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Sample records for ambient aerosols collected

  1. Speciation of arsenic in ambient aerosols collected in Los Angeles.

    PubMed

    Rabano, E S; Castillo, N T; Torre, K J; Solomon, P A

    1989-01-01

    First-time measurements of the potentially toxic inorganic species of arsenic (arsenite and arsenate) have been obtained in fine (less than 2.5 microns AD) and coarse (greater than 2.5 microns AD) atmospheric particles in the Los Angeles area. A recently developed method that includes procedures for sample collection, preparation, and analysis was used in this study. Size-fractionated aerosol samples were collected with a high-volume dichotomous virtual impactor that employed polytetrafluoroethylene filters. Results were obtained for the recovery of arsenic standards added to unexposed and collected filters. Data from this study, indicated that the recently developed speciation method can be used to determine concentrations of As(III) and As(V) in atmospheric particulate matter samples. Size-fractionated aerosol samples were collected in the city of Industry during January and February 1987. In most samples, As(III) and As(V) were above the detection limit (approximately 1 ng m-3 of either species) in both aerosol size fractions. A greater portion (about 75 percent) of the two species were observed in the fine particles. The As(III)/As(V) ratio for both particle sizes was close to 1 (i.e., an equal mixture of both species). Comparison of total suspended particulate arsenic measured by the speciation method to that measured by a routine California Air Resources Board-approved procedure showed good agreement (r = 0.94), indicating both methods were approximately equivalent for the collection and analysis of aerosol arsenic. PMID:2709077

  2. CCN activation of ambient and "synthetic ambient" urban aerosol

    NASA Astrophysics Data System (ADS)

    Burkart, Julia; Reischl, Georg; Steiner, Gerhard; Bauer, Heidi; Leder, Klaus; Kistler, Magda; Puxbaum, Hans; Hitzenberger, R.

    2013-05-01

    In this study, the Cloud Condensation Nuclei (CCN) activation properties of the urban aerosol in Vienna, Austria, were investigated in a long term (11 month) field study. Filter samples of the aerosol below 100 nm were taken in parallel to these measurements, and later used to generate "synthetic ambient" aerosols. Activation parameters of this "synthetic ambient" aerosol were also obtained. Hygroscopicity parameters κ [1] were calculated both for the urban and the "synthetic ambient" aerosol and also from the chemical composition. Average κ for the "synthetic ambient" aerosol ranged from 0.20 to 0.30 with an average value of 0.24, while the κ from the chemical composition of this "synthetic ambient" aerosol was significantly higher (average 0.43). The full results of the study are given elsewhere [2,3].

  3. Characterization of selenium in ambient aerosols and primary emission sources.

    PubMed

    De Santiago, Arlette; Longo, Amelia F; Ingall, Ellery D; Diaz, Julia M; King, Laura E; Lai, Barry; Weber, Rodney J; Russell, Armistead G; Oakes, Michelle

    2014-08-19

    Atmospheric selenium (Se) in aerosols was investigated using X-ray absorption near-edge structure (XANES) spectroscopy and X-ray fluorescence (XRF) microscopy. These techniques were used to determine the oxidation state and elemental associations of Se in common primary emission sources and ambient aerosols collected from the greater Atlanta area. In the majority of ambient aerosol and primary emission source samples, the spectroscopic patterns as well as the absence of elemental correlations suggest Se is in an elemental, organic, or oxide form. XRF microscopy revealed numerous Se-rich particles, or hotspots, accounting on average for ∼16% of the total Se in ambient aerosols. Hotspots contained primarily Se(0)/Se(-II). However, larger, bulk spectroscopic characterizations revealed Se(IV) as the dominant oxidation state in ambient aerosol, followed by Se(0)/Se(-II) and Se(VI). Se(IV) was the only observed oxidation state in gasoline, diesel, and coal fly ash, while biomass burning contained a combination of Se(0)/Se(-II) and Se(IV). Although the majority of Se in aerosols was in the most toxic form, the Se concentration is well below the California Environmental Protection Agency chronic exposure limit (∼20000 ng/m(3)). PMID:25075640

  4. Analytical techniques for ambient sulfate aerosols

    SciTech Connect

    Johnson, S.A.; Graczyk, D.G.; Kumar, R.; Cunningham, P.T.

    1981-06-01

    Work done to further develop the infrared spectroscopic analytical method for the analysis of atmospheric aerosol particles, as well as some exploratory work on a new procedure for determining proton acidity in aerosol samples is described. Earlier work had led to the successful use of infrared (ir) spectrophotometry for the analysis of nitrate, ammonium, and neutral and acidic sulfates in aerosol samples collected by an impactor on a Mylar-film substrate. In this work, a filter-extraction method was developed to prepare filter-collected aerosol samples for ir analysis. A study was made comparing the ir analytical results on filter-collected samples with impactor-collected samples. Also, the infrared analytical technique was compared in field studies with light-scattering techniques for aerosol analysis. A highly sensitive instrument for aerosol analysis using attenuated total internal reflection (ATR) infrared spectroscopy was designed, built, and tested. This instrument provides a measurement sensitivity much greater (by a factor of 6 for SO/sub 4//sup 2 -/) than that obtainable using the KBr-pellet method. This instrument collect size- and time-resolved samples and is potentially capable of providing automated, near real-time aerosol analysis. Exploratory work on a novel approach to the determination of proton acidity in filter- or impactor-collected aerosol samples is also described. In this technique, the acidic sample is reacted with an access of a tagged, vapor-phase base. The unreacted base is flushed off and the amount of the tag retained by the sample is a direct measure of the proton acidity of the sample. The base was tagged with Ge, which can be conveniently determined by the x-ray fluorescence technique.

  5. Analysis of Anions in Ambient Aerosols by Microchip Capillary Electrophoresis

    SciTech Connect

    Liu, Yan; MacDonald, David A.; Yu, Xiao-Ying; Hering, Susanne V.; Collett, Jeffrey L.; Henry, Charles S.

    2006-10-01

    We describe a microchip capillary electrophoresis method for the analysis of nitrate and sulfate in ambient aerosols. Investigating the chemical composition of ambient aerosol particles is essential for understanding their sources and effects. Significant progress has been made towards developing mass spectrometry-based instrumentation for rapid qualitative analysis of aerosols. Alternative methods for rapid quantification of selected high abundance compounds are needed to augment the capacity for widespread routine analysis. Such methods could provide much higher temporal and spatial resolution than can be achieved currently. Inorganic anions comprise a large percentage of particulate mass with nitrate and sulfate among the most abundant species. While ion chromatography has proven very useful for analyzing extracts of time-integrated ambient aerosol samples collected on filters and for semi-continuous, on-line particle composition measurements, there is a growing need for development of new compact, inexpensive approaches to routine on-line aerosol ion analysis for deployment in spatially dense, atmospheric measurement networks. Microchip capillary electrophoresis provides the necessary speed and portability to address this need. In this report, on-column contact conductivity detection is used with hydrodynamic injection to create a simple microchip instrument for analysis of nitrate and sulfate. On-column contact conductivity detection was achieved using a Pd decoupler placed upstream from the working electrodes. Microchips containing two Au or Pd working electrodes showed a good linear range (5-500 µM) and low limits-of-detection for sulfate and nitrate with Au providing the lowest detection limits (1 µM) for both ions. The completed microchip system was used to analyze ambient aerosol filter samples. Nitrate and sulfate concentrations measured by the microchip matched the concentrations measured by ion chromatography.

  6. 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.

  7. eDPS Aerosol Collection

    SciTech Connect

    Venzie, J.

    2015-10-13

    The eDPS Aerosol Collection project studies the fundamental physics of electrostatic aerosol collection for national security applications. The interpretation of aerosol data requires understanding and correcting for biases introduced from particle genesis through collection and analysis. The research and development undertaken in this project provides the basis for both the statistical correction of existing equipment and techniques; as well as, the development of new collectors and analytical techniques designed to minimize unwanted biases while improving the efficiency of locating and measuring individual particles of interest.

  8. Stable carbon and nitrogen isotopic compositions of ambient aerosols collected from Okinawa Island in the western North Pacific Rim, an outflow region of Asian dusts and pollutants

    NASA Astrophysics Data System (ADS)

    Kunwar, Bhagawati; Kawamura, Kimitaka; Zhu, Chunmao

    2016-04-01

    Stable carbon (δ13C) and nitrogen (δ15N) isotope ratios were measured for total carbon (TC) and nitrogen (TN), respectively, in aerosol (TSP) samples collected at Cape Hedo, Okinawa, an outflow region of Asian pollutants, during 2009-2010. The averaged δ13C and δ15N ratios are -22.2‰ and +12.5‰, respectively. The δ13C values are similar in both spring (-22.5‰) and winter (-22.5‰), suggesting the similar sources and/or source regions. We found that δ13C from Okinawa aerosols are ca. 2‰ higher than those reported from Chinese megacities probably due to photochemical aging of organic aerosols. A strong correlation (r = 0.81) was found between nss-Ca and TSP, suggesting that springtime aerosols are influenced from Asian dusts. However, carbonates in the Asian dusts were titrated with acidic species such as sulfuric acid and oxalic acid during atmospheric transport although two samples suggested the presence of remaining carbonate. No correlations were found between δ13C and tracer compounds (levoglucosan, elemental carbon, oxalic acid, and Na+). During winter and spring, coal burning is significant source in China. Based on isotopic mass balance, contribution of coal burning origin particles to total aerosol carbon was estimated as ca. 97% in winter, which is probably associated with the high emissions in China. Contribution of NO3- to TN was on average 45% whereas that of NH4+ was 18%. These results suggest that vehicular exhaust is an important source of TN in Okinawa aerosols. Concentration of water-soluble organic nitrogen (WSON) is higher in summer, suggesting that WSON is more emitted from the ocean in warmer season whereas inorganic nitrogen is more emitted in winter and spring from pollution sources in the Asian continent.

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

    PubMed

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

    2016-09-20

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

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

    PubMed

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

    2016-09-20

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

  11. RADIOCARBON ANALYSIS OF PM 2.5 AMBIENT AEROSOL

    EPA Science Inventory

    The radiocarbon (14C) content of an ambient aerosol sample can be directly related to the fraction of the sample's total carbon mass contributed by natural (biogenic) sources. Such knowledge is difficult to determine by other means, and important for devising ambient PM contro...

  12. Deliquescent phenomena of ambient aerosols on the North China Plain

    NASA Astrophysics Data System (ADS)

    Kuang, Y.; Zhao, C. S.; Ma, N.; Liu, H. J.; Bian, Y. X.; Tao, J. C.; Hu, Min

    2016-08-01

    In this study, we report that the deliquescent phenomena of ambient aerosols on the North China Plain are frequently observed using a humidified nephelometer system. The deliquescence relative humidity (RH) primarily ranges from 73% to 81%, with an average of 76.8%. The observed deliquescent phenomena of ambient aerosols exhibit distinct diurnal patterns and are highly correlated with ammonium sulfate. The diurnal variations of ammonium and nitrate may play significant roles on occurrences of observed deliquescent phenomena. The frequently observed deliquescent phenomena of ambient aerosols in this paper imply that current parameterization schemes that describe the RH dependence of particle light scattering may result in a significant bias when estimating aerosol effects on climate.

  13. Characteristics of 2-methyltetrols in ambient aerosol in Beijing, China

    NASA Astrophysics Data System (ADS)

    Liang, Linlin; Engling, Guenter; Duan, Fengkui; Cheng, Yuan; He, Kebin

    2012-11-01

    PM10 and PM2.5 samples were collected from November, 2010 to October, 2011 at Tsinghua University in Beijing. Various carbohydrates were quantified by high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD), including the 2-methyltetrols (2-methylthreitol and 2-methylerythritol). A clear seasonal variation in the ambient 2-methyltetrol concentrations was observed, with the highest levels occurring in the summer, followed by autumn, spring and winter. The average concentrations of the 2-methyltetrols in PM10 and PM2.5 were 17.5 ± 15.4 ng m-3 and 13.8 ± 12.2 ng m-3, respectively. The 2-methyltetrols exhibited significant positive correlations with ambient relative humidity and temperature, likely due to the higher isoprene emission strength and enhanced formation yield under higher temperature and humidity conditions. In contrast, there was no relationship between the concentration of 2-methyltetrols and sunshine duration. The significant positive correlation (R2 = 0.76) between 2-methyltetrols and SO42- indicated that high concentrations of SO42- can increase the formation rate of 2-methyltetrols from isoprene. Moreover, 2-methyltetrols were also observed in the winter time in Beijing, illustrating the enhancement of the 2-methyltetrol formation rate by high concentrations of pollutants in ambient aerosol.

  14. Ambient Observations of Aerosols, Novel Aerosol Structures, And Their Engineering Applications

    NASA Astrophysics Data System (ADS)

    Beres, Nicholas D.

    The role of atmospheric aerosols remains a crucial issue in understanding and mitigating climate change in our world today. These particles influence the Earth by altering the Earth's delicate radiation balance, human health, and visibility. In particular, black carbon particulate matter remains the key driver in positive radiative forcing (i.e., warming) due to aerosols. Produced from the incomplete combustion of hydrocarbons, these compounds can be found in many different forms around the globe. This thesis provides an overview of three research topics: (1) the ambient characterization of aerosols in the Northern Indian Ocean, measurement techniques used, and how these aerosols influence local, regional, and global climate; (2) the exploration of novel soot superaggregate particles collected in the Northern Indian Ocean and around the globe and how the properties of these particles relate to human health and climate forcing; and (3) how aerogelated soot can be produced in a novel, one-step method utilizing an inverted flame reactor and how this material could be used in industrial settings.

  15. Direct Observations of the Composition of Sub-20 Nanometer Ambient Aerosol

    NASA Astrophysics Data System (ADS)

    Moore, K. F.; Smith, J. N.; Eisele, F. L.; McMurry, P. H.

    2002-12-01

    Understanding new particle formation in the atmosphere depends upon many factors including detailed knowledge of their chemical composition. The chemical composition of sub-20 nanometer ambient aerosol particles, however, is typically inferred from observations of the aerosol behavior when subjected to varying conditions during sampling. Direct observations of aerosol chemical composition are usually limited to or dominated by larger particles of higher mass. Recently a new instrument has been developed - the Thermal Desorption Chemical Ionization Mass Spectrometer (TDCIMS) - which can directly measure the chemical composition of sub-20 nanometer aerosol particles. Briefly, the front end of the TDCIMS functions as an electrostatic precipitator using a strong electric field to collect charged aerosol particles onto a sample wire. After volatilization by heating, the component species of the collected particles are subjected to chemical ionization prior to introduction into the mass spectrometer for analysis. Detection limits on the order of picograms permit sample collection periods as small as five minutes for ambient aerosol concentrations providing near "real-time" resolution. For selected periods from April through June 2002, we used the TDCIMS to measure the chemical composition of ambient aerosol for the first time. We investigated both the positive and negative ion spectrums produced by sub-20 nanometer ambient aerosol particles at the National Center for Atmospheric Research in Boulder, Colorado. Principal species identified include ammonium, sulfate and nitrate although additional peaks consistent with particle-phase origin were readily observed. Diurnal concentration profiles appear to be present and the relative proportion of sulfate and nitrate to each other can vary appreciably over several hours and between days. Validation of the TDCIMS' performance and the interpretation of its results will also be discussed.

  16. RADIOCARBON MEASUREMENTS ON PM-2.5 AMBIENT AEROSOL

    EPA Science Inventory

    Radiocarbon (14C) measurements provide an estimate of the fraction of carbon in a sample that is biogenic. The methodology has been extensively used in past wintertime studies to quantify the contribution of wood smoke to ambient aerosol. In summertime such measurements can p...

  17. Uptake of Ambient Organic Gases to Acidic Sulfate Aerosols

    NASA Astrophysics Data System (ADS)

    Liggio, J.; Li, S.

    2009-05-01

    The formation of secondary organic aerosols (SOA) in the atmosphere has been an area of significant interest due to its climatic relevance, its effects on air quality and human health. Due largely to the underestimation of SOA by regional and global models, there has been an increasing number of studies focusing on alternate pathways leading to SOA. In this regard, recent work has shown that heterogeneous and liquid phase reactions, often leading to oligomeric material, may be a route to SOA via products of biogenic and anthropogenic origin. Although oligomer formation in chamber studies has been frequently observed, the applicability of these experiments to ambient conditions, and thus the overall importance of oligomerization reactions remain unclear. In the present study, ambient air is drawn into a Teflon smog chamber and exposed to acidic sulfate aerosols which have been formed in situ via the reaction of SO3 with water vapor. The aerosol composition is measured with a High Resolution Aerodyne Aerosol Mass Spectrometer (HR-ToF-AMS), and particle size distributions are monitored with a scanning mobility particle sizer (SMPS). The use of ambient air and relatively low inorganic particle loading potentially provides clearer insight into the importance of heterogeneous reactions. Results of experiments, with a range of sulfate loadings show that there are several competing processes occurring on different timescales. A significant uptake of ambient organic gases to the particles is observed immediately followed by a slow shift towards higher m/z over a period of several hours indicating that higher molecular weight products (possibly oligomers) are being formed through a reactive process. The results suggest that heterogeneous reactions can occur with ambient organic gases, even in the presence of ammonia, which may have significant implications to the ambient atmosphere where particles may be neutralized after their formation.

  18. 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

  19. ISS Ambient Air Quality: Updated Inventory of Known Aerosol Sources

    NASA Technical Reports Server (NTRS)

    Meyer, Marit

    2014-01-01

    Spacecraft cabin air quality is of fundamental importance to crew health, with concerns encompassing both gaseous contaminants and particulate matter. Little opportunity exists for direct measurement of aerosol concentrations on the International Space Station (ISS), however, an aerosol source model was developed for the purpose of filtration and ventilation systems design. This model has successfully been applied, however, since the initial effort, an increase in the number of crewmembers from 3 to 6 and new processes on board the ISS necessitate an updated aerosol inventory to accurately reflect the current ambient aerosol conditions. Results from recent analyses of dust samples from ISS, combined with a literature review provide new predicted aerosol emission rates in terms of size-segregated mass and number concentration. Some new aerosol sources have been considered and added to the existing array of materials. The goal of this work is to provide updated filtration model inputs which can verify that the current ISS filtration system is adequate and filter lifetime targets are met. This inventory of aerosol sources is applicable to other spacecraft, and becomes more important as NASA considers future long term exploration missions, which will preclude the opportunity for resupply of filtration products.

  20. Ambient aerosol analysis using aerosol-time-of-flight mass spectrometry

    SciTech Connect

    Prather, K.A.; Noble, C.A.; Liu, D.Y.; Silva, P.J.; Fergenson, D.F.

    1996-10-01

    We have recently developed a technique, Aerosol-Time-of-Flight Mass Spectrometry (ATOFMS), which is capable of real-time determination of the aerodynamic size and chemical composition of individual aerosol particles. In order to obtain such information, the techniques of aerodynamic particle sizing and time-of-flight mass spectrometry are combined in a single instrument. ATOFMS is being used for the direct analysis of ambient aerosols with the goal of establishing correlations between particle size and chemical composition. Currently, measurements are being made to establish potential links between the presence of particular types of particles with such factors as the time of day, weather conditions, and concentration levels of gaseous smog components such as NO{sub x} and ozone. This data will be used to help establish a better understanding of tropospheric gas-aerosol processes. This talk will discuss the operating principles of ATOFMS as well as present the results of ambient analysis studies performed in our laboratory.

  1. 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).

  2. Physical properties of ambient and laboratory-generated secondary organic aerosol

    NASA Astrophysics Data System (ADS)

    O'Brien, Rachel E.; Neu, Alexander; Epstein, Scott A.; MacMillan, Amanda C.; Wang, Bingbing; Kelly, Stephen T.; Nizkorodov, Sergey A.; Laskin, Alexander; Moffet, Ryan C.; Gilles, Mary K.

    2014-06-01

    The size and thickness of organic aerosol particles collected by impaction in five field campaigns were compared to those of laboratory-generated secondary organic aerosols (SOA). Scanning transmission X-ray microscopy was used to measure the total carbon absorbance (TCA) by individual particles as a function of their projection areas on the substrate. Particles with higher viscosity/surface tension can be identified by a steeper slope on a plot of TCA versus size because they flatten less upon impaction. The slopes of the ambient data are statistically similar indicating a small range of average viscosities/surface tensions across five field campaigns. Steeper slopes were observed for the plots corresponding to ambient particles, while smaller slopes were indicative of the laboratory-generated SOA. This comparison indicates that ambient organic particles have higher viscosities/surface tensions than those typically generated in laboratory SOA studies.

  3. Physical Properties of Ambient and Laboratory-Generated Secondary Organic Aerosol

    SciTech Connect

    O'Brien, Rachel E.; Neu, Alexander; Epstein, Scott A.; MacMillan, Amanda; Wang, Bingbing; Kelly, Stephen T.; Nizkorodov, Sergey; Laskin, Alexander; Moffet, Ryan C.; Gilles, Mary K.

    2014-06-17

    The size and thickness of organic aerosol particles collected by impaction in five field campaigns were compared to those of laboratory generated secondary organic aerosols (SOA). Scanning transmission x-ray microscopy (STXM) was used to measure the total carbon absorbance (TCA) by individual particles as a function of their projection areas on the substrate. Because they flatten less upon impaction, particles with higher viscosity and surface tension can be identified by a steeper slope on a plot of TCA vs. size. The slopes of the ambient data are statistically similar indicating a small range of average viscosities and surface tensions across five field campaigns. Steeper slopes were observed for the plots corresponding to ambient particles, while smaller slopes were indicative of the laboratory generated SOA. This comparison indicates that ambient organic particles have higher viscosities and surface tensions than those typically generated in laboratory SOA studies.

  4. An analysis of the meteorological parameters affecting ambient concentrations of acid aerosols in Uniontown, Pennsylvania

    NASA Astrophysics Data System (ADS)

    Zelenka, Michael P.

    Ambient concentrations of aerosol strong acidity (H +) that were collected in Uniontown, Pennsylvania, during the summer of 1990 were evaluated to determine the relationships between meteorology and the magnitude of the H + concentrations. An extensive database containing 17 meteorological parameters was compiled for the Uniontown - Pittsburgh region. The database included both surface and upper air meteorological parameters. Concentrations of ambient acid sulfate aerosols collected in Uniontown, Pennsylvania, in the summer of 1990 were greatly affected by both local and regional meteorological conditions. Seven distinct meteorological synoptic types or regimes were identified for the summer months. A clear association was shown between episodic events of elevated ambient H + concentrations and one of the regimes, referred to here as synoptic type 5, which occurred when an anticyclone set up to the east of the mid-Atlantic states. Much of the variability (approximately 45%) in H + concentrations for the overall model was explained by the surface air temperature. Approximately 10% of the H' variability was explained by westerly winds as expressed by the U components of the morning 850 mb wind and the mean daily surface wind at Uniontown. Results showed that for days under the influence of synoptic type 5, which was associated with the highest levels of ambient H', the surface temperature explained approximately one-third of the variability in H' concentrations. The height of the mixing layer also affected the variability in H + concentrations, accounting for nearly a quarter of the variance. These results show that an analysis of the surface wind speed and direction alone will not adequately explain the variability in the concentrations of ambient acid aerosols. Analyses of the meteorological parameters affecting ambient concentrations of acid aerosols should include the mixing height, as well as the temperature, wind speed, and wind direction; both at the surface

  5. Separating Hazardous Aerosols from Ambient Aerosols: Role of Fluorescence-Spectral Determination, Aerodynamic Deflector and Pulse Aerodynamic Localizer (PAL)

    SciTech Connect

    Pan, Yong-Le; Cobler, Patrick J.; Rhodes, Scott A.; Halverson, Justin; Chang, Richard K.

    2005-08-22

    An aerosol deflection technique based on the single-shot UV-laser-induced fluorescence spectrum from a flowing particle is presented as a possible front-end bio-aerosol/hazardous-aerosol sensor/identifier. Cued by the fluorescence spectra, individual flowing bio-aerosol particles (1-10 {micro}m in diameter) have been successfully deflected from a stream of ambient aerosols. The electronics needed to compare the fluorescence spectrum of a particular particle with that of a pre-determined fluorescence spectrum are presented in some detail. The deflected particles, with and without going through a funnel for pulse aerodynamic localization (PAL), were collected onto a substrate for further analyses. To demonstrate how hazardous materials can be deflected, TbCl{sub 3} {center_dot} 6H{sub 2}O (a simulant material for some chemical forms of Uranium Oxide) aerosol particles (2 {micro}m in diameter) mixed with Arizona road dust was separated and deflected with our system.

  6. Measurements and Modeling of Aerosol Absorption and Single Scattering Albedo at Ambient Relative Hum

    NASA Technical Reports Server (NTRS)

    Redemann, J.; Russell, P. B.; Hamill, P.

    2000-01-01

    assumption then enters the estimate of the single scattering albedo at ambient relative humidity. To investigate the validity of this assumption we have carried out modeling studies of the absorption humidification factor, assuming that the aerosols contain an insoluble soot core and a coating which determines its hygroscopic growth behavior. The aerosol optical properties are then computed on the basis of the shell/core particle morphology using a Mie-code for concentric shells. From basic physical principles, it is conceivable that aerosol absorption increases when an atmospheric aerosol particle collects a non-absorbing shell, since the soot core is then exposed to an increased (focused) electric field strength. Indeed, our preliminary modeling studies show that the absorption of an atmospheric aerosol particle composed of a soot core and an aqueous sulfuric acid shell may increase by a factor of 50% due to a change in ambient relative humidity from 30 to 95%. We will show how this increased absorption is a function of the initial particle size and soot mass fraction.

  7. Ambient aerosol analysis using aerosol-time-of-flight mass spectrometry

    SciTech Connect

    Prather, K.A.; Noble, C.; Salt, K.; Nordmeyer, T.; Fergenson, D.; Morrical, B.

    1995-12-31

    Particulate pollution is an area of growing concern in light of recent studies which suggest a link between high concentrations of ambient PM{sub 10} (particles with diameters equal to or less than 10 {mu}m) and adverse health effects ranging from respiratory ailments to premature death. However, analytical chemistry techniques aimed at sampling and analysis of atmospheric aerosols are extremely limited in comparison to the number of methods that exist for studying gas phase smog components. As a result, current government regulations for levels of ambient particulates are necessarily general, lacking any chemical specificity. The authors have recently developed a technique, Aerosol-Time-of-Flight Mass Spectrometry (ATOFMS), which is capable of real-time determination of the size and chemical composition of individual aerosol particles. In order to obtain such information, the techniques of aerodynamic particle sizing and time-of-flight spectrometry are combined in a single instrument. In one of the aerosol studies performed in this laboratory, this instrument is being used for the direct analysis of ambient aerosols with the goal of establishing correlations between particle size and chemical composition. To date, the authors have observed very distinct size/composition correlations for organic and inorganic particles.

  8. Evidence for the existence of organosulfates from beta-pinene ozonolysis in ambient secondary organic aerosol.

    PubMed

    Iinuma, Yoshiteru; Müller, Conny; Berndt, Torsten; Böge, Olaf; Claeys, Magda; Herrmann, Hartmut

    2007-10-01

    The formation of organosulfates from the gas-phase ozonolysis of beta-pinene in the presence of neutral or acidic sulfate particles was investigated in a series of indoor aerosol chamber experiments. The organosulfates were analyzed using high-performance liquid chromatography (LC) coupled to electrospray ionization-time-of-flight mass spectrometry (MS) in parallel to ion trap MS. Organosulfates were only found in secondary organic aerosol from beta-pinene ozonolysis in the presence of acidic sulfate seed particles. One of the detected organosulfates also occurred in ambient aerosol samples that were collected at a forest site in northeastern Bavaria, Germany. beta-Pinene oxide, an oxidation product in beta-pinene/O3 and beta-pinene/NO3 reactions, is identified as a possible precursor for the beta-pinene-derived organosulfate. Furthermore, several nitroxy-organosulfates originating from monoterpenes were found in the ambient samples. These nitroxy-organosulfates were only detected in the nighttime samples, suggesting a role for nighttime chemistry in their formation. Their LC/MS chromatographic peak intensities suggest that they represent an important fraction of the organic mass in ambient aerosols, especially at night.

  9. Anomalous telephotometer results for the ambient atmospheric aerosol

    NASA Astrophysics Data System (ADS)

    Harrison, A. W.; Coombes, C. A.

    Simultaneous measurements of the ambient atmospheric aerosol scattering coefficient using a telephotometer δa( λ) and an integrating nephelometer δn( λ) have revealed a seasonal variation in the difference δn( λ) - δa( λ). This variation can be explained by the presence of terpene oil droplets in the boundary layer in the telephotometer line of sight but beyond the telephotometer target. The droplets are due to extensive fir and pine in that far region. A satisfactory modification of the original Koschmeider contrast theory to take account of this effect is outlined.

  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. Single-particle speciation of alkylamines in ambient aerosol at five European sites.

    PubMed

    Healy, Robert M; Evans, Greg J; Murphy, Michael; Sierau, Berko; Arndt, Jovanna; McGillicuddy, Eoin; O'Connor, Ian P; Sodeau, John R; Wenger, John C

    2015-08-01

    Alkylamines are associated with both natural and anthropogenic sources and have been detected in ambient aerosol in a variety of environments. However, little is known about the ubiquity or relative abundance of these species in Europe. In this work, ambient single-particle mass spectra collected at five sampling sites across Europe have been analysed for their alkylamine content. The aerosol time-of-flight mass spectrometer (ATOFMS) data used were collected in Ireland (Cork), France (Paris, Dunkirk and Corsica) and Switzerland (Zurich) between 2008 and 2013. Each dataset was queried for mass spectral marker ions associated with the following ambient alkylamines: dimethylamine (DMA), trimethylamine (TMA), diethylamine (DEA), triethylamine (TEA), dipropylamine (DPA) and tripropylamine (TPA). The fraction of ambient particles that contained detectable alkylamines ranged from 1 to 17 % depending on location, with the highest fractions observed in Paris and Zurich in the winter months. The lowest fractions were observed at coastal sites, where the influence of animal husbandry-related alkylamine emissions is also expected to be lowest. TMA was the most ubiquitous particle phase alkylamine detected and was observed at all locations. Alkylamines were found to be internally mixed with both sulphate and nitrate for each dataset, suggesting that aminium salt formation may be important at all sites investigated. Interestingly, in Corsica, all alkylamine particles detected were also found to be internally mixed with methanesulphonic acid (MSA), indicating that aminium methanesulphonate salts may represent a component of marine ambient aerosol in the summer months. Internal mixing of alkylamines with sea salt was not observed, however. Alkylamine-containing particle composition was found to be reasonably homogeneous at each location, with the exception of the Corsica and Dunkirk sites, where two and four distinct mixing states were observed, respectively.

  12. Speciation of Fe in ambient aerosol and cloudwater

    SciTech Connect

    Siefert, L.

    1996-08-15

    Atmospheric iron (Fe) is thought to play an important role in cloudwater chemistry (e.g., S(IV) oxidation, oxidant production, etc.), and is also an important source of Fe to certain regions of the worlds oceans where Fe is believed to be a rate-limiting nutrient for primary productivity. This thesis focuses on understanding the chemistry, speciation and abundance of Fe in cloudwater and aerosol in the troposphere, through observations of Fe speciation in the cloudwater and aerosol samples collected over the continental United States and the Arabian Sea. Different chemical species of atmospheric Fe were measured in aerosol and cloudwater samples to help assess the role of Fe in cloudwater chemistry.

  13. Variability of Ambient Aerosol in the Mexico City Metropolian Area

    NASA Astrophysics Data System (ADS)

    Onasch, T. B.; Worsnop, D. R.; Canagaratna, M.; Jayne, J. T.; Herndon, S.; Mortimer, P.; Kolb, C. E.; Rogers, T.; Knighton, B.; Dunlea, E.; Marr, L.; de Foy, B.; Molina, M.; Molina, L.; Salcedo, D.; Dzepina, K.; Jimenez, J. L.

    2004-12-01

    The spatial and temporal variations of the ambient aerosol in the Mexico City Metropolitan area was characterized during the springs of 2002 and 2003 using a mobile laboratory equipped with gas and particulate measurement instrumentation. The laboratory was operated at various fixed sites locations in and at the edge of the metropolitan area (Xalostoc, Merced, Cenica, Pedregal, and Santa Ana). Size-resolved aerosol mass and chemical composition was measured with an aerosol mass spectrometer and selected trace gas species (low mass organic compounds, NO, NO2, NOy, O3, SO2, CH2O, NH3, CO2) were measured using a proton transfer reaction mass spectrometer and various optical systems. The aerosol was predominantly organic in composition with lesser amounts of ammonium nitrate, sulfate, and chloride. The organic component was composed of mixed primary and secondary organic compounds. The mass loading and chemical composition of the aerosol was influenced by local and regional air pollution sources and the meteorology in Mexico City. Most urban sites were influenced by a strong diurnal particulate mass trend indicative of primary organic emissions from traffic during early morning and subsequently oxidized/processed organics and ammonium nitrate particles starting in the mid-morning (~9 AM) and continuing throughout the day. Morning traffic-related primary organic emissions were strongest at La Merced (center of Mexico City, located near a busy food market), more subdued at other fixed sites further from the city center, and varied depending upon the day of week and holiday schedules. Particle-bound polycyclic aromatic hydrocarbons were observed within Mexico City fixed sites and were correlated with traffic organic PM emissions. Oxidized organic and ammonium nitrate events occurred during mid-morning at all city sites and were well correlated with gas phase photochemical activity. The daily ammonium nitrate aerosol event occurred later at sites near the city limits

  14. Characterisation of regional ambient biomass burning organic aerosol mixing ratios

    NASA Astrophysics Data System (ADS)

    Jolleys, M.; Coe, H.; McFiggans, G.; Capes, G.; Allan, J. D.; Crosier, J.; Williams, P.; Allen, G.; Bower, K.; Jimenez, J. L.; Russell, L. M.; Grutter, M.; Baumgardner, D.

    2012-12-01

    No evidence for a regional additional source of secondary organic aerosol (SOA) has been identified in measurements of biomass burning-influenced ambient air masses. Measurements included in this study were obtained from the deployment of an Aerodyne Quadrupole Aerosol Mass Spectrometer during four field campaigns, involving both research aircraft flights and ground-based measurements. OA concentrations normalised to excess CO (OA/dCO) show strong regional and local scale variability, with a difference of almost a factor of five across fresh OA emissions between campaigns. Average OA/dCO is typically higher in the near-field than at a greater distance from source, indicating an absence of significant SOA formation, despite evidence to suggest OA becomes increasingly oxidized with age. This trend is in contrast with observations of anthropogenic OA in urban environments, where OA/dCO is consistently shown to increase with distance from source. There is no such agreement in the case of biomass burning OA (BBOA) amongst the literature base, with conflicting examples relating to the influence of SOA on aerosol loadings. A wide range of average initial emission ratios (ERs) close to source are observed both within the datasets analysed here and within the literature, together with considerable variability in individual OA/dCO values throughout fresh biomass burning plumes. The extent of this variability far outweighs any increase in OA/dCO in the few instances it is observed here, suggesting that source conditions are of greater importance for the propagation of BBOA loadings within the ambient atmosphere. However, the implications of ageing on OA/dCO variability appear to be highly uncertain, with little consistency between observed trends for different locations. Furthermore, the exact effects of the fire conditions influencing emissions from biomass burning events remain poorly constrained. These uncertainties regarding the evolution of biomass burning emissions

  15. Studies of Ambient and Chamber Aerosol Composition using the Aerosol Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Craven, Jill Suzanne

    This thesis presents composition measurements for atmospherically relevant inorganic and organic aerosol from laboratory and ambient measurements using the Aerodyne aerosol mass spectrometer. Studies include the oxidation of dodecane in the Caltech environmental chambers, and several aircraft- and ground-based field studies, which include the quantification of wildfire emissions off the coast of California, and Los Angeles urban emissions. The oxidation of dodecane by OH under low NO conditions and the formation of secondary organic aerosol (SOA) was explored using a gas-phase chemical model, gas-phase CIMS measurements, and high molecular weight ion traces from particlephase HR-TOF-AMS mass spectra. The combination of these measurements support the hypothesis that particle-phase chemistry leading to peroxyhemiacetal formation is important. Positive matrix factorization (PMF) was applied to the AMS mass spectra which revealed three factors representing a combination of gas-particle partitioning, chemical conversion in the aerosol, and wall deposition. Airborne measurements of biomass burning emissions from a chaparral fire on the central Californian coast were carried out in November 2009. Physical and chemical changes were reported for smoke ages 0--4 h old. CO 2 normalized ammonium, nitrate, and sulfate increased, whereas the normalized OA decreased sharply in the first 1.5--2 h, and then slowly increased for the remaining 2 h (net decrease in normalized OA). Comparison to wildfire samples from the Yucatan revealed that factors such as relative humidity, incident UV radiation, age of smoke, and concentration of emissions are important for wildfire evolution. Ground-based aerosol composition is reported for Pasadena, CA during the sumix mer of 2009. The OA component, which dominated the submicron aerosol mass, was deconvolved into hydrocarbon-like organic aerosol (HOA), semi-volatile oxidized organic aerosol (SVOOA), and low-volatility oxidized organic aerosol

  16. Miniature instruments for aerosol extinction at ambient conditions

    NASA Astrophysics Data System (ADS)

    Murphy, D. M.

    2015-12-01

    Aerosol extinction is a fundamental parameter for the direct forcing of climate, visibility, and comparisons to remote sensing. Bringing air into an instrument "box" almost always changes the relative humidity and loses some dust or other large particles. I will show two techniques for miniature instruments that measure extinction at ambient conditions. One is a miniature sun photometer for vertical profiles. In the last year it has successfully gathered data on test flights with excellent performance and signal to noise. The second instrument is a miniature cavity ring down instrument open to the air. In both cases, small instruments require decisions about just what is necessary for the measurement rather than just scaling down larger designs. I will explore the rationale for some of these design choices.

  17. Quantitative estimates of the volatility of ambient organic aerosol

    NASA Astrophysics Data System (ADS)

    Cappa, C. D.; Jimenez, J. L.

    2010-01-01

    Measurements of the sensitivity of organic aerosol (OA, and its components) mass to changes in temperature were recently reported by Huffman et al. (2009) using a tandem thermodenuder-aerosol mass spectrometer (TD-AMS) system in Mexico City and the Los Angeles area. Here, we use these measurements to derive quantitative estimates of aerosol volatility within the framework of absorptive partitioning theory using a kinetic model of aerosol evaporation in the TD. OA volatility distributions (or "basis-sets") are determined using several assumptions as to the enthalpy of vaporization (ΔHvap). We present two definitions of "non-volatile OA," one being a global and one a local definition. Based on these definitions, our analysis indicates that a substantial fraction of the organic aerosol is comprised of non-volatile components that will not evaporate under any atmospheric conditions, on the order of 50-80% when the most realistic ΔHvap assumptions are considered. The sensitivity of the total OA mass to dilution and ambient changes in temperature has been assessed for the various ΔHvap assumptions. The temperature sensitivity is relatively independent of the particular ΔHvap assumptions whereas dilution sensitivity is found to be greatest for the low (ΔHvap = 50 kJ/mol) and lowest for the high (ΔHvap = 150 kJ/mol) assumptions. This difference arises from the high ΔHvap assumptions yielding volatility distributions with a greater fraction of non-volatile material than the low ΔHvap assumptions. If the observations are fit using a 1 or 2-component model the sensitivity of the OA to dilution is unrealistically high. An empirical method introduced by Faulhaber et al. (2009) has also been used to independently estimate a volatility distribution for the ambient OA and is found to give results consistent with the high and variable ΔHvap assumptions. Our results also show that the amount of semivolatile gas-phase organics in equilibrium with the OA could range from ~20

  18. Quantitative estimates of the volatility of ambient organic aerosol

    NASA Astrophysics Data System (ADS)

    Cappa, C. D.; Jimenez, J. L.

    2010-06-01

    Measurements of the sensitivity of organic aerosol (OA, and its components) mass to changes in temperature were recently reported by Huffman et al.~(2009) using a tandem thermodenuder-aerosol mass spectrometer (TD-AMS) system in Mexico City and the Los Angeles area. Here, we use these measurements to derive quantitative estimates of aerosol volatility within the framework of absorptive partitioning theory using a kinetic model of aerosol evaporation in the TD. OA volatility distributions (or "basis-sets") are determined using several assumptions as to the enthalpy of vaporization (ΔHvap). We present two definitions of "non-volatile OA," one being a global and one a local definition. Based on these definitions, our analysis indicates that a substantial fraction of the organic aerosol is comprised of non-volatile components that will not evaporate under any atmospheric conditions; on the order of 50-80% when the most realistic ΔHvap assumptions are considered. The sensitivity of the total OA mass to dilution and ambient changes in temperature has been assessed for the various ΔHvap assumptions. The temperature sensitivity is relatively independent of the particular ΔHvap assumptions whereas dilution sensitivity is found to be greatest for the low (ΔHvap = 50 kJ/mol) and lowest for the high (ΔHvap = 150 kJ/mol) assumptions. This difference arises from the high ΔHvap assumptions yielding volatility distributions with a greater fraction of non-volatile material than the low ΔHvap assumptions. If the observations are fit using a 1 or 2-component model the sensitivity of the OA to dilution is unrealistically high. An empirical method introduced by Faulhaber et al. (2009) has also been used to independently estimate a volatility distribution for the ambient OA and is found to give results consistent with the high and variable ΔHvap assumptions. Our results also show that the amount of semivolatile gas-phase organics in equilibrium with the OA could range from ~20

  19. Biogenic contribution to PM-2.5 ambient aerosol from radiocarbon measurements

    NASA Astrophysics Data System (ADS)

    Lewis, C.; Klouda, G.; Ellenson, W.

    2003-04-01

    Knowledge of the relative contributions of biogenic versus anthropogenic sources to ambient aerosol is of great interest in the formulation of strategies to achieve nationally mandated air quality standards. Radiocarbon (14C) measurements provide a means to quantify the biogenic fraction of any carbon-containing sample of ambient aerosol. In the absence of an impact from biomass burning (e.g., during summertime) such measurements can provide an estimate of the contribution of biogenic secondary organic aerosol, from biogenic volatile organic compound precursors. Radiocarbon results for 11.5-h PM-2.5 samples collected near Nashville, Tennessee, USA, during summer 1999 will be presented. On average the measured biogenic fraction was surprisingly large (more than half), with the average biogenic fraction for night samples being only slightly smaller than for day samples. Discussion will include (a) description of the radiocarbon methodology, (b) use of radiocarbon measurements on local vegetation and fuel samples as calibration data, (c) concurrent measurements of organic carbon and elemental carbon ambient concentrations, (d) assessment of organic aerosol sampling artifact through use of organic vapor denuders, variable face velocities, and filter extraction, and (e) comparison with published radiocarbon results obtained in Houston, Texas in a similar study. Disclaimer: This work has been funded wholly or in part by the United States Environmental Protection Agency under Interagency Agreement No. 13937923 to the National Institute of Standards and Technology, and Contract No. 68-D5-0049 to ManTech Environmental Tecnology, Inc. It has been subjected to Agency review and approved for publication.

  20. The application of an improved gas and aerosol collector for ambient air pollutants in China

    NASA Astrophysics Data System (ADS)

    Dong, Huabin; Zeng, Limin; Zhang, Yuanhang; Hu, Min; Wu, Yusheng

    2016-04-01

    An improved Gas and Aerosol Collector (GAC) equipped with a newly designed aerosol collector and a set of dull-polished wet annular denuder (WAD) was developed by Peking University based on a Steam Jet Aerosol Collector (SJAC) sampler. Combined with Ion Chromatography (IC) the new sampler performed well in laboratory tests with high collection efficiencies for SO2 (above 98 %) and particulate sulfate (as high as 99.5 %). An inter-comparison between the GAC-IC system and the filter-pack method was performed and the results indicated that the GAC-IC system could supply reliable particulate sulfate, nitrate, chloride, and ammonium data in field measurement with a much wider range of ambient concentrations. From 2008 to 2015, dozens of big field campaigns (rural and coastal sites) were executed in different parts of China, the GAC-IC system took the chance having its field measurement performance checked repeatedly and provided high quality data in ambient conditions either under high loadings of pollutants or background area. Its measurements were highly correlated with data by other commercial instruments such as the SO2 analyzer, the HONO analyzer, a filter sampler, Aerosol Mass Spectrometer (AMS), etc. over a wide range of concentrations and proved particularly useful in future intensive campaigns or long-term monitoring stations to study various environmental issues such as secondary aerosol and haze formation. During these years of applications of GAC-IC in those field campaigns, we found some problems of several instruments running under field environment and some interesting results could also be drew from the large amount of data measured in near 20 provinces of China. Detail results will be demonstrated on the poster afterwards.

  1. An intercomparison study of analytical methods used for quantification of levoglucosan in ambient aerosol filter samples

    NASA Astrophysics Data System (ADS)

    Yttri, K. E.; Schnelle-Kreis, J.; Maenhaut, W.; Abbaszade, G.; Alves, C.; Bjerke, A.; Bonnier, N.; Bossi, R.; Claeys, M.; Dye, C.; Evtyugina, M.; García-Gacio, D.; Hillamo, R.; Hoffer, A.; Hyder, M.; Iinuma, Y.; Jaffrezo, J.-L.; Kasper-Giebl, A.; Kiss, G.; López-Mahia, P. L.; Pio, C.; Piot, C.; Ramirez-Santa-Cruz, C.; Sciare, J.; Teinilä, K.; Vermeylen, R.; Vicente, A.; Zimmermann, R.

    2015-01-01

    The monosaccharide anhydrides (MAs) levoglucosan, galactosan and mannosan are products of incomplete combustion and pyrolysis of cellulose and hemicelluloses, and are found to be major constituents of biomass burning (BB) aerosol particles. Hence, ambient aerosol particle concentrations of levoglucosan are commonly used to study the influence of residential wood burning, agricultural waste burning and wildfire emissions on ambient air quality. A European-wide intercomparison on the analysis of the three monosaccharide anhydrides was conducted based on ambient aerosol quartz fiber filter samples collected at a Norwegian urban background site during winter. Thus, the samples' content of MAs is representative for BB particles originating from residential wood burning. The purpose of the intercomparison was to examine the comparability of the great diversity of analytical methods used for analysis of levoglucosan, mannosan and galactosan in ambient aerosol filter samples. Thirteen laboratories participated, of which three applied high-performance anion-exchange chromatography (HPAEC), four used high-performance liquid chromatography (HPLC) or ultra-performance liquid chromatography (UPLC) and six resorted to gas chromatography (GC). The analytical methods used were of such diversity that they should be considered as thirteen different analytical methods. All of the thirteen laboratories reported levels of levoglucosan, whereas nine reported data for mannosan and/or galactosan. Eight of the thirteen laboratories reported levels for all three isomers. The accuracy for levoglucosan, presented as the mean percentage error (PE) for each participating laboratory, varied from -63 to 20%; however, for 62% of the laboratories the mean PE was within ±10%, and for 85% the mean PE was within ±20%. For mannosan, the corresponding range was -60 to 69%, but as for levoglucosan, the range was substantially smaller for a subselection of the laboratories; i.e. for 33% of the

  2. An intercomparison study of analytical methods used for quantification of levoglucosan in ambient aerosol filter samples

    NASA Astrophysics Data System (ADS)

    Yttri, K. E.; Schnelle-Kreiss, J.; Maenhaut, W.; Alves, C.; Bossi, R.; Bjerke, A.; Claeys, M.; Dye, C.; Evtyugina, M.; García-Gacio, D.; Gülcin, A.; Hillamo, R.; Hoffer, A.; Hyder, M.; Iinuma, Y.; Jaffrezo, J.-L.; Kasper-Giebl, A.; Kiss, G.; López-Mahia, P. L.; Pio, C.; Piot, C.; Ramirez-Santa-Cruz, C.; Sciare, J.; Teinilä, K.; Vermeylen, R.; Vicente, A.; Zimmermann, R.

    2014-07-01

    The monosaccharide anhydrides (MAs) levoglucosan, galactosan and mannosan are products of incomplete combustion and pyrolysis of cellulose and hemicelluloses, and are found to be major constituents of biomass burning aerosol particles. Hence, ambient aerosol particle concentrations of levoglucosan are commonly used to study the influence of residential wood burning, agricultural waste burning and wild fire emissions on ambient air quality. A European-wide intercomparison on the analysis of the three monosaccharide anhydrides was conducted based on ambient aerosol quartz fiber filter samples collected at a Norwegian urban background site during winter. Thus, the samples' content of MAs is representative for biomass burning particles originating from residential wood burning. The purpose of the intercomparison was to examine the comparability of the great diversity of analytical methods used for analysis of levoglucosan, mannosan and galactosan in ambient aerosol filter samples. Thirteen laboratories participated, of which three applied High-Performance Anion-Exchange Chromatography (HPAEC), four used High-Performance Liquid Chromatography (HPLC) or Ultra-Performance Liquid Chromatography (UPLC), and six resorted to Gas Chromatography (GC). The analytical methods used were of such diversity that they should be considered as thirteen different analytical methods. All of the thirteen laboratories reported levels of levoglucosan, whereas nine reported data for mannosan and/or galactosan. Eight of the thirteen laboratories reported levels for all three isomers. The accuracy for levoglucosan, presented as the mean percentage error (PE) for each participating laboratory, varied from -63 to 23%; however, for 62% of the laboratories the mean PE was within ±10%, and for 85% the mean PE was within ±20%. For mannosan, the corresponding range was -60 to 69%, but as for levoglucosan, the range was substantially smaller for a subselection of the laboratories; i.e., for 33% of

  3. Inhalation Exposure and Lung Dose Analysis of Multi-mode Complex Ambient Aerosols

    EPA Science Inventory

    Rationale: Ambient aerosols are complex mixture of particles with different size, shape and chemical composition. Although they are known to cause health hazard, it is not fully understood about causal mechanisms and specific attributes of particles causing the effects. Internal ...

  4. BIOGENIC CONTRIBUTION TO PM-2.5 AMBIENT AEROSOL FROM RADIOCARBON MEASUREMENTS

    EPA Science Inventory

    Knowledge of the relative contributions of biogenic versus anthropogenic sources to ambient aerosol is of great interest in the formulation of strategies to achieve nationally mandated air quality standards. Radiocarbon (Carbon-14) measurements provide a means to quantify the ...

  5. ANALYSIS OF RESPIRATORY DESPOSITION DOSE OF INHALED AMBIENT AEROSOLS FOR DIFFERENT SIZE FRACTIONS

    EPA Science Inventory

    ANALYSIS OF RESPIRATORY DEPOSITION DOSE OF INHALED AMBIENT AEROSOLS FOR DIFFERENT SIZE FRACTIONS. Chong S. Kim, SC. Hu**, PA Jaques*, US EPA, National Health and Environmental Effects Research Laboratory, Research Triangle Park, NC 27711; **IIT Research Institute, Chicago, IL; *S...

  6. Development and first application of an Aerosol Collection Module (ACM) for quasi online compound specific aerosol measurements

    NASA Astrophysics Data System (ADS)

    Hohaus, Thorsten; Kiendler-Scharr, Astrid; Trimborn, Dagmar; Jayne, John; Wahner, Andreas; Worsnop, Doug

    2010-05-01

    Atmospheric aerosols influence climate and human health on regional and global scales (IPCC, 2007). In many environments organics are a major fraction of the aerosol influencing its properties. Due to the huge variety of organic compounds present in atmospheric aerosol current measurement techniques are far from providing a full speciation of organic aerosol (Hallquist et al., 2009). The development of new techniques for compound specific measurements with high time resolution is a timely issue in organic aerosol research. Here we present first laboratory characterisations of an aerosol collection module (ACM) which was developed to allow for the sampling and transfer of atmospheric PM1 aerosol. The system consists of an aerodynamic lens system focussing particles on a beam. This beam is directed to a 3.4 mm in diameter surface which is cooled to -30 °C with liquid nitrogen. After collection the aerosol sample can be evaporated from the surface by heating it to up to 270 °C. The sample is transferred through a 60cm long line with a carrier gas. In order to test the ACM for linearity and sensitivity we combined it with a GC-MS system. The tests were performed with octadecane aerosol. The octadecane mass as measured with the ACM-GC-MS was compared versus the mass as calculated from SMPS derived total volume. The data correlate well (R2 0.99, slope of linear fit 1.1) indicating 100 % collection efficiency. From 150 °C to 270 °C no effect of desorption temperature on transfer efficiency could be observed. The ACM-GC-MS system was proven to be linear over the mass range 2-100 ng and has a detection limit of ~ 2 ng. First experiments applying the ACM-GC-MS system were conducted at the Jülich Aerosol Chamber. Secondary organic aerosol (SOA) was formed from ozonolysis of 600 ppbv of b-pinene. The major oxidation product nopinone was detected in the aerosol and could be shown to decrease from 2 % of the total aerosol to 0.5 % of the aerosol over the 48 hours of

  7. Application of the VH-TDMA technique to coastal ambient aerosols

    NASA Astrophysics Data System (ADS)

    Johnson, G.; Ristovski, Z.; Morawska, L.

    2004-08-01

    A newly developed VH-TDMA has been used for the first time to measure the volatile fractions and post volatilization hygroscopic growth factors of ambient aerosols in the coastal marine and urban environments. The results are compared with comparable data for laboratory generated aerosols of known composition. Measurements conducted on coastal Aitken mode particles showed volatilization behavior similar to laboratory generated aerosols composed of methane sulfonic acid and ammonium sulfate. Measurements conducted on 60 nm particles during nucleation events contained a greater fraction of material with similar volatility to ammonium sulfate than was found at other times. These particles were hygroscopic but less so than pure ammonium sulfate. Measurements conducted in the Brisbane central business district during sea breeze conditions show similar behavior to the coastal aerosol, but with additional low volatility species. This aerosol may originate from urban sources or from marine particles acquiring additional secondary aerosol species during transport.

  8. A novel Aerosol-Into-Liquid Collector for online measurements of trace metal and elements in ambient particulate matter (PM)

    NASA Astrophysics Data System (ADS)

    Wang, Dongbin; Shafer, Martin; Schauer, James; Sioutas, Constantinos

    2015-04-01

    A novel monitor for online, in-situ measurement of several important metal species (i.e. Fe, Mn and Cr) in ambient fine and ultrafine particulate matter (PM) is developed based on a recent published high flow rate Aerosol-Into-Liquid Collector. This Aerosol-Into-Liquid Collector collects particles directly as highly concentrated slurry samples, and the concentrations of target metals in slurry samples are subsequently determined in a Micro Volume Flow Cell (MVFC) coupled with absorbance spectrophotometry to detect colored complexes coming from the reactions between target metals and specific reagents. Laboratory tests are conducted to evaluate the performance of the MVFC-absorbance system. The calibration curves of the system are determined using standard solutions prepared by serial dilution. As part of the evaluation, the effects of reaction time, reagent amount and interference on the system are also evaluated. Field evaluations of the online monitor will be performed to validate the ability of this new online sampler in near-continuous collection and measurements. Both laboratory and field evaluations of the novel monitor will indicate that it is an effective and valuable technology for PM collection and characterization of important metal species in ambient aerosols.

  9. Aqueous photooxidation of ambient Po Valley Italy air samples: Insights into secondary organic aerosol formation

    NASA Astrophysics Data System (ADS)

    Kirkland, J. R.; Lim, Y. B.; Sullivan, A. P.; Decesari, S.; Facchini, C.; Collett, J. L.; Keutsch, F. N.; Turpin, B. J.

    2012-12-01

    In this work, we conducted aqueous photooxidation experiments with ambient samples in order to develop insights concerning the formation of secondary organic aerosol through gas followed by aqueous chemistry (SOAaq). Water-soluble organics (e.g., glyoxal, methylglyoxal, glycolaldehyde, acetic acid, acetone) are formed through gas phase oxidation of alkene and aromatic emissions of anthropogenic and biogenic origin. Their further oxidation in clouds, fogs and wet aerosols can form lower volatility products (e.g., oligomers, organic acids) that remain in the particle phase after water evaporation, thus producing SOA. The aqueous OH radical oxidation of several individual potentially important precursors has been studied in the laboratory. In this work, we used a mist-chamber apparatus to collect atmospheric mixtures of water-soluble gases from the ambient air at San Pietro Capofiume, Italy during the PEGASOS field campaign. We measured the concentration dynamics after addition of OH radicals, in order to develop new insights regarding formation of SOA through aqueous chemistry. Specifically, batch aqueous reactions were conducted with 33 ml mist-chamber samples (TOC ~ 50-100μM) and OH radicals (~10-12M) in a new low-volume aqueous reaction vessel. OH radicals were formed in-situ, continuously by H2O2 photolysis. Products were analyzed by ion chromatography (IC), electrospray ionization mass spectrometry (ESI-MS +/-), and ESI-MS with IC pre-separation (IC/ESI-MS-). Reproducible formation of pyruvate and oxalate were observed both by IC and ESI-MS. These compounds are known to form from aldehyde oxidation in the aqueous phase. New insights regarding the aqueous chemistry of these "more atmospherically-realistic" experiments will be discussed.

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

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

    SciTech Connect

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

    2015-09-28

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

  12. Collection of Aerosolized Human Cytokines Using Teflon® Filters

    PubMed Central

    McKenzie, Jennifer H.; McDevitt, James J.; Fabian, M. Patricia; Hwang, Grace M.; Milton, Donald K.

    2012-01-01

    Background Collection of exhaled breath samples for the analysis of inflammatory biomarkers is an important area of research aimed at improving our ability to diagnose, treat and understand the mechanisms of chronic pulmonary disease. Current collection methods based on condensation of water vapor from exhaled breath yield biomarker levels at or near the detection limits of immunoassays contributing to problems with reproducibility and validity of biomarker measurements. In this study, we compare the collection efficiency of two aerosol-to-liquid sampling devices to a filter-based collection method for recovery of dilute laboratory generated aerosols of human cytokines so as to identify potential alternatives to exhaled breath condensate collection. Methodology/Principal Findings Two aerosol-to-liquid sampling devices, the SKC® Biosampler and Omni 3000™, as well as Teflon® filters were used to collect aerosols of human cytokines generated using a HEART nebulizer and single-pass aerosol chamber setup in order to compare the collection efficiencies of these sampling methods. Additionally, methods for the use of Teflon® filters to collect and measure cytokines recovered from aerosols were developed and evaluated through use of a high-sensitivity multiplex immunoassay. Our results show successful collection of cytokines from pg/m3 aerosol concentrations using Teflon® filters and measurement of cytokine levels in the sub-picogram/mL concentration range using a multiplex immunoassay with sampling times less than 30 minutes. Significant degradation of cytokines was observed due to storage of cytokines in concentrated filter extract solutions as compared to storage of dry filters. Conclusions Use of filter collection methods resulted in significantly higher efficiency of collection than the two aerosol-to-liquid samplers evaluated in our study. The results of this study provide the foundation for a potential new technique to evaluate biomarkers of inflammation in

  13. A direct method for e-cigarette aerosol sample collection.

    PubMed

    Olmedo, Pablo; Navas-Acien, Ana; Hess, Catherine; Jarmul, Stephanie; Rule, Ana

    2016-08-01

    E-cigarette use is increasing in populations around the world. Recent evidence has shown that the aerosol produced by e-cigarettes can contain a variety of toxicants. Published studies characterizing toxicants in e-cigarette aerosol have relied on filters, impingers or sorbent tubes, which are methods that require diluting or extracting the sample in a solution during collection. We have developed a collection system that directly condenses e-cigarette aerosol samples for chemical and toxicological analyses. The collection system consists of several cut pipette tips connected with short pieces of tubing. The pipette tip-based collection system can be connected to a peristaltic pump, a vacuum pump, or directly to an e-cigarette user for the e-cigarette aerosol to flow through the system. The pipette tip-based system condenses the aerosol produced by the e-cigarette and collects a liquid sample that is ready for analysis without the need of intermediate extraction solutions. We tested a total of 20 e-cigarettes from 5 different brands commercially available in Maryland. The pipette tip-based collection system condensed between 0.23 and 0.53mL of post-vaped e-liquid after 150 puffs. The proposed method is highly adaptable, can be used during field work and in experimental settings, and allows collecting aerosol samples from a wide variety of e-cigarette devices, yielding a condensate of the likely exact substance that is being delivered to the lungs.

  14. A direct method for e-cigarette aerosol sample collection.

    PubMed

    Olmedo, Pablo; Navas-Acien, Ana; Hess, Catherine; Jarmul, Stephanie; Rule, Ana

    2016-08-01

    E-cigarette use is increasing in populations around the world. Recent evidence has shown that the aerosol produced by e-cigarettes can contain a variety of toxicants. Published studies characterizing toxicants in e-cigarette aerosol have relied on filters, impingers or sorbent tubes, which are methods that require diluting or extracting the sample in a solution during collection. We have developed a collection system that directly condenses e-cigarette aerosol samples for chemical and toxicological analyses. The collection system consists of several cut pipette tips connected with short pieces of tubing. The pipette tip-based collection system can be connected to a peristaltic pump, a vacuum pump, or directly to an e-cigarette user for the e-cigarette aerosol to flow through the system. The pipette tip-based system condenses the aerosol produced by the e-cigarette and collects a liquid sample that is ready for analysis without the need of intermediate extraction solutions. We tested a total of 20 e-cigarettes from 5 different brands commercially available in Maryland. The pipette tip-based collection system condensed between 0.23 and 0.53mL of post-vaped e-liquid after 150 puffs. The proposed method is highly adaptable, can be used during field work and in experimental settings, and allows collecting aerosol samples from a wide variety of e-cigarette devices, yielding a condensate of the likely exact substance that is being delivered to the lungs. PMID:27200479

  15. RADIOCARBON MEASUREMENTS ON PM 2.5 AMBIENT AEROSOL FROM NASHVILLE, TN

    EPA Science Inventory

    Radiocarbon (Carbon-14) measurements provide an estimate of the fraction of carbon in a sample that is biogenic. The methodology has been extensively used in past wintertime studies to quantify the contribution of wood smoke to ambient aerosol. In summertime such measurements...

  16. ANALYSIS OF RESPIRATORY DEPOSITION OF INHALED AMBIENT AEROSOLS FOR DIFFERENT DOSE METRICS

    EPA Science Inventory

    ANALYSIS OF RESPIRATORY DEPOSITION OF INHALED AMBIENT AEROSOLS FOR DIFFERENT DOSE METRICS.
    Chong S. Kim, SC. Hu**, PA Jaques*, US EPA, National Health and Environmental Effects Research Laboratory, Research Triangle Park, NC 27711; **IIT Research Institute, Chicago, IL; *South...

  17. 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.

  18. Molecular Characterization of Free Tropospheric Aerosol Collected at the Pico Mountain Observatory

    NASA Astrophysics Data System (ADS)

    Dzepina, K.; Mazzoleni, C.; Fialho, P. J.; China, S.; Zhang, B.; Owen, R. C.; Helmig, D.; Jacques, H.; Kumar, S.; Perlinger, J. A.; Kramer, L. J.; Dziobak, M.; Ampadu, M.; Olsen, S. C.; Wuebbles, D. J.; Mazzoleni, L. R.

    2014-12-01

    Long-range transported free tropospheric aerosol was sampled at the Pico Mountain Observatory (38°28'15''N, 28°24'14''W; 2225 m amsl) on Pico Island of the Azores archipelago in the North Atlantic ~3900 km east and downwind of North America. Filter-collected aerosol during summer 2012 was analyzed for organic and elemental carbon, and inorganic ions. The average ambient concentration of aerosol was 0.9 μg m-3. Organic aerosol contributed the majority of mass (57%), followed by sulfate (21%) and nitrate (17%). Filter-collected aerosol was positively correlated with continuous aerosol measurements of black carbon, light scattering and number concentration. Water-soluble organic compounds (WSOC) from 9/24 and 9/25 aerosol samples collected during a pollution event were analyzed using ultrahigh-resolution FT-ICR MS. FLEXPART retroplume analysis shows the air masses were very aged (> 12 days). About 4000 molecular formulas were assigned to each of the mass spectra between m/z 100-1000. The majority of the assigned molecular formulas have unsaturated structures with CHO and CHNO elemental compositions. WSOC have an average O/C ratio of ~0.45, relatively low compared to O/C ratios of other aged aerosol which might be the result of evaporation and fragmentation during long-range transport. The increase in aerosol loading during 9/24 was linked to biomass burning emissions from North America by FLEXPART retroplumes and MODIS fire counts. This was confirmed with WSOC biomass burning markers and with the morphology and mixing state of particles as determined by scanning electron microscopy. The presence of markers characteristic of aqueous-phase reactions of biomass burning phenolic species suggests that the aerosol collected at Pico had undergone cloud processing. The air masses on 9/25 were more aged (~15 days) and influenced by marine emissions, as indicated by organosulfates and species characteristic for marine aerosol (e.g. fatty acids). The change in air masses for

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  20. 78 FR 12052 - Agency Information Collection Activities: Proposed Collection; Comment Request; Ambient Air...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-21

    ... AGENCY Agency Information Collection Activities: Proposed Collection; Comment Request; Ambient Air... is planning to submit a request to renew an existing approved Information Collection Request (ICR) to... proposed information collection as described below. DATES: Comments must be submitted on or before April...

  1. A new approach for retrieving the UV-vis optical properties of ambient aerosols

    NASA Astrophysics Data System (ADS)

    Bluvshtein, Nir; Flores, J. Michel; Segev, Lior; Rudich, Yinon

    2016-08-01

    Atmospheric aerosols play an important part in the Earth's energy budget by scattering and absorbing incoming solar and outgoing terrestrial radiation. To quantify the effective radiative forcing due to aerosol-radiation interactions, researchers must obtain a detailed understanding of the spectrally dependent intensive and extensive optical properties of different aerosol types. Our new approach retrieves the optical coefficients and the single-scattering albedo of the total aerosol population over 300 to 650 nm wavelength, using extinction measurements from a broadband cavity-enhanced spectrometer at 315 to 345 nm and 390 to 420 nm, extinction and absorption measurements at 404 nm from a photoacoustic cell coupled to a cavity ring-down spectrometer, and scattering measurements from a three-wavelength integrating nephelometer. By combining these measurements with aerosol size distribution data, we retrieved the time- and wavelength-dependent effective complex refractive index of the aerosols. Retrieval simulations and laboratory measurements of brown carbon proxies showed low absolute errors and good agreement with expected and reported values. Finally, we implemented this new broadband method to achieve continuous spectral- and time-dependent monitoring of ambient aerosol population, including, for the first time, extinction measurements using cavity-enhanced spectrometry in the 315 to 345 nm UV range, in which significant light absorption may occur.

  2. Ambient aerosols remain highly acidic despite dramatic sulfate reductions

    NASA Astrophysics Data System (ADS)

    Nenes, Athanasios; Weber, Rodney; Guo, Hongyu; Russell, Armistead

    2016-04-01

    The pH of fine particles has many vital environmental impacts. By affecting aerosol concentrations, chemical composition and toxicity, particle pH is linked to regional air quality and climate, and adverse effects on human health. Sulfate is often the main acid component that drives pH of fine particles (i.e., PM2.5) and is neutralized to varying degrees by gas phase ammonia. Sulfate levels have decreased by approximately 70% over the Southeastern United States in the last fifteen years, but measured ammonia levels have been fairly steady implying the aerosol may becoming more neutral. Using a chemically comprehensive data set, combined with a thermodynamic analysis, we show that PM2.5 in the Southeastern U.S. is highly acidic (pH between 0 and 2), and that pH has remained relatively unchanged throughout the past decade and a half of decreasing sulfate. Even with further sulfate reductions, pH buffering by gas-particle partitioning of ammonia is expected to continue until sulfate drops to near background levels, indicating that fine particle pH will remain near current levels into the future. These results are non-intuitive and reshape expectations of how sulfur emission reductions impact air quality in the Southeastern U.S. and possibly other regions across the globe.

  3. Investigating the Formation of Ambient Secondary Organic Aerosol in Southeastern USA

    NASA Astrophysics Data System (ADS)

    Weber, R.; Sullivan, A.; Peltier, R.; Hennigan, C.; Yan, B.; Zheng, M.; Kaynak, B.; Russell, J.; Brock, C.; de Gouw, J.; Warneke, C.; Holloway, J.; Atlas, E.; Edgerton, E.

    2006-12-01

    It is well known that during periods of intense photochemistry the formation of secondary organic aerosol (SOA) is a major source for fine particle mass, and a significant contributor to poor air quality. This process is thought to be especially important in the southeastern United States due to high concentrations of both anthropogenic and biogenic precursor organic compounds. SOA formation, however, is poorly understood. Recent studies by a number of investigators in widely different urban regions show that model simulations based on SOA yields from smog chamber experiments under predict the organic aerosol by factors of roughly 5 to 15. These studies also show organic aerosol can be formed rapidly within 5 to 20 hours following emission. We have found similar results based on data collected from a suite of instrumentation deployed on the NOAA WP-3B aircraft during the New England Air Quality Study of August 2004. Throughout the mission plumes transported from New York City were intercepted various distances downwind. For plumes less that roughly 20 hrs old concentrations of water-soluble organic compounds (WSOC) in fine particles rapidly increased relative to carbon monoxide with increasing plume age. WSOC concentrations were 8 +/- 2 times higher than expected based on calculations using current SOA yields, and although WSOC was highly correlated with anthropogenic tracers, no correlation was found to biogenic VOCs. Subsequent measurements with the same suite of instruments over metropolitan Atlanta and a large region of north Georgia resulted in similar findings despite measured biogenic VOC concentrations higher by factors of 10 to 100. WSOC was only correlated with anthropogenic emissions, chemically aged air masses had WSOC concentrations relative to CO similar to that found in the northeast, and WSOC concentrations were roughly 5 +/- 1 times higher than that predicted by the Community Multi-scale Air Quality Model (CMAQ). In contrast, radiocarbon analysis

  4. 76 FR 60020 - Agency Information Collection Activities: Proposed Collection; Comment Request; Ambient Air...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-28

    .../quality control data and air monitoring network design information. The U.S. EPA and others (e.g., state... AGENCY Agency Information Collection Activities: Proposed Collection; Comment Request; Ambient Air... is planning to submit a request to renew an existing approved Information Collection Request (ICR)...

