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1

Elemental Analysis of Sub-Hourly Ambient Aerosol Collections  

Microsoft Academic Search

Simultaneous multielement graphite furnace atomic absorption spectrometry was used to determine Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Sb, Se, and Zn in ambient air sampled at 170 L·min for 30 min and collected as a slurry after dynamic preconcentration. In PM20 samples collected at College Park, MD, results were > 2? above system blank in > 95%

Christopher B. Kidwell; John M. Ondov

2004-01-01

2

Chemical characterization of ambient aerosol collected during the northeast monsoon season over the Arabian Sea: Anions and cations  

Microsoft Academic Search

Ambient aerosol samples were collected over the Arabian Sea during the month of March 1997, aboard the German R\\/V Sonne, as part of the German JGOFS project (Joint Global Ocean Flux Study). This is the third study in a series of analogous measurements taken over the Arabian Sea during different seasons of the monsoon. Dichotomous high volume collector samples were

Anne M. Johansen; Michael R. Hoffmann

2004-01-01

3

Chemical characterization of ambient aerosol collected during the northeast monsoon season over the Arabian Sea: Anions and cations  

Microsoft Academic Search

(1) Ambient aerosol samples were collected over the Arabian Sea during the month of March 1997, aboard the German R\\/V Sonne, as part of the German JGOFS project (Joint Global Ocean Flux Study). This is the third study in a series of analogous measurements taken over the Arabian Sea during different seasons of the monsoon. Dichotomous high volume collector samples

Anne M. Johansen

2004-01-01

4

CCN activation of ambient and "synthetic ambient" urban aerosol  

NASA Astrophysics Data System (ADS)

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 ? [1] were calculated both for the urban and the "synthetic ambient" aerosol and also from the chemical composition. Average ? for the "synthetic ambient" aerosol ranged from 0.20 to 0.30 with an average value of 0.24, while the ? 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].

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

2013-05-01

5

Ambient aerosol sampling using the Aerodyne Aerosol Mass Spectrometer  

Microsoft Academic Search

The Aerodyne Aerosol Mass Spectrometer (AMS) has been designed to measure size-resolved mass distributions and total mass loadings of volatile and semivolatile chemical species in\\/on submicron particles. This paper describes the application of this instrument to ambient aerosol sampling. The AMS uses an aerodynamic lens to focus the particles into a narrow beam, a roughened cartridge heater to vaporize them

Jose L. Jimenez; John T. Jayne; Quan Shi; Charles E. Kolb; Douglas R. Worsnop; Ivan Yourshaw; John H. Seinfeld; Richard C. Flagan; Xuefeng Zhang; Kenneth A. Smith; James W. Morris; Paul Davidovits

2003-01-01

6

Beryllium7 aerosols in ambient air  

Microsoft Academic Search

The aerodynamic size distribution of 7Be in ambient aerosol particles was determined using l-ACFM cascade impactors. The activity distribution of 7Be measured by gamma spectrometry (E? = 477 keV) was largely associated with submicrometer aerosols in the accumulation mode (0.4 to 2.0 ?m). The activity median aerodynamic diameter (AMAD) ranged from 0.76 to 1.18 ?m (average 0.90 ?m), indicating post-condensation

C. Papastefanou; A. Ioannidou

1996-01-01

7

Analytical techniques for ambient sulfate aerosols  

SciTech Connect

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.

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

1981-06-01

8

Analysis of Anions in Ambient Aerosols by Microchip Capillary Electrophoresis  

SciTech Connect

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.

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

2006-10-01

9

DICHOTOMOUS SAMPLER - A PRACTICAL APPROACH TO AEROSOL FRACTIONATION AND COLLECTION  

EPA Science Inventory

Procedures to size fractionate, collect, and analyze ambient concentrations of particulate matter are described. Emphasis is placed on the design and characteristics of the single-stage dichotomous sampler. A new inlet is described that samples aerosol independent of wind speed a...

10

DEVELOPMENT OF A PORTABLE DEVICE TO COLLECT SULFURIC ACID AEROSOL  

EPA Science Inventory

A quantitative, interference-free method for collecting sulfuric acid aerosol on a filter was developed and field tested. Since previous research found that severe losses of sulfuric aicd were caused by ammonia, ambient particulate material, and other interferents, a method was n...

11

GC/MS ANALYSIS OF AMBIENT AIR AEROSOLS IN THE HOUSTON, TEXAS AREA  

EPA Science Inventory

Ambient air aerosols and vapor samples were collected by Radian Corp., Austin, TX. in the Houston, Texas area using three different samplers. A High Volume sampler and dichotomous sampler were used for the collection of particulate matter; vapor-phase organic samples were collect...

12

Rapid Sampling of Individual Organic Aerosol Species in Ambient Air with the Photoionization Aerosol Mass Spectrometer  

Microsoft Academic Search

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. In the work presented here, high-time resolution ambient measurements (3.5 minutes) are achieved by using the Photoionization Aerosol Mass Spectrometer (PIAMS) in conjunction with the mini-Versatile Aerosol Concentration Enrichment System (m-VACES).

Matthew A. Dreyfus; Murray V. Johnston

2008-01-01

13

Collection efficiencies of aerosol samplers for virus-containing aerosols  

Microsoft Academic Search

Collection efficiencies of four bioaerosol samplers (Andersen impactor, AGI-30 impinger, gelatin filter, and nuclepore filter) were evaluated for virus-containing aerosols. Four different bacteriophages were used as surrogates for the mammalian viruses. Results showed that the collection efficiency was significantly affected by the morphology of the virus particles. For hydrophilic viruses, the collection efficiencies of the Andersen impactor, impinger, and gelatin

Chun-Chieh Tseng; Chih-Shan Li

2005-01-01

14

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

NASA Astrophysics Data System (ADS)

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.

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

2012-11-01

15

Hydrogen Peroxide Associated with Ambient Fine Mode, Diesel and Biodiesel Aerosol Particles in Southern California  

Microsoft Academic Search

To investigate the sources of H2O2 generation in fine mode aerosols, a series of measurements on laboratory-generated particles, source materials and ambient particles collected in the Los Angeles area were performed. Ambient fine mode H2O2 levels were associated with transition metals, and were increased by the addition of dithiothreitol, a marker for quinone redox activity. H2O2 levels were sensitive to

Ying Wang; Chuautemoc Arellanes; Suzanne E. Paulson

2011-01-01

16

Hydrogen Peroxide Associated with Ambient Fine-Mode, Diesel, and Biodiesel Aerosol Particles in Southern California  

Microsoft Academic Search

To investigate the sources of H2O2 generation in fine-mode aerosols, a series of measurements on laboratory-generated particles, source materials, and ambient particles collected in the Los Angeles area were performed. Ambient fine-mode H2O2 levels were associated with transition metals, and were increased by the addition of dithiothreitol, a marker for quinone redox activity. H2O2 levels were sensitive to the pH

Ying Wang; Chuautemoc Arellanes; Suzanne E. Paulson

2012-01-01

17

Aerodynamic size association of 7Be in ambient aerosols  

Microsoft Academic Search

The aerodynamic size distribution of 7Be in ambient aerosol particles was determined by using 1-ACFM cascade impactors. The activity distribution of 7Be measured by ?-spectrometry (E? = 447keV), was largely associated with submicron aerosols in the accumulation mode (0.4–2.0 ?m). The activity median aerodynamic diameter, AM AD ranged from 0.76 to 1.18?m (average 0.90?m), indicating post-condensation growth either in the

C. Papastefanou; A. Ioannidou

1995-01-01

18

Subarctic atmospheric aerosol composition: 1. Ambient aerosol characterization  

Microsoft Academic Search

Subarctic 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 68° latitude and 385 m above sea level (m asl), this site is classified as a semicontinuous permafrost mire. Number density, size distribution, cloud condensation nucleus properties, and chemical composition of the

Beth Friedman; Hanna Herich; Lukas Kammermann; Deborah S. Gross; Almut Arneth; Thomas Holst; Daniel J. Cziczo

2009-01-01

19

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

SciTech Connect

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.

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

2005-08-22

20

Mechanisms by Which Ambient Humidity May Affect Viruses in Aerosols  

PubMed Central

Many airborne viruses have been shown to be sensitive to ambient humidity, yet the mechanisms responsible for this phenomenon remain elusive. We review multiple hypotheses, including water activity, surface inactivation, and salt toxicity, that may account for the association between humidity and viability of viruses in aerosols. We assess the evidence and limitations for each hypothesis based on findings from virology, aerosol science, chemistry, and physics. In addition, we hypothesize that changes in pH within the aerosol that are induced by evaporation may trigger conformational changes of the surface glycoproteins of enveloped viruses and subsequently compromise their infectivity. This hypothesis may explain the differing responses of enveloped viruses to humidity. The precise mechanisms underlying the relationship remain largely unverified, and attaining a complete understanding of them will require an interdisciplinary approach.

Yang, Wan

2012-01-01

21

Ambient acid aerosols in rural Nova Scotia  

Microsoft Academic Search

During the summer months, Nova Scotia is downwind of many of the large industrial areas of the eastern United States and central Canada. The studies described here were carried out in the summers of 1983 and 1984 in Antigonish, a small rural town in northeastern Nova Scotia with no local sources. Twenty-four hour samples were collected on Teflon filters using

Truis Smith-Palmer; Byron R. Wentzell

1986-01-01

22

An analysis of diurnal cycles in the mass of ambient aerosols derived from biomass burning and agro-industry  

NASA Astrophysics Data System (ADS)

diurnal cycles in ambient aerosol mass were observed in a rural region of Southeast Brazil where the trace composition of the lower troposphere is governed mainly by emissions from agro-industry. An optical particle counter was used to record size-segregated aerosol number concentrations between 13 May 2010 and 15 March 2011. The data were collected every 10 min and used to calculate aerosol mass concentrations. Aerosol samples were also collected onto filters during daytime (10:00-16:00 local time) and nighttime (20:00-06:00) periods, for subsequent analysis of soluble ions and water-soluble organic carbon. Biomass burning aerosols predominated during the dry winter, while secondary aerosols were most important in the summer rainy season. In both seasons, diurnal cycles in calculated aerosol mass concentrations were due to the uptake of water by the aerosols and, to a lesser extent, to emissions and secondary aerosol formation. In neither season could the observed mass changes be explained by changes in the depth of the boundary layer. In the summer, nighttime increases in aerosol mass ranged from 2.7-fold to 81-fold, depending on particle size, while in the winter, the range was narrower, from 2.2-fold to 9.5-fold, supporting the possibility that the presence of particles derived from biomass burning reduced the overall ability of the aerosols to absorb water.

Caetano-Silva, L.; Allen, A. G.; Lima-Souza, M.; Cardoso, A. A.; Campos, M. L. A. M.; Nogueira, R. F. P.

2013-08-01

23

A technique to expose animals to concentrated fine ambient aerosols.  

PubMed Central

This paper presents the development and evaluation of an ambient particle concentrator for conducting animal inhalation exposure studies. The system utilizes the principle of virtual impactors to concentrate ambient particles in the size range 0.1-2.5 microns (aerodynamic diameter; dp) by drawing them through a series of three virtual impactors. Each impactor contains the majority of ambient fine mass (dp < 2.5 microns aerodynamic diameter) in a bleed flow (minor flow) that is 20% of the total flow entering the virtual impactor. The virtual impactors have been characterized using indoor air samples as test aerosols. Fine mass and sulfate concentrations at the outlet of the concentrating system were compared to the ambient fine mass and sulfate levels, which were determined using Harvard-Marple impactors. In each of the stages, particle concentration was increased by a factor of approximately 3. Thus, an overall concentration factor of about 25-30 was achieved. The main goal of this study was to demonstrate the feasibility of conducting animal exposures using the newly developed ambient fine particle concentrator. Images Figure 1. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6.

Sioutas, C; Koutrakis, P; Burton, R M

1995-01-01

24

Quantifying compositional impacts of ambient aerosol on cloud droplet formation  

NASA Astrophysics Data System (ADS)

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 volume fraction, showing that measurable aging of the aerosol population occurs during the day, on the timescale of a few hours. The mixing state of the aerosol, also showing a consistent diurnal pattern, clearly correlates with a chemical tracer for local combustion sources. Chapter 4 describes results from the GoMACCS field study, in which the CCNc was subsequently deployed on an airborne field campaign in Houston, Texas during August-September, 2006. GoMACCS tested our ability to predict CCN for highly polluted conditions with limited chemical information. Assuming the particles were composed purely of ammonium sulfate, CCN closure was obtained with a 10% overprediction bias on average for CCN concentrations ranging from less than 100 cm-3 to over 10,000 cm-3, but with on average 50% variability. Assuming measured concentrations of organics to be internally mixed and insoluble tended to reduce the overprediction bias for less polluted conditions, but led to underprediction bias in the most polluted conditions. A likely explanation is that the high organic concentrations in the polluted environments depress the surface tension of the droplets, thereby enabling activation at lower soluble fractions.

Lance, Sara

25

LC-MS-MS-TOF analysis of oxygenated organic compounds in ambient aerosol  

NASA Astrophysics Data System (ADS)

Ambient aerosol samples were taken at different sites across Europe. The fine mode aerosol was collected on quartz filters at flow rates of 160 L/min and 500 L/min. These samples were analyzed for organic acids (C>4) by an HPLC system coupled to a hybrid mass spectrometer. The mass spectrometer consists of a quadrupole mass analyzer, a quadrupole collision cell and a time-of-flight mass analyzer (TOF). Analytes were identified by standards when available or MS-MS experiments and exact mass measurements utilizing the high mass resolution of the TOF instrument. Monoterpenes (alpha-pinene, beta-pinene, sabinene, limonene, 3-carene) were ozonolyzed in the laboratory and compared with field samples. Besides the commonly measured organic acids (pinic, pinonic and norpinic acid) sabinic, caric and caronic acid were identified for the first time in ambient aerosol. In addition, nearly all samples showed significant concentrations of newly identified keto dicarboxylic acids (C9 - C12). Laboratory experiments were used to investigate the formation mechanisms of these compounds. By comparing laboratory measurements of wood combustion and field samples from the Eastern Mediterranean region, nitrocatechol was identified as a possible tracer for biomass burning. The data obtained is used to determine the role of biogenic sources in secondary organic aerosol formation.

Roempp, A.; Moortgat, G.

2003-04-01

26

Collection Efficiency of the Aerosol Mass Spectrometer for Chamber-Generated Organic Aerosols  

NASA Astrophysics Data System (ADS)

The collection efficiency (CE) of the Aerodyne Aerosol Mass Spectrometer (AMS) is defined as the fraction of particle mass detected relative to the actual mass or the mass that would be detected in the absence of particle losses. CE is influenced by potential particle losses in the aerodynamic lens (EL), in the vacuum chamber due to particle shape effects (Es), and at the vaporizer surface (Eb) due to particles bouncing prior to desporption and detection (CE=EL*Es*Eb). Previous comparisons of AMS ambient mass concentrations with those measured by collocated instruments indicate that a CE of ~0.5 is appropriate when sampling aerosols in urban areas while other studies have indicated that the CE of accumulation mode particles is driven primarily by losses due to particle bounce at the vaporizer surface. The CE of chamber-generated organic aerosols is less well characterized but is important to the quantitative capacity of the AMS when sampling these aerosols. CE values for chamber-generated organic aerosols were evaluated by comparing AMS measurements against those obtained from a collocated scanning mobility particle sizer and a Sunset semi-continuous organic carbon monitor as well as gravimetric filter measurements. More than thirty reactions were conducted over the course of a year to build a large dataset to identify trends in CE values. Throughout this set of experiments, the parent hydrocarbon and oxidant pair were also highly varied to ensure diversity in SOA composition in order to investigate the impact of chemical composition on CE. Dioctyl sebacate (DOS) particles were intermittently analyzed throughout the set of experiments to ensure stability of the AMS operating conditions and to rule out changes in AMS conditions as the cause of observed CE values. DOS was chosen due to its ability to form spherical, liquid particles which results in maximal CE. Finally, for both chamber-generated and standard aerosols, measurements were made at steady-state when concentrations were stable and varied less than 5% on average. CE values calculated from this set of experiments varied widely with the CE of DOS being one on average. The CE of chamber-generated aerosols and other aerosol standards were lower with an overall average CE of 0.39+0.26 from all experiments. The entire set of CE values was compared with available and known SOA parameters including aerosol concentration, calculated aerosol density and OM/OC ratio, AMS mass spectral characteristics including the relative contributions of m/z 44 (i.e., f44) and m/z 57 (f57) to organic aerosol, as well as the relative contribution of sulfate and nitrate to aerosol mass in each case. CE has very low correlation with each of these parameters except f44 and f57 with which CE is only weakly correlated. However, the correlation of CE is much stronger (r 2=0.77) when compared against the f57/f44 ratio. These results appear to indicate that composition plays a critical role in determining the CE of organic aerosols in the AMS.

