the Aerosols, Clouds, and Trace gases Research InfraStructure (ACTRIS) as well as other international sites over multiple years. Here, harmonized data records from 11 observatories are summarized, spanning 98,677 instrument hours for CCN data, 157,880 for particle number size distributions, and 70,817 for chemical composition data. The observatories represent nine different environments, e.g., Arctic, Atlantic, Pacific and Mediterranean maritime, boreal forest, or high alpine atmospheric conditions. This is a unique collection of aerosol particle properties most relevant for studying aerosol-cloud interactions which constitute the largest uncertainty in anthropogenic radiative forcing of the climate. The dataset is appropriate for comprehensive aerosol characterization (e.g., closure studies of CCN), model-measurement intercomparison and satellite retrieval method evaluation, among others. Data have been acquired and processed following international recommendations for quality assurance and have undergone multiple stages of quality assessment. PMID:28291234