  5. Characterization of ambient aerosols at the San Francisco International Airport using BioAerosol Mass Spectrometry

    SciTech Connect

    Steele, P T; McJimpsey, E L; Coffee, K R; Fergenson, D P; Riot, V J; Tobias, H J; Woods, B W; Gard, E E; Frank, M

    2006-03-16

    The BioAerosol Mass Spectrometry (BAMS) system is a rapidly fieldable, fully autonomous instrument that can perform correlated measurements of multiple orthogonal properties of individual aerosol particles. The BAMS front end uses optical techniques to nondestructively measure a particle's aerodynamic diameter and fluorescence properties. Fluorescence can be excited at 266nm or 355nm and is detected in two broad wavelength bands. Individual particles with appropriate size and fluorescence properties can then be analyzed more thoroughly in a dual-polarity time-of-flight mass spectrometer. Over the course of two deployments to the San Francisco International Airport, more than 6.5 million individual aerosol particles were fully analyzed by the system. Analysis of the resulting data has provided a number of important insights relevant to rapid bioaerosol detection, which are described here.

  6. Source apportionment of ambient aerosol applying PMF on AMS mobile and stationary data

    NASA Astrophysics Data System (ADS)

    Mohr, C.; Weimer, S.; Richter, R.; Decarlo, P. F.; Chirico, R.; Heringa, M. F.; Prévôt, A. S. H.; Baltensperger, U.

    2009-04-01

    Ambient aerosols are divided into the categories "primary" and "secondary", referring to particles directly emitted into the air, or formed out of precursor species such as volatile organic compounds, respectively. Main sources for primary urban aerosol and precursor species are traffic emissions, but also wood burning for domestic heating purposes especially in winter time (Alfarra et al., 2007). The quantification of various types of aerosol components is important for source identification which in turn is the basis of all mitigation activities. Positive Matrix Factorization (PMF) is a statistical based source apportionment tool that uses constrained, weighted least squares estimation to determine source profiles and strengths. PMF has been applied recently for the first time on highly time resolved organic mass spectra (Lanz et al., 2007) measured by an Aerodyne aerosol mass spectrometer (AMS) (Canagaratna et al., 2007). For the data presented here, two AMS were deployed together with additional instrumentation in the metropolitan area of Zurich in winter 2007/2008. The high-resolution time-of-flight AMS was stationed at an urban background site in the center, 30 meters from and shielded against direct traffic emissions. The quadrupole-based AMS was deployed in a mobile van allowing for on-road submicron aerosol composition measurements, and investigations into the spatial variability of aerosol concentration and composition. Results indicate that traffic emissions are the main contributor to submicron aerosol concentrations measured on-road. Hydrocarbon-like organic aerosol (HOA), a marker for traffic emissions (Lanz et al. 2007), dominates the primary aerosol mass, together with black carbon (BC). BC was monitored with the MAAP (multi angle absorption photometer). Another significant contributor to primary organic aerosol mass in downtown Zurich is domestic wood burning for heating purposes. Traffic and wood burning emissions make up roughly 50% of the total

  7. Estimating the toxicity of ambient fine aerosols using freshwater rotifer Brachionus calyciflorus (Rotifera: Monogononta).

    PubMed

    Verma, Vishal; Rico-Martinez, Roberto; Kotra, Neel; Rennolds, Corey; Liu, Jiumeng; Snell, Terry W; Weber, Rodney J

    2013-11-01

    The toxicity of atmospheric fine particulate matter (PM2.5) in Atlanta is assessed using freshwater rotifers (Brachionus calyciflorus). The PM-laden quartz filters were extracted in both water and methanol. Aerosol extracts were passed through a C-18 column to separate the PM components into hydrophobic and hydrophilic fractions. Toxicity data reported in the units of LC50 (concentration that kills 50% of the test population in 24 h) shows that ambient particles are toxic to the rotifers with LC50 values ranging from 5 to 400 μg of PM. The methanol extract of the aerosols was substantially more toxic (8 ± 6 times) to the rotifers compared to the water extracts. A sizeable fraction (>70%) of toxicity was found to be associated with the hydrophobic fraction of PM. However, none of the bulk aerosol species was strongly correlated with the LC50 values suggesting a complicated mechanism of toxicity probably involving synergistic interactions of various PM components.

  8. Ambient Aerosol in Southeast Asia: High Resolution Aerosol Mass Spectrometer Measurements Over Oil Palm (Elaeis guineensis)

    NASA Astrophysics Data System (ADS)

    Phillips, G.; Dimarco, C.; Misztal, P.; Nemitz, E.; Farmer, D.; Kimmel, J.; Jimenez, J.

    2008-12-01

    The emission of organic compounds in the troposphere is important factor in the formation of secondary organic aerosol (SOA). A very large proportion of organic material emitted globally is estimated to arise from biogenic sources, with almost half coming from tropical and sub-tropical forests. Preliminary analyses of leave cuvette emission studies suggest that oil palm (Elaeis guineensis) is a significantly larger source of isoprene than tropical forest. Much larger sources of isoprene over oil palm allied with a larger anthropogenic component of local emissions contrast greatly with the remote tropical forest environment and therefore the character of SOA formed may differ significantly. These issues, allied with the high price of palm oil on international markets leading to increased use of land for oil palm production, could give rise to rapidly changing chemical and aerosol regimes in the tropics. It is therefore important to understand the current emissions and composition of organic aerosol over all important land-uses in the tropical environment. This in turn will lead to a greater understanding of the present, and to an improvement in predictive capacity for the future system. To help address these issues, a high resolution time of flight aerosol mass spectrometer (HR-ToF-AMS) was deployed in the Sabahmas (PPB OIL) oil palm plantation near Lahad Datu, in Eastern Sabah, as part of the field component of the Aerosol Coupling in the Earth System (ACES) project, part of the UK NERC APPRAISE program. This project was allied closely with measurements made of similar chemical species and aerosol components at a forest site in the Danum Valley as part of the UK Oxidant and Particle Photochemical Processes above a Southeast Asian tropical rainforest (OP3) project. Measurements of submicron non- refractory aerosol composition are presented along with some preliminary analysis of chemically resolved aerosol fluxes made with a new eddy covariance system, based on the

  9. Seasonal variations of biogenic secondary organic aerosol tracers in ambient aerosols from Alaska

    NASA Astrophysics Data System (ADS)

    Haque, Md. Mozammel; Kawamura, Kimitaka; Kim, Yongwon

    2016-04-01

    We investigated total suspended particles (TSP) collected from central Alaska, USA for molecular compositions of secondary organic aerosol (SOA) derived from the oxidation of biogenic volatile organic compounds (BVOCs). Isoprene-, α-/β-pinene- and β-caryophyllene-SOA tracers were determined using gas chromatography-mass spectrometry. The concentration ranges of isoprene, α-/β-pinene and β-caryophyllene oxidation products were 0.02-18.6 ng m-3 (ave. 4.14 ng m-3), 0.42-8.24 ng m-3 (2.01 ng m-3) and 0.10-9 ng m-3 (1.53 ng m-3), respectively. Isoprene-SOA tracers showed higher concentrations in summer (ave. 8.77 ng m-3), whereas α-/β-pinene- and β-caryophyllene-SOA tracers exhibited highest levels in spring (3.55 ng m-3) and winter (4.04 ng m-3), respectively. β-Caryophyllinic acid and levoglucosan showed a positive correlation, indicating that biomass burning may be a major source for β-caryophyllene. We found that mean contributions of isoprene oxidation products to organic carbon (OC) and water-soluble organic (WSOC) (0.56% and 1.2%, respectively) were higher than those of α-/β-pinene (0.31% and 0.55%) and β-caryophyllene (0.08% and 0.13%). Using a tracer-based method, we estimated the concentrations of secondary organic carbon (SOC) produced from isoprene, α-/β-pinene and β-caryophyllene to be 0.66-718 ngC m-3 (ave. 159 ngC m-3), 7.4-143 ngC m-3 (35 ngC m-3) and 4.5-391 ngC m-3 (66.3 ngC m-3), respectively. Based on SOA tracers, this study suggests that isoprene is a more important precursor for the production of biogenic SOA than α-/β-pinene and β-caryophyllene in subarctic Alaska.

  10. Portable Aerosol Contaminant Extractor

    DOEpatents

    Carlson, Duane C.; DeGange, John J.; Cable-Dunlap, Paula

    2005-11-15

    A compact, portable, aerosol contaminant extractor having ionization and collection sections through which ambient air may be drawn at a nominal rate so that aerosol particles ionized in the ionization section may be collected on charged plate in the collection section, the charged plate being readily removed for analyses of the particles collected thereon.

  11. Online Measurements of Water-Soluble Iron in Ambient Aerosols: A new Technique

    NASA Astrophysics Data System (ADS)

    Rastogi, N.; Oakes, M.; Weber, R. J.; Majestic, B. J.; Shafer, M. M.; Snyder, D. C.; Schauer, J. J.

    2008-05-01

    Water-soluble iron, i.e. Fe(II) (hereafter, WS-Fe), is a redox active metal that can act as a catalyst in the production of reactive oxygen species (ROS). In atmospheric aerosol particles, WS-Fe may significantly impact human health and the atmospheric oxidative capacity. Further, WS-Fe acts as a critical nutrient for marine organisms and has been hypothesized to limit phytoplankton productivity in high nitrate, low-chlorophyll ocean regions. In order to assess the role of aerosol WS-Fe on human health, atmospheric chemistry and ocean biogeochemistry, it is necessary to understand its major sources, transport, transformation processes and sinks. Filter-based measurements with several (6-24) hours integration time are predominately used to quantify WS-Fe in aerosols but provide limited insight into acute exposures that could be higher than daily averages, or sources having high temporal variability. Generally, mineral dust and its processing with acidic pollutants, is considered the dominant source of WS-Fe, however, recent studies have reported combustion emissions are also a possible source. A time-resolved data set may help in identifying WS-Fe sources, atmospheric transformations and possible sinks. We have developed a new system for online quantitative analyses of WS-Fe present in ambient aerosols with a 12-minute integration time. It mainly consists of Particle-Into-Liquid Sampler (PILS), a liquid waveguide capillary cell (LWCC) and a portable UV-Visible spectrophotometer. The complete system is automated so that first the liquid sample (water-extract of ambient aerosols from PILS) is mixed with ferrozine (complexing reagent) by pumping them simultaneously (10:1) through a serpentine reactor and a 100 turn mixing coil using a peristaltic pump. After holding the mixed solution in the mixing coil for three minutes, the sample is pumped through the LWCC and held there for two minutes to acquire the absorbance of the solution at 562 nm (for Fe

  12. Instrument Would Detect and Collect Biological Aerosols

    NASA Technical Reports Server (NTRS)

    Savoy, Steve; Mayo, Mike

    2006-01-01

    A proposed compact, portable instrument would sample micron-sized airborne particles, would discriminate between biological ones (e.g., bacteria) and nonbiological ones (e.g., dust particles), and would collect the detected biological particles for further analysis. The instrument is intended to satisfy a growing need for means of rapid, inexpensive collection of bioaerosols in a variety of indoor and outdoor settings. Purposes that could be served by such collection include detecting airborne pathogens inside buildings and their ventilation systems, measuring concentrations of airborne biological contaminants around municipal waste-processing facilities, monitoring airborne effluents from suspected biowarfare facilities, and warning of the presence of airborne biowarfare agents

  13. Phase state of ambient aerosol linked with water uptake and chemical aging in the southeastern US

    NASA Astrophysics Data System (ADS)

    Pajunoja, Aki; Hu, Weiwei; Leong, Yu J.; Taylor, Nathan F.; Miettinen, Pasi; Palm, Brett B.; Mikkonen, Santtu; Collins, Don R.; Jimenez, Jose L.; Virtanen, Annele

    2016-09-01

    During the summer 2013 Southern Aerosol and Oxidant Study (SOAS) field campaign in a rural site in the southeastern United States, the effect of hygroscopicity and composition on the phase state of atmospheric aerosol particles dominated by the organic fraction was studied. The analysis is based on hygroscopicity measurements by a Hygroscopic Tandem Differential Mobility Analyzer (HTDMA), physical phase state investigations by an Aerosol Bounce Instrument (ABI) and composition measurements using a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). To study the effect of atmospheric aging on these properties, an OH-radical oxidation flow reactor (OFR) was used to simulate longer atmospheric aging times of up to 3 weeks. Hygroscopicity and bounce behavior of the particles had a clear relationship showing higher bounce at elevated relative humidity (RH) values for less hygroscopic particles, which agrees well with earlier laboratory studies. Additional OH oxidation of the aerosol particles in the OFR increased the O : C and the hygroscopicity resulting in liquefying of the particles at lower RH values. At the highest OH exposures, the inorganic fraction starts to dominate the bounce process due to production of inorganics and concurrent loss of organics in the OFR. Our results indicate that at typical ambient RH and temperature, organic-dominated particles stay mostly liquid in the atmospheric conditions in the southeastern US, but they often turn semisolid when dried below ˜ 50 % RH in the sampling inlets. While the liquid phase state suggests solution behavior and equilibrium partitioning for the SOA particles in ambient air, the possible phase change in the drying process highlights the importance of thoroughly considered sampling techniques of SOA particles.

  14. SUBHOURLY AMBIENT AEROSOL COLLECTION AND ELEMENTAL ANALYSIS. (R825269)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  15. Temporal variability in Chemical and Stable isotopic characteristics of ambient bulk aerosols over a coastal environment of India

    NASA Astrophysics Data System (ADS)

    Agnihotri, R.; Karapurkar, S. G.; Sarma, V. V.; Praveen, P.; Kumar, M. D.

    2012-12-01

    Atmospheric carbonaceous aerosols are known to influence regional biogeochemical cycles of carbon (C) and nitrogen (N) in addition to regional radiation budgets. Owing to multiplicity of primary sources of natural and anthropogenic origin, their detailed chemical and isotopic characterization can greatly help in source apportionment and identifying secondary processes. From the roof of NIO-Goa (India) [15.46οN, 73.8oE; at ~55.8 MASL], atmospheric bulk aerosols (n=22) were collected on Quartz filters, from 2009 December to January 2011 covering entire 2010 (except monsoon period) to investigate temporal variability in their chemical and isotopic characteristics of the carbonaceous fraction i.e. TC, TOC and TN mass concentrations and their stable isotopic ratios (δ13CTC, δ13CTOC and δ15NTN). Both δ13CTC and δ13CTOC varied in narrow ranges (-24.9±1.1‰, -25.7±0.9‰ respectively), but significant differences were observed between the two during pre-monsoon months (as high as 2.3‰), possibly due to mixing of inorganic mineral dust. δ15NTN values showed a wide range of variability (average = 13.6±7.2‰), with significantly lower values (~2-5‰; as reported earlier by Agnihotri et al. 2011) during pre-monsoon period compared to those during winter (as high as ~26‰). Using δ13CTC values and two end-member mixing model (assuming δ13C of marine and continental carbon as -21 and -27‰ respectively), the average marine carbon fraction for Goa aerosols was estimated as 36±18.5%, significantly higher than reported for Chennai aerosols (~19%) (Pavuluri et al., 2011), but close to the reported average for marine aerosols at Bermuda (38%) (Turekian et al., 2003). Chemical and isotopic characteristics of ambient aerosols over Goa along with contemporaneous meteorological data indicate that winter aerosols contain significant proportion of carbonaceous fraction originated from biomass burning and other anthropogenic activities carried out in northern parts of

  16. Acute lung function responses to ambient acid aerosol exposures in children

    SciTech Connect

    Raizenne, M.E.; Burnett, R.T.; Stern, B.; Franklin, C.A.; Spengler, J.D.

    1989-02-01

    We examined the relationship between lung function changes and ambient acid aerosol episodes in children attending a residential summer camp. Young females (112) performed daily spirometry, and 96 were assessed on one occasion for airway hyperresponsiveness using a methacholine bronchoprovocation test. Air quality measurements were performed on site and four distinct acid aerosol episodes were observed during the 41-day study. The maximum values observed during the 41-day study were: O/sub 3/ at 143 ppb; H/sub 2/SO/sub 4/ at 47.7 micrograms/m/sup 3/; and (H+) at 550 nmole/m/sup 3/. Maximum decrements of 3.5 and 7% for FEV1 and PEF, respectively, were observed to be associated with the air pollution episodes. There was some evidence of a differential lung function response to the episodes where children with a positive response to a methacholine challenge had larger decrements compared to their nonresponsive counterparts.

  17. Acute lung function responses to ambient acid aerosol exposures in children.

    PubMed

    Raizenne, M E; Burnett, R T; Stern, B; Franklin, C A; Spengler, J D

    1989-02-01

    We examined the relationship between lung function changes and ambient acid aerosol episodes in children attending a residential summer camp. Young females (112) performed daily spirometry, and 96 were assessed on one occasion for airway hyperresponsiveness using a methacholine bronchoprovocation test. Air quality measurements were performed on site and four distinct acid aerosol episodes were observed during the 41-day study. The maximum values observed during the 41-day study were: O3 at 143 ppb; H2SO4 at 47.7 micrograms/m3; and [H+] at 550 nmole/m3. Maximum decrements of 3.5 and 7% for FEV1 and PEF, respectively, were observed to be associated with the air pollution episodes. There was some evidence of a differential lung function response to the episodes where children with a positive response to a methacholine challenge had larger decrements compared to their nonresponsive counterparts.

  18. Photoacoustic optical properties at UV, VIS, and near IR wavelengths for laboratory generated and winter time ambient urban aerosols

    SciTech Connect

    Gyawali, Madhu S.; Arnott, W. Patrick; Zaveri, Rahul A.; Song, Chen; Moosmuller, H.; Liu, Li; Mishchenko, M.; Chen, L-W A.; Green, M.; Watson, J. G.; Chow, J. C.

    2012-03-08

    We present the laboratory and ambient photoacoustic (PA) measurement of aerosol light absorption coefficients at ultraviolet wavelength (i.e., 355 nm) and compare with measurements at 405, 532, 870, and 1047 nm. Simultaneous measurements of aerosol light scattering coefficients were achieved by the integrating reciprocal nephelometer within the PA's acoustic resonator. Absorption and scattering measurements were carried out for various laboratory generated aerosols, including salt, incense, and kerosene soot to evaluate the instrument calibration and gain insight on the spectral dependence of aerosol light absorption and scattering. Ambient measurements were obtained in Reno, Nevada, between 18 December 2009 and 18 January 2010. The measurement period included days with and without strong ground level temperature inversions, corresponding to highly polluted (freshly emitted aerosols) and relatively clean (aged aerosols) conditions. Particulate matter (PM) concentrations were measured and analyzed with other tracers of traffic emissions. The temperature inversion episodes caused very high concentration of PM{sub 2.5} and PM{sub 10} (particulate matter with aerodynamic diameters less than 2.5 {mu}m and 10 {mu}m, respectively) and gaseous pollutants: carbon monoxide (CO), nitric oxide (NO), and nitrogen dioxide (NO{sub 2}). The diurnal change of absorption and scattering coefficients during the polluted (inversion) days increased approximately by a factor of two for all wavelengths compared to the clean days. The spectral variation in aerosol absorption coefficients indicated a significant amount of absorbing aerosol from traffic emissions and residential wood burning. The analysis of single scattering albedo (SSA), Angstrom exponent of absorption (AEA), and Angstrom exponent of scattering (AES) for clean and polluted days provides evidences that the aerosol aging and coating process is suppressed by strong temperature inversion under cloudy conditions. In general

  19. Photoacoustic Optical Properties at UV, VIS, and near IR Wavelengths for Laboratory Generated and Winter Time Ambient Urban Aerosols

    NASA Technical Reports Server (NTRS)

    Gyawali, M.; Arnott, W. P.; Zaveri, R. A.; Song, C.; Moosmuller, H.; Liu, L.; Mishchenko, M. I.; Chen, L.-W.A.; Green, M. C.; Watson, J. G.; Chow, J. C.

    2012-01-01

    We present the laboratory and ambient photoacoustic (PA) measurement of aerosol light absorption coefficients at ultraviolet wavelength (i.e., 355 nm) and compare with measurements at 405, 532, 870, and 1047 nm. Simultaneous measurements of aerosol light scattering coefficients were achieved by the integrating reciprocal nephelometer within the PA's acoustic resonator. Absorption and scattering measurements were carried out for various laboratory generated aerosols, including salt, incense, and kerosene soot to evaluate the instrument calibration and gain insight on the spectral dependence of aerosol light absorption and scattering. Ambient measurements were obtained in Reno, Nevada, between 18 December 2009 and 18 January 2010. The measurement period included days with and without strong ground level temperature inversions, corresponding to highly polluted (freshly emitted aerosols) and relatively clean (aged aerosols) conditions. Particulate matter (PM) concentrations were measured and analyzed with other tracers of traffic emissions. The temperature inversion episodes caused very high concentration of PM (sub 2.5) and PM( sub 10) (particulate matter with aerodynamic diameters less than 2.5 micrometers and 10 micrometers, respectively) and gaseous pollutants: carbon monoxide (CO), nitric oxide (NO), and nitrogen dioxide (NO2). The diurnal change of absorption and scattering coefficients during the polluted (inversion) days increased approximately by a factor of two for all wavelengths compared to the clean days. The spectral variation in aerosol absorption coefficients indicated a significant amount of absorbing aerosol from traffic emissions and residential wood burning. The analysis of single scattering albedo (SSA), Angstrom exponent of absorption (AEA), and Angstrom exponent of scattering (AES) for clean and polluted days provides evidences that the aerosol aging and coating process is suppressed by strong temperature inversion under cloudy conditions. In

  20. Individual aerosol particles in ambient and updraft conditions below convective cloud bases in the Oman mountain region

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    An airborne study of cloud microphysics provided an opportunity to collect aerosol particles in ambient and updraft conditions of natural convection systems for transmission electron microscopy (TEM). Particles were collected simultaneously on lacey carbon and calcium-coated carbon (Ca-C) TEM grids, providing information on particle morphology and chemistry and a unique record of the particle's physical state on impact. In total, 22 particle categories were identified, including single, coated, aggregate, and droplet types. The fine fraction comprised up to 90% mixed cation sulfate (MCS) droplets, while the coarse fraction comprised up to 80% mineral-containing aggregates. Insoluble (dry), partially soluble (wet), and fully soluble particles (droplets) were recorded on Ca-C grids. Dry particles were typically silicate grains; wet particles were mineral aggregates with chloride, nitrate, or sulfate components; and droplets were mainly aqueous NaCl and MCS. Higher numbers of droplets were present in updrafts (80% relative humidity (RH)) compared with ambient conditions (60% RH), and almost all particles activated at cloud base (100% RH). Greatest changes in size and shape were observed in NaCl-containing aggregates (>0.3 µm diameter) along updraft trajectories. Their abundance was associated with high numbers of cloud condensation nuclei (CCN) and cloud droplets, as well as large droplet sizes in updrafts. Thus, compositional dependence was observed in activation behavior recorded for coarse and fine fractions. Soluble salts from local pollution and natural sources clearly affected aerosol-cloud interactions, enhancing the spectrum of particles forming CCN and by forming giant CCN from aggregates, thus, making cloud seeding with hygroscopic flares ineffective in this region.

  1. Characterization of primary organic aerosol emissions from meat cooking, trash burning, and motor vehicles with high-resolution aerosol mass spectrometry and comparison with ambient and chamber observations.

    PubMed

    Mohr, Claudia; Huffman, Alex; Cubison, Michael J; Aiken, Allison C; Docherty, Kenneth S; Kimmel, Joel R; Ulbrich, Ingrid M; Hannigan, Michael; Jimenez, Jose L

    2009-04-01

    Organic aerosol (OA) emissions from motor vehicles, meat-cooking and trash burning are analyzed here using a high-resolution aerosol mass spectrometer (AMS). High resolution data show that aerosols emitted by combustion engines and plastic burning are dominated by hydrocarbon-like organic compounds. Meat cooking and especially paper burning emissions contain significant fractions of oxygenated organic compounds; however, their unit-resolution mass spectral signatures are very similar to those from ambient hydrocarbon-like OA, and very different from the mass spectra of ambient secondary or oxygenated OA (OOA). Thus, primary OA from these sources is unlikelyto be a significant direct source of ambient OOA. There are significant differences in high-resolution tracer m/zs that may be useful for differentiating some of these sources. Unlike in most ambient spectra, all of these sources have low total m/z 44 and this signal is not dominated by the CO2+ ion. All sources have high m/z 57, which is low during high OOA ambient periods. Spectra from paper burning are similar to some types of biomass burning OA, with elevated m/z 60. Meat cooking aerosols also have slightly elevated m/z 60, whereas motor vehicle emissions have very low signal at this m/z.

  2. Secondary Organic Aerosol Formation from the Photooxidation of Complex Hydrocarbon Mixtures: Composition, effect of SO2, and Relevance to Ambient Aerosol

    NASA Astrophysics Data System (ADS)

    Surratt, J. D.; Gao, S.; Knipping, E.; Edgerton, E.; Shahgoli, M.; Seinfeld, J. H.; Edney, E.; Kleindiesnt, T.; Lewandowski, M.; Offenberg, J.; Jaoui, M.

    2005-12-01

    Secondary organic aerosol (SOA) formation from single hydrocarbon precursors is commonly studied in smog chamber experiments to obtain SOA yield and organic composition data. However, very few complex air mixture experiments have been conducted to simulate possible conditions in ambient atmospheres. A six-phase experiment involving various combinations of alpha-pinene, toluene, isoprene, and SO2 were irradiated in the EPA's dynamic smog chamber at the National Exposure Research Laboratory in Raleigh, NC. Glass fiber filters and impactor plates were collected for each phase of the experiment to identify and quantify the nature of the SOA composition. The following suite of analytical techniques analyzed the resultant polar organic compounds and the high molecular weight species: liquid chromatography-electrospray ionization (ESI)-mass spectrometry, gas chromatography-mass spectrometry, ESI-ion trap mass spectrometry, matrix assisted laser desorption (MALDI)-time of flight mass spectrometry, and high-resolution mass spectrometry. When SO2 is present in the chamber, increases in the gravimetric aerosol mass concentration and in the abundance of polar organic compounds are observed, likely suggesting an acid catalysis effect stemming from the conversion of SO2 to H2SO4 that condenses onto aerosol formed. The addition of isoprene to a alpha-pinene/toluene mixture is found to lower the amount of aerosol produced and is also found to lower the abundance of organic compounds identified by the various analytical techniques. Lastly, many of the polar organic compounds identified and quantified here are also seen in the Southeastern Aerosol Research and Characterization (SEARCH) network during the summer of 2004. In particular, a sulfur and nitrogen containing organic species (MW = 295 gmol) is found to be the most abundant polar organic species identified in this field study (~28 % on average of the total identified organic mass). This species is also detected in the chamber

  3. Predicting ambient aerosol thermal-optical reflectance (TOR) measurements from infrared spectra: organic carbon

    NASA Astrophysics Data System (ADS)

    Dillner, A. M.; Takahama, S.

    2015-03-01

    Organic carbon (OC) can constitute 50% or more of the mass of atmospheric particulate matter. Typically, organic carbon is measured from a quartz fiber filter that has been exposed to a volume of ambient air and analyzed using thermal methods such as thermal-optical reflectance (TOR). Here, methods are presented that show the feasibility of using Fourier transform infrared (FT-IR) absorbance spectra from polytetrafluoroethylene (PTFE or Teflon) filters to accurately predict TOR OC. This work marks an initial step in proposing a method that can reduce the operating costs of large air quality monitoring networks with an inexpensive, non-destructive analysis technique using routinely collected PTFE filter samples which, in addition to OC concentrations, can concurrently provide information regarding the composition of organic aerosol. This feasibility study suggests that the minimum detection limit and errors (or uncertainty) of FT-IR predictions are on par with TOR OC such that evaluation of long-term trends and epidemiological studies would not be significantly impacted. To develop and test the method, FT-IR absorbance spectra are obtained from 794 samples from seven Interagency Monitoring of PROtected Visual Environment (IMPROVE) sites collected during 2011. Partial least-squares regression is used to calibrate sample FT-IR absorbance spectra to TOR OC. The FTIR spectra are divided into calibration and test sets by sampling site and date. The calibration produces precise and accurate TOR OC predictions of the test set samples by FT-IR as indicated by high coefficient of variation (R2; 0.96), low bias (0.02 μg m-3, the nominal IMPROVE sample volume is 32.8 m3), low error (0.08 μg m-3) and low normalized error (11%). These performance metrics can be achieved with various degrees of spectral pretreatment (e.g., including or excluding substrate contributions to the absorbances) and are comparable in precision to collocated TOR measurements. FT-IR spectra are also

  4. Automated Measurements of Ambient Aerosol Chemical Composition and its Dry and Wet Size Distributions at Pittsburgh Supersite

    NASA Astrophysics Data System (ADS)

    Khlystov, A. Y.; Stanier, C.; Chun, W.; Vayenas, D.; Mandiro, M.; Pandis, S. N.

    2001-12-01

    Ambient aerosol particles change size with changes in ambient relative humidity. The magnitude of the size change depends on the hygroscopic properties of the particles, which is determined by their chemical composition. Hygroscopic properties of particles influence many environmentally important aerosol qualities, such as light scattering and partitioning between the gas and particle phases of semivolitile compounds. Studying the hygroscopic growth of ambient particles is thus of paramount importance. The highroscopic growth of ambient particles and their chemical composition are measured continuously within the Pittsburgh Air Quality Study (EPA supersite program). The hygroscopic size changes are measured using an automated system built for this study. The system consists of two Scanning Mobility Particle Sizers (SMPS, TSI Inc.) and an Aerodynamic Particle Sizer (APS, TSI Inc.). The three instruments measure aerosol size distribution between 5 nanometers and 10 micrometers in diameter. The inlets of the instruments and the sheath air lines of the SMPS systems are equipped with computer controlled valves that direct air through Nafion dryers (PermaPure Inc.) or bypass them. The Nafion dryers are drying the air stream below 40% RH at which point ambient particles are expected to lose most or all water and thus be virtually dry. To avoid changes in relative humidity and evaporation of volatile particles due to temperature differences the system is kept at ambient temperature. The system measures alternatively dry (below 40% RH) and wet (actual ambient RH) aerosol size distributions every 6 minutes. The hygroscopic growth observed with the size-spectrometer system is compared with theoretic predictions based on the chemical composition of aerosol particles. A modified semi-continuous Steam-Jet Aerosol Collector provides the total available budget (particles and gas) of water-soluble species, which is used as an input to the thermodynamic model. The model calculates

  5. The Collection 6 MODIS aerosol products over land and ocean

    NASA Astrophysics Data System (ADS)

    Levy, R. C.; Mattoo, S.; Munchak, L. A.; Remer, L. A.; Sayer, A. M.; Patadia, F.; Hsu, N. C.

    2013-11-01

    The twin Moderate resolution Imaging Spectroradiometer (MODIS) sensors have been flying on Terra since 2000 and Aqua since 2002, creating an extensive data set of global Earth observations. Here, we introduce the Collection 6 (C6) algorithm to retrieve aerosol optical depth (AOD) and aerosol size parameters from MODIS-observed spectral reflectance. While not a major overhaul from the previous Collection 5 (C5) version, there are enough changes that there are significant impacts to the products and their interpretation. The C6 aerosol data set will be created from three separate retrieval algorithms that operate over different surface types. These are the two "Dark Target" (DT) algorithms for retrieving (1) over ocean (dark in visible and longer wavelengths) and (2) over vegetated/dark-soiled land (dark in the visible), plus the "Deep Blue" (DB) algorithm developed originally for retrieving (3) over desert/arid land (bright in the visible). Here, we focus on DT-ocean and DT-land (#1 and #2). We have updated assumptions for central wavelengths, Rayleigh optical depths and gas (H2O, O3, CO2, etc.) absorption corrections, while relaxing the solar zenith angle limit (up to ≤ 84°) to increase poleward coverage. For DT-land, we have updated the cloud mask to allow heavy smoke retrievals, fine-tuned the assignments for aerosol type as function of season/location, corrected bugs in the Quality Assurance (QA) logic, and added diagnostic parameters such topographic altitude. For DT-ocean, improvements include a revised cloud mask for thin-cirrus detection, inclusion of wind speed dependence on the surface reflectance, updates to logic of QA Confidence flag (QAC) assignment, and additions of important diagnostic information. At the same time, we quantified how "upstream" changes to instrument calibration, land/sea masking and cloud masking will also impact the statistics of global AOD, and affect Terra and Aqua differently. For Aqua, all changes will result in reduced

  6. Phenols and hydroxy-PAHs (arylphenols) as tracers for coal smoke particulate matter: source tests and ambient aerosol assessments

    SciTech Connect

    Bernd R.T. Simoneit; Xinhui Bi; Daniel R. Oros; Patricia M. Medeiros; Guoying Sheng; Jiamo Fu

    2007-11-01

    Source tests were conducted to analyze and characterize diagnostic key tracers for emissions from burning of coals with various ranks. Coal samples included lignite from Germany, semibituminous coal from Arizona, USA, bituminous coal from Wales, UK and sample from briquettes of semibituminous coal, bituminous coal and anthracite from China. Ambient aerosol particulate matter was also collected in three areas of China and a background area in Corvallis, OR (U.S.) to confirm the presence of tracers specific for coal smoke. The results showed a series of aliphatic and aromatic hydrocarbons and phenolic compounds, including PAHs and hydroxy-PAHs as the major tracers, as well as a significant unresolved complex mixture (UCM) of compounds. The tracers that were found characteristic of coal combustion processes included hydroxy-PAHs and PAHs. Atmospheric ambient samples from Beijing and Taiyuan, cities where coal is burned in northern China, revealed that the hydroxy-PAH tracers were present during the wintertime, but not in cities where coal is not commonly used (e.g., Guangzhou, South China). Thus, the mass of hydroxy-PAHs can be apportioned to coal smoke and the source strength modeled by summing the proportional contents of EC (elemental carbon), PAHs, UCM and alkanes with the hydroxy-PAHs. 36 refs., 2 figs., 3 tabs.

  7. The Collection 6 MODIS aerosol products over land and ocean

    NASA Astrophysics Data System (ADS)

    Levy, R. C.; Mattoo, S.; Munchak, L. A.; Remer, L. A.; Sayer, A. M.; Hsu, N. C.

    2013-01-01

    The twin Moderate Imaging resolution Spectroradiometer (MODIS) sensors have been flying on Terra since 2000 and Aqua since 2002, creating an incredible dataset of global Earth observations. Here, we introduce the Collection 6 (C6) algorithm to retrieve aerosol optical depth (AOD) and aerosol size parameters from MODIS-observed spectral reflectance. While not a major overhaul from the previous Collection 5 (C5) version, there are enough changes that there is significant impact on the products and their interpretation. The C6 algorithm is comprised of three sub-algorithms for retrieving aerosol properties (1) over ocean (dark in visible and near-IR wavelengths), (2) over vegetated/dark-soiled land (dark in the visible) and (3) over desert/arid land (bright in the visible). Here, we focus on the changes to both "dark target" algorithms (#1 and #2; DT-ocean and DT-land). Affecting both DT algorithms, we have updated assumptions for central wavelengths, Rayleigh optical depths and gas (H2O, O3, CO2, etc.) absorption corrections, and relaxed the solar zenith angle limit (up to ≤ 84°) to increase pole-ward coverage. For DT-land, we have updated the cloud mask to allow heavy smoke retrievals, fine-tuned the assignments for aerosol type as function of season/location, corrected bugs in the Quality Assurance (QA) logic, and added diagnostic parameters such topographic altitude. For DT-ocean, improvements include a revised cloud mask for thin-cirrus detection, inclusion of wind speed dependence in the retrieval, updates to logic of QA Confidence flag (QAC) assignment, and additions of important diagnostic information. All together, the changes to the DT algorithms result in reduced global AOD (by 0.02) over ocean and increased AOD (by 0.01) over land, along with some changes in spatial coverage. Preliminary validation shows that compared to surface-based sunphotometer data, the C6 DT-products should compare at least as well as those from C5. However, at the same time as we

  8. An automated baseline correction protocol for infrared spectra of atmospheric aerosols collected on polytetrafluoroethylene (Teflon) filters

    NASA Astrophysics Data System (ADS)

    Kuzmiakova, Adele; Dillner, Ann M.; Takahama, Satoshi

    2016-06-01

    A growing body of research on statistical applications for characterization of atmospheric aerosol Fourier transform infrared (FT-IR) samples collected on polytetrafluoroethylene (PTFE) filters (e.g., Russell et al., 2011; Ruthenburg et al., 2014) and a rising interest in analyzing FT-IR samples collected by air quality monitoring networks call for an automated PTFE baseline correction solution. The existing polynomial technique (Takahama et al., 2013) is not scalable to a project with a large number of aerosol samples because it contains many parameters and requires expert intervention. Therefore, the question of how to develop an automated method for baseline correcting hundreds to thousands of ambient aerosol spectra given the variability in both environmental mixture composition and PTFE baselines remains. This study approaches the question by detailing the statistical protocol, which allows for the precise definition of analyte and background subregions, applies nonparametric smoothing splines to reproduce sample-specific PTFE variations, and integrates performance metrics from atmospheric aerosol and blank samples alike in the smoothing parameter selection. Referencing 794 atmospheric aerosol samples from seven Interagency Monitoring of PROtected Visual Environment (IMPROVE) sites collected during 2011, we start by identifying key FT-IR signal characteristics, such as non-negative absorbance or analyte segment transformation, to capture sample-specific transitions between background and analyte. While referring to qualitative properties of PTFE background, the goal of smoothing splines interpolation is to learn the baseline structure in the background region to predict the baseline structure in the analyte region. We then validate the model by comparing smoothing splines baseline-corrected spectra with uncorrected and polynomial baseline (PB)-corrected equivalents via three statistical applications: (1) clustering analysis, (2) functional group quantification

  9. 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

  10. Chemical characteristics of ambient aerosols contributed by cooking process at Noorpur village near New Delhi

    NASA Astrophysics Data System (ADS)

    Singh, Sudha

    Generally, industrial and transport sectors are considered as major contributors of air pollution but recently, biomass burning is also reported as a major source of atmospheric aerosols (1, 2) especially in the developing world where solid fuels such as dung cake, wood and crop residues are used in traditional cooking which are responsible for poor air quality, respiratory problems and radiative forcing etc .In India, most of the research has been focused on emission estimates from biomass burning and cooking. No effort has been made to understand the chemistry and sources of fine aerosols in rural areas during cooking hours. This study fills this knowledge gap and strengthens our understanding about abundance of various chemical constituents of atmospheric aerosols emitted during cooking hours.Aerosol samples were collected from village called Noorpur (28.470 N, 77.030 E) which lies near Delhi city. Sampling was carried out during August 2011-May 2012 by using handy sampler (Envirotech model APM 821) installed at the terrace of a building (~6m). The aerosol samples were collected on 8 hourly basis at a flow rate of 1 LPM. Water extracts of these filters were analyzed for major anions (F-, Cl-, NO3-, SO42-) and major cations (Na+, NH4+, K+, Ca2+ Mg2+) by ion chromatography (Metrohm 883 Basic IC Plus). During cooking period, the concentration of the major ions followed the order of Ca2+> SO42-> NO3-> Cl-> K+> NH4+> Mg2+> Na2+> F-. Among anion SO42 (5 µg/m3) showed highest value and in case of cations Ca2+ (7.32µg/m3) has highest value.

  11. The Collection 6 'dark-target' MODIS Aerosol Products

    NASA Technical Reports Server (NTRS)

    Levy, Robert C.; Mattoo, Shana; Munchak, Leigh A.; Kleidman, Richard G.; Patadia, Falguni; Gupta, Pawan; Remer, Lorraine

    2013-01-01

    Aerosol retrieval algorithms are applied to Moderate resolution Imaging Spectroradiometer (MODIS) sensors on both Terra and Aqua, creating two streams of decade-plus aerosol information. Products of aerosol optical depth (AOD) and aerosol size are used for many applications, but the primary concern is that these global products are comprehensive and consistent enough for use in climate studies. One of our major customers is the international modeling comparison study known as AEROCOM, which relies on the MODIS data as a benchmark. In order to keep up with the needs of AEROCOM and other MODIS data users, while utilizing new science and tools, we have improved the algorithms and products. The code, and the associated products, will be known as Collection 6 (C6). While not a major overhaul from the previous Collection 5 (C5) version, there are enough changes that there are significant impacts to the products and their interpretation. In its entirety, the C6 algorithm is comprised of three sub-algorithms for retrieving aerosol properties over different surfaces: These include the dark-target DT algorithms to retrieve over (1) ocean and (2) vegetated-dark-soiled land, plus the (3) Deep Blue (DB) algorithm, originally developed to retrieve over desert-arid land. Focusing on the two DT algorithms, we have updated assumptions for central wavelengths, Rayleigh optical depths and gas (H2O, O3, CO2, etc.) absorption corrections, while relaxing the solar zenith angle limit (up to 84) to increase pole-ward coverage. For DT-land, we have updated the cloud mask to allow heavy smoke retrievals, fine-tuned the assignments for aerosol type as function of season location, corrected bugs in the Quality Assurance (QA) logic, and added diagnostic parameters such as topographic altitude. For DT-ocean, improvements include a revised cloud mask for thin-cirrus detection, inclusion of wind speed dependence in the retrieval, updates to logic of QA Confidence flag (QAC) assignment, and

  12. Aerosol collection and analysis using diffuse reflectance infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Samuels, Alan C.; Wong, Diane M.; Meyer, Gerald J.; Roelant, Geoffrey J.; Williams, Barry R.; Miles, Ronald W., Jr.; Manning, Christopher J.

    2004-08-01

    Infrared spectroscopy is routinely employed for the identification of organic molecules and, more recently, for the classification of biological materials. We have developed a sample collection method that facilitates infrared analysis of airborne particulates using a diffuse reflectance (DR) technique. Efforts are underway to extend the method to include simultaneous analysis of vapor phase organics by using adsorbent substrates compatible with the DR technique. This series of laboratory results provides proof-of-principle for both the sample collection and data collection processes. Signal processing of the DR spectra is shown to provide rapid qualitative identification of representative aerosol materials, including particulate matter commonly found in the environment. We compare the results for such materials as bacterial spores, pollens and molds, clays and dusts, smoke and soot. Background correction analysis is shown to be useful for differentiation and identification of these constituents. Issues relating to complex mixtures of environmental samples under highly variable conditions are considered. Instrumentation development and materials research are now underway with the aim of constructing a compact sampling system for near real-time monitoring of aerosol and organic pollutants. A miniature, tilt-compensated Fourier transform spectrometer will provide spectroscopic interrogation. A series of advanced digital signal processing methods are also under development to enhance the sensor package. The approach will be useful for industrial applications, chemical and biological agent detection, and environmental monitoring for chemical vapors, hazardous air pollutants, and allergens.

  13. Characterization of radicals and high-molecular weight species from alpha-pinene/ozone reaction and ambient aerosol samples

    NASA Astrophysics Data System (ADS)

    Pavlovic, Jelica

    .1, were obtained. For all samples, the fine PM 1--2.5 fraction accounts for the largest WSOC content (from 37% to 47%), while the ultrafine particles in PM<0.1 contribute the least to the WSOC content (19% to 29%). Spectroscopic measurements (UV-VIS and fluorescence) confirmed structural similarities with aquatic fulvic and hulic acids. However, absorption and emission maxima were shifted to lower wavelengths compared to aquatic standards, indicating the presence of lower MW species and a lower degree of aromaticity. Results showed that the samples collected during September and especially in October had higher MW and higher percentage of aromatic carbon when compared with samples collected during summer months (July/August). Spectroscopy results were confirmed with ESI/MS analysis. That analysis also confirmed presence of four different classes of compounds in ambient aerosols: carboxylic acids, poly-carboxylic acids, organosulfates, and organonitrates.

  14. Spectral Aerosol Extinction (SpEx): A New Instrument for In situ Ambient Aerosol Extinction Measurements Across the UV/Visible Wavelength Range

    NASA Technical Reports Server (NTRS)

    Jordan, C. E.; Anderson, B. E.; Beyersdorf, A. J.; Corr, C. A.; Dibb, J. E.; Greenslade, M. E.; Martin, R. F.; Moore, R. H.; Scheuer, E.; Shook, M. A.; Thornhill, K. L.; Troop, D.; Winstead, Edward L.; Ziemba, L. D.

    2015-01-01

    We introduce a new instrument for the measurement of in situ ambient aerosol extinction over the 300-700 nm wavelength range, the Spectral Aerosol Extinction (SpEx) instrument. This measurement capability is envisioned to complement existing in situ instrumentation, allowing for simultaneous measurement of the evolution of aerosol optical, chemical, and physical characteristics in the ambient environment. In this work, a detailed description of the instrument is provided along with characterization tests performed in the laboratory. Measured spectra of NO2 and polystyrene latex spheres agreed well with theoretical calculations. Good agreement was also found with simultaneous aerosol extinction measurements at 450, 530, and 630 nm using CAPS PMex instruments in a series of 22 tests including non-absorbing compounds, dusts, soot, and black and brown carbon analogs. SpEx can more accurately distinguish the presence of brown carbon from other absorbing aerosol due to its 300 nm lower wavelength limit compared to measurements limited to visible wavelengths. In addition, the spectra obtained by SpEx carry more information than can be conveyed by a simple power law fit that is typically defined by the use of Angstrom Exponents. Future improvements aim at lowering detection limits and ruggedizing the instrument for mobile operation.

  15. Evidence and Quantitation of Aromatic Organosulfates in Ambient Aerosols in Lahore, Pakistan

    NASA Astrophysics Data System (ADS)

    Stone, B. A.; Kundu, S.; Yu, G.; Keutsch, F. N.; Quraishi, T.

    2012-12-01

    Organosulfates are important components of secondary organic aerosol (SOA) in ambient atmospheres, yet their structures, abundances, and formation processes are not well understood. In this study, a new type of organosulfate with an aromatic carbon backbone is identified and quantified in fine particulate matter (PM2.5) in the heavily polluted megacity of Lahore, Pakistan. An authentic standard of benzyl sulfate was synthesized and confirmed the presence of this unique compound in aerosol samples using high-resolution time-of-flight tandem mass spectrometry. Benzyl sulfate was quantified using ultra-performance liquid chromatography (UPLC) with negative electrospray ionization triple quadrupole mass spectrometry (ESI-MS/MS). The highest monthly-average benzyl sulfate concentrations were recorded in January and November 2007 (0.50±0.11 ng m-3), whereas the lowest concentration was observed in July (0.05±0.02 ng m-3). Seasonal trends were consistent with synoptic meteorology, with maxima occurring during the dry season and minima during the monsoonal summer. Matrix effects were evaluated by comparison of results obtained by external calibration and the method of standard addition; a minor deviation was observed (<10%) and matrix effects were determined to be insignificant in benzyl sulfate quantitation. Although benzyl sulfate contributions to organic carbon were relatively small (<0.001%), it may be an important tracer for organosulfates derived from anthropogenic volatile organic compounds.

  16. Measurement of Fluorescence Spectra from Ambient Aerosol Particles Using Laser-induced Fluorescence Technique

    NASA Astrophysics Data System (ADS)

    Taketani, F.; Kanaya, Y.; Nakamura, T.; Moteki, N.; Takegawa, N.

    2011-12-01

    To obtain the information of composition of organic aerosol particles in atmosphere, we developed an instrument using laser-induced fluorescence (LIF) technique. To measure the fluorescence from a particle, we employed two lasers. Scattering light signal derived from a single particle upon crossing the 635nm-CW laser triggers the 266nm-pulsed laser to excite the particle. Fluorescence from the particle in the wavelength range 300-600nm is spectrally dispersed by a grating spectrometer and then detected by a 32-Ch photo-multiplier tube(PMT). The aerosol stream is surrounded by a coaxial sheath air flow and delivered to the optical chamber at atmospheric pressure. Using PSL particles with known sizes, we made a calibration curve to estimate particle size from scattering light intensity. With the current setup of the instrument we are able to detect both scattering and fluorescence from particles whose diameters are larger than 0.5um. Our system was able to differentiate particles composed of mono-aromatic species (e.g. Tryptophan) from those of Riboflavin, by their different fluorescence wavelengths. Also, measurements of fluorescence spectra of ambient particles were demonstrated in our campus in Yokosuka city, facing Tokyo bay in Japan. We obtained several types of florescence spectra in the 8 hours. Classification of the measured fluorescence spectra will be discussed in the presentation.

  17. Detection of biological particles in ambient air using Bio-Aerosol Mass Spectrometry

    SciTech Connect

    McJimpsey, E L; Steele, P T; Coffee, K R; Fergenson, D P; Riot, V J; Woods, B W; Gard, E E; Frank, M; Tobias, H J; Lebrilla, C

    2006-03-16

    The Bio-Aerosol Mass Spectrometry (BAMS) system is an instrument used for the real time detection and identification of biological aerosols. Particles are drawn from the atmosphere directly into vacuum and tracked as they scatter light from several continuous wave lasers. After tracking, the fluorescence of individual particles is excited by a pulsed 266nm or 355nm laser. Molecules from those particles with appropriate fluorescence properties are subsequently desorbed and ionized using a pulsed 266nm laser. Resulting ions are analyzed in a dual polarity mass spectrometer. During two field deployments at the San Francisco International Airport, millions of ambient particles were analyzed and a small but significant fraction were found to have fluorescent properties similar to Bacillus spores and vegetative cells. Further separation of non-biological background particles from potential biological particles was accomplished using laser desorption/ionization mass spectrometry. This has been shown to enable some level of species differentiation in specific cases, but the creation and observation of higher mass ions is needed to enable a higher level of specificity across more species. A soft ionization technique, matrix-assisted laser desorption/ionization (MALDI) is being investigated for this purpose. MALDI is particularly well suited for mass analysis of biomolecules since it allows for the generation of molecular ions from large mass compounds that would fragment under normal irradiation. Some of the initial results from a modified BAMS system utilizing this technique are described.

  18. In situ secondary organic aerosol formation from ambient pine forest air using an oxidation flow reactor

    DOE PAGESBeta

    Palm, Brett B.; Campuzano-Jost, Pedro; Ortega, Amber M.; Day, Douglas A.; Kaser, Lisa; Jud, Werner; Karl, Thomas; Hansel, Armin; Hunter, James F.; Cross, Eben S.; et al

    2016-03-08

    An oxidation flow reactor (OFR) is a vessel inside which the concentration of a chosen oxidant can be increased for the purpose of studying SOA formation and aging by that oxidant. During the BEACHON-RoMBAS (Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics & Nitrogen–Rocky Mountain Biogenic Aerosol Study) field campaign, ambient pine forest air was oxidized by OH radicals in an OFR to measure the amount of SOA that could be formed from the real mix of ambient SOA precursor gases, and how that amount changed with time as precursors changed. High OH concentrations and short residence times allowed formore » semicontinuous cycling through a large range of OH exposures ranging from hours to weeks of equivalent (eq.) atmospheric aging. A simple model is derived and used to account for the relative timescales of condensation of low-volatility organic compounds (LVOCs) onto particles; condensational loss to the walls; and further reaction to produce volatile, non-condensing fragmentation products. More SOA production was observed in the OFR at nighttime (average 3 µg m−3 when LVOC fate corrected) compared to daytime (average 0.9 µg m−3 when LVOC fate corrected), with maximum formation observed at 0.4–1.5 eq. days of photochemical aging. SOA formation followed a similar diurnal pattern to monoterpenes, sesquiterpenes, and toluene+p-cymene concentrations, including a substantial increase just after sunrise at 07:00 local time. Higher photochemical aging (> 10 eq. days) led to a decrease in new SOA formation and a loss of preexisting OA due to heterogeneous oxidation followed by fragmentation and volatilization. When comparing two different commonly used methods of OH production in OFRs (OFR185 and OFR254-70), similar amounts of SOA formation were observed. We recommend the OFR185 mode for future forest studies. Concurrent gas-phase measurements of air after OH oxidation illustrate the decay of primary VOCs, production of

  19. In situ secondary organic aerosol formation from ambient pine forest air using an oxidation flow reactor

    NASA Astrophysics Data System (ADS)

    Palm, Brett B.; Campuzano-Jost, Pedro; Ortega, Amber M.; Day, Douglas A.; Kaser, Lisa; Jud, Werner; Karl, Thomas; Hansel, Armin; Hunter, James F.; Cross, Eben S.; Kroll, Jesse H.; Peng, Zhe; Brune, William H.; Jimenez, Jose L.

    2016-03-01

    An oxidation flow reactor (OFR) is a vessel inside which the concentration of a chosen oxidant can be increased for the purpose of studying SOA formation and aging by that oxidant. During the BEACHON-RoMBAS (Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics & Nitrogen-Rocky Mountain Biogenic Aerosol Study) field campaign, ambient pine forest air was oxidized by OH radicals in an OFR to measure the amount of SOA that could be formed from the real mix of ambient SOA precursor gases, and how that amount changed with time as precursors changed. High OH concentrations and short residence times allowed for semicontinuous cycling through a large range of OH exposures ranging from hours to weeks of equivalent (eq.) atmospheric aging. A simple model is derived and used to account for the relative timescales of condensation of low-volatility organic compounds (LVOCs) onto particles; condensational loss to the walls; and further reaction to produce volatile, non-condensing fragmentation products. More SOA production was observed in the OFR at nighttime (average 3 µg m-3 when LVOC fate corrected) compared to daytime (average 0.9 µg m-3 when LVOC fate corrected), with maximum formation observed at 0.4-1.5 eq. days of photochemical aging. SOA formation followed a similar diurnal pattern to monoterpenes, sesquiterpenes, and toluene+p-cymene concentrations, including a substantial increase just after sunrise at 07:00 local time. Higher photochemical aging (> 10 eq. days) led to a decrease in new SOA formation and a loss of preexisting OA due to heterogeneous oxidation followed by fragmentation and volatilization. When comparing two different commonly used methods of OH production in OFRs (OFR185 and OFR254-70), similar amounts of SOA formation were observed. We recommend the OFR185 mode for future forest studies. Concurrent gas-phase measurements of air after OH oxidation illustrate the decay of primary VOCs, production of small oxidized organic

  20. In situ secondary organic aerosol formation from ambient pine forest air using an oxidation flow reactor

    NASA Astrophysics Data System (ADS)

    Palm, B. B.; Campuzano-Jost, P.; Ortega, A. M.; Day, D. A.; Kaser, L.; Jud, W.; Karl, T.; Hansel, A.; Hunter, J. F.; Cross, E. S.; Kroll, J. H.; Peng, Z.; Brune, W. H.; Jimenez, J. L.

    2015-11-01

    Ambient air was oxidized by OH radicals in an oxidation flow reactor (OFR) located in a montane pine forest during the BEACHON-RoMBAS campaign to study biogenic secondary organic aerosol (SOA) formation and aging. High OH concentrations and short residence times allowed for semi-continuous cycling through a large range of OH exposures ranging from hours to weeks of equivalent (eq.) atmospheric aging. A simple model is derived and used to account for the relative time scales of condensation of low volatility organic compounds (LVOCs) onto particles, condensational loss to the walls, and further reaction to produce volatile, non-condensing fragmentation products. More SOA production was observed in the OFR at nighttime (average 4 μg m-3 when LVOC fate corrected) compared to daytime (average 1 μg m-3 when LVOC fate corrected), with maximum formation observed at 0.4-1.5 eq. days of photochemical aging. SOA formation followed a similar diurnal pattern to monoterpenes, sesquiterpenes, and toluene + p-cymene concentrations, including a substantial increase just after sunrise at 07:00 LT. Higher photochemical aging (> 10 eq. days) led to a decrease in new SOA formation and a loss of preexisting OA due to heterogeneous oxidation followed by fragmentation and volatilization. When comparing two different commonly used methods of OH production in OFRs (OFR185 and OFR254), similar amounts of SOA formation were observed. We recommend the OFR185 mode for future forest studies. Concurrent gas-phase measurements of air after OH oxidation illustrate the decay of primary VOCs, production of small oxidized organic compounds, and net production at lower ages followed by net consumption of terpenoid oxidation products as photochemical age increased. New particle formation was observed in the reactor after oxidation, especially during times when precursor gas concentrations and SOA formation were largest. Approximately 6 times more SOA was formed in the reactor from OH oxidation than

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  2. Molecular markers in ambient aerosol in the Mahanadi Riverside Basin of eastern central India during winter.

    PubMed

    Nirmalkar, Jayant; Deb, Manas K; Deshmukh, Dhananjay K; Tsai, Ying I; Verma, Santosh K

    2015-01-01

    Organic molecular markers are important atmospheric constituents. Their formation and sources are important aspects of the study of urban and rural air quality. We collected PM10 aerosol samples from the Mahanadi Riverside Basin (MRB), a rural part of eastern central India, during the winter of 2011. PM10 aerosols were characterized for molecular markers using ion chromatography. The concentration of PM10 ranged from 208.8 to 588.3 μg m(-3) with a mean concentration of 388.9 μg m(-3). Total concentration of anhydrosugars, sugar alcohols, primary sugars, and oxalate were found to be 3.25, 5.60, 10.52, and 0.37 μg m(-3), respectively, during the study period. Glucose was the most abundant species followed by levoglucosan and mannitol. Significant positive correlation between the molecular markers, anhydrosugars, sugar alcohols, primary sugars, and oxalic acid confirmed that biomass burning, biogenic activity, and re-suspension of soil particles were the main sources of aerosol in the eastern central India study area. PMID:25131681

  3. Characterization of Primary Organic Aerosol Emissions from Meat Cooking, Trash Burning, and Combustion Engines with High-Resolution Aerosol Mass Spectrometry and Comparison with Ambient and Chamber Observations

    NASA Astrophysics Data System (ADS)

    Mohr, C.; Huffman, J. A.; Cubison, M. J.; Aiken, A. C.; Docherty, K. S.; Kimmel, J. R.; Ulbrich, I. M.; Hannigan, M.; Garcia, J.; Jimenez, J. L.

    2009-04-01

    Organic aerosol (OA) emissions from motor vehicles, meat-cooking and trash burning are analyzed here using a high-resolution aerosol mass spectrometer (AMS) and supporting instrumentation. A semi-quantitative comparison of emission factors highlights the potential importance of meat cooking as an OA source. GC-MS and AMS mass spectra are compared for the first time and show high similarity, but with more fragmentation in the AMS due to higher vaporization temperatures. High resolution data show that aerosols emitted by combustion engines and plastic burning are dominated by hydrocarbon-like organic compounds. Meat cooking and especially paper burning contain significant fractions of oxygenated organic compounds; however, their unit-resolution mass spectral signatures are very similar to mass spectral signatures from hydrocarbon-like OA or primary OA, and very different from the mass spectra of ambient secondary or oxygenated OA (OOA). Thus, primary OA from any of these sources is very unlikely to be a significant direct source of ambient OOA. There are significant differences in high-resolution tracer m/z's that may be useful for differentiating these sources from each other. Unlike in most ambient spectra, all of these sources have low total m/z 44 and this signal is not dominated by the CO2+ ion. All sources have high m/z 57, which is low during high OOA ambient periods. Spectra from paper burning are similar to some types of biomass burning OA, with elevated m/z 60. Meat cooking aerosols also have slightly elevated m/z 60, while motor vehicle emissions have very low signal at this m/z.

  4. The source identification of ambient aerosols in Beijing, China by multivariate analysis coupled with {sup 14}C tracer

    SciTech Connect

    Xiaoyan Tang; Min Shao; Yuanhang Zhang

    1996-12-31

    Ambient aerosol is one of most important pollutants in China. This paper showed the results of aerosol sources of Beijing area revealed by combination of multivariate analysis models and 14C tracer measured on Accelerator Mass Spectrometry (AMS). The results indicated that the mass concentration of particulate (<100 (M)) didn`t increase rapidly, compared with economic development in Beijing city. The multivariate analysis showed that the predominant source was soil dust which contributed more than 50% to atmospheric particles. However, it would be a risk to conclude that the aerosol pollution from anthropogenic sources was less important in Beijing city based on above phenomenon. Due to lack of reliable tracers, it was very hard to distinguish coal burning from soil source. Thus, it was suspected that the soil source above might be the mixture of soil dust and coal burning. The 14C measurement showed that carbonaceous species of aerosol had quite different emission sources. For carbonaceous aerosols in Beijing, the contribution from fossil fuel to ambient particles was nearly 2/3, as the man-made activities ( coal-burning, etc.) increased, the fossil part would contribute more to atmospheric carbonaceous particles. For example, in downtown Beijing at space-heating seasons, the fossil fuel even contributed more than 95% to carbonaceous particles, which would be potential harmful to population. By using multivariate analysis together with 14C data, two important sources of aerosols in Beijing (soil and coal) combustion were more reliably distinguished, which was critical important for the assessment of aerosol problem in China.

  5. A concept of an automated function control for ambient aerosol measurements using mobility particle size spectrometers

    NASA Astrophysics Data System (ADS)

    Bastian, S.; Löschau, G.; Wiedensohler, A.

    2014-04-01

    An automated function control unit was developed to regularly check the ambient particle number concentration derived from a mobility particle size spectrometer as well as its zero-point behaviour. The function control allows unattended quality assurance experiments at remote air quality monitoring or research stations under field conditions. The automated function control also has the advantage of being able to get a faster system stability response than the recommended on-site comparisons with reference instruments. The method is based on a comparison of the total particle number concentration measured by a mobility particle size spectrometer and a condensation particle counter while removing diffusive particles smaller than 20 nm in diameter. In practice, the small particles are removed by a set of diffusion screens, as traditionally used in a diffusion battery. Another feature of the automated function control is to check the zero-point behaviour of the ambient aerosol passing through a high-efficiency particulate air (HEPA) filter. The performance of the function control is illustrated with the aid of a 1-year data set recorded at Annaberg-Buchholz, a station in the Saxon air quality monitoring network. During the period of concern, the total particle number concentration derived from the mobility particle size spectrometer slightly overestimated the particle number concentration recorded by the condensation particle counter by 2 % (grand average). Based on our first year of experience with the function control, we developed tolerance criteria that allow a performance evaluation of a tested mobility particle size spectrometer with respect to the total particle number concentration. We conclude that the automated function control enhances the quality and reliability of unattended long-term particle number size distribution measurements. This will have beneficial effects for intercomparison studies involving different measurement sites, and help provide a higher

  6. A concept of an automated function control for ambient aerosol measurements using mobility particle size spectrometers

    NASA Astrophysics Data System (ADS)

    Schladitz, A.; Merkel, M.; Bastian, S.; Birmili, W.; Weinhold, K.; Löschau, G.; Wiedensohler, A.

    2013-12-01

    An automated function control unit was developed to regularly check the ambient particle number concentration derived from a mobility particle size spectrometer as well as its zero-point behaviour. The aim of the new feature is to conduct unattended quality control experiments under field conditions at remote air quality monitoring or research stations. The automated function control also has the advantage of being able to get a faster system stability response than the recommended on-site comparisons with reference instruments. The method is based on a comparison of the total particle number concentration measured by a mobility particle size spectrometer and a condensation particle counter removing the diffusive particles approximately smaller than 25 nm in diameter. In practice, the small particles are removed by a set of diffusion screens, as traditionally used in a diffusion battery. The other feature of the automated function control is to check the zero-point behaviour of the ambient aerosol passing through a high-efficiency particulate air (HEPA) filter. An exemplary one-year data set is presented for the measurement site Annaberg-Buchholz as part of the Saxon air quality monitoring network. The total particle number concentration derived from the mobility particle size spectrometer overestimates the particle number concentration by only 2% (grand average offset). Furthermore, tolerance criteria are presented to judge the performance of the mobility particle size spectrometer with respect to the particle number concentration. An upgrade of a mobility particle size spectrometer with an automated function control enhances the quality of long-term particle number size distribution measurements. Quality assured measurements are a precondition for intercomparison studies of different sites. Comparable measurements will improve cohort health and also climate-relevant research studies.

  7. Evaporation kinetics and phase of laboratory and ambient secondary organic aerosol.

    PubMed

    Vaden, Timothy D; Imre, Dan; Beránek, Josef; Shrivastava, Manish; Zelenyuk, Alla

    2011-02-01

    Field measurements of secondary organic aerosol (SOA) find significantly higher mass loads than predicted by models, sparking intense effort focused on finding additional SOA sources but leaving the fundamental assumptions used by models unchallenged. Current air-quality models use absorptive partitioning theory assuming SOA particles are liquid droplets, forming instantaneous reversible equilibrium with gas phase. Further, they ignore the effects of adsorption of spectator organic species during SOA formation on SOA properties and fate. Using accurate and highly sensitive experimental approach for studying evaporation kinetics of size-selected single SOA particles, we characterized room-temperature evaporation kinetics of laboratory-generated α-pinene SOA and ambient atmospheric SOA. We found that even when gas phase organics are removed, it takes ∼24 h for pure α-pinene SOA particles to evaporate 75% of their mass, which is in sharp contrast to the ∼10 min time scale predicted by current kinetic models. Adsorption of "spectator" organic vapors during SOA formation, and aging of these coated SOA particles, dramatically reduced the evaporation rate, and in some cases nearly stopped it. Ambient SOA was found to exhibit evaporation behavior very similar to that of laboratory-generated coated and aged SOA. For all cases studied in this work, SOA evaporation behavior is nearly size-independent and does not follow the evaporation kinetics of liquid droplets, in sharp contrast with model assumptions. The findings about SOA phase, evaporation rates, and the importance of spectator gases and aging all indicate that there is need to reformulate the way SOA formation and evaporation are treated by models.

  8. Dependence of Aerosol Light Absorption and Single-Scattering Albedo On Ambient Relative Humidity for Sulfate Aerosols with Black Carbon Cores

    NASA Technical Reports Server (NTRS)

    Redemann, Jens; Russell, Philip B.; Hamill, Patrick

    2001-01-01

    Atmospheric aerosols frequently contain hygroscopic sulfate species and black carbon (soot) inclusions. In this paper we report results of a modeling study to determine the change in aerosol absorption due to increases in ambient relative humidity (RH), for three common sulfate species, assuming that the soot mass fraction is present as a single concentric core within each particle. Because of the lack of detailed knowledge about various input parameters to models describing internally mixed aerosol particle optics, we focus on results that were aimed at determining the maximum effect that particle humidification may have on aerosol light absorption. In the wavelength range from 450 to 750 nm, maximum absorption humidification factors (ratio of wet to 'dry=30% RH' absorption) for single aerosol particles are found to be as large as 1.75 when the RH changes from 30 to 99.5%. Upon lesser humidification from 30 to 80% RH, absorption humidification for single particles is only as much as 1.2, even for the most favorable combination of initial ('dry') soot mass fraction and particle size. Integrated over monomodal lognormal particle size distributions, maximum absorption humidification factors range between 1.07 and 1.15 for humidification from 30 to 80% and between 1.1 and 1.35 for humidification from 30 to 95% RH for all species considered. The largest humidification factors at a wavelength of 450 nm are obtained for 'dry' particle size distributions that peak at a radius of 0.05 microns, while the absorption humidification factors at 700 nm are largest for 'dry' size distributions that are dominated by particles in the radius range of 0.06 to 0.08 microns. Single-scattering albedo estimates at ambient conditions are often based on absorption measurements at low RH (approx. 30%) and the assumption that aerosol absorption does not change upon humidification (i.e., absorption humidification equal to unity). Our modeling study suggests that this assumption alone can

  9. Estimate of biogenic VOC emissions in Japan and their effects on photochemical formation of ambient ozone and secondary organic aerosol

    NASA Astrophysics Data System (ADS)

    Chatani, Satoru; Matsunaga, Sou N.; Nakatsuka, Seiji

    2015-11-01

    A new gridded database has been developed to estimate the amount of isoprene, monoterpene, and sesquiterpene emitted from all the broadleaf and coniferous trees in Japan with the Model of Emissions of Gases and Aerosols from Nature (MEGAN). This database reflects the vegetation specific to Japan more accurately than existing ones. It estimates much lower isoprene emitted from other vegetation than trees, and higher sesquiterpene emissions mainly emitted from Cryptomeria japonica, which is the most abundant plant type in Japan. Changes in biogenic emissions result in the decrease in ambient ozone and increase in organic aerosol simulated by the air quality simulation over the Tokyo Metropolitan Area in Japan. Although newly estimated biogenic emissions contribute to a better model performance on overestimated ozone and underestimated organic aerosol, they are not a single solution to solve problems associated with the air quality simulation.

  10. Real-time analysis of ambient organic aerosols using aerosol flowing atmospheric-pressure afterglow mass spectrometry (AeroFAPA-MS)

    NASA Astrophysics Data System (ADS)

    Brüggemann, Martin; Karu, Einar; Stelzer, Torsten; Hoffmann, Thorsten

    2015-04-01

    Organic aerosol accounts for a major fraction of atmospheric aerosols and has implications on the earth's climate and human health. However, due to the chemical complexity its measurement remains a major challenge for analytical instrumentation.1 Here, we present the development, characterization and application of a new soft ionization technique that allows mass spectrometric real-time detection of organic compounds in ambient aerosols. The aerosol flowing atmospheric-pressure afterglow (AeroFAPA) ion source utilizes a helium glow discharge plasma to produce excited helium species and primary reagent ions. Ionization of the analytes occurs in the afterglow region after thermal desorption and results mainly in intact molecular ions, facilitating the interpretation of the acquired mass spectra. In the past, similar approaches were used to detect pesticides, explosives or illicit drugs on a variety of surfaces.2,3 In contrast, the AeroFAPA source operates 'online' and allows the detection of organic compounds in aerosols without a prior precipitation or sampling step. To our knowledge, this is the first application of an atmospheric-pressure glow discharge ionization technique to ambient aerosol samples. We illustrate that changes in aerosol composition and concentration are detected on the time scale of seconds and in the ng-m-3 range. Additionally, the successful application of AeroFAPA-MS during a field study in a mixed forest region in Central Europe is presented. Several oxidation products of monoterpenes were clearly identified using the possibility to perform tandem MS experiments. The acquired data are in agreement with previous studies and demonstrate that AeroFAPA-MS is a suitable tool for organic aerosol analysis. Furthermore, these results reveal the potential of this technique to enable new insights into aerosol formation, growth and transformation in the atmosphere. References: 1) IPCC, 2013: Summary for Policymakers. In: Climate Change 2013: The

  11. Ambient temperature and the occurrence of collective violence: the "long, hot summer" revisited.

    PubMed

    Baron, R A; Ransberger, V M

    1978-04-01

    Archival data pertaining to 102 instances of serious collective violence were examined in order to study the relationship between ambient temperature and the occurrence of such events. Results indicated that the frequency of collective violence and ambient temperature were curvilinearly related. Specifically, ambient temperature was directly associated with the frequency of collective violence through the mid-80s (degrees Fahrenheit). Beyond this point, however, further increments in temperature were associated with a decreasing incidence of such events. Additional findings indicated that ambient temperature increased significantly during the 7 days preceding the outbreak of collective violence, remained stable during its occurrence, but then decreased significantly in the 3 days following its termination. Possible implications of these findings, as well as their relationship to the results of previous laboratory studies, are discussed.