Docherty, K. S.; Jaoui, M.; Beaver, M. R.; Offenberg, J. H.; Lewandowski, M.; Kleindienst, T. E.

2011-12-01

27

WOODSMOKE AND MOTOR VEHICLE CONTRIBUTION TO AMBIENT AEROSOL MUTAGENICITY  

EPA Science Inventory

A receptor model analysis of the mutagenicity of ambient fine particles in air samples collected under EPA's Integrated Air Cancer Project has been performed. he analysis was based on multiple linear regression, using measured concentrations of inorganic chemical elements which a...

28

On-line analysis of ambient air aerosols using laser-induced breakdown spectroscopy  

Microsoft Academic Search

Laser-induced breakdown spectroscopy is developed for the detection of aerosols in ambient air, including quantitative mass concentration measurements and size\\/composition measurements of individual aerosol particles. Data are reported for ambient air aerosols containing aluminum, calcium, magnesium and sodium for a 6-week sampling period spanning the Fourth of July holiday period. Measured mass concentrations for these four elements ranged from 1.7

J. E. Carranza; B. T. Fisher; G. D. Yoder; D. W. Hahn

2001-01-01

29

Ambient aerosol concentrations of sugars and sugar-alcohols at four different sites in Norway  

Microsoft Academic Search

Sugars and sugar-alcohols are demonstrated to be important constituents of the ambient aerosol water-soluble organic carbon fraction, and to be tracers for primary biological aerosol particles (PBAP). In the present study, levels of four sugars (fructose, glucose, sucrose, trehalose) and three sugar-alcohols (arabitol, inositol, mannitol) in ambient aerosols have been quantified using a novel HPLC\\/HRMS-TOF (High Performance Liquid Chromatography in

K. E. Yttri; C. Dye; G. Kiss

2007-01-01

30

A new technique for collecting ambient diesel particles for bioassays.  

PubMed

This paper describes a new application of a viable aerosol sampler, the Liquid Electrostatic Aerosol Precipitator (LEAP), for the collection of diesel particles for bioassays of pulmonary toxicity and mutagenicity or carcinogenicity. Currently used methods (filtration, dry electrostatic precipitation) cause agglomeration of particles and increases in particle size up to twenty-fold, which may alter particle toxicity significantly. Collection of diesel particles with the LEAP preserved submicronic particle size. Differences in chemical composition of extracts of surface adsorbents as compared to particles collected on filters also were observed. This technique may be applicable for collection of other types of combustion products or oil mists that agglomerate when collected by filtration. PMID:2438921

Hallock, M F; Smith, T J; Hammond, S K; Beck, B D; Brain, J D

1987-05-01

31

Biogenic contribution to PM-2.5 ambient aerosol from radiocarbon measurements  

NASA Astrophysics Data System (ADS)

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.

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

2003-04-01

32

Bias in Filter-Based Aerosol Light Absorption Measurements Due to Organic Aerosol Loading: Evidence from Ambient Measurements  

Microsoft Academic Search

During the 2006 Texas Air Quality Study\\/Gulf of Mexico Atmospheric Composition and Climate Study (TexAQS\\/GoMACCS 2006) a filter-based (Particle Soot Absorption Photometer, or PSAP) and a photoacoustic-based aerosol light absorption technique were deployed and here the data are compared. The level of agreement between the two techniques with ambient aerosol depended on the abundance of organic aerosol (OA), with the

Daniel A. Lack; Christopher D. Cappa; Tahllee Baynard; Paola Massoli; Berko Sierau; Timothy S. Bates; Patricia K. Quinn; Edward R. Lovejoy; A. R. Ravishankara

2008-01-01

33

Quantitative chemical analysis of ambient organic aerosols using high-resolution time-of-flight aerosol mass spectrometry  

NASA Astrophysics Data System (ADS)

Atmospheric aerosols are important due to their effects on health, climate, visibility, and ecosystems. Organic aerosols (OA) comprise a large fraction of the submicron particle mass, yet their total composition, sources, and processing are not well understood. This thesis focuses on the composition and sources in order to improve the current state of knowledge on ambient OA. To analyze the composition of the total OA mass, a new elemental analysis (EA) technique for organic species (CHNO) was developed for use with the high-resolution Aerodyne Aerosol Mass Spectrometer (AMS). The method is calibrated with laboratory standards and enables fast on-line analysis (˜10 seconds) of OA from organic/inorganic mixtures. Additionally, the required sample size is reduced to ˜1 ng, approximately six orders of magnitude less than standard techniques. Elemental ratios for the total organic mass, i.e. oxygen/carbon (O/C), in addition to the organic mass to organic carbon ratio (OM/OC), are estimated with high precision (+/- 3% in the absence of air) but lower accuracy. The method is applied to both ambient and source aerosols, yielding similar results within the different OA types sampled. To characterize the sources of OA from within an urban Megacity, measurements were collected from a ground site within the Mexico City Metropolitan Area during the MILAGRO/MCMA-2006 field campaign. Standard AMS analyses, positive matrix factorization, elemental analysis, comparison with model output, and comparative analyses from different time periods, were applied to the data. The dominant OA sources identified were primary hydrocarbon-like, primary biomass burning, and secondary oxygenated OA, which were similar to source apportionment results from the chemical mass balance method using organic molecular markers. The oxygenated OA accounts for almost half of the OA on average. Biomass burning OA was heavily influenced by forest fires in the surrounding mountains, accounting for 15-23% of the OA on average, which is less than was identified in the air masses above the city. Overall, the forest fires are estimated to contribute 7-9% of the fine PM at T0 during MILAGRO and 2-3% of the fine PM as an annual average. In addition, carbon-14 analysis indicates a significant portion of the urban OA originates from modern carbon sources as has been reported for other urban locations. In summary, when compared to the 2004 Mexico City emissions inventory, the urban primary aerosol mass is underestimated by a factor of ˜3.5 (and it is ˜17x lower than afternoon concentrations when secondary species are included) and the wildfire contribution by a factor of ˜20.

Aiken, Allison Carol

34

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

NASA Astrophysics Data System (ADS)

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 experiment course. The SOA was simultaneously characterized by an aerosol mass spectrometer (AMS). The ACM-GC-MS results will be compared with PMF analysis of the AMS organic aerosol. The correlation of specific compounds with PMF factors will be discussed together with future applications of the ACM-GC-MS system for ambient aerosol measurements. Acknowledgement This work was supported by the US Environmental Protection Agency (EPA Grant No. RD-83107701-0) and the Department of Energy (DOE SBIR Grant No. DE-FG02-05ER84269). References Intergovernmental Panel on Climate Change (IPCC): Climate Change 2007, Cambridge University Press, UK, 2007 Hallquist et al., The formation, properties and impact of secondary organic aerosol: current and emerging issues, Atmos. Chem. Phys, Vol.9, 5155-5236, 2009

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

2010-05-01

35

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 ...

36

Collection of Aerosolized Human Cytokines Using Teflon(R) Filters  

PubMed Central

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 exhaled breath samples.

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

2012-01-01

37

Combustion characteristics of water-insoluble elemental and organic carbon in size selected ambient aerosol particles  

NASA Astrophysics Data System (ADS)

Combustion of elemental carbon (EC) and organic carbon (OC) contained in ambient aerosol matter was explored using scanning electron microscopy (SEM) in combination with energy dispersive X-ray analysis (EDX). To ease identification of the particles of interest and to avoid or at least reduce interaction with simultaneously sampled inorganic oxides and salts, the approach used in this work differed in two ways from commonly applied procedures. First, rather than using a mixture of particles of vastly different sizes, as in PM10 or PM2.5, aerosol matter was collected in a 5-stage impactor. Second, the water soluble fraction of the collected matter was removed prior to analysis. Diesel soot particles, which appeared in the well-known form of chain-type aggregates, constituted the major fraction of EC. In contrast, OC containing particles were observed in a variety of shapes, including a sizable amount of bioaerosol matter appearing mostly in the size range above about 1 µm. During heating in ambient air for 1 h, diesel soot particles were found to be stable up to 480°C, but complete combustion occurred in a narrow temperature interval between about 490 and 510°C. After diesel soot combustion, minute quantities of ''ash'' were observed in the form of aggregated tiny particles with sizes less than 10 nm. These particles could be due to elemental or oxidic contaminants of diesel soot. Combustion of OC was observed over a wide range of temperatures, from well below 200°C to at least 500°C. Incompletely burnt bioaerosol matter was still found after heating to 600°C. The results imply that the EC fraction in aerosol matter can be overestimated significantly if the contribution of OC to a thermogram is not well separated.

Wittmaack, K.

2005-04-01

38

Combustion characteristics of water-insoluble elemental and organic carbon in size selected ambient aerosol particles  

NASA Astrophysics Data System (ADS)

Combustion of elemental carbon (EC) and organic carbon (OC) contained in ambient aerosol matter was explored using scanning electron microscopy (SEM) in combination with energy dispersive X-ray analysis (EDX). To ease identification of the particles of interest and to avoid or at least reduce interaction with simultaneously sampled inorganic oxides and salts, the approach used in this work differed in two ways from commonly applied procedures. First, rather than using a mixture of particles of vastly different sizes, as in PM10 or PM2.5, aerosol matter was collected in a 5-stage impactor. Second, the water soluble fraction of the collected matter was removed prior to analysis. Diesel soot particles, which appeared in the well-known form of chain-type aggregates, constituted the major fraction of EC. In contrast, OC containing particles were observed in a variety of shapes, including a sizable amount of bioaerosol matter appearing mostly in the size range above about 1 µm. During heating in ambient air for 1h, diesel soot particles were found to be stable up to 470°C, but complete combustion occurred in a narrow temperature interval between about 480 and 510°C. After diesel soot combustion, minute quantities of "ash" were observed in the form of aggregated tiny particles with sizes less than 10 nm. These particles could be due to elemental or oxidic contaminants of diesel soot. Combustion of OC was observed over a wide range of temperatures, from well below 200°C to at least 500°C. Incompletely burnt bioaerosol matter was still found after heating to 600°C. The results imply that the EC fraction in aerosol matter can be overestimated significantly if the contribution of OC to a thermogram is not well separated.

Wittmaack, K.

2005-07-01

39

Hygroscopic Characteristics of Organic Laden Ambient Aerosols in Yosemite National Park  

Microsoft Academic Search

Water absorption by inorganic compounds can be modeled with some degree of certainty; however, water uptake by ambient organic aerosols remains speculative. To improve the understanding of organic hygroscopicity, an aerosol characterization study was conducted at Yosemite National Park, California, starting in July and ending in the first week of September 2002. High time resolution measurement (15-minute time increments) of

W. C. Malm; D. E. Day; S. M. Kreidenweis; J. L. Collett; C. M. Carrico; T. Lee; G. Bench; J. Carrillo

2003-01-01

40

Quantitative estimates of the volatility of ambient organic aerosol  

Microsoft Academic Search

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 tan- dem 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 parti- tioning

C. D. Cappa; J. L. Jimenez

2010-01-01

41

Mass Absorption Cross-Section of Ambient Black Carbon Aerosol in Relation to Chemical Age  

Microsoft Academic Search

Three differing techniques were used to measure ambient black carbon (BC) aerosols in downtown Toronto through 20 December 2006 to 23 January 2007. These techniques were thermal analysis, as performed by a Sunset Labs OCEC Analyzer (OCEC); light attenuation, as performed by an Aethalometer (AE); and photoacoustic analysis, as performed by a Photoacoustic Instrument (PA). These measurements of ambient PM2.5

A. Knox; G. J. Evans; J. R. Brook; X. Yao; C.-H. Jeong; K. J. Godri; K. Sabaliauskas; J. G. Slowik

2009-01-01

42

Composition, particle size, and source of ambient aerosol in Alachua County, Florida  

NASA Astrophysics Data System (ADS)

Size fractionated samples of ambient particulate matter were collected using a Micro-orifice uniform deposit impactor (MOUDI) and a Dichotomous sampler at three sites within Alachua County, Florida, during the year 2000--2001. Particles from several major sources were also collected with a MOUDI. These samples were chemically analyzed for principal ions, carbon, and elements to help determine the major sources of these aerosols through the use of a chemical mass balance model (CMB8). Capillary electrophoresis, PIXE, and CNHS analyzer were used for ion analysis, elemental analysis, and carbon analysis, respectively. Variations by sampling site and season were also studied. Results revealed that ambient particles had a bimodal distribution with a major peak of 0.32 to 0.56 mum in the fine mode, and 3.2 to 5.6 mum in the coarse mode. PM 10 particles, averaged over all sites and seasons, consisted of 44% ions, 20% carbon, and 25% elements. Transportation and marine particles were major sources of fine particles for every season. Residential wood burning, cement plant, distillate oil furnace, and coal-fired power plant were additional sources in the spring. In summer, wood burning also became a major source. There were several sources of coarse particles. The main sources were marine, cement plant/unpaved road, transportation, asphalt plant, distillate oil furnace, soil, and agricultural field burning. Site variation and diurnal variation were inconsistent and mainly depended on the meteorology of the day.

Chuaybamroong, Paradee

43

Aerodynamic size associations of natural radioactivity with ambient aerosols  

SciTech Connect

The aerodynamic size of /sup 214/Pb, /sup 212/Pb, /sup 210/Pb, /sup 7/Be, /sup 32/P, /sup 35/S (as SO/sub 4//sup 2 -/), and stable SO/sub 4//sup 2 -/ was measured using cascade impactors. The activity distribution of /sup 212/Pb and /sup 214/Pb, measured by alpha spectroscopy, was largely associated with aerosols smaller than 0.52 ..mu..m. Based on 46 measurements, the activity median aerodynamic diameter of /sup 212/Pb averaged 0.13 ..mu..m (sigma/sub g/ = 2.97), while /sup 214/Pb averaged 0.16 ..mu..m (sigma/sub g/ = 2.86). The larger median size of /sup 214/Pb was attributed to ..cap alpha..-recoil depletion of smaller aerosols following decay of aerosol-associated /sup 218/Po. Subsequent /sup 214/Pb condensation on all aerosols effectively enriches larger aerosols. /sup 212/Pb does not undergo this recoil-driven redistribution. Low-pressure impactor measurements indicated that the mass median aerodynamic diameter of SO/sub 4//sup 2 -/ was about three times larger than the activity median diameter /sup 212/Pb, reflecting differences in atmospheric residence times as well as the differences in surface area and volume distributions of the atmospheric aerosol. Cosmogenic radionuclides, especially /sup 7/Be, were associated with smaller aerosols than SO/sub 4//sup 2 -/ regardless of season, while /sup 210/Pb distributions in summer measurements were similar to sulfate but smaller in winter measurements. Even considering recoil following /sup 214/Po ..cap alpha..-decay, the avervage /sup 210/Pb labeled aerosol grows by about a factor of two during its atmospheric lifetime. The presence of 5 to 10% of the /sup 7/Be on aerosols greater than 1 ..mu..m was indicative of post-condensation growth, probably either in the upper atmosphere or after mixing into the boundary layer.

Bondietti, E.A.; Papastefanou, C.; Rangarajan, C.