  12. The ambient organic aerosol soluble in water: Measurements, chemical characterization, and an investigation of sources

    NASA Astrophysics Data System (ADS)

    Sullivan, Amy P.

    This thesis characterizes the ambient fine organic carbon (OC) aerosol and investigates its sources through the development and deployment of new analytical measurement techniques. Recognizing that OC is highly chemically complex, the approach was to develop methods capable of quantitatively measuring a large chemical fraction of the aerosol instead of specific chemical speciation. The focus is on organic compounds that are soluble in water (WSOC) since little is known about its chemical nature. The results from this thesis show that WSOC has mainly two sources: biomass burning and secondary organic aerosol (SOA). In urban areas, WSOC increases with plume age, and tracks other photochemically produced compounds. Chemical analysis of WSOC suggests that in urban Atlanta, the SOA is mainly small-chain aliphatic compounds indirectly linked to vehicle emissions. A method was first developed for quantitative on-line measurements of WSOC by extending the application of the Particle-into-Liquid Sampler (PILS) from inorganic to organic aerosol measurements. In this approach a PILS captures ambient particles into a flow of purified water, which is then forced through a liquid filter and the carbonaceous content quantified on-line by a Total Organic Carbon (TOC) analyzer. An instrument was first developed for ground-based measurements and then modified for airborne deployment. Ground-based measurements at the St. Louis - Midwest Supersite during the summer of 2003 showed that the fraction of OC that is water-soluble can have a highly diurnal pattern with WSOC to OC ratios reaching 0.80 during the day and lows of 0.40 during the night. During extended periods under stagnation pollution events, this pattern was well correlated with ozone concentrations. The results are consistent with formation of SOA. Airborne PILS-TOC measurements from the NOAA WP-3D during the New England Air Quality Study/Intercontinental Transport and Chemical Transformation (NEAQS/ITCT) 2004 program

  13. Volatility and lifetime against OH heterogeneous reaction of ambient isoprene-epoxydiols-derived secondary organic aerosol (IEPOX-SOA)

    DOE PAGESBeta

    Hu, Weiwei; Palm, Brett B.; Day, Douglas A.; Campuzano-Jost, Pedro; Krechmer, Jordan E.; Peng, Zhe; de Sá, Suzane S.; Martin, Scot T.; Alexander, M. Lizabeth; Baumann, Karsten; et al

    2016-09-19

    Isoprene-epoxydiols-derived secondary organic aerosol (IEPOX-SOA) can contribute substantially to organic aerosol (OA) concentrations in forested areas under low NO conditions, hence significantly influencing the regional and global OA budgets, accounting, for example, for 16–36 % of the submicron OA in the southeastern United States (SE US) summer. Particle evaporation measurements from a thermodenuder show that the volatility of ambient IEPOX-SOA is lower than that of bulk OA and also much lower than that of known monomer IEPOX-SOA tracer species, indicating that IEPOX-SOA likely exists mostly as oligomers in the aerosol phase. The OH aging process of ambient IEPOX-SOA was investigated withmore » an oxidation flow reactor (OFR). New IEPOX-SOA formation in the reactor was negligible, as the OFR does not accelerate processes such as aerosol uptake and reactions that do not scale with OH. Simulation results indicate that adding  ∼  100 µg m−3 of pure H2SO4 to the ambient air allows IEPOX-SOA to be efficiently formed in the reactor. The heterogeneous reaction rate coefficient of ambient IEPOX-SOA with OH radical (kOH) was estimated as 4.0 ± 2.0  ×  10−13 cm3 molec−1 s−1, which is equivalent to more than a 2-week lifetime. A similar kOH was found for measurements of OH oxidation of ambient Amazon forest air in an OFR. At higher OH exposures in the reactor (>  1  ×  1012 molec cm−3 s), the mass loss of IEPOX-SOA due to heterogeneous reaction was mainly due to revolatilization of fragmented reaction products. We report, for the first time, OH reactive uptake coefficients (γOH =  0.59 ± 0.33 in SE US and γOH =  0.68 ± 0.38 in Amazon) for SOA under ambient conditions. A relative humidity dependence of kOH and γOH was observed, consistent with surface-area-limited OH uptake. No decrease of kOH was observed as OH concentrations increased. These observations of physicochemical

  14. Volatility and lifetime against OH heterogeneous reaction of ambient isoprene-epoxydiols-derived secondary organic aerosol (IEPOX-SOA)

    NASA Astrophysics Data System (ADS)

    Hu, Weiwei; Palm, Brett B.; Day, Douglas A.; Campuzano-Jost, Pedro; Krechmer, Jordan E.; Peng, Zhe; de Sá, Suzane S.; Martin, Scot T.; Lizabeth Alexander, M.; Baumann, Karsten; Hacker, Lina; Kiendler-Scharr, Astrid; Koss, Abigail R.; de Gouw, Joost A.; Goldstein, Allen H.; Seco, Roger; Sjostedt, Steven J.; Park, Jeong-Hoo; Guenther, Alex B.; Kim, Saewung; Canonaco, Francesco; Prévôt, André S. H.; Brune, William H.; Jimenez, Jose L.

    2016-09-01

    Isoprene-epoxydiols-derived secondary organic aerosol (IEPOX-SOA) can contribute substantially to organic aerosol (OA) concentrations in forested areas under low NO conditions, hence significantly influencing the regional and global OA budgets, accounting, for example, for 16-36 % of the submicron OA in the southeastern United States (SE US) summer. Particle evaporation measurements from a thermodenuder show that the volatility of ambient IEPOX-SOA is lower than that of bulk OA and also much lower than that of known monomer IEPOX-SOA tracer species, indicating that IEPOX-SOA likely exists mostly as oligomers in the aerosol phase. The OH aging process of ambient IEPOX-SOA was investigated with an oxidation flow reactor (OFR). New IEPOX-SOA formation in the reactor was negligible, as the OFR does not accelerate processes such as aerosol uptake and reactions that do not scale with OH. Simulation results indicate that adding ˜ 100 µg m-3 of pure H2SO4 to the ambient air allows IEPOX-SOA to be efficiently formed in the reactor. The heterogeneous reaction rate coefficient of ambient IEPOX-SOA with OH radical (kOH) was estimated as 4.0 ± 2.0 × 10-13 cm3 molec-1 s-1, which is equivalent to more than a 2-week lifetime. A similar kOH was found for measurements of OH oxidation of ambient Amazon forest air in an OFR. At higher OH exposures in the reactor (> 1 × 1012 molec cm-3 s), the mass loss of IEPOX-SOA due to heterogeneous reaction was mainly due to revolatilization of fragmented reaction products. We report, for the first time, OH reactive uptake coefficients (γOH = 0.59 ± 0.33 in SE US and γOH = 0.68 ± 0.38 in Amazon) for SOA under ambient conditions. A relative humidity dependence of kOH and γOH was observed, consistent with surface-area-limited OH uptake. No decrease of kOH was observed as OH concentrations increased. These observations of physicochemical properties of IEPOX-SOA can help to constrain OA impact on air quality and climate.

  15. Seasonal variations and sources of ambient fossil and biogenic-derived carbonaceous aerosols based on 14C measurements in Lhasa, Tibet

    NASA Astrophysics Data System (ADS)

    Huang, Jie; Kang, Shichang; Shen, Chengde; Cong, Zhiyuan; Liu, Kexin; Wang, Wei; Liu, Lichao

    2010-06-01

    A total of 30 samples of total suspended particles were collected at an urban site in Lhasa, Tibet from August 2006 to July 2007 for investigating carbonaceous aerosol features. The fractions of contemporary carbon ( fc) in total carbon (TC) of ambient aerosols are presented using radiocarbon ( 14C) measurements. The value of fc represents the biogenic contribution to TC, as the biosphere releases organic compounds with the present 14C/ 12C level ( fc = 1), whereas 14C has become extinct in anthropogenic emissions of fossil carbon ( fc = 0). The fc values in Lhasa ranging from 0.357 to 0.702, are higher than Beijing and Tokyo, but clearly lower than the rural region of Launceston, which indicates a major biogenic influence in Lhasa. Seasonal variations of fc values corresponded well with variations of pollutants concentrations (e.g. NO 2). Higher fc values appeared in winter indicating carbonaceous aerosol is more dominated by wood burning and incineration of agricultural wastes within this season. The lower fc values in summer and autumn may be caused by increased diesel and petroleum emissions related to tourism in Lhasa. δ13C values ranged from - 26.40‰ to - 25.10‰, with relative higher values in spring and summer, reflecting the increment of fossil carbon emissions.

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

    NASA Astrophysics Data System (ADS)

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

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

  17. Human health benefits of ambient sulfate aerosol reductions under Title IV of the 1990 Clean Air Act amendments

    SciTech Connect

    Chestnut, L.G.; Watkins, A.M.

    1997-12-31

    The Acid Rain Provisions (Title IV) of the Clean Air Act Amendments of 1990 call for about a 10 million ton reduction in annual SO{sub 2} emissions in the United States by the year 2010. Although the provisions apply nationwide, most of the reduction will take place in the eastern half of the United States, where use of high sulfur coal for electricity generation is most common. One potentially large benefit of Title IV is the expected reduction in adverse human health effects associated with exposure to ambient sulfate aerosols, a secondary pollutant formed in the atmosphere when SO{sub 2} is present. Sulfate aerosols are a significant constituent of fine particulate (PM{sub 2.5}). This paper combines available epidemiologic evidence of health effects associated with sulfate aerosols and economic estimates of willingness to pay for reductions in risks or incidence of health effects with available estimates of the difference between expected ambient sulfate concentrations in the eastern United States and southeastern Canada with and without Title IV to estimate the expected health benefits of Title IV. The results suggest a mean annual benefit in the eastern United States of $10.6 billion (in 1994 dollars) in 1997 and $40.0 billion in 2010, with an additional $1 billion benefit each year in Ontario and Quebec provinces.

  18. 2-Hydroxyterpenylic acid: An oxygenated marker compound for a-pinene secondary organic aerosol in ambient fine aerosol

    EPA Science Inventory

    An oxygenated MW 188 compound is commonly observed in substantial abundance in atmospheric aerosol samples and was proposed in previous studies as an α-pinene-related marker compound that is associated with aging processes. Owing to difficulties in producing this compound in suff...

  19. 78 FR 25078 - Information Collection Request Submitted to OMB for Review and Approval; Comment Request; Ambient...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-29

    ... network design information. The U.S. EPA and others (e.g., State and local air quality management agencies... AGENCY Information Collection Request Submitted to OMB for Review and Approval; Comment Request; Ambient.... SUMMARY: The Environmental Protection Agency has submitted an information collection request...

  20. 78 FR 57631 - Information Collection Request Submitted to OMB for Review and Approval; Comment Request; Ambient...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-19

    ... network design information. The EPA and others (e.g., State and local air quality management agencies... AGENCY Information Collection Request Submitted to OMB for Review and Approval; Comment Request; Ambient.... SUMMARY: The Environmental Protection Agency has submitted an information collection request...

  1. High-Resolution Electrospray Ionization Mass Spectrometry Analysis of Water- Soluble Organic Aerosols Collected with a Particle into Liquid Sampler

    SciTech Connect

    Bateman, Adam P.; Nizkorodov, Serguei; Laskin, Julia; Laskin, Alexander

    2010-10-01

    This work demonstrates the utility of a particle-into-liquid sampler (PILS) a technique traditionally used for identification of inorganic ions present in ambient or laboratory aerosols for the analysis of water soluble organic aerosol (OA) using high resolution electrospray ionization mass spectrometry (HR ESI-MS). Secondary organic aerosol (SOA) was produced from 0.5 ppm mixing ratios of limonene and ozone in a 5 m3 Teflon chamber. SOA was collected simultaneously using a traditional filter sampler and a PILS. The filter samples were later extracted with either water or acetonitrile, while the aqueous PILS samples were analyzed directly. In terms of peak intensities, types of detectable compounds, average O:C ratios, and organic mass to organic carbon ratios, the resulting high resolution mass spectra were essentially identical for the PILS and filter based samples. SOA compounds extracted from both filter/acetonitrile extraction and PILS/water extraction accounted for >95% of the total ion current in ESI mass spectra. This similarity was attributed to high solubility of limonene SOA in water. In contrast, significant differences in detected ions and peak abundances were observed for pine needle biomass burning organic aerosol (BBOA) collected with PILS and filter sampling. The water soluble fraction of BBOA is considerably smaller than for SOA, and a number of unique peaks were detectable only by the filter/acetonitrile method. The combination of PILS collection with HR-ESI-MS analysis offers a new approach for molecular analysis of the water-soluble organic fraction in biogenic SOA, aged photochemical smog, and BBOA.

  2. Light scattering characteristics of aerosols at ambient and as a function of relative humidity: Part II--A comparison of measured scattering and aerosol concentrations using statistical models.

    PubMed

    Malm, W C; Day, D E; Kreidenweis, S M

    2000-05-01

    The eastern United States national parks experience some of the worst visibility conditions in the nation. To study these conditions, the Southeastern Aerosol and Visibility Study (SEAVS) was undertaken to characterize the size-dependent composition, thermodynamic properties, and optical characteristics of the ambient atmospheric particles. It is a cooperative three-year study that is sponsored by the National Park Service and the Electric Power Research Institute and its member utilities. The field portion of the study was carried out from July 15 to August 25, 1995. The study design, instrumental configuration, and estimation of aerosol types from particle measurements is presented in a companion paper. In the companion paper, we compare measurements of scattering at ambient conditions and as functions of relative humidity to theoretical predictions of scattering. In this paper, we make similar comparisons, but using statistical techniques. Statistically derived specific scattering associated with sulfates suggest that a reasonable estimate of sulfate scattering can be arrived at by assuming nominal dry specific scattering and treating the aerosols as an external mixture with ammoniation of sulfate accounted for and by the use of Tang's growth curves to predict water absorption. However, the regressions suggest that the sulfate scattering may be underestimated by about 10%. Regression coefficients on organics, to within the statistical uncertainty of the model, suggest that a reasonable estimate of organic scattering is about 4.0 m2/g. A new analysis technique is presented, which does not rely on comparing measured to model estimates of scattering to evoke an understanding of ambient aerosol growth properties, but rather relies on measurements of scattering as a function of relative humidity to develop actual estimates of f(RH) curves. The estimates of the study average f(RH) curve for sulfates compares favorably with the theoretical f(RH) curve for ammonium

  3. CHARACTERIZATION OF AMBIENT PM2.5 AEROSOL AT A SOUTHEASTERN US SITE: FOURIER TRANSFORM INFRARED ANALYSIS OR PARTICLE PHASE

    EPA Science Inventory

    During a field study in the summer of 2000 in the Research Triangle Park (RTP), aerosol samples were collected using a five stage cascade impactor and subsequently analyzed using Fourier Transform Infrared Spectroscopy (FTIR). The impaction surfaces were stainless steel disks....

  4. The MODIS Aerosol Algorithm: Critical Evaluation and Plans for Collection 6

    NASA Technical Reports Server (NTRS)

    Remer, Lorraine

    2010-01-01

    For ten years the MODIS aerosol algorithm has been applied to measured MODIS radiances to produce a continuous set of aerosol products, over land and ocean. The MODIS aerosol products are widely used by the scientific and applied science communities for variety of purposes that span operational air quality forecasting in estimates o[ clear-sky direct radiative effects over ocean and aerosol-cloud interactions. The products undergo continual evaluation, including self-consistency checks and comparisons with highly accurate ground-based instruments. The result of these evaluation exercises is a quantitative understanding of the strengths and weaknesses of the retrieval, where and when the products are accurate and the situations where and when accuracy degrades. We intend 10 present results of the most recent critical evaluations including the first comparison of the over ocean products against the shipboard aerosol optical depth measurements of the Marine Aerosol Network (MAN), the demonstration of the lack of sensitivity to size parameter in the over land products and identification of residual problems and regional issues. While the current data set is undergoing evaluation, we are preparing for the next data processing, labeled Collection 6. Collection 6 will include transparent Quality Flags, a 3 km aerosol product and the 500m resolution cloud mask used within the aerosol n:bicvu|. These new products and adjustments to algorithm assumptions should provide users with more options and greater control, as they adapt the product for their own purposes.

  5. Speciation of Water-Soluble Organic Carbons in Aerosols from two collecting methods: PILS and filters

    NASA Astrophysics Data System (ADS)

    Kim, J.; Yoon, H.; Ahn, Y.; Shin, J.; Lee, M.; Park, M.

    2013-12-01

    Total suspended particles aerosol sampling for collection of 24 h by high volume air sampler at Campus of Korea University in metropolitan city Seoul. To measure WSOC, an aliquot (2 cm2) of quartz fiber filter ( 20.3 × 25.4 cm) was extracted 5 mL Milli-Q water with hot water (80 °C) and room temperature water (25 °C) under ultrasonication (10 min, three times). Hot water extracted method was comparison with PILS samples. WSOC was quantified using a total organic carbon (TOC) analyzer. For speciation analysis of organic compounds, the extracts were concentrated to dryness using freeze dryer and then derivatized with MSTFA (N-Methyl-N-trimethy- silyltrifluoroacetamide+1% trimethylchlorosilane) and analyzed with GC-MS scan mode. In extracted with hot water, total carbon concentrations were higher than room temperature extracts. Organic compounds widely recognized to be generated from anthropogenic sources with a low solubility at ambient temperature organic were detected in both samples obtained from PILS and hot water extraction. It is demonstrating that difference between total carbon concentration and composition of sampling obtain from two different systems (i.e. PILS and filter) in analytical procedure of WSOCs. Acknowledgement This research was susported by Center for Women In Science, Engineering Technology(WISET) commissioned by the Ministry of Science, ICT & Future Planning and the National Research Foundation of korea. The authors also acknowledge the support made by a grant from the Korea Basic Science Institute.

  6. Ambient measurements of biological aerosol particles near Killarney, Ireland: a comparison between real-time fluorescence and microscopy techniques

    NASA Astrophysics Data System (ADS)

    Healy, D. A.; Huffman, J. A.; O'Connor, D. J.; Pöhlker, C.; Pöschl, U.; Sodeau, J. R.

    2014-02-01

    Primary biological aerosol particles (PBAP) can contribute significantly to the coarse particle burden in many environments, may thus influence climate and precipitation systems as cloud nuclei, and can spread disease to humans, animals, and plants. Measurements of PBAP in natural environments taken at high time- and size- resolution are, however, sparse and so large uncertainties remain in the role that biological particles play in the Earth system. In this study two commercial real-time fluorescence particle sensors and a Sporewatch single-stage particle impactor were operated continuously from 2 August to 2 September 2010 at a rural sampling location in Killarney National Park in south western Ireland. A cascade impactor was operated periodically to collect size-resolved particles during exemplary periods. Here we report the first ambient comparison of the waveband integrated bioaerosol sensor (WIBS-4) with the ultraviolet aerodynamic particle sizer (UV-APS) and also compare these real-time fluorescence techniques with results of fluorescence and optical microscopy of impacted samples. Both real-time instruments showed qualitatively similar behaviour, with increased fluorescent bioparticle concentrations at night when relative humidity was highest and temperature was lowest. The fluorescent particle number from the FL3 channel of the WIBS-4 and from the UV-APS were strongly correlated and dominated by a 3 μm mode in the particle size distribution. The WIBS FL2 channel exhibited particle modes at approx. 1 and 3 μm, and each were correlated with the concentration of fungal spores commonly observed in air samples collected at the site (ascospores, basidiospores, Ganoderma spp.). The WIBS FL1 channel exhibited variable multi-modal distributions turning into a broad featureless single mode after averaging and exhibited poor correlation with fungal spore concentrations, which may be due to the detection of bacterial and non-biological fluorescent particles

  7. Ambient measurements of biological aerosol particles near Killarney, Ireland: a comparison between real-time fluorescence and microscopy techniques

    NASA Astrophysics Data System (ADS)

    Healy, D. A.; Huffman, J. A.; O'Connor, D. J.; Pöhlker, C.; Pöschl, U.; Sodeau, J. R.

    2014-08-01

    Primary biological aerosol particles (PBAPs) can contribute significantly to the coarse particle burden in many environments. PBAPs can thus influence climate and precipitation systems as cloud nuclei and can spread disease to humans, animals, and plants. Measurement data and techniques for PBAPs in natural environments at high time- and size resolution are, however, sparse, and so large uncertainties remain in the role that biological particles play in the Earth system. In this study two commercial real-time fluorescence particle sensors and a Sporewatch single-stage particle impactor were operated continuously from 2 August to 2 September 2010 at a rural sampling location in Killarney National Park in southwestern Ireland. A cascade impactor was operated periodically to collect size-resolved particles during exemplary periods. Here we report the first ambient comparison of a waveband integrated bioaerosol sensor (WIBS-4) with a ultraviolet aerodynamic particle sizer (UV-APS) and also compare these real-time fluorescence techniques with results of fluorescence and optical microscopy of impacted samples. Both real-time instruments showed qualitatively similar behavior, with increased fluorescent bioparticle concentrations at night, when relative humidity was highest and temperature was lowest. The fluorescent particle number from the FL3 channel of the WIBS-4 and from the UV-APS were strongly correlated and dominated by a 3 μm mode in the particle size distribution. The WIBS FL2 channel exhibited particle modes at approx. 1 and 3 μm, and each was correlated with the concentration of fungal spores commonly observed in air samples collected at the site (ascospores, basidiospores, Ganoderma spp.). The WIBS FL1 channel exhibited variable multimodal distributions turning into a broad featureless single mode after averaging, and exhibited poor correlation with fungal spore concentrations, which may be due to the detection of bacterial and non-biological fluorescent

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  9. EVALUATION OF COMPUTER-CONTROLLED SCANNING ELECTRON MICROSCOPY APPLIED TO AN AMBIENT URBAN AEROSOL SAMPLE

    EPA Science Inventory

    Concerns about the environmental and public health effects of particulate matter (PM) have stimulated interest in analytical techniques capable of measuring the size and chemical composition of individual aerosol particles. Computer-controlled scanning electron microscopy (CCSE...

  10. Ambient Observations of Organic Nitrogen Compounds in Submicrometer Aerosols in New York Using High Resolution Aerosol Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Zhou, S.; Ge, X.; Xu, J.; Sun, Y.; Zhang, Q.

    2015-12-01

    Organic nitrogen (ON) compounds, which include amines, nitriles, organic nitrates, amides, and N-containing aromatic heterocycles, are an important class of compounds ubiquitously detected in atmospheric particles and fog and cloud droplets. Previous studies indicate that these compounds can make up a significant fraction (20-80%) of the total nitrogen (N) content in atmospheric condensed phases and play important roles in new particle formation and growth and affecting the optical and hygroscopicity of aerosols. In this study, we report the observation of ON compounds in submicrometer particles (PM1) at two locations in New York based on measurements using Aerodyne high-resolution time-of-flight mass spectrometer (HR-ToF-AMS). One study was conducted as part of the US Department of Energy funded Aerosol Lifecyle - Intensive Operation Period (ALC-IOP) campaign at Brookhaven National Lab (BNL, 40.871˚N, 72.89˚W) in summer, 2011 and the other was conducted at the Queen's College (QC) in New York City (NYC) in summer, 2009. We observed a notable amount of N-containing organic fragment ions, CxHyNp+ and CxHyOzNp+, in the AMS spectra of organic aerosols at both locations and found that they were mainly associated with amino functional groups. Compared with results from lab experiments, the C3H8N+ at m/z = 58 was primarily attributed to trimethylamine. In addition, a significant amount of organonitrates was observed at BNL. Positive matrix factorization (PMF) analysis of the high resolution mass spectra (HRMS) of organic aerosols identified a unique nitrogen-enriched OA (NOA) factor with elevated nitrogen-to-carbon (N/C) at both BNL and QC. Analysis of the size distributions, volatility profiles, and correlations with external tracer indicates that acid-base reactions of amino compounds with sulfate and acidic gas were mainly responsible for the formation of amine salts. Photochemical production was also observed to play a role in the formation of NOA. Bivariate polar

  11. An automated online instrument to quantify aerosol-bound reactive oxygen species (ROS) for ambient measurement and health-relevant aerosol studies

    NASA Astrophysics Data System (ADS)

    Wragg, Francis P. H.; Fuller, Stephen J.; Freshwater, Ray; Green, David C.; Kelly, Frank J.; Kalberer, Markus

    2016-10-01

    The adverse health effects associated with ambient aerosol particles have been well documented, but it is still unclear which aerosol properties are most important for their negative health impact. Some studies suggest the oxidative effects of particle-bound reactive oxygen species (ROS) are potential major contributors to the toxicity of particles. Traditional ROS measurement techniques are labour-intensive, give poor temporal resolution and generally have significant delays between aerosol sampling and ROS analysis. However, many oxidising particle components are reactive and thus potentially short-lived. Thus, a technique to quantify particle-bound ROS online would be beneficial to quantify also the short-lived ROS components. We introduce a new portable instrument to allow online, continuous measurement of particle-bound ROS using a chemical assay of 2'7'-dichlorofluorescein (DCFH) with horseradish peroxidase (HRP), via fluorescence spectroscopy. All components of the new instrument are attached to a containing shell, resulting in a compact system capable of automated continuous field deployment over many hours or days. From laboratory measurements, the instrument was found to have a detection limit of ˜ 4 nmol [H2O2] equivalents per cubic metre (m3) air, a dynamic range up to at least ˜ 2000 nmol [H2O2] equivalents per m3 air and a time resolution of ≤ 12 min. The instrument allows for ˜ 16 h automated measurement if unattended and shows a fast response to changes in concentrations of laboratory-generated oxidised organic aerosol. The instrument was deployed at an urban site in London, and particulate ROS levels of up to 24 nmol [H2O2] equivalents per m3 air were detected with PM2.5 concentrations up to 28 µg m-3. The new and portable Online Particle-bound ROS Instrument (OPROSI) allows fast-response quantification; this is important due to the potentially short-lived nature of particle-bound ROS as well as fast-changing atmospheric conditions

  12. Development of a double-layered ceramic filter for aerosol filtration at high-temperatures: the filter collection efficiency.

    PubMed

    de Freitas, Normanda L; Gonçalves, José A S; Innocentini, Murilo D M; Coury, José R

    2006-08-25

    The performance of double-layered ceramic filters for aerosol filtration at high temperatures was evaluated in this work. The filtering structure was composed of two layers: a thin granular membrane deposited on a reticulate ceramic support of high porosity. The goal was to minimize the high pressure drop inherent of granular structures, without decreasing their high collection efficiency for small particles. The reticulate support was developed using the technique of ceramic replication of polyurethane foam substrates of 45 and 75 pores per inch (ppi). The filtering membrane was prepared by depositing a thin layer of granular alumina-clay paste on one face of the support. Filters had their permeability and fractional collection efficiency analyzed for filtration of an airborne suspension of phosphatic rock in temperatures ranging from ambient to 700 degrees C. Results revealed that collection efficiency decreased with gas temperature and was enhanced with filtration time. Also, the support layer influenced the collection efficiency: the 75 ppi support was more effective than the 45 ppi. Particle collection efficiency dropped considerably for particles below 2 microm in diameter. The maximum collection occurred for particle diameters of approximately 3 microm, and decreased again for diameters between 4 and 8 microm. Such trend was successfully represented by the proposed correlation, which is based on the classical mechanisms acting on particle collection. Inertial impaction seems to be the predominant collection mechanism, with particle bouncing/re-entrainment acting as detachment mechanisms.

  13. Fast oxidation processes from emission to ambient air introduction of aerosol emitted by residential log wood stoves

    NASA Astrophysics Data System (ADS)

    Nalin, Federica; Golly, Benjamin; Besombes, Jean-Luc; Pelletier, Charles; Aujay-Plouzeau, Robin; Verlhac, Stéphane; Dermigny, Adrien; Fievet, Amandine; Karoski, Nicolas; Dubois, Pascal; Collet, Serge; Favez, Olivier; Albinet, Alexandre

    2016-10-01

    Little is known about the impact of post-combustion processes, condensation and dilution, on the aerosol concentration and chemical composition from residential wood combustion. The evolution of aerosol emitted by two different residential log wood stoves (old and modern technologies) from emission until it is introduced into ambient air was studied under controlled "real" conditions. The first objective of this research was to evaluate the emission factors (EF) of polycyclic aromatic hydrocarbons (PAH) and their nitrated and oxygenated derivatives from wood combustion. These toxic substances are poorly documented in the literature. A second objective was to evaluate the oxidation state of the wood combustion effluent by studying these primary/secondary compounds. EFs of Σ37PAHs and Σ27Oxy-PAHs were in the same range and similar to those reported in literature (4-240 mg kg-1). Σ31Nitro-PAH EFs were 2-4 orders of magnitude lower (3.10-2-8.10-2 mg kg-1) due to the low temperature and low emission of NO2 from wood combustion processes. An increase of equivalent EF of PAH derivatives was observed suggesting that the oxidation state of the wood combustion effluent from the emission point until its introduction in ambient air changed in a few seconds. These results were confirmed by the study of both, typical compounds of SOA formation from PAH oxidation and, PAH ratio-ratio plots commonly used for source evaluation.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  15. Oxidative potential of secondary organic aerosols produced from photooxidation of different hydrocarbons using outdoor chamber under ambient sunlight

    NASA Astrophysics Data System (ADS)

    Jiang, Huanhuan; Jang, Myoseon; Sabo-Attwood, Tara; Robinson, Sarah E.

    2016-04-01

    The oxidative potential of various secondary organic aerosols (SOA) was measured using dithiothreitol (DTT) assay to understand how organic aerosols react with cellular materials. SOA was produced via the photooxidation of four different hydrocarbons (toluene, 1,3,5-trimethylbenzene, isoprene and α-pinene) in the presence of NOx using a large outdoor photochemical smog chamber. The DTT consumption rate was normalized by the aerosol mass, which is expressed as DTTmass. Toluene SOA and isoprene SOA yielded higher DTTmass than 1,3,5-trimethylbenzene SOA or α-pinene SOA. In order to discover the correlation between the molecular structure and oxidative potential, the DTT responses of selected model compounds were also measured. Among them, conjugated aldehydes, quinones, and H2O2 showed considerable DTT response. To investigate the correlation between DTT response and cell responses in vitro, the expression of biological markers, i.e. IL-6, IL-8, and HMOX-1 were studied using small airway epithelial cells. Higher cellular expression of IL-8 was observed with toluene SOA exposure compared to 1,3,5-trimethylbenzene SOA exposure, which aligned with the results from DTT assay. Our study also suggests that within the urban atmosphere, the contribution of toluene SOA and isoprene SOA to the oxidative potential of ambient SOA will be more significant than that of α-pinene SOA.

  16. FORMATION OF 2-METHYL TETROLS AND 2-METHYLGLYCERIC ACID IN SECONDARY ORGANIC AEROSOL FROM LABORATORY IRRADIATED ISOPRENE/NO X/SO 2/AIR MIXTURES AND THEIR DETECTION IN AMBIENT PM 2.5 SAMPLES COLLECTED IN THE EASTERN UNITED STATES

    EPA Science Inventory

    A series of isoprene/NOx/air irradiation experiments, carried out in both the absence and presence of SO2, were conducted to assess whether isoprene contributes to secondary organic aerosol (SOA) formation. In the absence of SO2 , the SOA yield of 0.002 was low. However, in th...

  17. An assessment of the performance of the Monitor for AeRosols and GAses in ambient air (MARGA): a semi-continuous method for soluble compounds

    NASA Astrophysics Data System (ADS)

    Rumsey, I. C.; Cowen, K.; Kelly, T.; Hanft, E.; Mishoe, K.; Rogers, C.; Proost, R.; Lear, G.; Frelink, T.; Walker, J. T.

    2011-12-01

    Ambient air monitoring as part of the U.S. EPA's Clean Air Status and Trends Network (CASTNet) currently uses filter packs to measure weekly integrated concentrations. The U.S. EPA is interested in supplementing CASTNet with semi-continuous monitoring systems at select sites to examine ecosystem exposure to nitrogen and sulfur compounds at higher time resolution and with greater accuracy than the filter pack. The Monitor for AeRosols and GAses in ambient air (MARGA) measures water-soluble gases and aerosols at hourly temporal resolution. The performance of the MARGA was assessed under the U.S. EPA Environmental Technology Verification (ETV) program. The assessment was conducted in Research Triangle Park, NC from September 8th-October 8th, 2010. Precision of the MARGA was evaluated by comparing duplicate units and accuracy was evaluated by comparing duplicate MARGAs to duplicate reference denuder/filter packs. The MARGA utilizes a Wet Rotating Denuder (WRD) to collect gases, while aerosols are collected by a Steam Jet Aerosol Collector (SJAC). Both the WRD and the SJAC produce aqueous sample streams, which are analyzed by online ion chromatography for anions and cations. The reference denuder/filter pack consisted of sodium carbonate (Na2CO3) and phosphorous acid (H3PO3) coated denuders followed by a Teflon filter, a nylon filter, and a citric acid coated cellulose filter. The assessment of the MARGA units focused on gaseous SO2, HNO3 and NH3 and aerosol SO4-, NO3- and NH4+. To evaluate accuracy, hourly MARGA concentrations were averaged over 12 hours to match with 12-hour integrated concentrations from the reference system. The concentrations were compared using linear regression with performance goals of slope between 0.8-1.2 and y-intercept between -10 ppb and 10 ppb. Accuracy was further quantified as the median absolute relative percent difference (MARPD) between 12-hour MARGA and reference concentrations, with a performance goal of ≤ 40%. The precision of

  18. Photoacoustic and filter-based ambient aerosol light absorption measurements: Instrument comparisons and the role of relative humidity

    NASA Astrophysics Data System (ADS)

    Arnott, W. P.; Moosmüller, H.; Sheridan, P. J.; Ogren, J. A.; Raspet, R.; Slaton, W. V.; Hand, J. L.; Kreidenweis, S. M.; Collett, J. L.

    2003-01-01

    Ambient measurements are reported of aerosol light absorption from photoacoustic and filter-based instruments (aethalometer and a particle soot absorption photometer (PSAP)) to provide insight on the measurement science. Measurements were obtained during the Big Bend Regional Aerosol and Visibility Observational Study at the Big Bend National Park in South Texas. The aethalometer measurements of black carbon concentration at this site correlate reasonably well with photoacoustic measurements of aerosol light absorption, with a slope of 8.1 m2/g and a small offset. Light absorption at this site never exceeded 2.1 Mm-1 during the month of collocated measurements. Measurements were also obtained, as a function of controlled relative humidity between 40% and 90%, during the Photoacoustic IOP in 2000 at the Department of Energy Southern Great Plains Cloud and Radiation Testbed site (SGP). PSAP measurements of aerosol light absorption correlated very well with photoacoustic measurements, but the slope of the correlation indicated the PSAP values were larger by a factor of 1.61. The photoacoustic measurements of light absorption exhibited a systematic decrease when the RH increased beyond 70%. This apparent decrease in light absorption with RH may be due to the contribution of mass transfer to the photoacoustic signal. Model results for the limiting case of full water saturation are used to evaluate this hypothesis. A second PSAP measured the light absorption for the same humidified samples, and indicated very erratic response as the RH changed, suggesting caution when interpreting PSAP data under conditions of rapid relative humidity change.

  19. Secondary Organic Aerosol Formation from Ambient Air in an Oxidation Flow Reactor at GoAmazon2014/5

    NASA Astrophysics Data System (ADS)

    Palm, Brett B.; de Sa, Suzane S.; Campuzano-Jost, Pedro; Day, Douglas A.; Hu, Weiwei; Seco, Roger; Park, Jeong-Hoo; Guenther, Alex; Kim, Saewung; Brito, Joel; Wurm, Florian; Artaxo, Paulo; Yee, Lindsay; Isaacman-VanWertz, Gabrial; Goldstein, Allen; Newburn, Matt K.; Lizabeth Alexander, M.; Martin, Scot T.; Brune, William H.; Jimenez, Jose L.

    2016-04-01

    During GoAmazon2014/5, ambient air was exposed to controlled concentrations of OH or O3 in situ using an oxidation flow reactor (OFR). Oxidation ranged from hours-several weeks of aging. Oxidized air was sampled by several instruments (e.g., HR-AMS, ACSM, PTR-TOF-MS, SMPS, CCN) at both the T3 site (IOP1: Feb 1-Mar 31, 2014, and IOP2: Aug 15-Oct 15, 2014) and T2 site (between IOPs and into 2nd IOP). The oxidation of ambient air in the OFR led to substantial and variable secondary organic aerosol (SOA) formation from any SOA-precursor gases, known and unknown, that entered the OFR. In general, more SOA was produced during the nighttime than daytime, suggesting that SOA-precursor gases were found in relatively higher concentrations at night. Similarly, more SOA was formed in the dry season (IOP2) than wet season (IOP1). The maximum amount of SOA produced during nighttime from OH oxidation ranged from less than 1 μg/m3 on some nights to greater than 10 μg/m3 on other nights. O3 oxidation of ambient air also led to SOA formation, although several times less than from OH oxidation. The amount of SOA formation sometimes, but not always, correlated with measured gas-phase biogenic and/or anthropogenic SOA precursors (e.g., SV-TAG sesquiterpenes, PTR-TOFMS aromatics, isoprene, and monoterpenes). The SOA mass formed in the OFR from OH oxidation was up to an order of magnitude larger than could be explained from aerosol yields of measured primary VOCs. This along with measurements from previous campaigns suggests that most SOA was formed from intermediate S/IVOC sources (e.g., VOC oxidation products, evaporated POA, or direct emissions). To verify the SOA yields of VOCs under OFR experimental conditions, atmospherically-relevant concentrations of several VOCs were added individually into ambient air in the OFR and oxidized by OH or O3. SOA yields in the OFR were similar to published chamber yields. Preliminary PMF factor analysis showed production of secondary factors in

  20. Long-term trends in California mobile source emissions and ambient concentrations of black carbon and organic aerosol.

    PubMed

    McDonald, Brian C; Goldstein, Allen H; Harley, Robert A

    2015-04-21

    A fuel-based approach is used to assess long-term trends (1970-2010) in mobile source emissions of black carbon (BC) and organic aerosol (OA, including both primary emissions and secondary formation). The main focus of this analysis is the Los Angeles Basin, where a long record of measurements is available to infer trends in ambient concentrations of BC and organic carbon (OC), with OC used here as a proxy for OA. Mobile source emissions and ambient concentrations have decreased similarly, reflecting the importance of on- and off-road engines as sources of BC and OA in urban areas. In 1970, the on-road sector accounted for ∼90% of total mobile source emissions of BC and OA (primary + secondary). Over time, as on-road engine emissions have been controlled, the relative importance of off-road sources has grown. By 2010, off-road engines were estimated to account for 37 ± 20% and 45 ± 16% of total mobile source contributions to BC and OA, respectively, in the Los Angeles area. This study highlights both the success of efforts to control on-road emission sources, and the importance of considering off-road engine and other VOC source contributions when assessing long-term emission and ambient air quality trends. PMID:25793355

  1. Long-term trends in California mobile source emissions and ambient concentrations of black carbon and organic aerosol.

    PubMed

    McDonald, Brian C; Goldstein, Allen H; Harley, Robert A

    2015-04-21

    A fuel-based approach is used to assess long-term trends (1970-2010) in mobile source emissions of black carbon (BC) and organic aerosol (OA, including both primary emissions and secondary formation). The main focus of this analysis is the Los Angeles Basin, where a long record of measurements is available to infer trends in ambient concentrations of BC and organic carbon (OC), with OC used here as a proxy for OA. Mobile source emissions and ambient concentrations have decreased similarly, reflecting the importance of on- and off-road engines as sources of BC and OA in urban areas. In 1970, the on-road sector accounted for ∼90% of total mobile source emissions of BC and OA (primary + secondary). Over time, as on-road engine emissions have been controlled, the relative importance of off-road sources has grown. By 2010, off-road engines were estimated to account for 37 ± 20% and 45 ± 16% of total mobile source contributions to BC and OA, respectively, in the Los Angeles area. This study highlights both the success of efforts to control on-road emission sources, and the importance of considering off-road engine and other VOC source contributions when assessing long-term emission and ambient air quality trends.

  2. Stable carbon isotope ratios of ambient secondary organic aerosols in Toronto

    NASA Astrophysics Data System (ADS)

    Saccon, M.; Kornilova, A.; Huang, L.; Moukhtar, S.; Rudolph, J.

    2015-09-01

    A method to quantify concentrations and stable carbon isotope ratios of secondary organic aerosols has been applied to study atmospheric nitrophenols in Toronto, Canada. The sampling of five nitrophenols, all with substantial secondary formation from the photooxidation of aromatic volatile organic compounds (VOCs), was conducted in the gas phase and particulate matter (PM) together and in PM alone. Their concentrations in the atmosphere are in the low ng m-3 range and, consequently, a large volume of air (> 1000 m3) is needed to analyze samples for stable carbon isotope ratios, resulting in sampling periods of typically 24 h. While this extended sampling period increases the representativeness of average values, it at the same time reduces possibilities to identify meteorological conditions or atmospheric pollution levels determining nitrophenol concentrations and isotope ratios. Average measured carbon isotope ratios of the different nitrophenols are between -34 and -33 ‰, which is well within the range predicted by mass balance. However, the observed carbon isotope ratios cover a range of nearly 9 ‰ and approximately 20 % of the isotope ratios of the products have isotope ratios lower than predicted from the kinetic isotope effect of the first step of the reaction mechanism and the isotope ratio of the precursor. This can be explained by isotope fractionation during reaction steps following the initial reaction of the precursor VOCs with the OH radical. Limited evidence for local production of nitrophenols is observed since sampling was done in the Toronto area, an urban center with significant anthropogenic emission sources. Strong evidence for significant local formation of nitrophenols is only found for samples collected in summer. On average, the difference in carbon isotope ratios between nitrophenols in the particle phase and in the gas phase is insignificant, but for a limited number of observations in summer, a substantial difference is observed. This

  3. Stable carbon isotope ratios of ambient secondary organic aerosols in Toronto

    NASA Astrophysics Data System (ADS)

    Saccon, M.; Kornilova, A.; Huang, L.; Moukhtar, S.; Rudolph, J.

    2015-06-01

    A method to quantify concentrations and stable carbon isotope ratios of secondary organic aerosols (SOA) has been applied to study atmospheric nitrophenols in Toronto, Canada. The sampling of five nitrophenols, all primarily formed from the photo-oxidation of aromatic volatile organic compounds (VOC), in the gas phase and particulate matter (PM) together and PM alone was conducted. Since all of the target compounds are secondary products, their concentrations in the atmosphere are in the low ng m-3 range and consequently a large volume of air (> 1000 m3) is needed to analyze samples for stable carbon isotope ratios, resulting in sampling periods of typically 24 h. While this extended sampling period increases the representativeness of average values, it at the same time reduces possibilities to identify meteorological conditions or atmospheric pollution levels determining nitrophenol concentrations and isotope ratios. Average measured carbon isotope ratios of the different nitrophenols are between -34 and -33‰, which is well within the range predicted by mass balance calculations. However, the observed carbon isotope ratios cover a range of nearly 9‰, and approximately 20% of the isotope ratios of the products have isotope ratios lower than predicted from the kinetic isotope effect of the first step of the reaction mechanism and the isotope ratio of the precursor. This can be explained by isotope fractionation during reaction steps following the initial reaction of the precursor VOCs with the OH radical. Limited evidence for local production of nitrophenols is observed since sampling was done in the Toronto area, an urban centre with significant anthropogenic emission sources. Strong evidence for significant local formation of nitrophenols is only found for samples collected in summer. On average, the difference in carbon isotope ratios between nitrophenols in the particle phase and in the gas phase is insignificant, but for a limited number of observations in

  4. Aerosols attenuating the solar radiation collected by solar tower plants: The horizontal pathway at surface level

    NASA Astrophysics Data System (ADS)

    Elias, Thierry; Ramon, Didier; Dubus, Laurent; Bourdil, Charles; Cuevas-Agulló, Emilio; Zaidouni, Taoufik; Formenti, Paola

    2016-05-01

    Aerosols attenuate the solar radiation collected by solar tower plants (STP), along two pathways: 1) the atmospheric column pathway, between the top of the atmosphere and the heliostats, resulting in Direct Normal Irradiance (DNI) changes; 2) the grazing pathway close to surface level, between the heliostats and the optical receiver. The attenuation along the surface-level grazing pathway has been less studied than the aerosol impact on changes of DNI, while it becomes significant in STP of 100 MW or more. Indeed aerosols mostly lay within the surface atmospheric layer, called the boundary layer, and the attenuation increases with the distance covered by the solar radiation in the boundary layer. In STP of 100 MW or more, the distance between the heliostats and the optical receiver becomes large enough to produce a significant attenuation by aerosols. We used measured aerosol optical thickness and computed boundary layer height to estimate the attenuation of the solar radiation at surface level at Ouarzazate (Morocco). High variabilities in aerosol amount and in vertical layering generated a significant magnitude in the annual cycle and significant inter-annual changes. Indeed the annual mean of the attenuation caused by aerosols over a 1-km heliostat-receiver distance was 3.7% in 2013, and 5.4% in 2014 because of a longest desert dust season. The monthly minimum attenuation of less than 3% was observed in winter and the maximum of more than 7% was observed in summer.

  5. SMOG CHAMBER STUDIES OF SECONDARY ORGANIC AEROSOLS FROM IRRADIATED HYDROCARBONS UNDER AMBIENT CONDITIONS

    EPA Science Inventory

    Understanding the physics and chemistry of aerosols is fundamental to evaluating health risks and developing and evaluating atmospheric models. However, as noted in a recent NRC report only about 10% of the organics in PM2.5 have been identified. A significant portion of the un...

  6. Library Optimization in EDXRF Spectral Deconvolution for Multi-element Analysis of Ambient Aerosols

    EPA Science Inventory

    In multi-element analysis of atmospheric aerosols, attempts are made to fit overlapping elemental spectral lines for many elements that may be undetectable in samples due to low concentrations. Fitting with many library reference spectra has the unwanted effect of raising the an...

  7. Quantitative extraction of organic tracer compounds from ambient particulate matter collected on polymer substrates.

    PubMed

    Sun, Qinyue; Alexandrova, Olga A; Herckes, Pierre; Allen, Jonathan O

    2009-05-15

    Organic compounds in ambient particulate matter (PM) samples are used as tracers for PM source apportionment. These PM samples are collected using high volume samplers; one such sampler is an impactor in which polyurethane foam (PUF) and polypropylene foam (PPF) are used as the substrates. The polymer substrates have the advantage of limiting particle bounce artifacts during sampling; however these substrates may contain background organic additives. A protocol of two extractions with isopropanol followed by three extractions with dichloromethane (DCM) was developed for both substrate precleaning and analyte extraction. Some residual organic contaminants were present after precleaning; expressed as concentrations in a 24-h ambient PM sample, the residual amounts were 1 microg m(-3) for plasticizers and antioxidants, and 10 ng m(-3) for n-alkanes with carbon number lower than 26. The quantification limit for all other organic tracer compounds was approximately 0.1 ng m(-3) in a 24-h ambient PM sample. Recovery experiments were done using NIST Standard Reference Material (SRM) Urban Dust (1649a); the average recoveries for polycyclic aromatic hydrocarbons (PAHs) from PPF and PUF substrates were 117+/-8% and 107+/-11%, respectively. Replicate extractions were also done using the ambient samples collected in Nogales, Arizona. The relative differences between repeat analyses were less than 10% for 47 organic tracer compounds quantified. After the first extraction of ambient samples, less than 7% of organic tracer compounds remained in the extracted substrates. This method can be used to quantify a suite of semi- and non-polar organic tracer compounds suitable for source apportionment studies in 24-h ambient PM samples.

  8. Heterogeneous reaction of peroxyacetic acid and hydrogen peroxide on ambient aerosol particles under dry and humid conditions: kinetics, mechanism and implications

    NASA Astrophysics Data System (ADS)

    Wu, Q. Q.; Huang, L. B.; Liang, H.; Zhao, Y.; Huang, D.; Chen, Z. M.

    2015-06-01

    Hydrogen peroxide (H2O2) and organic peroxides play important roles in the cycle of oxidants and the formation of secondary aerosols in the atmosphere. Recent field observations have suggested that the budget of peroxyacetic acid (PAA, CH3C(O)OOH) is potentially related to the aerosol phase processes, especially to secondary aerosol formation. Here, we present the first laboratory measurements of the uptake coefficient of gaseous PAA and H2O2 onto ambient fine particulate matter (PM2.5) as a function of relative humidity (RH) at 298 K. The results show that the PM2.5, which was collected in an urban area, can take up PAA and H2O2 at the uptake coefficient (γ) of 10-4, and both γPAA and γH2O2 increase with increasing RH. The value of γPAA at 90 % RH is 5.4 ± 1.9 times that at 3 % RH, whereas γH2O2 at 90 % RH is 2.4 ± 0.5 times that at 3 % RH, which suggests that PAA is more sensitive to the RH variation than H2O2 is. Considering the larger Henry's law constant of H2O2 than that of PAA, the smaller RH sensitivity of the H2O2 uptake coefficient suggests that the enhanced uptake of peroxide compounds on PM2.5 under humid conditions is dominated by chemical processes rather than dissolution. Considering that mineral dust is one of the main components of PM2.5 in Beijing, we also determined the uptake coefficients of gaseous PAA and H2O2 on authentic Asian Dust storm (ADS) and Arizona Test Dust (ATD) particles. Compared to ambient PM2.5, ADS shows a similar γ value and RH dependence in its uptake coefficient for PAA and H2O2, while ATD gives a negative dependence on RH. The present study indicates that, in addition to the mineral dust in PM2.5, other components (e.g., soluble inorganic salts) are also important to the uptake of peroxide compounds. When the heterogeneous reaction of PAA on PM2.5 is considered, its atmospheric lifetime is estimated to be 3.0 h on haze days and 7.1 h on non-haze days, values that are in good agreement with the field observations.

  9. ANALYSIS OF RESPIRATORY DEPOSITION OF INHALED PARTICLES FOR DIFFERENT DOSE METRICS: COMPARISON OF NUMBER, SURFACE AREA AND MASS DOSE OF TYPICAL AMBIENT BI-MODAL AEROSOLS

    EPA Science Inventory

    ANALYSIS OF RESPIRATORY DEPOSITION OF INHALED PARTICLES FOR DIFFERENT DOSE METRICS: COMPARISON OF NUMBER, SURFACE AREA AND MASS DOSE OF TYPICAL AMBIENT BI-MODAL AEROSOLS.
    Chong S. Kim, SC. Hu*, PA Jaques*, US EPA, National Health and Environmental Effects Research Laboratory, ...

  10. Comparison of three methods for measuring light absorption by collected aerosols.

    PubMed

    Ramsey-Bell, D C; Couture, G

    1985-08-01

    Three instruments for measuring absorption of visible light by atmospheric aerosols are compared: the visual comparator; plate diffuser; and photoacoustic spectrometer. Two versions of the photoacoustic spectrometer are tested, one built of acrylic plastic and the other of aluminum. One version of the visual comparator uses Millipore filters for a crucial reflective surface, another a mirror. Several materials collected on Nuclepore filters are used in the comparison. Laboratory generated samples consist of carbon and carbon overlaid with ammonium sulfate. Atmospheric aerosols were collected in Tucson and on an Arizona mountain peak. All methods give reasonably consistent results, even when applied to the lightly absorbing nonurban atmospheric samples. PMID:18223896

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  12. Thermal desorption single particle mass spectrometry of ambient aerosol in Shanghai

    NASA Astrophysics Data System (ADS)

    Zhai, Jinghao; Wang, Xinning; Li, Jingyan; Xu, Tingting; Chen, Hong; Yang, Xin; Chen, Jianmin

    2015-12-01

    Submicron aerosol volatility, chemical composition, and mixing state were simultaneously measured using a thermodenuder (TD) in-line with a single particle aerosol mass spectrometry (SPAMS) during Nov.12 to Dec. 11 of 2014 in Shanghai. By heating up to 250 °C, the signals of refractory species such as elemental carbon, metallic compounds, and mineral dust in aerosols were enhanced in the mass spectra. At 250 °C, the main particle types present in the size range of 0.2-1.0 μm were biomass burning (37% by number) and elemental carbon (20%). From 1.0 to 2.0 μm, biomass burning (30%), dust (19%) and metal-rich (18%) were the primary particle types. CN- signal remained in the mass spectra of the heated biomass burning particles suggests the existence of some extremely low-volatility nitrogen-containing organics. Laboratory experiments were conducted by burning rice straws, the main source material of biomass burning particles in Southern China, to confirm the less volatile composition contributed by biomass burning. Strong CN- with relative area >0.21 was observed in most of the laboratory-made biomass burning particles when heated above 200 °C and was selected as a new marker to identify the biomass burning particles in the field. The TD-SPAMS measured the size-resolved chemical composition of the individual particle residues at different temperatures and offered more information on the aging processes of primary particles and their sources.

  13. COMPARISON OF TWO PARTICLE-SIZE SPECTROMETERS FOR AMBIENT AEROSOL MEASUREMENTS. (R827354C002)

    EPA Science Inventory

    There is an ongoing debate on the question which size fraction of particles in ambient air may be responsible for human health effects observed in epidemiological studies. Since there is no single instrument available for the measurement of the particle-size distribution over ...

  14. AMBIENT AMMONIA AND AMMONIUM AEROSOL ACROSS A REGION OF VARIABLE AMMONIA EMISSION DENSITY

    EPA Science Inventory

    The paper presents one year of ambient ammonia (NH3), ammonium (NH4+), hydrochloric acid (HCI), chloride (CI¯), nitric acid (HNO3), nitrate (NO3¯), nitrous acid (HONO), sulfur dioxide (SO2), and sulfate (SO4

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  16. The Effect of Aerosol Hygroscopicity and Volatility on Aerosol Optical Properties During Southern Oxidant and Aerosol Study

    NASA Astrophysics Data System (ADS)

    Khlystov, A.; Grieshop, A. P.; Saha, P.; Subramanian, R.

    2014-12-01

    Secondary organic aerosol (SOA) from biogenic sources can influence optical properties of ambient aerosol by altering its hygroscopicity and contributing to light absorption directly via formation of brown carbon and indirectly by enhancing light absorption by black carbon ("lensing effect"). The magnitude of these effects remains highly uncertain. A set of state-of-the-art instruments was deployed at the SEARCH site near Centerville, AL during the Southern Oxidant and Aerosol Study (SOAS) campaign in summer 2013 to measure the effect of relative humidity and temperature on aerosol size distribution, composition and optical properties. Light scattering and absorption by temperature- and humidity-conditioned aerosols was measured using three photo-acoustic extinctiometers (PAX) at three wavelengths (405 nm, 532 nm, and 870 nm). The sample-conditioning system provided measurements at ambient RH, 10%RH ("dry"), 85%RH ("wet"), and 200 C ("TD"). In parallel to these measurements, a long residence time temperature-stepping thermodenuder (TD) and a variable residence time constant temperature TD in combination with three SMPS systems and an Aerosol Chemical Speciation Monitor (ACSM) were used to assess aerosol volatility and kinetics of aerosol evaporation. We will present results of the on-going analysis of the collected data set. We will show that both temperature and relative humidity have a strong effect on aerosol optical properties. SOA appears to increase aerosol light absorption by about 10%. TD measurements suggest that aerosol equilibrated fairly quickly, within 2 s. Evaporation varied substantially with ambient aerosol loading and composition and meteorology.

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

    SciTech Connect

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

    2009-03-01

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

  18. PIXE analysis of atmospheric aerosols collected over Hungary and Japan

    NASA Astrophysics Data System (ADS)

    Katoh, T.; Amemiya, S.; Tsurita, Y.; Masuda, T.; Koltay, E.; Borbély-Kiss, I.

    1993-04-01

    The PIXE analysis of atmospheric samples collected over Hungary and Japan has been made to investigate characteristic features of the samples of Hungary and Japan, and to compare them. Samples were collected at Budapest, Debrecen, Szerencs, Pálháza in Hungary, and at Tokyo, Noma coast Aichi, Obara-mura Aichi (rural district), Mt. Rokko, in Japan. The PIXE analysis of the samples was made using a 2 MeV proton beam from a Van de Graaff accelerator at Nagoya University. Differences, specially in the concentration of lead, between samples collected in Hungary and Japan were observed.

  19. Inorganic ions in ambient fine particles over a National Park in central India: Seasonality, dependencies between SO42-, NO3-, and NH4+, and neutralization of aerosol acidity

    NASA Astrophysics Data System (ADS)

    Kumar, Samresh; Sunder Raman, Ramya

    2016-10-01

    Twelve hour integrated ambient fine particles (PM2.5) were collected over an Van Vihar National Park (VVNP), in Bhopal, Central India. Samples were collected on filter substrates every-other-day for two years (2012 and 2013). In addition to PM2.5 mass concentration, water soluble inorganic ions (WSIIs) were also measured. Further, on-site meteorological parameters including temperature, wind speed, wind direction, relative humidity, rainfall and atmospheric pressure were recorded. During 2012, the average PM2.5 concentration was 40 ± 31 μgm-3 while during 2013 it was 48 ± 50 μgm-3. Further, in about 20% of the samples the 12 h integrated fine PM mass exceeded the daily (24 h) average standards (60 μgm-3). This observation suggests that the PM2.5 mass concentration at the study site is likely to be in violation of the National Ambient Air Quality Standard (NAAQS), India. During the study period the sum of three major ions (SO42-, NO3-, and NH4+) accounted for 19.4% of PM2.5 mass on average. Air parcel back trajectory ensembles revealed that emissions from thermal power plants were likely to be the main regional source of particulate SO42- and NO3- measured over VVNP. Further, local traffic activities appeared to have no significant impact on the concentrations of PM2.5 and its WSIIs constituents, as revealed by a day-of-the-week analysis. PM2.5 mass, SO42-, NO3-, and NH4+ showed a pronounced seasonal trend with winter (Jan, Feb) and post-monsoon (Oct, Nov, Dec) highs and pre-monsoon (Mar, Apr, May) and monsoon (Jun, Jul, Aug, Sep) lows, during both 2012 and 2013. Further, when the sum of SO42- and NO3- constituted greater than 90% of water soluble inorganic anions by mass, they were linearly dependent on one another and moderately anti-correlated (r2 = 0.60). The molar ratios of NH4+ and non-sea salt SO42- were examined to understand the aerosol neutralization mechanisms and particulate NO3- formation. An assessment of these ratios and subsequent analyses

  20. Spectroscopic characteristics and organic carbon contents in the aerosols collected in Okinawa, Japan

    NASA Astrophysics Data System (ADS)

    Potter, H. J.; Kasaba, T.

    2015-12-01

    Organics in the atmospheric aerosols occupy 20 to 70% of the total mass. Since the proportion of organics is so large that it's important to understand their detailed characteristics. Polymeric compounds called HUmic-Like Substance (HULIS) are known to be present in the atmospheric aerosols. Biomass burning can be a source of HULIS. In this study, atmospheric aerosols were collected at Cape Hedo, a northern tip of Okinawa Island, and we characterized overall features of the organics collected in different seasons. In Okinawa, continental air mass prevails in spring, fall and winter, while maritime air mass from Pacific Ocean prevails in summer. Thus, it is relatively straightforward to identify sources of organics in different seasons. We measured total organic carbon (TOC) and water soluble organic carbon (WSOC) concentrations, and absorbance and fluorescence intensity for the aerosol samples collected during Nov 2012 and July 2014 (n=90). As a result, TOC and WSOC showed almost the same trend, higher concentrations when continental air mass prevailed in fall and winter, while lower concentrations in summer. Percentages of WSOC in TOC accounted for 33-44%. Absorption efficiency, absorbance per 1 ppm organic carbon concentration, of the samples showed higher values in winter and fall, and lower values in summer. Fluorescence efficiency, normalized fluorescence with quinine sulfate per 1 ppm organic carbon concentration, were also different, it is likely that different types of organics were present in the aerosols from different seasons. We are also planning to measure HULIS in the aerosols and will be discussed a link between their contribution and trans-boundary air pollution in Asia.

  1. THERMOPHORESIS AND ITS THERMAL PARAMETERS FOR AEROSOL COLLECTION

    SciTech Connect

    Huang, Z.; Apte, M.; Gundel, L.

    2007-01-01

    The particle collection effi ciency of a prototype environmental tobacco smoke (ETS) sampler based on the use of thermophoresis is determined by optimizing the operational voltage that determines its thermal gradient. This sampler’s heating element was made of three sets of thermophoretic (TP) wires 25μm in diameter suspended across a channel cut in a printed circuit board and mounted with collection surfaces on both sides. The separation between the heating element and the room temperature collection surface was determined in a numerical simulation based on the Brock-Talbot model. Other thermal parameters of this TP ETS sampler were predicted by the Brock-Talbot model for TP deposition. From the normalized results the optimal collection ratio was expressed in terms of operational voltage and fi lter mass. Prior to the Brock-Talbot model simulation for this sampler, 1.0V was used arbitrarily. The operational voltage was raised to 3.0V, and the collection effi ciency was increased by a factor of fi ve for both theory and experiment.

  2. Thermophoresis and Its Thermal Parameters for Aerosol Collection

    SciTech Connect

    Huang, Z.; Apte, Michael; Gundel, Lara

    2007-08-01

    The particle collection efficiency of a prototype environmental tobacco smoke (ETS) sampler based on the use of thermophoresis is determined by optimizing the operational voltage that determines its thermal gradient. This sampler's heating element was made of three sets of thermophoretic (TP) wires 25mu m in diameter suspended across a channel cut in a printed circuit board and mounted with collection surfaces on both sides. The separation between the heating element and the room temperature collection surface was determined in a numerical simulation based on the Brock-Talbot model. Other thermal parameters of this TP ETS sampler were predicted by the Brock-Talbot model for TP deposition. From the normalized results the optimal collection ratio was expressed in terms of operational voltage and fi lter mass. Prior to the Brock-Talbot model simulation for this sampler, 1.0V was used arbitrarily. The operational voltage was raised to 3.0V, and the collection effi ciency was increased by a factor of fi ve for both theory and experiment.

  3. Water-soluble material on aerosols collected within volcanic eruption clouds ( Fuego, Pacaya, Santiaguito, Guatamala).

    USGS Publications Warehouse

    Smith, D.B.; Zielinski, R.A.; Rose, W.I.; Huebert, B.J.

    1982-01-01

    In Feb. and March of 1978, filter samplers mounted on an aircraft were used to collect the aerosol fraction of the eruption clouds from three active Guatemalan volcanoes (Fuego, Pacaya, and Santiaguito). The elements dissolved in the aqueous extracts represent components of water-soluble material either formed directly in the eruption cloud or derived from interaction of ash particles and aerosol components of the plume. Calculations of enrichment factors, based upon concentration ratios, showed the elements most enriched in the extracts relative to bulk ash composition were Cd, Cu, V, F, Cl, Zn, and Pb.-from Authors

  4. Evaporation Kinetics and Phase of Laboratory and Ambient Secondary Organic Aerosol

    SciTech Connect

    Vaden, Timothy D.; Imre, Dan G.; Beranek, Josef; Shrivastava, ManishKumar B.; Zelenyuk, Alla

    2011-02-08

    Field measurements of secondary organic aerosol (SOA) find higher mass loads than predicted by models, sparking intense efforts to find additional SOA sources but leaving the assumption of rapid SOA evaporation unchallenged. We characterized room-temperature evaporation of pure SOA and SOA formed in the presence of spectator organic vapors with and without aging. We find that it takes ~24 hrs for pure SOA particles to evaporate 75% of their mass, which is in sharp contrast to the ~10 minutes timescales predicted by models. The presence of spectator organic vapors and aging dramatically reduces the evaporation, and in some cases nearly stops it. For all cases, SOA evaporation behavior is size independent and does not follow the liquid droplet evaporation kinetics assumed by models.

  5. Ambient aerosol chlorine concentrations and artefacts during the MEGAPOLI Paris campaigns

    NASA Astrophysics Data System (ADS)

    Furger, Markus; Visser, Suzanne; Slowik, Jay; Crippa, Monica; Poulain, Laurent; Sciare, Jean; Flechsig, Uwe; Prévôt, André; Baltensperger, Urs

    2015-04-01

    Trace elements, especially those that are toxic, can affect the environment in significant ways. Studying them is advantageous with respect to a refinement of source apportionment when measured with high time resolution and appropriate size segregation. This approach is especially useful in urban environments with numerous time-variant emission sources distributed across a relatively narrow space. Two field campaigns took place in the framework of the MEGAPOLI project in Paris, France: one in the summer of 2009 (1-31 July), the other in the winter of 2010 (11 Jan - 10 Feb). Rotating drum impactors (RDI) were operated at an urban and a suburban site in each campaign. The RDI segregated the aerosols into three size ranges (PM10-2.5, PM2.5-1.0 and PM1.0-0.3) and sampled with 2-hour time resolution. The samples were analyzed with synchrotron radiation-induced X-ray fluorescence spectrometry (SR-XRF) at the synchrotron facility of the Paul Scherrer Institute (SLS), where a broad range of elements (Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn) was analyzed for each size range. Time series of the analyzed elements for the different sites and campaigns were prepared to characterize the aerosol trace element composition and temporal behavior for different weather situations and urban environments. Quality assurance was performed partly by intercomparison with independent measurements. An exceptional behavior was observed for chlorine (Cl), where periods with zero RDI concentration alternated with periods of normal load. Zero concentrations were not observed in particle-into-liquid (PILS) measurements. This identifies the observed behavior as a RDI sampling artefact. Nevertheless, the non-zero periods of Cl concentrations are still a gain in information compared to conventional sampling techniques, mainly due to the high time resolution.

  6. Note: A combined aerodynamic lens/ambient pressure x-ray photoelectron spectroscopy experiment for the on-stream investigation of aerosol surfaces

    SciTech Connect

    Mysak, Erin R.; Starr, David E.; Wilson, Kevin R.; Bluhm, Hendrik

    2010-01-15

    We discuss a new approach for the measurement of the surfaces of free aerosol particles with diameters from 50 to 1000 nm. Particles in this size range have significant influence on the heterogeneous chemistry in the atmosphere and affect human health. Interfacing an aerodynamic lens to an ambient pressure x-ray photoelectron spectrometer permits measurement of the surface chemical composition of unsupported aerosol particles in real time. We discuss the basic considerations for the design of such an instrument, its current limitations and potentials for improvement. Results from a proof-of-principle experiment on silicon oxide particles with average diameters of 270 nm are shown.

  7. Molecular characterization of free tropospheric aerosol collected at the Pico Mountain Observatory: a case study with long range transported biomass burning plumes

    NASA Astrophysics Data System (ADS)

    Dzepina, K.; Mazzoleni, C.; Fialho, P.; China, S.; Zhang, B.; Owen, R. C.; Helmig, D.; Hueber, J.; Kumar, S.; Perlinger, J. A.; Kramer, L.; Dziobak, M. P.; Ampadu, M. T.; Olsen, S.; Wuebbles, D. J.; Mazzoleni, L. R.

    2014-09-01

    Free tropospheric aerosol was sampled at the Pico Mountain Observatory located at 2225 m a.m.s.l. on Pico Island of the Azores archipelago in the North Atlantic. The observatory (38°28'15'' N; 28°24'14'' W) is located ∼3900 km east and downwind of North America, which enables studies of free tropospheric air transported over long distances, mainly from North America. Aerosol samples collected on filters from June to October 2012 were analyzed to characterize organic carbon, elemental carbon and inorganic ion species. The average ambient concentration of aerosol was 0.9 μg m-3; on average organic aerosol contributes the majority of mass (57%), followed by sulfate (21%) and nitrate (17%). Filter-collected aerosol measurements were positively correlated (with an r2 ≥ 0.80) with continuous aerosol measurements of black carbon, aerosol light scattering and number concentration. Water-soluble organic carbon (WSOC) species extracted from two aerosol samples (9/24 and 9/25) collected consecutively during a pollution event were analyzed using ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry. FLEXPART retroplume analysis shows the sampled air masses were very aged (average plume age > 12 days). Approximately 4000 molecular formulas were assigned to each of the mass spectra in the range of m/z 100-1000. The majority of the assigned molecular formulas have unsaturated structures with CHO and CHNO elemental compositions. These aged WSOC compounds have an average O / C ratio of ∼0.45, which is relatively low compared to O / C ratios of other aged aerosol and might be the result of evaporation and increased fragmentation during long-range transport. The increase in aerosol loading during the measurement period of 9/24 was linked to biomass burning emissions from North America by FLEXPART retroplume analysis and Moderate Resolution Imaging Spectroradiometer (MODIS) fire counts. This was confirmed with biomass burning markers detected in

  8. Heterogeneous reaction of peroxyacetic acid and hydrogen peroxide on ambient aerosol particles under dry and humid conditions: kinetics, mechanism and implications

    NASA Astrophysics Data System (ADS)

    Wu, Q. Q.; Huang, L. B.; Liang, H.; Zhao, Y.; Huang, D.; Chen, Z. M.

    2015-02-01

    Hydrogen peroxide (H2O2) and organic peroxides play important roles in the cycle of oxidants and the formation of secondary aerosols in the atmosphere. Recent field observations suggest that peroxyacetic acid (PAA, CH3C(O)OOH) is one of the most important organic peroxides in the atmosphere, whose budget is potentially related to the aerosols. Here we present the first laboratory measurements of the uptake coefficient of gaseous PAA and H2O2 onto the ambient fine particulate matter (PM2.5) as a function of relative humidity (RH) at 298 K. The results show that the PM2.5, which was collected in an urban area, can take up PAA and H2O2 at the uptake coefficient (γ) of 10-4, and both γPAA and γH2O2 increase with increasing RH. However, γPAA is more sensitive to the RH variation than is γH2O2, which indicates that the enhanced uptake of peroxide compounds on PM2.5 under humid conditions is dominated by chemical processes rather than dissolution. Considering that mineral dust is one of the main components of PM2.5, we also determined the uptake coefficients of gaseous PAA and H2O2 on authentic Asian Dust Storm (ADS) and Arizona Test Dust (ATD) particles. Compared to ambient PM2.5, ADS shows a similar γ value and RH dependence in its uptake coefficient for PAA and H2O2, while ATD gives a negative dependence on RH. The present study indicates that in addition to the mineral dust in PM2.5, other components (e.g., inorganic soluble salts) are also important to the uptake of peroxide compounds. When the heterogeneous reaction of PAA on PM2.5 is considered, its atmospheric lifetime is estimated to be 3.3 h on haze days and 7.6 h on non-haze days, values which agree well with the field observed result.

  9. Mass loading of size-segregated atmospheric aerosols in the ambient air during fireworks episodes in eastern Central India.

    PubMed

    Nirmalkar, Jayant; Deb, Manas K; Deshmukh, Dhananjay K; Verma, Santosh K

    2013-04-01

    The effects of combustion of the fire crackers on the air quality in eastern Central India were studied for the first time during Diwali festival. This case study analyzes the size distribution and temporal variation of aerosols collected in the rural area of eastern Central India during pre-diwali, Diwali and post-diwali period for the year of 2011. Fifteen aerosol samples were collected during the special case study of Diwali period using Andersen sampler. The mean concentrations of PM10 (respirable particulate matter) were found to be 212.8 ± 4.2, 555.5 ± 20.2 and 284.4 ± 5.8 during pre-diwali, Diwali and post-diwali period, respectively. During Diwali festival PM10 concentration was about 2.6 and 1.9 times higher than pre-diwali and post-diwali period, respectively. PM2.5 (fine) and PM1 (submicron) concentrations during Diwali festival were more than 2 times higher than pre-diwali and post-diwali.

  10. 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

  11. Verification of traffic emitted aerosol components in the ambient air of Cologne (Germany)

    NASA Astrophysics Data System (ADS)

    Weckwerth, Gerd

    Emission of heavy metals, besides ozone and diesel-soot, is one of the most significant environmental problems caused by the existing transport systems. Emission arises from different parts of vehicles (tyres, brakes, exhausts) or running trains (rails, wheels, overhead cables, etc.). Various types of emission with their insufficiently known ways of spreading makes it difficult to estimate the risk and to realise effective counter-measures. Size-dependent sampling of aerosols with the virtual impactor technique of a dichotomous sampler (<2.5 μm, 2.5-10 μm) allows one to identify several aerosol components at the sampling locations and to reliably determine their relative proportions. Analyses of 30-40 elements from immission samplings at 12 places in and around Cologne are compared with specific patterns of elements from relevant emission sources. Moreover, taking into account the particle size, relative abundances of Zn, Mo, Cu and Sb can be estimated by assuming an average of around 30% of diesel-soot in the fine fraction, and ˜3% from an abraded tyre material together with ˜0.3% from rubbed off brake-linings in the coarse fraction. The assumption of 0.3% for brake-linings is based on the relative abundances of Cu and Sb which besides Cd are the most highly enriched. Since most brake-linings used in cars contain these elements in an unusually high quantity (5-20% Cu and 1-5% Sb) and are in very similar ratios as measured in the coarse fraction, Cu and Sb may be taken as quantitative tracers for the brake-lining component in the immission. The environmental interest in Sb arises mainly from the toxicological potential of the compounds Sb 2S 3 and Sb 2O 3. Other traffic related components could only be identified very close to the sources of emissions. Besides Pt from cars with catalysators and Cu emitted from overhead cables of trams, an As-enrichment from rusting rails, which segregates into fine particles because of shaking due to passing trains, was

  12. Ambient temperature and the occurrence of collective violence: a new analysis.

    PubMed

    Carlsmith, J M; Anderson, C A

    1979-03-01

    Prevalent folklore suggests that riots tend to occur during periods of very hot weather. Baron and Ransberger examined 102 major riots in the United States between 1967 and 1971 and concluded that the frequency of collective violence and ambient temperature are curvilinearly related. The present article points out that the Baron and Ransberger analysis did not take account of the different number of days in different temperature ranges. The artifact is eliminated, and the probability of a riot, conditional upon temperature, is estimated. When this is done, the evidence strongly suggests that the conditional probability of a riot increases monotonically with temperature. Some general implications of such data analyses are discussed.

  13. Nonpolar organic compounds in fine particles: quantification by thermal desorption-GC/MS and evidence for their significant oxidation in ambient aerosols in Hong Kong.

    PubMed

    Yu, Jian Zhen; Huang, X H Hilda; Ho, Steven S H; Bian, Qijing

    2011-12-01

    Nonpolar organic compounds (NPOCs) in ambient particulate matter (PM) commonly include n-alkanes, branched alkanes, hopanes and steranes, and polycyclic aromatic hydrocarbons (PAHs). The recent development of thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS) has greatly reduced time and labor in their quantification by eliminating the laborious solvent extraction and sample concentration steps in the traditional approach that relies on solvent extraction. The simplicity of the TD-GCMS methods has afforded us concentration data of NPOCs in more than 90 aerosol samples in two aerosol field studies and 20 vehicular emissions-dominated source samples in Hong Kong over the past few years. In this work, we examine the interspecies relationships between select NPOCs and their concentration ratios to elemental carbon (EC) among the ambient samples and among the source samples. Our analysis indicates that hopanes were mainly from vehicular emissions and they were significantly oxidized in ambient PM. The hopane/EC ratio in ambient samples was on average less than half of the ratio in vehicular emissions-dominated source samples. This highlights the necessity in considering oxidation loss in applying organic tracer data in source apportionment studies. Select PAH/EC ratio-ratio plots reveal that PAHs had diverse sources and vehicular emissions were unlikely a dominant source for PAHs in Hong Kong. Biomass burning and other regional sources likely dominated ambient PAHs in Hong Kong. PMID:21983947

  14. Molecular characterization of free tropospheric aerosol collected at the Pico Mountain Observatory: a case study with a long-range transported biomass burning plume

    NASA Astrophysics Data System (ADS)

    Dzepina, K.; Mazzoleni, C.; Fialho, P.; China, S.; Zhang, B.; Owen, R. C.; Helmig, D.; Hueber, J.; Kumar, S.; Perlinger, J. A.; Kramer, L. J.; Dziobak, M. P.; Ampadu, M. T.; Olsen, S.; Wuebbles, D. J.; Mazzoleni, L. R.

    2015-05-01

    Free tropospheric aerosol was sampled at the Pico Mountain Observatory located at 2225 m above mean sea level on Pico Island of the Azores archipelago in the North Atlantic. The observatory is located ~ 3900 km east and downwind of North America, which enables studies of free tropospheric air transported over long distances. Aerosol samples collected on filters from June to October 2012 were analyzed to characterize organic carbon, elemental carbon, and inorganic ions. The average ambient concentration of aerosol was 0.9 ± 0.7 μg m-3. On average, organic aerosol components represent the largest mass fraction of the total measured aerosol (60 ± 51%), followed by sulfate (23 ± 28%), nitrate (13 ± 10%), chloride (2 ± 3%), and elemental carbon (2 ± 2%). Water-soluble organic matter (WSOM) extracted from two aerosol samples (9/24 and 9/25) collected consecutively during a pollution event were analyzed using ultrahigh-resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. Approximately 4000 molecular formulas were assigned to each of the mass spectra in the range of m/z 100-1000. The majority of the assigned molecular formulas had unsaturated structures with CHO and CHNO elemental compositions. FLEXPART retroplume analyses showed the sampled air masses were very aged (average plume age > 12 days). These aged aerosol WSOM compounds had an average O/C ratio of ~ 0.45, which is relatively low compared to O/C ratios of other aged aerosol. The increase in aerosol loading during the measurement period of 9/24 was linked to biomass burning emissions from North America by FLEXPART retroplume analysis and Moderate Resolution Imaging Spectroradiometer (MODIS) fire counts. This was confirmed with biomass burning markers detected in the WSOM and with the morphology and mixing state of particles as determined by scanning electron microscopy. The presence of markers characteristic of aqueous-phase reactions of phenolic species suggests

  15. Ability of device to collect bacteria from cough aerosols generated by adults with cystic fibrosis

    PubMed Central

    Ku, David N.; Ku, Sarah K.; Helfman, Beth; McCarty, Nael A.; Wolff, Bernard J.; Winchell, Jonas M.; Anderson, Larry J.

    2016-01-01

    Background: Identifying lung pathogens and acute spikes in lung counts remain a challenge in the treatment of patients with cystic fibrosis (CF). Bacteria from the deep lung may be sampled from aerosols produced during coughing. Methods: A new device was used to collect and measure bacteria levels from cough aerosols of patients with CF. Sputum and oral specimens were also collected and measured for comparison. Pseudomonas aeruginosa, Staphylococcus aureus, Klebsiella pneumoniae, and Streptococcus mitis were detected in specimens using Real-Time Polymerase Chain Reaction (RT-PCR) molecular assays. Results: Twenty adult patients with CF and 10 healthy controls participated. CF related bacteria (CFRB) were detected in 13/20 (65%) cough specimens versus 15/15 (100%) sputum specimens. Commensal S. mitis was present in 0/17 (0%, p=0.0002) cough specimens and 13/14 (93%) sputum samples. In normal controls, no bacteria were collected in cough specimens but 4/10 (40%) oral specimens were positive for CFRB. Conclusions: Non-invasive cough aerosol collection may detect lower respiratory pathogens in CF patients, with similar specificity and sensitivity to rates detected by BAL, without contamination by oral CFRB or commensal bacteria. PMID:27781088

  16. Effect of biomass burning over the western North Pacific Rim: wintertime maxima of anhydrosugars in ambient aerosols from Okinawa

    NASA Astrophysics Data System (ADS)

    Zhu, C.; Kawamura, K.

    2014-10-01

    Biomass burning (BB) largely modifies the chemical compositions of atmospheric aerosols on the globe. We collected aerosol samples (TSP) at Cape Hedo, subtropical Okinawa Island from October 2009 to February 2012 to study anhydrosugars as BB tracers. Levoglucosan was detected as the dominant anhydrosugar followed by its isomers, mannosan and galactosan. We found a clear seasonal trend of levoglucosan and mannosan with winter maxima and summer minima. Positive correlation was found between levoglucosan and nss-K+ (r = 0.38, p < 0.001); the latter is another BB tracer. The analyses of air mass trajectories and fire spots demonstrated that the seasonal variations of anhydrsosugsars are caused by a long-range transport of BB emissions from the Asian continent. We found winter maxima of anhydrosugars, which may be associated with open burning and domestic heating and cooking in north and northeast China, Mongolia and Russia and with the enhanced westerly. The monthly averaged levoglucosan/mannosan ratios were lower (2.1-4.8) in May-June and higher (13.3-13.9) in November-December. The lower values may be associated with softwood burning in north China, Korea and southwest Japan whereas the higher values are probably caused by agriculture waste burning of maize straw in the North China Plain. Anhydrosugars comprised 0.22% of water-soluble organic carbon (WSOC) and 0.13% of organic carbon (OC). The highest values to WSOC (0.37%) and OC (0.25%) were found in winter, again indicating an important BB contribution to Okinawa aerosols in winter. This study provides useful information to better understand the effect of East Asian biomass burning on the air quality in the western North Pacific Rim.

  17. Effect of biomass burning over the western North Pacific Rim: wintertime maxima of anhydrosugars in ambient aerosols from Okinawa

    NASA Astrophysics Data System (ADS)

    Zhu, C.; Kawamura, K.; Kunwar, B.

    2015-02-01

    Biomass burning (BB) largely modifies the chemical composition of atmospheric aerosols on the globe. We collected aerosol samples (TSP) at Cape Hedo, on subtropical Okinawa Island, from October 2009 to February 2012 to study anhydrosugars as BB tracers. Levoglucosan was detected as the dominant anhydrosugar followed by its isomers, mannosan and galactosan. We found a clear seasonal trend of levoglucosan and mannosan with winter maxima and summer minima. Positive correlation was found between levoglucosan and nss-K+ (r = 0.38, p < 0.001); the latter is another BB tracer. The analyses of air mass trajectories and fire spots demonstrated that the seasonal variations of anhydrosugars are caused by long-range transport of BB emissions from the Asian continent. We found winter maxima of anhydrosugars, which may be associated with open burning and domestic heating and cooking in northern and northeastern China, Mongolia and Russia and with the enhanced westerly winds. The monthly averaged levoglucosan / mannosan ratios were lower (2.1-4.8) in May-June and higher (13.3-13.9) in November-December. The lower values may be associated with softwood burning in northern China, Korea and southwestern Japan whereas the higher values are probably caused by agricultural waste burning of maize straw in the North China Plain. Anhydrosugars comprised 0.22% of water-soluble organic carbon (WSOC) and 0.13% of organic carbon (OC). The highest values to WSOC (0.37%) and OC (0.25%) were found in winter, again indicating an important BB contribution to Okinawa aerosols in winter. This study provides useful information to better understand the effect of East Asian biomass burning on the air quality in the western North Pacific Rim.

  18. Reconstruction of passive open-path FTIR ambient spectra using meteorological measurements and its application for detection of aerosol cloud drift.

    PubMed

    Kira, Oz; Dubowski, Yael; Linker, Raphael

    2015-07-27

    Remote sensing of atmospheric aerosols is of great importance to public and environmental health. This research promotes a simple way of detecting an aerosol cloud using a passive Open Path FTIR (OP-FTIR) system, without utilizing radiative transfer models and without relying on an artificial light source. Meteorological measurements (temperature, relative humidity and solar irradiance), and chemometric methods (multiple linear regression and artificial neural networks) together with previous cloud-free OP-FTIR measurements were used to estimate the ambient spectrum in real time. The cloud detection process included a statistical comparison between the estimated cloud-free signal and the measured OP-FTIR signal. During the study we were able to successfully detect several aerosol clouds (water spray) in controlled conditions as well as during agricultural pesticide spraying in an orchard.

  19. Ambient spark generation to synthesize carbon-encapsulated metal nanoparticles in continuous aerosol manner

    NASA Astrophysics Data System (ADS)

    Byeon, Jeong Hoon; Park, Jae Hong; Yoon, Ki Young; Hwang, Jungho

    2009-11-01

    We report the use of spark generation in an inert gas atmosphere to synthesize carbon-encapsulated metal nanoparticles (CEMNs) in a continuous aerosol manner using a metal (nickel, cobalt, iron)-graphite carbon electrode configuration without the use of a vacuum. The spark-generated particles consisted of CEMNs and carbonaceous aggregated debris. The outer layer of the CEMNs showed parallel fringes (ordered graphitic nanostructures) while the debris consisted of disordered nanostructures. Electron and X-ray diffraction showed that both metal and graphite in the CEMNs were the pure elements except for iron-carbon, which contained a carbide phase. Based on the order of the activation energies for carbon diffusion into a metal: iron-carbon (10.5-16.5 kcal mol-1) < cobalt-carbon (34.7 kcal mol-1) ~ nickel-carbon (33.0-34.8 kcal mol-1), it was concluded that carbide particles form more easily from elemental iron than nickel or cobalt. The metal-to-carbon mass fractions of the spark-generated particles from nickel (anode)-carbon (cathode), cobalt-carbon, and iron-carbon spark configurations were 18.7, 28.3, and 11.2%, respectively, while the mass fractions for the configurations of metal (cathode)-carbon (anode) were 6.4, 9.1, and 4.3%, respectively. Similarly, the yield of CEMNs from the metal (anode)-carbon (cathode) electrodes was higher (54, 61, and 53%) than that of metal (cathode)-carbon (anode) electrodes (18, 30, and 18%).

  20. A novel rocket-based in-situ collection technique for mesospheric and stratospheric aerosol particles

    NASA Astrophysics Data System (ADS)

    Reid, W.; Achtert, P.; Ivchenko, N.; Magnusson, P.; Kuremyr, T.; Shepenkov, V.; Tibert, G.

    2012-11-01

    A technique for collecting aerosol particles between altitudes of 85 and 17 km is described. Collection probes are ejected from a sounding rocket allowing for multi-point measurements. Each probe is equipped with 110 collection samples that are 3 mm in diameter. The collection samples are one of three types: standard transmission electron microscopy carbon grids, glass fibre filter paper or silicone gel. Each collection sample is exposed over a 50 m to 5 km height range with a total of 45 separate ranges. Post-flight electron microscopy gives size-resolved information on particle number, shape and elemental composition. Each collection probe is equipped with a suite of sensors to capture the probe's status during the fall. Parachute recovery systems along with GPS-based localization ensure that each probe can be located and recovered for post-flight analysis.

  1. A robust ambient temperature collection and stabilization strategy: Enabling worldwide functional studies of the human microbiome.

    PubMed

    Anderson, Ericka L; Li, Weizhong; Klitgord, Niels; Highlander, Sarah K; Dayrit, Mark; Seguritan, Victor; Yooseph, Shibu; Biggs, William; Venter, J Craig; Nelson, Karen E; Jones, Marcus B

    2016-01-01

    As reports on possible associations between microbes and the host increase in number, more meaningful interpretations of this information require an ability to compare data sets across studies. This is dependent upon standardization of workflows to ensure comparability both within and between studies. Here we propose the standard use of an alternate collection and stabilization method that would facilitate such comparisons. The DNA Genotek OMNIgene∙Gut Stool Microbiome Kit was compared to the currently accepted community standard of freezing to store human stool samples prior to whole genome sequencing (WGS) for microbiome studies. This stabilization and collection device allows for ambient temperature storage, automation, and ease of shipping/transfer of samples. The device permitted the same data reproducibility as with frozen samples, and yielded higher recovery of nucleic acids. Collection and stabilization of stool microbiome samples with the DNA Genotek collection device, combined with our extraction and WGS, provides a robust, reproducible workflow that enables standardized global collection, storage, and analysis of stool for microbiome studies. PMID:27558918

  2. A robust ambient temperature collection and stabilization strategy: Enabling worldwide functional studies of the human microbiome

    PubMed Central

    Anderson, Ericka L.; Li, Weizhong; Klitgord, Niels; Highlander, Sarah K.; Dayrit, Mark; Seguritan, Victor; Yooseph, Shibu; Biggs, William; Venter, J. Craig; Nelson, Karen E.; Jones, Marcus B.

    2016-01-01

    As reports on possible associations between microbes and the host increase in number, more meaningful interpretations of this information require an ability to compare data sets across studies. This is dependent upon standardization of workflows to ensure comparability both within and between studies. Here we propose the standard use of an alternate collection and stabilization method that would facilitate such comparisons. The DNA Genotek OMNIgene∙Gut Stool Microbiome Kit was compared to the currently accepted community standard of freezing to store human stool samples prior to whole genome sequencing (WGS) for microbiome studies. This stabilization and collection device allows for ambient temperature storage, automation, and ease of shipping/transfer of samples. The device permitted the same data reproducibility as with frozen samples, and yielded higher recovery of nucleic acids. Collection and stabilization of stool microbiome samples with the DNA Genotek collection device, combined with our extraction and WGS, provides a robust, reproducible workflow that enables standardized global collection, storage, and analysis of stool for microbiome studies. PMID:27558918

  3. A new direct thermal desorption-GC/MS method: Organic speciation of ambient particulate matter collected in Golden, BC

    NASA Astrophysics Data System (ADS)

    Ding, Luyi C.; Ke, Fu; Wang, Daniel K. W.; Dann, Tom; Austin, Claire C.

    Particulate matter having an aerodynamic diameter less than 2.5 μm (PM2.5) is thought to be implicated in a number of medical conditions, including cancer, rheumatoid arthritis, heart attack, and aging. However, very little chemical speciation data is available for the organic fraction of ambient aerosols. A new direct thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS) method was developed for the analysis of the organic fraction of PM2.5. Samples were collected in Golden, British Columbia, over a 15-month period. n-Alkanes constituted 33-98% by mass of the organic compounds identified. PAHs accounted for 1-65% and biomarkers (hopanes and steranes) 1-8% of the organic mass. Annual mean concentrations were: n-alkanes (0.07-1.55 ng m -3), 16 PAHs (0.02-1.83 ng m -3), and biomarkers (0.02-0.18 ng m -3). Daily levels of these organics were 4.89-74.38 ng m -3, 0.27-100.24 ng m -3, 0.14-4.39 ng m -3, respectively. Ratios of organic carbon to elemental carbon (OC/EC) and trends over time were similar to those observed for PM2.5. There was no clear seasonal variation in the distribution of petroleum biomarkers, but elevated levels of other organic species were observed during the winter. Strong correlations between PAHs and EC, and between petroleum biomarkers and EC, suggest a common emission source - most likely motor vehicles and space heating.

  4. Predicting ambient aerosol Thermal Optical Reflectance (TOR) measurements from infrared spectra: organic carbon

    NASA Astrophysics Data System (ADS)

    Dillner, A. M.; Takahama, S.

    2014-11-01

    calibration is linear. Using samples in the calibration set that have a different OM / OC or ammonium / OC distributions than the test set leads to only a modest increase in bias and normalized error in the predicted samples. We conclude that FT-IR analysis with partial least squares regression is a robust method for accurately predicting TOR OC in IMPROVE network samples; providing complementary information to the organic functional group composition and organic aerosol mass estimated previously from the same set of sample spectra (Ruthenburg et al., 2014).

  5. PIXE Analysis of Aerosol and Soil Samples Collected in the Adirondack Mountains

    NASA Astrophysics Data System (ADS)

    Yoskowitz, Joshua; Ali, Salina; Nadareski, Benjamin; Labrake, Scott; Vineyard, Michael

    2014-09-01

    We have performed an elemental analysis of aerosol and soil samples collected at Piseco Lake in Upstate New York using proton induced X-ray emission spectroscopy (PIXE). This work is part of a systematic study of airborne pollution in the Adirondack Mountains. Of particular interest is the sulfur content that can contribute to acid rain, a well-documented problem in the Adirondacks. We used a nine-stage cascade impactor to collect the aerosol samples near Piseco Lake and distribute the particulate matter onto Kapton foils by particle size. The soil samples were also collected at Piseco Lake and pressed into cylindrical pellets for experimentation. PIXE analysis of the aerosol and soil samples were performed with 2.2-MeV proton beams from the 1.1-MV Pelletron accelerator in the Union College Ion-Beam Analysis Laboratory. There are higher concentrations of sulfur at smaller particle sizes (0.25-1 μm), suggesting that it could be suspended in the air for days and originate from sources very far away. Other elements with significant concentrations peak at larger particle sizes (1-4 μm) and are found in the soil samples, suggesting that these elements could originate in the soil. The PIXE analysis will be described and the resulting data will be presented.

  6. Chemical Analysis of Fractionated Halogens in Atmospheric Aerosols Collected in Okinawa, Japan

    NASA Astrophysics Data System (ADS)

    Tsuhako, A.; Miyagi, Y.; Somada, Y.; Azechi, S.; Handa, D.; Oshiro, Y.; Murayama, H.; Arakaki, T.

    2013-12-01

    Halogens (Cl, Br and I) play important roles in the atmosphere, e.g. ozone depletion by Br during spring in Polar Regions. Sources of halogens in atmospheric aerosols are mainly from ocean. But, for example, when we analyzed Br- with ion chromatography, its concentrations were almost always below the detection limit, which is also much lower than the estimated concentrations from sodium ion concentrations. We hypothesized that portions of halogens are escaped to the atmosphere, similar to chlorine loss, changed their chemical forms to such as BrO3- and IO3-, and/or even formed precipitates. There was few reported data so far about fractionated halogen concentrations in atmospheric aerosols. Thus, purpose of this study was to determine halogen concentrations in different fractions; free ion, water-soluble chemically transformed ions and precipitates using the authentic aerosols. Moreover, we analyzed seasonal variation for each fraction. Atmospheric aerosol samples were collected at Cape Hedo Atmosphere and Aerosol Monitoring Station (CHAAMS) of Okinawa, Japan during January 2010 and August 2013. A high volume air sampler was used for collecting total particulate matters on quartz filters on a weekly basis. Ultrapure water was used to extract water-soluble factions of halogens. The extracted solutions were filtered with the membrane filter and used for chemical analysis with ion chromatography and ICP-MS. Moreover, the total halogens in aerosols were obtained after digesting aerosols with tetramethylammonium hydroxide (TMAH) using the microwave and analysis with ICP-MS. For Cl, water-soluble Cl- accounted for about 70% of the estimates with Na content. No other forms of water-soluble Cl were found. About 30% of Cl was assumed volatilized to the gas-phase. For Br, water-soluble Br accounted for about 43% of the estimates with Na content, and within the 43%, about 10% of Br was not in the form of Br-. About 46% of Br was assumed volatilized to the gas-phase. For I

  7. Raman microscopy of size-segregated aerosol particles, collected at the Sonnblick Observatory in Austria

    NASA Astrophysics Data System (ADS)

    Ofner, Johannes; Kasper-Giebl, Anneliese; Kistler, Magdalena; Matzl, Julia; Schauer, Gerhard; Hitzenberger, Regina; Lohninger, Johann; Lendl, Bernhard

    2014-05-01

    Size classified aerosol samples were collected using low pressure impactors in July 2013 at the high alpine background site Sonnnblick. The Sonnblick Observatory is located in the Austrian Alps, at the summit of Sonnblick 3100 m asl. Sampling was performed in parallel on the platform of the Observatory and after the aerosol inlet. The inlet is constructed as a whole air inlet and is operated at an overall sampling flow of 137 lpm and heated to 30 °C. Size cuts of the eight stage low pressure impactors were from 0.1 to 12.8 µm a.d.. Alumina foils were used as sample substrates for the impactor stages. In addition to the size classified aerosol sampling overall aerosol mass (Sharp Monitor 5030, Thermo Scientific) and number concentrations (TSI, CPC 3022a; TCC-3, Klotz) were determined. A Horiba LabRam 800HR Raman microscope was used for vibrational mapping of an area of about 100 µm x 100 µm of the alumina foils at a resolution of about 0.5 µm. The Raman microscope is equipped with a laser with an excitation wavelength of 532 nm and a grating with 300 gr/mm. Both optical images and the related chemical images were combined and a chemometric investigation of the combined images was done using the software package Imagelab (Epina Software Labs). Based on the well-known environment, a basic assignment of Raman signals of single particles is possible at a sufficient certainty. Main aerosol constituents e.g. like sulfates, black carbon and mineral particles could be identified. First results of the chemical imaging of size-segregated aerosol, collected at the Sonnblick Observatory, will be discussed with respect to standardized long-term measurements at the sampling station. Further, advantages and disadvantages of chemical imaging with subsequent chemometric investigation of the single images will be discussed and compared to the established methods of aerosol analysis. The chemometric analysis of the dataset is focused on mixing and variation of single compounds at

  8. A new method of satellite-based haze aerosol monitoring over the North China Plain and a comparison with MODIS Collection 6 aerosol products

    NASA Astrophysics Data System (ADS)

    Yan, Xing; Shi, Wenzhong; Luo, Nana; Zhao, Wenji

    2016-05-01

    With worldwide urbanization, hazy weather has been increasingly frequent, especially in the North China Plain. However, haze aerosol monitoring remains a challenge. In this paper, MODerate resolution Imaging Spectroradiometer (MODIS) measurements were used to develop an enhanced haze aerosol retrieval algorithm (EHARA). This method can work not only on hazy days but also on normal weather days. Based on 12-year (2002-2014) Aerosol Robotic Network (AERONET) aerosol property data, empirical single scattering albedo (SSA) and asymmetry factor (AF) values were chosen to assist haze aerosol retrieval. For validation, EHARA aerosol optical thickness (AOT) values, along with MODIS Collection 6 (C6) dark-pixel and deep blue aerosol products, were compared with AERONET data. The results show that the EHARA can achieve greater AOT spatial coverage under hazy conditions with a high accuracy (73% within error range) and work a higher resolution (1-km). Additionally, this paper presents a comprehensive discussion of the differences between and limitations of the EHARA and the MODIS C6 DT land algorithms.

  9. Long-Range Transport of Perchlorate Observed in the Atmospheric Aerosols Collected at Okinawa Island, Japan

    NASA Astrophysics Data System (ADS)

    Handa, D.; Okada, K.; Kuroki, Y.; Nakama, Y.; Nakajima, H.; Arakaki, T.; Tanahara, A.; Oomori, T.; Miyagi, T.; Kadena, H.; Ishizaki, T.; Nakama, F.

    2007-12-01

    The study of perchlorate has become quite active in the U.S. in the last several years. Perchlorate has been recognized as a new environmental pollutant and it attracted much attention quickly in the world. The health concern about perchlorate stems from the fact that it displaces iodide in the thyroid gland, while iodine-containing thyroid hormones are essential for proper neural development from the fetal stage through the first years of life. In this study, we determined the concentrations of perchlorate ion present in the atmospheric aerosols collected in Okinawa Island, Japan. We then examined the relationships between the perchlorate concentrations and the environmental parameters and the climatic conditions peculiar to Okinawa. Bulk aerosol samples were collected on quartz filters by using a high volume air sampler at Cape Hedo Atmosphere and Aerosol Monitoring Station (CHAAMS). Each sampling duration was one week. The quartz filters with aerosols were stirred with Milli-Q pure water for three hours before perchlorate ion was extracted. The extracted perchlorate ion concentrations were determined by ion chromatography (ICS-2000, DIONEX). The mean perchlorate concentration for the samples collected at CHAAMS was 1.83 ng/m3, and the minimum was 0.18 ng/m3. The samples collected during November 21-27, 2005, January 23-30, 2006 and April 24-01, 2006 had highest perchlorate concentrations. For these three samples, we performed back trajectory analysis, and found that the air mass for the three samples arrived from the Asian continent. A relatively strong correlation (r2 = 0.55) was found between perchlorate and nss-sulfate concentrations for the CHAAMS samples. Furthermore, we analyzed perchlorate in the soils and the fertilizers used for sugar cane farming around the CHAAMS area. The Milli-Q extract of the soil and the fertilizers did not contain any detectable levels of perchlorate ions. Therefore, it was suggested that perchlorate found in the atmospheric

  10. Bipolar charged aerosol agglomeration and collection by a two-zone agglomerator.

    PubMed

    Xiang, X D; Chen, B Z; Colbeck, I

    2001-07-01

    In older to collect fine particles more efficiently, a new-type electrostatic agglomerator with two zones was developed. The distinguishing feature of this electrostatic agglomerator is that the particles are bipolarly charged and coagulated in the same alternating electric field simultaneously. The silica flour with 2 microns mass median diameter and the smoke from burning wood powder were used as test aerosol. The comparison experimental results have shown that when the mean electric field is 4 kV/cm the collection efficiency of the new electrostatic agglomerator was 98.2% for silica flour and 67.4% for wood powder smoke. Under the same experimental condition, the collection efficiency of the electrostatic agglomerator with three zones was 97.4% for collecting silica flour and the collection efficiency of the electrostatic precipitator was 56.3% for wood powder smoke.

  11. Trace element pass-through for cellulose filters when used for aerosol collection

    NASA Astrophysics Data System (ADS)

    Dolske, Donald A.; Schneider, J.; Sievering, H.

    Filter papers and impaction substrates made of cellulose fibers, such as Whatman 41 and Misco P810/252, are of considerable utility in the collection of aerosol for subsequent trace elemental analysts. This experiment evaluated the performance of Misco P810/252 in collecting trace elements, relative to a co-located standard glass fiber filter hi-vol collection. Sampling was conducted in varying meteorological conditions, so that results might be expressed in terms of environmental variables such as temperature and relative humidity. The pass-through factors presented here were derived from a series of environmental samples collected over land and over water. Overall, the Misco impactor/filter failed to collect 38% of Pb and 32% of Zn.

  12. Organic analysis of ambient samples collected near Tank 241-C-103: Results from samples collected on May 12, 1994

    SciTech Connect

    Clauss, T.W.; Ligotke, M.W.; McVeety, B.D.; Lucke, R.B.; Young, J.S.; McCulloch, M.; Fruchter, J.S.; Goheen, S.C.

    1995-06-01

    This report describes organic analyses results from ambient samples collected both upwind and through the vapor sampling system (VSS) near Hanford waste storage Tank 241-C-103 (referred to as Tank C-103). The results described here were obtained to support safety and toxicological evaluations. A summary of the results for inorganic and organic analytes is listed. Quantitative results were obtained for organic compounds. Five organic tentatively identified compounds (TICS) were observed above the detection limit of (ca.) 10 ppbv, but standards for most of these were not available at the time of analysis, and the reported concentrations are semiquantitative estimates. In addition, we looked for the 40 standard TO-14 analytes. We observed 39. Of these, only one was observed above the 2-ppbv calibrated instrument detection limit. Dichloromethane was above the detection limits using both methods, but the result from the TO-14 method is traceable to a standard gas mixture and is considered more accurate. Organic analytes were found only in the sample collected through the VSS, suggesting that these compounds were residual contamination from a previous sampling job. Detailed descriptions of the results appear in the text.

  13. Particle morphologies and formation mechanisms of fine volcanic ash aerosol collected from the 2006 eruption of Augustine Volcano, Alaska

    NASA Astrophysics Data System (ADS)

    Rinkleff, P. G.; Cahill, C. F.

    2010-12-01

    Fine volcanic ash aerosol (35-0.09um) erupted in 2006 by Augustine Volcano, southwest of Anchorage, Alaska was collected by a DRUM cascade impactor and analyzed by scanning electron microscopy for individual particle chemistry and morphology. Results of these analyses show ash particles occur as either individual glass shard and mineral phase (plagioclase, magnetite, ilmenite, hornblende, etc.) particles or aggregates thereof. Individual glass shard ash particles are angular, uniformly-sized, consist of calc-alkaline whole-rock elements (Si, Al, Fe, Na, and Ca) and are not collocated on the sample media with non-silicate, Cl and S bearing sea salt particles. Aggregate particles occur as two types: pure ash aggregates and sea salt-cored aggregates. Pure ash aggregates are made up of only ash particles and contain no other constituents. Sea salt-cored aggregates are ash particles commingled with sea salts. Determining the formation processes of the different ash particle types need further investigation but some possibilities are proposed here. Individual ash particles may exist when the ambient air is generally dry, little electrical charge exists on ash particles, the eruptive cloud is generally dry, or the number of individual particles exceeds the scavenging capacity of the water droplets present. Another possibility is that ash aggregates may break apart as relative humidity drops over time and causes ash-laden water droplets to evaporate and subsequently break apart. Pure ash aggregates may form when the ambient air and plume is relatively dry but the ash has a significant charge to cause ash to aggregate. Or they could form during long-range transport when turbulent or Brownian motion can cause ash particles to collide and coagulate. Pure ash aggregates could also form as a result of water droplet scavenging and subsequent evaporation of water droplets, leaving behind only ash. In this case, droplets would not have interacted with a sea salt

  14. Predicting ambient aerosol Thermal Optical Reflectance (TOR) measurements from infrared spectra: elemental carbon

    NASA Astrophysics Data System (ADS)

    Dillner, A. M.; Takahama, S.

    2015-06-01

    Elemental carbon (EC) is an important constituent of atmospheric particulate matter because it absorbs solar radiation influencing climate and visibility and it adversely affects human health. The EC measured by thermal methods such as Thermal-Optical Reflectance (TOR) is operationally defined as the carbon that volatilizes from quartz filter samples at elevated temperatures in the presence of oxygen. Here, methods are presented to accurately predict TOR EC using Fourier Transform Infrared (FT-IR) absorbance spectra from atmospheric particulate matter collected on polytetrafluoroethylene (PTFE or Teflon) filters. This method is similar to the procedure tested and developed for OC in prior work (Dillner and Takahama, 2015). Transmittance FT-IR analysis is rapid, inexpensive, and non-destructive to the PTFE filter samples which are routinely collected for mass and elemental analysis in monitoring networks. FT-IR absorbance spectra are obtained from 794 filter samples from seven Interagency Monitoring of PROtected Visual Environment (IMPROVE) sites collected during 2011. Partial least squares regression is used to calibrate sample FT-IR absorbance spectra to collocated TOR EC measurements. The FTIR spectra are divided into calibration and test sets. Two calibrations are developed, one which is developed from uniform distribution of samples across the EC mass range (Uniform EC) and one developed from a~uniform distribution of low EC mass samples (EC < 2.4 μg, Low Uniform EC). A hybrid approach which applies the low EC calibration to low EC samples and the Uniform EC calibration to all other samples is used to produces predictions for low EC samples that have mean error on par with parallel TOR EC samples in the same mass range and an estimate of the minimum detection limit (MDL) that is on par with TOR EC MDL. For all samples, this hybrid approach leads to precise and accurate TOR EC predictions by FT-IR as indicated by high coefficient of variation (R2; 0.96), no

  15. Predicting ambient aerosol thermal-optical reflectance measurements from infrared spectra: elemental carbon

    NASA Astrophysics Data System (ADS)

    Dillner, A. M.; Takahama, S.

    2015-10-01

    Elemental carbon (EC) is an important constituent of atmospheric particulate matter because it absorbs solar radiation influencing climate and visibility and it adversely affects human health. The EC measured by thermal methods such as thermal-optical reflectance (TOR) is operationally defined as the carbon that volatilizes from quartz filter samples at elevated temperatures in the presence of oxygen. Here, methods are presented to accurately predict TOR EC using Fourier transform infrared (FT-IR) absorbance spectra from atmospheric particulate matter collected on polytetrafluoroethylene (PTFE or Teflon) filters. This method is similar to the procedure developed for OC in prior work (Dillner and Takahama, 2015). Transmittance FT-IR analysis is rapid, inexpensive and nondestructive to the PTFE filter samples which are routinely collected for mass and elemental analysis in monitoring networks. FT-IR absorbance spectra are obtained from 794 filter samples from seven Interagency Monitoring of PROtected Visual Environment (IMPROVE) sites collected during 2011. Partial least squares regression is used to calibrate sample FT-IR absorbance spectra to collocated TOR EC measurements. The FT-IR spectra are divided into calibration and test sets. Two calibrations are developed: one developed from uniform distribution of samples across the EC mass range (Uniform EC) and one developed from a uniform distribution of Low EC mass samples (EC < 2.4 μg, Low Uniform EC). A hybrid approach which applies the Low EC calibration to Low EC samples and the Uniform EC calibration to all other samples is used to produce predictions for Low EC samples that have mean error on par with parallel TOR EC samples in the same mass range and an estimate of the minimum detection limit (MDL) that is on par with TOR EC MDL. For all samples, this hybrid approach leads to precise and accurate TOR EC predictions by FT-IR as indicated by high coefficient of determination (R2; 0.96), no bias (0.00 μg m-3, a

  16. Validation and Uncertainty Estimates for MODIS Collection 6 "Deep Blue" Aerosol Data

    NASA Technical Reports Server (NTRS)

    Sayer, A. M.; Hsu, N. C.; Bettenhausen, C.; Jeong, M.-J.

    2013-01-01

    The "Deep Blue" aerosol optical depth (AOD) retrieval algorithm was introduced in Collection 5 of the Moderate Resolution Imaging Spectroradiometer (MODIS) product suite, and complemented the existing "Dark Target" land and ocean algorithms by retrieving AOD over bright arid land surfaces, such as deserts. The forthcoming Collection 6 of MODIS products will include a "second generation" Deep Blue algorithm, expanding coverage to all cloud-free and snow-free land surfaces. The Deep Blue dataset will also provide an estimate of the absolute uncertainty on AOD at 550 nm for each retrieval. This study describes the validation of Deep Blue Collection 6 AOD at 550 nm (Tau(sub M)) from MODIS Aqua against Aerosol Robotic Network (AERONET) data from 60 sites to quantify these uncertainties. The highest quality (denoted quality assurance flag value 3) data are shown to have an absolute uncertainty of approximately (0.086+0.56Tau(sub M))/AMF, where AMF is the geometric air mass factor. For a typical AMF of 2.8, this is approximately 0.03+0.20Tau(sub M), comparable in quality to other satellite AOD datasets. Regional variability of retrieval performance and comparisons against Collection 5 results are also discussed.

  17. AMBIENT AEROSOL CONCENTRATION BY CONDENSATION AND VIRTUAL IMPACTION FOR COLLECTION AND CHEMICAL ANALYSIS. (R825269)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  18. ELEMENTAL ANALYSIS OF SUB-HOURLY AMBIENT AEROSOL COLLECTIONS. (R825269)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  19. Molecular Characterization of Marine Organic Aerosols Collected during a Round-the-World Cruise

    NASA Astrophysics Data System (ADS)

    Fu, P.; Kawamura, K.; Miura, K.

    2010-12-01

    Total suspended particles (TSP) were collected on board the R/V Hakuho Maru during a round-the-world cruise (KH89-2) and were characterized for organic molecular compositions using solvent extraction/derivatization and gas chromatography/mass spectrometry technique. More than 140 organic species were detected in the marine aerosols and were grouped into 11 organic compound classes, including aliphatic lipids, anhydrosugars and sugar alcohols, lignin/resin acids, sterols, hopanes, polycyclic aromatic hydrocarbons, hydroxy-/polyacids, aromatic acids, as well as secondary organic aerosol (SOA) tracers from the photooxidation of biogenic volatile organic compounds. Concentrations of total quantified organics ranged from 0.94 to 98 ng m-3 (average 31 ng m-3) with higher concentrations in coastal regions (California Coast, South China Sea, and Western North Pacific) than in open marine areas (North Pacific and North Atlantic), suggesting that long-range atmospheric transport from the continents is the main source of marine organic aerosols. Isoprene SOA tracers, i.e., 2-methylglyceric acid, C5-alkene triols and 2-methyltetrols, were detected in all the samples (0.11-22 ng m-3, average 3.6 ng m-3) with higher concentrations in the tropical regions. They accounted for 0.48-29% of the total identified organics. Organic compounds were further categorized into several groups to clarify their sources. In the North Pacific and North Atlantic, secondary oxidation products (30-31%), fossil fuel combustion products (27-28%), as well as marine natural emissions (22-34%) were found as major contributors to the marine aerosols. In California Coast, North Indian Ocean and South China Sea, secondary oxidation products can contribute 44-55% of the total identified organics, followed by terrestrial natural emissions (12-27%), while biomass burning emissions were found to contribute only 1-2%. However, in the western North Pacific near the Asian continent, fossil fuel combustion (27%) and

  20. Model Evaluation of Aerosol Wet Scavenging in Deep Convective Clouds Based on Observations Collected during the DC3 Campaign

    NASA Astrophysics Data System (ADS)

    Yang, Q.; Easter, R. C.; Fast, J. D.; Wang, H.; Ghan, S. J.; Campuzano Jost, P.; Barth, M. C.; Fan, J.; Morrison, H.; Jimenez, J. L.; Bela, M. M.; Markovic, M. Z.

    2014-12-01

    Deep convective storms greatly influence the vertical distribution of aerosols by transporting aerosols from the boundary layer to the upper troposphere and by removing aerosols through wet scavenging processes. Model representation of wet scavenging is a major uncertainty in simulating the vertical distribution of aerosols due partly to limited constraints by observations. The effect of wet scavenging on ambient aerosols in deep mid-latitude continental convective clouds is studied for a severe storm case in the vicinity of the ARM Southern Great Plains site on May 29, 2012 during the Deep Convective Clouds and Chemistry Project (DC3) field campaign. A new budget analysis approach is developed to characterize the convective transport to the upper troposphere based on the vertical distribution of several slowly reacting and nearly insoluble trace gases (i.e., CO, acetone, and benzene). A similar budget framework is applied to aerosols combined with the known transport efficiency to estimate wet-scavenging efficiency. The chemistry version of the Weather Research and Forecasting model (WRF-Chem) simulates the storm initiation timing and structure reasonably well when compared against radar observations from the NSSL national 3-D reflectivity Mosaic data. Simulated vertical profiles of humidity and temperature also closely agree with radiosonde measurements before and during the storm. High scavenging efficiencies (~80%) for aerosol number (Dp < 2.5μm) and mass (Dp < 1μm) are obtained from the observations. Both observation analyses and the simulation show that, between the two dominant aerosol species, organic aerosol shows a slightly higher scavenging efficiency than sulfate aerosol, and higher scavenging efficiency is found for larger particle sizes (0.15 - 2.5μm versus 0.03 - 0.15μm). However, the model underestimates the wet scavenging efficiency (by up to 50%), in general, for both mass and number concentrations. The effect of neglecting secondary

  1. Direct and rapid analysis of ambient air and exhaled air via electrostatic precipitation of aerosols in an atomizer furnace and Zeeman spectrometry.

    PubMed

    Ivanenko, A A; Ivanenko, N B; Kuzmenkov, M A; Jakovleva, E M; Skudra, A; Slyadnev, M N; Ganeev, A A

    2005-02-01

    Techniques that allow the elements present in the air to be determined in a simple and rapid manner are very attractive. Direct aerosol sampling techniques avoid the need to pretreat the filter via wet digestion in order to remove any sources of contamination, and they decrease the precipitation time significantly. Analyzers based on this technique can also determine the concentrations of elements in the air automatically in situ. This paper is concerned with the development of a novel analytical system that is based on electrostatically precipitating aerosols from the air into a graphite furnace. The equipment includes a Zeeman spectrometer with high frequency modulation polarization (MGA-915), and an electrostatic precipitation system incorporated into the analyzer. The high sensitivity of the system developed here means that it can be used to determine element concentrations in the air exhaled by humans, as well as those in ambient air.

  2. Differences in the OC/EC Ratios that Characterize Ambient and Source Aerosols due to Thermal-Optical Analysis

    EPA Science Inventory

    Thermal-optical analysis (TOA) is typically used to measure the OC/EC (organic carbon/elemental carbon) and EC/TC (elemental carbon/total carbon) ratios in source and atmospheric aerosols. The present study utilizes a dual-optical carbon aerosol analyzer to examine the effects of...

  3. Four-year long-path monitoring of ambient aerosol extinction at a central European urban site: dependence on relative humidity

    NASA Astrophysics Data System (ADS)

    Skupin, A.; Ansmann, A.; Engelmann, R.; Seifert, P.; Müller, T.

    2016-02-01

    The ambient aerosol particle extinction coefficient is measured with the Spectral Aerosol Extinction Monitoring System (SÆMS) along a 2.84 km horizontal path at 30-50 m height above ground in the urban environment of Leipzig (51.3° N, 12.4° E), Germany, since 2009. The dependence of the particle extinction coefficient (wavelength range from 300 to 1000 nm) on relative humidity up to almost 100 % was investigated. The main results are presented. For the wavelength of 550 nm, the mean extinction enhancement factor was found to be 1.75 ± 0.4 for an increase of relative humidity from 40 to 80 %. The respective 4-year mean extinction enhancement factor is 2.8 ± 0.6 for a relative-humidity increase from 40 to 95 %. A parameterization of the dependency of the urban particle extinction coefficient on relative humidity is presented. A mean hygroscopic exponent of 0.46 for the 2009-2012 period was determined. Based on a backward trajectory cluster analysis, the dependence of several aerosol optical properties for eight air flow regimes was investigated. Large differences were not found, indicating that local pollution sources widely control the aerosol conditions over the urban site. The comparison of the SÆMS extinction coefficient statistics with respective statistics from ambient AERONET sun photometer observations yields good agreement. Also, time series of the particle extinction coefficient computed from in situ-measured dry particle size distributions and humidity-corrected SÆMS extinction values (for 40 % relative humidity) were found in good overall consistency, which verifies the applicability of the developed humidity parameterization scheme. The analysis of the spectral dependence of particle extinction (Ångström exponent) revealed an increase of the 390-881 nm Ångström exponent from, on average, 0.3 (at 30 % relative humidity) to 1.3 (at 95 % relative humidity) for the 4-year period.

  4. ANALYSIS OF SECONDARY ORGANIC AEROSOL COMPOUNDS FROM THE PHOTOOXIDATION OF D-LIMONENE IN THE PRESENCE OF NO X AND THEIR DETECTION IN AMBIENT PM 2.5

    EPA Science Inventory

    Chemical analysis of secondary organic aerosol (SOA) from the photooxidation of a d-limonene/NOx/air mixture was carried out. SOA, generated in a smog chamber, was collected on Zefluor filters. To determine the structural characteristics of the compounds, the filter sample...

  5. The Consistency of Isotopologues of Ambient Atmospheric Nitric Acid in Passively Collected Samples

    NASA Astrophysics Data System (ADS)

    Bell, M. D.; Sickman, J. O.; Bytnerowicz, A.; Padgett, P.; Allen, E. B.

    2012-12-01

    Anthropogenic sources of nitrogen oxides have previously been shown to have distinctive isotopic signatures of oxygen and nitrogen. Nylon filters are currently used in passive sampling arrays to measure ambient atmospheric nitric acid concentrations and estimate deposition rates. This experiment measured the ability of nylon filters to consistently collect isotopologues of atmospheric nitric acid in the same ratios as they are present in the atmosphere. Samplers were deployed in continuous stirred tank reactors (CSTR) and at field sites across a nitrogen deposition gradient in Southern California. Filters were exposed over a four week period with individual filters being subjected to 1-4 week exposure times. Extracted nitric acid were measured for δ18O and δ15N ratios and compared for consistency based on length of exposure and amount of HNO3 collected. Filters within the CSTRs collected HNO3 at a consistent rate in both high and low concentration chambers. After two weeks of exposure, the mean δ18O values were within 0.5‰ of the δ18O of the source HNO3 solution. The mean of all weekly exposures were within 0.5‰ of the δ15N of the source solution, but after three weeks, the mean δ15N of adsorbed HNO3 was within 0.2‰. As the length of the exposure increased, the variability of measured delta values decreased for both elements. The field samplers collected HNO3 consistent with previously measured values along a deposition gradient. The mean δ18O at high deposition sites was 52.2‰ compared to 35.7‰ at the low deposition sites. Mean δ15N values were similar at all sites across the deposition gradient. Due to precipitation events occurring during the exposure period, the δ15N and δ18O of nitric acid were highly variable at all field sites. At single sites, changes in δ15N and δ18O were negatively correlated, consistent with two-sourcing mixing dynamics, but the slope of the regressions differed between high and low deposition sites. Anthropogenic

  6. Ambient flow studies and particulate collection measurements: A laminar flow, reduced entrainment electrostatic precipitator

    SciTech Connect

    Greiner, G.P.; Furlong, D.A.; Bahner, M.A.

    1989-05-01

    This report describes ambient temperature testing of an electrostatic precipitator having a portion of the main precipitator flow drawn through porous (fabric) plates. The effects of flow through the plates (side flow) on precipitator turbulence and particulate removal efficiency are investigated. Ambient temperature particulate removal efficiency measurements are conducted on both indoor air dust, and on injected coal fly ash. 24 figs., 10 tabs.

  7. DETERMINATION OF SECONDARY ORGANIC AEROSOL PRODUCTS FROM THE PHOTOOXIDATION OF TOLUENE AND THEIR IMPLICATIONS IN AMBIENT PM2.5

    EPA Science Inventory

    Laboratory study was carried out to investigate the secondary organic aerosol products from photooxidation of the aromatic hydrocarbon toluene. The laboratory experiments consisted of irradiating toluene/propylene/NOX/air mixtures in a smog chamber operated in the dynamic mode...

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  9. 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.

  10. Effect of Vaporizer Temperature on Ambient Non-Refractory Submicron Aerosol Composition and Mass Spectra Measured by the Aerosol Mass Spectrometer

    EPA Science Inventory

    Aerodyne Aerosol Mass Spectrometers (AMS) are routinely operated with a constant vaporizer temperature (Tvap) of 600oC in order to facilitate quantitative detection of non-refractory submicron (NR-PM1) species. By analogy with other thermal desorption instrument...

  11. Chemical and statistical interpretation of sized aerosol particles collected at an urban site in Thessaloniki, Greece.

    PubMed

    Tsitouridou, Roxani; Papazova, Petia; Simeonova, Pavlina; Simeonov, Vasil

    2013-01-01

    The size distribution of aerosol particles (PM0.015-PM18) in relation to their soluble inorganic species and total water soluble organic compounds (WSOC) was investigated at an urban site of Thessaloniki, Northern Greece. The sampling period was from February to July 2007. The determined compounds were compared with mass concentrations of the PM fractions for nano (N: 0.015 < Dp < 0.06), ultrafine (UFP: 0.015 < Dp < 0.125), fine (FP: 0.015 < Dp < 2.0) and coarse particles (CP: 2.0 < Dp < 8.0) in order to perform mass closure of the water soluble content for the respective fractions. Electrolytes were the dominant species in all fractions (24-27%), followed by WSOC (16-23%). The water soluble inorganic and organic content was found to account for 53% of the nanoparticle, 48% of the ultrafine particle, 45% of the fine particle and 44% of the coarse particle mass. Correlations between the analyzed species were performed and the effect of local and long-range transported emissions was examined by wind direction and backward air mass trajectories. Multivariate statistical analysis (cluster analysis and principal components analysis) of the collected data was performed in order to reveal the specific data structure. Possible sources of air pollution were identified and an attempt is made to find patterns of similarity between the different sized aerosols and the seasons of monitoring. It was proven that several major latent factors are responsible for the data structure despite the size of the aerosols - mineral (soil) dust, sea sprays, secondary emissions, combustion sources and industrial impact. The seasonal separation proved to be not very specific. PMID:24007436

  12. Microanalysis of the aerosol collected over south-central New Mexico during the alive field experiment, May-December 1989

    NASA Astrophysics Data System (ADS)

    Sheridan, Patrick J.; Schnell, Russel C.; Kahl, Jonathan D.; Boatman, Joe F.; Garvey, Dennis M.

    Thirty-eight size-segregated aerosol samples were collected in the lower troposphere over the high desert of south-central New Mexico, using cascade impactors mounted onboard two research aircraft. Four of these samples were collected in early May, sixteen in mid-July, and the remaining ones in December 1989, during three segments of the ALIVE field initiative. Analytical electron microscope analyses of aerosol deposits and individual particles from these samples were performed to physically and chemically characterize the major particulate species present in the aerosol. Air-mass trajectories arriving at the sampling area in the May program were quite different from those calculated for the July period. In general, the May trajectories showed strong westerly winds, while the July winds were weaker and southerly, consistently passing over or very near the border cities of El Paso, Texas, and Ciudad Juarez, Mexico. Aerosol samples collected during the May period were predominantly fine (0.1-0.5 μm dia.), liquid H 2SO 4 droplets. Samples from the July experiment were comprised mostly of fine, solid (NH 4) 2SO 4 or mostly neutralized sulfate particles. In both sampling periods, numerous other particle classes were observed, including many types with probable terrestrial or anthropogenic sources. The numbers of these particles, however, were small when compared with the sulfates. Composite particle types, including sulfate/crustal and sulfate/carbonaceous, were also found to be present. The major differences in aerosol composition between the May and July samples (i.e. the extensive neutralization of sulfates in the July samples) can be explained by considering the different aerosol transport pathways and the proximity of the July aerosol to the El Paso/Juarez urban plume. Winds during the December experiment were quite variable, and may have contributed to the widely varying aerosol compositions observed in these samples. When the aircraft sampled the El Paso

  13. Electron Microanalysis of Aerosols Collected at Mauna Loa Observatory During an Asian Dust Storm Event

    NASA Astrophysics Data System (ADS)

    Conny, J. M.; Willis, R. D.; Ortiz-Montalvo, D. L.; Colton, A.

    2014-12-01

    Located in the remote marine free troposphere, the Mauna Loa Observatory (MLO) represents a clean airshed that can be used to study anthropogenic pollution influences and long-range transport of aerosol particles from the Asian mainland. Because of the global nature of Asian dust storms, the radiative properties of these particles transported long-range can significantly impact global climate. It has been proposed that aerosols transported to MLO during upslope wind conditions (typically daytime) are local in origin while aerosols transported during downslope conditions (typically nighttime) represent long-range transport in the free troposphere. Twelve PM10 samples (six daytime/nightime pairs) were collected on polycarbonate filters for 72 hours each between March 15 and April 26, 2011. Bulk samples of dust from local sources (road dust, parking lot, lava fields) were collected as well in order to assess the PM10 contribution from local dusts. On March 19-20 the Korea Meteorological Administration documented a significant dust event over the Korean peninsula. Back-trajectory analyses from MLO coupled with local wind speed and wind direction data suggest that this dust event may have been captured during the MLO sampling campaign. MLO samples were analyzed by computer-controlled scanning electron microscopy (CCSEM) coupled with energy-dispersive X-ray spectrometry (EDX) and particles were sorted into compositionally-distinct particle types which were then compared across the sample set. Concentrations of particle types expected to be associated with Asian dust were observed to peak in one pair of daytime/nighttime samples collected between March 22 and March 28. Manual microscopic characterization of suspected Asian dust particles and local dust particles was carried out using electron backscatter diffraction (EBSD) in conjunction with EDX and focussed ion beam SEM (FIB-SEM) in an effort to characterize differences in physicochemical or radiative properties of

  14. Retrieval of effective complex refractive index from intensive measurements of characteristics of ambient aerosols in the boundary layer.

    PubMed

    Zhang, Xiaolin; Huang, Yinbo; Rao, Ruizhong; Wang, Zhien

    2013-07-29

    Aerosol complex refractive index (ACRI) has attracted intensive attentions due to its significance in modeling aerosol radiative effects. Determinations of ACRI from surface measurements of aerosol scattering and absorption coefficients as well as number size distributions during June, 2008 based on an iterative Mie algorithm were performed. The aim of our study was to introduce an inversion approach with the merits of high time-resolutions to retrieve the optically effective ACRI, especially its imaginary part. Based on simultaneous measurements of aerosol characteristics, mean ACRI value of 1.50 ( ± 0.34)-i0.025 ( ± 0.015) at 550 nm in Hefei in summer was deducted. The lower imaginary parts with higher single scattering albedos and lower scattering Angstrom exponents were obtained for haze periods compared with nonhaze conditions with similar air-mass back-trajectories, indicating more large and scattering particles contributing to the formation of haze episodes. The derived imaginary parts of ACRI related to agricultural biomass burning were in the range from 0.013 to 0.029 at 550 nm. Significant negative correlations between retrieved imaginary parts of ACRI and measured single scattering albedos indicate that our retrieval approach is a reasonable method for determining the imaginary parts of complex refractive indices of aerosol particles.

  15. 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.

  16. Real-time measurements of secondary organic aerosol formation and aging from ambient air in an oxidation flow reactor in the Los Angeles area

    DOE PAGESBeta

    Ortega, Amber M.; Hayes, Patrick L.; Peng, Zhe; Palm, Brett B.; Hu, Weiwei; Day, Douglas A.; Li, Rui; Cubison, Michael J.; Brune, William H.; Graus, Martin; et al

    2016-06-15

    Field studies in polluted areas over the last decade have observed large formation of secondary organic aerosol (SOA) that is often poorly captured by models. The study of SOA formation using ambient data is often confounded by the effects of advection, vertical mixing, emissions, and variable degrees of photochemical aging. An oxidation flow reactor (OFR) was deployed to study SOA formation in real-time during the California Research at the Nexus of Air Quality and Climate Change (CalNex) campaign in Pasadena, CA, in 2010. A high-resolution aerosol mass spectrometer (AMS) and a scanning mobility particle sizer (SMPS) alternated sampling ambient andmore » reactor-aged air. The reactor produced OH concentrations up to 4 orders of magnitude higher than in ambient air. OH radical concentration was continuously stepped, achieving equivalent atmospheric aging of 0.8 days–6.4 weeks in 3 min of processing every 2 h. Enhancement of organic aerosol (OA) from aging showed a maximum net SOA production between 0.8–6 days of aging with net OA mass loss beyond 2 weeks. Reactor SOA mass peaked at night, in the absence of ambient photochemistry and correlated with trimethylbenzene concentrations. Reactor SOA formation was inversely correlated with ambient SOA and Ox, which along with the short-lived volatile organic compound correlation, indicates the importance of very reactive (τOH ~ 0.3 day) SOA precursors (most likely semivolatile and intermediate volatility species, S/IVOCs) in the Greater Los Angeles Area. Evolution of the elemental composition in the reactor was similar to trends observed in the atmosphere (O : C vs. H : C slope ~ –0.65). Oxidation state of carbon (OSc) in reactor SOA increased steeply with age and remained elevated (OSC ~ 2) at the highest photochemical ages probed. The ratio of OA in the reactor output to excess CO (ΔCO, ambient CO above regional background) vs. photochemical age is similar to previous studies at low to moderate ages and

  17. Real-time measurements of secondary organic aerosol formation and aging from ambient air in an oxidation flow reactor in the Los Angeles area

    NASA Astrophysics Data System (ADS)

    Ortega, Amber M.; Hayes, Patrick L.; Peng, Zhe; Palm, Brett B.; Hu, Weiwei; Day, Douglas A.; Li, Rui; Cubison, Michael J.; Brune, William H.; Graus, Martin; Warneke, Carsten; Gilman, Jessica B.; Kuster, William C.; de Gouw, Joost; Gutiérrez-Montes, Cándido; Jimenez, Jose L.

    2016-06-01

    Field studies in polluted areas over the last decade have observed large formation of secondary organic aerosol (SOA) that is often poorly captured by models. The study of SOA formation using ambient data is often confounded by the effects of advection, vertical mixing, emissions, and variable degrees of photochemical aging. An oxidation flow reactor (OFR) was deployed to study SOA formation in real-time during the California Research at the Nexus of Air Quality and Climate Change (CalNex) campaign in Pasadena, CA, in 2010. A high-resolution aerosol mass spectrometer (AMS) and a scanning mobility particle sizer (SMPS) alternated sampling ambient and reactor-aged air. The reactor produced OH concentrations up to 4 orders of magnitude higher than in ambient air. OH radical concentration was continuously stepped, achieving equivalent atmospheric aging of 0.8 days-6.4 weeks in 3 min of processing every 2 h. Enhancement of organic aerosol (OA) from aging showed a maximum net SOA production between 0.8-6 days of aging with net OA mass loss beyond 2 weeks. Reactor SOA mass peaked at night, in the absence of ambient photochemistry and correlated with trimethylbenzene concentrations. Reactor SOA formation was inversely correlated with ambient SOA and Ox, which along with the short-lived volatile organic compound correlation, indicates the importance of very reactive (τOH ˜ 0.3 day) SOA precursors (most likely semivolatile and intermediate volatility species, S/IVOCs) in the Greater Los Angeles Area. Evolution of the elemental composition in the reactor was similar to trends observed in the atmosphere (O : C vs. H : C slope ˜ -0.65). Oxidation state of carbon (OSc) in reactor SOA increased steeply with age and remained elevated (OSC ˜ 2) at the highest photochemical ages probed. The ratio of OA in the reactor output to excess CO (ΔCO, ambient CO above regional background) vs. photochemical age is similar to previous studies at low to moderate ages and also extends to

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  19. Impact of harbour emissions on ambient PM10 and PM2.5 in Barcelona (Spain): Evidences of secondary aerosol formation within the urban area.

    PubMed

    Pérez, Noemí; Pey, Jorge; Reche, Cristina; Cortés, Joaquim; Alastuey, Andrés; Querol, Xavier

    2016-11-15

    With the objective of estimating the impact of harbour activities on ambient PM10 and PM2.5 levels at the urban area of Barcelona, a one year long monitoring campaign was carried out in the context of the European APICE project (MED-FEDER-EC). This campaign was simultaneously conducted at the port and a central urban background site. A detailed PM10 and PM2.5 chemical speciation analysis was carried out with samples from both sites. Subsequently, a source apportionment analysis by means of the PMF receptor model was performed. Six common factors were identified, explaining local to regional emission sources (fuel oil combustion, industrial emissions, mineral-road dust resuspension, and road traffic emissions) and aerosol formation/transformation processes (secondary aerosols including ammonium sulphate and organic aerosols, and a mixed source accounting for aged sea spray and secondary nitrate). Around 50-55% PM10 and PM2.5 measured at the port was attributed to harbour activities: mineral matter from road dust and construction works of a new port area, vehicle traffic and fuel oil combustion. The estimated contribution of harbour emissions to the urban background reached 9-12% for PM10 and 11-15% for PM2.5 and is linked to primary emissions from fuel oil combustion but also to the formation of secondary aerosols. It becomes relevant to highlight the significantly higher contribution of secondary aerosols at the urban background when compared with the harbour site. Our hypothesis points to the fast formation of secondary ammonium sulphate within the city, after the reaction of SO2/H2SO4 transported by sea breezes with NH3, which is emitted in large amounts in Barcelona; and also to the enhanced formation of secondary organic aerosols within the city. This study broadens our knowledge on atmospheric phenomenology in urban Mediterranean cities and claims for effective abatement strategies focused on maritime practises, in agreement with the driving axis of the APICE

  20. Impact of harbour emissions on ambient PM10 and PM2.5 in Barcelona (Spain): Evidences of secondary aerosol formation within the urban area.

    PubMed

    Pérez, Noemí; Pey, Jorge; Reche, Cristina; Cortés, Joaquim; Alastuey, Andrés; Querol, Xavier

    2016-11-15

    With the objective of estimating the impact of harbour activities on ambient PM10 and PM2.5 levels at the urban area of Barcelona, a one year long monitoring campaign was carried out in the context of the European APICE project (MED-FEDER-EC). This campaign was simultaneously conducted at the port and a central urban background site. A detailed PM10 and PM2.5 chemical speciation analysis was carried out with samples from both sites. Subsequently, a source apportionment analysis by means of the PMF receptor model was performed. Six common factors were identified, explaining local to regional emission sources (fuel oil combustion, industrial emissions, mineral-road dust resuspension, and road traffic emissions) and aerosol formation/transformation processes (secondary aerosols including ammonium sulphate and organic aerosols, and a mixed source accounting for aged sea spray and secondary nitrate). Around 50-55% PM10 and PM2.5 measured at the port was attributed to harbour activities: mineral matter from road dust and construction works of a new port area, vehicle traffic and fuel oil combustion. The estimated contribution of harbour emissions to the urban background reached 9-12% for PM10 and 11-15% for PM2.5 and is linked to primary emissions from fuel oil combustion but also to the formation of secondary aerosols. It becomes relevant to highlight the significantly higher contribution of secondary aerosols at the urban background when compared with the harbour site. Our hypothesis points to the fast formation of secondary ammonium sulphate within the city, after the reaction of SO2/H2SO4 transported by sea breezes with NH3, which is emitted in large amounts in Barcelona; and also to the enhanced formation of secondary organic aerosols within the city. This study broadens our knowledge on atmospheric phenomenology in urban Mediterranean cities and claims for effective abatement strategies focused on maritime practises, in agreement with the driving axis of the APICE

  1. Online measurements of ambient fluorescent aerosol particles by WIBS at a polluted regional site in the North China Plain: potential impact of burning activities

    NASA Astrophysics Data System (ADS)

    Su, H.; Wang, Z.; Cheng, Y.; Xie, Z.; Kecorius, S.; McMeeking, G. R.; Yu, X.; Pöhlker, C.; Zhang, M.; Wiedensohler, A.; Kuhn, U.; Poeschl, U.; Huffman, J. A.

    2015-12-01

    Online measurements of ambient fluorescent aerosol particles by WIBS at a polluted regional site in the North China Plain: potential impact of burning activities Zhibin Wang1, Xiawei Yu1,3, Simonas Kecorius2, Zhouqing Xie3, Gavin McMeeking4, Christopher Pöhlker1, Minghui, Zhang1, Alfred Wiedensohler2, Uwe Kuhn1, Yafang Cheng1, Ulrich Pöschl1, Hang Su1,*1Multiphase Chemistry and Biogeochemistry Departments, Max Planck Institute for Chemistry, Mainz 55128, Germany2Leibniz-Institute for Tropospheric Research, Leipzig 04318, Germany3School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China4Droplet Measurement Technologies, Boulder 80301, USA ABSTRACTBioaerosols are the main subset of super-micron particles, and significantly influence the evolution of cloud and precipitation, as well as the public health. Currently, the detection of ambient biological materials in real-time is mainly based on the presence of fluorophores in the particles. In this study, we present the wideband integrated bioaerosol spectrometer (WIBS) measurement results to characterize the fluorescent aerosol particles (FAP) at a polluted regional site (Xianghe, 39.80 °N, 116.96 °E) in the North China Plain. We observed substantially much higher number concentration of FAP as compared with those of previous studies in clean environments. We found the good agreement between the FAP number fraction in coarse mode particles (> 1 mm) and BC mass fraction in fine particles (< 1 mm), possibly indicating a majority of the observed FAP is to a certain extent related to the anthropogenic burning activities nearby. This interference and uncertainty should be especially noticed when performing fluorescence measurements in the polluted area, where the certain non-biological compounds (such as SOA, PAH and soot) may significantly lead to a positive fluorescence measurement artifacts and an overestimation of actual fluorescent biological aerosol particles. We also

  2. Aerosol-Assisted Solid Debris Collection for the National Ignition Facility

    SciTech Connect

    Nelson, S L; Shaughnessy, D A; Moody, K J; Ivanov, V V; Astanovitskiy, A L; Lewis, L A; Rundberg, R S

    2010-05-21

    The National Ignition Facility (NIF) has been completed and has made its first shots on-target. While upcoming experiments will be focused on achieving ignition, a variety of subsequent experiments are planned for the facility, including measurement of cross sections, astrophysical measurements, and investigation of hydrodynamic instability in the target capsule. In order to successfully execute several of these planned experiments, the ability to collect solid debris following a NIF capsule shot will be required. The ability to collect and analyze solid debris generated in a shot at the National Ignition Facility (NIF) will greatly expand the number of nuclear reactions studied for diagnostic purposes. Currently, reactions are limited to only those producing noble gases for cryogenic collection and counting with the Radchem Apparatus for Gas Sampling (RAGS). The radchem solid collection diagnostic has already been identified by NIF to be valuable for the determination and understanding of mix generated in the target capsule's ablation. LLNL is currently developing this solid debris collection capability at NIF, and is in the stage of testing credible designs. Some of these designs explore the use of x-ray generated aerosols to assist in collection of solid debris. However, the variety of harsh experimental conditions this solid collection device will encounter in NIF are challenging to replicate. Experiments performed by Gary Grim et al. at Sandia National Laboratory's RHEPP1 facility have shown that ablation causes a cloud of material removed from an exposed surface to move normal to and away from the surface. This ablation is certain to be a concern in the NIF target chamber from the prompt x-rays, gamma rays, etc. generated in the shot. The cloud of ablated material could interfere with the collection of the desired reaction debris by slowing down the debris so that the kinetic energy is too low to allow implantation, or by stopping the debris from reaching the

  3. The Detroit Exposure and Aerosol Research Study (DEARS) - Article in National Ambient Air Quality Status and Trends through 2007

    EPA Science Inventory

    A research study that the U.S. Environmental Protection Agency conducted in Detroit, Michigan, named the Detroit Exposure and Aerosol Research Study (DEARS), will help develop data that improves our understanding of human exposure to various air pollutants in our environment.