1986-04-01

44

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  

Microsoft Academic Search

Recent observations in ambient PM2.5 of 2-methylthreitol, 2-methylerythritol and 2-methylglyceric acid, proposed isoprene oxidation products, suggest the contribution of isoprene to SOA formation, long thought to be relatively unimportant, should be reexamined. To address this issue, an isoprene\\/NOX\\/air mixture was irradiated in a flow reactor smog chamber in both the absence and presence of SO2 to measure the SOA yield

E. O. Edney; T. E. Kleindienst; M. Jaoui; M. Lewandowski; J. H. Offenberg; W. Wang; M. Claeys

2005-01-01

45

Temporal and spatial variation of morphological descriptors for atmospheric aerosols collected in Mexico City  

NASA Astrophysics Data System (ADS)

We present an analysis of morphological characteristics of atmospheric aerosol collected during the MILAGRO (Megacity Initiative: Local and Global Research Observations) field campaign that took place in Mexico City in March 2006. The sampler was installed on the Aerodyne mobile laboratory. The aerosol samples were collected on nuclepore clear polycarbonate filters mounted in Costar pop-top membrane holders. More than one hundred filters were collected at different ground sites with different atmospheric and geographical characteristics (urban, sub-urban, mountain-top, industrial, etc.) over a month period. Selected subsets of these filters were analyzed for aerosol morphology using a scanning electron microscope and image analysis techniques. In this study we investigate spatial and temporal variations of aerosol shape descriptors, morphological parameters, and fractal dimension. We also compare the morphological results with other aerosol measurements such as aerosol optical properties(scattering and absorption) and size distribution data. Atmospheric aerosols have different morphological characteristics depending on many parameters such as emission sources, atmospheric formation pathways, aging processes, and aerosol mixing state. The aerosol morphology influences aerosol chemical and mechanical interactions with the environment, physical properties, and radiative effects. In this study, ambient aerosol particles have been classified in different shape groups as spherical, irregularly shaped, and fractal-like aggregates. Different morphological parameters such as aspect ratio, roundness, feret diameter, etc. have been estimated for irregular shaped and spherical particles and for different kinds of soot particles including fresh soot, collapsed and coated soot. Fractal geometry and image processing have been used to obtain morphological characteristics of different soot particles. The number of monomers constituting each aggregate and their diameters were measured and used to estimate an ensemble three-dimensional (3-d) fractal dimension. One-dimensional (1-d) and two-dimensional (2-d) fractal geometries have been measured using a power-law scaling relationship between 1-d and 2-d properties of projected images. Temporal variations in fractal dimension of soot-like aggregates have been observed at the mountaintop site and spatial variation of fractal dimension and other morphological descriptors of different shaped particles have been investigated for the different ground sites.

China, S.; Mazzoleni, C.; Dubey, M. K.; Chakrabarty, R. K.; Moosmuller, H.; Onasch, T. B.; Herndon, S. C.

2010-12-01

46

Ambient aerosol and its carbon content in Gainesville, a mid-scale city in Florida.  

PubMed

Ambient aerosols were collected during 2000-2001 in Gainesville, Florida, using a micro-orifice uniform deposit impactor (MOUDI) to study mass size distribution and carbon composition. A bimodal mass distribution was found in every sample with major peaks for aerosols ranging from 0.32 to 0.56 microm, and 3.2 to 5.6 microm in diameter. The two distributions represent the fine mode (<2.5 microm) and the coarse mode (>2.5 microm) of particle size. Averaged over all sites and seasons, coarse particles consisted of 15% carbon while fine particles consisted of 22% carbon. Considerable variation was noted between winter and summer seasons. Smoke from fireplaces in winter appeared to be an important factor for the carbon, especially the elemental carbon contribution. In summer, organic carbon was more abundant. The maximum secondary organic carbon was also found in this season (7.0 microg m(-3)), and the concentration is between those observed in urban areas (15-20 microg m(-3)) and in rural areas (4-5 microg m(-3)). However, unlike in large cities where photochemical activity of anthropogenic emissions are determinants of carbon composition, biogenic sources were likely the key factor in Gainesville. Other critical factors that affect the distribution, shape and concentration were precipitation, brushfire and wind. PMID:17160439

Chuaybamroong, Paradee; Cayse, Kimberleigh; Wu, Chang-Yu; Lundgren, Dale A

2006-12-08

47

Chemical characteristics of ambient aerosols contributed by cooking process at Noorpur village near Delhi (India)  

NASA Astrophysics Data System (ADS)

Combustion of fuels such as wood, crop residue and dung cakes etc. is one of the major sources of air pollution in developing countries. These fuels are still used commonly for cooking purpose in rural India. This study investigates the chemical composition of the ambient aerosols during cooking hours at a village called Noorpur (28.470 N, 77.030 E) which lies near Delhi city. Aerosol 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 samples were collected on 8 hourly basis using Teflon filters. The water extract of these filters was analyzed for major anions (F-, Cl-, NO3-, SO42-) and major cations (Na+, NH4+, K+, Ca2+ Mg2+) by ion chromatography (Metrohm 883 Basic IC Plus). Results highlighted that cooking process contributed significant amount of SO42- and K+.. Biomass burning is considered as a potential source of K+ in air. The high concentration of SO42- might be due to oxidation of SO2 contributed by the combustion of dung cakes. Further, the detailed results will be discussed during the conference.

Singh, Sudha; Kumar, Bablu; Gupta, Gyan Prakash; Kulshrestha, U. C.

2013-05-01

48

Comparison of two particle-size spectrometers for ambient aerosol measurements  

Microsoft Academic Search

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 the full range of the fine fraction (diameter <2.5?m) of the atmospheric aerosol, two instruments, the mobile aerosol

Th. Tuch; A. Mirme; E. Tamm; J. Heinrich; J. Heyder; P. Brand; Ch. Roth; H. E. Wichmann; J. Pekkanen; W. G. Kreyling

2000-01-01

49

Characterization of ambient aerosol composition and formation mechanisms and development of quantification methodologies utilizing ATOFMS  

NASA Astrophysics Data System (ADS)

Aerosols are solid or liquid particles suspended in the air. They are generated from a range of natural and anthropogenic sources. Aerosols also experience various reactions such as photo-oxidation and aqueous-phase processing, which constantly change their physical and chemical properties. Therefore, in order to determine the emission inventory, it is important to study aerosol reactions and transformation mechanisms in ambient atmosphere. The research described in this dissertation aimed to characterize temporal, spatial, and seasonal variations on ambient aerosol chemical compositions and formation mechanisms. The results contribute to the understanding of air pollution, climate change, and human health problems, and to devising necessary strategies and policies to resolve these problems. The main experimental technique utilized in the current work is Aerosol time-of-flight mass spectrometry (ATOFMS). It measures the size and chemical composition of individual particles in real-time, and can thus provide high time resolution information on aerosol mixing states, reaction mechanisms, and sources. Continuous ATOFMS measurements have been conducted to study the ambient aerosol properties in several highly polluted regions of California, including the Fresno and Angiola area and the Riverside area. The results provide important insights on the characteristics, distinct diurnal temporal trends, and seasonal variations of aerosols in both urban and rural locations. The second focus of this dissertation is on the quantification capability of ATOFMS, which had been limited by several factors including the size-dependant particle transmission loss and shot-to-shot variability of the desorption/ionization laser. It is demonstrated that, by scaling the ATOFMS measurements using the results from an aerodynamic particle sizer (APS) or a micro-orifice uniform deposit impactor (MOUDI) measurements, it is possible to obtain high temporal resolution mass concentrations from ATOFMS that are in very good agreements with standard beta attenuation monitor mass concentrations. This development substantially improves the quantitative capability of ATOFMS, and will be useful in future application of ATOFMS to study aerosol source apportionment.

Qin, Xueying

50

Oxidation of ambient biogenic secondary organic aerosol by hydroxyl radicals: Effects on cloud condensation nuclei activity  

NASA Astrophysics Data System (ADS)

Changes in the hygroscopicity of ambient biogenic secondary organic aerosols (SOA) due to controlled OH oxidation were investigated at a remote forested site at Whistler Mountain, British Columbia during July of 2010. Coupled photo-oxidation and cloud condensation nuclei (CCN) experiments were conducted on: i) ambient particles exposed to high levels of gas-phase OH, and ii) the water-soluble fraction of ambient particles oxidized by aqueous-phase OH. An Aerodyne Aerosol Mass Spectrometer (AMS) monitored the changes in the chemical composition and degree of oxidation (O:C ratio) of the organic component of ambient aerosol due to OH oxidation. The CCN activity of size-selected particles was measured to determine the hygroscopicity parameter ($\\kappa$org,CCN) for particles of various degrees of oxygenation. In both cases, the CCN activity of the oxidized material was higher than that of the ambient particles. In general, $\\kappa$org,CCN of the aerosol increases with its O:C ratio, in agreement with previous laboratory measurements.

Wong, J. P. S.; Lee, A. K. Y.; Slowik, J. G.; Cziczo, D. J.; Leaitch, W. R.; Macdonald, A.; Abbatt, J. P. D.

2011-11-01

51

Contribution to bacterial mutagenicity from nitro-pah compounds in ambient aerosols  

NASA Astrophysics Data System (ADS)

To demonstrate a method for the identification of mutagenic components in organic fractions of ambient aerosols, the mutagenic activity was studied in samples collected simultaneously for six consecutive days during the summer of 1931 at an urban site and a suburban site in southeast Michigan. The filter samples were extracted with dichloromethane and fractionated by thin layer chromatography (TLC) into sixteen fractions. The individual TLC fractions were then examined by the Ames test using tester strains TA98, TA98NR and TA98DNP 6. Similar daily variations in the activity and the mutagenicity profiles of the TLC fractions occurred at both sites. In samples collected from both locations, approximately half of the mutagenic activity was found in the four most polar fractions of the particulate extracts. The remaining mutagenic activity was distributed among the less polar fractions where PAH, nitro-PAH and dinitro-PAH would be eluted. The mutagenic activity in all fractions decreased sharply when tested with two nitroreductase deficient tester strains, TA98NR and TA98DNP 6, indicating that the mutagens (especially those in the polar fractions) were nitro-substituted polycyclic aromatic hydrocarbon compounds. Three nitro compounds, 1-nitropyrene, 1,6-dinitropyrene and 1,8-dinitropyrene were detected by high performance liquid chromatography (HPLC) but could account for no more than 3% of the total airborne mutagenicity. A National Bureau of Standards' Ambient Particulate Sample (SRM No. 1649), collected for a long sampling period of 18 months, differed markedly from the urban and suburban Michigan samples in its mutagenicity profile.

Siak, J.; Chan, T. L.; Gibson, T. L.; Wolff, G. T.

52

Collection of Aerosol Particles by Electrostatic Droplet Spray Scrubbers  

Microsoft Academic Search

Theoretical calculations and experimental measurements show that the collection of small aerosol particles (0.05 to 5 micron diameter range) by water droplets in spray scrubbers can be substantially increased by electrostatically charging the droplets and particles to opposite polarity. Measurements with a 140 acfm two chamber spray scrubber (7 seconds gas residence time) showed an increase in the overall particle

Michael J. Pilat

1975-01-01

53

DESIGN, FABRICATION AND TESTING OF AMBIENT AEROSOL SAMPLER INLETS  

EPA Science Inventory

Data are presented on the wind tunnel performances of two prototype Inhalable Particulate Matter (IPM) inlets designed for use with a dichotomous sampler. One was developed at the Aerosol Science Laboratory (ASL) Colorado State University, while the other was developed in an inde...

54

An Aerosol Chemical Speciation Monitor (ACSM) for Routine Monitoring of the Composition and Mass Concentrations of Ambient Aerosol  

Microsoft Academic Search

We present a new instrument, the Aerosol Chemical Speciation Monitor (ACSM), which routinely characterizes and monitors the mass and chemical composition of non-refractory submicron particulate matter in real time. Under ambient conditions, mass concentrations of particulate organics, sulfate, nitrate, ammonium, and chloride are obtained with a detection limit <0.2 ?g\\/m for 30 min of signal averaging. The ACSM is built upon

N. L. Ng; S. C. Herndon; A. Trimborn; M. R. Canagaratna; P. L. Croteau; T. B. Onasch; D. Sueper; D. R. Worsnop; Q. Zhang; Y. L. Sun; J. T. Jayne

2011-01-01

55

Collecting aerosol in airflow with a magnetically stabilized fluidized bed.  

PubMed

A magnetically stabilized fluidized bed (MSB) is a highly efficient filter that takes the advantage of both fluidized beds and fixed beds. This paper presents the research to collect aerosol in airflow with a MSB. The filtering model of MSB is established with its parameters including magnetic field intensity, gas superficial velocity, average grain-size, and bed height on the collection efficiency of MSB. The model is verified by experiments. PMID:11723940

Gui, K T; Zhang, H; Shi, M H; Xu, Y Q

2001-10-01

56

Combustion characteristics of water-insoluble elemental and organic carbon in size selected ambient aerosol particles  

Microsoft Academic Search

Combustion of elemental carbon (EC) and organic carbon (OC) contained in ambient aerosol matter was explored using scanning electron microscopy (SEM) in combination with energy dispersive X-ray analysis (EDX). To ease identification of the particles of interest and to avoid or at least reduce interaction with simultaneously sampled inorganic oxides and salts, the approach used in this work differed in

K. Wittmaack

2005-01-01

57

Characteristics of trace elements in aerosols collected in Northern Tunisia  

NASA Astrophysics Data System (ADS)

In order to investigate the chemical characteristics of atmospheric aerosols, the sources and variability of atmospheric inputs, aerosols samples were collected during April 2006 and June 2007 in the coastal area of Boumhel, Tunisia. The samples were analysed for thirteen elements including Ca, Fe, Al, Si, Ti, Mg, Mn, K, Na, Cl, S, Zn and Pb using a wavelength dispersive X-ray fluorescence spectrometry. All elements measured in the aerosols of Boumhel revealed differences between the two seasons: the concentrations of all elements were the highest in June and the lowest in April due to the importance of meteorological conditions. The cascade impactor provided mass distributions indicate that Al, Fe, Si, Ti, Na, Cl and S are concentrated in coarse particles. The enrichment factors (EFs) of all elements indicate that Al, Fe, Si, Ca and Ti are mainly derived from soil sources. Na, S and Cl are mostly due to sea salts.

Ellouz, F.; Masmoudi, M.; Quisefit, J. P.; Medhioub, K.

58

Ambient organic aerosols: Where they come from, and where they are going (some more slowly than others)  

NASA Astrophysics Data System (ADS)

Although the inorganic component of ambient aerosols is relatively well understood, many questions remain concerning organic aerosols. One is whether some organic aerosols are kinetically limited from acting as cloud condensation nuclei (CCN). In the summer of 2006, we measured the rate of cloud droplet formation on atmospheric particles sampled at four sites across the United States. Overall, most ambient CCN grew at a rate similar to ammonium sulfate, but approximately one third grew more slowly. We made similar measurements in the summer of 2007 at a coastal California site. We observed persistent bimodal diameter spectra, and the slowly-growing mode contained 10-25% of all particles and had mass accommodation coefficients 10 -- 30 times smaller than that measured for ammonium sulfate. While much aerosol hygroscopicity data is available at lower relative humidities (RH) and at supersaturations (RH> 100%), relatively little data is available at high RH (99.2--99.9%). We measured the size of droplets at high RH that had formed on particles composed of one of seven compounds with dry diameters between 0.1 and 0.5 mum. The hygroscopicity of the inorganic compounds was relatively constant with both RH and Dwet. In contrast, most organics, particularly sodium dodecyl sulfate (SDS), showed a slight to mild increase in hygroscopicity with Dwet. This suggests that surface partitioning tends to cancel out the increase in hygroscopicity due to surface tension reduction, increasingly so at low Dwet. SDS hygroscopicity did not decrease at lower RH, as would be expected if micelles formed. These results suggest that surface-activity parameters obtained from macroscopic solutions with organic solutes may be inappropriate for calculations of the hygroscopicity of micron-sized droplets. Finally, we examined possible sources of ambient organic aerosols. A new analytical technique for aersol water-soluble organic carbon (WSOC) was applied to samples collected at four sites across the United States. It involves the separation of samples by size-exclusion chromatography, followed by the measurement of the 13C content. We observed a pattern of 13C depletion in molecules with larger hydrodynamic diameters in Tennessee, indicating that oligomerization reactions produce secondary aerosol where biogenic emissions such as terpenes are prevalent.

Ruehl, Christopher R.

59

Technical Note: The application of an improved gas and aerosol collector for ambient air pollutants in China  

NASA Astrophysics Data System (ADS)

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 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%). When applied in two major field campaigns (rural and coastal sites) in China, the GAC-IC system provided high-quality data in ambient conditions even under high loadings of pollutants. Its measurements were highly correlated with data by other commercial instruments such as the SO2 analyzer (43c, Thermo-Fisher, USA; R2 as 0.96), the HONO analyzer (LOPAP, Germany; R2 as 0.91 for nighttime samples), a filter sampler (Tianhong, China; R2 as 0.86 for SO42-), and Aerosol Mass Spectrometer (AMS, Aerodyne, USA; R2 above 0.77 for major species) over a wide range of concentrations. Through the application of the GAC-IC system, it was identified that 70% of chloride and nitrate by the filter method could be lost during daytime sampling due to high temperature in the rural site of Kaiping. In Changdao field campaign (coastal site) the comparison with the measurements by the GAC-IC suggested that the collection efficiency of AMS might be greatly influenced by high relative humidity (RH) especially in coastal or marine environment. Through laboratory and field studies, this instrument is proved highly reliable, which is particularly useful in future intensive campaigns or long-term monitoring stations to study various environmental issues such as secondary aerosol and haze formation, as well as climate change.

Dong, H.-B.; Zeng, L.-M.; Hu, M.; Wu, Y.-S.; Zhang, Y.-H.; Slanina, J.; Zheng, M.; Wang, Z.-F.; Jansen, R.

2012-03-01

60

Portable Aerosol Contaminant Extractor  

DOEpatents

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.

Carlson, Duane C. (N. Augusta, SC); DeGange, John J. (Aiken, SC); Cable-Dunlap, Paula (Waynesville, NC)

2005-11-15

61

Comparison of aerosol and bioaerosol collection on air filters.  

PubMed

Air filters efficiency is usually determined by non-biological test aerosols, such as potassium chloride particles, Arizona dust or di-ethyl-hexyl-sebacate (DEHS) oily liquid. This research was undertaken to asses, if application of non-biological aerosols reflects air filters capacity to collect particles of biological origin. The collection efficiency for non-biological aerosol was tested with the PALAS set and ISO Fine Test Dust. Flow rate during the filtration process was 720 l/h, and particles size ranged 0.246-17.165 ?m. The upstream and downstream concentration of the aerosol was measured with a laser particle counter PCS-2010. Tested bioaerosol contained 4 bacterial strains of different shape and size: Micrococcus luteus,Micrococcus varians, Pseudomonas putida and Bacillus subtilis. Number of the biological particles was estimated with a culture-based method. Results obtained with bioaerosol did not confirmed 100% filters efficiency noted for the mineral test dust of the same aerodynamic diameter. Maximum efficiency tested with bacterial cells was 99.8%. Additionally, cells reemission from filters into air was also studied. Bioaerosol contained 3 bacterial strains: Micrococcus varians, Pseudomonas putida and Bacillus subtilis. It was proved that the highest intensity of the reemission process was during the first 5 min. and reached maximum 0.63% of total number of bacteria retained in filters. Spherical cells adhered stronger to the filter fibres than cylindrical ones. It was concluded that non-biological aerosol containing particles of the same shape and surface characteristics (like DEHS spherical particles) can not give representative results for all particles present in the filtered air. PMID:22523449

Miaskiewicz-Peska, Ewa; Lebkowska, Maria

2011-09-17

62

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

SciTech Connect

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.

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

63

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

PubMed

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 ?g 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. PMID:23981648

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

2013-08-24

64

Source Apportionment Methods Applied to the Determination of the Origin of Ambient Aerosols That Affect Visibility in Forested Areas.  

National Technical Information Service (NTIS)

An aerosol characterization, visibility, and receptor modeling study was conducted in the Shenandoah Valley, VA between July 14 and August 15, 1980. The objectives of this study were to: (1) determine the origin of the ambient particles, (2) determine the...

R. K. Stevens T. G. Dzubay C. W. Lewis R. W. Shaw

1983-01-01

65

An Intercomparison of Measurement Methods for Carbonaceous Aerosol in the Ambient Air in New York City  

Microsoft Academic Search

Measurement methods for fine carbonaceous aerosol were compared under field sampling conditions in Flushing, New York during the period of January and early February 2004. In-situ 5- to 60-minute average PM2.5 organic carbon (OC), elemental carbon (EC), and black carbon (BC) concentrations were obtained by the following methods: Sunset Laboratory field OC\\/EC analyzer, Rupprecht and Patashnick (R&P) series 5400 ambient

Prasanna Venkatachari; Liming Zhou; Philip K. Hopke; James J. Schwab; Kenneth L. Demerjian; Silke Weimer; Olga Hogrefe; Dirk Felton; Oliver Rattigan

2006-01-01

66

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

Microsoft Academic Search

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

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

2008-01-01

67

A method to quantify organic functional groups and inorganic compounds in ambient aerosols using attenuated total reflectance FTIR spectroscopy and multivariate chemometric techniques  

Microsoft Academic Search

An attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopic technique and a multivariate calibration method were developed to quantify ambient aerosol organic functional groups and inorganic compounds. These methods were applied to size-resolved particulate matter samples collected in winter and summer of 2004 at three sites: a downtown Phoenix, Arizona location, a rural site near Phoenix, and an urban fringe site

Charity Coury; Ann M. Dillner

2008-01-01

68

Technical Note: The application of an improved gas and aerosol collector for ambient air pollutants in China  

NASA Astrophysics Data System (ADS)

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 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. When applied in two major field campaigns (rural and coastal sites) in China, the GAC-IC system provided high-quality data in ambient conditions even under high loadings of pollutants. Its measurements were highly correlated with data by other commercial instruments such as the SO2 analyzer (43c, Thermo-Fisher, USA; R2 as 0.96), the HONO analyzer (LOPAP, Germany; R2 as 0.91 for samples from 15:00 to 07:00), a filter sampler (Tianhong, China; R2 as 0.86 for SO42-), and Aerosol Mass Spectrometer (AMS, Aerodyne, USA; R2 above 0.77 for major species) over a wide range of concentrations. Through the application of the GAC-IC system, it was identified that 70% of chloride and nitrate by the filter method could be lost during daytime sampling due to high temperature in the rural site of Kaiping. In Changdao field campaign (coastal site), though a particle dryer was applied, its drying efficiency was not well considered for the collection efficiency of AMS seemed still interfered a bit by local high relative humidity. If the inter-comparison was done with relative humidity below 50%, the correlations ranged from 0.81 to 0.94 for major species. Through laboratory and field studies, this instrument is proved particularly useful in future intensive campaigns or long-term monitoring stations to study various environmental issues such as secondary aerosol and haze formation, as well as climate change.

Dong, H.-B.; Zeng, L.-M.; Hu, M.; Wu, Y.-S.; Zhang, Y.-H.; Slanina, J.; Zheng, M.; Wang, Z.-F.; Jansen, R.

2012-11-01

69

Aerosol Interfaces Examined with Ambient Pressure Photoemission Spectroscopy  

NASA Astrophysics Data System (ADS)

Heterogeneous chemistry occurring at the liquid/vapor and solid/vapor interfaces plays a significant role in environmental and atmospheric chemistry. Despite the importance of understanding differences in chemical reactivity between surface and bulk solutions, there is a considerable lack of quantitative and chemically specific techniques that can operate under environmental and atmospherically relevant conditions. The significance of these interfacial types of measurements is becoming increasingly apparent. For example, recent studies have shown that ions can segregate to the surface in liquid salt solutions, changing the chemical reactivity of the liquid at its interface. Recent development of the ambient pressure photoelectron spectroscopy (APPES) facilitates chemical identification of molecules adsorbed onto liquid and solid surfaces at atmospherically relevant pressures. The specific advantage of this technique is that measurements can be made at pressures greater than 5 Torr, i.e. above the equilibrium vapor pressure of water at its triple point. Here, we describe the development of a novel synchrotron-based instrument that combines APPES with real-time droplet and nanoparticle surface analysis. Three experiments that address chemistry of model systems are presented: (a) the adsorption and chemical reaction of an atmospherically relevant polycyclic aromatic hydrocarbon (PAH) compound on model surfaces (b) a combined droplet train/APPES setup for the investigation of the liquid/vapor interface and (c) a particle flow reactor for the investigation of heterogeneous chemistry on liquid and solid nanoparticle surfaces. Initial results of the surface composition of methanol/water mixtures in the droplet train and oxidation of the PAH coronene by ozone on a model surface will be presented.

Mysak, E. R.; Starr, D. E.; Wilson, K. R.; Bluhm, H.

2007-12-01

70

Aerosol collection and analysis using diffuse reflectance infrared spectroscopy  

NASA Astrophysics Data System (ADS)

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.

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

71

Strong and weak acidity of aerosols collected over the northeastern United States  

SciTech Connect

Total sulfate, acidity, and principal cations were measured in aerosol samples collected from an aircraft over the northeastern United States and at ground level on filters protected by a denuder tube for NH/sub 3/. Aerosol acidity was determined by aqueous extraction of the filters and titration with NaOH. Strong and weak acid components were resolved by using Gran plots, and for 30 fall and summer samples the weak acidity comprised x +/- s = 26 +/- 12% of the total acidity. The strong acidity averaged 25 +/- 18% of the total sulfate equivalents. Hydrogen ion plus ammonium ion balanced closely the sulfate ion concentration with the ratio of equivalents of ((H/sup +/) + (NH/sub 4//sup +/))/(SO/sub 4//sup 2 -/) = 1.03 +/- 0.14 for 36 samples. A phase diagram for the H/sub 2/O-H/sub 2/SO/sub 4/-(HN/sub 4/)/sub 2/SO/sub 4/ system was used to determine that the aerosol particles were liquid at the ambient relative humidity in 24 of 47 cases. For the 24 liquid samples the calculated pH average 0.11 +/- 0.59.

Ferek, R.J.; Lazrus, A.L.; Haagenson, P.L.; Winchester, J.W.

1983-06-01

72

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

NASA Astrophysics Data System (ADS)

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 PM2.5 and PM10 (particulate matter with aerodynamic diameters less than 2.5 ?m and 10 ?m, 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), Ångström exponent of absorption (AEA), and Ångström 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, measured UV absorption coefficients were found to be much larger for biomass burning aerosol than for typical ambient aerosols.

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

2012-03-01

73

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

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. PMID:19452899

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

74

HOUSTON URBAN PLUME STUDY, 1974. MICROSCOPICAL IDENTIFICATION OF COLLECTED AEROSOLS  

EPA Science Inventory

An urban plume study was conducted in Houston during July 1974 to gain preliminary data on the concentration and composition of primary and secondary aerosols contributing to Houston's air pollution problem. Selected membrane filter samples containing urban aerosols were analyzed...

75

Characterization of ambient aerosol at a remote site and twin cities of Pakistan  

NASA Astrophysics Data System (ADS)

The pollution controls have significantly decreased pollutant concentrations in the industrialized nations in the west while the concentrations are expected to grow in developing countries. In this study the concentrations of major ions i.e SO4 2 -, NO3 -, NO2 -, Cl- , NH4 + and trace metals i.e. Al, V, Cr, Mn, Cu, As, Se, Cd, Sb, Ba, Ti and Pb were determined in aerosols at a remote site of Northern Pakistan in July 1996. Later in May 1998, a comparative study of aerosols in two size fractions (bulk &PM10) at 14 sites enabled to understand the anomalous distribution of several constituents present in the ambient air of the twin cities, Islamabad / Rawalpindi 90 km from South East of earlier site. The suspended particulate matter concentrations (bulk and PM10) were 475 ug/m3, 175 ug/m3 respectively. For urban areas Pb, Cd, Zn and Ni are obviously contributed by steel and other allied industries besides vehicle's contribution of lead and cadmium. In Northern area concentrations of Al, K, Ca, and Fe exceeded 1000 ng/m3. The SO2 concentrations varied from 0.03 to 1.2 ppb. Mean SO4 2- and NO3 - concentrations were 5.2 ug/m3 and 3.6 ug/m3 respectively. Concentrations of Se, Ti, Pb, Cd, Sb, Zn and As in all aerosol samples were highly enriched relative to average crustal abundances indicating significant anthropogenic contributions. As the dominant flow pattern from the Arabian Sea through India (monsoon air pattern) this may transport pollution derived aerosol and moisture from distant sources in China or India. Key word index: Aerosol, trace metals , enrichment, anions, air pollution, Islamabad/Rawalpindi, remote site.

Ghauri, B.; Lodhi, A.

76

Effects of SO2 oxidation on ambient aerosol growth in water and ethanol vapours  

NASA Astrophysics Data System (ADS)

Hygroscopicity (i.e. water vapour affinity) of atmospheric aerosol particles is one of the key factors in defining their impacts on climate. Condensation of sulphuric acid onto less hygroscopic particles is expected to increase their hygrocopicity and hence their cloud condensation nuclei formation potential. In this study, differences in the hygroscopic and ethanol uptake properties of ultrafine aerosol particles in the Arctic air masses with a different exposure to anthropogenic sulfur pollution were examined. The main discovery was that Aitken mode particles having been exposed to polluted air were more hygroscopic and less soluble to ethanol than after transport in clean air. This aging process was attributed to sulfur dioxide oxidation and subsequent condensation during the transport of these particle to our measurement site. The hygroscopicity of nucleation mode aerosol particles, on the other hand, was approximately the same in all the cases, being indicative of a relatively similar chemical composition despite the differences in air mass transport routes. These particles had also been produced closer to the observation site typically 3-8 h prior to sampling. Apparently, these particles did not have an opportunity to accumulate sulphuric acid on their way to the site, but instead their chemical composition (hygroscopicity and ethanol solubility) resembled that of particles produced in the local or semi-regional ambient conditions.

Petäjä, T.; Kerminen, V.-M.; Hämeri, K.; Vaattovaara, P.; Joutsensaari, J.; Junkermann, W.; Laaksonen, A.; Kulmala, M.

2004-11-01

77

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

SciTech Connect

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.

Bernd R.T. Simoneit; Xinhui Bi; Daniel R. Oros; Patricia M. Medeiros; Guoying Sheng; Jiamo Fu [Oregon State University, Corvallis, OR (United States). Environmental Sciences Program

2007-11-01

78

COLLECTION, CHEMICAL FRACTIONATION, AND MUTAGENICITY BIOASSAY OF AMBIENT AIR PARTICULATE  

EPA Science Inventory

The influence of industrialization and consequent increased concentration of urban particulate matter on the incidence of cancer has long been a concern. The first bioassays used to evaluate complex ambient air samples were whole-animal carcinogenesis bioassays. In these studies,...

79

Improved large-volume sampler for the collection of bacterial cells from aerosol.  

PubMed

A modified large-volume sampler was demonstrated to be an efficient device for the collection of mono-disperse aerosols of rhodamine B and poly-disperse aerosols of bacterial cells. Absolute efficiency for collection of rhodamine B varied from 100% with 5-mum particles to about 70% with 0.5-mum particles. The sampler concentrated the particles from 950 liters of air into a flow of between 1 and 2 ml of collecting fluid per min. Spores of Bacillus subtilis var. niger were collected at an efficiency of about 82% compared to the collection in the standard AGI-30 sampler. In the most desirable collecting fluids tested, aerosolized cells of Serratia marcescens, Escherichia coli, and Aerobacter aerogenes were collected at comparative efficiencies of approximately 90, 80, and 90%, respectively. The modified sampler has practical application in the study of aerosol transmission of respiratory pathogens. PMID:803820

White, L A; Hadley, D J; Davids, D E; Naylor, R

1975-03-01

80

Improved Large-Volume Sampler for the Collection of Bacterial Cells from Aerosol  

PubMed Central

A modified large-volume sampler was demonstrated to be an efficient device for the collection of mono-disperse aerosols of rhodamine B and poly-disperse aerosols of bacterial cells. Absolute efficiency for collection of rhodamine B varied from 100% with 5-?m particles to about 70% with 0.5-?m particles. The sampler concentrated the particles from 950 liters of air into a flow of between 1 and 2 ml of collecting fluid per min. Spores of Bacillus subtilis var. niger were collected at an efficiency of about 82% compared to the collection in the standard AGI-30 sampler. In the most desirable collecting fluids tested, aerosolized cells of Serratia marcescens, Escherichia coli, and Aerobacter aerogenes were collected at comparative efficiencies of approximately 90, 80, and 90%, respectively. The modified sampler has practical application in the study of aerosol transmission of respiratory pathogens. Images

White, L. A.; Hadley, D. J.; Davids, D. E.; Naylor, R.