  4. 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.

  5. Correlations between absorption Angström exponent (AAE) of wintertime ambient urban aerosol and its physical and chemical properties

    NASA Astrophysics Data System (ADS)

    Utry, N.; Ajtai, T.; Filep, Á.; Pintér, M.; Török, Zs.; Bozóki, Z.; Szabó, G.

    2014-07-01

    Based on a two-week measurement campaign in an environment heavily polluted both by transit traffic and household heating in the inner city of Szeged (Hungary), correlations between the absorption Angström exponent (AAE) fitted to the optical absorption coefficients measured with a four wavelength (1064, 532, 355 and 266 nm) photoacoustic aerosol measuring system (4λ-PAS) and various aerosol parameters were identified. AAE was found to depend linearly on OCwb/EC and on NGM100/NGMD20, i.e. on the ratio of mass concentrations of elemental carbon (EC) to the fraction of organic carbon associated with wood burning (OCwb), and on the ratio of aerosol number concentrations in the 20 nm (NGMD20) to 100 nm (NGMD100) modes, with a regression coefficient of R = 0.95 and R = 0.86, respectively. In the daily fluctuation of AAE two minima were identified, which coincide with the morning and afternoon rush hours, during which NGMD20 exhibits maximum values. During the campaign the shape of the aerosol volume size distribution (dV/dlogD) was found to be largely invariant, supporting the assumption that the primary driver for the AAE variation was aerosol chemical composition rather than particle size. Furthermore, when wavelength segregated AAE values were calculated, AAE for the shorter wavelengths (AAE355-266) was also found to depend linearly on the above mentioned ratios with similar regression coefficients but with a much steeper correlation line, while the AAE for the longer wavelengths (AAE1064-532) exhibits only a considerably weaker correlation. These results prove the unique advantages of real time multi-wavelength photoacoustic measurement of optical absorption in case the wavelength range includes the ultra-violet too.

  6. Assessing the impact of anthropogenic pollution on isoprene-derived secondary organic aerosol formation in PM2.5 collected from the Birmingham, Alabama, ground site during the 2013 Southern Oxidant and Aerosol Study

    NASA Astrophysics Data System (ADS)

    Rattanavaraha, Weruka; Chu, Kevin; Hapsari Budisulistiorini, Sri; Riva, Matthieu; Lin, Ying-Hsuan; Edgerton, Eric S.; Baumann, Karsten; Shaw, Stephanie L.; Guo, Hongyu; King, Laura; Weber, Rodney J.; Neff, Miranda E.; Stone, Elizabeth A.; Offenberg, John H.; Zhang, Zhenfa; Gold, Avram; Surratt, Jason D.

    2016-04-01

    In the southeastern US, substantial emissions of isoprene from deciduous trees undergo atmospheric oxidation to form secondary organic aerosol (SOA) that contributes to fine particulate matter (PM2.5). Laboratory studies have revealed that anthropogenic pollutants, such as sulfur dioxide (SO2), oxides of nitrogen (NOx), and aerosol acidity, can enhance SOA formation from the hydroxyl radical (OH)-initiated oxidation of isoprene; however, the mechanisms by which specific pollutants enhance isoprene SOA in ambient PM2.5 remain unclear. As one aspect of an investigation to examine how anthropogenic pollutants influence isoprene-derived SOA formation, high-volume PM2.5 filter samples were collected at the Birmingham, Alabama (BHM), ground site during the 2013 Southern Oxidant and Aerosol Study (SOAS). Sample extracts were analyzed by gas chromatography-electron ionization-mass spectrometry (GC/EI-MS) with prior trimethylsilylation and ultra performance liquid chromatography coupled to electrospray ionization high-resolution quadrupole time-of-flight mass spectrometry (UPLC/ESI-HR-QTOFMS) to identify known isoprene SOA tracers. Tracers quantified using both surrogate and authentic standards were compared with collocated gas- and particle-phase data as well as meteorological data provided by the Southeastern Aerosol Research and Characterization (SEARCH) network to assess the impact of anthropogenic pollution on isoprene-derived SOA formation. Results of this study reveal that isoprene-derived SOA tracers contribute a substantial mass fraction of organic matter (OM) ( ˜ 7 to ˜ 20 %). Isoprene-derived SOA tracers correlated with sulfate (SO42-) (r2 = 0.34, n = 117) but not with NOx. Moderate correlations between methacrylic acid epoxide and hydroxymethyl-methyl-α-lactone (together abbreviated MAE/HMML)-derived SOA tracers with nitrate radical production (P[NO3]) (r2 = 0.57, n = 40) were observed during nighttime, suggesting a potential role of the NO3 radical in

  7. Molecular size evolution of oligomers in organic aerosols collected in urban atmospheres and generated in a smog chamber.

    PubMed

    Kalberer, Markus; Sax, Mirjam; Samburova, Vera

    2006-10-01

    Only a minor fraction of the total organic aerosol mass can be resolved on a molecular level. High molecular weight compounds in organic aerosols have recently gained much attention because this class of compound potentially explains a major fraction of the unexplained organic aerosol mass. These compounds have been identified with different mass spectrometric methods, and compounds with molecular masses up to 1000 Da are found in secondary organic aerosols (SOA) generated from aromatic and terpene precursors in smog chamber experiments. Here, we apply matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) to SOA particles from two biogenic precursors, alpha-pinene and isoprene. Similar oligomer patterns are found in these two SOA systems, but also in SOA from trimethylbenzene, an anthropogenic SOA precursor. However, different maxima molecular sizes were measured for these three SOA systems. While oligomers in alpha-pinene and isoprene have sizes mostly below 600-700 Da, they grow up to about 1000 Da in trimethylbenzene-SOA. The final molecular size of the oligomers is reached early during the particle aging process, whereas other particle properties related to aging, such as the overall acid concentration or the oligomer concentration, increase continuously over a much longer time scale. This kinetic behavior of the oligomer molecular size growth can be explained by a chain growth kinetic regime. Similar oligomer mass patterns were measured in aqueous extracts of ambient aerosol samples (measured with the same technique). Distinct differences between summer and winter were observed. In summer a few single mass peaks were measured with much higher intensity than in winter, pointing to a possible difference in the formation processes of these compounds in winter and summer.

  8. Characterization of ambient and extracted PM2.5 collected on filters for toxicology applications.

    PubMed

    Roper, Courtney; Chubb, Lauren G; Cambal, Leah; Tunno, Brett; Clougherty, Jane E; Mischler, Steven E

    2015-01-01

    Research on the health effects of fine particulate matter (PM2.5) frequently disregards the differences in particle composition between that measured on an ambient filter versus that measured in the corresponding extraction solution used for toxicological testing. This study presents a novel method for characterizing the differences, in metallic and organic species, between the ambient samples and the corresponding extracted solutions through characterization of extracted PM2.5 suspended on filters. Removal efficiency was found to be 98.0 ± 1.4% when measured using pre- and post-removal filter weights, however, this efficiency was significantly reduced to 80.2 ± 0.8% when measured based on particle mass in the extraction solution. Furthermore, only 47.2 ± 22.3% of metals and 24.8 ± 14.5% of organics measured on the ambient filter were found in the extraction solution. Individual metallic and organic components were extracted with varying efficiency, with many organics being lost entirely during extraction. Finally, extraction efficiencies of specific PM2.5 components were inversely correlated with total mass. This study details a method to assess compositional alterations resulting from extraction of PM2.5 from filters, emphasizing the need for standardized procedures that maintain compositional integrity of ambient samples for use in toxicology studies of PM2.5. PMID:26446919

  9. VERSATILE AEROSOL CONCENTRATION ENRICHMENT SYSTEM (VACES) FOR SIMULTANEOUS IN VIVO AND IN VITRO EVALUATION OF TOXIC EFFECTS OF ULTRAFINE, FINE AND COARSE AMBIENT PARTICLES. PART I: DEVELOPMENT AND LABORATORY CHARACTERIZATION. (R827352C001)

    EPA Science Inventory

    This study presents the development and bench-testing of a versatile aerosol concentration enrichment system (VACES) capable of simultaneously concentrating ambient particles of the coarse, fine and ultrafine size fractions for conducting in vivo and in vitro studies. The VACE...

  10. VERSATILE AEROSOL CONCENTRATION ENRICHMENT SYSTEM (VACES) FOR SIMULTANEOUS IN-VIVO AND IN-VITRO EVALUATION OF TOXIC EFFECTS OF ULTRAFINE, FINE, AND COARSE AMBIENT PARTICLES. PART II. FIELD EVALUATION. (R826232)

    EPA Science Inventory

    Abstract

    This study presents results from a field evaluation of a mobile versatile aerosol concentration enrichment system (VACES), designed to enhance the ambient concentrations of ultrafine (less than 0.18 VERSATILE AEROSOL CONCENTRATION ENRICHMENT SYSTEM (VACES) FOR SIMULTANEOUS IN VIVO AND IN VITRO EVALUATION OF TOXIC EFFECTS OF ULTRAFINE, FINE AND COARSE AMBIENT PARTICLES. PART II: FIELD EVALUATION. (R827352C001)

    EPA Science Inventory

    This study presents results from a field evaluation of a mobile versatile aerosol concentration enrichment system (VACES), designed to enhance the ambient concentrations of ultrafine (less than 0.18 small m...</p>
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      <p><a target=A study of the physical, chemical, and optical properties of ambient aerosol particles in Southeast Asia during hazy and nonhazy days

    NASA Astrophysics Data System (ADS)

    See, S. W.; Balasubramanian, R.; Wang, W.

    2006-05-01

    Many Southeast Asian countries have been constantly plagued by recurring smoke haze episodes as a result of traditional slash-and-burn practices in agricultural areas to clear crop lands or uncontrolled forest fires. However, our current knowledge on the physiochemical and optical properties of ambient aerosols associated with regional haze phenomenon is still fairly limited. Therefore a comprehensive field study was carried out in Singapore from March 2001 to March 2002 under varying weather conditions to gain a better understanding of the characteristics. The physical (size distribution of mass and number concentrations), chemical (mass concentrations of chemical components: 14 ions, 24 metals, elemental carbon (EC) and organic carbon (OC)), and optical (light absorption (bap) and scattering (bsp) by particles) characteristics of ambient aerosol particles were investigated. The results are reported separately for clear and hazy days by categorizing the days as clear or hazy on the basis of visibility data. It was observed that the average concentrations of PM2.5 and most chemical components increased approximately by a factor of 2 on hazy days. Backward air trajectories together with the hot spot distributions in the region indicated that the degradation in Singapore's air quality on hazy days was attributable to large-scale forest fires in Sumatra. This visibility degradation was quantitatively measured on the basis of the light absorption and scattering by particles. As expected, scattering rather than absorption controlled atmospheric visibility, and PM2.5 particles present on hazy days were more efficient at scattering light than those found on clear days.

  11. Spatial and Temporal Characteristics of Aerosols from Collection 6 Aqua and Terra MODIS e-Deep Blue Products

    NASA Astrophysics Data System (ADS)

    Bettenhausen, C.; Hsu, N. Y. C.; Sayer, A. M.; Lee, J.; Carletta, N.

    2015-12-01

    Aerosols continue to attract a significant amount of attention from researchers worldwide due to their extensive effects on Earth's climate, ecology, public health, and even energy production. In order to truly understand these effects, a long, stable, and well-calibrated data record is required. Since 2000 and 2002, the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments aboard the Terra and Aqua satellites together with the e-Deep Blue aerosol retrieval algorithm have been providing such a data record. After a multi-year development effort, the production of both Aqua and Terra MODIS Collection 6 (C6) atmosphere products successfully completed earlier this year and the data was released to the public shortly thereafter. The C6 Deep Blue products (now enhanced Deep Blue or e-Deep Blue) have been significantly improved over the previous Collection 5.1 version. In this poster we provide an overview of the latest C6 e-Deep Blue products and the improvements implemented since the previous collection including coverage over dark surfaces and updates to the Terra calibration. Validation results utilizing Aerosol Robotic Network (AERONET) data are also summarized. We then use the C6 e-Deep Blue products from both Aqua and Terra to explore the spatial characteristics in addition to the seasonal and inter-annual variability of aerosols on both regional and global scales. We also use this as an opportunity to compare these results and investigate any differences found between the two instruments.

  12. Contributions of modern and dead organic carbon to individual fatty acid homologues in spring aerosols collected from northern Japan

    NASA Astrophysics Data System (ADS)

    Kawamura, Kimitaka; Matsumoto, Kohei; Uchida, Masao; Shibata, Yasuyuki

    2010-11-01

    Radiocarbon (14C) and stable carbon isotope ratios (δ13C) have been used as proxies to evaluate the contributions of modern/fossil carbon and marine/terrestrial organic matter, respectively, in geochemical samples. However, there are few such studies in atmospheric aerosols. Here, we measured 14C contents and δ13C of individual n-fatty acids in an aerosol sample collected from northern Japan in spring 2001 during Asian dust season. Our results show that the distribution of fatty acids in the spring aerosols was characterized by a strong even/odd carbon number predominance with two maxima at C16 and C26. Their δ13C (range: -30.6 to -20.5‰) showed higher values (average: -24.5‰) for lower molecular weight (LMW) fatty acids (C16 - C19) and lower values (average: -29.7‰) for higher MW (HMW) fatty acids (C20 - C32). This difference suggests that LMW acids are mainly derived from lacustrine and/or marine algal sources whereas HMW acids are predominantly from terrestrial C3 higher plants. Δ14C values of fatty acids were found to range from -96.9 to +122.9‰ with lower values for HMW acids and higher values for LMW acids. LMW acids in the aerosols contain only modern carbon. In contrast, HMW acids ≥C24 were found to contain up to 9.7 wt% dead carbon, although their major portion (up to 92.3%) is composed of modern carbon. Backward trajectory analyses indicated that the source regions of the spring aerosols were dominated by central and north China (62%). This study suggests that the old fatty acids in the spring aerosols are most likely originated from the loess deposits in China via long-range atmospheric transport over the western North Pacific, although their contribution to the aerosols was relatively small.

  13. On the role of particle inorganic mixing state in the reactive uptake of N2O5 to ambient aerosol particles.

    PubMed

    Ryder, Olivia S; Ault, Andrew P; Cahill, John F; Guasco, Timothy L; Riedel, Theran P; Cuadra-Rodriguez, Luis A; Gaston, Cassandra J; Fitzgerald, Elizabeth; Lee, Christopher; Prather, Kimberly A; Bertram, Timothy H

    2014-01-01

    The rates of heterogeneous reactions of trace gases with aerosol particles are complex functions of particle chemical composition, morphology, and phase state. Currently, the majority of model parametrizations of heterogeneous reaction kinetics focus on the population average of aerosol particle mass, assuming that individual particles have the same chemical composition as the average state. Here we assess the impact of particle mixing state on heterogeneous reaction kinetics using the N2O5 reactive uptake coefficient, γ(N2O5), and dependence on the particulate chloride-to-nitrate ratio (nCl(-)/nNO3(-)). We describe the first simultaneous ambient observations of single particle chemical composition and in situ determinations of γ(N2O5). When accounting for particulate nCl(-)/nNO3(-) mixing state, model parametrizations of γ(N2O5) continue to overpredict γ(N2O5) by more than a factor of 2 in polluted coastal regions, suggesting that chemical composition and physical phase state of particulate organics likely control γ(N2O5) in these air masses. In contrast, direct measurement of γ(N2O5) in air masses of marine origin are well captured by model parametrizations and reveal limited suppression of γ(N2O5), indicating that the organic mass fraction of fresh sea spray aerosol at this location does not suppress γ(N2O5). We provide an observation-based framework for assessing the impact of particle mixing state on gas-particle interactions.

  14. Sugars as source indicators of biogenic organic carbon in aerosols collected above the Howland Experimental Forest, Maine

    NASA Astrophysics Data System (ADS)

    Medeiros, Patricia M.; Conte, Maureen H.; Weber, John C.; Simoneit, Bernd R. T.

    Bulk aerosols (>1 μm) were collected continuously above the canopy at the Howland Experimental Forest, Maine, USA from May to October 2002. Each sample integrated over an approximately 2-week period. Mono- and disaccharide sugars were extracted using a microscale technique and were analyzed as their TMS derivatives by gas chromatography-mass spectrometry (GC-MS). Concentrations of total aerosol sugars ranged from 10 to 180 ng m -3. Glucose was the most abundant sugar (40-75% of the total sugars). The monosaccharides arabinose, fructose, galactose, mannose, arabitol and mannitol, and the disaccharides sucrose, maltose and mycose (aka trehalose) were also present in lower concentrations. The sugar composition in the aerosols varied seasonally. Fructose and sucrose were prevalent in early spring and decreased in relative abundance as the growing season progressed. Sugar polyols (arabitol and mannitol) and the disaccharide mycose (a fungal metabolite) were more prevalent in autumn during the period of leaf senescence. The changes in the sugar composition in the aerosol samples appear to reflect the seasonality of sugar production and utilization by the ecosystem. Plant waxes were present as significant components also indicating an input from biogenic background. Smoke plumes from Quebec forest fires passed over the Howland site in early July 2002. Levoglucosan, a biomarker of biomass burning, increased by an order of magnitude in the aerosol samples collected during this time. Glucose, mannose, arabinose, galactose, and also, plant waxes increased in concentration by factors of 2-5 in the smoke-impacted samples, indicating that wildfires enhance atmospheric emissions of uncombusted organic compounds. In contrast, concentrations of fructose, sugar polyols and disaccharides were not significantly higher in the smoke-impacted samples and indicated that biomass burning was not a significant source of these compounds in the aerosols.

  15. Aerosols and environmental pollution

    NASA Astrophysics Data System (ADS)

    Colbeck, Ian; Lazaridis, Mihalis

    2010-02-01

    The number of publications on atmospheric aerosols has dramatically increased in recent years. This review, predominantly from a European perspective, summarizes the current state of knowledge of the role played by aerosols in environmental pollution and, in addition, highlights gaps in our current knowledge. Aerosol particles are ubiquitous in the Earth’s atmosphere and are central to many environmental issues; ranging from the Earth’s radiative budget to human health. Aerosol size distribution and chemical composition are crucial parameters that determine their dynamics in the atmosphere. Sources of aerosols are both anthropogenic and natural ranging from vehicular emissions to dust resuspension. Ambient concentrations of aerosols are elevated in urban areas with lower values at rural sites. A comprehensive understanding of aerosol ambient characteristics requires a combination of measurements and modeling tools. Legislation for ambient aerosols has been introduced at national and international levels aiming to protect human health and the environment.

  16. Aerosols and environmental pollution.

    PubMed

    Colbeck, Ian; Lazaridis, Mihalis

    2010-02-01

    The number of publications on atmospheric aerosols has dramatically increased in recent years. This review, predominantly from a European perspective, summarizes the current state of knowledge of the role played by aerosols in environmental pollution and, in addition, highlights gaps in our current knowledge. Aerosol particles are ubiquitous in the Earth's atmosphere and are central to many environmental issues; ranging from the Earth's radiative budget to human health. Aerosol size distribution and chemical composition are crucial parameters that determine their dynamics in the atmosphere. Sources of aerosols are both anthropogenic and natural ranging from vehicular emissions to dust resuspension. Ambient concentrations of aerosols are elevated in urban areas with lower values at rural sites. A comprehensive understanding of aerosol ambient characteristics requires a combination of measurements and modeling tools. Legislation for ambient aerosols has been introduced at national and international levels aiming to protect human health and the environment.

  17. Effects of aerosol collection and extraction procedures on the optical properties of water-soluble organic compounds

    NASA Astrophysics Data System (ADS)

    Mladenov, N.; Alados-Arboledas, L.; Olmo Reyes, F. J.; Reche, I.

    2009-12-01

    Water-soluble organic compounds (WSOC) are routinely collected using active and passive aerosol samplers and, after extraction in water, analyzed using UV-vis absorbance and fluorescence techniques. These analyses provide important information regarding the chemical character and sources of aerosols worldwide. To evaluate the effects of various aerosol collection and processing methods on the optical properties of WSOC, two-dimensional absorption spectra from 200 to 900 nm and three-dimensional fluorescence excitation-emission spectra (EEMs) from 240 to 450 nm excitation and 300 to 560 nm emission were analyzed in samples obtained simultaneously with different procedures. Samples included: milli-Q purified water passed through 140 mm diameter glass fiber and quartz fiber filters used in high volume PM10 aerosol samplers, 47 mm glass fiber filters used for organic matter analyses, and mixed cellulose 0.2 micron and 0.015 micron filters used for bacterial and viral filtration, respectively; milli-Q purified water rinsed in plastic buckets used for passive wet and dry deposition collection; and WSOC samples extracted from filters by soaking, sonication, and agitation. Parallel factor analysis (PARAFAC) modeling of WSOC was performed to quantify the influence of various collection and extraction procedures on fluorescence signatures. All filters examined were found to leach some amount of fluorescent compounds (Figure 1). Mixed cellulose filters, especially those with small pore size, leached substantially more amino acid-like and humic-like material than other filters, whereas leaching from quartz fiber filters used for high volume aerosol collection was minimal (Figure 1). Fluorescence intensities of filter leachates decreased with increased rinsing of filters, indicating that rinsing with purified water prior to filtration is advisable, even for pre-combusted filters. Dissolved organic carbon concentrations of WSOC extracted from filters by sonication, agitation

  18. An assessment of the performance of the Monitor for AeRosols and GAses in ambient air (MARGA): a semi-continuous method for soluble compounds

    NASA Astrophysics Data System (ADS)

    Rumsey, I. C.; Cowen, K. A.; Walker, J. T.; Kelly, T. J.; Hanft, E. A.; Mishoe, K.; Rogers, C.; Proost, R.; Beachley, G. M.; Lear, G.; Frelink, T.; Otjes, R. P.

    2013-09-01

    Ambient air monitoring as part of the US Environmental Protection Agency's (US EPA's) Clean Air Status and Trends Network (CASTNet) currently uses filter packs to measure weekly integrated concentrations. The US EPA is interested in supplementing CASTNet with semi-continuous monitoring systems at select sites to characterize atmospheric chemistry and deposition of nitrogen and sulfur compounds at higher time resolution than the filter pack. The Monitor for AeRosols and GAses in ambient air (MARGA) measures water-soluble gases and aerosols at hourly temporal resolution. The performance of the MARGA was assessed under the US EPA Environmental Technology Verification (ETV) program. The assessment was conducted in Research Triangle Park, North Carolina from 8 September-8 October 2010 and focused on gaseous SO2, HNO3 and NH3 and aerosol SO4-, NO3- and NH4+. Precision of the MARGA was evaluated by calculating the median absolute relative percent difference (MARPD) between paired hourly results from duplicate MARGA units (MUs), with a performance goal of <25%. The accuracy of the MARGA was evaluated by calculating the median absolute relative percent difference (MARPD) for each MU relative to the average of the duplicate denuder/filter pack concentrations, with a performance goal of ≤40%. Accuracy was also evaluated by using linear regression, where MU concentrations were plotted against the average of the duplicate denuder/filter pack concentrations. From this, a linear least squares line of best fit was applied. The goal was for the slope of the line of best fit to be between 0.8 and 1.2. The MARGA performed well in comparison to the denuder/filter pack for SO2, SO42- and NH4+, with all three compounds passing the accuracy and precision goals by a significant margin. The performance of the MARGA in measuring NO3- could not be evaluated due to the different sampling efficiency of coarse NO3- by the MUs and the filter pack. Estimates of "fine" NO3- were calculated for

  1. An assessment of the performance of the Monitor for AeRosols and GAses in ambient air (MARGA): a semi-continuous method for soluble compounds

    NASA Astrophysics Data System (ADS)

    Rumsey, I. C.; Cowen, K. A.; Walker, J. T.; Kelly, T. J.; Hanft, E. A.; Mishoe, K.; Rogers, C.; Proost, R.; Beachley, G. M.; Lear, G.; Frelink, T.; Otjes, R. P.

    2014-06-01

    Ambient air monitoring as part of the US Environmental Protection Agency's (US EPA's) Clean Air Status and Trends Network (CASTNet) currently uses filter packs to measure weekly integrated concentrations. The US EPA is interested in supplementing CASTNet with semi-continuous monitoring systems at select sites to characterize atmospheric chemistry and deposition of nitrogen and sulfur compounds at higher time resolution than the filter pack. The Monitor for AeRosols and GAses in ambient air (MARGA) measures water-soluble gases and aerosols at an hourly temporal resolution. The performance of the MARGA was assessed under the US EPA Environmental Technology Verification (ETV) program. The assessment was conducted in Research Triangle Park, North Carolina, from 8 September to 8 October 2010 and focused on gaseous SO2, HNO3, and NH3 and aerosol SO42-, NO3-, and NH4+. Precision of the MARGA was evaluated by calculating the median absolute relative percent difference (MARPD) between paired hourly results from duplicate MARGA units (MUs), with a performance goal of ≤ 25%. The accuracy of the MARGA was evaluated by calculating the MARPD for each MU relative to the average of the duplicate denuder/filter pack concentrations, with a performance goal of ≤ 40%. Accuracy was also evaluated by using linear regression, where MU concentrations were plotted against the average of the duplicate denuder/filter pack concentrations. From this, a linear least squares line of best fit was applied. The goal was for the slope of the line of best fit to be between 0.8 and 1.2. The MARGA performed well in comparison to the denuder/filter pack for SO2, SO42-, and NH4+, with all three compounds passing the accuracy and precision goals by a significant margin. The performance of the MARGA in measuring NO3- could not be evaluated due to the different sampling efficiency of coarse NO3- by the MUs and the filter pack. Estimates of "fine" NO3- were calculated for the MUs and the filter pack

  2. Molecular composition of the water-soluble fraction of atmospheric carbonaceous aerosols collected during ACE-Asia

    NASA Astrophysics Data System (ADS)

    Mader, B. T.; Yu, J. Z.; Xu, J. H.; Li, Q. F.; Wu, W. S.; Flagan, R. C.; Seinfeld, J. H.

    2004-03-01

    During the Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia), samples of carbonaceous aerosols were collected on board the Center for Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS) De Havilland DHC-6 Twin Otter aircraft. The samples were analyzed to determine their total carbon (TC) and water-soluble organic compound (WSOC) contents as well as to identify the individual compounds comprising the WSOC fraction of the aerosol. The TC concentrations varied from 3.5 to 14.3 μg C m-3; the highest TC levels were observed for samples collected in pollution layers that originated over mainland China. WSOC concentrations ranged from 0.54 to 7.2 μg C m-3, with the WSOC fraction contributing from 10 to 50% of the carbon mass. About 50% of the carbonaceous aerosol mass in pollution layers could be attributed to WSOC. For samples collected in dust layers the WSOC fraction of TC was much lower than that observed in pollution layers. The sum of all the detected organic ions accounted for 6.9-19% of the WSOC. In the six samples collected by the Twin Otter during ACE-Asia, of the organic ions identified in the WSOC fraction, oxalate had the highest concentration. Samples collected from pollution layers exhibited a slightly higher ratio of formate to oxalate as compared to the other samples. Two samples had a relatively high ratio of lactate to oxalate, which might be a signature of some currently unidentified source of carbonaceous aerosol. The sum of the masses of sulfate and nitrate ions exceeded the sum of the masses of the identified organic ions by a factor of 9 to 17. The chemical levoglucosan, a tracer for biomass burning, comprised from 0.1 to 0.4% of TC mass. Comparing this ratio to the ratio measured directly in wood-burning studies it was determined that biomass burning may have represented from ≈2 to 10% of the carbonaceous aerosol collected during ACE-Asia.

  3. EPR investigation of iron in size segregated atmospheric aerosols collected at Dunkerque, Northern France

    NASA Astrophysics Data System (ADS)

    Ledoux, Frédéric; Zhilinskaya, Elena A.; Courcot, Dominique; Aboukaı̈s, Antoine; Puskaric, Emile

    Electron paramagnetic resonance (EPR) spectroscopy was used to study atmospheric aerosols at Dunkerque, a French sea-side city located on the southern coast of the North Sea. Particles were collected in June-July 2001 and January-February 2002 periods using global filtration and cascade impaction. EPR spectra obtained for these particles were attributed to Fe 3+ ions, mainly in the form of hematite ( α-Fe 2O 3) in interaction with other paramagnetic species (Fe 3+, Mn 2+, Cu 2+, etc.). From the EPR spectra intensities measured at 77 and 293 K, Fe 3+ ions were evidenced in the form of clusters and agglomerated species. Fe 3+ agglomerated species were observed mainly for winds blowing from the industrial park. Cascade impactor samples study evidenced that clusters are rather detected in the small size particles whereas agglomerated Fe 3+ ions species are rather present in the large ones. The small size particles are richer in iron than the large ones, thus such particles play an important role in the value of EPR parameters.

  4. Experimental study of elementary collection efficiency of aerosols by spray: Design of the experimental device

    SciTech Connect

    Ducret, D.; Vendel, J.; Garrec. S.L.

    1995-02-01

    The safety of a nuclear power plant containment building, in which pressure and temperature could increase because of a overheating reactor accident, can be achieved by spraying water drops. The spray reduces the pressure and the temperature levels by condensation of steam on cold water drops. The more stringent thermodynamic conditions are a pressure of 5.10{sup 5} Pa (due to steam emission) and a temperature of 413 K. Moreover its energy dissipation function, the spray leads to the washout of fission product particles emitted in the reactor building atmosphere. The present study includes a large program devoted to the evaluation of realistic washout rates. The aim of this work is to develop experiments in order to determine the collection efficiency of aerosols by a single drop. To do this, the experimental device has to be designed with fundamental criteria:-Thermodynamic conditions have to be representative of post-accident atmosphere. Thermodynamic equilibrium has to be attained between the water drops and the gaseous phase. Thermophoretic, diffusiophoretic and mechanical effects have to be studied independently. Operating conditions have to be homogenous and constant during each experiment. This paper presents the design of the experimental device. In practice, the consequences on the design of each of the criteria given previously and the necessity of being representative of the real conditions will be described.

  5. A method for the direct measurement of surface tension of collected atmospherically relevant aerosol particles using atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Hritz, Andrew D.; Raymond, Timothy M.; Dutcher, Dabrina D.

    2016-08-01

    Accurate estimates of particle surface tension are required for models concerning atmospheric aerosol nucleation and activation. However, it is difficult to collect the volumes of atmospheric aerosol required by typical instruments that measure surface tension, such as goniometers or Wilhelmy plates. In this work, a method that measures, ex situ, the surface tension of collected liquid nanoparticles using atomic force microscopy is presented. A film of particles is collected via impaction and is probed using nanoneedle tips with the atomic force microscope. This micro-Wilhelmy method allows for direct measurements of the surface tension of small amounts of sample. This method was verified using liquids, whose surface tensions were known. Particles of ozone oxidized α-pinene, a well-characterized system, were then produced, collected, and analyzed using this method to demonstrate its applicability for liquid aerosol samples. It was determined that oxidized α-pinene particles formed in dry conditions have a surface tension similar to that of pure α-pinene, and oxidized α-pinene particles formed in more humid conditions have a surface tension that is significantly higher.

  6. Effect of face velocity and the nature of aerosol on the collection of submicrometer particles by electrostatic precipitator.

    PubMed

    Morawska, L; Agranovski, V; Ristovski, Z; Jamriska, M

    2002-06-01

    Despite the electrostatic collection of aerosol particles as one of the most widely used air cleaning methods, there has not been sufficient amount of effort devoted to investigate its performance in the full range of operating conditions. This paper reports results of the tests of a two-stage electrostatic precipitator (ESP) conducted in the particle size range of 0.018-1.2 microns over a range of flow rates using NaCl and Environmental Tobacco Smoke (ETS) test aerosols. The total collection efficiency of the precipitator was found to increase with an increase in the count median diameter (CMD) of the particles, to have polynomial dependence on flow rate and no significant dependence on the type of test aerosol. The fractional efficiency of the precipitator was found to be dependent on flow rate. However, the 'critical' particle size of about 1.2 microns was found to exist when the fractional collection efficiency becomes independent of flow rate. For submicrometer particles, the collection efficiency was found to be independent of particle size at flow rates below 560 l/s. A minimum in the efficiency was observed in the 0.1-0.45 micron particle size range and for particles smaller than about 0.02 micron.

  7. Compositional variability of the aerosols collected on Kerkennah Islands (central Tunisia)

    NASA Astrophysics Data System (ADS)

    Trabelsi, A.; Masmoudi, M.; Quisefit, J. P.; Alfaro, S. C.

    2016-03-01

    The aim of the present study is to investigate the seasonal variability of the aerosol concentrations and origins in central Tunisia. Four field campaigns were carried out in 2010/2011 to collect air-suspended particles on the Kerkennah Islands. The elemental composition (Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, Cr, Mn, Fe, Cu, Zn, Pb, Ni, V, and As) of the particles collected in summer (June and July), autumn (September and November), winter (February and March), and spring (April and May) is determined by X-ray fluorescence analysis. Examination of the enrichment factors (EF) of all elements indicate that Al, Fe, Si, Ca, Ti, Mn, and Cr are mainly derived from soil sources, whereas Na and Cl are mostly of marine origin. Other elements such as K and Mg or S and P have multiple origins (Marine/crustal and crustal/anthropogenic, respectively). Finally, V, Cu, Ni, As, and Pb appear to be produced by anthropogenic activities. Based on the inter-elemental correlations, the mass concentrations of mineral dust (MD), sea-salt (SS) and anthropogenic (non-crustal and non-marine) sulfates (NSS) are quantified. MD, SS and NSS display significant inter-seasonal differences: on the one hand, MD and SS are the highest in spring and the lowest in winter, probably because of the seasonal change in meteorological conditions. On the other hand, NSS and Cu concentrations are above their autumn and winter values in spring and summer, which suggests the existence of a common source of the combustion type for these two pollutants.

  8. Biomass burning as an important source of reactive oxygen species associated with the atmospheric aerosols in Southeastern United States - Implications for health effects of ambient particulate matter

    NASA Astrophysics Data System (ADS)

    Verma, V.; Weber, R. J. J.; Fang, T.; Xu, L.; Ng, N. L.; Russell, A. G.

    2014-12-01

    We assessed the potential of water-soluble fraction of atmospheric fine aerosols in the southeastern US to generate reactive oxygen species (ROS). ROS-generation potential of particles was quantified by the dithiothreitol (DTT) assay and involved analysis of fine particulate matter (PM) extracted from high-volume quartz filters (23 h integrated daily samples) collected for one year at various sites in different environmental settings in the southeast, including three urban Atlanta sites, and one rural site in Yorkville. Water-soluble PM extracts were further separated into the hydrophobic and hydrophilic fractions using a C-18 column, and both fractions were analyzed for the DTT activity. Organic aerosol (OA) composition was measured at selected sites using a High-Resolution Time-of-Flight Aerosol Mass Spectrophotometer (HR-ToF-AMS). The various factors of the organic aerosols, i.e. Isoprene OA (Isop-OA), hydrocarbon-like OA (HOA), less-oxidized oxygenated OA, (LO-OOA), more-oxidized OOA (MO-OOA), cooking OA (COA), and biomass burning OA (BBOA) were also resolved, and their ability to generate ROS investigated by linear regression techniques. Among all OA factors, BBOA was most consistently associated with ROS, with the highest intrinsic DTT activity of 151±20 pmol/min/μg. The water-soluble bioavailable fraction of BBOA-DTT activity is 2-3 times higher than the reported total-DTT activity of diesel exhaust particles. The total contribution of various aerosol sources to the ROS generating potential was also determined by the positive matrix factorization approach. Interestingly, biomass burning appears as the strongest source of ROS generation, with its annual contribution of 35 % to DTT activity; the contribution was higher in winter (47 %), than summer (24 %) and fall (17 %) seasons. The good agreement between the hydrophobic DTT activity with that estimated from the summed OA components, indicates that humic-like substances (HULIS), which are abundantly emitted

  9. Molecular characterization of S- and N-containing organic constituents in ambient aerosols by negative ion mode high-resolution Nanospray Desorption Electrospray Ionization Mass Spectrometry: CalNex 2010 field study

    NASA Astrophysics Data System (ADS)

    O'Brien, Rachel E.; Laskin, Alexander; Laskin, Julia; Rubitschun, Caitlin L.; Surratt, Jason D.; Goldstein, Allen H.

    2014-11-01

    Samples of ambient aerosols from the 2010 California Research at the Nexus of Air Quality and Climate Change (CalNex) field study were analyzed using negative ion mode Nanospray Desorption Electrospray Ionization High-Resolution Mass Spectrometry (nano-DESI/MS). Four samples per day (6 h each) were collected in Bakersfield, CA on 20-24 June. Four characteristic groups were identified: molecules composed of carbon, hydrogen, and oxygen only (CHO), sulfur- (CHOS), nitrogen- (CHON), and both nitrogen- and sulfur-containing organics (CHONS). The chemical formula and elemental ratios were consistent with the presence of organonitrates, organosulfate, and nitroxy organosulfates in the negative ion mode mass spectra. The number of observed CHO compounds increased in the afternoon samples, suggesting photochemical processing as a source. The average number of CHOS compounds had the smallest changes during the day, consistent with a more broadly distributed source. Both of the nitrogen-containing groups (CHONS and CHON) had greater numbers of compounds in the early morning (midnight to 6 A.M.) and night (6 P.M. to midnight) samples, respectively, consistent with nitrate radical chemistry as a likely source for those compounds. Most of the compounds were found in submicron particles. The size distribution of the number of CHON compounds was bimodal, potentially indicating two types of sources. We conclude that the majority of the compounds observed were secondary in nature with both biogenic and anthropogenic sources. These data are complementary to previous results from positive ion mode nano-DESI/MS analysis of a subset of the same samples providing a more complete view of aerosol chemical composition at Bakersfield.

  10. Biological aerosol background characterization

    NASA Astrophysics Data System (ADS)

    Blatny, Janet; Fountain, Augustus W., III

    2011-05-01

    To provide useful information during military operations, or as part of other security situations, a biological aerosol detector has to respond within seconds or minutes to an attack by virulent biological agents, and with low false alarms. Within this time frame, measuring virulence of a known microorganism is extremely difficult, especially if the microorganism is of unknown antigenic or nucleic acid properties. Measuring "live" characteristics of an organism directly is not generally an option, yet only viable organisms are potentially infectious. Fluorescence based instruments have been designed to optically determine if aerosol particles have viability characteristics. Still, such commercially available biological aerosol detection equipment needs to be improved for their use in military and civil applications. Air has an endogenous population of microorganisms that may interfere with alarm software technologies. To design robust algorithms, a comprehensive knowledge of the airborne biological background content is essential. For this reason, there is a need to study ambient live bacterial populations in as many locations as possible. Doing so will permit collection of data to define diverse biological characteristics that in turn can be used to fine tune alarm algorithms. To avoid false alarms, improving software technologies for biological detectors is a crucial feature requiring considerations of various parameters that can be applied to suppress alarm triggers. This NATO Task Group will aim for developing reference methods for monitoring biological aerosol characteristics to improve alarm algorithms for biological detection. Additionally, they will focus on developing reference standard methodology for monitoring biological aerosol characteristics to reduce false alarm rates.

  11. Global Estimates of Ambient Fine Particulate Matter Concentrations from Satellite-Based Aerosol Optical Depth: Development and Application

    PubMed Central

    van Donkelaar, Aaron; Martin, Randall V.; Brauer, Michael; Kahn, Ralph; Levy, Robert; Verduzco, Carolyn; Villeneuve, Paul J.

    2010-01-01

    Background Epidemiologic and health impact studies of fine particulate matter with diameter < 2.5 μm (PM2.5) are limited by the lack of monitoring data, especially in developing countries. Satellite observations offer valuable global information about PM2.5 concentrations. Objective In this study, we developed a technique for estimating surface PM2.5 concentrations from satellite observations. Methods We mapped global ground-level PM2.5 concentrations using total column aerosol optical depth (AOD) from the MODIS (Moderate Resolution Imaging Spectroradiometer) and MISR (Multiangle Imaging Spectroradiometer) satellite instruments and coincident aerosol vertical profiles from the GEOS-Chem global chemical transport model. Results We determined that global estimates of long-term average (1 January 2001 to 31 December 2006) PM2.5 concentrations at approximately 10 km × 10 km resolution indicate a global population-weighted geometric mean PM2.5 concentration of 20 μg/m3. The World Health Organization Air Quality PM2.5 Interim Target-1 (35 μg/m3 annual average) is exceeded over central and eastern Asia for 38% and for 50% of the population, respectively. Annual mean PM2.5 concentrations exceed 80 μg/m3 over eastern China. Our evaluation of the satellite-derived estimate with ground-based in situ measurements indicates significant spatial agreement with North American measurements (r = 0.77; slope = 1.07; n = 1057) and with noncoincident measurements elsewhere (r = 0.83; slope = 0.86; n = 244). The 1 SD of uncertainty in the satellite-derived PM2.5 is 25%, which is inferred from the AOD retrieval and from aerosol vertical profile errors and sampling. The global population-weighted mean uncertainty is 6.7 μg/m3. Conclusions Satellite-derived total-column AOD, when combined with a chemical transport model, provides estimates of global long-term average PM2.5 concentrations. PMID:20519161

  12. Technical Note: A novel rocket-based in situ collection technique for mesospheric and stratospheric aerosol particles

    NASA Astrophysics Data System (ADS)

    Reid, W.; Achtert, P.; Ivchenko, N.; Magnusson, P.; Kuremyr, T.; Shepenkov, V.; Tibert, G.

    2013-03-01

    A technique for collecting aerosol particles between altitudes of 17 and 85 km is described. Spin-stabilized collection probes are ejected from a sounding rocket allowing for multi-point measurements. Each probe is equipped with 110 collection samples that are 3 mm in diameter. The collection samples are one of three types: standard transmission electron microscopy carbon grids, glass fibre filter paper or silicone gel. Collection samples are exposed over a 50 m to 5 km height range with a total of 45 separate ranges. Post-flight electron microscopy will give size-resolved information on particle number, shape and elemental composition. Each collection probe is equipped with a suite of sensors to capture the probe's status during the fall. Parachute recovery systems along with GPS-based localization will ensure that each probe can be located and recovered for post-flight analysis.

  13. Recovery of Pasteurella hemolytica from aerosols at differing temperature and humidity.

    PubMed Central

    Jericho, K W; Langford, E V; Pantekoek, J

    1977-01-01

    A Pasteurella hemolytica suspension with fetal calf serum was aerosolized in a standard system with ambient temperature of 30 or 2 degrees C and relative humidity conditions of 90 or 60%. The number of organisms sprayed in five minutes and the number recovered from one third of the aerosol during these five minutes was determined. Recoveries were influenced by temperature difference between aerosol and collecting fluid. Recoveries ranged between 0.059--0.94%. Images Fig. 1. PMID:861840

  14. 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

  15. Laboratory studies of collection efficiency of sub-micrometer aerosol particles by cloud droplets on a single droplet basis

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    An experimental setup has been constructed to measure the Collection Efficiency (CE) of sub-micrometer aerosol particles by cloud droplets. Water droplets of a dilute aqueous ammonium sulfate solution with a radius of ~20 μm fall freely into a chamber and collide with sub-micrometer Polystyrene Latex Sphere (PSL) particles of variable size and concentrations. Two RH conditions, ~15 and ~88%, hereafter termed "Low" and "High", respectively, were varied with different particles size and concentrations. After passing through the chamber, the droplets and aerosol particles were sent to the Particle Analysis by Laser Mass Spectrometry (PALMS) instrument to determine chemical compositions on a single particle basis. Coagulated droplets had mass spectra that contain signatures from both an aerosol particle and a droplet residual. CE values range from 5.7 × 10-3 to 4.6 × 10-2 for the Low RH and from 6.4 × 10-3 to 2.2 × 10-2 for the High RH cases. CE values were, within experimental uncertainty, independent of the aerosol concentrations. CE values in this work were found to be in agreement with previous experimental and theoretical studies. To our knowledge, this is the first coagulation experiment performed on a single droplet basis.

  16. Individual particle analysis of aerosols collected at Lhasa City in the Tibetan Plateau.

    PubMed

    Duo, Bu; Zhang, Yunchen; Kong, Lingdong; Fu, Hongbo; Hu, Yunjie; Chen, Jianmin; Li, Lin; Qiong, A

    2015-03-01

    To understand the composition and major sources of aerosol particles in Lhasa City on the Tibetan Plateau (TP), individual particles were collected from 2 February to 8 March, 2013 in Tibet University. The mean concentrations of both PM2.5 and PM10 during the sampling were 25.7±21.7 and 57.2±46.7 μg/m3, respectively, much lower than those of other cities in East and South Asia, but higher than those in the remote region in TP like Nam Co, indicating minor urban pollution. Combining the observations with the meteorological parameters and back trajectory analysis, it was concluded that local sources controlled the pollution during the sampling. Transmission electron microscopy (TEM) combined with energy-dispersive X-ray spectra (EDS) was used to study 408 particles sampled on four days. Based on the EDS analysis, a total of 8 different particle categories were classified for all 408 particles, including Si-rich, Ca-rich, soot, K-rich, Fe-rich, Pb-rich, Al-rich and other particles. The dominant elements were Si, Al and Ca, which were mainly attributed to mineral dust in the earth's crust such as feldspar and clay. Fe-, Pb-, K-, Al-rich particles and soot mainly originated from anthropogenic sources like firework combustion and biomass burning during the sampling. During the sampling, the pollution mainly came from mineral dust, while the celebration ceremony and religious ritual produced a large quantity of anthropogenic metal-bearing particles on 9 and 25 February 2013. Cement particles also had a minor influence. The data obtained in this study can be useful for developing pollution control strategies.

  17. Individual particle analysis of aerosols collected at Lhasa City in the Tibetan Plateau.

    PubMed

    Duo, Bu; Zhang, Yunchen; Kong, Lingdong; Fu, Hongbo; Hu, Yunjie; Chen, Jianmin; Li, Lin; Qiong, A

    2015-03-01

    To understand the composition and major sources of aerosol particles in Lhasa City on the Tibetan Plateau (TP), individual particles were collected from 2 February to 8 March, 2013 in Tibet University. The mean concentrations of both PM2.5 and PM10 during the sampling were 25.7±21.7 and 57.2±46.7 μg/m3, respectively, much lower than those of other cities in East and South Asia, but higher than those in the remote region in TP like Nam Co, indicating minor urban pollution. Combining the observations with the meteorological parameters and back trajectory analysis, it was concluded that local sources controlled the pollution during the sampling. Transmission electron microscopy (TEM) combined with energy-dispersive X-ray spectra (EDS) was used to study 408 particles sampled on four days. Based on the EDS analysis, a total of 8 different particle categories were classified for all 408 particles, including Si-rich, Ca-rich, soot, K-rich, Fe-rich, Pb-rich, Al-rich and other particles. The dominant elements were Si, Al and Ca, which were mainly attributed to mineral dust in the earth's crust such as feldspar and clay. Fe-, Pb-, K-, Al-rich particles and soot mainly originated from anthropogenic sources like firework combustion and biomass burning during the sampling. During the sampling, the pollution mainly came from mineral dust, while the celebration ceremony and religious ritual produced a large quantity of anthropogenic metal-bearing particles on 9 and 25 February 2013. Cement particles also had a minor influence. The data obtained in this study can be useful for developing pollution control strategies. PMID:25766026

  18. Ambient Tropospheric Particles

    EPA Science Inventory

    Atmospheric particulate matter (PM) is a complex mixture of solid and liquid particles suspended in ambient air (also known as the atmospheric aerosol). Ambient PM arises from a wide-range of sources and/or processes, and consists of particles of different shapes, sizes, and com...

  19. EVALUATION OF SOLID ADSORBENTS FOR THE COLLECTION AND ANALYSES OF AMBIENT BIOGENIC VOLATILE ORGANICS

    EPA Science Inventory

    Micrometeorological flux measurements of biogenic volatile organic compounds (BVOCs) usually require that large volumes of air be collected (whole air samples) or focused during the sampling process (cryogenic trapping or gas-solid partitioning on adsorbents) in order to achiev...

  20. Behavior of Particulate Mercury in the Bulk Atmospheric Aerosols Simultaneously Collected at 2 Sites in Okinawa, Japan

    NASA Astrophysics Data System (ADS)

    Miyagi, Y.; Arakaki, T.; Azechi, S.; Somada, Y.; Oshiro, Y.; Tsuhako, A.; Murayama, H.; Tanahara, A.

    2013-12-01

    Mercury is toxic to animals. Mercury is emitted to the atmosphere mainly from two sources; natural and anthropogenic sources. Natural sources include volcanic eruption, forest fire and so on. Anthropogenic sources include fossil fuel combustion, metal and cement production and so on. There are three forms of mercury in the atmosphere: gaseous elemental mercury, reactive gaseous mercury and particulate mercury. Gaseous elemental mercury is the most abundant form in the atmosphere, and has long atmospheric lifetime, ca. a few years. This study focuses on particulate mercury, which has a relatively short lifetime, ca. a few days, in the atmosphere because it reflects characteristics of nearby emission sources. Objectives of this study were to elucidate the behavior of particulate mercury in aerosols and to understand relationships between mercury and other metals and water-soluble anions. Aerosol samples were collected at two sites; Cape Hedo Atmosphere and Aerosol Monitoring Station (CHAAMS, Jan.2008-Nov.2012), northern tip of Okinawa island, and University of the Ryukyus (UR, Jan.2008-Nov.2012), central and more populated area of Okinawa island. They were collected by using identical high-volume air samplers on quartz filters. Concentrations of particulate mercury in aerosols were determined by using a MA-3000 (Nippon Instruments Corporation). The results showed that particulate Hg concentrations were mostly higher for the aerosols collected at UR site than those at CHAAMS site, suggesting locally emitted Hg. Samples collected at UR showed clear seasonal variation, the lowest in summer and the highest winter. On the other hand, the CHAAMS samples showed lower concentration in winter and higher concentration in summer, but the difference was relatively small. Both UR and CHAAMS samples had similar concentration levels in summer season. Back trajectory analysis showed that particulate Hg at CHAAMS site during summer was not from Asian continent. Since samples

  1. Assessment of primary and secondary ambient particle trends using satellite aerosol optical depth and ground speciation data in the New England region, United States.

    PubMed

    Lee, Hyung Joo; Kang, Choong-Min; Coull, Brent A; Bell, Michelle L; Koutrakis, Petros

    2014-08-01

    The effectiveness of air pollution emission control policies can be evaluated by examining ambient pollutant concentration trends that are observed at a large number of ground monitoring sites over time. In this paper, we used ground monitoring measurements in conjunction with satellite aerosol optical depth (AOD) data to investigate fine particulate matter (PM2.5; particulate matter with aerodynamic diameter ≤ 2.5 µm) trends and their spatial patterns over a large U.S. region, New England, during 2000-2008. We examined the trends in rural and urban areas to get a better insight about the trends of regional and local source emissions. Decreases in PM2.5 concentrations (µg/m(3)) were more pronounced in urban areas than in rural ones. In addition, the highest and lowest PM2.5 decreases (µg/m(3)) were observed for winter and summer, respectively. Together, these findings suggest that primary particle concentrations decreased more relative to secondary ones. This is also supported by the analysis of the speciation data which showed that downward trends of primary pollutants including black carbon were stronger than those of secondary pollutants including sulfate. Furthermore, this study found that ambient primary pollutants decreased at the same rate as their respective source emissions. This was not the case for secondary pollutants which decreased at a slower rate than that of their precursor emissions. This indicates that concentrations of secondary pollutants depend not only on the primary emissions but also on the availability of atmospheric oxidants which might not change during the study period. This novel approach of investigating spatially varying concentration trends, in combination with ground PM2.5 species trends, can be of substantial regulatory importance.

  2. Assessment of primary and secondary ambient particle trends using satellite aerosol optical depth and ground speciation data in the New England region, United States

    PubMed Central

    Lee, Hyung Joo; Kang, Choong-Min; Coull, Brent A.; Bell, Michelle L.; Koutrakis, Petros

    2014-01-01

    The effectiveness of air pollution emission control policies can be evaluated by examining ambient pollutant concentration trends that are observed at a large number of ground monitoring sites over time. In this paper, we used ground monitoring measurements in conjunction with satellite aerosol optical depth (AOD) data to investigate fine particulate matter (PM2.5; particulate matter with aerodynamic diameter ≤2.5 μm) trends and their spatial patterns over a large U.S. region, New England, during 2000–2008. We examined the trends in rural and urban areas to get a better insight about the trends of regional and local source emissions. Decreases in PM2.5 concentrations (μg/m3) were more pronounced in urban areas than in rural ones. In addition, the highest and lowest PM2.5 decreases (μg/m3) were observed for winter and summer, respectively. Together, these findings suggest that primary particle concentrations decreased more relative to secondary ones. This is also supported by the analysis of the speciation data which showed that downward trends of primary pollutants including black carbon were stronger than those of secondary pollutants including sulfate. Furthermore, this study found that ambient primary pollutants decreased at the same rate as their respective source emissions. This was not the case for secondary pollutants which decreased at a slower rate than that of their precursor emissions. This indicates that concentrations of secondary pollutants depend not only on the primary emissions but also on the availability of atmospheric oxidants which might not change during the study period. This novel approach of investigating spatially varying concentration trends, in combination with ground PM2.5 species trends, can be of substantial regulatory importance. PMID:24906074

  3. Levoglucosan and Lipid Class Compounds in the Asian Dusts and Marine Aerosols Collected During the ACE-Asia Campaign

    NASA Astrophysics Data System (ADS)

    Kobayashi, M.; Simoneit, B. R.; Kawamura, K.; Mochida, M.; Lee, M.; Lee, G.; Huebert, B. J.

    2002-12-01

    In order to characterize organic aerosols in the Asian Pacific region, we collected filter samples at Gosan (formerly Kosan) and Sapporo sites as well as on mobile platforms (R.V. R.H. Brown and NCAR C-130) in the western North Pacific. The aerosol extracts were analyzed by capillary GC-MS employing a TMS derivatization technique. We identified over 100 organic compounds in the samples. They are categorized into seven different classes in terms of functional groups and sources. First, sugar-type compounds were detected in the aerosols, including levoglucosan, galactosan and mannosan, which are tracers for biomass burning. Second, a homologous series of fatty acids (C12-C30) and fatty alcohols (C12-C30) mainly from plant waxes and marine lipids were present. The third group includes dicarboxylic acids (>C3) and other atmospheric oxidation products. Although oxalic (C2) and malonic (C3) acids were not detected by this method, they are very abundant in the aerosols. The fourth group includes n-alkanes (C18-C35) which usually showed a strong odd/even predominance, suggesting an important contribution from higher plant waxes. The fifth includes polynuclear aromatic hydrocarbons (PAH) ranging from phenanthrene to coronene, all combustion products of petroleum and mainly coal. Saccharides were the sixth group and consisted mainly of a- and b- glucose, sucrose and its alditol, and minor amounts of xylitol, sorbitol and arabitol. These saccharides are tracers for soil dust. Phthalates were detected as the seventh class, with a dominance of dioctyl phthalate. The results suggest that organic aerosols originate primarily from (1) natural emissions of terrestrial plant wax and marine lipids, (2) smoke from biomass burning (mainly non-conifer fuels), (3) soil resuspension due to spring agricultural activity, (4) urban/industrial emissions from fossil fuel use (coal), and (5) secondary reaction products. These compounds are transported by the strong westerly winds and therefore

  4. Comparison Between NPP-VIIRS Aerosol Data Products and the MODIS AQUA Deep Blue Collection 6 Dataset Over Land

    NASA Technical Reports Server (NTRS)

    Sayer, Andrew M.; Hsu, N. C.; Bettenhausen, C.; Lee, J.; Kondragunta, S.

    2013-01-01

    Aerosols are small particles suspended in the atmosphere and have a variety of natural and man-made sources. Knowledge of aerosol optical depth (AOD), which is a measure of the amount of aerosol in the atmosphere, and its change over time, is important for multiple reasons. These include climate change, air quality (pollution) monitoring, monitoring hazards such as dust storms and volcanic ash, monitoring smoke from biomass burning, determining potential energy yields from solar plants, determining visibility at sea, estimating fertilization of oceans and rainforests by transported mineral dust, understanding changes in weather brought upon by the interaction of aerosols and clouds, and more. The Suomi-NPP satellite was launched late in 2011. The Visible Infrared Imaging Radiometer Suite (VIIRS) aboard Suomi-NPP is being used, among other things, to determine AOD. This study compares the VIIRS dataset to ground-based measurements of AOD, along with a state-of-the-art satellite AOD dataset (the new version of the Moderate Resolution Imaging Spectrometer Deep Blue algorithm) to assess its reliability. The Suomi-NPP satellite was launched late in 2011, carrying several instruments designed to continue the biogeophysical data records of current and previous satellite sensors. The Visible Infrared Imaging Radiometer Suite (VIIRS) aboard Suomi-NPP is being used, among other things, to determine aerosol optical depth (AOD), and related activities since launch have been focused towards validating and understanding this new dataset through comparisons with other satellite and ground-based products. The operational VIIRS AOD product is compared over land with AOD derived from Moderate Resolution Imaging Spectrometer (MODIS) observations using the Deep Blue (DB) algorithm from the forthcoming Collection 6 of MODIS data

  5. 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

    2012-09-01

    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 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

  6. Quantitative ED-EPMA combined with morphological information for the characterization of individual aerosol particles collected in Incheon, Korea

    NASA Astrophysics Data System (ADS)

    Kang, SuJin; Hwang, HeeJin; Kang, Sunni; Park, YooMyung; Kim, HyeKyeong; Ro, Chul-Un

    A quantitative single-particle analytical technique, called low- Z particle electron probe X-ray microanalysis, combined with the utilization of their morphological information on individual particles, was applied to characterize six aerosol samples collected in one Korean city, Incheon, during March 9-15, 2006. The collected supermicron aerosol particles were classified based on their chemical species and morphology on a single-particle basis. Many different particle types were identified and their emission source, transport, and reactivity in the air were elucidated. In the samples, particles in the "soil-derived particles" group were the most abundant, followed by "reacted sea-salts", "reacted CaCO 3-containing particles", "genuine sea-salts", "reacted sea-salts + others", "Fe-containing particles", "anthropogenic organics", (NH 4) 2SO 4, "K-containing particles", and "fly ash". The application of this single-particle analysis, fully utilizing their chemical compositional and morphological data of individual particles, clearly revealed the different characteristics of the six aerosol samples. For samples S3 and S5, which were sampled during two Asian dust storm events, almost all particles were of soil origin that had not experienced chemical modification and that did not entrain sea-salts during their long-range transport. For sample S1, collected at an episodic period of high PM 10 concentration and haze, anthropogenic, secondary, and soil-derived particles emitted from local sources were predominant. For samples S2, S4, and S6, which were collected on average spring days with respect to their PM 10 concentrations, marine originated particles were the most abundant. Sample S2 seems to have been strongly influenced by emissions from the Yellow Sea and Korean peninsula, sample S4 had the minimum anthropogenic influence among the four samples collected in the absence of any Asian dust storm event, and sample S6 seems to have entrained air pollutants that had been

  7. Mass concentration and mineralogical characteristics of aerosol particles collected at Dunhuang during ACE-Asia

    NASA Astrophysics Data System (ADS)

    Shen, Z. X.; Cao, J. J.; Li, X. X.; Okuda, T.; Wang, Y. Q.; Zhang, X. Y.

    2006-03-01

    Measurements were performed in spring 2001 and 2002 to determine the characteristics of soil dust in the Chinese desert region of Dunhuang, one of the ground sites of the Asia-Pacific Regional Aerosol Characterization Experiment (ACE-Asia). The mean mass concentrations of total suspended particle matter during the spring of 2001 and 2002 were 317 mu g m(-3) and 307 mu g m(-3) respectively. Eleven dust storm events were observed with a mean aerosol concentration of 1095 mu g m(-3), while the non-dusty days with calm or weak wind speed had a background aerosol loading of 196 mu g m(-3) on average in the springtime. The main minerals detected in the aerosol samples by X-ray diffraction were illite, kaolinite, chlorite, quartz, feldspar, calcite and dolomite. Gypsum, halite and amphibole were also detected in a few samples. The mineralogical data also show that Asian dust is characterized by a kaolinite to chlorite (K/C) ratio lower than 1 whereas Saharan dust exhibits a K/C ratio larger than 2. Air mass back- trajectory analysis show that three families of pathways are associated with the aerosol particle transport to Dunhuang, but these have similar K/C ratios, which further demonstrates that the mineralogical characteristics of Asian dust are different from African dust.

  8. Impacts of Long-Range Transport of Metals from East Asia in Bulk Aerosols Collected at the Okinawa Archipelago, Japan

    NASA Astrophysics Data System (ADS)

    A, Sotaro; S, Yuka; I, Moriaki; N, Fumiya; H, Daishi; A, Takemitsu; T, Akira

    2010-05-01

    Economy of East Asia has been growing rapidly, and atmospheric aerosols discharged from this region have been transported to Japan. Okinawa island is situated approximately 1500 km south of Tokyo, Japan, 2000 km southeast of Beijing, China, and 1000 km of south Korea. Its location in Asian is well suited for studying long-range transport of air pollutants in East Asia because maritime air mass prevails during summer, while continental air mass dominates during fall, winter, and spring. The maritime air mass data can be seen as background and can be compared with continental air mass which has been affected by anthropogenic activities. Therefore, Okinawa region is suitable area for studying impacts of air pollutants from East Asia. We simultaneously collected bulk aerosol samples by using the same type of high volume air samplers at Cape Hedo Atmospheric Aerosol Monitoring Station (CHAAMS, Okinawa island), Kume island (ca. 160 km south-west of CHAAMS), and Minami-Daitou island (ca. 320 km south-east of CHAAMS). We determined the concentrations of acid-digested metals using atomic absorption spectrometer and inductively-coupled plasma mass spectrometry (ICP-MS). We report and discuss spatial and temporal distribution of metals in the bulk atmospheric aerosols collected at CHAAMS, Kume island and Minami-Daitou island during June, 2008 to June 2009. We also determined 'background' concentration of metals in Okinawa archipelago. We then compare each chemical component among CHAAMS, Kume island and Minami-Daitou island to elucidate the influence of the transport processes and distances from Asian continent on metal concentrations.

  9. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  11. Results from Volcanic Ash Aerosol Collection and Analysis from the Recent Eruptions of Pavlof, Okmok, and Kasatochi Volcanoes, Alaska

    NASA Astrophysics Data System (ADS)

    Rinkleff, P. G.; Cahill, C. F.

    2009-12-01

    Pavlof Volcano, on the Alaska Peninsula SW of Anchorage, Alaska, erupted during Fall 2007; the Aleutian volcanoes, Okmok and Kasatochi, erupted during late Summer 2008. These eruptions sent ash plumes into the North Pacific Ocean, disrupting regional air traffic, and sending ash into nearby communities. The eruptions of Pavlof and Okmok occurred over several weeks and both had waning phases dominated by low level ash emissions. Kasatochi erupted on 7 August 2009 over a period of seven days in large, short, discrete pulses. Fine ash (2.5 - 0.1 micrometer in aerodynamic diameter) from these eruptions was collected using DRUM aerosol impactors. Aerosol samples were analyzed for mass by β-gauge and elemental composition by synchrotron x-ray fluorescence. Aerosols collected during the waning phase of the eruption of Pavlof from 27 August through 2 September 2007 and the eruption of Okmok Volcano 23 July through early August 2008, show strong diurnal cycles in the concentration of ash reaching sampling locations; ash concentrations are highest in the morning and lowest in the early afternoon. Air transport models (HYSPLIT and PUFF) confirm the transport of ash from Pavlof Volcano to Sand Point, Alaska and from Okmok Volcano to Dutch Harbor, Alaska during this interval and show that stable meteorological conditions allowed for the downward mixing of volcanic aerosols to the sampling sites. Although no visible ash fallout was observed during aerosol sampling, these results demonstrate that volcanic ash was present in respirable size fractions downwind of the volcanoes even during periods of low ash emissions. In contrast to Pavlof and Okmok, the Kasatochi eruption was characterized by discrete, strong, short-lived pulses, not sustained low-level ash emissions like the waning phases of the Pavlof and Okmok eruptions. PUFF and HYSPLIT confirm ash from the eruption of Kasatochi was transported to Dutch Harbor. However, the ash collected from Kasatochi eruption pulses

  12. RADIOCARBON MEASUREMENT OF THE BIOGENIC CONTRIBUTION TO SUMMERTIME PM 2.5 AMBIENT AEROSOL IN NASHVILLE, TN

    EPA Science Inventory

    Radiocarbon (14C) measurements performed on PM-2.5 samples collected near Nashville, TN from June 21 to July 13, 1999, showed high levels of modern carbon, ranging from 56 to 80% of the total carbon in the samples. Radiocarbon measurements performed on dichloromethane extracts of...

  13. Use of satellite-based aerosol optical depth and spatial clustering to predict ambient PM2.5 concentrations.

    PubMed

    Lee, Hyung Joo; Coull, Brent A; Bell, Michelle L; Koutrakis, Petros

    2012-10-01

    Satellite-based PM(2.5) monitoring has the potential to complement ground PM(2.5) monitoring networks, especially for regions with sparsely distributed monitors. Satellite remote sensing provides data on aerosol optical depth (AOD), which reflects particle abundance in the atmospheric column. Thus AOD has been used in statistical models to predict ground-level PM(2.5) concentrations. However, previous studies have shown that AOD may not be a strong predictor of PM(2.5) ground levels. Another shortcoming of remote sensing is the large number of non-retrieval days (i.e., days without satellite data available) due to clouds and snow- and ice-cover. In this paper we propose statistical approaches to overcome these two shortcomings, thereby making satellite imagery a viable method to estimate PM(2.5) concentrations. First, we render AOD a robust predictor of PM(2.5) mass concentration by introducing an AOD daily calibration approach through the use of mixed effects model. Second, we develop models that combine AOD and ground monitoring data to predict PM(2.5) concentrations during non-retrieval days. A key feature of this approach is that we develop these prediction models separately for groups of days defined by the observed amount of spatial heterogeneity in concentrations across the study region. Subsequently, these methodologies were applied to examine the spatial and temporal patterns of daily PM(2.5) concentrations for both retrieval days (i.e., days with satellite data available) and non-retrieval days in the New England region of the United States during the period 2000-2008. Overall, for the years 2000-2008, our statistical models predicted surface PM(2.5) concentrations with reasonably high R(2) (0.83) and low percent mean relative error (3.5%). Also the spatial distribution of the estimated PM(2.5) levels in the study domain clearly exhibited densely populated and high traffic areas. The method we have developed demonstrates that remote sensing can have a

  14. Use of satellite-based aerosol optical depth and spatial clustering to predict ambient PM2.5 concentrations.

    PubMed

    Lee, Hyung Joo; Coull, Brent A; Bell, Michelle L; Koutrakis, Petros

    2012-10-01

    Satellite-based PM(2.5) monitoring has the potential to complement ground PM(2.5) monitoring networks, especially for regions with sparsely distributed monitors. Satellite remote sensing provides data on aerosol optical depth (AOD), which reflects particle abundance in the atmospheric column. Thus AOD has been used in statistical models to predict ground-level PM(2.5) concentrations. However, previous studies have shown that AOD may not be a strong predictor of PM(2.5) ground levels. Another shortcoming of remote sensing is the large number of non-retrieval days (i.e., days without satellite data available) due to clouds and snow- and ice-cover. In this paper we propose statistical approaches to overcome these two shortcomings, thereby making satellite imagery a viable method to estimate PM(2.5) concentrations. First, we render AOD a robust predictor of PM(2.5) mass concentration by introducing an AOD daily calibration approach through the use of mixed effects model. Second, we develop models that combine AOD and ground monitoring data to predict PM(2.5) concentrations during non-retrieval days. A key feature of this approach is that we develop these prediction models separately for groups of days defined by the observed amount of spatial heterogeneity in concentrations across the study region. Subsequently, these methodologies were applied to examine the spatial and temporal patterns of daily PM(2.5) concentrations for both retrieval days (i.e., days with satellite data available) and non-retrieval days in the New England region of the United States during the period 2000-2008. Overall, for the years 2000-2008, our statistical models predicted surface PM(2.5) concentrations with reasonably high R(2) (0.83) and low percent mean relative error (3.5%). Also the spatial distribution of the estimated PM(2.5) levels in the study domain clearly exhibited densely populated and high traffic areas. The method we have developed demonstrates that remote sensing can have a

  15. Electron Microscopy Characterization of Aerosols Collected at Mauna Loa Observatory During Asian Dust Storm Event

    EPA Science Inventory

    Atmospheric aerosol particles have a significant influence on global climate due to their ability to absorb and scatter incoming solar radiation. Size, composition, and morphology affect a particle’s radiative properties and these can be characterized by electron microscopy. Lo...