1975-01-01

81

In-Situ ambient aerosol measurement over Los Angeles during CalNex2010 using a newly developed combined Thermal desorption Aerosol GC (TAG) and Aerodyne Aerosol Mass Spectromter (AMS) instrument: TAG-AMS  

NASA Astrophysics Data System (ADS)

We report the first results of ambient aerosol measurements over Pasadena during the California at the Nexus between Air Quality and Climate Change (CalNex) Experiment 2010 obtained with the newly developed TAG-AMS instrument. The TAG-AMS combines the advantages of the Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) (Canagaratna et al. 2007) measuring size distribution and mass loading for ambient aerosol and the Thermal desorption Aerosol Gas chromatograph (TAG) (Williams et al., 2006) instrument providing hourly measurements of speciated organic compounds. The gas chromatographically separated compounds from the TAG instrument are analyzed using the same electron impact ion source and HR-ToF-MS that is shared with the AMS measurement. The combination of hourly time resolved TAG measurements with the complimentary AMS measurements provides mass spectral analysis of the total organic aerosol (AMS) and a detailed molecular level analysis (TAG). We will present first results of in situ measurements of speciated organic aerosol composition and organic marker compounds of the aerosols observed at the Pasadena supersite. These results are used to define different source types contributing to the organic aerosols. This will provide further understanding of organic aerosol (OA) components such as hydrocarbon-like organic aerosol (HOA) and oxygenated organic aerosol (OOA) with which most of the OA at multiple measurement sites can be described. The TAG-AMS combined measurement obtained during CalNex2010 will provide more insight into source profiles and the identification of major local and regional sources of organic aerosol in an urban environment. Furthermore the results will be put into context with the measurements from standalone AMS and 2DTAG instruments which were simultaneously operated during the CalNex2010 experiment to verify the quality of the combined TAG-AMS instrument results.

Hohaus, T.; Lambe, A.; Williams, B. J.; Williams, L. R.; Kimmel, J.; Sueper, D.; Kreisberg, N. M.; Hering, S. V.; Isaacman, G. A.; Worton, D. R.; Goldstein, A.; Worsnop, D. R.; Jayne, J.

2010-12-01

82

Coated or Embedded? Organic Matter as a Host for Individual Ambient Atmospheric Aerosol Particles (Invited)  

NASA Astrophysics Data System (ADS)

Organic matter is a prominent form of atmospheric aerosol particle. It commonly occurs with soot, sulfate, metals, or mineral dust in individual, internally mixed particles and is important when estimating radiative and health effects of aerosols. The details of these mini-assemblages are well observed when using transmission electron microscopy (TEM). When organic matter hosts soot particles, it enhances the light absorption of the soot and thus its warming effects. We determined the shapes of organic matter embedding soot using electron tomography (ET) with a transmission electron microscope, calculated the radiative forcing of such particles, and compared them to those of various coating and mixing models. Organic matter in particles collected from the vicinity of Mexico City (as part of the MILAGRO - Megacity Initiative: Local and Global Research Observations - campaign conducted in March 2006) also hosts metal-bearing nanoparticles that can include Fe, Zn, Mn, Pb, Hg, Sn, Cr, Ni, Ti, V, or Ag as major constituents. Nanoparticles of Hg are especially abundant. The nanoparticles are interesting because of their small sizes and high surface-to-volume ratios, both of which make them highly reactive in the human body and can cause negative health effects. In these and samples from other areas, we commonly find organic matter coating or otherwise associated with (hosting) inorganic aerosol particles of all types. Although the atmospheric community commonly speaks of coatings onto aerosol particles, in the case of organic matter, a more apt term might be embedding rather than coating. Finally, such hosting by organic matter can influence the climate and health effects of aerosol particles.

Buseck, P. R.; Adachi, K.

2009-12-01

83

Development of a Static Sampler for the Measurement of Inhalable Aerosol in the Ambient Atmosphere (with Special Reference to PAHs).  

National Technical Information Service (NTIS)

The aim of the work described in the report was to develop a new static aerosol sampler for use in the environments around coking plants, to collect an appropriate fraction of aerosol in a form that can subsequently be assessed for polycyclic aromatic hyd...

D. Mark J. H. Vincent G. Lynch R. J. Aitken R. A. Botham

1990-01-01

84

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

SciTech Connect

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.

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

85

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

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

86

Levoglucosan enhancement in ambient aerosol during springtime transport events of biomass burning smoke to Southeast China  

NASA Astrophysics Data System (ADS)

An intensive field experiment was conducted at an urban and a rural site in Hong Kong to identify the influence of biomass burning emissions transported from distinct regions on ambient aerosol in coastal southeast China. Water-soluble ionic and carbonaceous species, specifically the biomass burning tracer levoglucosan, were analysed. Elevated levoglucosan concentrations with maxima of 91.5 and 133.7 ng m-3 and overall average concentrations of 30 and 36 ng m-3 were observed at the rural and urban sites, respectively. By combining the analysed meteorological data, backward trajectories, fire counts and Aerosol Index from the Earth Probe satellite, southwest China and the northern Philippines, together with the southeast China coast, were identified for the first time as source regions of the transported biomass burning particles at the surface level in rural Hong Kong. Occasional levoglucosan enhancements observed at urban Hong Kong were attributed to local incense and joss paper burning during the Ching-Ming festival period. The contributions of transported biomass burning emissions, especially from the northern Philippines, were estimated to account for 7.5% and 2.9% of OC and PM2.5, respectively.

Sang, Xue-Fang; Chan, Chuen-Yu; Engling, Guenter; Chan, Lo-Yin; Wang, Xue-Mei; Zhang, Yi-Nan; Shi, Si; Zhang, Zhi-Sheng; Zhang, Ting; Hu, Ming

2011-02-01

87

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

NASA Astrophysics Data System (ADS)

We present the first laboratory and ambient photoacoustic (PA) measurement of aerosol light absorption coefficients at ultraviolet (UV) 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. Exact T-matrix method calculations were used to model the absorption and scattering characteristics of fractal-like agglomerates of different compactness and varying number of monomers. With these calculations, we attempted to estimate the number of monomers and fractal dimension of laboratory generated kerosene soot. 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 PM2.5 and PM10 (particulate matter with aerodynamic diameters less than 2.5 ?m and 10 ?m, 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), Ångström exponent of absorption (AEA), and Ångström 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, measured UV absorption coefficients were found to be much larger for biomass burning aerosol than for typical ambient aerosols.

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

2011-09-01

88

Experimental study of the sampling artifact of chloride depletion from collected sea salt aerosols.  

PubMed

Sampling artifact of chloride depletion from collected sea salt particles was studied, based on simultaneous measurements of size distribution measurements by a 10-stage Micro-Orifice Uniform Deposit Impactor (MOUDI) and of PM2.5 measurements by a Compact Porous Metal Denuder Sampler (PMDS) at a coastal site in Hong Kong on May 7, 8, 9, 11, and 29, 1998. The ambient concentrations of SO2, HNO3, HNO2, and NH3 were also measured by the PMDS. PM2.5 measurements by the PMDS, which is equipped with denuders and nylon back filters, are compared with the PM1.8 and PM3.1 measurements by the MOUDI. The percentages of chloride depletion from sea salt aerosols in PM1.8 and PM3.1 were 4-45% higher than that in PM2.5. This suggests that chloride evaporation in PM1.8 and PM3.1 collected on Teflon filters of the MOUDI during sampling was present. From the sum of the contributions of particles on the Teflon and nylon filters of the PMDS, nitrate formation almost completely accounts for chloride depletion in PM2.5 prior to collection since the equivalent ratio of [Na+] to ([NO3-] + [Cl-]) is close to the seawater ratio of 0.85. However, it was found that 22-74% of nitrate and 45-86% of chloride in the collected particles on the Teflon filter of the PMDS evaporated during sampling. Excess chloride depletion unexplained by NO3- and nss-SO4(2-) was found in the collected particles on the Teflon filter of the PMDS. Similarly, an amount of 3.7-27.2 nequiv m-3 of excess depleted chloride (equivalent to 8-55% of total chloride depletion) was found in supermicron particles collected by the MOUDI. In the 1.8-3.1 microns particles, the excess depleted chloride is positively correlated to the chloride evaporated from the deposited particles. Particle--particle interactions are proposed to explain the evaporation of nitrates and chlorides in the PMDS and MOUDI measurements. The observed chloride depletion from seasalt aerosols was partially attributed to sampling artifact due to particle--particle interactions. PMID:11351735

Yao, X; Fang, M; Chan, C K

2001-02-01

89

CCN estimates from bulk hygroscopic growth factors of ambient aerosols during the pre-monsoon season over Central Nepal  

NASA Astrophysics Data System (ADS)

Aerosol size distribution (ambient and dried) and chemical composition were measured simultaneously using two Scanning Mobility Particle Sizers (SMPSs) and filters during the pre-monsoon season (April-June 2009) at two locations in Central Nepal: Dhulikhel, an urban site in the Kathmandu valley, and Besisahar, a rural village in the Marsyangdi valley. Diameter growth factors (DGF) were estimated using the larger mode (around 100 nm) of the aerosol size distributions. The measured DGF suggest that the aerosols were in metastable state below 80% RH owing to the strong diurnal cycle of relative humidity (RH) at Dhulikhel, while no discernible growth was observed for Besisahar. Assuming ideal behavior of water-soluble organic compounds and using their fraction as determined by water extraction of filters produced the best agreement for a two-component hygroscopic growth model with the observed DGFs. This finding together with the DGF and chemical composition data were used to determine the aerosol bulk hygroscopicity parameter, ?. The ? parameter suggests that aerosols in this region are less hygroscopic than aerosols reported in previous studies from other regions. The estimated ? and the vertically scaled aerosol size distribution were then used to estimate the CCN spectra. These are the first estimates of CCN spectra from ground-based observations for the Central Himalaya region.

Shrestha, Prabhakar; Barros, Ana P.; Khlystov, Andrei

2013-03-01

90

Evidence and quantitation of aromatic organosulfates in ambient aerosols in Lahore, Pakistan  

NASA Astrophysics Data System (ADS)

Organosulfates are important components of atmospheric organic aerosols, yet their structures, abundances, sources and formation processes are not adequately understood. This study presents the identification and quantitation of benzyl sulfate in atmospheric aerosols, which is the first confirmed atmospheric organosulfate with aromatic carbon backbone. Benzyl sulfate was identified and quantified in fine particulate matter (PM2.5) collected in Lahore, Pakistan, during 2007-2008. An authentic standard of benzyl sulfate was synthesized, standardized, and identified in atmospheric aerosols with quadrupole time-of-flight (Q-ToF) mass spectrometry (MS). Benzyl sulfate was quantified in aerosol samples using ultra performance liquid chromatography (UPLC) coupled to negative electrospray ionization triple quadrupole (TQ) MS. The highest benzyl sulfate concentrations were recorded in November and January 2007 (0.50 ± 0.11 ng m-3) whereas the lowest concentration was observed in July (0.05 ± 0.02 ng m-3). To evaluate matrix effects, benzyl sulfate concentrations were determined using external calibration and the method of standard addition; comparable concentrations were detected by the two methods, which ruled out significant matrix effects in benzyl sulfate quantitation. Three additional organosulfates with m/z 187, 201 and 215 were qualitatively identified as aromatic organosulfates with additional methyl substituents by high-resolution mass measurements and tandem MS. The observed aromatic organosulfates form a homologous series analogous to toluene, xylene, and trimethylbenzene, which are abundant anthropogenic volatile organic compounds (VOC), suggesting that aromatic organosulfates may be formed by secondary reactions. However, stronger statistical correlations of benzyl sulfate with combustion tracers (EC and levoglucosan) than with secondary tracers (SO42- and ?-pinene-derived nitrooxy organosulfates) suggest that aromatic organosulfates may be emitted from the combustion sources or their subsequent atmospheric processing. Further studies are needed to elucidate the sources and formation pathways of aromatic organosulfates in the atmosphere.

Kundu, S.; Quraishi, T. A.; Yu, G.; Suarez, C.; Keutsch, F. N.; Stone, E. A.

2013-05-01

91

Evidence and quantitation of aromatic organosulfates in ambient aerosols in Lahore, Pakistan  

NASA Astrophysics Data System (ADS)

Organosulfates are important components of atmospheric organic aerosols, yet their structures, abundances, sources and formation processes are not adequately understood. This study presents the identification and quantitation of benzyl sulfate in atmospheric aerosols, which is the first reported atmospheric organosulfate with aromatic carbon backbone. Benzyl sulfate was identified and quantified in fine particulate matter (PM2.5) collected in Lahore, Pakistan during 2007-2008. An authentic standard of benzyl sulfate was synthesized, standardized, and identified in atmospheric aerosols using ultra-performance liquid chromatography (UPLC) coupled with quadrupole time-of-flight (Q-ToF) mass spectrometry (MS). Benzyl sulfate was quantified in aerosol samples using UPLC coupled to negative electrospray ionization triple quadrupole (TQ) MS. The highest benzyl sulfate concentrations were recorded in November and January 2007 (0.50 ± 0.11 ng m-3) whereas the lowest concentration was observed in July (0.05 ± 0.02 ng m-3). To evaluate matrix effects, benzyl sulfate concentrations were determined using external calibration and the method of standard addition; comparable concentrations were detected by the two methods, which ruled out significant matrix effects in benzyl sulfate quantitation. Three additional organosulfates with m/z 187, 201 and 215 were qualitatively identified as aromatic organosulfates with additional methyl substituents by high-resolution mass measurements and tandem MS. The observed aromatic organosulfates form a homologous series analogous to toluene, xylene, and trimethylbenzene, which are abundant anthropogenic volatile organic compounds (VOC), suggesting that aromatic organosulfates may be formed by secondary reactions. Further studies are needed to elucidate the sources and formation pathways of aromatic organosulfates in the atmosphere.

Kundu, S.; Quraishi, T. A.; Yu, G.; Suarez, C.; Keutsch, F. N.; Stone, E. A.

2012-12-01

92

Geometric/aerodynamic equivalent diameter ratios of ash aggregate aerosols collected in burning Kuwaiti well fields  

NASA Astrophysics Data System (ADS)

The ratio of aerodynamic equivalent diameter to geometric diameter was found for aerosols collected at ground-level from burning oil fields in Kuwait. Ash and soil aerosols collected using an eight-stage DRUM impactor were geometrically sized by scanning electron microscopy. Ash aggregates are shown to have a geometric diameter over an order of magnitude larger than their aerodynamic value. Additionally, ash aggregates showed changes in both particle and aggregate morphology with aerodynamic size.

Reid, Jeffrey S.; Cahill, Thomas A.; Wakabayashi, Paul H.; Dunlap, Michael R.

93

Comparison of ambient aerosol extinction coefficients obtained from in-situ, MAX-DOAS and LIDAR measurements at Cabauw  

NASA Astrophysics Data System (ADS)

In the field, aerosol in-situ measurements are often performed under dry conditions (relative humidity RH<30-40%). Since ambient aerosol particles experience hygroscopic growth at enhanced RH, also their microphysical and optical properties - especially the aerosol light scattering - are strongly dependent on RH. The knowledge of this RH effect is of crucial importance for climate forcing calculations or for the comparison of remote sensing with in-situ measurements. Here, we will present results from a four-month campaign which took place in summer 2009 in Cabauw, The Netherlands. The aerosol scattering coefficient ?sp(?) was measured dry and at various, predefined RH conditions between 20 and 95% with a humidified nephelometer. The scattering enhancement factor f(RH,?) is the key parameter to describe the effect of RH on ?sp(?) and is defined as ?sp(RH,?) measured at a certain RH divided by the dry ?sp(dry,?). The measurement of f(RH,?) together with the dry absorption measurement (assumed not to change with RH) allows the determination of the actual extinction coefficient ?ep(RH,?) at ambient RH. In addition, a wide range of other aerosol properties were measured in parallel. The measurements were used to characterize the effects of RH on the aerosol optical properties. A closure study showed the consistency of the aerosol in-situ measurements. Due to the large variability of air mass origin (and thus aerosol composition) a simple parameterization of f(RH,?) could not be established. If f(RH,?) needs to be predicted, the chemical composition and size distribution needs to be known. Measurements of four MAX-DOAS (multi-axis differential optical absorption spectroscopy) instruments were used to retrieve vertical profiles of ?ep(?). The values of the lowest layer were compared to the in-situ values after conversion of the latter to ambient RH. The comparison showed a good correlation of R2=0.62-0.78, but the extinction coefficients were a factor of 1.5-3.4 larger than the in-situ values. Best agreement is achieved for a few cases characterized by low aerosol optical depths and low planetary boundary layer heights. Differences showed to be dependent on the applied MAX-DOAS retrieval algorithm. The comparison of the in-situ data to a Raman lidar (light detection and ranging) showed a good correlation and higher values measured by the lidar (R2=0.79, slope of 1.81) if the Raman retrieved profile was used to extrapolate the directly measured extinction coefficient to the ground. The comparison improved if only nighttime measurements were used in the comparison (R2=0.93, slope of 1.19).

Zieger, P.; Weingartner, E.; Henzing, J.; Moerman, M.; de Leeuw, G.; Mikkilä, J.; Ehn, M.; Petäjä, T.; Clémer, K.; van Roozendael, M.; Yilmaz, S.; Frieß, U.; Irie, H.; Wagner, T.; Shaiganfar, R.; Beirle, S.; Apituley, A.; Wilson, K.; Baltensperger, U.

2010-12-01

94

Real-time Characterization of Particle-bound Polycyclic Aromatic Hydrocarbons in Ambient Aerosols and From Motor-Vehicles Exhausts  

NASA Astrophysics Data System (ADS)

During the spring of 2007 a diffusion charger (DC), a photoelectric aerosol sensor (PAS), and a condensation particle counter (CPC) were operated a) in Wilmington (CA), an urban area near the Los Angeles port heavily influenced by a mix of industrial and gasoline- / diesel-fuelled vehicle emissions, and b) at the California Air Resource Board (CARB) Heavy-Duty Diesel Emissions Test Laboratory (HDETL), a dynamometer testing facility in downtown Los Angeles (CA). During the dynamometer tests, we characterized the exhausts of several individual types of vehicles, equipped with different emission control technologies, and operated under different driving conditions. Information about the chemical composition, active surface area, and particle number concentration from the PAS, DC, and CPC were combined to identify the main chemical and physical characteristics of the studied aerosols. In particular, the ratio between the PAS and the DC signals (PAS/DC) provided a reliable measurement of the amount of particle-bound Polycyclic Aromatic Hydrocarbon (pPAH) per unit area of the active surface of the particles. This quantity may be directly related to the amount of pPAHs transported into the human respiratory tract. Plots of the PAS/DC ratio versus the average surface particle diameter (Dp; estimated by combining DC and CPC measurements) were then used to distinguish between the presence/absence of nuclei mode particles and the presence/absence of an adsorbed layer on accumulation mode particles, for both ambient and dynamometer-tests data. All results were then complemented with measurements of the particle size distribution (SMPS) and of the black carbon (BC) aerosol content to obtain further insights on the pPAHs emitted by motor-vehicles and other sources. Integrated 24-h filter samples were also collected in Wilmington, solvent extracted and analyzed by GC/MS to determine the relative concentrations of the 11 most abundant pPAHs found at the urban site. Finally, these results were used to establish correlations between the concentrations of each individual PAH species and the measured PAS signal (from fA to ? g/m3).

Polidori, A.; Hu, S.; Biswas, S.; Sioutas, C.

2007-12-01

95

Modelling liquid saturation in filters collecting liquid aerosols  

Microsoft Academic Search

The removal of (oil) mists from air streams is important in many industrial applications, such as machining and cutting operations, engine closed crankcase ventilation, and compressed gas cleaning. Filters are by far the most efficient device for removing such particles, however, the filtration of liquid aerosol particles differs so greatly from dust filtration that it is almost a field in

N. Merkel; R. D Braddock; G. Kasper

2009-01-01

96

Examples of realistic aerosol particles collected in a cascade impactor  

Microsoft Academic Search

In this paper some scanning electron microscope photomicrographs showing examples of a variety of particulate aerosol shapes are presented. Compositions of particles also are presented. These particles represent samples from a number of different sources and locations including: solid propellant rocket motor plumes, active volcano plumes, the lower stratosphere over Sondrestrom, Greenland, and the upper troposphere over northern Texas. The

D. C. Woods

1980-01-01

97

Evaporation kinetics and phase of laboratory and ambient secondary organic aerosol  

PubMed Central

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 ?-pinene SOA and ambient atmospheric SOA. We found that even when gas phase organics are removed, it takes ?24 h for pure ?-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.

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

2011-01-01

98

A Morphometric and Compositional Approach to the Study of Ambient Aerosol in a Medium Industrial Town of Italy  

Microsoft Academic Search

Morphometric and compositional studies have been performed on both PM10–2.5 and PM2.5 aerosol collected in the city of Prato, Italy. Chemical analysis has been carried out using PIXE technique and factor analysis\\u000a was applied for the source apportionment process. Industrial emissions, vehicular traffic as well as crustal dust and marine\\u000a aerosol were the sources identified. SEM-EDS analysis has been employed

Giovanni Pratesi; Matteo Zoppi; Thomas Vaiani; Francesca Calastrini

2007-01-01

99

Evaluation of the applicability of the MOUDI impactor for aerosol collections with subsequent multielement analysis by PIXE  

NASA Astrophysics Data System (ADS)

The micro-orifice uniform deposit impactor (MOUDI) is an 8-stage impactor with cut-sizes down to 0.056 ?m and which allegedly provides uniform aerosol deposits for the various stages. In the present study it was examined how uniform the aerosol deposits really are for each impaction plate and whether the uniformity is sufficient for a straightforward PIXE analysis. This was done by collecting several samples of ambient aerosol with the MOUDI and by determining the deposition pattern of various elements on the foils through a linear PIXE scan across each impaction foil. It was found that the deposits are far from uniform at the millimeter level for the stage numbers up to 6. Despite this, concentration data can easily be obtained by PIXE from such samples, provided that the analyzed area is carefully selected and appropriate correction factors for the nonuniformity are employed. Some size distribution data are presented. A comparison is also made of the size distribution data and detection limits that result from employing the MOUDI in combination with PIXE with those obtainable by PIXE analysis of some other types of cascade impactors.

Maenhaut, W.; Ducastel, G.; Hillamo, R. E.; Pakkanen, T. A.

1993-04-01

100

Chemical characterization of the ambient organic aerosol soluble in water: 2. Isolation of acid, neutral, and basic fractions by modified size-exclusion chromatography  

Microsoft Academic Search

A method employing size-exclusion chromatography (SEC) with Total Organic Carbon detection is developed to isolate and quantify the water-soluble organic carbon (WSOC) component of ambient aerosol particles by acid, neutral, and basic functional groups. The method provides unique quantitative insights into the characteristics and possible sources of a large fraction of the organic aerosol. The SEC is combined with a

Amy P. Sullivan; Rodney J. Weber

2006-01-01

101

On the Evaporation Kinetics and Phase of Laboratory and Ambient Secondary Organic Aerosol  

NASA Astrophysics Data System (ADS)

Field measurements of secondary organic aerosol (SOA) find significantly higher mass loads than predicted by models, sparking intense effort that is focused on finding additional SOA sources, but leaves many of the fundamental assumptions that are used by models unchallenged. Current air-quality models use absorptive partitioning theory assuming SOA particles are liquid droplets that form 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 an 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 ?-pinene SOA and ambient atmospheric SOA. The experimental setup was first tested by measuring the evaporation kinetics of single component organic particles of known vapor pressure. We show that, as expected for liquid droplets, smaller particles evaporate faster, and that these data yield the correct vapor pressure. We then study the evaporation kinetics of ?-pinene SOA and find that evaporation proceeds in two stages: a fast stage, during which 50% of the particle volume evaporates in ~100 minutes, followed by a slower stage, when additional 25% evaporate in 1400 minutes, which is in sharp contrast to the ~10 minutes timescale predicted by current kinetic models. ?-pinene SOA formed in the presence of “spectator” hydrophobic organic vapors like dioctyl phthalate, dioctyl sebacate, pyrene, or their mixture, were shown to adsorb noticeable amounts of these organics, forming what we term here ‘coated’ SOA particles. We show that these adsorbed coatings reduce evaporation rates of SOA particles. Moreover, aging of coated SOA particles dramatically reduces evaporation rates, and in some cases nearly stops it. For example, aging of SOA with adsorbed pyrene reduces evaporation rate to the point that only ~11% of the particle volume evaporates within 24 hrs. For all cases studied in this work, SOA evaporation behavior is size-independent and does not follow the evaporation kinetics of liquid droplets, which is in sharp contrast with model assumptions. To address the question of how closely the laboratory observations described above reflect reality in the atmosphere we characterized the evaporation kinetics of size-selected atmospheric SOA particles sampled in-situ during the recent Carbonaceous Aerosols and Radiative Effects Study (CARES) field campaign. We find that the evaporation of ambient SOA is very similar to that of coated and aged laboratory-generated ?-pinene SOA. Ambient SOA particles in Sacramento, CA lose between 17% and 25% of their volume in 6 hours. Like laboratory SOA, their evaporation is size-independent and does not follow the kinetics of liquid droplets. The findings about SOA phase, evaporation rates, and the importance of spectator gases and aging - all indicate the need to reformulate the way SOA formation and evaporation are treated by models.

Zelenyuk, A.; Vaden, T.; Imre, D. G.; Beránek, J.; Shrivastava, M.

2010-12-01

102

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

NASA Astrophysics Data System (ADS)

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. ?13C values ranged from - 26.40‰ to - 25.10‰, with relative higher values in spring and summer, reflecting the increment of fossil carbon emissions.

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

2010-06-01

103

Laboratory Studies of Heterogeneous Reactions of HO2 Radical with Inorganic Aerosol Particles under the Ambient Conditions  

NASA Astrophysics Data System (ADS)

The HO2 uptake coefficient for aerosol particles ((NH4)2SO4 and NaCl) under ambient conditions (760Torr and 296K) was measured using an aerosol flow tube(AFT) coupled with a chemical conversion/laser-induced fluorescence(CC/LIF) technique. The CC/LIF technique enabled experiments to be performed at almost the same HO2 radical concentration as that in the atmosphere(~108 molecules cm-3). HO2 radicals were injected into the AFT through a vertically movable Pyrex tube. Injector position dependent profiles of LIF intensity were measured as a function of aerosol concentration at various relative humilities(RH). The uptake coefficients of dry aerosol (NaCl and (NH4)2SO4) particles were < 0.05, while the uptake coefficients of wet particles of NaCl and (NH4)2SO4 were estimated to be 0.10 and 0.15, respectively, which suggested that heterogeneous loss was enhanced by the particle containing water. To estimate the contribution of heterogeneous loss of HO2 by aerosol, the diurnal variation of HO2 using a box-model calculation was demonstrated. As a result, the daytime maximum concentrations of HO2 were changed to 95 and 70 %, relative to an absence of heterogeneous loss for marine and urban areas, respectively.

Taketani, F.; Kanaya, Y.; Akimoto, H.

2007-12-01

104

Improved Aerosol Collection by Combined Impaction and Centrifugal Motion  

Microsoft Academic Search

A new principle for collecting airborne particles, including microorganisms, has been introduced by injecting the particles into a swirling airflow from where they are removed onto a collection surface. A dry surface, a surface coated with an adhesive substance or a surface wetted by a liquid swirled onto the collection surface from a reservoir below can be used in the

Klaus willeke; Xuejun Lin; Sergey A. Grinshpun

1998-01-01

105

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

NASA Astrophysics Data System (ADS)

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 investigated WSOC sources over the northeastern U.S. and Canada. Two main sources were identified: biomass burning emissions from fires in the Alaska/Yukon region and emissions emanating from urban centers. Biomass burning WSOC was correlated with carbon monoxide (CO) and acetonitrile (R 2 > 0.88). Apart from the biomass burning influence, the highest concentrations were at low altitudes in distinct plumes of enhanced particle concentrations from urban centers. WSOC and CO were highly correlated (R2 > 0.78) in these urban plumes. The ratio of the enhancement in WSOC relative to that of CO was found to be low (˜ 3 microg C/m3/ppmv) in plumes that had been in transit for a short time, and increased with plume age, but appeared to level off at ˜32 microg C/m3/ppmv after approximately one day of transport from the sources. The results suggest WSOC in fine particles is produced from compounds co-emitted with CO and that these emissions are rapidly converted to organic particulate matter within ˜1 day following emission. To further chemically investigate the organic constituents of WSOC, a method for group speciation of the WSOC into hydrophilic and hydrophobic fractions has been developed using a XAD-8 resin column. XAD-8 resin coupled with a TOC analyzer allows for direct quantification. Based on laboratory calibrations with atmospherically relevant standards and 13C-NMR ( 13Carbon-Nuclear Magnetic Resonance) analysis, the hydrophilic fraction (compounds that penetrate the XAD-8 with near 100% efficiency at pH 2) is composed of short-chain carboxylic acids and carbonyls and saccharides. The fraction of WSOC retained by XAD-8, termed the hydrophobic fraction, includes aromatic acids, phenols, organic nitrates, cyclic acids, and carbonyls and mono-/dicarboxylic acids with greater than 3 or 4 carbons. Only aromatic compounds (or aromatic-like compounds with similar properties) can subsequently be extracted from XAD-8 with high efficiency and are referred to as the recovered hydrophobic fraction. By coupling a PILS with this technique, on-line measurements of WSO

Sullivan, Amy P.

106

Sampler for Collection and Analysis of Low Vapor Pressure Chemical (LVPC) Particulates/Aerosols.  

PubMed

Detection of low vapor pressure chemicals (LVPCs) such as pesticides and other toxic/hazardous materials on various environmental surfaces as well as LVPC aerosols is a significant challenge for current vapor phase detectors. We describe a novel sampling device which utilizes stainless steel screens coated with a sticky polydimethylsiloxane coating for collecting LVPCs aerosolized off of a surface. Results are presented for the collection and detection of a pesticide simulant, dimethyl methylphosphonate sorbed onto silica gel (DMMP/SG), using direct analysis in real time-cylindrical ion trap mass spectrometry (DART-CITMS). PMID:24053780

Ewing, K J; Gibson, D; Sanghera, J; Miklos, F

2013-10-03

107

Water-Aerosol Interactions Downwind of Mexico City: Inferences about Mixing State, Droplet Growth Kinetics and Aging of Ambient Aerosol  

NASA Astrophysics Data System (ADS)

We describe observations of size-resolved cloud droplet activation of partially aged Mexico City aerosol obtained during the MIRAGE campaign. These measurements provide unique insight into the integrated chemical properties and mixing state of the aerosol population, in addition to the water uptake kinetics of the particles as they grow into droplets, all of which are crucial constraints for understanding aerosol-cloud-climate interactions and chemical aging of polluted aerosol. A DMT Cloud Condensation Nucleus counter (CCNc) was operated in parallel to a particle counter with an upstream Differential Mobility Analyzer (DMA) to obtain the size-resolved activation fraction for a given water vapor supersaturation (SS). Activation spectra as a function of SS were obtained for the period of March 16-31, 2006. From the activation spectra, we determine the fraction of particles that act as CCN and the mean soluble mole fraction for these particles. We also estimate the variability in soluble mole fraction for these particles by analyzing the slope of the activation spectra, eliminating the effect of particle size variability inherent with the use of a DMA. We then perform "chemical closure" using the Aerosol Mass Spectrometer (AMS) dataset. The AMS data shows a large fraction of organic constituents, which may alter the cloud droplet growth kinetics. We monitor the droplet size distribution at the exit of the CCNc column, and, given the controlled conditions within the CCNc instrument, we can compare the observed droplet growth with the expected growth for classified, pure ammonium sulfate particles of the same critical supersaturation. A numerical model is used to parameterize the droplet growth kinetics in terms of a water vapor uptake coefficient.

Lance, S.; Padro, L.; Sullivan, A.; Weber, R.; Nenes, A.; Cross, E.; Onasch, T.; Worsnop, D.; Yu, X.; Alexander, L.; Smith, J. N.

2007-12-01

108

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...

109

Utilisation of Rep-PCR to track microbes in aerosols collected adjacent to their source, a saline lake in Victoria, Australia.  