  16. Organosulfate formation in biogenic secondary organic aerosol.

    PubMed

    Surratt, Jason D; Gómez-González, Yadian; Chan, Arthur W H; Vermeylen, Reinhilde; Shahgholi, Mona; Kleindienst, Tadeusz E; Edney, Edward O; Offenberg, John H; Lewandowski, Michael; Jaoui, Mohammed; Maenhaut, Willy; Claeys, Magda; Flagan, Richard C; Seinfeld, John H

    2008-09-11

    Organosulfates of isoprene, alpha-pinene, and beta-pinene have recently been identified in both laboratory-generated and ambient secondary organic aerosol (SOA). In this study, the mechanism and ubiquity of organosulfate formation in biogenic SOA is investigated by a comprehensive series of laboratory photooxidation (i.e., OH-initiated oxidation) and nighttime oxidation (i.e., NO3-initiated oxidation under dark conditions) experiments using nine monoterpenes (alpha-pinene, beta-pinene, d-limonene, l-limonene, alpha-terpinene, gamma-terpinene, terpinolene, Delta(3)-carene, and beta-phellandrene) and three monoterpenes (alpha-pinene, d-limonene, and l-limonene), respectively. Organosulfates were characterized using liquid chromatographic techniques coupled to electrospray ionization combined with both linear ion trap and high-resolution time-of-flight mass spectrometry. Organosulfates are formed only when monoterpenes are oxidized in the presence of acidified sulfate seed aerosol, a result consistent with prior work. Archived laboratory-generated isoprene SOA and ambient filter samples collected from the southeastern U.S. were reexamined for organosulfates. By comparing the tandem mass spectrometric and accurate mass measurements collected for both the laboratory-generated and ambient aerosol, previously uncharacterized ambient organic aerosol components are found to be organosulfates of isoprene, alpha-pinene, beta-pinene, and limonene-like monoterpenes (e.g., myrcene), demonstrating the ubiquity of organosulfate formation in ambient SOA. Several of the organosulfates of isoprene and of the monoterpenes characterized in this study are ambient tracer compounds for the occurrence of biogenic SOA formation under acidic conditions. Furthermore, the nighttime oxidation experiments conducted under highly acidic conditions reveal a viable mechanism for the formation of previously identified nitrooxy organosulfates found in ambient nighttime aerosol samples. We estimate

  17. DEVELOPMENT OF A TAMPER RESISTANT/INDICATING AEROSOL COLLECTION SYSTEM FOR ENVIRONMENTAL SAMPLING AT BULK HANDLING FACILITIES

    SciTech Connect

    Sexton, L.

    2012-06-06

    Environmental sampling has become a key component of International Atomic Energy Agency (IAEA) safeguards approaches since its approval for use in 1996. Environmental sampling supports the IAEA's mission of drawing conclusions concerning the absence of undeclared nuclear material or nuclear activities in a Nation State. Swipe sampling is the most commonly used method for the collection of environmental samples from bulk handling facilities. However, augmenting swipe samples with an air monitoring system, which could continuously draw samples from the environment of bulk handling facilities, could improve the possibility of the detection of undeclared activities. Continuous sampling offers the opportunity to collect airborne materials before they settle onto surfaces which can be decontaminated, taken into existing duct work, filtered by plant ventilation, or escape via alternate pathways (i.e. drains, doors). Researchers at the Savannah River National Laboratory and Oak Ridge National Laboratory have been working to further develop an aerosol collection technology that could be installed at IAEA safeguarded bulk handling facilities. The addition of this technology may reduce the number of IAEA inspector visits required to effectively collect samples. The principal sample collection device is a patented Aerosol Contaminant Extractor (ACE) which utilizes electrostatic precipitation principles to deposit particulates onto selected substrates. Recent work has focused on comparing traditional swipe sampling to samples collected via an ACE system, and incorporating tamper resistant and tamper indicating (TRI) technologies into the ACE system. Development of a TRI-ACE system would allow collection of samples at uranium/plutonium bulk handling facilities in a manner that ensures sample integrity and could be an important addition to the international nuclear safeguards inspector's toolkit. This work was supported by the Next Generation Safeguards Initiative (NGSI), Office

  18. Analyses of Heavy Metal Contents in the Bulk Atmospheric Aerosols Simultaneously Collected at Okinawa Archipelago, Japan by Using X-ray fluorescence spectrometric method (XRF)

    NASA Astrophysics Data System (ADS)

    Oshiro, Y.; ITOH, A.; Azechi, S.; Somada, Y.; Handa, D.; Miyagi, Y.; Arakaki, T.; Tanahara, A.

    2012-12-01

    We studied heavy metal contents of bulk atmospheric aerosols using an X-ray fluorescence spectrometric method (XRF). The XRF method enables us to analyze heavy metal contents in the bulk aerosols rapidly without any chemical pretreatments. We used an energy dispersive X-ray fluorescence spectrometer that is compact and portable. We prepared several different amounts of standard reference materials (referred to "SRM", NIES No.28 of Japanese National Institute of Environmental Studies) on quartz filters for calibration curves in two different methods; 1) water-insoluble materials were collected after dispersing SRM in pure water and filtered with the quartz filters ("wet method"), and 2) SRM was dispersed in air in the plastic container and the aerosols were collected by using the low-volume air sampler ("dry method"). Good linear relationships between X-ray intensity and amount of aerosols on the filter were seen in the following 9 metals; Al, K, Ti, V, Fe, Ni, Rb, Ba, and Pb (with wet method) and 12 metals; K, Ti, Fe, Ni, Rb, Ba, Pb, Sr, Ca, Mn, Zn, and Cu (with dry method). Furthermore, we evaluated quantitative responses of XRF method by comparing with the metal contents determined by inductively coupled plasma mass spectrometry (ICP-MS) and atomic absorption spectrometry (AAS) after acid-digestion. We then used XRF method to determine heavy metal contents in authentic atmospheric aerosols collected in Okinawa islands, Japan. We simultaneously collected bulk aerosol samples by using identical high-volume air samplers at 3 islands; Cape Hedo Atmospheric Aerosol Monitoring Station (CHAAMS, Okinawa island), Kume island (ca. 160 km south-west of CHAAMS), and Minami-Daitou island (ca. 320 km south-east of CHAAMS). We report and discuss spatial and temporal distribution of heavy metals determined by the XRF method in the bulk atmospheric aerosols collected at the three islands during June 2008 to June 2010, and for CHAAMS during June 2008 to October 2012.

  19. Study of aerosols collected in a speleotherapeutic cave situated below Budapest, Hungary

    NASA Astrophysics Data System (ADS)

    Kertész, Zs.; Borbély-Kiss, I.; Hunyadi, I.

    1999-04-01

    The Szemlőhegy-cave is one of the well-known hydrothermal caves of the Rózsadomb area of Budapest, which have been used for speleotherapy of respiratory diseases for years. It is known from the periodically changing airborne radon activity concentration data, that airflow of seasonally reversed direction are formed along the cave passages and fissures due to the temperature difference between the surface and cave air. This means that an intensive interaction takes place between the cave and its environment. The pollution of nearby waters and the urban atmospheric air represents a real danger for these caves below Buda, which recently became the part of the UNESCO World Heritage. The study of cave aerosols should be very important from the point of view of either the control possibilities of the environmental impact or speleotherapy, and probably helps in getting acquainted with the cave-forming processes. In this work we applied our standard aerosol sampling method to the high-humidity environment of the caves, and we studied the elemental composition, size fractionation as well as the spatial distribution and the seasonal variation of cave aerosols. Thanks to the sensitivity of PIXE traces of anthropogenic pollution of the Budapest air are shown in the Szemlőhegy-cave. Measured elemental concentrations remained less than one-tenth the air quality standard valid for the increasingly protected areas.

  20. RAZOR EX Anthrax Air Detection System for detection of Bacillus anthracis spores from aerosol collection samples: collaborative study.

    PubMed

    Hadfield, Ted; Ryan, Valorie; Spaulding, Usha K; Clemens, Kristine M; Ota, Irene M; Brunelle, Sharon L

    2013-01-01

    The RAZOR EX Anthrax Air Detection System was validated in a collaborative study for the detection of Bacillus anthracis in aerosol collection buffer. Phosphate-buffered saline was charged with 1 mg/mL standardized dust to simulate an authentic aerosol collection sample. The dust-charged buffer was spiked with either B. anthracis Ames at 2000 spores/mL or Bacillus cereus at 20 000 spores/mL. Twelve collaborators participated in the study, with four collaborators at each of three sites. Each collaborator tested 12 replicates of B. anthracis in dust-charged buffer and 12 replicates of B. cereus in dust-charged buffer. All samples sets were randomized and blind-coded. All collaborators produced valid data sets (no collaborators displayed systematic errors) and there was only one invalid data point. After unblinding, the analysis revealed a cross-collaborator probability of detection (CPOD) of 1.00 (144 positive results from 144 replicates, 95% confidence interval 0.975-1.00) for the B. anthracis samples and a CPOD of 0.00 (0 positive results from 143 replicates, 95% confidence interval 0.00-0.0262) for the B. cereus samples. These data meet the requirements of AOAC Standard Method Performance Requirement 2010.003, developed by the Stakeholder Panel on Agent Detection Assays. PMID:23767365

  1. Source indicators of biomass burning associated with inorganic salts and carboxylates in dry season ambient aerosol in Chiang Mai Basin, Thailand

    NASA Astrophysics Data System (ADS)

    Tsai, Ying I.; Sopajaree, Khajornsak; Chotruksa, Auranee; Wu, Hsin-Ching; Kuo, Su-Ching

    2013-10-01

    PM10 aerosol was collected between February and April 2010 at an urban site (CMU) and an industrial site (TOT) in Chiang Mai, Thailand, and characteristics and provenance of water-soluble inorganic species, carboxylates, anhydrosugars and sugar alcohols were investigated with particular reference to air quality, framed as episodic or non-episodic pollution. Sulfate, a product of secondary photochemical reactions, was the major inorganic salt in PM10, comprising 25.9% and 22.3% of inorganic species at CMU and TOT, respectively. Acetate was the most abundant monocarboxylate, followed by formate. Oxalate was the dominant dicarboxylate. A high acetate/formate mass ratio indicated that primary traffic-related and biomass-burning emissions contributed to Chiang Mai aerosols during episodic and non-episodic pollution. During episodic pollution carboxylate peaks indicated sourcing from photochemical reactions and/or directly from traffic-related and biomass burning processes and concentrations of specific biomarkers of biomass burning including water-soluble potassium, glutarate, oxalate and levoglucosan dramatically increased. Levoglucosan, the dominant anhydrosugar, was highly associated with water-soluble potassium (r = 0.75-0.79) and accounted for 93.4% and 93.7% of anhydrosugars at CMU and TOT, respectively, during episodic pollution. Moreover, levoglucosan during episodic pollution was 14.2-21.8 times non-episodic lows, showing clearly that emissions from biomass burning are the major cause of PM10 episodic pollution in Chiang Mai. Additionally, the average levoglucosan/mannosan mass ratio during episodic pollution was 14.1-14.9, higher than the 5.73-7.69 during non-episodic pollution, indicating that there was more hardwood burning during episodic pollution. Higher concentrations of glycerol and erythritol during episodic pollution further indicate that biomass burning activities released soil biota from forest and farmland soils.

  2. Carbonaceous aerosols from prescribed burning of a boreal forest ecosystem

    NASA Technical Reports Server (NTRS)

    Mazurek, Monica A.; Cofer, Wesley R., III; Levine, Joel S.

    1991-01-01

    During the boreal forest burn studied, the ambient concentrations for the particle carbon smoke aerosol are highest for the full-fire burn conditions and vary significantly throughout the burn. Collection strategies must accordingly define ranges in the smoke aerosol concentrations produced. While the highest elemental C concentrations are observed during full-fire conditions, the great majority of smoke aerosol particles are in the form of organic C particles irrespective of fire temperature. The formation of organic C light-scattering particles was a significant process in the burn studied.

  3. 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.

  4. a Study of the Origin of Atmospheric Organic Aerosols

    NASA Astrophysics Data System (ADS)

    Hildemann, Lynn Mary

    1990-01-01

    The sources of ambient organic particulate matter in urban areas are investigated through a program of emission source measurements, atmospheric measurements, and mathematical modeling of source/receptor relationships. A dilution sampler intended to collect fine organic aerosol from combustion sources is designed to simulate atmospheric cooling and dilution processes, so that organic vapors which condense under ambient conditions will be collected as particulate matter. This system is used to measure the emissions from a boiler burning distillate oil, a home fireplace, catalyst and noncatalyst automobiles, heavy-duty diesel trucks, natural gas home appliances, and meat cooking operations. Alternate techniques are used to sample the particulate matter emitted from cigarette smoking, a roofing tar pot, paved road dust, brake lining wear, tire wear, and vegetative detritus. The bulk chemical characteristics of the fine aerosol fraction are presented for each source. Over half of the fine aerosol mass emitted from automobiles, wood burning, meat cooking, home appliances, cigarettes, and tar pots is shown to consist of organic compounds. The organic material collected from these sources is analyzed using high-resolution gas chromatography. Using a simple analytical protocol, a quantitative, 50-parameter characterization of the elutable fine organic aerosol emitted from each source type is obtained, which proves to be a unique fingerprint that can be used to distinguish most sources from each other. A mathematical model is used to predict the characteristics of fine ambient organic aerosol in the Los Angeles area that would prevail if the primary organic emissions are transported without chemical reaction. The model is found to track the seasonal variations observed in the ambient aerosol at the three sites studied. Emissions from vehicles and fireplaces are identified as significant sources of solvent-extractable organic aerosol. Differences between the model

  5. DEVELOPMENT AND EVALUATION OF A PROTOTYPE SYSTEM FOR COLLECTING SUB-HOURLY AMBIENT AEROSOL FOR CHEMICAL ANALYSIS. (R825269)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  6. Predicting ambient aerosol thermal-optical reflectance (TOR) measurements from infrared spectra: extending the predictions to different years and different sites

    NASA Astrophysics Data System (ADS)

    Reggente, M.; Dillner, A. M.; Takahama, S.

    2015-11-01

    Organic carbon (OC) and elemental carbon (EC) are major components of atmospheric particulate matter (PM), which has been associated with increased morbidity and mortality, climate change and reduced visibility. Typically OC and EC concentrations are measured using thermal optical methods such as thermal optical reflectance (TOR) from samples collected on quartz filters. In this work, we estimate TOR OC and EC using Fourier transform infrared (FT-IR) absorbance spectra from polytetrafluoroethylene (PTFE or Teflon) filters using partial least square regression (PLSR) calibrated to TOR OC and EC measurements for a wide range of samples. The proposed method can be integrated with analysis of routinely collected PTFE filter samples that, in addition to OC and EC concentrations, can concurrently provide information regarding the composition of the organic aerosol. We have used the FT-IR absorbance spectra and TOR OC and EC concentrations collected in the Interagency Monitoring of PROtected Visual Environment (IMPROVE) network (USA). We used 526 samples collected in 2011 at seven sites to calibrate the models, and more than 2000 samples collected in 2013 at 17 sites to test the models. Samples from six sites are present both in the calibration and test sets. The calibrations produce accurate predictions both for samples collected at the same six sites present in the calibration set (R2=0.97 and R2=0.95 for OC and EC respectively), and for samples from nine of the 11 sites not included in the calibration set (R2=0.96 and R2=0.91 for OC and EC respectively). Samples collected at the other two sites require a different calibration model to achieve accurate predictions. We also propose a method to anticipate the prediction error: we calculate the squared Mahalanobis distance in the feature space (scores determined by PLSR) between new spectra and spectra in the calibration set. The squared Mahalanobis distance provides a crude method for assessing the magnitude of mean error

  7. Predicting ambient aerosol thermal-optical reflectance (TOR) measurements from infrared spectra: extending the predictions to different years and different sites

    NASA Astrophysics Data System (ADS)

    Reggente, Matteo; Dillner, Ann M.; Takahama, Satoshi

    2016-02-01

    Organic carbon (OC) and elemental carbon (EC) are major components of atmospheric particulate matter (PM), which has been associated with increased morbidity and mortality, climate change, and reduced visibility. Typically OC and EC concentrations are measured using thermal-optical methods such as thermal-optical reflectance (TOR) from samples collected on quartz filters. In this work, we estimate TOR OC and EC using Fourier transform infrared (FT-IR) absorbance spectra from polytetrafluoroethylene (PTFE Teflon) filters using partial least square regression (PLSR) calibrated to TOR OC and EC measurements for a wide range of samples. The proposed method can be integrated with analysis of routinely collected PTFE filter samples that, in addition to OC and EC concentrations, can concurrently provide information regarding the functional group composition of the organic aerosol. We have used the FT-IR absorbance spectra and TOR OC and EC concentrations collected in the Interagency Monitoring of PROtected Visual Environments (IMPROVE) network (USA). We used 526 samples collected in 2011 at seven sites to calibrate the models, and more than 2000 samples collected in 2013 at 17 sites to test the models. Samples from six sites are present both in the calibration and test sets. The calibrations produce accurate predictions both for samples collected at the same six sites present in the calibration set (R2 = 0.97 and R2 = 0.95 for OC and EC respectively), and for samples from 9 of the 11 sites not included in the calibration set (R2 = 0.96 and R2 = 0.91 for OC and EC respectively). Samples collected at the other two sites require a different calibration model to achieve accurate predictions. We also propose a method to anticipate the prediction error; we calculate the squared Mahalanobis distance in the feature space (scores determined by PLSR) between new spectra and spectra in the calibration set. The squared Mahalanobis distance provides a crude method for assessing the

  8. Atmospheric Aerosol Chemistry Analyzer: Demonstration of feasibility

    SciTech Connect

    Mroz, E.J.; Olivares, J.; Kok, G.

    1996-04-01

    This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The project objective was to demonstrate the technical feasibility of an Atmospheric Aerosol Chemistry Analyzer (AACA) that will provide a continuous, real-time analysis of the elemental (major, minor and trace) composition of atmospheric aerosols. The AACA concept is based on sampling the atmospheric aerosol through a wet cyclone scrubber that produces an aqueous suspension of the particles. This suspension can then be analyzed for elemental composition by ICP/MS or collected for subsequent analysis by other methods. The key technical challenge was to develop a wet cyclone aerosol sampler suitable for respirable particles found in ambient aerosols. We adapted an ultrasonic nebulizer to a conventional, commercially available, cyclone aerosol sampler and completed collection efficiency tests for the unit, which was shown to efficiently collect particles as small as 0.2 microns. We have completed the necessary basic research and have demonstrated the feasibility of the AACA concept.

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

    NASA Astrophysics Data System (ADS)

    Gao, Yuan; Anderson, James R.

    2001-08-01

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

  10. New aerosol sampler with low wind sensitivity and good filter collection uniformity

    NASA Astrophysics Data System (ADS)

    Kalatoor, Suresh; Grinshpun, Sergey A.; Willeke, Klaus; Baron, Paul

    The overall sampling efficiency of many aerosol samplers is sensitive to wind velocity and direction. In addition, most samplers have internal losses due to gravitational settling, electrostatic interactions, and internal turbulence. A new sampling inlet has been designed to reduce these problems. The flow patterns over the new prototype sampler were visualized in a horizontal wind tunnel. Visualization of the streamlines over the new sampler and limiting-streamline quantitative analysis showed negligible turbulence effects due to the inlet's geometry. The overall sampling efficiency of the prototype sampler was compared to that of a 25 mm closed-face cassette. Uranine was used as the challenge aerosol with particle physical diameters of 13.5, 20 and 30 μm. The wind velocity ranged from 100 to 300 cm s -1. Evaluation of the data showed the new sampler to be less significantly affected by wind direction and magnitude. The particle distribution observed on the sampler's filter was found to be reasonably uniform, an advantage for several types of analyses.

  11. Determinants of the Associations between Ambient Concentrations and Personal Exposures to Ambient PM2.5, NO2, and O3 during DEARS

    EPA Science Inventory

    In this analysis, ambient concentrations and personal exposures to PM2.5, O3, and NO2, air exchange rates, meteorological parameters, and questionnaire survey responses collected during the Detroit Exposure and Aerosol Research Study (DEARS) are used: 1) to evaluate different met...

  12. Intercomparison of elemental concentrations in total and size-fractionated aerosol samples collected during the mace head experiment, April 1991

    NASA Astrophysics Data System (ADS)

    François, Filip; Maenhaut, Willy; Colin, Jean-Louis; Losno, Remi; Schulz, Michael; Stahlschmidt, Thomas; Spokes, Lucinda; Jickells, Timothy

    During an intercomparison field experiment, organized at the Atlantic coast station of Mace Head, Ireland, in April 1991, aerosol samples were collected by four research groups. A variety of samplers was used, combining both high- and low-volume devices, with different types of collection substrates: Hi-Vol Whatman 41 filter holders, single Nuclepore filters and stacked filter units, as well as PIXE cascade impactors. The samples were analyzed by each participating group, using in-house analytical techniques and procedures. The intercomparison of the daily concentrations for 15 elements, measured by two or more participants, revealed a good agreement for the low-volume samplers for the majority of the elements, but also indicated some specific analytical problems, owing to the very low concentrations of the non-sea-salt elements at the sampling site. With the Hi-Vol Whatman 41 filter sampler, on the other hand, much higher results were obtained in particular for the sea-salt and crustal elements. The discrepancy was dependent upon the wind speed and was attributed to a higher collection efficiency of the Hi-Vol sampler for the very coarse particles, as compared to the low-volume devices under high wind speed conditions. The elemental mass size distribution, as derived from parallel cascade impactor samplings by two groups, showed discrepancies in the submicrometer aerosol fraction, which were tentatively attributed to differences in stage cut-off diameters and/or to bounce-off or splintering effects on the quartz impactor slides used by one of the groups. However, the atmospheric concentrations (sums over all stages) were rather similar in the parallel impactor samples and were only slightly lower than those derived from stacked filter unit samples taken in parallel.

  13. Endotoxin in fine (PM 2.5) and coarse (PM 2.5-10) particle mass of ambient aerosols. A temporo-spatial analysis

    NASA Astrophysics Data System (ADS)

    Heinrich, Joachim; Pitz, Mike; Bischof, Wolfgang; Krug, Norbert; Borm, Paul J. A.

    Objectives: We collected fine (PM 2.5) and coarse (PM 2.5-10) particulate matter fractions in two areas ˜80 km apart and measured soluble endotoxin concentrations in both particle fractions. Here we report on temporo-spatial variation of endotoxin content in the collected particles. Methods: Dichotomous Anderson samplers were used to collect 21 weekly samples of PM 2.5 and PM 2.5-10 in both towns from January to June 2002. Each Teflon filter was water extracted and endotoxin was measured by a chromogenic Limulus Amoebocyte Lysate method. Endotoxin concentrations were expressed per mg of fine or mg of coarse mass and per sampled air volume (m 3). Results: For both cities, the mean endotoxin content in PM 2.5 was 1.2 EU mg -1; however the endotoxin content in the coarse fraction was ˜10 times higher compared to the fine mass fractions. Although endotoxin content is highly variable over time, a good correlation was observed between the two town sites for both fine ( r=0.85) and coarse PM ( r=0.88). The fluctuations of weekly endotoxin means were high in both areas suggesting a strong temporal dependence on particle source and composition. The endotoxin content in particles collected during May and June were two to four times higher than concentrations measured during the winter and early spring weeks. Conclusions: Ambient airborne endotoxin concentrations were detected in coarse and fine particle fraction, but 10-fold higher in the coarse PM. The strong seasonality and the week to week fluctuation of endotoxin content in PM indicate different biologic PM properties which might affect results of time series studies on short-term effects as well as in vitro studies and human exposure studies.

  14. Aerosol from Organic Nitrogen in the Southeast United States

    EPA Science Inventory

    Biogenic volatile organic compounds (BVOCs) contribute significantly to organic aerosol in the southeastern United States. During the Southern Oxidant and Aerosol Study (SOAS), a portion of ambient organic aerosol was attributed to isoprene oxidation and organic nitrogen from BVO...

  15. Effect of MODIS Terra radiometric calibration improvements on Collection 6 Deep Blue aerosol products: Validation and Terra/Aqua consistency

    NASA Astrophysics Data System (ADS)

    Sayer, A. M.; Hsu, N. C.; Bettenhausen, C.; Jeong, M.-J.; Meister, G.

    2015-12-01

    The Deep Blue (DB) algorithm's primary data product is midvisible aerosol optical depth (AOD). DB applied to Moderate Resolution Imaging Spectroradiometer (MODIS) measurements provides a data record since early 2000 for MODIS Terra and mid-2002 for MODIS Aqua. In the previous data version (Collection 5, C5), DB production from Terra was halted in 2007 due to sensor degradation; the new Collection 6 (C6) has both improved science algorithms and sensor radiometric calibration. This includes additional calibration corrections developed by the Ocean Biology Processing Group to address MODIS Terra's gain, polarization sensitivity, and detector response versus scan angle, meaning DB can now be applied to the whole Terra record. Through validation with Aerosol Robotic Network (AERONET) data, it is shown that the C6 DB Terra AOD quality is stable throughout the mission to date. Compared to the C5 calibration, in recent years the RMS error compared to AERONET is smaller by ˜0.04 over bright (e.g., desert) and ˜0.01-0.02 over darker (e.g., vegetated) land surfaces, and the fraction of points in agreement with AERONET within expected retrieval uncertainty higher by ˜10% and ˜5%, respectively. Comparisons to the Aqua C6 time series reveal a high level of correspondence between the two MODIS DB data records, with a small positive (Terra-Aqua) average AOD offset <0.01. The analysis demonstrates both the efficacy of the new radiometric calibration efforts and that the C6 MODIS Terra DB AOD data remain stable (to better than 0.01 AOD) throughout the mission to date, suitable for quantitative scientific analyses.

  16. Effect of MODIS Terra Radiometric Calibration Improvements on Collection 6 Deep Blue Aerosol Products: Validation and Terra/Aqua Consistency

    NASA Technical Reports Server (NTRS)

    Sayer, A. M.; Hsu, N. C.; Bettenhausen, C.; Jeong, M.-J.; Meister, G.

    2015-01-01

    The Deep Blue (DB) algorithm's primary data product is midvisible aerosol optical depth (AOD). DB applied to Moderate Resolution Imaging Spectroradiometer (MODIS) measurements provides a data record since early 2000 for MODIS Terra and mid-2002 for MODIS Aqua. In the previous data version (Collection 5, C5), DB production from Terra was halted in 2007 due to sensor degradation; the new Collection 6 (C6) has both improved science algorithms and sensor radiometric calibration. This includes additional calibration corrections developed by the Ocean Biology Processing Group to address MODIS Terra's gain, polarization sensitivity, and detector response versus scan angle, meaning DB can now be applied to the whole Terra record. Through validation with Aerosol Robotic Network (AERONET) data, it is shown that the C6 DB Terra AOD quality is stable throughout the mission to date. Compared to the C5 calibration, in recent years the RMS error compared to AERONET is smaller by approximately 0.04 over bright (e.g., desert) and approximately 0.01-0.02 over darker (e.g., vegetated) land surfaces, and the fraction of points in agreement with AERONET within expected retrieval uncertainty higher by approximately 10% and approximately 5%, respectively. Comparisons to the Aqua C6 time series reveal a high level of correspondence between the two MODIS DB data records, with a small positive (Terra-Aqua) average AOD offset <0.01. The analysis demonstrates both the efficacy of the new radiometric calibration efforts and that the C6 MODIS Terra DB AOD data remain stable (to better than 0.01 AOD) throughout the mission to date, suitable for quantitative scientific analyses.

  17. Assessment of the MODIS-Terra Collection 006 aerosol optical depth data over the greater Mediterranean basin and inter-comparison against MODIS C005 and AERONET

    NASA Astrophysics Data System (ADS)

    Betsikas, Marios; Hatzianastassiou, Nikos; Papadimas, Christos D.; Gkikas, Antonis; Matsoukas, Christos; Sayer, Andrew; Hsu, Christina; Vardavas, Ilias

    2016-04-01

    Aerosols are one of the key factors determining the Earth's solar radiation budget. The aerosol radiative effects are strongly dependent on aerosol optical depth (AOD) which is a good measure of atmospheric aerosol loading. Therefore, understanding better the spatial and temporal patterns of AOD at both global and regional scales is important for more accurate estimations of aerosol radiative effects. Nowadays, improved globally distributed AOD products are available largely based on satellite observations. Currently, one of the most acknowledged accurate AOD dataset is the one derived from measurements of the MODerate resolution Imaging Spectroradiometer (MODIS) instrument onboard the twin Earth Observing System (EOS) Terra and Aqua satellite platforms. The MODIS aerosol retrieval algorithm, which is used to produce AOD data, is continuously improved and updated, leading to releases of successive series, named as Collections. Recently, MODIS Collection 6 (C006) dataset has been made available. Despite their advantages, satellite AOD products have to be assessed through comparisons against ground based AOD products, such as those from AERosol Robotic Network (AERONET). The aim of the present study is to assess the newest MODIS C006 AOD product over the greater Mediterranean basin. The assessment is performed through comparisons of the MODIS-Terra C006 Level-3 AOD data against corresponding data from the previous C005 MODIS dataset, as well as versus AOD data from AERONET stations within the study region. The study period extends from 2001 to 2012 and our comparisons are performed on a monthly basis. Emphasis is given on differences between the MODIS C006 AOD data and corresponding previous C005 data, as to their spatial and temporal, seasonal and inter-annual, patterns. The results show a better agreement of MODIS C006 than C005 AOD data with AERONET, while the C006 data offer a complete spatial coverage of the study region, specifically over the northern African

  18. Recent Rainfall and Aerosol Chemistry From Bermuda

    NASA Astrophysics Data System (ADS)

    Landing, W. M.; Shelley, R.; Kadko, D. C.

    2014-12-01

    This project was devoted to testing the use of Be-7 as a tracer for quantifying trace element fluxes from the atmosphere to the oceans. Rainfall and aerosol samples were collected between June 15, 2011 and July 27, 2013 at the Bermuda Institute of Ocean Sciences (BIOS) located near the eastern end of the island of Bermuda. Collectors were situated near ground level, clear of surrounding vegetation, at a meteorological monitoring station in front of the BIOS laboratory, about 10 m above sea level. This is a Bermuda Air Quality Program site used for ambient air quality monitoring. To quantify the atmospheric deposition of Be-7, plastic buckets were deployed for collection of fallout over ~3 week periods. Wet deposition was collected for trace element analysis using a specially modified "GEOTRACES" N-CON automated wet deposition collector. Aerosol samples were collected with a Tisch TE-5170V-BL high volume aerosol sampler, modified to collect 12 replicate samples on acid-washed 47mm diameter Whatman-41 filters, using procedures identical to those used for the US GEOTRACES aerosol program (Morton et al., 2013). Aerosol and rainfall samples were analyzed for total Na, Mg, Al, P, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Rb, Sr, Zr, Cd, Sb, Ba, La, Ce, Nd, Pb, Th, and U using ICPMS. Confirming earlier data from Bermuda, strong seasonality in rainfall and aerosol loading and chemistry was observed, particularly for aerosol and rainfall Fe concentrations when Saharan dust arrives in July/August with SE trajectories.

  19. A study of the origin of atmospheric organic aerosols

    SciTech Connect

    Hildemann, L.M.

    1990-01-01

    The sources of ambient organic particulate matter in urban areas are investigated through a program of emission source measurements, atmospheric measurements, and mathematical modeling of source/receptor relationships. A dilution sampler intended to collect fine organic aerosol from combustion sources is designed to simulate atmospheric cooling and dilution processes, so that organic vapors which condense under ambient conditions will be collected as particulate matter. This system is used to measure the emissions from a boiler burning distillate oil, a home fireplace, catalyst and noncatalyst automobiles, heavy-duty diesel trucks, natural gas home appliances, and meat-cooking operations. Alternate techniques are used to sample the particulate matter emitted from cigarette smoking, a roofing tar pot, paved road dust, brake lining wear, tire wear, and vegetative detritus. The bulk chemical characteristics of the fine aerosol fraction are presented for each source. Over half of the fine aerosol mass emitted from automobiles, wood burning, meat cooking, home appliances, cigarettes, and tar pots is shown to consist of organic compounds. The organic material collected from these sources is analyzed using high-resolution gas chromatography. Using a simple analytical protocol, a quantitative, 50-parameter characterization of the elutable fine organic aerosol emitted from each source type is obtained, which proves to be a unique fingerprint that can be used to distinguish most sources from each other. A mathematical model is used to predict the characteristics of fine ambient organic aerosol in the Los Angeles area that would prevail if the primary organic emissions are transported without chemical reaction. The model is found to track the seasonal variations observed in the ambient aerosol at the three sites studied.

  20. Unattended Monitoring of HEU Production in Gaseous Centrifuge Enrichment Plants using Automated Aerosol Collection and Laser-based Enrichment Assay

    SciTech Connect

    Anheier, Norman C.; Bushaw, Bruce A.

    2010-08-11

    Nuclear power is enjoying rapid growth as government energy policies and public demand shift toward low carbon energy production. Pivotal to the global nuclear power renaissance is the development and deployment of robust safeguards instrumentation that allows the limited resources of the IAEA to keep pace with the expansion of the nuclear fuel cycle. Undeclared production of highly enriched uranium (HEU) remains a primary proliferation concern for modern gaseous centrifuge enrichment plants (GCEPs), due to their massive separative work unit (SWU) processing power and comparably short cascade equilibrium timescale. The Pacific Northwest National Laboratory is developing an unattended safeguards instrument, combining continuous aerosol particulate collection with uranium isotope assay, to provide timely detection of HEU production within a GCEP. This approach is based on laser vaporization of aerosol particulates, followed by laser spectroscopy to characterize the uranium enrichment level. Our prior investigation demonstrated single-shot detection sensitivity approaching the femtogram range and relative isotope ratio uncertainty better than 10% using gadolinium as a surrogate for uranium. In this paper we present measurement results on standard samples containing traces of depleted, natural, and low enriched uranium, as well as measurements on aerodynamic size uranium particles mixed in background materials (e.g., dust, minerals, soils). Improvements and optimizations in the detection electronics, signal timing, calibration, and laser alignment have lead to significant improvements in detection sensitivity and enrichment accuracy, contributing to an overall reduction in the false alarm probability. The sample substrate media was also found to play a significant role in facilitating laser-induced vaporization and the production of energetic plasma conditions, resulting in ablation optimization and further improvements in the isotope abundance sensitivity.

  1. Chemical analysis of refractory stratospheric aerosol particles collected within the arctic vortex and inside polar stratospheric clouds

    NASA Astrophysics Data System (ADS)

    Ebert, Martin; Weigel, Ralf; Kandler, Konrad; Günther, Gebhard; Molleker, Sergej; Grooß, Jens-Uwe; Vogel, Bärbel; Weinbruch, Stephan; Borrmann, Stephan

    2016-07-01

    Stratospheric aerosol particles with diameters larger than about 10 nm were collected within the arctic vortex during two polar flight campaigns: RECONCILE in winter 2010 and ESSenCe in winter 2011. Impactors were installed on board the aircraft M-55 Geophysica, which was operated from Kiruna, Sweden. Flights were performed at a height of up to 21 km and some of the particle samples were taken within distinct polar stratospheric clouds (PSCs). The chemical composition, size and morphology of refractory particles were analyzed by scanning electron microscopy and energy-dispersive X-ray microanalysis. During ESSenCe no refractory particles with diameters above 500 nm were sampled. In total 116 small silicate, Fe-rich, Pb-rich and aluminum oxide spheres were found. In contrast to ESSenCe in early winter, during the late-winter RECONCILE mission the air masses were subsiding inside the Arctic winter vortex from the upper stratosphere and mesosphere, thus initializing a transport of refractory aerosol particles into the lower stratosphere. During RECONCILE, 759 refractory particles with diameters above 500 nm were found consisting of silicates, silicate / carbon mixtures, Fe-rich particles, Ca-rich particles and complex metal mixtures. In the size range below 500 nm the presence of soot was also proven. While the data base is still sparse, the general tendency of a lower abundance of refractory particles during PSC events compared to non-PSC situations was observed. The detection of large refractory particles in the stratosphere, as well as the experimental finding that these particles were not observed in the particle samples (upper size limit ˜ 5 µm) taken during PSC events, strengthens the hypothesis that such particles are present in the lower polar stratosphere in late winter and have provided a surface for heterogeneous nucleation during PSC formation.

  2. AUTORAMP - an automatic unit for unattended aerosol collection, gamma-ray analysis and data transmission from remote locations

    SciTech Connect

    Latner, N.; Sanderson, C.G.; Negro, V.C.

    1997-12-31

    The Environmental Measurements Laboratory has designed, developed and field tested a fully automated and completely unattended multisample, surface-air monitoring system. This system, AUTORAMP, collects large-volume aerosol samples on discrete pleated cartridge filters, measures these samples in a near ideal geometry with a refrigerator-cooled Germanium gamma-ray detector, and immediately transmits the resulting spectra through a telephone/modem connection or a satellite link. Using a sample tray loaded with 31 filters, the system will allow for more than six months of unattended operation with weekly sampling, or one month of daily sampling. Remote control of all operating functions is possible through the communications link. For a 24-h collection, at 12,000 m{sup 3} d{sup -1} and a 18-h gamma-ray count, this system can detect as little as 2.7 {mu}Bq m{sup -3} of the short-lived {sup 140}Ba and 5.4 {mu}Bq m{sup -3} of {sup 137}Cs.

  3. Mass spectroscopy of single aerosols from field measurements

    SciTech Connect

    Thomson, D.S.; Murphy, D.M.

    1995-12-31

    We are developing an aircraft instrument for the chemical analysis of individual ambient aerosols in real time. In order to test the laboratory version of this instrument, we participated in a field campaign near the continental divide in Colorado in September, 1993. During this campaign, over 5000 mass spectra of ambient aerosols were collected. Analysis of the negative ion spectra shows that sulfate was the most commonly seen component of smaller particles, while nitrate was more common in larger particles. Organic compounds are present in most particles, and we believe we can distinguish inorganic carbon in some particles. Although numerous distinct classes of particles were observed, indicating external mixtures, almost all of these particle types were themselves mixtures of several compounds. Finally, we note that although the field site experienced distinct polluted and unpolluted episodes, aerosol composition did not correlate with gas phase chemistry.

  4. Experimental determination of the partitioning coefficient and volatility of important BVOC oxidation products using the Aerosol Collection Module (ACM) coupled to a PTR-ToF-MS

    NASA Astrophysics Data System (ADS)

    Gkatzelis, G.; Hohaus, T.; Tillmann, R.; Schmitt, S. H.; Yu, Z.; Schlag, P.; Wegener, R.; Kaminski, M.; Kiendler-Scharr, A.

    2015-12-01

    Atmospheric aerosol can alter the Earth's radiative budget and global climate but can also affect human health. A dominant contributor to the submicrometer particulate matter (PM) is organic aerosol (OA). OA can be either directly emitted through e.g. combustion processes (primary OA) or formed through the oxidation of organic gases (secondary organic aerosol, SOA). A detailed understanding of SOA formation is of importance as it constitutes a major contribution to the total OA. The partitioning between the gas and particle phase as well as the volatility of individual components of SOA is yet poorly understood adding uncertainties and thus complicating climate modelling. In this work, a new experimental methodology was used for compound-specific analysis of organic aerosol. The Aerosol Collection Module (ACM) is a newly developed instrument that deploys an aerodynamic lens to separate the gas and particle phase of an aerosol. The particle phase is directed to a cooled sampling surface. After collection particles are thermally desorbed and transferred to a detector for further analysis. In the present work, the ACM was coupled to a Proton Transfer Reaction-Time of Flight-Mass Spectrometer (PTR-ToF-MS) to detect and quantify organic compounds partitioning between the gas and particle phase. This experimental approach was used in a set of experiments at the atmosphere simulation chamber SAPHIR to investigate SOA formation. Ozone oxidation with subsequent photochemical aging of β-pinene, limonene and real plant emissions from Pinus sylvestris (Scots pine) were studied. Simultaneous measurement of the gas and particle phase using the ACM-PTR-ToF-MS allows to report partitioning coefficients of important BVOC oxidation products. Additionally, volatility trends and changes of the SOA with photochemical aging are investigated and compared for all systems studied.

  5. Contrasting online MSn spectra of organic acids in ambient aerosol from the boreal forest at Hyytiälä, Finland and from the mixed forest at the Taunus observatory, Germany

    NASA Astrophysics Data System (ADS)

    Vogel, Alexander L.; Äijälä, Mikko; Ehn, Mikael; Junninen, Heikki; Petäjä, Tuukka; Worsnop, Douglas R.; Kulmala, Markku; Williams, Jonathan; Schneider, Johannes; Hoffmann, Thorsten

    2013-04-01

    Emission of biogenic volatile organic compounds (BVOCs) by the vegetation and subsequent atmospheric oxidation leads to the formation of secondary organic aerosol (SOA). Therefore, forests are a main source of aerosols which have significant impact on the earth's climate.[1] The oxidation of BVOCs results in a variety of mostly unidentified organic species in trace level concentrations, which partition between gas- and particle-phase. Organic acids are of particular importance for the particle-phase fraction, since the higher oxidation state and molecular mass, compared to the corresponding precursors, is accompanied by a much lower volatility. Until now, only limited instrumentation exists for the simultaneous online analysis of organic acids in gas- and particle-phase. Here we show the first field application of an Atmospheric Pressure Chemical Ionization Ion Trap Mass Spectrometer (APCI-IT-MS) in combination with a miniature Versatile Aerosol Concentration Enrichment System (mVACES) for measuring organic acids in gas- and particle-phase[2]. The benefits of the online APCI-IT-MS are soft ionization with low fragmentation, high time resolution and less sampling artifacts than in the common procedure of taking filter samples, extraction and subsequent detection with LC-MS. Furthermore, the capability to perform online MSn of isolated m/z ratios from ambient and laboratory generated aerosol leads to an improved understanding of the composition of secondary organic aerosol. The here described measurements were conducted during the HUMPPA-COPEC 2010 campaign at Hyytiälä, Finland and during the INUIT campaign 2012 on Mt. Kleiner Feldberg, Germany. By merging APCI-IT-MS data with data from the Aerodyné C-ToF-AMS, it can be observed that the gas- to particle-partitioning of organic acids strongly depends on the fraction of aerosol which is organic matter, as it is predicted by a partitioning model[3]. High observed gas-phase concentrations of organic acids at Hyyti

  6. Culturability of Bacillus spores on aerosol collection filters exposed to airborne combustion products of Al, Mg, and B·Ti.

    PubMed

    Adhikari, Atin; Yermakov, Michael; Indugula, Reshmi; Reponen, Tiina; Driks, Adam; Grinshpun, Sergey A

    2016-05-01

    Destruction of bioweapon facilities due to explosion or fire could aerosolize highly pathogenic microorganisms. The post-event air quality assessment is conducted through air sampling. A bioaerosol sample (often collected on a filter for further culture-based analysis) also contains combustion products, which may influence the microbial culturability and, thus, impact the outcome. We have examined the interaction between spores deposited on collection filters using two simulants of Bacillus anthracis [B. thuringiensis (Bt) and B. atrophaeus (referred to as BG)] and incoming combustion products of Al as well as Mg and B·Ti (common ingredient of metalized explosives). Spores extracted from Teflon, polycarbonate, mixed cellulose ester (MCE), and gelatin filters (most common filter media for bioaerosol sampling), which were exposed to combustion products during a short-term sampling, were analyzed by cultivation. Surprisingly, we observed that aluminum combustion products enhanced the culturability of Bt (but not BG) spores on Teflon filters increasing the culturable count by more than an order of magnitude. Testing polycarbonate and MCE filter materials also revealed a moderate increase of culturability although gelatin did not. No effect was observed with either of the two species interacting on either filter media with products originated by combustion of Mg and B·Ti. Sample contamination, spore agglomeration, effect of a filter material on the spore survival, changes in the spore wall ultrastructure and germination, as well as other factors were explored to interpret the findings. The study raises a question about the reliability of certain filter materials for collecting airborne bio-threat agents in combustion environments. PMID:26914458

  7. Culturability of Bacillus spores on aerosol collection filters exposed to airborne combustion products of Al, Mg, and B·Ti.

    PubMed

    Adhikari, Atin; Yermakov, Michael; Indugula, Reshmi; Reponen, Tiina; Driks, Adam; Grinshpun, Sergey A

    2016-05-01

    Destruction of bioweapon facilities due to explosion or fire could aerosolize highly pathogenic microorganisms. The post-event air quality assessment is conducted through air sampling. A bioaerosol sample (often collected on a filter for further culture-based analysis) also contains combustion products, which may influence the microbial culturability and, thus, impact the outcome. We have examined the interaction between spores deposited on collection filters using two simulants of Bacillus anthracis [B. thuringiensis (Bt) and B. atrophaeus (referred to as BG)] and incoming combustion products of Al as well as Mg and B·Ti (common ingredient of metalized explosives). Spores extracted from Teflon, polycarbonate, mixed cellulose ester (MCE), and gelatin filters (most common filter media for bioaerosol sampling), which were exposed to combustion products during a short-term sampling, were analyzed by cultivation. Surprisingly, we observed that aluminum combustion products enhanced the culturability of Bt (but not BG) spores on Teflon filters increasing the culturable count by more than an order of magnitude. Testing polycarbonate and MCE filter materials also revealed a moderate increase of culturability although gelatin did not. No effect was observed with either of the two species interacting on either filter media with products originated by combustion of Mg and B·Ti. Sample contamination, spore agglomeration, effect of a filter material on the spore survival, changes in the spore wall ultrastructure and germination, as well as other factors were explored to interpret the findings. The study raises a question about the reliability of certain filter materials for collecting airborne bio-threat agents in combustion environments.

  8. Spectra Aerosol Light Scattering and Absorption for Laboratory and Urban Aerosol

    NASA Astrophysics Data System (ADS)

    Gyawali, Madhu S.

    Atmospheric aerosols considerably influence the climate, reduce visibility, and cause problems in human health. Aerosol light absorption and scattering are the important factors in the radiation transfer models. However, these properties are associated with large uncertainties in climate modeling. In addition, atmospheric aerosols widely vary in composition and size; their optical properties are highly wavelength dependent. This work presents the spectral dependence of aerosol light absorption and scattering throughout the ultraviolet to near-infrared regions. Data were collected in Reno, NV from 2008 to 2010. Also presented in this study are the aerosol optical and physical properties during carbonaceous aerosols and radiative effects study (CARES) conducted in Sacramento area during 2010. Measurements were made using photoacoustic instruments (PA), including a novel UV 355 nm PA of our design and manufacture. Comparative analyses are presented for three main categories: (1) aerosols produced by wildfires and traffic emissions, (2) laboratory-generated and wintertime ambient urban aerosols, and (3) urban plume and biogenic emissions. In these categories, key questions regarding the light absorption by secondary organic aerosols (SOA), so-called brown carbon (BrC), and black carbon (BC) will be discussed. An effort is made to model the emission and aging of urban and biomass burning aerosol by applying shell-core calculations. Multispectral PA measurements of aerosols light absorption and scattering coefficients were used to calculate the Angstrom exponent of absorption (AEA) and single scattering albedo (SSA). The AEA and SSA values were analyzed to differentiate the aerosol sources. The California wildfire aerosols exhibited strong wavelength dependence of aerosol light absorption with AEA as lambda -1 for 405 and 870 nm, in contrast to the relatively weak wavelength dependence of traffic emissions aerosols for which AEA varied approximately as lambda-1. By using

  9. Examining the relationship between atmospheric aerosols and light extinction at Mount Rainier and North Cascades National Parks

    NASA Astrophysics Data System (ADS)

    Malm, W. C.; Gebhart, K. A.; Molenar, J.; Cahill, T.; Eldred, R.; Huffman, D.

    During the summer of 1990, the National Park Service carried out a study in the state of Washington called the Pacific Northwest Regional Visibility Experiment using Natural Tracers (PREVENT). The goal of the study was to apportion atmospheric aerosols to scattering and extinction and to source types at Mount Rainier and North Cascades National Parks. The study was designed to collect all necessary emissions, meteorology, ambient concentrations, and atmospheric optical data necessary to support a variety of source attribution techniques. This paper will report on the apportionment of various aerosol species to measured fine mass concentrations and ambient scattering coefficients. One highlight of this study was the near-ambient measurement of atmospheric scattering with a modified integrating nephelometer. It is therefore possible to explore the relationship between hygroscopic aerosols and scattering in the ambient atmosphere.

  10. Trace elements in daily collected aerosols in Al-Hashimya, central Jordan

    NASA Astrophysics Data System (ADS)

    Al-Momani, Idrees F.; Daradkeh, A. S.; Haj-Hussein, Amin T.; Yousef, Yaser A.; Jaradat, Q. M.; Momani, K. A.

    2005-01-01

    Coarse (>2.2 μm) and fine (<2.2 μm) atmospheric particulate material samples were collected from an urban area (Al-Hashimya, Jordan), from August 2000 to August 2001 using a "GENT" stack filter unit (SFU). Collected samples were analyzed for 19 elements using inductively coupled plasma mass spectrometry (ICP-MS). The crustal elements exhibit atmospheric concentrations that are comparable to those in urban and industrial areas. The anthropogenic elements, on the other hand, are clearly less abundant in Al-Hashimya than in other industrial regions. Results indicated that, elements of crustal origin are associated with the coarse particles, while elements of anthropogenic origins are more associated with fine particles. Concentrations of crustal-derived elements were higher in summer and those of anthropogenic elements were higher in winter. Crustal enrichment factor calculations showed that concentrations of Pb, Zn, Cd, Sb and Ag are highly enriched and of As, Cu, Co, Ca and Ni are moderately enriched. Factor analysis calculations permitted the identification of four source groups for the fine fraction, namely oil combustion, crustal and urban dust, smelting industries and motor vehicles.

  11. Comparison of physical and chemical properties of ambient aerosols during the 2009 haze and non-haze periods in Southeast Asia.

    PubMed

    Xu, Jingsha; Tai, Xuhong; Betha, Raghu; He, Jun; Balasubramanian, Rajasekhar

    2015-10-01

    Recurrent smoke-haze episodes that occur in Southeast Asia (SEA) are of much concern because of their environmental and health impacts. These haze episodes are mainly caused by uncontrolled biomass and peat burning in Indonesia. Airborne particulate matter (PM) samples were collected in the southwest coast of Singapore from 16 August to 9 November in 2009 to assess the impact of smoke-haze episodes on the air quality due to the long-range transport of biomass and peat burning emissions. The physical and chemical characteristics of PM were investigated during pre-haze, smoke-haze, and post-haze periods. Days with PM2.5 mass concentrations of ≥35 μg m(-3) were considered as smoke-haze events. Using this criterion, out of the total 82 sampling days, nine smoke-haze events were identified. The origin of air masses during smoke-haze episodes was studied on the basis of HYSPLIT backward air trajectory analysis for 4 days. In terms of the physical properties of PM, higher particle surface area concentrations and particle gravimetric mass concentrations were observed during the smoke-haze period, but there was no consistent pattern for particle number concentrations during the haze period as compared to the non-haze period except that there was a significant increase at about 08:00, which could be attributed to the entrainment of PM from aloft after the breakdown of the nocturnal inversion layer. As for the chemical characteristics of PM, among the six key inorganic water-soluble ions (Cl(-), NO3(-), nss-SO4(2-), Na(+), NH4(+), and nss-K(+)) measured in this study, NO3(-), nss-SO4(2-), and NH4(+) showed a significant increase in their concentrations during the smoke-haze period together with nss-K(+). These observations suggest that the increased atmospheric loading of PM with higher surface area and increased concentrations of optically active secondary inorganic aerosols [(NH4)2SO4 or NH4HSO4 and NH4NO3] resulted in the atmospheric visibility reduction in SEA due to

  12. FEASIBILITY OF THE AEROSOL-TO-LIQUID PARTICLE EXTRACTION SYSTEM (ALPES) FOR COLLECTION OF VIABLE FRANCISELLA SP.

    SciTech Connect

    Heitkamp, M

    2006-08-07

    Several Biowatch monitoring sites in the Houston area have tested positive for Francisella tularensis and there is a need to determine whether natural occurring Francisella-related microorganism(s) may be responsible for these observed positive reactions. The collection, culturing and characterization of Francisella-related natural microorganisms will provide the knowledge base to improve the future selectivity of Biowatch monitoring for Francisella. The aerosol-to-liquid particle extraction system (ALPES) is a high-efficiency, dual mechanism collection system that utilizes a liquid collection medium for capture of airborne microorganisms. Since the viability of microorganisms is preserved better in liquid medium than on air filters, this project was undertaken to determine whether Francisella philomiragia and Francisella tularensis LVS maintain acceptable viability in the continuous liquid recirculation, high direct current voltage and residual ozone concentrations which occur during ALPES operation. Throughout a series of preliminary trial runs with representative gram-negative and gram-positive microorganisms, several design modifications and improvements to the ALPES optimized liquid handling, electrical stability, sampling and overall performance for biological sampling. Initial testing with Francisella philomiragia showed viability was preserved better in PBS buffer than HBSS buffer. Trial runs at starting cell concentrations of 1.8 x 10{sup 6} and 2.5 x 10{sup 4} CFU/L showed less than a 1-log decrease in viability for F. philomiragia after 24 h in the ALPES. Francisella tularensis LVS (live vaccine strain) was used as a surrogate for virulent F. tularensis in ALPES trial runs conducted at starting cell concentrations of 10{sup 4}, 10{sup 5} and 10{sup 6} CFU/L. F. tularensis LVS was slow-growing and required highly selective growth media to prevent overgrowth by collected airborne microorganisms. In addition, one ALPES unit intake was HEPA filtered during

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  14. Analysis of Atmospheric Aerosols Collected in an Urban Area in Upstate NY Using Proton Induced X-ray Emission (PIXE) Spectroscopy

    NASA Astrophysics Data System (ADS)

    Smith, Jeremy; Ali, Salina; Nadareski, Benjamin; Safiq, Alexandrea; Yoskowitz, Joshua; Labrake, Scott; Vineyard, Michael

    2013-10-01

    We examined atmospheric aerosol samples collected in Schenectady NY for evidence of pollution. We collected aerosol samples using a nine stage cascade impactor which distributes the particulate matter by aerodynamic size onto 7.5 μm Kapton foils. We then used a 1MV electrostatic Pelletron accelerator to produce a 2.2 MeV proton beam to hit the impacted foils. X-ray intensity versus energy spectra were collected using an Amptek x-ray detector where the x-rays are produced from the proton beam interacting with the sample. This is called PIXE. The elemental composition and concentrations of the elements present in the aerosol samples were determined using a software package called GUPIX. We have found elements ranging from Al to Pb and in particular have found significant amounts of Pb and Br on some of our impacted foils, with a Br/Pb ratio of 0.6 +/- 0.2 which agrees with previous studies. This result suggests the presence of leaded aviation fuel perhaps due to the proximity of the collection site to a small airport with a significant amount of general aviation traffic. Union College.

  15. Comparative In Vitro Toxicity Profile of Electronic and Tobacco Cigarettes, Smokeless Tobacco and Nicotine Replacement Therapy Products: E-Liquids, Extracts and Collected Aerosols

    PubMed Central

    Misra, Manoj; Leverette, Robert D.; Cooper, Bethany T.; Bennett, Melanee B.; Brown, Steven E.

    2014-01-01

    The use of electronic cigarettes (e-cigs) continues to increase worldwide in parallel with accumulating information on their potential toxicity and safety. In this study, an in vitro battery of established assays was used to examine the cytotoxicity, mutagenicity, genotoxicity and inflammatory responses of certain commercial e-cigs and compared to tobacco burning cigarettes, smokeless tobacco (SLT) products and a nicotine replacement therapy (NRT) product. The toxicity evaluation was performed on e-liquids and pad-collected aerosols of e-cigs, pad-collected smoke condensates of tobacco cigarettes and extracts of SLT and NRT products. In all assays, exposures with e-cig liquids and collected aerosols, at the doses tested, showed no significant activity when compared to tobacco burning cigarettes. Results for the e-cigs, with and without nicotine in two evaluated flavor variants, were very similar in all assays, indicating that the presence of nicotine and flavors, at the levels tested, did not induce any cytotoxic, genotoxic or inflammatory effects. The present findings indicate that neither the e-cig liquids and collected aerosols, nor the extracts of the SLT and NRT products produce any meaningful toxic effects in four widely-applied in vitro test systems, in which the conventional cigarette smoke preparations, at comparable exposures, are markedly cytotoxic and genotoxic. PMID:25361047

  16. Define and Quantify the Physics of Air Flow, Pressure Drop and Aerosol Collection in Nuclear Grade HEPA Filters

    SciTech Connect

    Moore, Murray E.

    2015-02-23

    Objective: Develop a set of peer-review and verified analytical methods to adjust HEPA filter performance to different flow rates, temperatures and altitudes. Experimental testing will measure HEPA filter flow rate, pressure drop and efficiency to verify the analytical approach. Nuclear facilities utilize HEPA (High Efficiency Particulate Air) filters to purify air flow for workspace ventilation. However, the ASME AG-1 technical standard (Code on Nuclear Air and Gas Treatment) does not adequately describe air flow measurement units for HEPA filter systems. Specifically, the AG-1 standard does not differentiate between volumetric air flow in ACFM (actual cubic feet per minute)compared to mass flow measured in SCFM (standard cubic feet per minute). More importantly, the AG-1 standard has an overall deficiency for using HEPA filter devices at different air flow rates, temperatures, and altitudes. Technical Approach: The collection efficiency and pressure drops of 18 different HEPA filters will be measured over a range of flow rates, temperatures and altitudes. The experimental results will be compared to analytical scoping calculations. Three manufacturers have allocated six HEPA filters each for this effort. The 18 filters will be tested at two different flow rates, two different temperatures and two different altitudes. The 36 total tests will be conducted at two different facilities: the ATI Test facilities (Baltimore MD) and the Los Alamos National Laboratory (Los Alamos NM). The Radiation Protection RP-SVS group at Los Alamos has an aerosol wind tunnel that was originally designed to evaluate small air samplers. In 2010, modifications were started to convert the wind tunnel for HEPA filter testing. (Extensive changes were necessary for the required aerosol generators, HEPA test fixtures, temperature control devices and measurement capabilities.) To this date, none of these modification activities have been funded through a specific DOE or NNSA program. This is

  17. Genotypic and phenotypic characterization of aerosolized bacteria collected from African dust events

    DOE PAGESBeta

    Wilson, Christina A.; Brigmon, Robin L.; Yeager, Chris; Smith, Garriet W.; Polson, Shawn W.

    2013-07-31

    Twenty-one bacteria were isolated and characterized from air samples collected in Africa and the Caribbean by the United States Geological Survey (USGS). Isolates were selected based on preliminary characterization as possible pathogens. Identification of the bacterial isolates was 25 achieved using 16S rRNA gene sequence analysis, fatty acid methyl esters (FAMEs) profiling, the BIOLOG Microlog® System (carbon substrate assay), and repetitive extragenic palindromic (REP)-PCR analysis. The majority of isolates (18/21) were identified as species of the genus Bacillus. Three isolates were classified within the Bacillus cereus senso lato group, which includes Bacillus anthracis, Bacillus thuringiensis, and Bacillus cereus strains. Onemore » isolate was identified as a Staphylococcus sp., 30 most closely related to species (i.e Staphylococcus kloosii, Staphylococcus warneri) that are commonly associated with human or animal skin, but can also act as opportunistic pathogen. Another isolate was tentatively identified as Tsukamurella inchonensis, a known respiratory pathogen, and was resistant to the ten antibiotics tested including vancomycin.« less

  18. Genotypic and phenotypic characterization of aerosolized bacteria collected from African dust events

    SciTech Connect

    Wilson, Christina A.; Brigmon, Robin L.; Yeager, Chris; Smith, Garriet W.; Polson, Shawn W.

    2013-07-31

    Twenty-one bacteria were isolated and characterized from air samples collected in Africa and the Caribbean by the United States Geological Survey (USGS). Isolates were selected based on preliminary characterization as possible pathogens. Identification of the bacterial isolates was 25 achieved using 16S rRNA gene sequence analysis, fatty acid methyl esters (FAMEs) profiling, the BIOLOG Microlog® System (carbon substrate assay), and repetitive extragenic palindromic (REP)-PCR analysis. The majority of isolates (18/21) were identified as species of the genus Bacillus. Three isolates were classified within the Bacillus cereus senso lato group, which includes Bacillus anthracis, Bacillus thuringiensis, and Bacillus cereus strains. One isolate was identified as a Staphylococcus sp., 30 most closely related to species (i.e Staphylococcus kloosii, Staphylococcus warneri) that are commonly associated with human or animal skin, but can also act as opportunistic pathogen. Another isolate was tentatively identified as Tsukamurella inchonensis, a known respiratory pathogen, and was resistant to the ten antibiotics tested including vancomycin.

  19. SOURCE APPORTIONMENT OF PHOENIX PM2.5 AEROSOL WITH THE UNMIX RECEPTOR MODEL

    EPA Science Inventory

    The multivariate receptor model Unmix has been used to analyze a 3-yr PM2.5 ambient aerosol data set collected in Phoenix, AZ, beginning in 1995. The analysis generated source profiles and overall percentage source contribution estimates (SCE) for five source categories: ga...

  20. ß-CARYOPHYLLINIC ACID: AN ATMOSPHERIC TRACER FOR ß-CARYOPHYLLENE SECONDARY ORGANIC AEROSOL

    EPA Science Inventory

    The chemical compositions of ambient PM2.5 samples, collected in Research Triangle Park, North Carolina, USA, and a sample of secondary organic aerosol, formed by irradiating a mixture of the sesquiterpene, ß-caryophyllene, and oxides of nitrogen in a smog chamber, wer...

  1. A COMPARATIVE ASSESSMENT OF BOISE, IDAHO, AMBIENT AIR FINE PARTICLE SAMPLES USING THE PLATE AND MICROSUSPENSION SALMONELLA MUTAGENICITY ASSAYS

    EPA Science Inventory

    The primary objective of this study is to characterize the genotoxic potential of the ambient air aerosols collected within an air shed impacted primarily by wood smoke and automotive emissions. The study also examines the relative merits of a microsuspension assay and the standa...

  2. Improvement in understanding the deposition of ambient dust particles on ECAM (environmental continuous air monitor) filters, reduction of the alpha-particle interference of radon progeny and other radioactive aerosols in different particle size ranges on filters, and development of ECAMs with increased sensitivity under dusty outdoor conditions.

    SciTech Connect

    Schery, Stephen D., Wasiolek, Piotr; Rodgers, John

    1999-06-01

    Improvement in understanding the deposition of ambient dust particles on ECAM (environmental continuous air monitor) filters, reduction of the alpha-particle interference of radon progeny and other radioactive aerosols in different particle size ranges on filters, and development of ECAMs with increased sensitivity under dusty outdoor conditions.

  3. Climatology and trends of aerosol optical depth over the Mediterranean basin during the last 12years (2002-2014) based on Collection 006 MODIS-Aqua data.

    PubMed

    Floutsi, A A; Korras-Carraca, M B; Matsoukas, C; Hatzianastassiou, N; Biskos, G

    2016-05-01

    The Mediterranean basin is a region of particular interest for studying atmospheric aerosols due to the large variety of air masses it receives, and its sensitivity to climate change. In this study we use the newest collection (C006) of aerosol optical depth from MODIS-Aqua, from which we also derived the fine-mode fraction and Ångström exponent over the last 12years (i.e., from 2002 to 2014), providing the longest analyzed dataset for this region. The long-term regional optical depth average is 0.20±0.05, with the indicated uncertainty reflecting the inter-annual variability. Overall, the aerosol optical depth exhibits a south-to-north decreasing gradient and an average decreasing trend of 0.0030 per year (19% total decrease over the study period). The correlation between the reported AOD observations with measurements from the ground AERONET stations is high (R=0.76-0.80 depending on the wavelength), with the MODIS-Aqua data being slightly overestimated. Both fine-fraction and Ångström exponent data highlight the dominance of anthropogenic aerosols over the northern, and of desert aerosols over the southern part of the region. Clear intrusions of desert dust over the Eastern Mediterranean are observed principally in spring, and in some cases in winter. Dust intrusions dominate the Western Mediterranean in the summer (and sometimes in autumn), whereas anthropogenic aerosols dominate the sub-region of the Black Sea in all seasons but especially during summer. Fine-mode optical depth is found to decrease over almost all areas of the study region during the 12-year period, marking the decreasing contribution of anthropogenic particulate matter emissions over the study area. Coarse-mode aerosol load also exhibits an overall decreasing trend. However, its decrease is smaller than that of fine aerosols and not as uniformly distributed, underlining that the overall decrease in the region arises mainly from reduced anthropogenic emissions. PMID:26878641

  4. Unraveling the Complexity of Atmospheric Aerosol: Insights from Ultrahigh Resolution Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Mazzoleni, Lynn R.; Zhao, Yunzhu; Samburova, Vera; Gannet Hallar, A.; Lowenthal, Douglas

    2016-04-01

    Atmospheric aerosol organic matter (AOM) is a complex mixture of thousands of organic compounds, which may have significant influence on the climate-relevant properties of atmospheric aerosols. An improved understanding of the molecular composition of AOM is needed to evaluate the effect of aerosol composition upon aerosol physical properties. Products of gas, aqueous and particle phase reactions contribute to the aerosol organic mass. Thus, ambient aerosols carry a complex array of AOM components with variable chemical signatures depending upon its origin and aerosol life-cycle processes. In this work, ultrahigh-resolution Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS) was used to characterize ambient aerosol AOM collected at the Storm Peak Laboratory (3210 m a.s.l.) near Steamboat Springs, CO. Thousands of molecular formulas were assigned in the mass range of m/z 100-800 after negative-ion electrospray ionization. Using multivariate statistical analysis, correlations between the site meteorological conditions and specific molecular compositions were identified. For example, days with strong UV radiation and high temperature were found to contain large numbers of biogenic SOA molecular formulas. Similarly, days with high relative humidity and high sulfate concentrations were found to contain many sulfur-containing compounds, suggesting their aqueous phase formation.

  5. An assessment of the performance of Monitor for AeRosols and GAses in ambient air (MARGA): a semi-continuous method for soluble compounds

    EPA Science Inventory

    Ambient air monitoring as part of the U.S. Environmental Protection Agency’s (U.S. EPA’s) Clean Air Status and Trends Network (CASTNet) currently uses filter packs to measure weekly integrated concentrations. The U.S. EPA is interested in supplementing CASTNet with semi-continuou...

  6. Characterization of a Photoacoustic Aerosol Absorption Spectrometer for Aircraft-based Measurements

    NASA Astrophysics Data System (ADS)

    Mason, B. J.; Wagner, N. L.; Richardson, M.; Brock, C. A.; Murphy, D. M.; Adler, G.

    2015-12-01

    Atmospheric aerosol directly impacts the Earth's climate through extinction of incoming and outgoing radiation. The optical extinction is due to both scattering and absorption. In situ measurements of aerosol extinction and scattering are well established and have uncertainties less than 5%. However measurements of aerosol absorption typically have uncertainties of 20-30%. Development and characterization of more accurate and precise instrumentation for measurement of aerosol absorption will enable a deeper understand of significance and spatial distribution of black and brown carbon aerosol, the effect of atmospheric processes on aerosol optical properties, and influence of aerosol optical properties on direct radiative forcing. Here, we present a detailed characterization of a photoacoustic aerosol absorption spectrometer designed for deployment aboard research aircraft. The spectrometer operates at three colors across the visible spectrum and is calibrated in the field using ozone. The field calibration is validated in the laboratory using synthetic aerosol and simultaneous measurements of extinction and scattering. In addition, the sensitivity of the instrument is characterized under conditions typically encountered during aircraft sampling e.g. as a function of changing pressure. We will apply this instrument characterization to ambient aerosol absorption data collected during the SENEX and SEAC4RS aircraft based field campaigns.

  7. Collection efficiency of the soot-particle aerosol mass spectrometer (SP-AMS) for internally mixed particulate black carbon

    NASA Astrophysics Data System (ADS)

    Willis, M. D.; Lee, A. K. Y.; Onasch, T. B.; Fortner, E. C.; Williams, L. R.; Lambe, A. T.; Worsnop, D. R.; Abbatt, J. P. D.

    2014-12-01

    The soot-particle aerosol mass spectrometer (SP-AMS) uses an intra-cavity infrared laser to vaporize refractory black carbon (rBC) containing particles, making the particle beam-laser beam overlap critical in determining the collection efficiency (CE) for rBC and associated non-refractory particulate matter (NR-PM). This work evaluates the ability of the SP-AMS to quantify rBC and NR-PM mass in internally mixed particles with different thicknesses of organic coating. Using apparent relative ionization efficiencies for uncoated and thickly coated rBC particles, we report measurements of SP-AMS sensitivity to NR-PM and rBC, for Regal Black, the recommended particulate calibration material. Beam width probe (BWP) measurements are used to illustrate an increase in sensitivity for highly coated particles due to narrowing of the particle beam, which enhances the CE of the SP-AMS by increasing the laser beam-particle beam overlap. Assuming complete overlap for thick coatings, we estimate CE for bare Regal Black particles of 0.6 ± 0.1, which suggests that previously measured SP-AMS sensitivities to Regal Black were underestimated by up to a factor of 2. The efficacy of the BWP measurements is highlighted by studies at a busy road in downtown Toronto and at a non-roadside location, which show particle beam widths similar to, but greater than that of bare Regal Black and coated Regal Black, respectively. Further BWP measurements at field locations will help to constrain the range of CE for fresh and aged rBC-containing particles. The ability of the SP-AMS to quantitatively assess the composition of internally mixed particles is validated through measurements of laboratory-generated organic coated particles, which demonstrate that the SP-AMS can quantify rBC and NR-PM over a wide range of particle compositions and rBC core sizes.

  8. In Situ Electrostatic Separation of Ambient PM2.5 into Source-Specific Fractions During Collection in a FRM Sampler

    SciTech Connect

    Naresh Shah; Frank E. Huggins; Gerald P. Huffman

    2006-07-31

    Coal combustion is generally viewed as a major source of PM2.5 emissions into the atmosphere. For some time, toxicologists have been asking for an exposure environment enriched with the coal combustion source specific PM{sub 2.5} to conduct meaningful exposure studies to better understand the mechanisms of the adverse health effects of coal combustion specific PM2.5 in the ambient environment. There are several unique characteristics of primary PM generated from coal combustion. In this research project, an attempt has been made to exploit some of the unique properties of PM generated from coal fired power plants to preferentially separate them out from the rest of the primary and secondary PM in the ambient environment. An existing FRM sampler used for monitoring amount of PM{sub 2.5} in the ambient air is modified to incorporate an electrostatic field. A DC corona charging device is also installed at the ambient air inlet to impart positive or negative charge to the PM. Visual Basic software has been written to simulate the lateral movement of PM as it passes through the electrostatic separator under varying operating conditions. The PM samples collected on polycarbonate filters under varying operating conditions were extensively observed for clustering and/or separation of PM in the direction parallel to the electric field. No systematic PM separation was observed under any of the operating conditions. A solution to overcome this kind of turbulence caused remixing has been offered. However, due to major programmatic changes in the DOE UCR program, there are no venues available to further pursue this research.

  9. Semi-automated bacterial spore detection system with micro-fluidic chips for aerosol collection, spore treatment and ICAN DNA detection.

    PubMed

    Inami, Hisao; Tsuge, Kouichiro; Matsuzawa, Mitsuhiro; Sasaki, Yasuhiko; Togashi, Shigenori; Komano, Asuka; Seto, Yasuo

    2009-07-15

    A semi-automated bacterial spore detection system (BSDS) was developed to detect biological threat agents (e.g., Bacillus anthracis) on-site. The system comprised an aerosol sampler, micro-fluidic chip-A (for spore germination and cell lysis), micro-fluidic chip-B (for extraction and detection of genomic DNA) and an analyzer. An aerosol with bacterial spores was first collected in the collection chamber of chip-A with a velocity of 300 l/min, and the chip-A was taken off from the aerosol sampler and loaded into the analyzer. Reagents packaged in the chip-A were sequentially applied into the chamber. The genomic DNA extract from spore lyzate was manually transferred from chip-A to chip-B and loaded into the analyzer. Genomic DNA in chip-B was first trapped on a glass bead column, washed with various reagents, and eluted to the detection chamber by sequential auto-dispensing. Isothermal and chimeric primer-initiated amplification of nucleic acids (ICAN) with fluorescent measurement was adopted to amplify and detect target DNA. Bacillus subtilis was the stimulant of biological warfare agent in this experiment. Pretreatment conditions were optimized by examining bacterial target DNA recovery in the respective steps (aerosol collection, spore germination, cell lysis, and DNA extraction), by an off-chip experiment using a real-time polymerase chain reaction quantification method. Without the germination step, B. subtilis spores did not demonstrate amplification of target DNA. The detection of 10(4) spores was achieved within 2h throughout the micro-fluidic process. PMID:19450964

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

    NASA Astrophysics Data System (ADS)

    Hearn, John D.; Smith, Geoffrey D.

    2006-12-01

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

  11. AMS-C14 analysis of graphite obtained with an Automated Graphitization Equipment (AGE III) from aerosol collected on quartz filters

    NASA Astrophysics Data System (ADS)

    Solís, C.; Chávez, E.; Ortiz, M. E.; Andrade, E.; Ortíz, E.; Szidat, S.; Wacker, L.

    2015-10-01

    AMS-14C applications often require the analysis of small samples. Such is the case of atmospheric aerosols where frequently only a small amount of sample is available. The ion beam physics group at the ETH, Zurich, has designed an Automated Graphitization Equipment (AGE III) for routine graphite production for AMS analysis from organic samples of approximately 1 mg. In this study, we explore the potential use of the AGE III for graphitization of particulate carbon collected in quartz filters. In order to test the methodology, samples of reference materials and blanks with different sizes were prepared in the AGE III and the graphite was analyzed in a MICADAS AMS (ETH) system. The graphite samples prepared in the AGE III showed recovery yields higher than 80% and reproducible 14C values for masses ranging from 50 to 300 μg. Also, reproducible radiocarbon values were obtained for aerosol filters of small sizes that had been graphitized in the AGE III. As a study case, the tested methodology was applied to PM10 samples collected in two urban cities in Mexico in order to compare the source apportionment of biomass and fossil fuel combustion. The obtained 14C data showed that carbonaceous aerosols from Mexico City have much lower biogenic signature than the smaller city of Cuernavaca.

  12. The heterogeneous reaction of hydroxyl radicals with sub-micron squalane particles: a model system for understanding the oxidative aging of ambient aerosols

    NASA Astrophysics Data System (ADS)

    Smith, J. D.; Kroll, J. H.; Cappa, C. D.; Che, D. L.; Liu, C. L.; Ahmed, M.; Leone, S. R.; Worsnop, D. R.; Wilson, K. R.

    2009-02-01

    The heterogeneous reaction of OH radicals with sub-micron squalane particles, in the presence of O2, is used as a model system to explore the fundamental chemical mechanisms that control the oxidative aging of organic aerosols in the atmosphere. Detailed kinetic measurements combined with elemental mass spectrometric analysis reveal that the reaction proceeds sequentially by adding an average of one oxygenated functional group per reactive loss of squalane. The reactive uptake coefficient of OH with squalane particles is determined to be 0.3±0.07 at an average OH concentration of ~1×1010 molecules·cm-3. Based on a comparison between the measured particle mass and model predictions it appears that significant volatilization of a reduced organic particle would be extremely slow in the real atmosphere. However, as the aerosols become more oxygenated, volatilization becomes a significant loss channel for organic material in the particle phase. Together these results provide a chemical framework in which to understand how heterogeneous chemistry transforms the physiochemical properties of particle phase organic matter in the troposphere.

  13. The heterogeneous reaction of hydroxyl radicals with sub-micron squalane particles: a model system for understanding the oxidative aging of ambient aerosols

    NASA Astrophysics Data System (ADS)

    Smith, J. D.; Kroll, J. H.; Cappa, C. D.; Che, D. L.; Liu, C. L.; Ahmed, M.; Leone, S. R.; Worsnop, D. R.; Wilson, K. R.

    2009-05-01

    The heterogeneous reaction of OH radicals with sub-micron squalane particles, in the presence of O2, is used as a model system to explore the fundamental chemical mechanisms that control the oxidative aging of organic aerosols in the atmosphere. Detailed kinetic measurements combined with elemental mass spectrometric analysis reveal that the reaction proceeds sequentially by adding an average of one oxygenated functional group per reactive loss of squalane. The reactive uptake coefficient of OH with squalane particles is determined to be 0.3±0.07 at an average OH concentration of ~1×1010 molecules cm-3. Based on a comparison between the measured particle mass and model predictions it appears that significant volatilization of a reduced organic particle would be extremely slow in the real atmosphere. However, as the aerosols become more oxygenated, volatilization becomes a significant loss channel for organic material in the particle-phase. Together these results provide a chemical framework in which to understand how heterogeneous chemistry transforms the physiochemical properties of particle-phase organic matter in the troposphere.

  14. Spatial and Temporal Distribution of Water-Soluble Anions and Organic Carbons in Bulk Aerosols Collected at the Ryukyu Islands, Okinawa, Japan

    NASA Astrophysics Data System (ADS)

    Somada, Y.; Azechi, S.; Ijyu, M.; Nakaema, F.; Handa, D.; Oshiro, Y.; Miyagi, Y.; Arakaki, T.; Tanahara, A.; Furukawa, M.

    2011-12-01

    Atmospheric aerosols pose health risks to humans and change global climate. Ryukyu Islands in Japan are mainly covered with maritime air mass in summer and continental air mass for the rest of the seasons. Thus, it is possible to estimate the origins of chemical components, in particular transboundary air pollutants from East Asia. Ryukyu Islands are one of the best locations for monitoring the changes in Asia's atmosphere. This study tried to elucidate the spatial and temporal distribution of water-soluble anions and organic carbons, and chemical changes during the transportation processes. Aerosol samples were collected at Cape Hedo Atmosphere and Aerosol Monitoring Station (CHAAMS, Sep. 2005 - Dec. 2010), Kume Island (KM, ca. 100 km from Naha), and Minami-Daitou Island (MD, ca. 350 km from Naha) from June 2008 to June 2010 on quartz filters by using identical high-volume air samplers. The sample filters were exchanged every week. The concentrations of water-soluble anions (Cl-,Br-,NO3-,NO2-,SO42-) and water-soluble organic carbon (WSOC) were determined by using ion chromatography and total organic carbon analyzer, respectively. And, concentrations of non-sea-salt SO(nss-SO42-) were calculated based on the concentrations of Na+. For the samples collected at CHAAMS, seawater component accounted for on average 56±5% of total aerosol mass. Monthly mean concentrations of nss-SO42- showed distinctive difference among the sampling sites (KM>CHAAMS>MD) during Jan. to May, suggesting that distance from Asian continent affected on its behavior. Yearly average concentrations of NO3- and nss-SO42- showed +42% and +16% increase, respectively between 2005 and 2011. Annual rate of NO3- increase was much faster than that of nss-SO42-, probably reflecting changes in lifestyles in Asian continent.

  15. Mechanism for production of secondary organic aerosols and their representation in atmospheric models. Final report

    SciTech Connect

    Seinfeld, J.H.; Flagan, R.C.

    1999-06-07

    This document contains the following: organic aerosol formation from the oxidation of biogenic hydrocarbons; gas/particle partitioning of semivolatile organic compounds to model inorganic, organic, and ambient smog aerosols; and representation of secondary organic aerosol formation in atmospheric models.

  16. The Role of Aerosol Composition in Arctic Cloud Formation

    NASA Astrophysics Data System (ADS)

    Brooks, S. D.; Hiranuma, N.; Moffet, R.; Laskin, A.; Gilles, M. K.; Glen, A.

    2010-12-01

    While it has been shown that aerosol size has a direct correlation with its ability to act as an ice nucleus, the role of the composition of freshly emitted and evolving aerosol in nucleation is poorly understood. Here we use combined measurements of ice nucleation and high resolution single particle composition to provide insight on the connection between aerosol composition in ice nucleation. These measurements were collected during the Indirect and Semidirect Aerosols Campaign (ISDAC) over Barrow, AK in the springtime of 2008. In-situ ice nucleation measurements were conducted using the Texas Continuous Flow Diffusion Chamber (CFDC). The composition of ambient particles as well as residuals of cloud droplets and ice crystals were studied on a particle by particle basis using computer controlled scanning electron microscopy with energy dispersive X-ray analysis (CCSEM/EDX) and scanning transmission X-Ray microscopy coupled with near edge X-ray absorption spectroscopy (STXM/NEXAFAS). Observed IN concentrations varied from frequent values of 0.01 per liter to more than 10 per liters, depending on conditions and the availability of ice-nucleating aerosols. Ice crystals residuals collected in a fully glaciated cloud demonstrate that both particle chemistry and size requirement must be met for a particle to be an efficient ice nucleus. According to the STXM/NEXAFAS spectral maps, ice crystals residuals are characterized by insoluble cores of either large brown or black carbon (BBC) or carbonates coated by water soluble organics. In contrast, in ambient air samples collected from a biomass burning plume, many organic particles were also observed, but these were smaller and did not have insoluble cores. In-situ ice nucleation measurements show that these biomass particles have inferior ice nuclei ability, relative to those collected in the glaciated cloud. Taken together our measurements suggest that two key elements, a critical size (provided by BBC and/or carbonate

  17. Characterization of Organic Nitrogen in the Atmosphere Using High Resolution Aerosol Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Ge, X.; Sun, Y.; Chen, M.; Zhang, Q.

    2015-12-01

    Despite extensive efforts on characterizing organic nitrogen (ON) compounds in atmospheric aerosols and aqueous droplets, knowledge of ON chemistry is still limited, mainly due to its chemical complexity and lack of highly time-resolved measurements. This work is aimed at optimizing the method of using Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-AMS) to characterize ON compounds in atmospheric aerosols. Seventy-five pure nitrogen-containing organic compounds covering a variety of functional groups were analyzed with the HR-AMS. Our results show that ON compounds commonly produce NHx+, NOx+, which are usually attributed to inorganic N species such as ammonium and nitrate, and CH2N+ at m/z = 28, which is rarely quantified in ambient aerosol due to large interference from N2+ in the air signal. As a result, using the nitrogen-to-carbon (N/C) calibration factor proposed by Aiken et al. (2008) on average leads to ~ 20% underestimation of N/C in ambient organic aerosol. A new calibration factor of 0.79 is proposed for determining the average N/C in organics. The relative ionization efficiencies (RIEs) of different ON species, on average, are found to be consistent with the default RIE value (1.4) for the total organics. The AMS mass spectral features of various types of ON species (amines, amides, amino acids, etc.) are examined and used for characterizing ON composition in ambient aerosols. Our results indicate that submicron organic aerosol measured during wintertime in Fresno, CA contains significant amounts of amino-compounds whereas more diversified ON species, including N-containing aromatic heterocycle (e.g., imidazoles), are observed in fog waters collected simultaneously. Our findings have important implications for understanding atmospheric ON behaviors via the widespread HR-AMS measurements of ambient aerosols and droplets.

  18. Collection efficiency of the Soot-Particle Aerosol Mass Spectrometer (SP-AMS) for internally mixed particulate black carbon

    DOE PAGESBeta

    Willis, M. D.; Lee, A. K. Y.; Onasch, T. B.; Fortner, E. C.; Williams, L. R.; Lambe, A. T.; Worsnop, D. R.; Abbatt, J. P. D.

    2014-05-26

    The soot-particle aerosol mass spectrometer (SP-AMS) uses an intra-cavity infrared laser to vaporize refractory black carbon (rBC) containing particles, making the particle beam–laser beam overlap critical in determining the collection efficiency (CE) for rBC and associated non-refractory particulate matter (NR-PM). This work evaluates the ability of the SP-AMS to quantify rBC and NR-PM mass in internally mixed particles with different thicknesses of organic coating. Using apparent relative ionization efficiencies for uncoated and thickly coated rBC particles, we report measurements of SP-AMS sensitivity to NR-PM and rBC, for Regal Black, the recommended particulate calibration material. Beam width probe (BWP) measurements aremore » used to illustrate an increase in sensitivity for highly coated particles due to narrowing of the particle beam, which enhances the CE of the SP-AMS by increasing the laser beam–particle beam overlap. Assuming complete overlap for thick coatings, we estimate CE for bare Regal Black particles of 0.6 ± 0.1, which suggests that previously measured SP-AMS sensitivities to Regal Black were underestimated by up to a factor of two. The efficacy of the BWP measurements is highlighted by studies at a busy road in downtown Toronto and at a non-roadside location, which show particle beam widths similar to, but greater than that of bare Regal Black and coated Regal Black, respectively. Further BWP measurements at field locations will help to constrain the range of CE for fresh and aged rBC-containing particles. The ability of the SP-AMS to quantitatively assess the composition of internally mixed particles is validated through measurements of laboratory-generated organic coated particles, which demonstrate that the SP-AMS can quantify rBC and NR-PM over a wide range of particle compositions and rBC core sizes.« less

  19. Collection efficiency of the soot-particle aerosol mass spectrometer (SP-AMS) for internally mixed particulate black carbon

    DOE PAGESBeta

    Willis, M. D.; Lee, A. K. Y.; Onasch, T. B.; Fortner, E. C.; Williams, L. R.; Lambe, A. T.; Worsnop, D. R.; Abbatt, J. P. D.

    2014-12-18

    The soot-particle aerosol mass spectrometer (SP-AMS) uses an intra-cavity infrared laser to vaporize refractory black carbon (rBC) containing particles, making the particle beam–laser beam overlap critical in determining the collection efficiency (CE) for rBC and associated non-refractory particulate matter (NR-PM). This work evaluates the ability of the SP-AMS to quantify rBC and NR-PM mass in internally mixed particles with different thicknesses of organic coating. Using apparent relative ionization efficiencies for uncoated and thickly coated rBC particles, we report measurements of SP-AMS sensitivity to NR-PM and rBC, for Regal Black, the recommended particulate calibration material. Beam width probe (BWP) measurements aremore » used to illustrate an increase in sensitivity for highly coated particles due to narrowing of the particle beam, which enhances the CE of the SP-AMS by increasing the laser beam–particle beam overlap. Assuming complete overlap for thick coatings, we estimate CE for bare Regal Black particles of 0.6 ± 0.1, which suggests that previously measured SP-AMS sensitivities to Regal Black were underestimated by up to a factor of 2. The efficacy of the BWP measurements is highlighted by studies at a busy road in downtown Toronto and at a non-roadside location, which show particle beam widths similar to, but greater than that of bare Regal Black and coated Regal Black, respectively. Further BWP measurements at field locations will help to constrain the range of CE for fresh and aged rBC-containing particles. The ability of the SP-AMS to quantitatively assess the composition of internally mixed particles is validated through measurements of laboratory-generated organic coated particles, which demonstrate that the SP-AMS can quantify rBC and NR-PM over a wide range of particle compositions and rBC core sizes.« less

  20. Classification of collective behavior: a comparison of tracking and machine learning methods to study the effect of ambient light on fish shoaling.

    PubMed

    Butail, Sachit; Salerno, Philip; Bollt, Erik M; Porfiri, Maurizio

    2015-12-01

    Traditional approaches for the analysis of collective behavior entail digitizing the position of each individual, followed by evaluation of pertinent group observables, such as cohesion and polarization. Machine learning may enable considerable advancements in this area by affording the classification of these observables directly from images. While such methods have been successfully implemented in the classification of individual behavior, their potential in the study collective behavior is largely untested. In this paper, we compare three methods for the analysis of collective behavior: simple tracking (ST) without resolving occlusions, machine learning with real data (MLR), and machine learning with synthetic data (MLS). These methods are evaluated on videos recorded from an experiment studying the effect of ambient light on the shoaling tendency of Giant danios. In particular, we compute average nearest-neighbor distance (ANND) and polarization using the three methods and compare the values with manually-verified ground-truth data. To further assess possible dependence on sampling rate for computing ANND, the comparison is also performed at a low frame rate. Results show that while ST is the most accurate at higher frame rate for both ANND and polarization, at low frame rate for ANND there is no significant difference in accuracy between the three methods. In terms of computational speed, MLR and MLS take significantly less time to process an image, with MLS better addressing constraints related to generation of training data. Finally, all methods are able to successfully detect a significant difference in ANND as the ambient light intensity is varied irrespective of the direction of intensity change.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  2. Tracing Ambient Air Geochemistry using a Modified X-Ray Fluorescence Filter Method

    NASA Astrophysics Data System (ADS)

    Steiner, J. C.; Rudolph, E.; Wrice, T.

    2002-12-01

    Modifications of x-ray fluorescence counting procedures enable tracing of aerosol dispersals related to weather fronts and local weather phenomena. Improved X-ray fluorescence methods for bulk aerosols deposited under positive air pressure conditions onto Millipore filters at 80 liters/hour enable the tracing of geological samples in periods down to one hour. Vacuum-plating aliquots of USGS standards onto 0.2 micron polycarbonate and quartz Millipore filters create standards with a shelf life of several months. The analytical system permits detection of light oxides, such as silica to 10 ppm, and heavy elements, such as iron to 0.5 ppm. These collections allow discriminations to be drawn between dominantly geological, silica-enriched air mass and dominantly iron-enriched air of possible industrial origin. These ambient air collections at 120 feet elevation at City College are used to create possible distinctions in air masses related to points of origin. Splits of aerosol examined by neutron activation and coupled plasma emission spectroscopy agree with x-ray fluorescence methods to within analytical error. Aerosol flux conditions are monitored for speciation using direct examination by scanning electron microscopy with energy dispersive analytical capability plus aerosol physical properties by sun photometry. The latter provides bulk optical transmission at six major wavelengths and estimates for bulk aerosol size properties. Preliminary data show positive photometry links with iron-aerosols with a correlation coefficient with southwesterly wind-driven conditions of seventy percent over a four hour monitoring period. Aerosol flux comparisons with heavy metal populations, Ba, Rb, Zr, La show uniform distributions with iron- and silica-enriched populations indicating a pervasive background condition in the ambient air mass over New York City.

  3. Chemical composition of size-segregated aerosol collected all year-round at Concordia Station (Dome C, Antarctica). Transport processes and climatic implications.

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    Ice-core stratigraphies of chemical components of atmospheric gases and aerosols trapped in the snow layers by scavenging processes are a powerful tool in understanding past climatic and environmental changes. The deep ice core drilled at Dome C in the framework of the EPICA project allowed reconstructing the last 8 glacial-interglacial cycles and highlightened the complex relationships between climatic forcings and environmental feedback processes. In interpreting ice core records as a function of past climatic variations, some difficulties arise from uncertainties in considering selected chemical species as reliable markers of climatic and environmental processes and in attributing the different load and composition of aerosols over Antarctica to changes in source intensity (such as aridity, wind strength, emersion of continental platform by sea-level lowering etc..) and/or to variations in atmospheric processes (such as meridional and zonal atmospheric circulation, polar vortex intensity, scavenging efficiency, transport pathways etc..). Besides, two new aspects are actually under discussions: the possible use of Na as sea-ice cover marker (via frost flower formation on the sea-ice surface during the pack-ice formation) and the identification of continental source areas for mineral dust reaching internal regions of Antarctica during glacial and interglacial periods. In order to better address such controversial issues, since 2005 a continuous, high temporal resolution size-segregated aerosol and surface snow sampling has been performed at Dome C (central East Antarctic Plateau, 75° 06' S, 123° 23' E), in the framework of "Station Concordia" Project (a Italian PNRA- French IPEV joint program). The chemical analysis of size-segregated aerosol and daily superficial snow samples, collected all year-round for more than 4 years, can contribute to clarify some of the above mentioned topics. In particular: the possible seasonal pattern of sea spray aerosol could be

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

    SciTech Connect

    Baustian, Kelly J.; Cziczo, Daniel J.; Wise, M. A.; Pratt, Kerri; Kulkarni, Gourihar R.; Hallar, Anna G.; Tolbert, Margaret A.

    2012-03-30

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  7. Single-particle characterization of atmospheric aerosols collected at Gosan, Korea, during the Asian Pacific Regional Aerosol Characterization Experiment field campaign using low-Z (atomic number) particle electron probe X-ray microanalysis.

    PubMed

    Geng, Hong; Cheng, Fangqin; Ro, Chul-Un

    2011-11-01

    A quantitative energy-dispersive electron probe X-ray microanalysis (ED-EPMA), namely low-Z (atomic number) particle EPMA, was used to characterize the chemical compositions of the individual aerosol particles collected at the Gosan supersite, Jeju Island, Korea, as a part of the Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia). On 4-10 April 2001 just before a severe dust storm arrived, seven sets of aerosol samples were obtained by a seven-stage May cascade impactor with a flow rate of 20 L/min. Overall 11,200 particles on stages 1-6 with cutoff diameters of 16, 8, 4, 2, 1, and 0.5 microm, respectively, were examined and classified based on their secondary electron images and X-ray spectra. In general, sea salt particles were the most frequently encountered, followed by mineral dust, organic carbon (OC)-like, (NH4)2SO4/NH4HSO4-containing, elemental carbon (EC)-like, Fe-rich, and K-rich particles. Sea salt and mineral dust particles had a higher relative abundance on stages 1-5, whereas OC-like, (NH4)2SO4/NH4HSO4-containing, Fe-rich, and K-rich particles were relatively abundant on stage 6. The analysis on relative number abundances of various particle types combined with 72-hr backward air mass trajectories indicated that a lot of reacted sea salt and reacted mineral dust (with airborne NOx and SO2 or their acidic products) and OC-like particles were carried by the air masses passing over the Yellow Sea (for sample "10 April") and many NH4HSO4/ (NH4)2SO4-containing particles were carried by the air masses passing over the Sea of Japan and Korea Strait (for samples "4-9 April"). It was concluded that the atmosphere over Jeju Island was influenced by anthropogenic SO2 and NOx, organic compounds, and secondary aerosols when Asian dust was absent.

  8. Influence of Humidity on the Aerosol Scattering Coefficient and Its Effect on the Upwelling Radiance During ACE-2

    NASA Technical Reports Server (NTRS)

    Gasso, B. S.; Hegg, D. A.; Covert, D. S.; Collins, D.; Noone, K.; Oestroem, E.; Schmid, B.; Russell, P. B.; Livingston, J. M.; Durkee, P. A.; Jonsson, H.

    2000-01-01

    Aerosol scattering coefficients (sigma(sub sp)) have been measured over the ocean at different relative humidities (RH) as a function of attitude in the region surrounding the Canary Islands during the Second Aerosol Characterization Experiment (ACE-2) in June and July 1997. The data were collected by the University of Washington passive humidigraph (UWPH) mounted on the Pelican research aircraft. Concurrently, particle size distributions absorption coefficients and aerosol optical depth were measured throughout 17 flights. A parameterization of sigma(sub sp) as a function of RH was utilized to assess the impact of aerosol hydration on the upwelling radiance (normalized to the solar constant and cosine of zenith angle). The top of the atmosphere radiance signal was simulated at wavelengths corresponding to visible and near-infrared bands or the EOS-AM ("Terra") detectors, MODIS and MISR. The UWPH measured (sigma(sub sp)) at 2 RHs, one below and the other above ambient conditions. Ambient (sigma(sub sp)) was obtained by interpolation of these 2 measurements. The data were stratified in terms of 3 types of aerosols: Saharan dust, clean marine (marine boundary layer background) and polluted marine aerosols (i.e., 2- or 1-day old polluted aerosols advected from Europe). An empirical relation for the dependence of (sigma(sub sp)) on RH, defined by (sigma(sub sp))(RH) = k. ((1 - RH/100)(exp -gamma), was used with the hygroscopic exponent gamma derived from the data. The following gamma values were obtained for the 3 aerosol types: gamma(dust) = 0.23 +/- 0.05, gamma(clean marine) = 0.69 +/- 0.06 and gamma(polluted marine) = 0.57 + 0.06. Based on the measured (gamma)(s), the above equation was utilized to derive aerosol models with different hygroscopicities. The satellite simulation signal code 6S was used to compute the upwelling radiance corresponding to each of those aerosol models at several ambient humidities. For the pre-launch estimated precision of the sensors and

  9. Influence of Humidity On the Aerosol Scattering Coefficient and Its Effect on the Upwelling Radiance During ACE-2

    NASA Technical Reports Server (NTRS)

    Gasso, S.; Hegg, D. A.; Covert, D. S.; Collins, D.; Noone, K. J.; Oestroem, E.; Schmid, B.; Russell, P. B.; Livingston, J. M.; Durkee, P. A.

    2000-01-01

    Aerosol scattering coefficients (sigma(sub sp)) have been measured over the ocean at different relative humidities (RH) as a function of altitude in the region surrounding the Canary Islands during the Second Aerosol Characterization Experiment (ACE-2) in June and July 1997. The data were collected by the University of Washington passive humidigraph (UWPH) mounted on the Pelican research aircraft. Concurrently, particle size distributions, absorption coefficients and aerosol optical depth were measured throughout 17 flights. A parameterization of sigma(sub sp) as a function of RH was utilized to assess the impact of aerosol hydration on the upwelling radiance (normalized to the solar constant and cosine of zenith angle). The top of the atmosphere radiance signal was simulated at wavelengths corresponding to visible and near-infrared bands of the EOS (Earth Observing System) AM-1 (Terra) detectors, MODIS (Moderate Resolution Imaging Spectroradiometer) and MISR (Multi-angle Imaging Spectroradiometer). The UWPH measured sigma(sub sp) at two RHs, one below and the other above ambient conditions. Ambient sigma(sub sp) was obtained by interpolation of these two measurements. The data were stratified in terms of three types of aerosols: Saharan dust, clean marine (marine boundary layer background) and polluted marine aerosols (i.e., two- or one-day old polluted aerosols advected from Europe). An empirical relation for the dependence of sigma(sub sp) on RH, defined by sigma(sub sp)(RH) = k.(1 - RH/100)(sup gamma), was used with the hygroscopic exponent gamma derived from the data. The following gamma values were obtained for the 3 aerosol types: gamma(dust) = 0.23 +/- 0.05, gamma(clean marine) = 0.69 +/- 0.06 and gamma(polluted marine) = 0.57 +/- 0.06. Based on the measured gammas, the above equation was utilized to derive aerosol models with different hygroscopicities. The satellite simulation signal code 6S was used to compute the upwelling radiance corresponding to each

  10. Aerosolization of fungi, (1→3)-β-D glucan, and endotoxin from flood-affected materials collected in New Orleans homes

    PubMed Central

    Adhikari, Atin; Jung, Jaehee; Reponen, Tiina; Lewis, Jocelyn Suzanne; DeGrasse, Enjoli C.; Grimsley, L. Faye; Chew, Ginger L.; Grinshpun, Sergey A.

    2015-01-01

    Standing water and sediments remaining on flood-affected materials were the breeding ground for many microorganisms in flooded homes following Hurricane Katrina. The purpose of this laboratory study was to examine the aerosolization of culturable and total fungi, (1→3)-β-D glucan, and endotoxin from eight flood-affected floor and bedding materials collected in New Orleans homes, following Hurricane Katrina. Aerosolization was examined using the Fungal Spore Source Strength Tester (FSSST) connected to a BioSampler. Dust samples were collected by vacuuming. A two-stage cyclone sampler was used for size-selective analysis of aerosolized glucan and endotoxin. On average, levels of culturable fungi ranged from undetectable (lower limit = 8.3×104) to 2.6×105 CFU/m2; total fungi ranged from 2.07×105 to 1.6×106 spores/m2; (1→3)-β-D glucan and endotoxin were 2.0×103 – 2.9×104 ng/m2 and 7.0×102 – 9.3×104 EU/m2, respectively. The results showed that 5–15 min sampling is sufficient for detecting aerosolizable biocontaminants with the FSSST. Smaller particle size fractions (<1.0 μm and <1.8 μm) have levels of glucan and endotoxin comparable to larger (>1.8 μm) fractions, which raises additional exposure concerns. Vacuuming was found to overestimate inhalation exposure risks by a factor of approximately 102 for (1→3)-β-D glucan and by 103 to 104 for endotoxin as detected by the FSSST. The information generated from this study is important with respect to restoration and rejuvenation of the flood-affected areas in New Orleans. We believe the findings will be significant during similar disasters in other regions of the world including major coastal floods from tsunamis. PMID:19201399

  11. Comparison of Fe(II) Photo-Formation Characteristics Between Aqueous Humic Acid Solutions and Aqueous Extracts of Atmospheric Aerosols Collected at Okinawa Island, Japan

    NASA Astrophysics Data System (ADS)

    Saito, K.; Okada, K.; Arakaki, T.

    2007-12-01

    Photochemical cycles of Fe(III)-Fe(II) affects the oxidation and the reduction of transient species such as active oxygen species and various transition metals in the atmospheric condensed phases. Although the importance of organic ligands to iron cycling (e.g. ligand-to-metal charge transfer) is becoming clearer, the mechanism by which photochemical reduction of Fe(III) to Fe(II) are not well understood. Humic acid (HA) is considered as an important organic ligand for Fe(III) complexes in the environment. HA is a collection of organic compounds that exist in nature but whose structures are not well known. Commercially available HAs as received from the manufacturers contain trace amount of iron. Using this residual Fe, we investigated the photochemical formation of Fe(II) in aqueous HA solutions to elucidate the photochemical cycles of Fe(III)-Fe(II) in the atmospheric water drops. We purchased HAs from several different suppliers. We investigated the effects of pH and wavelengths on Fe(II) photo-formation using monochromatic radiations at 313, 334, 366, and 405 nm. Concentrations of photochemically formed Fe(II) were determined by ferrozine-HPLC technique, and the apparent quantum yields were determined based on the total absorbance of the HA solutions. Fe(II) photo-formation characteristics of the aqueous humic acid solutions purchased from different suppliers showed slightly different wavelength dependence. Furthermore, we compared Fe(II) photoformation characteristics observed in aqueous HA solutions with those in the aqueous extracts of atmospheric aerosols collected in Okinawa, Japan. The results showed that the apparent quantum yields of the aerosol extracts were 5-10 times higher than those of the HA solutions. Wavelength-dependence of Fe(II) photo-formation observed in the aqueous extracts of aerosols was similar to that seen in the aqueous HA solutions.

  12. Using Satellite Aerosol Retrievals to Monitor Surface Particulate Air Quality

    NASA Technical Reports Server (NTRS)

    Levy, Robert C.; Remer, Lorraine A.; Kahn, Ralph A.; Chu, D. Allen; Mattoo, Shana; Holben, Brent N.; Schafer, Joel S.

    2011-01-01

    The MODIS and MISR aerosol products were designed nearly two decades ago for the purpose of climate applications. Since launch of Terra in 1999, these two sensors have provided global, quantitative information about column-integrated aerosol properties, including aerosol optical depth (AOD) and relative aerosol type parameters (such as Angstrom exponent). Although primarily designed for climate, the air quality (AQ) community quickly recognized that passive satellite products could be used for particulate air quality monitoring and forecasting. However, AOD and particulate matter (PM) concentrations have different units, and represent aerosol conditions in different layers of the atmosphere. Also, due to low visible contrast over brighter surface conditions, satellite-derived aerosol retrievals tend to have larger uncertainty in urban or populated regions. Nonetheless, the AQ community has made significant progress in relating column-integrated AOD at ambient relative humidity (RH) to surface PM concentrations at dried RH. Knowledge of aerosol optical and microphysical properties, ambient meteorological conditions, and especially vertical profile, are critical for physically relating AOD and PM. To make urban-scale maps of PM, we also must account for spatial variability. Since surface PM may vary on a finer spatial scale than the resolution of standard MODIS (10 km) and MISR (17km) products, we test higher-resolution versions of MODIS (3km) and MISR (1km research mode) retrievals. The recent (July 2011) DISCOVER-AQ campaign in the mid-Atlantic offers a comprehensive network of sun photometers (DRAGON) and other data that we use for validating the higher resolution satellite data. In the future, we expect that the wealth of aircraft and ground-based measurements, collected during DISCOVER-AQ, will help us quantitatively link remote sensed and ground-based measurements in the urban region.

  13. Chemical characterization of the ambient organic aerosol soluble in water: 1. Isolation of hydrophobic and hydrophilic fractions with a XAD-8 resin

    NASA Astrophysics Data System (ADS)

    Sullivan, Amy P.; Weber, Rodney J.

    2006-03-01

    Group separation of the aqueous extract of fine particles bearing water-soluble organic carbon (WSOC) provides unique insights into the sources of organic carbon (OC). XAD-8 resin coupled with a Total Organic Carbon analyzer allows for direct quantification. We term the fraction of WSOC not retained by a XAD-8 resin column at pH 2 as hydrophilic WSOC (WSOCxp); this includes saccharides, amines, and carbonyls and aliphatic monocarboxylic/dicarboxylic/oxocarboxylic acids with less than 4 or 5 carbons. The fraction of WSOC retained by XAD-8, termed the hydrophobic fraction (WSOCxr), include aromatic acids, phenols, organic nitrates, cyclic acids, and carbonyls and monocarboxylic/dicarboxylic acids with greater than 3 or 4 carbons. However, only aromatic compounds (or aromatic-like compounds with similar properties) can subsequently be extracted from XAD-8 with high efficiency. By coupling a Particle-into-Liquid Sampler with this technique, online measurements of WSOC, WSOCxp, and WSOCxr are possible. Urban measurements from St. Louis and Atlanta, on a carbon mass basis, show an increase in the mean WSOC fraction from winter (51%) to summer (61%), due to increases in the WSOCxp/OC from 0.25 to 0.35. During a summer Atlanta PM event, WSOC to OC was 0.75, driven largely by increases in the WSOCxp. The results are consistent with the view that in the summer, there are increased amounts of oxygenated polar compounds, possibly from secondary organic aerosol production, and that these compounds account for an even larger fraction of OC during stagnation events. A companion paper describes a method to further group speciate these XAD-8 isolated fractions.

  14. Microwave-assisted Extraction of Rare Earth Elements from Petroleum Refining Catalysts and Ambient Fine Aerosols Prior to Inductively Coupled Plasma - Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, David W.; Kulkarni, Pranav; Chellam, Shankar

    2006-01-01

    In the absence of a certified reference material, a robust microwave-assisted acid digestion procedure followed by inductively coupled plasma - mass spectrometry (ICP-MS) was developed to quantify rare earth elements (REEs) in fluidized-bed catalytic cracking (FCC) catalysts and atmospheric fine particulate matter (PM2.5). High temperature (200 C), high pressure (200 psig), acid digestion (HNO3, HF, and H3BO3) with 20 minute dwell time effectively solubilized REEs from six fresh catalysts, a spent catalyst, and PM2.5. This method was also employed to measure 27 non-REEs including Na, Mg, Al, Si, K, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Zr, Mo, Cd, Cs, Ba, Pb, and U. Complete extraction of several REEs (Y, La, Ce, Pr, Nd, Tb, Dy, and Er) required HF indicating that they were closely associated with the aluminosilicate structure of the zeolite FCC catalysts. Internal standardization using 115In quantitatively corrected non-spectral interferences in the catalyst digestate matrix. Inter-laboratory comparison using ICP-optical emission spectroscopy (ICP-OES) and instrumental neutron activation analysis (INAA) demonstrated the applicability of the newly developed analytical method for accurate analysis of REEs in FCC catalysts. The method developed for FCC catalysts was also successfully implemented to measure trace to ultra-trace concentrations of La, Ce, Pr, Nd, Sm, Gd, Eu, and Dy in ambient PM2.5 in an industrial area of Houston, TX.

  15. Microwave-assisted extraction of rare earth elements from petroleum refining catalysts and ambient fine aerosols prior to inductively coupled plasma-mass spectrometry.

    PubMed

    Kulkarni, Pranav; Chellam, Shankararaman; Mittlefehldt, David W

    2007-01-01

    A robust microwave-assisted acid digestion procedure followed by inductively coupled plasma-mass spectrometry (ICP-MS) was developed to quantify rare earth elements (REEs) in fluidized-bed catalytic cracking (FCC) catalysts and atmospheric fine particulate matter (PM(2.5)). High temperature (200 degrees C), high pressure (200 psig), acid digestion (HNO(3), HF and H(3)BO(3)) with 20 min dwell time effectively solubilized REEs from six fresh catalysts, a spent catalyst and PM(2.5). This method was also employed to measure 27 non-REEs including Na, Mg, Al, Si, K, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Zr, Mo, Cd, Cs, Ba, Pb and U. Complete extraction of several REEs (Y, La, Ce, Pr, Nd, Tb, Dy and Er) required HF indicating that they were closely associated with the aluminosilicate structure of the zeolite FCC catalysts. Internal standardization using (115)In quantitatively corrected non-spectral interferences in the catalyst digestate matrix. Inter-laboratory comparison using ICP-optical emission spectroscopy (ICP-OES) and instrumental neutron activation analysis (INAA) demonstrated the applicability of the newly developed analytical method for accurate analysis of REEs in FCC catalysts. The method developed for FCC catalysts was also successfully implemented to measure trace to ultra-trace concentrations of La, Ce, Pr, Nd, Sm, Gd, Eu and Dy in ambient PM(2.5) in an industrial area of Houston, TX. PMID:17386451

  16. The impact of changing surface ocean conditions on the dissolution of aerosol iron

    NASA Astrophysics Data System (ADS)

    Fishwick, Matthew P.; Sedwick, Peter N.; Lohan, Maeve C.; Worsfold, Paul J.; Buck, Kristen N.; Church, Thomas M.; Ussher, Simon J.

    2014-11-01

    The proportion of aerosol iron (Fe) that dissolves in seawater varies greatly and is dependent on aerosol composition and the physicochemical conditions of seawater, which may change depending on location or be altered by global environmental change. Aerosol and surface seawater samples were collected in the Sargasso Sea and used to investigate the impact of these changing conditions on aerosol Fe dissolution in seawater. Our data show that seawater temperature, pH, and oxygen concentration, within the range of current and projected future values, had no significant effect on the dissolution of aerosol Fe. However, the source and composition of aerosols had the most significant effect on the aerosol Fe solubility, with the most anthropogenically influenced samples having the highest fractional solubility (up to 3.2%). The impact of ocean warming and acidification on aerosol Fe dissolution is therefore unlikely to be as important as changes in land usage and fossil fuel combustion. Our experimental results also reveal important changes in the size distribution of soluble aerosol Fe in solution, depending on the chemical conditions of seawater. Under typical conditions, the majority (77-100%) of Fe released from aerosols into ambient seawater existed in the colloidal (0.02-0.4 µm) size fraction. However, in the presence of a sufficient concentration of strong Fe-binding organic ligands (10 nM) most of the aerosol-derived colloidal Fe was converted to soluble Fe (<0.02 µm). This finding highlights the potential importance of organic ligands in retaining aerosol Fe in a biologically available form in the surface ocean.

  17. Radiative Effects of Aerosols

    NASA Technical Reports Server (NTRS)

    Valero, Francisco P. J.

    1996-01-01

    During the Atlantic Stratocumulus Transition Experiment (ASTEX) in June 1992, two descents in cloud-free regions allowed comparison of the change in aerosol optical depth as determined by an onboard total-direct-diffuse radiometer (TDDR) to the change calculated from measured size-resolved aerosol microphysics and chemistry. Both profiles included a pollution haze from Europe but the second also included the effect of a Saharan dust layer above the haze. The separate contributions of supermicrometer (coarse) and submicrometer (fine) aerosol were determined and thermal analysis of the pollution haze indicated that the fine aerosol was composed primarily of a sulfate/water mixture with a refractory soot-like core. The soot core increased the calculated extinction by about 10% in the most polluted drier layer relative to a pure sulfate aerosol but had significantly less effect at higher humidities. A 3 km descent through a boundary layer air mass dominated by pollutant aerosol with relative humidities (RH) 10-77% yielded a close agreement between the measured and calculated aerosol optical depths (550 nm) of 0.160 (+/- 0.07) and 0. 157 (+/- 0.034) respectively. During descent the aerosol mass scattering coefficient per unit sulfate mass varied from about 5 to 16 m(exp 2)/g and primarily dependent upon ambient RH. However, the total scattering coefficient per total fine mass was far less variable at about 4+/- 0.7 m(exp 2)/g. A subsequent descent through a Saharan dust layer located above the pollution aerosol layer revealed that both layers contributed similarly to aerosol optical depth. The scattering per unit mass of the coarse aged dust was estimated at 1.1 +/- 0.2 m(exp 2)/g. The large difference (50%) in measured and calculated optical depth for the dust layer exceeded measurements.

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

    SciTech Connect

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

    1995-12-31

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

  19. Sugars in Antarctic aerosol

    NASA Astrophysics Data System (ADS)

    Barbaro, Elena; Kirchgeorg, Torben; Zangrando, Roberta; Vecchiato, Marco; Piazza, Rossano; Barbante, Carlo; Gambaro, Andrea

    2015-10-01

    The processes and transformations occurring in the Antarctic aerosol during atmospheric transport were described using selected sugars as source tracers. Monosaccharides (arabinose, fructose, galactose, glucose, mannose, ribose, xylose), disaccharides (sucrose, lactose, maltose, lactulose), alcohol-sugars (erythritol, mannitol, ribitol, sorbitol, xylitol, maltitol, galactitol) and anhydrosugars (levoglucosan, mannosan and galactosan) were measured in the Antarctic aerosol collected during four different sampling campaigns. For quantification, a sensitive high-pressure anion exchange chromatography was coupled with a single quadrupole mass spectrometer. The method was validated, showing good accuracy and low method quantification limits. This study describes the first determination of sugars in the Antarctic aerosol. The total mean concentration of sugars in the aerosol collected at the "Mario Zucchelli" coastal station was 140 pg m-3; as for the aerosol collected over the Antarctic plateau during two consecutive sampling campaigns, the concentration amounted to 440 and 438 pg m-3. The study of particle-size distribution allowed us to identify the natural emission from spores or from sea-spray as the main sources of sugars in the coastal area. The enrichment of sugars in the fine fraction of the aerosol collected on the Antarctic plateau is due to the degradation of particles during long-range atmospheric transport. The composition of sugars in the coarse fraction was also investigated in the aerosol collected during the oceanographic cruise.

  20. Aerosol Analysis via Electrostatic Precipitation-Electrospray Ionization Mass Spectrometry.

    PubMed

    He, Siqin; Li, Lin; Duan, Hongxu; Naqwi, Amir; Hogan, Christopher J

    2015-07-01

    Electrospray ionization (ESI) is the preferred mode of ion generation for mass analysis of many organic species, as alternative ionization techniques can lead to appreciable analyte fragmentation. For this reason, ESI is an ideal method for the analysis of species within aerosol particles. However, because of their low concentrations (∼10 μg/m(3)) in most environments, ESI has been applied sparingly in aerosol particle analysis; aerosol mass spectrometers typically employ analyte volatilization followed by electron ionization or chemical ionization, which can lead to a considerable degree of analyte fragmentation. Here, we describe an approach to apply ESI to submicrometer and nanometer scale aerosol particles, which utilizes unipolar ionization to charge particles, electrostatic precipitation to collect particles on the tip of a Tungsten rod, and subsequently, by flowing liquid over the rod, ESI and mass analysis of the species composing collected particles. This technique, which we term electrostatic precipitation-ESI-MS (EP-ESI-MS), is shown to enable analysis of nanogram quantities of collected particles (from aerosol phase concentrations as low as 10(2) ng m(-3)) composed of cesium iodide, levoglucosan, and levoglucosan within a carbon nanoparticle matrix. With EP-ESI-MS, the integrated mass spectrometric signals are found to be a monotonic function of the mass concentration of analyte in the aerosol phase. We additionally show that EP-ESI-MS has a dynamic range of close to 5 orders of magnitude in mass, making it suitable for molecular analysis of aerosol particles in laboratory settings with upstream particle size classification, as well as analysis of PM 2.5 particles in ambient air. PMID:26024017

  1. AEROSOL CHEMICAL CHARACTERISTION ON BOARD THE DOE G1 AIRCRAFT USING A PARTICLE INTO LIQUID SAMPLER DURING THE TEXAQS 2000 EXPERIMENT.

    SciTech Connect

    LEE,Y.N.; SONG,Z.; LIU,Y.; DAUM,P.; WEBER,R.; ORSINI,D.; LAULAINEN,N.; HUBBE,J.; MORRIS,V.

    2001-01-13

    Knowledge of aerosol chemical composition is key to understanding a number of properties of ambient aerosol particles including sources, size/number distribution, chemical evolution, optical properties and human health effects. Although filter based techniques have been widely used to determine aerosol chemical constituents, they generally cannot provide sufficiently fast time resolution needed to investigate sources and chemical evolution that effect aerosol chemical, size and number changes. In order to gain an ability to describe and predict the life cycles of ambient aerosols as a basis for ambient air quality control, fast and sensitive determination of the aerosol chemical composition must be made available. To help to achieve this goal, we deployed a newly developed technique, referred to as PILS (particle-into-liquid-sampler), on the DOE G1 aircraft during the 2000 Texas Air Quality Study (TexAQS 2000) to characterize the major ionic species of aerosol particles with aerodynamic size smaller than 2.5 {micro}m (PM 2.5). The results obtained are examined in the context of other simultaneously collected data for insights into the measurement capability of the PILS system.

  2. Intercomparison and closure calculations using measurements of aerosol species and optical properties during the Yosemite Aerosol Characterization Study

    NASA Astrophysics Data System (ADS)

    Malm, William C.; Day, Derek E.; Carrico, Christian; Kreidenweis, Sonia M.; Collett, Jeffrey L.; McMeeking, Gavin; Lee, Taehyoung; Carrillo, Jacqueline; Schichtel, Bret

    2005-07-01

    Physical and optical properties of inorganic aerosols have been extensively studied, but less is known about carbonaceous aerosols, especially as they relate to the non-urban settings such as our nation's national parks and wilderness areas. Therefore an aerosol characterization study was conceived and implemented at one national park that is highly impacted by carbonaceous aerosols, Yosemite. The primary objective of the study was to characterize the physical, chemical, and optical properties of a carbon-dominated aerosol, including the ratio of total organic matter weight to organic carbon, organic mass scattering efficiencies, and the hygroscopic characteristics of a carbon-laden ambient aerosol, while a secondary objective was to evaluate a variety of semi-continuous monitoring systems. Inorganic ions were characterized using 24-hour samples that were collected using the URG and Interagency Monitoring of Protected Visual Environments (IMPROVE) monitoring systems, the micro-orifice uniform deposit impactor (MOUDI) cascade impactor, as well as the semi-continuous particle-into-liquid sampler (PILS) technology. Likewise, carbonaceous material was collected over 24-hour periods using IMPROVE technology along with the thermal optical reflectance (TOR) analysis, while semi-continuous total carbon concentrations were measured using the Rupprecht and Patashnick (R&P) instrument. Dry aerosol number size distributions were measured using a differential mobility analyzer (DMA) and optical particle counter, scattering coefficients at near-ambient conditions were measured with nephelometers fitted with PM10 and PM2.5 inlets, and "dry" PM2.5 scattering was measured after passing ambient air through Perma Pure Nafion® dryers. In general, the 24-hour "bulk" measurements of various aerosol species compared more favorably with each other than with the semi-continuous data. Semi-continuous sulfate measurements correlated well with the 24-hour measurements, but were biased low by

  3. Lignin-derived phenols in Houston aerosols: implications for natural background sources.

    PubMed

    Shakya, Kabindra M; Louchouarn, Patrick; Griffin, Robert J

    2011-10-01

    Solvent-extractable monomeric methoxyphenols in aerosol samples conventionally have been used to indicate the influence of biomass combustion. In addition, the presence of lignin oxidation products (LOP), derived from the CuO oxidation of vascular plant organic matter, can help trace the source and inputs of primary biological particles in aerosols. Ambient aerosols (coarse and fine) collected in Houston during summer 2010 were analyzed by gas chromatography-mass spectrometry to characterize monomeric and polymeric sources of LOPs. This is the first time polymeric forms of the LOPs have been characterized in ambient aerosols. The absence or small concentrations of solvent-extractable monomeric LOPs and levoglucosan isomers point to the limited influence of biomass burning during the sampling period. The trace levels of anhydrosugar concentrations most likely result from long-range transport. This observation is supported by the absence of co-occurring lignin monomers that undergo photochemical degradation during transport. The larger concentration (142 ng m(-3)) of lignin polymers in coarse aerosols shows the relative importance of primary biological aerosol particles, even in the urban atmosphere. The LOP parameters suggest a predominant influence from woody tissue of angiosperms, with minor influence from soft tissues, gymnosperms, and soil organic matter.

  4. Ultrahigh resolution mass spectrometric characterization of organic aerosol from European and Chinese cities

    NASA Astrophysics Data System (ADS)

    Wang, Kai; Huang, Ru-Jin; Hoffmann, Thorsten

    2016-04-01

    Organic aerosol constitutes a substantial fraction (20-90%) of submicrometer aerosol mass, playing an important role in air quality and human health. Over the past few years, ultra-high resolution mass spectrometry (UHRMS) has been applied to elucidate the chemical composition of ambient aerosols. However, most of the UHRMS studies used direct infusion without prior separation by liquid chromatography, which may cause the loss of individual compound information and interference problems. In the present study, urban ambient aerosol with particle diameter < 2.5 μm was collected in Mainz, Germany and Beijing, China, respectively. Two pretreatment procedures were applied to extract the organic compounds from the filter samples: One method uses a mixture of acetonitrile and water, the other uses pure water and prepared for the extraction of humic-like substances. The extracts were analyzed by ultra-high-performance liquid chromatography coupled with an Orbitrap mass spectrometer in both negative and the positive modes. The effects of pretreatment procedures on the characterization of organic aerosol and the city-wise difference in chemical composition of organic aerosol will be discussed in detail.

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

    NASA Astrophysics Data System (ADS)

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

    2004-10-01

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

  6. Monitoring particulate carbon collected on Teflon filters: an evaluation of photoacoustic and transmission techniques.

    PubMed

    Bennett, C A; Patty, R R

    1982-02-01

    The Colorado State University Aerosol Workshop provided an excellent opportunity to obtain various particulate samples collected on filters. Our results indicate that the photoacoustic technique is preferable to the transmission technique (integrating plate method) for ambient samples with low-filter loadings since the presence of a nonabsorbing scattering aerosol (ammonium sulfate) only slightly perturbs the photoacoustic signal and significantly affects the transmitted signal. Measurements indicate that the photoacoustic signal depends not only on the energy absorbed from the incident beam but also on the existence of thermal wave interference effects and, especially for heavily loaded filters, on the presence of a nonabsorbing scattering aerosol. PMID:20372464

  7. In Situ Aerosol Optical Thickness Collected by the SIMBIOS Program (1997-2000): Protocols, and and Data QC and Analysis

    NASA Technical Reports Server (NTRS)

    Fargion, Giulietta S.; Barnes, Robert; McClain, Charles

    2001-01-01

    The purpose of this technical report is to provide current documentation of the Sensor Intercomparison and Merger for Biological and Interdisciplinary Oceanic Studies (SIMBIOS) Project Office activities on in situ aerosol optical thickness (i.e., protocols, and data QC and analysis). This documentation is necessary to ensure that critical information is related to the scientific community and NASA management. This critical information includes the technical difficulties and challenges of validating and combining ocean color data from an array of independent satellite systems to form consistent and accurate global bio-optical time series products. This technical report is not meant as a substitute for scientific literature. Instead, it will provide a ready and responsive vehicle for the multitude of technical reports issued by an operational project.

  8. Characterization and source apportionment of aerosol light extinction with a coupled model of CMB-IMPROVE in Hangzhou, Yangtze River Delta of China

    NASA Astrophysics Data System (ADS)

    Wang, Jiao; Zhang, Yu-fen; Feng, Yin-chang; Zheng, Xian-jue; Jiao, Li; Hong, Sheng-mao; Shen, Jian-dong; Zhu, Tan; Ding, Jing; Zhang, Qi

    2016-09-01

    To investigate the characteristics and sources of aerosol light extinction in the Yangtze River Delta of China, a campaign was carried out in Hangzhou from December 2013 to November 2014. Hourly data for air pollutants including PM2.5, SO2, NO2, O3 and CO, and aerosol optical properties including aerosol scattering coefficient and aerosol absorbing coefficient was obtained in the environmental air quality automatic monitoring station. Meteorological parameters were measured synchronously in the automated meteorology monitoring station. Additionally, around seven sets of ambient PM2.5 samples per month were collected and analyzed during the campaign. The annual mean aerosol scattering coefficient, aerosol absorbing coefficient and aerosol single scattering albedo measured in this study was 514 ± 284 Mm- 1, 35 ± 20 Mm- 1 and 94% respectively. The aerosol extinction coefficient reconstructed using the modified IMPROVE (Interagency Monitoring of Protected Visual Environment) formula was compared to the measured extinction coefficient. Better correlations could be found between the measured and reconstructed extinction coefficient when RH was under 90%. A coupled model of CMB (chemical mass balance) and modified IMPROVE was used to apportion the sources of aerosol light extinction in Hangzhou. Vehicle exhaust, secondary nitrate and secondary sulfate were identified as the most significant sources for aerosol light extinction, accounted for 30.2%, 24.1% and 15.8% respectively.

  9. Thermal relaxation and collective dynamics of interacting aerosol-generated hexagonal NiFe2O4 nanoparticles.

    PubMed

    Ortega, D; Kuznetsov, M V; Morozov, Yu G; Belousova, O V; Parkin, I P

    2013-12-28

    This article reports on the magnetic properties of interacting uncoated nickel ferrite (NiFe2O4) nanoparticles synthesized through an aerosol levitation-jet technique. A comprehensive set of samples with different compositions of background gas and metal precursors, as well as applied electric field intensities, has been studied. Nanoparticles prepared under a field of 210 kV m(-1) show moderately high-field irreversibility and shifted hysteresis loops after field-cooling, also exhibiting a joint temperature decrease of the exchange field and coercivity. The appearance of memory effects has been checked using the genuine ZFC protocol and the observed behavior cannot be fully explained in terms of thermal relaxation. Although dipolar interactions prevail, exchange interactions occur to a certain extent within a narrow range of applied fields. The origin of the slow dynamics in the system is found to be given by the interplay of the distribution of energy barriers due to size dispersion and the cooperative dynamics associated with frustrated interactions. PMID:24196451

  10. Review of Trace-Element Field-Blank Data Collected for the California Groundwater Ambient Monitoring and Assessment (GAMA) Program, May 2004-January 2008

    USGS Publications Warehouse

    Olsen, Lisa D.; Fram, Miranda S.; Belitz, Kenneth

    2010-01-01

    Trace-element quality-control samples (for example, source-solution blanks, field blanks, and field replicates) were collected as part of a statewide investigation of groundwater quality in California, known as the Priority Basins Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The GAMA Priority Basins Project is being conducted by the U.S. Geological Survey (USGS) in cooperation with the California State Water Resources Control Board (SWRCB) to assess and monitor the quality of groundwater resources used for drinking-water supply and to improve public knowledge of groundwater quality in California. Trace-element field blanks were collected to evaluate potential bias in the corresponding environmental data. Bias in the environmental data could result from contamination in the field during sample collection, from the groundwater coming into contact with contaminants on equipment surfaces or from other sources, or from processing, shipping, or analyzing the samples. Bias affects the interpretation of environmental data, particularly if any constituents are present solely as a result of extrinsic contamination that would have otherwise been absent from the groundwater that was sampled. Field blanks were collected, analyzed, and reviewed to identify and quantify extrinsic contamination bias. Data derived from source-solution blanks and laboratory quality-control samples also were considered in evaluating potential contamination bias. Eighty-six field-blank samples collected from May 2004 to January 2008 were analyzed for the concentrations of 25 trace elements. Results from these field blanks were used to interpret the data for the 816 samples of untreated groundwater collected over the same period. Constituents analyzed were aluminum (Al), antimony (Sb), arsenic (As), barium (Ba), beryllium (Be), boron (B), cadmium (Cd), chromium (Cr), cobalt (Co), copper (Cu), iron (Fe), lead (Pb), lithium (Li), manganese (Mn), mercury (Hg), molybdenum

  11. Chemical characterization of individual particles and residuals of cloud droplets and ice crystals collected on board research aircraft in the ISDAC 2008 study

    NASA Astrophysics Data System (ADS)

    Hiranuma, N.; Brooks, S. D.; Moffet, R. C.; Glen, A.; Laskin, A.; Gilles, M. K.; Liu, P.; MacDonald, A. M.; Strapp, J. W.; McFarquhar, G. M.

    2013-06-01

    Ambient particles and the dry residuals of mixed-phase cloud droplets and ice crystals were collected during the Indirect and Semi-Direct Aerosol Campaign (ISDAC) near Barrow, Alaska, in spring of 2008. The collected particles were analyzed using Computer Controlled Scanning Electron Microscopy with Energy Dispersive X-ray analysis and Scanning Transmission X-ray Microscopy coupled with Near Edge X-ray Absorption Fine Structure spectroscopy to identify physico-chemical properties that differentiate cloud-nucleating particles from the total aerosol population. A wide range of individually mixed components was identified in the ambient particles and residuals including organic carbon compounds, inorganics, carbonates, and black carbon. Our results show that cloud droplet residuals differ from the ambient particles in both size and composition, suggesting that both properties may impact the cloud-nucleating ability of aerosols in mixed-phase clouds. The percentage of residual particles which contained carbonates (47%) was almost four times higher than those in ambient samples. Residual populations were also enhanced in sea salt and black carbon and reduced in organic compounds relative to the ambient particles. Further, our measurements suggest that chemical processing of aerosols may improve their cloud-nucleating ability. Comparison of results for various time periods within ISDAC suggests that the number and composition of cloud-nucleating particles over Alaska can be influenced by episodic events bringing aerosols from both the local vicinity and as far away as Siberia.

  12. Ergosterol, arabitol and manitol as tracers for biological aerosols

    NASA Astrophysics Data System (ADS)

    Rudich, Y.; Burshtein, N.; Lang-Yona, N.

    2010-12-01

    Airborne fungi can cause a wide array of adverse responses in humans depending on the type and quantity present. Since dose and human response is highly individual, the sensitivity of a person exposed is also an important consideration. The abundance of bioaerosols in the ambient air and their health impacts depend on the season and on the environmental conditions. In order to quantify and identify fungi bioaerosols’ contribution to atmospheric aerosols and the impact to public health, it has been suggested to use chemicals that are typical of bioaerosols as biomarkers in chemical analysis of collected aerosols. An often used biomarker for determining the fungal biomass is ergosterol. Recently, Bauer et al. (2008) found that mannitol and arabitol concentrations are correlated with the fungal spore counts in atmospheric PM10. In this study, ergosterol, arabitol and mannitol were quantified in ambient aerosols collected in the Eastern Mediterranean region for 12 months in order to understand their annual and seasonal behavior and to test whether arabitol and mannitol are good predictors of fungi. Finally, correlations between ergosterol abundances with inorganic ions, humidity, temperature, and synoptic data in order to identify dominant sources of fungal spores were also studied. We will report on the measurements and the observed correlations between the different tracers.

  13. Identification of source contributions to visibility-reducing organic aerosols in the vicinity of Grand Canyon National Park. Interim final report

    SciTech Connect

    Mazurek, M.A.; Hallock, K.A.; Leach, M.; Mason-Jones, M.; Mason-Jones, H.; Salmon, L.G.; Winner, D.A.; Cass, G.R.

    1993-06-01

    Sulfates and carbonaceous aerosols are the largest contributors to the fine particle burden in the atmosphere near Grand Canyon National Park. While the effects of sulfate particles on visibility at the Grand Canyon has been extensively studied, much less is known about the nature and origin of the carbonaceous aerosols that are present. This disparity in understanding arises from at least two causes: aerosol carbon data for the region are less plentiful and many of the sources that could contribute to that organic aerosol are both diverse and not well characterized. The objective of this present study is to examine the origin of the carbonaceous aerosol at Grand Canyon National Park during the summer season based on molecular tracer techniques applied to source and ambient samples collected specifically for this purpose.

  14. Characterization and source apportionment of organic aerosol using offline aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    Daellenbach, K. R.; Bozzetti, C.; Křepelová, A.; Canonaco, F.; Wolf, R.; Zotter, P.; Fermo, P.; Crippa, M.; Slowik, J. G.; Sosedova, Y.; Zhang, Y.; Huang, R.-J.; Poulain, L.; Szidat, S.; Baltensperger, U.; Prévôt, A. S. H.; El Haddad, I.

    2015-08-01

    Field deployments of the Aerodyne Aerosol Mass Spectrometer (AMS) have significantly advanced real-time measurements and source apportionment of non-refractory particulate matter. However, the cost and complex maintenance requirements of the AMS make impractical its deployment at sufficient sites to determine regional characteristics. Furthermore, the negligible transmission efficiency of the AMS inlet for supermicron particles significantly limits the characterization of their chemical nature and contributing sources. In this study, we utilize the AMS to characterize the water-soluble organic fingerprint of ambient particles collected onto conventional quartz filters, which are routinely sampled at many air quality sites. The method was applied to 256 particulate matter (PM) filter samples (PM1, PM2.5, PM10) collected at 16 urban and rural sites during summer and winter. We show that the results obtained by the present technique compare well with those from co-located online measurements, e.g. AMS or Aerosol Chemical Speciation Monitor (ACSM). The bulk recoveries of organic aerosol (60-91 %) achieved using this technique, together with low detection limits (0.8 μg of organic aerosol on the analyzed filter fraction) allow its application to environmental samples. We will discuss the recovery variability of individual hydrocarbon, oxygen containing and other ions. The performance of such data in source apportionment is assessed in comparison to ACSM data. Recoveries of organic components related to different sources as traffic, wood burning and secondary organic aerosol are presented. This technique, while subjected to the limitations inherent to filter-based measurements (e.g. filter artifacts and limited time resolution) may be used to enhance the AMS capabilities in measuring size-fractionated, spatially-resolved long-term datasets.

  15. Characterization and source apportionment of organic aerosol using offline aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    Daellenbach, K. R.; Bozzetti, C.; Křepelová, A.; Canonaco, F.; Wolf, R.; Zotter, P.; Fermo, P.; Crippa, M.; Slowik, J. G.; Sosedova, Y.; Zhang, Y.; Huang, R.-J.; Poulain, L.; Szidat, S.; Baltensperger, U.; El Haddad, I.; Prévôt, A. S. H.

    2016-01-01

    Field deployments of the Aerodyne Aerosol Mass Spectrometer (AMS) have significantly advanced real-time measurements and source apportionment of non-refractory particulate matter. However, the cost and complex maintenance requirements of the AMS make its deployment at sufficient sites to determine regional characteristics impractical. Furthermore, the negligible transmission efficiency of the AMS inlet for supermicron particles significantly limits the characterization of their chemical nature and contributing sources. In this study, we utilize the AMS to characterize the water-soluble organic fingerprint of ambient particles collected onto conventional quartz filters, which are routinely sampled at many air quality sites. The method was applied to 256 particulate matter (PM) filter samples (PM1, PM2.5, and PM10, i.e., PM with aerodynamic diameters smaller than 1, 2.5, and 10 µm, respectively), collected at 16 urban and rural sites during summer and winter. We show that the results obtained by the present technique compare well with those from co-located online measurements, e.g., AMS or Aerosol Chemical Speciation Monitor (ACSM). The bulk recoveries of organic aerosol (60-91 %) achieved using this technique, together with low detection limits (0.8 µg of organic aerosol on the analyzed filter fraction) allow its application to environmental samples. We will discuss the recovery variability of individual hydrocarbon ions, ions containing oxygen, and other ions. The performance of such data in source apportionment is assessed in comparison to ACSM data. Recoveries of organic components related to different sources as traffic, wood burning, and secondary organic aerosol are presented. This technique, while subjected to the limitations inherent to filter-based measurements (e.g., filter artifacts and limited time resolution) may be used to enhance the AMS capabilities in measuring size-fractionated, spatially resolved long-term data sets.

  16. Direct gravimetric measurements of the mass of the antarctic aerosol collected by high volume sampler: PM10 summer seasonal variation at Terra Nova Bay.

    PubMed

    Truzzi, Cristina; Lambertucci, Luca; Illuminati, Silvia; Annibaldi, Anna; Scarponi, Giuseppe

    2005-01-01

    An on-site procedure was set up for direct gravimetric measurement of the mass of aerosol collected using high volume impactors (aerodynamic size cut point of 10 microm, PM10); this knowledge has hitherto been unavailable. Using a computerized microbalance in a clean chemistry laboratory, under controlled temperature (+/-0.5 degrees C) and relative humidity (+/-1%), continuous, long time filter mass measurements (hours) were carried out before and after exposure, after a 48 h minimun equilibration at the laboratory conditions. The effect of the electrostatic charge was exhausted in 30-60 min, after which stable measurements were obtained. Measurements of filters exposed for 7-11 days (1.13 m3 min(-1)) in a coastal site near Terra Nova Bay (December 2000 - February 2001), gave results for aerosol mass in the order of 10-20 mg (SD approximately 2 mg), corresponding to atmospheric concentrations of 0.52-1.27 microg m(-3). Data show a seasonal behaviour in the PM10 content with an increase during December - early January, followed by a net decrease. The above results compare well with estimates obtained from proxy data for the Antarctic Peninsula (0.30 microg m(-3)), the Ronne Ice Shelf (1.49 microg m(-3)), and the South Pole (0.18 microg m(-3), summer 1974-1975, and 0.37 microg m(-3), average summer seasons 1975-1976 and 1977-1978), and from direct gravimetric measurements recently obtained from medium volume samplers at McMurdo station (downwind 3.39 microg m(-3), upwind 4.15 microg m(-3)) and at King George Island (2.5 microg m(-3), summer, particle diameter <20 microm). This finding opens the way to the direct measurement of the chemical composition of the Antarctic aerosol and, in turn, to a better knowledge of the snow/air relationships as required for the reconstruction of the chemical composition of past atmospheres from deep ice core data.

  17. Direct gravimetric measurements of the mass of the antarctic aerosol collected by high volume sampler: PM10 summer seasonal variation at Terra Nova Bay.

    PubMed

    Truzzi, Cristina; Lambertucci, Luca; Illuminati, Silvia; Annibaldi, Anna; Scarponi, Giuseppe

    2005-01-01

    An on-site procedure was set up for direct gravimetric measurement of the mass of aerosol collected using high volume impactors (aerodynamic size cut point of 10 microm, PM10); this knowledge has hitherto been unavailable. Using a computerized microbalance in a clean chemistry laboratory, under controlled temperature (+/-0.5 degrees C) and relative humidity (+/-1%), continuous, long time filter mass measurements (hours) were carried out before and after exposure, after a 48 h minimun equilibration at the laboratory conditions. The effect of the electrostatic charge was exhausted in 30-60 min, after which stable measurements were obtained. Measurements of filters exposed for 7-11 days (1.13 m3 min(-1)) in a coastal site near Terra Nova Bay (December 2000 - February 2001), gave results for aerosol mass in the order of 10-20 mg (SD approximately 2 mg), corresponding to atmospheric concentrations of 0.52-1.27 microg m(-3). Data show a seasonal behaviour in the PM10 content with an increase during December - early January, followed by a net decrease. The above results compare well with estimates obtained from proxy data for the Antarctic Peninsula (0.30 microg m(-3)), the Ronne Ice Shelf (1.49 microg m(-3)), and the South Pole (0.18 microg m(-3), summer 1974-1975, and 0.37 microg m(-3), average summer seasons 1975-1976 and 1977-1978), and from direct gravimetric measurements recently obtained from medium volume samplers at McMurdo station (downwind 3.39 microg m(-3), upwind 4.15 microg m(-3)) and at King George Island (2.5 microg m(-3), summer, particle diameter <20 microm). This finding opens the way to the direct measurement of the chemical composition of the Antarctic aerosol and, in turn, to a better knowledge of the snow/air relationships as required for the reconstruction of the chemical composition of past atmospheres from deep ice core data. PMID:16398350

  18. Apportionment of Primary and Secondary Organic Aerosols in Southern California During the 2005 Study of Organic Aerosols in Riverside (SOAR-1)

    EPA Science Inventory

    Ambient sampling was conducted in Riverside, California during the 2005 Study of Organic Aerosols in Riverside to characterize the composition and sources of organic aerosol using a variety of state-of-the-art instrumentation and source apportionment techniques.