PubMed

Dust storms are a major source of aerosolized bacteria, especially in the drought conditions experienced in Australia in the decade to 2009. The major aims of this project were to identify the culturable bacteria in environmental samples and to genetically fingerprint all isolates using repetitive element PCR (Rep-PCR) to investigate the possibility of tracking isolates from their source into the atmosphere. Four field trips were conducted to a dry lake in western Victoria, Australia to sample aerosols and sediments. Aerosols were collected at heights up to 150 m using vacuum pumps with filters attached to a tethered helium balloon, while corresponding sediments were collected in sterile polypropylene tubes. Isolates were cultivated on Tryptic Soy Agar, R2 Agar and Marine Agar, and grown in dark conditions at ambient temperature. By sequencing the 16S rRNA gene of 270 isolates, fifteen different bacterial families were identified, with both the aerosols and sediments dominated by the Bacillaceae family. Four sets of Rep-PCR primers were tested, with the ERIC and (GTG)5 primers proving to be the most suitable for fingerprinting the cultured taxa. Rep-PCR revealed very high strain diversity in the samples collected, however some strains were still able to be tracked from sediments up to 150 m in height. This shows the potential of Rep-PCR, however very large reference databases would be required for the technique to be more useful. PMID:23500831

Munday, Chris I; O'Loingsigh, Tadhg; Tapper, Nigel J; De Deckker, Patrick; Allison, Gwen E

2013-04-15

110

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

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 bisulfate, which is in turn consistent with the study average sulfate ammoniation corresponding to a molar ratio of NH4/SO4 of approximately one. The f(RH) curve for organics is not significantly different from one, suggesting that organics are weakly to nonhygroscopic. PMID:10842934

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

2000-05-01

111

Comparison of ambient aerosol extinction coefficients obtained from in-situ, MAX-DOAS and LIDAR measurements at Cabauw  

NASA Astrophysics Data System (ADS)

In the field, aerosol in-situ measurements are often performed under dry conditions (relative humidity RH<30-40%). Since ambient aerosol particles experience hygroscopic growth at enhanced RH, their microphysical and optical properties - especially the aerosol light scattering - are also strongly dependent on RH. The knowledge of this RH effect is of crucial importance for climate forcing calculations or for the comparison of remote sensing with in-situ measurements. Here, we will present results from a four-month campaign which took place in summer 2009 in Cabauw, The Netherlands. The aerosol scattering coefficient ?sp(?) was measured dry and at various, predefined RH conditions between 20 and 95% with a humidified nephelometer. The scattering enhancement factor f(RH,?) is the key parameter to describe the effect of RH on ?sp(?) and is defined as ?sp(RH,?) measured at a certain RH divided by the dry ?sp(dry,?). The measurement of f(RH,?) together with the dry absorption measurement (assumed not to change with RH) allows the determination of the actual extinction coefficient ?ep(RH,?) at ambient RH. In addition, a wide range of other aerosol properties were measured in parallel. The measurements were used to characterize the effects of RH on the aerosol optical properties. A closure study showed the consistency of the aerosol in-situ measurements. Due to the large variability of air mass origin (and thus aerosol composition) a simple parameterization of f(RH,?) could not be established. If f(RH,?) needs to be predicted, the chemical composition and size distribution need to be known. Measurements of four MAX-DOAS (multi-axis differential optical absorption spectroscopy) instruments were used to retrieve vertical profiles of ?ep(?). The values of the lowest layer were compared to the in-situ values after conversion of the latter ones to ambient RH. The comparison showed a good correlation of R2 = 0.62-0.78, but the extinction coefficients from MAX-DOAS were a factor of 1.5-3.4 larger than the in-situ values. Best agreement is achieved for a few cases characterized by low aerosol optical depths and low planetary boundary layer heights. Differences were shown to be dependent on the applied MAX-DOAS retrieval algorithm. The comparison of the in-situ extinction data to a Raman LIDAR (light detection and ranging) showed a good correlation and higher values measured by the LIDAR (R2 = 0.82-0.85, slope of 1.69-1.76) if the Raman retrieved profile was used to extrapolate the directly measured extinction coefficient to the ground. The comparison improved if only nighttime measurements were used in the comparison (R2 = 0.96, slope of 1.12).

Zieger, P.; Weingartner, E.; Henzing, J.; Moerman, M.; de Leeuw, G.; Mikkilä, J.; Ehn, M.; Petäjä, T.; Clémer, K.; van Roozendael, M.; Yilmaz, S.; Frieß, U.; Irie, H.; Wagner, T.; Shaiganfar, R.; Beirle, S.; Apituley, A.; Wilson, K.; Baltensperger, U.

2011-03-01

112

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

SciTech Connect

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.

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

2009-03-01

113

Efficient Collection of Atmospheric Aerosols with a Particle Concentrator—Electrostatic Precipitator Sampler  

Microsoft Academic Search

A novel particle sampling methodology developed recently by our group (Han et al. 2008) has been extended in this article to collect atmospheric particles in electrostatic precipitators (ESPs) for chemical and biological–toxicological analysis. Particles are grown to super-micron droplets via condensation of ultrapure deionized water, and concentrated by virtual impaction in the versatile aerosol concentration enrichment system (VACES). The grown

Bangwoo Han; Neelakshi Hudda; Zhi Ning; Yong-Jin Kim; Constantinos Sioutas

2009-01-01

114

Direct Collection of Aerosols by Electrostatic Classification for Size-Resolved Chemical Analysis  

Microsoft Academic Search

The performance of an inlet for the size-resolved collection of aerosols onto a heating filament for subsequent thermal desorption is presented. The device resembles a cylindrical Differential Mobility Analyzer (DMA) in that a sample flow is introduced around the periphery of the annulus between two concentric cylinders, and charged particles migrate inward towards the inner cylinder in the presence of

Denis J. Phares; Sonya Collier

2010-01-01

115

Thermophoresis and Its Thermal Parameters for Aerosol Collection  

SciTech Connect

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.

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

2007-08-01

116

THERMOPHORESIS AND ITS THERMAL PARAMETERS FOR AEROSOL COLLECTION  

SciTech Connect

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 25?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.

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

2007-01-01

117

Observation of ambient aerosol particle growth due to in-cloud processes within boundary layers  

NASA Astrophysics Data System (ADS)

Aerosol microphysical and optical properties were measured on board the CIRPAS Twin Otter aircraft during 16 flights at the Southern Great Plain (SGP) site in northern central Oklahoma as part of the Aerosol Intensive Operation period in May 2003. Within well-mixed boundary layers on four cloudy days, vertical profiles measured on board the Twin Otter show that dry aerosol size, volume concentration, and scattering coefficients all increased with increasing altitude, whereas the total number concentration remained essentially constant. A one-dimensional model, which uses simultaneous meteorological measurements as inputs, shows that the observed increase in aerosol volume concentration with increasing altitude is consistent with in-cloud sulfate production at the top of the boundary layer. The sulfate production rate was sufficiently fast to overcome the homogenization resulting from turbulent mixing. In contrast, on cloud-free days, measurements on a second aircraft show nearly uniform aerosol volume concentrations within well-mixed boundary layers. The observed vertical gradients in aerosol volume concentration suggest that even within well-mixed boundary layers, surface measurements may not be representative of aerosols properties (e.g., loading and scattering coefficients, etc.) at elevated altitudes, especially when SO2 concentration and cloud coverage are high.

Wang, Jian; Daum, Peter H.; Kleinman, Lawrence I.; Lee, Yin-Nan; Schwartz, Stephen E.; Springston, Stephen R.; Jonsson, Haflidi; Covert, David; Elleman, Robert

2007-07-01

118

Bubble characteristics and aerosol formation in electrowinning cells  

Microsoft Academic Search

The nature of the aerosol emitted from a scale model zinc electrowinning system, operated under industrial conditions, has been established as a function of bubble formation rate, electrode surface characteristics, coalescence of bubbles, and control strategies. The emitted aerosol was collected and characterized using an Andersen Ambient Impactor. The effect of the relative humidity of the ambient air on the

A. Papachristodoulou; F. R. Foulkes; J. W. Smith

1985-01-01

119

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

NASA Astrophysics Data System (ADS)

Organic aerosols are a ubiquitous component of the troposphere, from heavily polluted cities to the remote Arctic. In Chapters II, III, and V of this dissertation, the formation of organic aerosol through observations of ambient size distributions is addressed. Chapter IV presents a new pathway for the formation of nitrous acid (HONO) in the urban atmosphere. In Chapter II, the size-resolved chemical composition of sub-micron aerosol was measured at a suburban forested site in North Carolina. Two events were identified in which particle growth, presumably by gas-to-particle conversion, was dominated by accumulation of organic aerosol mass. Growth rates between 1.2 nm hr-1 and 4.9 nm hr-1 were observed. Using a mass-spectral deconvolution method coupled with linear regression analysis, the sub-micron organic aerosol mass observed during the campaign, and during events, was determined to have been influenced by both local and regional secondary processes with only a minor influence from combustion sources. In Chapter III, the chemical characteristics of sub-10-micron aerosol were explored as a function of ambient particle size at a coastal and inland site in New England. Average organic carbon (OC) concentrations of 4.9 microg C m-3 and 3.4 microg C m-3 were observed at the coastal site at the Isles of Shoals (IOS) and at the slightly inland site at Thompson Farm (TF), respectively. An average of 84 and 72% of OC was found to be water-soluble at IOS and TF, respectively. Size distributions indicate that the formation of dicarboxylic acids, especially oxalic acid, is driven by aqueous-phase reactions. A chemical fingerprint analysis suggests that all water-soluble OC at IOS resembles secondary organic aerosol (SOA), while WSOC at TF appears to result from mixed sources. In Chapter IV, a newly identified formation pathway for nitrous acid (HONO) is presented. HONO is an important precursor to hydroxyl radicals in the troposphere and thus contributes to the oxidative capacity of the atmosphere. The proposed pathway is shown to depend on the surface chemical characteristics of primary organic aerosol, and concentrations of HONO are shown to exceed those that can be explained by previously identified formation pathways. In Chapter V, particle growth events were observed at Summit, Greenland, an extremely remote Arctic site. Particle growth was linked indirectly to condensation of organic compounds because measured concentrations of sulfuric acid could not explain the observed growth rates of up to 0.963 nm hr -1. The snowpack may be the source of condensable organic precursors, and thus organic aerosol, based on prior observations at the site. This pathway represents a source of global SOA currently not taken into account that may have implications for climate regulation.

Ziemba, Luke D.

120

Direct and rapid determination of elements in the ambient air and in human exhalation using the electrostatic precipitation of aerosols in the graphite atomizer of a zeeman spectrometer  

Microsoft Academic Search

The use of a new Zeeman spectrometer with the electrostatic precipitation of aerosols in the graphite furnace of the atomizer\\u000a for the direct and rapid determination of aerosols in the ambient air and in the air exhaled by human beings is presented.\\u000a The results are given for the comparative determination of elements in laboratory air by electrostatic precipitation and with

A. A. Ganeev; N. B. Ivanenko; A. A. Ivanenko; M. A. Kuz’menkov; A. Skudra; M. N. Slyadnev; E. M. Yakovleva; E. B. Nosova

2006-01-01

121

Size-selective nonrefractory ambient aerosol measurements during the Particulate Matter Technology Assessment and Characterization Study-New York 2004 Winter Intensive in New York City  

Microsoft Academic Search

During the Particulate Matter Technology Assessment and Characterization Study-New York (PMTACS-NY) in January\\/February 2004 a variety of modern aerosol measurement instruments were deployed at a field site on the campus of Queens College in Queens, New York. These instruments included the Aerodyne Aerosol Mass Spectrometer (Q-AMS), R&P Particulate Ambient Sulfate and Nitrate monitors (8400S&N), a Particle-into-liquid Sampler equipped with ion

Silke Weimer; Frank Drewnick; Olga Hogrefe; James J. Schwab; Kevin Rhoads; Douglas Orsini; Manjula Canagaratna; Douglas R. Worsnop; Kenneth L. Demerjian

2006-01-01

122

Size-selective nonrefractory ambient aerosol measurements during the Particulate Matter Technology Assessment and Characterization Study–New York 2004 Winter Intensive in New York City  

Microsoft Academic Search

During the Particulate Matter Technology Assessment and Characterization Study–New York (PMTACS-NY) in January\\/February 2004 a variety of modern aerosol measurement instruments were deployed at a field site on the campus of Queens College in Queens, New York. These instruments included the Aerodyne Aerosol Mass Spectrometer (Q-AMS), R&P Particulate Ambient Sulfate and Nitrate monitors (8400S&N), a Particle-into-liquid Sampler equipped with ion

Silke Weimer; Frank Drewnick; Olga Hogrefe; James J. Schwab; Kevin Rhoads; Douglas Orsini; Manjula Canagaratna; Douglas R. Worsnop; Kenneth L. Demerjian

2006-01-01

123

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)

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 the MARGA units was evaluated by calculating the MARPD between the corresponding 1 hour concentrations from the two MARGA units, also with a performance goal of ? 40%. The MARGA units performed well for SO2, SO4-, NH3 and NH4+, with these compounds meeting the accuracy and precision goals. The MARGA units did not perform as well for HNO3 and NO3-, with both species linear regression slopes not achieving the accuracy target. Furthermore, for NO3-, the MARPD between both MARGA units and the reference filter pack was greater than 40%. Comparison of total nitrate (HNO3 + NO3-) suggests that the lesser performance of the MARGA units for these compounds likely results from aerosol volatility in the MARGA inlet/tubing or the reference filter pack and exchange of HNO3 with tubing walls. In addition, the NO3- concentrations were low (<0.5 ug m-3) for significant periods of the ETV assessment. Details of the comparison will be examined and suggested instrument improvements will be discussed.

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

124

Strategies for the simultaneous collection of vapours and aerosols with emphasis on isocyanate sampling.  

PubMed

Workplace air frequently contains hazardous substances that may be present as vapours or as aerosols with a wide range of particle sizes. Depending upon a chemical species' volatility and use, it may be present in significant amounts in both the vapour and particulate phases. Unfortunately, the mechanisms by which vapours and particles are removed from an air stream during pumped sampling are substantially different. Collection of vapour molecules relies on their diffusion to a surface during their residence time in a sampler. Once in contact with a surface, vapour molecules are trapped either by adsorption onto a solid surface, absorption by a liquid, or by reaction with the medium or chemicals in the medium. Aerosol particles are most frequently collected by filtration or inertial impaction. However, if it is necessary to collect both phases simultaneously, a sampler with two stages is generally required. The exact nature of the sampler depends upon the size of the aerosol particles and the physical and chemical characteristics of the species of interest. A number of recent projects undertaken by researchers at the National Institute for Occupational Safety and Health have dealt with development of sampling and analytical methods for compounds present in workplace air as both vapour and aerosol particles. One strategy invoked in several instances consisted of a filter for particle collection followed by an appropriate second stage for vapour collection. For organophosphorus pesticides, the second stage was a sorbent tube. For gaseous hydrogen fluoride, it was an alkaline-impregnated back-up pad. For formaldehyde, the second stage was an impinger containing an aqueous solution of sodium hydrogensulfite.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8154600

Streicher, R P; Kennedy, E R; Lorberau, C D

1994-01-01

125

Ambient air aerosols, total polycyclic aromatic hydrocarbons (PAHs) for day and night time in the traffic areas of Central Taiwan  

Microsoft Academic Search

Day and night time ambient air samples from a traffic intersection were collected using Noll Rotary Impactor (NRI) and micro?orifice uniform deposited impactor (MOUDI) samplers from June 1997 to August 1997 in central Taiwan to characterize the atmospheric particle mass, total Polycyclic aromatic hydrocarbons (PAHs) size distribution and total PAHs content for the day and night period in a traffic

1999-01-01

126

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

NASA Astrophysics Data System (ADS)

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.