  19. Hourly In-Situ Measurements of Organic Aerosol Speciation by Thermal desorption Aerosol GC/MS-FID (TAG): Advances in Calibration Procedures

    NASA Astrophysics Data System (ADS)

    Kreisberg, N. M.; Williams, B. J.; Goldstein, A. H.; Hering, S. V.

    2005-12-01

    Thermal desorption Aerosol GC/MS-FID (TAG) provides a novel means of obtaining hourly in-situ measurements of organic aerosol speciation. In a typical chromatogram, hundreds to thousands of organic compounds may be present, making careful compound identification and calibration practices a critical part of obtaining reliable and useful data. This presentation will focus on a series of field calibrations performed during sampling of ambient aerosols using the TAG instrument. TAG couples inertial collection of fine particulates with diameters between 0.1 and 2.5 μm and analysis via gas phase chromatography and mass spectrometry following thermal desorption of a sample. This combined collection and analysis system provides hourly speciation of a wide range of organic compounds that is limited only by the compatibility of the GC column (DB-5MS) and feasible temperature range (50-300 °C). The direct introduction of thermally desorbed species into the GC/MS-FID avoids sample handling artifact concerns and costly analytical sample processing. A modified collection cell was introduced to the system that allows direct, in-situ injections of compound standards to calibrate and monitor the performance of the instrument. An evaluation of this approach is presented using results from UC Berkeley laboratory studies and a 5 week urban aerosol study in Riverside, California conducted July-August, 2005 as part of the Study of Organic Aerosols in Riverside (SOAR) campaign. Examples are given where the retention times of a large selection of compounds used as injection standards assisted in the positive identification and quantitation of organic species in ambient aerosols.

  20. Oxidation enhancement of submicron organic aerosols by fog processing

    NASA Astrophysics Data System (ADS)

    Zhang, Q.; Ge, X.; Collier, S.; Setyan, A.; Xu, J.; Sun, Y.

    2011-12-01

    During 2010 wintertime, a measurement study was carried out at Fresno, California, using an Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) combined with a Scanning Mobility Particle Sizer (SMPS). Four fog events occurred during the first week of the campaign. While ambient aerosol was sampled into the HR-ToF-AMS, fog water samples were collected, and were later aerosolized and analyzed via HR-TOF-AMS in the laboratory. We performed Positive Matrix Factorization (PMF) on the AMS ambient organic mass spectra, and identified four OA factors: hydrocarbon-like OA (HOA) likely from vehicle emissions, cooking influenced OA (COA), biomass burning OA (BBOA) representing residential wood combustion, and an oxygenated OA (OOA) that has an average O/C ratio of 0.42. The time series of the OOA factor correlates best with that of sulfate (R2 =0.54 ) during fog events, suggesting that aqueous phase processing may have strongly affected OOA production during wintertime in Fresno. We further investigate the OOA compositions and elemental ratios before, during, and after the fog events, as well as those of dissolved organic matter (DOM) in fog waters to study the influence of aqueous phase processing on OA compositions. Results of fog sample analysis shows an enhancement of oxidation of DOM in 11 separate fog samples. Further factor analysis of the fog DOM data will elucidate the possible mechanisms by which fog processing enhances oxidation of aerosol. In addition, in order to investigate the influence of aqueous processing on OA, we used the Extended Aerosol Inorganic Model (E-AIM) (http://www.aim.env.uea.ac.uk/aim/aim.php) to estimate aerosol phase water contents based on the AMS measured aerosol composition. The predicted water content has a good correlation with sulfate and OOA . We will further explore the correlations between particle phase water with organic aerosol characteristics to discuss the influence of aqueous phase processing on

  1. Radioactive Aerosols as an Index of Air Pollution in the City of Thessaloniki, Greece

    SciTech Connect

    Ioannidou, A.; Papastefanou, C.

    2010-01-21

    This study summarizes results of an investigation done in order to find out how the radioactive aerosols of {sup 7}Be could serve as indicators of air pollution conditions. Beryllium-7 is a cosmic-ray produced radionuclide with an important fraction of its production to take place in the upper troposphere. Once it is formed is rapidly associated with submicron aerosol particles and participates in the formation and growth of the accumulation mode aerosols, which is a major reservoir of pollutants in the atmosphere. In order to define any influence of AMAD of {sup 7}Be aerosols by air pollution conditions, the aerodynamic size distribution of {sup 7}Be aerosols was determined by collecting samples at different locations in the suburban area of the city of Thessaloniki, including rural areas, industrial areas, high elevations, marine environment and the airport area. The aerodynamic size distribution of {sup 7}Be aerosols in different locations was obtained by using Andersen 1-ACFM cascade impactors and the Activity Median Aerodynamic Diameter (AMAD) was determined. Some dependency of the AMADs on height has been observed, while in near marine environment the {sup 7}Be activity size distribution was dominant in the upper size range of aerosol particles. Low AMADs as low as 0.62 to 0.74 {mu}m of {sup 7}Be aerosols have been observed at locations characterized with relative low pollution, while it is concluded that in the activity size distribution of ambient aerosols, {sup 7}Be changes to larger particle sizes in the presence of pollutants, since low AMADs of {sup 7}Be aerosols have been observed at low polluted locations. Preliminary data of simultaneous measurements of {sup 214}Pb and {sup 212}Pb with gaseous air pollutants CO, NO, NO{sub X}, SO{sub 2} and total suspended particulate matter (TSP) show that radon decay products near the ground could be a useful index of air pollution potential conditions and transport processes in the boundary layer.

  2. Updated study reporting levels (SRLs) for trace-element data collected for the California Groundwater Ambient Monitoring and Assessment (GAMA) Priority Basin Project, October 2009-March 2013

    USGS Publications Warehouse

    Davis, Tracy A.; Olsen, Lisa D.; Fram, Miranda S.; Belitz, Kenneth

    2014-01-01

    Groundwater samples have been collected in California as part of statewide investigations of groundwater quality conducted by the U.S. Geological Survey for the Groundwater Ambient Monitoring and Assessment (GAMA) Priority Basin Project (PBP). The GAMA-PBP is being conducted in cooperation with the California State Water Resources Control Board to assess and monitor the quality of groundwater resources used for drinking-water supply and to improve public knowledge of groundwater quality in California. Quality-control samples (source-solution blanks, equipment blanks, and field blanks) were collected in order to ensure the quality of the groundwater sample results. Olsen and others (2010) previously determined study reporting levels (SRLs) for trace-element results based primarily on field blanks collected in California from May 2004 through January 2008. SRLs are raised reporting levels used to reduce the likelihood of reporting false detections attributable to contamination bias. The purpose of this report is to identify any changes in the frequency and concentrations of detections in field blanks since the last evaluation and update the SRLs for more recent data accordingly. Constituents analyzed were aluminum (Al), antimony (Sb), arsenic (As), barium (Ba), beryllium (Be), boron (B), cadmium (Cd), chromium (Cr), cobalt (Co), copper (Cu), iron (Fe), lead (Pb), lithium (Li), manganese (Mn), molybdenum (Mo), nickel (Ni), selenium (Se), silver (Ag), strontium (Sr), thallium (Tl), tungsten (W), uranium (U), vanadium (V), and zinc (Zn). Data from 179 field blanks and equipment blanks collected from March 2006 through March 2013 by the GAMA-PBP indicated that for trace elements that had a change in detection frequency and concentration since the previous review, the shift occurred near October 2009, in conjunction with a change in the capsule filters used by the study. Results for 89 field blanks and equipment blanks collected from October 2009 through March 2013 were

  3. Chemical Characterization of Secondary Organic Aerosol from Oxidation of Isoprene Hydroxyhydroperoxides.

    PubMed

    Riva, Matthieu; Budisulistiorini, Sri H; Chen, Yuzhi; Zhang, Zhenfa; D'Ambro, Emma L; Zhang, Xuan; Gold, Avram; Turpin, Barbara J; Thornton, Joel A; Canagaratna, Manjula R; Surratt, Jason D

    2016-09-20

    Atmospheric oxidation of isoprene under low-NOx conditions leads to the formation of isoprene hydroxyhydroperoxides (ISOPOOH). Subsequent oxidation of ISOPOOH largely produces isoprene epoxydiols (IEPOX), which are known secondary organic aerosol (SOA) precursors. Although SOA from IEPOX has been previously examined, systematic studies of SOA characterization through a non-IEPOX route from 1,2-ISOPOOH oxidation are lacking. In the present work, SOA formation from the oxidation of authentic 1,2-ISOPOOH under low-NOx conditions was systematically examined with varying aerosol compositions and relative humidity. High yields of highly oxidized compounds, including multifunctional organosulfates (OSs) and hydroperoxides, were chemically characterized in both laboratory-generated SOA and fine aerosol samples collected from the southeastern U.S. IEPOX-derived SOA constituents were observed in all experiments, but their concentrations were only enhanced in the presence of acidified sulfate aerosol, consistent with prior work. High-resolution aerosol mass spectrometry (HR-AMS) reveals that 1,2-ISOPOOH-derived SOA formed through non-IEPOX routes exhibits a notable mass spectrum with a characteristic fragment ion at m/z 91. This laboratory-generated mass spectrum is strongly correlated with a factor recently resolved by positive matrix factorization (PMF) of aerosol mass spectrometer data collected in areas dominated by isoprene emissions, suggesting that the non-IEPOX pathway could contribute to ambient SOA measured in the Southeastern United States. PMID:27466979

  4. Long-term (2002-2014) evolution and trend in Collection 5.1 Level-2 aerosol products derived from the MODIS and MISR sensors over the Chinese Yangtze River Delta

    NASA Astrophysics Data System (ADS)

    Kang, Na; Kumar, K. Raghavendra; Hu, Kang; Yu, Xingna; Yin, Yan

    2016-11-01

    The present study aims to investigate spatio-temporal evolution and trend in the aerosol optical properties (aerosol optical depth, AOD; Ångström exponent, AE), qualitatively identify different types and origin of aerosols over an urban city, Nanjing in the Yangtze River Delta, East China. For this purpose, the Collection 5.1 Level-2 data obtained from the Moderate resolution Imaging Spectroradiometer (MODIS) sensor onboard Terra and Aqua satellites and the Multi-angle Imaging Spectroradiometer (MISR) instrument for the period between 2002 and 2014 have been analyzed. An inter-comparison and validation of AOD were performed against the AOD measurements obtained from the ground-based Aerosol Robotic Network (AERONET) sunphotometer. The MODIS AOD550 exhibited wide spatial and temporal distributions over East China, while MISR AOD555 was consistently lower than that of Terra and Aqua AOD550 values. The temporal variations (monthly and seasonal mean) of MODIS (Terra and Aqua) and MISR AOD values exhibited a similar pattern. The seasonal mean AOD550 (AE470-660) was found to be maximum with 0.97 ± 0.48 during summer (1.16 ± 0.33 in summer) and a minimum of 0.61 ± 0.28 during the winter season (0.80 ± 0.28 in spring). The annual mean Terra AOD550 at Nanjing showed a strong decreasing trend (- 0.70% year- 1), while the Aqua exhibited a slight increasing trend (+ 0.01 year- 1) during the study period. Seasonal air mass back-trajectories obtained from the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model were also computed to infer on the transport component over the study region. Different aerosol types were identified via the relationship between AOD550 and fine mode fraction, which reveals that the biomass burning/urban-industrial type aerosols (desert dust) are abundant over the region in summer (spring), apart from the mixed aerosol type.

  5. Organosulfates as Tracers for Secondary Organic Aerosol (SOA) Formation from 2-Methyl-3-Buten-2-ol (MBO) in the Atmosphere

    PubMed Central

    2012-01-01

    2-Methyl-3-buten-2-ol (MBO) is an important biogenic volatile organic compound (BVOC) emitted by pine trees and a potential precursor of atmospheric secondary organic aerosol (SOA) in forested regions. In the present study, hydroxyl radical (OH)-initiated oxidation of MBO was examined in smog chambers under varied initial nitric oxide (NO) and aerosol acidity levels. Results indicate measurable SOA from MBO under low-NO conditions. Moreover, increasing aerosol acidity was found to enhance MBO SOA. Chemical characterization of laboratory-generated MBO SOA reveals that an organosulfate species (C5H12O6S, MW 200) formed and was substantially enhanced with elevated aerosol acidity. Ambient fine aerosol (PM2.5) samples collected from the BEARPEX campaign during 2007 and 2009, as well as from the BEACHON-RoMBAS campaign during 2011, were also analyzed. The MBO-derived organosulfate characterized from laboratory-generated aerosol was observed in PM2.5 collected from these campaigns, demonstrating that it is a molecular tracer for MBO-initiated SOA in the atmosphere. Furthermore, mass concentrations of the MBO-derived organosulfate are well correlated with MBO mixing ratio, temperature, and acidity in the field campaigns. Importantly, this compound accounted for an average of 0.25% and as high as 1% of the total organic aerosol mass during BEARPEX 2009. An epoxide intermediate generated under low-NO conditions is tentatively proposed to produce MBO SOA. PMID:22849588

  6. Updated study reporting levels (SRLs) for trace-element data collected for the California Groundwater Ambient Monitoring and Assessment (GAMA) Priority Basin Project, October 2009-March 2013

    USGS Publications Warehouse

    Davis, Tracy A.; Olsen, Lisa D.; Fram, Miranda S.; Belitz, Kenneth

    2014-01-01

    Groundwater samples have been collected in California as part of statewide investigations of groundwater quality conducted by the U.S. Geological Survey for the Groundwater Ambient Monitoring and Assessment (GAMA) Priority Basin Project (PBP). The GAMA-PBP is being conducted in cooperation with the California State Water Resources Control Board to assess and monitor the quality of groundwater resources used for drinking-water supply and to improve public knowledge of groundwater quality in California. Quality-control samples (source-solution blanks, equipment blanks, and field blanks) were collected in order to ensure the quality of the groundwater sample results. Olsen and others (2010) previously determined study reporting levels (SRLs) for trace-element results based primarily on field blanks collected in California from May 2004 through January 2008. SRLs are raised reporting levels used to reduce the likelihood of reporting false detections attributable to contamination bias. The purpose of this report is to identify any changes in the frequency and concentrations of detections in field blanks since the last evaluation and update the SRLs for more recent data accordingly. Constituents analyzed were aluminum (Al), antimony (Sb), arsenic (As), barium (Ba), beryllium (Be), boron (B), cadmium (Cd), chromium (Cr), cobalt (Co), copper (Cu), iron (Fe), lead (Pb), lithium (Li), manganese (Mn), molybdenum (Mo), nickel (Ni), selenium (Se), silver (Ag), strontium (Sr), thallium (Tl), tungsten (W), uranium (U), vanadium (V), and zinc (Zn). Data from 179 field blanks and equipment blanks collected from March 2006 through March 2013 by the GAMA-PBP indicated that for trace elements that had a change in detection frequency and concentration since the previous review, the shift occurred near October 2009, in conjunction with a change in the capsule filters used by the study. Results for 89 field blanks and equipment blanks collected from October 2009 through March 2013 were

  7. Determination of Water Soluble Organic Carbon Collected ~1 km above the Earth's Surface during a Mid-Atlantic Air Quality Episode and Comparison to Aerosol Optical Properties

    NASA Astrophysics Data System (ADS)

    Brent, L. C.; He, H.; Arkinson, H. L.; Stehr, J. W.; Ring, A.; Marufu, L.; Reiner, J.; Sander, L. C.; Dickerson, R. R.

    2014-12-01

    Routine, light aircraft air-monitoring conducted in MD provides insight into atmospheric photochemical processing as a function of altitude in the boundary layer and lower free troposphere. We present correlations between the optical properties and chemical composition of aerosols at ~1 km altitude over Maryland. Data were collected during the peak smog day and a dissipation day during an air quality episode studied in DISCOVER-AQ, July 2011. Post flight filter sample analysis shows a positive trend between measurable carboxylate concentrations and particle size with a recirculating, aged, urban air mass influenced with southeasterly marine winds (peak day). A westerly influx of air from the Ohio River Valley on the dissipation day was depleted in carboxylates compared with samples collected over the same location two days prior. These samples contained quantifiable concentrations of cis-pinonic acid, a reaction product of pinene after ozonation and photochemical oxidation. New techniques were developed to improve airborne data collection and analysis of water soluble organic acids (WSOA), a frequently dominant fraction of particulate matter (PM). An ion chromatographic mass spectrometric method was developed using NIST Standard Referencing Material 1649b, Urban Dust, as a surrogate material to achieve separation and resolution of at least 34 organic acids. Analysis of aircraft filter samples resulted in detection of 16 organic acids of which 12 were quantified. Eight inorganic species were also quantified. Aged, re-circulated metropolitan air showed a greater number of dicarboxylic acids than new transport air from the west and may provide a useful test of SOA formation theory.

  8. Organic aerosols

    SciTech Connect

    Penner, J.E.

    1994-01-01

    Organic aerosols scatter solar radiation. They may also either enhance or decrease concentrations of cloud condensation nuclei. This paper summarizes observed concentrations of aerosols in remote continental and marine locations and provides estimates for the sources of organic aerosol matter. The anthropogenic sources of organic aerosols may be as large as the anthropogenic sources of sulfate aerosols, implying a similar magnitude of direct forcing of climate. The source estimates are highly uncertain and subject to revision in the future. A slow secondary source of organic aerosols of unknown origin may contribute to the observed oceanic concentrations. The role of organic aerosols acting as cloud condensation nuclei (CCN) is described and it is concluded that they may either enhance or decrease the ability of anthropogenic sulfate aerosols to act as CCN.

  9. Sampling strategies and post-processing methods for increasing the time resolution of organic aerosol measurements requiring long sample-collection times

    NASA Astrophysics Data System (ADS)

    Modini, Rob L.; Takahama, Satoshi

    2016-07-01

    The composition and properties of atmospheric organic aerosols (OAs) change on timescales of minutes to hours. However, some important OA characterization techniques typically require greater than a few hours of sample-collection time (e.g., Fourier transform infrared (FTIR) spectroscopy). In this study we have performed numerical modeling to investigate and compare sample-collection strategies and post-processing methods for increasing the time resolution of OA measurements requiring long sample-collection times. Specifically, we modeled the measurement of hydrocarbon-like OA (HOA) and oxygenated OA (OOA) concentrations at a polluted urban site in Mexico City, and investigated how to construct hourly resolved time series from samples collected for 4, 6, and 8 h. We modeled two sampling strategies - sequential and staggered sampling - and a range of post-processing methods including interpolation and deconvolution. The results indicated that relative to the more sophisticated and costly staggered sampling methods, linear interpolation between sequential measurements is a surprisingly effective method for increasing time resolution. Additional error can be added to a time series constructed in this manner if a suboptimal sequential sampling schedule is chosen. Staggering measurements is one way to avoid this effect. There is little to be gained from deconvolving staggered measurements, except at very low values of random measurement error (< 5 %). Assuming 20 % random measurement error, one can expect average recovery errors of 1.33-2.81 µg m-3 when using 4-8 h-long sequential and staggered samples to measure time series of concentration values ranging from 0.13-29.16 µg m-3. For 4 h samples, 19-47 % of this total error can be attributed to the process of increasing time resolution alone, depending on the method used, meaning that measurement precision would only be improved by 0.30-0.75 µg m-3 if samples could be collected over 1 h instead of 4 h. Devising a

  10. Photoacoustic determination of optical properties of aerosol particles collected on filters: development of a method taking into account substrate reflectivity.

    PubMed

    Röhl, R; McClenny, W A; Palmer, R A

    1982-02-01

    The absorptivity of soot and methylene blue particles collected on Teflon filters is derived from photoacoustic measurements by least squares fitting a simple expression based on Beer's law to the experimental data. Refinements of the expression take into account the diffuse reflection of light by the filter substrate, yielding a base 10 absorptivity at 600 nm for soot of 3.00 +/- 0.37 m(2)/g. This value is in close agreement with the result of transmission measurements performed on the same samples (3.08 +/- 0.05 m(2)/g). PMID:20372465

  11. Measurements of BC-Containing Aerosol and Ice Nucleation Active Residuals in Colorado.

    NASA Astrophysics Data System (ADS)

    Katich, J. M.

    2015-12-01

    A recent ice nucleation (IN) chamber inter-comparison study (FIN-3) provided an opportunity to deploy two single particle soot photometers (SP2s) to the Stormpeak Laboratory in the mountains of Colorado in September of 2015. Aerosol was sampled from ambient air, as well as from behind both a coarse-mode aerosol concentrator and an ice nucleation chamber providing ice residuals. The SP2s characterized the size and mixing state of refractory black carbon-containing particles. Initial analyses of laboratory and ambient data collected over 3 weeks will be presented, with an emphasis on both coarse mode BC observations and BC contributions to ice residuals. The results will help constrain the role of BC from local and regional sources on heterogeneous ice nucleation.

  12. The Development of Electrostatic Precipitation-Electrospray Ionization Mass Spectrometry (EP-ESI-MS) for Atmospheric Aerosol Analysis

    NASA Astrophysics Data System (ADS)

    He, S.; Hogan, C. J., Jr.; Naqwi, A.; Gross, D. S.; Li, L.; Duan, H.; Jiang, L.; Flowers, J.; Grubb, E.; Au, L.

    2015-12-01

    Chemical composition analysis of atmospheric aerosols is of considerable interest and has been facilitated by mass spectrometry. Electrospray ionization (ESI) is a suitable mode of ion generation of many organic species comprising aerosol particles, as it leads to minimal analyte fragmentation. However, particles exist in the atmosphere at mass concentrations of the order 10 μg/m3 or less in many environments and are highly heterogeneous; low concentrations and chemical complexity have limited ESI application in aerosol analysis. In this presentation, the development of an approach to apply ESI to molecules within submicrometer and nanometer scale aerosol particles is discussed. The technique, which we term electrostatic precipitation-ESI-MS (EP-ESI-MS), utilizes unipolar ionization to charge particles, electrostatic precipitation to collect particles on the tip of a tungsten rod, and subsequently, by flowing liquid over the rod, ESI and mass analysis of dissolved species originating from the collected particles. EP-ESI-MS is shown to enable analysis of nanogram quantities of collected inorganic and organic components. Furthermore, it is coupled with a tandem mass spectrometry and challenged with oxidation products of α-pinene to investigate its capability of enabling structure analysis of complex organic compounds in aerosol particles. With EP-ESI-MS, the identification of chemical components in aerosol particles is realized and the integrated mass spectrometric signals are found to be a monotonic function of the analyte mass concentration in the aerosol phase. Additionally, it is shown to have a dynamic range of 5 orders of magnitude in mass, making it suitable for molecular analysis of aerosol particles in laboratory settings, as well as analysis of atmospheric aerosols in ambient air.

  13. Processing of aerosol particles within the Habshan pollution plume

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  14. Mount Saint Helens aerosol evolution

    NASA Technical Reports Server (NTRS)

    Oberbeck, V. R.; Farlow, N. H.; Snetsinger, K. G.; Ferry, G. V.; Fong, W.; Hayes, D. M.

    1982-01-01

    Stratospheric aerosol samples were collected using a wire impactor during the year following the eruption of Mt. St. Helens. Analysis of samples shows that aerosol volume increased for 6 months due to gas-to-particle conversion and then decreased to background levels in the following 6 months.

  15. Airborne Aerosol In situ Measurements during TCAP: A Closure Study of Total Scattering

    SciTech Connect

    Kassianov, Evgueni I.; Berg, Larry K.; Pekour, Mikhail S.; Flynn, Connor J.; Tomlinson, Jason M.; Chand, Duli; Shilling, John E.; Ovchinnikov, Mikhail; Barnard, James C.; Sedlacek, Art; Schmid, Beat

    2015-07-31

    We present here a framework for calculating the total scattering of both non-absorbing and absorbing aerosol at ambient conditions from aircraft data. The synergistically employed aircraft data involve aerosol microphysical, chemical, and optical components and ambient relative humidity measurements. Our framework is developed emphasizing the explicit use of the complementary chemical composition data for estimating the complex refractive index (RI) of particles, and thus obtaining improved ambient size spectra derived from Optical Particle Counter (OPC) measurements. The feasibility of our framework for improved calculations of total aerosol scattering is demonstrated for different ambient conditions with a wide range of relative humidities (from 5 to 80%) using three types of data collected by the U.S. Department of Energy (DOE) G-1 aircraft during the recent Two-Column Aerosol Project (TCAP). Namely, these three types of data employed are: (1) size distributions measured by an Ultra High Sensitivity Aerosol Spectrometer (UHSAS; 0.06-1 µm), a Passive Cavity Aerosol Spectrometer (PCASP; 0.1-3 µm) and a Cloud and Aerosol Spectrometer (CAS; 0.6- >10 µm), (2) chemical composition data measured by an Aerosol Mass Spectrometer (AMS; 0.06-0.6 µm) and a Single Particle Soot Photometer (SP2; 0.06-0.6 µm), and (3) the dry total scattering coefficient measured by a TSI integrating nephelometer at three wavelengths (0.45, 0.55, 0.7 µm) and scattering enhancement factor measured with a humidification system at three RHs (near 45%, 65% and 90%) at a single wavelength (0.525 µm). We demonstrate that good agreement (~10% on average) between the observed and calculated scattering at these three wavelengths can be obtained using the best available chemical composition data for the RI-based correction of the OPC-derived size spectra. We also demonstrate that ignoring the RI-based correction and using non-representative RI values can cause a substantial underestimation (~40

  16. Vertical Profiles of Aerosol Optical Properties Over Central Illinois and Comparison with Surface and Satellite Measurements

    NASA Technical Reports Server (NTRS)

    Sheridan P. J.; Andrews, E.; Ogren, J A.; Tackett, J. L.; Winker, D. M.

    2012-01-01

    Between June 2006 and September 2009, an instrumented light aircraft measured over 400 vertical profiles of aerosol and trace gas properties over eastern and central Illinois. The primary objectives of this program were to (1) measure the in situ aerosol properties and determine their vertical and temporal variability and (2) relate these aircraft measurements to concurrent surface and satellite measurements. Underflights of the CALIPSO satellite show reasonable agreement in a majority of retrieved profiles between aircraft-measured extinction at 532 nm (adjusted to ambient relative humidity) and CALIPSO-retrieved extinction, and suggest that routine aircraft profiling programs can be used to better understand and validate satellite retrieval algorithms. CALIPSO tended to overestimate the aerosol extinction at this location in some boundary layer flight segments when scattered or broken clouds were present, which could be related to problems with CALIPSO cloud screening methods. The in situ aircraft-collected aerosol data suggest extinction thresholds for the likelihood of aerosol layers being detected by the CALIOP lidar. These statistical data offer guidance as to the likelihood of CALIPSO's ability to retrieve aerosol extinction at various locations around the globe.

  17. Indian aerosols: present status.

    PubMed

    Mitra, A P; Sharma, C

    2002-12-01

    This article presents the status of aerosols in India based on the research activities undertaken during last few decades in this region. Programs, like International Geophysical Year (IGY), Monsoon Experiment (MONEX), Indian Middle Atmospheric Program (IMAP) and recently conducted Indian Ocean Experiment (INDOEX), have thrown new lights on the role of aerosols in global change. INDOEX has proved that the effects of aerosols are no longer confined to the local levels but extend at regional as well as global scales due to occurrence of long range transportation of aerosols from source regions along with wind trajectories. The loading of aerosols in the atmosphere is on rising due to energy intensive activities for developmental processes and other anthropogenic activities. One of the significant observation of INDOEX is the presence of high concentrations of carbonaceous aerosols in the near persistent winter time haze layer over tropical Indian Ocean which have probably been emitted from the burning of fossil-fuels and biofuels in the source region. These have significant bearing on the radiative forcing in the region and, therefore, have potential to alter monsoon and hydrological cycles. In general, the SPM concentrations have been found to be on higher sides in ambient atmosphere in many Indian cities but the NOx concentrations have been found to be on lower side. Even in the haze layer over Indian Ocean and surrounding areas, the NOx concentrations have been reported to be low which is not conducive of O3 formation in the haze/smog layer. The acid rain problem does not seem to exist at the moment in India because of the presence of neutralizing soil dust in the atmosphere. But the high particulate concentrations in most of the cities' atmosphere in India are of concern as it can cause deteriorated health conditions. PMID:12492171

  18. Indian aerosols: present status.

    PubMed

    Mitra, A P; Sharma, C

    2002-12-01

    This article presents the status of aerosols in India based on the research activities undertaken during last few decades in this region. Programs, like International Geophysical Year (IGY), Monsoon Experiment (MONEX), Indian Middle Atmospheric Program (IMAP) and recently conducted Indian Ocean Experiment (INDOEX), have thrown new lights on the role of aerosols in global change. INDOEX has proved that the effects of aerosols are no longer confined to the local levels but extend at regional as well as global scales due to occurrence of long range transportation of aerosols from source regions along with wind trajectories. The loading of aerosols in the atmosphere is on rising due to energy intensive activities for developmental processes and other anthropogenic activities. One of the significant observation of INDOEX is the presence of high concentrations of carbonaceous aerosols in the near persistent winter time haze layer over tropical Indian Ocean which have probably been emitted from the burning of fossil-fuels and biofuels in the source region. These have significant bearing on the radiative forcing in the region and, therefore, have potential to alter monsoon and hydrological cycles. In general, the SPM concentrations have been found to be on higher sides in ambient atmosphere in many Indian cities but the NOx concentrations have been found to be on lower side. Even in the haze layer over Indian Ocean and surrounding areas, the NOx concentrations have been reported to be low which is not conducive of O3 formation in the haze/smog layer. The acid rain problem does not seem to exist at the moment in India because of the presence of neutralizing soil dust in the atmosphere. But the high particulate concentrations in most of the cities' atmosphere in India are of concern as it can cause deteriorated health conditions.

  19. Isoprene Epoxydiols as Precursors to Secondary Organic Aerosol Formation: Acid-Catalyzed Reactive Uptake Studies with Authentic Compounds

    PubMed Central

    Lin, Ying-Hsuan; Zhang, Zhenfa; Docherty, Kenneth S.; Zhang, Haofei; Budisulistiorini, Sri Hapsari; Rubitschun, Caitlin L.; Shaw, Stephanie L.; Knipping, Eladio M.; Edgerton, Eric S.; Kleindienst, Tadeusz E.; Gold, Avram; Surratt, Jason D.

    2011-01-01

    Isoprene epoxydiols (IEPOX), formed from the photooxidation of isoprene under low-NOx conditions, have recently been proposed as precursors of secondary organic aerosol (SOA) on the basis of mass spectrometric evidence. In the present study, IEPOX isomers were synthesized in high purity (> 99%) to investigate their potential to form SOA via reactive uptake in a series of controlled dark chamber studies followed by reaction product analyses. IEPOX-derived SOA was substantially observed only in the presence of acidic aerosols, with conservative lower-bound yields of 4.7–6.4% for β-IEPOX and 3.4–5.5% for δ-IEPOX, providing direct evidence for IEPOX isomers as precursors to isoprene SOA. These chamber studies demonstrate that IEPOX uptake explains the formation of known isoprene SOA tracers found in ambient aerosols, including 2-methyltetrols, C5-alkene triols, dimers, and IEPOX-derived organosulfates. Additionally, we show reactive uptake on the acidified sulfate aerosols supports a previously unreported acid-catalyzed intramolecular rearrangement of IEPOX to cis- and trans-3-methyltetrahydrofuran-3,4-diols (3-MeTHF-3,4-diols) in the particle phase. Analysis of these novel tracer compounds by aerosol mass spectrometry (AMS) suggests that they contribute to a unique factor resolved from positive matrix factorization (PMF) of AMS organic aerosol spectra collected from low-NOx, isoprene-dominated regions influenced by the presence of acidic aerosols. PMID:22103348

  20. Carbonaceous aerosols from prescribed burning of a boreal forest ecosystem

    SciTech Connect

    Mazurek, M.A. ); Cofer, W.R. III; Levine, J.S. . Langley Research Center)

    1990-10-01

    The identity and ambient mass concentrations of radiatively important carbonaceous aerosols were measured for a boreal forest prescribed burn conducted in northern Ontario, CAN in August 1989. Nonsize-segregated airborne particles were collected for smoldering-fire and full-fire conditions using a helicopter sampling platform. Total carbon (TC), organic carbon (OC) and elemental carbon (EC) were measured. Smoke plume mass concentrations of the OC and EC particles were greatest for full-fire conditions and had ranges of 1.560 to 2.160 mg/m{sup {minus}1} (OC) and 0.120 to 0.160 mg/m{sup {minus}3} (EC) with OC:EC ratios of 10 to 18, respectively. Smoldering fire conditions showed smoke plume OC and EC levels of 0.570--1.030 mg/m{sup {minus}3} (OC) and 0.006--0.050 mg/m{sup {minus}3} (EC) and much higher ratios of OC:EC (21 to 95). These aerosol data indicate the formation of EC particles is greatest during full-fire combustion of boreal forest material relative to smoldering combustion. However, EC particles comprise a minor fraction of the particulate carbon smoke aerosols for both full-fire and smoldering conditions; the major component of carbonaceous smoke aerosols emitted during the prescribed burn is OC. Overall, the OC and EC in-plume smoke aerosol data show nonuniform production of these particles during various stages of the prescribed burn, and major differences in the type of carbonaceous aerosol that is generated (OC versus EC).

  1. Relating Aerosol Mass and Optical Depth in the Summertime Continental Boundary Layer

    NASA Astrophysics Data System (ADS)

    Brock, C. A.; Wagner, N.; Middlebrook, A. M.; Attwood, A. R.; Washenfelder, R. A.; Brown, S. S.; McComiskey, A. C.; Gordon, T. D.; Welti, A.; Carlton, A. G.; Murphy, D. M.

    2014-12-01

    Aerosol optical depth (AOD), the column-integrated ambient aerosol light extinction, is determined from satellite and ground-based remote sensing measurements. AOD is the parameter most often used to validate earth system model simulations of aerosol mass. Relating aerosol mass to AOD, however, is problematic due to issues including aerosol water uptake as a function of relative humidity (RH) and the complicated relationship between aerosol physicochemical properties and light extinction. Measurements of aerosol microphysical, chemical, and optical properties help to constrain the relationship between aerosol mass and optical depth because aerosol extinction at ambient RH is a function of the abundance, composition and size distribution of the aerosol. We use vertical profiles of humidity and dry aerosol extinction observed in the southeastern United States (U.S.) to examine the relationship between submicron aerosol mass concentration and extinction at ambient RH. We show that the κ-Köhler parameterization directly, and without additional Mie calculations, describes the change in extinction with varying RH as a function of composition for both aged aerosols typical of the polluted summertime continental boundary layer and the biomass burning aerosols we encountered. We calculate how AOD and the direct radiative effect in the eastern U.S. have likely changed due to trends in aerosol composition in recent decades. We also examine the sensitivity of AOD to the RH profile and to aerosol composition, size distribution and abundance.

  2. Quantification and radiocarbon source apportionment of black carbon in atmospheric aerosols using the CTO-375 method

    NASA Astrophysics Data System (ADS)

    Zencak, Zdenek; Elmquist, Marie; Gustafsson, Örjan

    To make progress towards linking the atmosphere and biogeosphere parts of the black carbon (BC) cycle, a chemothermal oxidation method (CTO-375), commonly applied for isolating BC from complex geomatrices such as soils, sediments and aquatic particles, was applied to investigate the BC also in atmospheric particles. Concentrations and 14C-based source apportionment of CTO-375 based BC was established for a reference aerosol (NIST RM-8785) and for wintertime aerosols collected in Stockholm and in a Swedish background area. The results were compared with thermal-optical (OC/EC) measurements. For NIST RM-8785, a good agreement was found between the BC CTO-375 concentration and the reported elemental carbon (EC) concentration measured by the "Speciation Trends Network—National Institute of Occupational Safety and Health" method (EC NIOSH) with BC CTO-375 of 0.054±0.002 g g -1 and EC NIOSH of 0.067±0.008 g g -1. In contrast, there was an average factor of ca. 20 difference between BC CTO-375 and EC NIOSH for the ambient Scandinavian wintertime aerosols, presumably reflecting a combination of BC CTO-375 isolating only the recalcitrant soot-BC portion of the BC continuum and the EC NIOSH metric inadvertently including some intrinsically non-pyrogenic organic matter. Isolation of BC CTO-375 with subsequent off-line radiocarbon analysis yielded fraction modern values (fM) for total organic carbon (TOC) of 0.93 (aerosols from a Swedish background area), and 0.58 (aerosols collected in Stockholm); whereas the fM for BC CTO-375 isolates were 1.08 (aerosols from a Swedish background area), and 0.87 (aerosols collected in Stockholm). This radiocarbon-based source apportionment suggests that contribution from biomass combustion to cold-season atmospheric BC CTO-375 in Stockholm was 70% and in the background area 88%.

  3. Exposures to acidic aerosols.

    PubMed

    Spengler, J D; Keeler, G J; Koutrakis, P; Ryan, P B; Raizenne, M; Franklin, C A

    1989-02-01

    Ambient monitoring of acid aerosols in four U.S. cities and in a rural region of southern Ontario clearly show distinct periods of strong acidity. Measurements made in Kingston, TN, and Steubenville, OH, resulted in 24-hr H+ ion concentrations exceeding 100 nmole/m3 more than 10 times during summer months. Periods of elevated acidic aerosols occur less frequently in winter months. The H+ determined during episodic conditions in southern Ontario indicates that respiratory tract deposition can exceed the effects level reported in clinical studies. Observed 12-hr H+ concentrations exceeded 550 nmole/m3 (approximately 27 micrograms/m3 H2SO4). The maximum estimated 1-hr concentration exceeded 1500 nmole/m3 for H+ ions. At these concentrations, an active child might receive more than 2000 nmole of H+ ion in 12 hr and in excess of 900 nmole during the hour when H2SO4 exceeded 50 micrograms/m3.

  4. Supercritical Fluid Extraction and Analysis of Tropospheric Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Hansen, Kristen J.

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

  5. Aerosol Lidar and MODIS Satellite Comparisons for Future Aerosol Loading Forecast

    NASA Technical Reports Server (NTRS)

    DeYoung, Russell; Szykman, James; Severance, Kurt; Chu, D. Allen; Rosen, Rebecca; Al-Saadi, Jassim

    2006-01-01

    Knowledge of the concentration and distribution of atmospheric aerosols using both airborne lidar and satellite instruments is a field of active research. An aircraft based aerosol lidar has been used to study the distribution of atmospheric aerosols in the California Central Valley and eastern US coast. Concurrently, satellite aerosol retrievals, from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument aboard the Terra and Aqua satellites, were take over the Central Valley. The MODIS Level 2 aerosol data product provides retrieved ambient aerosol optical properties (e.g., optical depth (AOD) and size distribution) globally over ocean and land at a spatial resolution of 10 km. The Central Valley topography was overlaid with MODIS AOD (5x5 sq km resolution) and the aerosol scattering vertical profiles from a lidar flight. Backward air parcel trajectories for the lidar data show that air from the Pacific and northern part of the Central Valley converge confining the aerosols to the lower valley region and below the mixed layer. Below an altitude of 1 km, the lidar aerosol and MODIS AOD exhibit good agreement. Both data sets indicate a high presence of aerosols near Bakersfield and the Tehachapi Mountains. These and other results to be presented indicate that the majority of the aerosols are below the mixed layer such that the MODIS AOD should correspond well with surface measurements. Lidar measurements will help interpret satellite AOD retrievals so that one day they can be used on a routine basis for prediction of boundary layer aerosol pollution events.

  6. Airborne aerosol in situ measurements during TCAP: A closure study of total scattering

    DOE PAGESBeta

    Kassianov, Evgueni; Sedlacek, Arthur; Berg, Larry K.; Pekour, Mikhail; Barnard, James; Chand, Duli; Flynn, Connor; Ovchinnikov, Mikhail; Schmid, Beat; Shilling, John; et al

    2015-07-31

    We present a framework for calculating the total scattering of both non-absorbing and absorbing aerosol at ambient conditions from aircraft data. Our framework is developed emphasizing the explicit use of chemical composition data for estimating the complex refractive index (RI) of particles, and thus obtaining improved ambient size spectra derived from Optical Particle Counter (OPC) measurements. The feasibility of our framework for improved calculations of total scattering is demonstrated using three types of data collected by the U.S. Department of Energy’s (DOE) aircraft during the Two-Column Aerosol Project (TCAP). Namely, these data types are: (1) size distributions measured by amore » suite of OPC’s; (2) chemical composition data measured by an Aerosol Mass Spectrometer and a Single Particle Soot Photometer; and (3) the dry total scattering coefficient measured by a integrating nephelometer and scattering enhancement factor measured with a humidification system. We demonstrate that good agreement (~10%) between the observed and calculated scattering can be obtained under ambient conditions (RH < 80%) by applying chemical composition data for the RI-based correction of the OPC-derived size spectra. We also demonstrate that ignoring the RI-based correction or using non-representative RI values can cause a substantial underestimation (~40%) or overestimation (~35%) of the calculated scattering, respectively.« less

  7. Airborne aerosol in situ measurements during TCAP: A closure study of total scattering

    SciTech Connect

    Kassianov, Evgueni; Sedlacek, Arthur; Berg, Larry K.; Pekour, Mikhail; Barnard, James; Chand, Duli; Flynn, Connor; Ovchinnikov, Mikhail; Schmid, Beat; Shilling, John; Tomlinson, Jason; Fast, Jerome

    2015-07-31

    We present a framework for calculating the total scattering of both non-absorbing and absorbing aerosol at ambient conditions from aircraft data. Our framework is developed emphasizing the explicit use of chemical composition data for estimating the complex refractive index (RI) of particles, and thus obtaining improved ambient size spectra derived from Optical Particle Counter (OPC) measurements. The feasibility of our framework for improved calculations of total scattering is demonstrated using three types of data collected by the U.S. Department of Energy’s (DOE) aircraft during the Two-Column Aerosol Project (TCAP). Namely, these data types are: (1) size distributions measured by a suite of OPC’s; (2) chemical composition data measured by an Aerosol Mass Spectrometer and a Single Particle Soot Photometer; and (3) the dry total scattering coefficient measured by a integrating nephelometer and scattering enhancement factor measured with a humidification system. We demonstrate that good agreement (~10%) between the observed and calculated scattering can be obtained under ambient conditions (RH < 80%) by applying chemical composition data for the RI-based correction of the OPC-derived size spectra. We also demonstrate that ignoring the RI-based correction or using non-representative RI values can cause a substantial underestimation (~40%) or overestimation (~35%) of the calculated scattering, respectively.

  8. Behavioral-physiological effects of red phosphorous smoke inhalation on two wildlife species. Task 1. Inhalation equipment development/ambient CO evaluation/aerosol distribution and air-quality study. Final report, March 1985-December 1986

    SciTech Connect

    Sterner, R.T.; Shumake, S.A.; Johns, B.E.; Thompson, R.D.

    1987-12-01

    Tests to evaluate the spatial and temporal uniformity of red phosphorous - butyl rubber smoke produced in a commercial 1-CuM inhalation chamber are described. Several modifications to the inhalation exposure system aimed at improving air filtration, relative humidity, and temperature control for the conduct of animal studies are also presented. Smoke generation involved the use of a system for the continuous generation of phosphoric acid aerosols. Assessments of spatial and temporal uniformity of smoke were based upon measurements of aerosol mass concentration (gravimetric analysis), phosphoric acid deposition (titration analysis), aerosol opacity (infrared sensor), and particle size (cascade impactor); assessments of air quality and combustion products within the chamber involved checks for oxygen, carbon dioxide, phosphine, hexane, and carbon monoxide using either gas chromatography or industrial-hygiene-analyzer tubes. Results for aerosol mass, phosphoric acid, and particle size showed that the within-chamber smoke was highly uniform among burns. Although a number of statistically significant effects were obtained, further inspection showed these to be limited to specific sampling locations and within a priori criteria established to define acceptable uniformity.

  9. Measurements of Natural Radioactivity in Submicron Aerosols in Mexico City.

    NASA Astrophysics Data System (ADS)

    Gaffney, J. S.; Marley, N. A.; Sterling, K.; Sturchio, N. C.

    2003-12-01

    Natural radionuclides can be useful in evaluating the transport of ozone and aerosols in the troposphere. Beryllium-7, which is produced by cosmic ray interactions in the upper troposphere and lower stratosphere and becomes adsorbed on fine aerosols, can be a useful indicator of upper air transport into a region. Lead-210 is produced by the decay of radon-222 out-gassed into the lower atmosphere from ground-based uranium deposits. Potassium-40, found in soils, can act as a measure of wind-blown dust and also comes from burning of wood and other biomass that is enriched in this natural radioisotope. Thus, both lead-210 and potassium-40 can aid in identification of aerosols sourced in the lower atmosphere. As part of our continuing interest in the lifetimes and sources of aerosols and their radiative effects, we report here measurements of fine aerosol radioactivity in Mexico City, one of the largest megacities in the world. Samples were collected on quartz fiber filters by using cascade impactors (Sierra type, Anderson Instruments) and high-volume air samplers from the rooftop of the main laboratory of El Centro Nacional de Investigacion y Capacitacion Ambiental (CENICA). By using stage 4 of the impactor and timers, we were able to collect integrated samples of sizes > 1 micrometer and < 1 micrometer over 12-hr time periods daily for approximately one month in April 2003. Samples were counted at the University of Illinois at Chicago by using state-of-the-art gamma counting (beryllium-7, 477.6 keV; potassium-40, 1460.8 keV; lead-210, 46.5 keV). The beryllium-7 data indicate one possible upper-air transport event during April 2003. As expected, the lead-210 data indicate very little soil contribution to the fine aerosol. The potassium-40 data showed an increase in fine aerosol potassium during Holy Week that might be attributed to local combustion of biomass fuels. The data will be presented and discussed in light of future data analysis and comparison with other

  10. Characterization and source apportionment of aerosol light extinction in Chengdu, southwest China

    NASA Astrophysics Data System (ADS)

    Tao, Jun; Zhang, Leiming; Cao, Junji; Hsu, Shih-Chieh; Xia, Xiangao; Zhang, Zhisheng; Lin, Zejian; Cheng, Tiantao; Zhang, Renjian

    2014-10-01

    To investigate aerosol properties in the Sichuan Basin of China, field aerosol sampling was carried out in Chengdu, China during four one-month periods, each in a different season in 2011. Aerosol scattering coefficient (bsp) at dry (RH<40%) and wet (40% < RH<90%) conditions and aerosol absorption coefficient (bap) were measured. Additionally, daily PM2.5 and PM10 samples were also collected. PM2.5 samples were subject to chemical analysis for various chemical components including major water-soluble ions, organic and elemental carbon (OC and EC), trace elements, as well as anhydrosugar Levoglucosan (LG) and Mannosan (MN). A multiple linear regression analysis was applied to the measured dry bsp against (NH4)2SO4, NH4NO3, organic mass (OM), fine soil (FS), and coarse mass (CM, PM2.5-10), and to the measured bap against EC in all the four seasons to evaluate the impact of individual chemical components of PM2.5 and CM on aerosol light extinction (bext = bsp + bap). Mass scattering efficiency (MSE) and mass absorption efficiency (MAE) of the individual chemical components of PM2.5 were estimated based on seasonal regression equations and were then used for estimating bext. The annual bsp, bap and single scattering albedo (SSA) at dry conditions were 456 ± 237 Mm-1, 96 ± 48 Mm-1 and 0.82 ± 0.05, respectively. The annual average bsp at ambient conditions estimated through hygroscopic curve of aerosol (f(RH)) was 763 ± 415 Mm-1, which was 1.7 times of the dry bsp. The annual average SSA at ambient conditions also increased to 0.88 ± 0.04. The estimated dry bext was only 2 ± 9% higher than the measurements and the estimated ambient bext from individual chemical components was only 1 ± 10% lower, on an annual basis, than that estimated from using f(RH). Secondary inorganic aerosols, coal combustion, biomass burning, iron and steel industry, Mo-related industry, soil dust, and CM to bext were estimated to account for 41 ± 19%, 18 ± 12%, 14 ± 13%, 13 ± 11%, 5

  11. Daily and hourly chemical impact of springtime transboundary aerosols on Japanese air quality

    NASA Astrophysics Data System (ADS)

    Moreno, T.; Kojima, T.; Amato, F.; Lucarelli, F.; de la Rosa, J.; Calzolai, G.; Nava, S.; Chiari, M.; Alastuey, A.; Querol, X.; Gibbons, W.

    2013-02-01

    The regular eastward drift of transboundary aerosol intrusions from the Asian mainland into the NW Pacific region has a pervasive impact on air quality in Japan, especially during springtime. Analysis of 24-h filter samples with Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) and Mass Spectrometry (ICP-MS), and hourly Streaker with Particle Induced X-ray Emission (PIXE) samples collected continuously for six weeks reveal the chemistry of successive waves of natural mineral desert dust ("Kosa") and metalliferous sulphatic pollutants arriving in western Japan during spring 2011. The main aerosol sources recognised by Positive Matrix Factorization (PMF) analysis of Streaker data are mineral dust and fresh sea salt (both mostly in the coarser fraction PM2.5-10), As-bearing sulphatic aerosol (PM0.1-2.5), metalliferous sodic particulate matter (PM) interpreted as aged, industrially contaminated marine aerosol, and ZnCu-bearing aerosols. Whereas mineral dust arrivals are typically highly transient, peaking over a few hours, sulphatic intrusions build up and decline more slowly, and are accompanied by notable rises in ambient concentrations of metallic trace elements such as Pb, As, Zn, Sn and Cd. The magnitude of the loss in regional air quality due to the spread and persistence of pollution from mainland Asia is especially clear when cleansing oceanic air advects westward across Japan, removing the continental influence and reducing concentrations of the undesirable metalliferous pollutants by over 90%. Our new chemical database, especially the Streaker data, demonstrates the rapidly changing complexity of ambient air inhaled during these transboundary events, and implicates Chinese coal combustion as the main source of the anthropogenic aerosol component.

  12. Daily and hourly chemical impact of springtime transboundary aerosols on Japanese air quality

    NASA Astrophysics Data System (ADS)

    Moreno, T.; Kojima, T.; Amato, F.; Lucarelli, F.; Nava, S.; de la Rosa, J.; Calzolai, G.; Chiari, M.; Alastuey, A.; Querol, X.; Gibbons, W.

    2012-09-01

    The regular eastward drift of transboundary aerosol intrusions from the Asian mainland into the NW Pacific region has a~pervasive impact on air quality in Japan, especially during springtime. Analysis of 24-h filter samples (ICP-AES and ICP-MS) and hourly Streaker (PIXE) samples of particulate matter collected continuously for six weeks reveal the chemistry of successive waves of natural mineral desert dust ("Kosa") and metalliferous sulphatic pollutants arriving in Western Japan during spring 2011. The main aerosol sources recognised by PMF analysis of Streaker data are mineral dust and fresh sea salt (both mostly in the coarser fraction PM2.5-10), As-bearing sulphatic aerosol (PM0.1-2.5), metalliferous sodic PM interpreted as aged, industrially contaminated marine aerosol, and ZnCu-bearing aerosols. Whereas mineral dust arrivals are typically highly transient, peaking over a few hours, sulphatic intrusions build up and decline more slowly, and are accompanied by notable rises in ambient concentrations of metallic trace elements such as Pb, As, Zn, Sn and Cd. The magnitude of the loss in regional air quality due to the spread and persistence of pollution from mainland Asia is especially clear when cleansing oceanic air advects westward across Japan, removing the continental influence and reducing concentrations of the more undesirable metalliferous pollutants by over 90%. Our new chemical database, especially the Streaker data, demonstrates the rapidly changing complexity of ambient air inhaled during these transboundary events, and implicates Chinese coal combustion as the main source of the anthropogenic aerosol component.

  13. Near real time vapor detection and enhancement using aerosol adsorption

    DOEpatents

    Novick, Vincent J.; Johnson, Stanley A.

    1999-01-01

    A vapor sample detection method where the vapor sample contains vapor and ambient air and surrounding natural background particles. The vapor sample detection method includes the steps of generating a supply of aerosol that have a particular effective median particle size, mixing the aerosol with the vapor sample forming aerosol and adsorbed vapor suspended in an air stream, impacting the suspended aerosol and adsorbed vapor upon a reflecting element, alternatively directing infrared light to the impacted aerosol and adsorbed vapor, detecting and analyzing the alternatively directed infrared light in essentially real time using a spectrometer and a microcomputer and identifying the vapor sample.

  14. Near real time vapor detection and enhancement using aerosol adsorption

    DOEpatents

    Novick, V.J.; Johnson, S.A.

    1999-08-03

    A vapor sample detection method is described where the vapor sample contains vapor and ambient air and surrounding natural background particles. The vapor sample detection method includes the steps of generating a supply of aerosol that have a particular effective median particle size, mixing the aerosol with the vapor sample forming aerosol and adsorbed vapor suspended in an air stream, impacting the suspended aerosol and adsorbed vapor upon a reflecting element, alternatively directing infrared light to the impacted aerosol and adsorbed vapor, detecting and analyzing the alternatively directed infrared light in essentially real time using a spectrometer and a microcomputer and identifying the vapor sample. 13 figs.

  15. Apportionment of urban aerosol sources in Cork (Ireland) by synergistic measurement techniques.

    PubMed

    Dall'Osto, Manuel; Hellebust, Stig; Healy, Robert M; O'Connor, Ian P; Kourtchev, Ivan; Sodeau, John R; Ovadnevaite, Jurgita; Ceburnis, Darius; O'Dowd, Colin D; Wenger, John C

    2014-09-15

    The sources of ambient fine particulate matter (PM2.5) during wintertime at a background urban location in Cork city (Ireland) have been determined. Aerosol chemical analyses were performed by multiple techniques including on-line high resolution aerosol time-of-flight mass spectrometry (Aerodyne HR-ToF-AMS), on-line single particle aerosol time-of-flight mass spectrometry (TSI ATOFMS), on-line elemental carbon-organic carbon analysis (Sunset_EC-OC), and off-line gas chromatography/mass spectrometry and ion chromatography analysis of filter samples collected at 6-h resolution. Positive matrix factorization (PMF) has been carried out to better elucidate aerosol sources not clearly identified when analyzing results from individual aerosol techniques on their own. Two datasets have been considered: on-line measurements averaged over 2-h periods, and both on-line and off-line measurements averaged over 6-h periods. Five aerosol sources were identified by PMF in both datasets, with excellent agreement between the two solutions: (1) regional domestic solid fuel burning--"DSF_Regional," 24-27%; (2) local urban domestic solid fuel burning--"DSF_Urban," 22-23%; (3) road vehicle emissions--"Traffic," 15-20%; (4) secondary aerosols from regional anthropogenic sources--"SA_Regional" 9-13%; and (5) secondary aged/processed aerosols related to urban anthropogenic sources--"SA_Urban," 21-26%. The results indicate that, despite regulations for restricting the use of smoky fuels, solid fuel burning is the major source (46-50%) of PM2.5 in wintertime in Cork, and also likely other areas of Ireland. Whilst wood combustion is strongly associated with OC and EC, it was found that peat and coal combustion is linked mainly with OC and the aerosol from these latter sources appears to be more volatile than that produced by wood combustion. Ship emissions from the nearby port were found to be mixed with the SA_Regional factor. The PMF analysis allowed us to link the AMS cooking organic

  16. Laboratory and field measurements of organic aerosols with the photoionization aerosol mass spectrometer

    NASA Astrophysics Data System (ADS)

    Dreyfus, Matthew A.

    Analytical methods developed to sample and characterize ambient organic aerosols often face the trade-off between long sampling times and the loss of detailed information regarding specific chemical species present. The soft, universal ionization scheme of the Photoionization Aerosol Mass Spectrometer (PIAMS) allows for identification of various chemical compounds by a signature ion, often the molecular ion. The goal of this thesis work is to apply PIAMS to both laboratory and field experiments to answer questions regarding the formation, composition, and behavior of organic aerosols. To achieve this goal, a variety of hardware and software upgrades were administered to PIAMS to optimize the instrument. Data collection and processing software were either refined or built from the ground up to simplify difficult or monotonous tasks. Additional components were added to PIAMS with the intent to automate the instrument, enhance the results, and make the instrument more rugged and user-friendly. These changes, combined with the application of an external particle concentration system (mini-Versatile Aerosol Concentration Enrichment System, m-VACES), allowed PIAMS to be suitable for field measurements of organic aerosols. Two such field campaigns were completed, both at the State of Delaware Air Quality Monitoring Site in Wilmington, Delaware: a one week period in June, 2006, and an 18 day period in October and November of 2007. A sampling method developed was capable of collecting sufficient ambient organic aerosol and analyzing it with a time resolution of 3.5 minutes. Because of this method, short term concentration changes of individual species can be tracked. Combined with meteorological data, the behavior of these species can be analyzed as a function of time or wind direction. Many compounds are found at enhanced levels during the evening/night-time hours; potentially due to the combined effects of temperature inversion, and fresh emissions in a cooler environment

  17. Physicochemical and Toxicological Characteristics of Semi-volatile Components of Atmospheric Aerosols in an Urban Environment

    NASA Astrophysics Data System (ADS)

    Verma, V.; Pakbin, P.; Cheung, K. L.; Cho, A. K.; Schauer, J. J.; Shafer, M. M.; Kleinman, M. T.; Sioutas, C.

    2010-12-01

    Recent toxicological studies have confirmed the oxidative properties of atmospheric aerosols and their capability to generate reactive oxygen species (ROS) in biological systems (Chen and Lippmann, 2009). While the links between aerosol toxicity and refractory transition metals present in ambient particulate matter (PM) have been documented, there are limited studies investigating the oxidative characteristics of semi-volatile species. The goal of present study is to examine the contribution of semi-volatile compounds in the oxidative potential of atmospheric aerosols. Concentrated ambient and thermodenuded quasi-ultrafine particles (<180 nm) were collected using the versatile aerosol concentration enrichment system (VACES) at an urban site near downtown Los Angeles. A thermodenuder (TD) was used to selectively remove the semi-volatile components of these aerosols over the temperature range of 50-200 oC. The oxidative potential of PM was measured by means of the DTT (dithiothreitol) assay. Detailed chemical analyses of PM samples, including organic and elemental carbon, water soluble elements, inorganic ions and polycyclic aromatic hydrocarbons (PAHs), were conducted to quantify the volatility profiles of different PM species, and also to investigate their effect on the measured oxidative potential. Refractory constituents, such as metals and elemental carbon, were marginally affected by heating, while labile species such as organic carbon and PAHs showed progressive loss in concentration with increase in TD temperature. The DTT-measured oxidative potential of PM was significantly decreased as the aerosols were heated and their semi-volatile components were progressively removed (42 %, 47 % and 66 % decrease in DTT activity at 50, 100 and 200 oC, respectively). Regression analysis performed between chemical constituents and DTT activity showed that the oxidative potential was strongly correlated with organic carbon and PAHs (R≥0.80; p≤0.05). Thus, semi

  18. 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.

  19. 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.

  20. Aerosol optical absorption measurements with photoacoustic spectroscopy

    NASA Astrophysics Data System (ADS)

    Liu, Kun; Wang, Lei; Liu, Qiang; Wang, Guishi; Tan, Tu; Zhang, Weijun; Chen, Weidong; Gao, Xiaoming

    2015-04-01

    Many parameters related to radiative forcing in climate research are known only with large uncertainties. And one of the largest uncertainties in global radiative forcing is the contribution from aerosols. Aerosols can scatter or absorb the electromagnetic radiation, thus may have negative or positive effects on the radiative forcing of the atmosphere, respectively [1]. And the magnitude of the effect is directly related to the quantity of light absorbed by aerosols [2,3]. Thus, sensitivity and precision measurement of aerosol optical absorption is crucial for climate research. Photoacoustic spectroscopy (PAS) is commonly recognized as one of the best candidates to measure the light absorption of aerosols [4]. A PAS based sensor for aerosol optical absorption measurement was developed. A 532 nm semiconductor laser with an effective power of 160 mW was used as a light source of the PAS sensor. The PAS sensor was calibrated by using known concentration NO2. The minimum detectable optical absorption coefficient (OAC) of aerosol was determined to be 1 Mm-1. 24 hours continues measurement of OAC of aerosol in the ambient air was carried out. And a novel three wavelength PAS aerosol OAC sensor is in development for analysis of aerosol wavelength-dependent absorption Angstrom coefficient. Reference [1] U. Lohmann and J. Feichter, Global indirect aerosol effects: a review, Atmos. Chem. Phys. 5, 715-737 (2005) [2] M. Z. Jacobson, Strong radiative heating due to the mixing state of black carbon in atmospheric aerosols, Nature 409, 695-697 (2001) [3] V. Ramanathan and G. Carmichae, Global and regional climate changes due to black carbon, nature geoscience 1, 221-227 (2008) [4] W.P Arnott, H. Moosmuller, C. F. Rogers, T. Jin, and R. Bruch, Photoacoustic spectrometer for measuring light absorption by aerosol: instrument description. Atmos. Environ. 33, 2845-2852 (1999).

  1. Comparison Between Lidar and Nephelometer Measurements of Aerosol Hygroscopicity at the Southern Great Plains Atmospheric Radiation Measurement Site

    NASA Technical Reports Server (NTRS)

    Pahlow, M.; Feingold, G.; Jefferson, A.; Andrews, E.; Ogren, J. A.; Wang, J.; Lee, Y.-N.; Ferrare, R. A.

    2004-01-01

    Aerosol hygroscopicity has a significant effect on radiative properties of aerosols. Here a lidar method, applicable to cloud-capped, well-mixed atmospheric boundary layers, is employed to determine the hygroscopic growth factor f(RH) under unperturbed, ambient atmospheric conditions. The data used for the analysis were collected under a wide range of atmospheric aerosol levels during both routine measurement periods and during the intensive operations period (IOP) in May 2003 at the Southern Great Plains (SGP) Climate Research Facility in Oklahoma, USA, as part of the Atmospheric Radiation Measurement (ARM) program. There is a good correlation (approx. 0.7) between a lidar-derived growth factor (measured over the range 85% RH to 96% RH) with a nephelometer-derived growth factor measured over the RH range 40% to 85%. For these RH ranges, the slope of the lidar-derived growth factor is much steeper than that of the nephelometer-derived growth factor, reflecting the rapid increase in particle size with increasing RH. The results are corroborated by aerosol model calculations of lidar and nephelometer equivalent f(RH) based on in situ aerosol size and composition measurements during the IOP. It is suggested that the lidar method can provide useful measurements of the dependence of aerosol optical properties on relative humidity, and under conditions closer to saturation than can currently be achieved with humidified nephelometers.

  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. Aerosolized Antibiotics.

    PubMed

    Restrepo, Marcos I; Keyt, Holly; Reyes, Luis F

    2015-06-01

    Administration of medications via aerosolization is potentially an ideal strategy to treat airway diseases. This delivery method ensures high concentrations of the medication in the targeted tissues, the airways, with generally lower systemic absorption and systemic adverse effects. Aerosolized antibiotics have been tested as treatment for bacterial infections in patients with cystic fibrosis (CF), non-CF bronchiectasis (NCFB), and ventilator-associated pneumonia (VAP). The most successful application of this to date is treatment of infections in patients with CF. It has been hypothesized that similar success would be seen in NCFB and in difficult-to-treat hospital-acquired infections such as VAP. This review summarizes the available evidence supporting the use of aerosolized antibiotics and addresses the specific considerations that clinicians should recognize when prescribing an aerosolized antibiotic for patients with CF, NCFB, and VAP.

  4. Global Aerosols

    Atmospheric Science Data Center

    2013-04-19

    ... sizes and from multiple sources, including biomass burning, mineral dust, sea salt and regional industrial pollution. A color scale is ... desert source region. Deserts are the main sources of mineral dust, and MISR obtains aerosol optical depth at visible wavelengths ...

  5. Organic functional groups in aerosol particles from burning and non-burning forest emissions at a high-elevation mountain site

    NASA Astrophysics Data System (ADS)

    Takahama, S.; Schwartz, R. E.; Russell, L. M.; MacDonald, A. M.; Sharma, S.; Leaitch, W. R.

    2011-07-01

    Ambient particles collected on teflon filters at the Peak of Whistler Mountain, British Columbia (2182 m a.s.l.) during spring and summer 2009 were measured by Fourier transform infrared (FTIR) spectroscopy for organic functional groups (OFG). The project mean and standard deviation of organic aerosol mass concentrations (OM) for all samples was 3.2±3.3 (μg m-3). Measurements of aerosol mass fragments, size, and number concentrations were used to separate fossil-fuel combustion and burning and non-burning forest sources of the measured organic aerosol. The OM was composed of the same anthropogenic and non-burning forest components observed at Whistler mid-valley in the spring of 2008; during the 2009 campaign, biomass burning aerosol was additionally observed from fire episodes occurring between June and September. On average, organic hydroxyl, alkane, carboxylic acid, ketone, and primary amine groups represented 31 %±11 %, 34 %±9 %, 23 %±6 %, 6 %±7 %, and 6 %±3 % of OM, respectively. Ketones in aerosols were associated with burning and non-burning forest origins, and represented up to 27 % of the OM. The organic aerosol fraction resided almost entirely in the submicron fraction without significant diurnal variations. OM/OC mass ratios ranged mostly between 2.0 and 2.2 and O/C atomic ratios between 0.57 and 0.76, indicating that the organic aerosol reaching the site was highly aged and possibly formed through secondary formation processes.

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  7. Mesospheric aerosol sampling spectrometer

    NASA Astrophysics Data System (ADS)

    Knappmiller, Scott; Robertson, Scott; Sternovsky, Zoltan; Horanyi, Mihaly; Kohnert, Rick

    . The Mesospheric Aerosol Sampling Spectrometer (MASS) instrument has been launched on two sounding rockets in August, 2007 from Andoya, Norway to detect charged sub-visible aerosol particles in the polar mesosphere. The MASS instrument is designed to collect charged aerosols, cluster ions, and electrons on four pairs of graphite electrodes, three of which are biased with increasing voltage. The design of the MASS instrument was complicated by the short mean free path in the mesosphere. The opening to MASS was deliberately built to increase the mean free path and to reduce the shock wave within the instrument. The design procedure began with aerodynamics simulations of the flow through the instrument using Direct Simulation Monte Carlo (DSMC) in 3-D. The electric fields within the instrument were calculated using a Laplace solver in 3-D. With the aerodynamic and electric field simulations completed, an algorithm was created to find the trajectories of charged aerosols including collisions within MASS. Using this algorithm the collection efficiencies for each electrode was calculated as a function of the charge to mass ratio of the incoming particle. The simulation results have been confirmed experimentally using an Argon RF ion beam. The data from the August launches have been analyzed and the initial results show the MASS instrument operated as expected. Additional studies are underway to determine if there were effects from payload charging or spurious charge generation within the instrument. This project is supported by NASA.

  8. Molecular composition of biogenic secondary organic aerosols using ultrahigh resolution mass spectrometry: comparing laboratory and field studies

    NASA Astrophysics Data System (ADS)

    Kourtchev, I.; Fuller, S. J.; Giorio, C.; Healy, R. M.; Wilson, E.; O'Connor, I. P.; Wenger, J. C.; McLeod, M.; Aalto, J.; Ruuskanen, T. M.; Maenhaut, W.; Jones, R.; Venables, D. S.; Sodeau, J. R.; Kulmala, M.; Kalberer, M.

    2013-11-01

    Numerous laboratory experiments have been performed in an attempt to mimic atmospheric secondary organic aerosol (SOA) formation. However, it is still unclear how close the aerosol particles generated in laboratory experiments resemble atmospheric SOA with respect to their detailed chemical composition. In this study, we generated SOA in a simulation chamber from the ozonolysis of α-pinene and a biogenic volatile organic compound (BVOC) mixture containing α- and β-pinene, Δ3-carene, and isoprene. The detailed molecular composition of laboratory-generated SOA was compared with that of background ambient aerosol collected at a boreal forest site (Hyytiälä, Finland) and an urban location (Cork, Ireland) using direct infusion nanoelectrospray ultrahigh resolution mass spectrometry. Kendrick Mass Defect and Van Krevelen approaches were used to identify and compare compound classes and distributions of the detected species. The laboratory-generated SOA contained a distinguishable group of dimers that was not observed in the ambient samples. The presence of dimers was found to be less pronounced in the SOA from the VOC mixtures when compared to the one component precursor system. The elemental composition of the compounds identified in the monomeric region from the ozonolysis of both α-pinene and VOC mixtures represented the ambient organic composition of particles collected at the boreal forest site reasonably well, with about 70% of common molecular formulae. In contrast, large differences were found between the laboratory-generated BVOC samples and the ambient urban sample. To our knowledge this is the first direct comparison of molecular composition of laboratory-generated SOA from BVOC mixtures and ambient samples.

  9. Multi-wavelength measurements of aerosol optical absorption coefficients using a photoacoustic spectrometer

    NASA Astrophysics Data System (ADS)

    Liu, Qiang; Huang, Hong-Hua; Wang, Yao; Wang, Gui-Shi; Cao, Zhen-Song; Liu, Kun; Chen, Wei-Dong; Gao, Xiao-Ming

    2014-06-01

    The atmospheric aerosol absorption capacity is a critical parameter determining its direct and indirect effects on climate. Accurate measurement is highly desired for the study of the radiative budget of the Earth. A multi-wavelength (405 nm, 532 nm, 780 nm) aerosol absorption meter based on photoacoustic spectroscopy (PAS) invovling a single cylindrical acoustic resonator is developed for measuring the