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

2012-11-01

127

Occurrence and determination of organic pollutants in aerosol, precipitation, and sediment samples collected at Lake Balaton  

Microsoft Academic Search

The results of the determination of different organic pollutants [organic acids, polycyclic aromatic hydrocarbons (PAHs), n-alkanes, volatile hydrocarbons] in aerosols, precipitation, atmosphere, and sediment samples collected at Lake Balaton are presented. Different chromatographic methods were used: capillary zone electrophoresis (CZE) for organic acids, GC–MS for n-alkanes, solid-phase extraction (SPE) and HPLC for PAHs and thermal desorption–GC for BTEX (benzene, toluene,

Gyula Kiss; András Gelencsér; Zoltán Krivácsy; József Hlavay

1997-01-01

128

Chemical composition of ambient aerosol, ice residues and cloud droplet residues in mixed-phase clouds: single particle analysis during the Cloud and Aerosol Characterization Experiment (CLACE 6)  

NASA Astrophysics Data System (ADS)

Two different single particle mass spectrometers were operated in parallel at the Swiss High Alpine Research Station Jungfraujoch (JFJ, 3580 m a.s.l.) during the Cloud and Aerosol Characterization Experiment (CLACE 6) in February and March 2007. During mixed phase cloud events ice crystals from 5-20 ?m were separated from larger ice aggregates, non-activated, interstitial aerosol particles and supercooled droplets using an Ice-Counterflow Virtual Impactor (Ice-CVI). During one cloud period supercooled droplets were additionally sampled and analyzed by changing the Ice-CVI setup. The small ice particles and droplets were evaporated by injection into dry air inside the Ice-CVI. The resulting ice and droplet residues (IR and DR) were analyzed for size and composition by the two single particle mass spectrometers: a custom-built Single Particle Laser-Ablation Time-of-Flight Mass Spectrometer (SPLAT) and a commercial Aerosol Time-of-Flight Mass Spectrometer (ATOFMS, TSI Model 3800). During CLACE 6 the SPLAT instrument characterized 355 individual IR that produced a mass spectrum for at least one polarity and the ATOFMS measured 152 IR. The mass spectra were binned in classes, based on the combination of dominating substances, such as mineral dust, sulfate, potassium and elemental carbon or organic material. The derived chemical information from the ice residues is compared to the JFJ ambient aerosol that was sampled while the measurement station was out of clouds (several thousand particles analyzed by SPLAT and ATOFMS) and to the composition of the residues of supercooled cloud droplets (SPLAT: 162 cloud droplet residues analyzed, ATOFMS: 1094). The measurements showed that mineral dust was strongly enhanced in the ice particle residues. Close to all of the SPLAT spectra from ice residues did contain signatures from mineral compounds, albeit connected with varying amounts of soluble compounds. Similarly, close to all of the ATOFMS IR spectra show a mineral or metallic component. Pure sulfate and nitrate containing particles were depleted in the ice residues. Sulfate and nitrate was found to dominate the droplet residues (~90% of the particles). The results from the two different single particle mass spectrometers were generally in agreement. Differences in the results originate from several causes, such as the different wavelength of the desorption and ionisation lasers and different size-dependent particle detection efficiencies.

Kamphus, M.; Ettner-Mahl, M.; Klimach, T.; Drewnick, F.; Keller, L.; Cziczo, D. J.; Mertes, S.; Borrmann, S.; Curtius, J.

2010-08-01

129

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...

130

From molecular clusters to nanoparticles: Role of ambient ionization in tropospheric aerosol formation  

Microsoft Academic Search

We investigate the role of background ionization, associated mainly with galactic cosmic radiation, in the generation and evolution of ultrafine particles in the marine boundary layer. We follow the entire course of aerosol evolution, from the initial buildup of molecular clusters (charged and uncharged) through their growth into stable nanoparticles. The model used for this purpose is based on a

Fangqun Yu; Richard P. Turco

2001-01-01

131

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...

132

Investigating the Formation of Ambient Secondary Organic Aerosol in Southeastern USA  

Microsoft Academic Search

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,

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

2006-01-01

133

GROWTH LAWS FOR THE FORMATION OF SECONDARY AMBIENT AEROSOLS: IMPLICATIONS FOR CHEMICAL CONVERSION MECHANISMS  

EPA Science Inventory

The evolution of aerosol size distributions growing by gas-to-particle conversion has been observed recently in field and laboratory studies. A technique for extracting particle diameter growth rates from such data is presented. The functional dependence of these growth rates on ...

134

PASSIVE AEROSOL SAMPLER FOR CHARACTERIZATION, AMBIENT CONCENTRATION, AND PARTICLE SIZE MEASUREMENT  

EPA Science Inventory

This is an extended abstract of a presentation made at the Air and Waste Management Association's Symposium on Air Quality Measurement Methods and Technology, Durham, NC, May 9-11, 2006. The abstract describes the theory, design, and initial testing of a passive aerosol sampler f...

135

A study of the physical, chemical, and optical properties of ambient aerosol particles in Southeast Asia during hazy and nonhazy days  

Microsoft Academic Search

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

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

2006-01-01

136

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, ...

137

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

NASA Astrophysics Data System (ADS)

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 aerosols collected at CHAAMS was probably transported from the Asian continent.

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

138

Aerosols  

PubMed Central

We and others have recently reported that prions can be transmitted to mice via aerosols. These reports spurred a lively public discussion on the possible public-health threats represented by prion-containing aerosols. Here we offer our view on the context in which these findings should be placed. On the one hand, the fact that nebulized prions can transmit disease cannot be taken to signify that prions are airborne under natural circumstances. On the other hand, it appears important to underscore the fact that aerosols can originate very easily in a broad variety of experimental and natural environmental conditions. Aerosols are a virtually unavoidable consequence of the handling of fluids; complete prevention of the generation of aerosols is very difficult. While prions have never been found to be transmissible via aerosols under natural conditions, it appears prudent to strive to minimize exposure to potentially prion-infected aerosols whenever the latter may arise—for example in scientific and diagnostic laboratories handling brain matter, cerebrospinal fluids, and other potentially contaminated materials, as well as abattoirs. Equally important is that prion biosafety training be focused on the control of, and protection from, prion-infected aerosols.

2011-01-01

139

Inflammatory cytokine response to ambient particles varies due to field collection procedures.  

PubMed

In vitro assays of biological activity induced by particulate matter (PM) are a tool for investigating mechanisms of PM health effects. They have potential application to exposure assessment in chronic disease epidemiology. However, there has been little reporting of the impact of real-world PM collection techniques on assay results. Therefore, we examined the effect of sampling duration and postsampling delays in freezing on PM-induced biological activity. Duplicate samples of respirable ambient Los Angeles PM were collected on polyurethane foam filters during 17 days and during three contemporaneous consecutive shorter periods. After collection, one duplicate was stored at ambient temperature for 24 hours before freezing; the other was frozen immediately. Cytokine response (IL-1?, IL-6, IL-8, and TNF-?) to PM aqueous extract was assessed in THP-1 cells, a model for evaluating monocyte/macrophage lineage cell responses. There was consistent 3- to 4-fold variation in PM-induced cytokine levels across the three collection intervals. Compared with levels induced by PM pooled across the three periods, continuously collected PM-induced levels were reduced by 25% (IL-6) to 39% (IL-8). The pattern of cytokine gene expression response was similar. Cytokine level variation by time to freezing was not statistically significant. PM-induced inflammatory response varied substantially over a weekly time scale. We conclude that long PM sampling interval induced less activity than the average of equivalent shorter consecutive sampling intervals. Time to freezing was less important. Implications for development of metrics of long-term spatial variation in biological exposure metrics for study of chronic disease merit further investigation. PMID:23306836

McConnell, Rob; Wu, Weidong; Berhane, Kiros; Liu, Feifei; Verma, Gaurav; Peden, David; Diaz-Sanchez, David; Fruin, Scott

2013-04-01

140

Impact of Relative Humidity and Collection Media on Mycobacteriophage D29 Aerosol  

PubMed Central

This study was conducted to evaluate the effect of aerosol generation, methods of sampling, storage conditions, and relative humidity on the culturability of the mycobacteriophage D29. The lytic phage D29 can kill Mycobacterium tuberculosis, and the phage aerosol can be treated as a potential tool for tuberculosis treatment. The culturability of D29 was tested using a test chamber designed for the bioaerosols research against three spray liquids (deionized water, phosphate-buffered saline [PBS], and normal saline), four collection media (suspension medium [SM], nutrient broth, PBS, and deionized water), two sampling systems (the all-glass impinger AGI-30 and the Biosampler) and across a range of humidities (20 to 90%). The effect of storage conditions on the culturability of collected sample was also evaluated for the AGI-30 impinger. The results proved that viable phage D29 particles generated by deionized water were approximately 30- and 300-fold higher than PBS and normal saline, respectively. As collection media, SM buffer and nutrient broth were observed to yield a higher number of plaques compared to PBS and deionized water. No difference was observed in collection efficiency between AGI-30 and Biosampler with two detection methods (culture-based technique and real-time PCR). The culturability of collected D29 in SM buffer or nutrient broth can be maintained up to 12 h irrespective of storage temperature. Relative humidity was found to strongly influence airborne D29 culturability which is 2- to 20-fold higher in low humidity (25%) than medium (55%) or high (85%) humidity. This research will help identify the optimal means for the application of D29 aerosol in animal inhalation experiments.

Liu, Keyang; Wen, Zhanbo; Li, Na; Yang, Wenhui; Wang, Jie; Hu, Lingfei; Dong, Xiaokai; Lu, Jianchun

2012-01-01

141

Impact of relative humidity and collection media on mycobacteriophage D29 aerosol.  

PubMed

This study was conducted to evaluate the effect of aerosol generation, methods of sampling, storage conditions, and relative humidity on the culturability of the mycobacteriophage D29. The lytic phage D29 can kill Mycobacterium tuberculosis, and the phage aerosol can be treated as a potential tool for tuberculosis treatment. The culturability of D29 was tested using a test chamber designed for the bioaerosols research against three spray liquids (deionized water, phosphate-buffered saline [PBS], and normal saline), four collection media (suspension medium [SM], nutrient broth, PBS, and deionized water), two sampling systems (the all-glass impinger AGI-30 and the Biosampler) and across a range of humidities (20 to 90%). The effect of storage conditions on the culturability of collected sample was also evaluated for the AGI-30 impinger. The results proved that viable phage D29 particles generated by deionized water were approximately 30- and 300-fold higher than PBS and normal saline, respectively. As collection media, SM buffer and nutrient broth were observed to yield a higher number of plaques compared to PBS and deionized water. No difference was observed in collection efficiency between AGI-30 and Biosampler with two detection methods (culture-based technique and real-time PCR). The culturability of collected D29 in SM buffer or nutrient broth can be maintained up to 12 h irrespective of storage temperature. Relative humidity was found to strongly influence airborne D29 culturability which is 2- to 20-fold higher in low humidity (25%) than medium (55%) or high (85%) humidity. This research will help identify the optimal means for the application of D29 aerosol in animal inhalation experiments. PMID:22194291

Liu, Keyang; Wen, Zhanbo; Li, Na; Yang, Wenhui; Wang, Jie; Hu, Lingfei; Dong, Xiaokai; Lu, Jianchun; Li, Jinsong

2011-12-22

142

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

Federal Register 2010, 2011, 2012, 2013

...Comment Request; Ambient Air Quality Surveillance (Renewal) AGENCY: Environmental...request (ICR), Ambient Air Quality Surveillance (Renewal) (EPA ICR No. 0940.27...associated with the Ambient Air Quality Surveillance Rule, 40 CFR part 58. This data...

2013-09-19

143

Comparison of ambient aerosol extinction coefficients obtained from in-situ, MAX-DOAS and LIDAR measurements at a continental site (Cabauw)  

NASA Astrophysics Data System (ADS)

In the field, aerosol in-situ measurements are often performed under dry conditions (relative humidity RH<30-40%). Since ambient aerosol particles experience hygroscopic growth at enhanced RH, their microphysical and optical properties - especially the aerosol light scattering - are strongly dependent on RH. The knowledge of this RH effect is of eminent importance for climate forcing calculations or for the comparison of remote sensing with in-situ measurements. We will present results from a four-month campaign which took place in summer 2009 in Cabauw (Netherlands) and was part of the Cabauw Intercomparison Campaign of Nitrogen Dioxide measuring Instruments (CINDI). During this campaign different remote sensing and in-situ instruments were used to derive atmospheric gas species and aerosol properties. The aerosol scattering coefficient ?sp(?) was measured dry and at various, predefined RH conditions between 20 and 95% with a recently developed humidified nephelometer (WetNeph). The scattering enhancement factor f(RH,?) is the key parameter to describe the effect of RH on ?sp(?) and is defined as ?sp(?,RH) measured at a certain RH divided by the dry ?sp(?,RH=dry). The measurement of f(RH) together with the dry absorption measurement allows the determination of the actual extinction coefficient ?ep(?) at ambient RH. In addition, a wide range of further aerosol properties were measured in parallel. The measurements were used to characterize the effects of RH on the aerosol optical properties. A closure study showed the consistency of the aerosol in-situ measurements. Due to the large variability of airmass origin and aerosol composition a simple categorization could not be established. If f(RH) needs to be predicted, the chemical composition needs to be known. Four MAX-DOAS (multi-axis differential optical absorption spectroscopy) instruments retrieved vertical profiles of ?ep(?). The aerosol extinction corresponding to the lowest profile layer can be directly compared to the in-situ values, which were re-calculated to ambient RH. The comparison showed a good correlation of R2=0.59-0.78, but a factor of 1.4-2.76 higher extinction coefficients compared to the in-situ measured values. Best agreement is achieved for a few cases characterized by low aerosol optical depths and low planetary boundary layer heights. Differences showed to be dependent on the applied MAX-DOAS retrieval algorithm. The comparison of the in-situ data to a Raman lidar (light detection and ranging) showed much better agreement if the Raman retrieved profile was used to extrapolate the directly measured extinction coefficient to ground.

Zieger, P.; Weingartner, E.; Henzing, B.; Moerman, M.; de Leeuw, G.; Mikkilä, J.; Clémer, K.; van Roozendael, M.; Yilmaz, S.; Friess, U.; Irie, H.; Wagner, T.; Shaiganfar, R.; Beirle, S.; Apituley, A.; Wilson, K.; Baltensperger, U.

2010-12-01

144

High-resolution electrospray ionization mass spectrometry analysis of water-soluble organic aerosols collected with a particle into liquid sampler.  

PubMed

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 m(3) 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 abundances, 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 the 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. PMID:20809606

Bateman, Adam P; Nizkorodov, Sergey A; Laskin, Julia; Laskin, Alexander

2010-10-01

145

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 ...

146

Characterization of aerosol scattering and spectral absorption by unique methods: a polar/imaging nephelometer and spectral reflectance measurements of aerosol samples collected on filters  

NASA Astrophysics Data System (ADS)

Characterization of aerosol scattering and absorption properties is essential to accurate radiative transfer calculations in the atmosphere. Applications of this work include remote sensing of aerosols, corrections for aerosol distortions in satellite imagery of the surface, global climate models, and atmospheric beam propagation. Here we demonstrate successful instrument development at the Laboratory for Aerosols, Clouds and Optics at UMBC that better characterizes aerosol scattering phase matrix using an imaging polar nephelometer (LACO-I-Neph) and enables measurement of spectral aerosol absorption from 200 nm to 2500 nm. The LACO-I-Neph measures the scattering phase function from 1.5° to 178.5° scattering angle with sufficient sensitivity to match theoretical expectations of Rayleigh scattering of various gases. Previous measurements either lack a sufficiently wide range of measured scattering angles or their sensitivity is too low and therefore the required sample amount is prohibitively high for in situ measurements. The LACO-I-Neph also returns expected characterization of the linear polarization signal of Rayleigh scattering. Previous work demonstrated the ability of measuring spectral absorption of aerosol particles using a reflectance technique characterization of aerosol samples collected on Nuclepore filters. This first generation methodology yielded absorption measurements from 350 nm to 2500 nm. Here we demonstrate the possibility of extending this wavelength range into the deep UV, to 200 nm. This extended UV region holds much promise in identifying and characterizing aerosol types and species. The second generation, deep UV, procedure requires careful choice of filter substrates. Here the choice of substrates is explored and preliminary results are provided.

Dolgos, Gergely; Martins, J. Vanderlei; Remer, Lorraine A.; Correia, Alexandre L.; Tabacniks, Manfredo; Lima, Adriana R.

2010-02-01

147

Single Particle Scanning Electron Microscopy Analysis of Wet-Season Aerosol Collected in the Amazonian Tropical Rain Forest (Manaus, Brasil)  

NASA Astrophysics Data System (ADS)

Single particle analysis of aerosols particles larger than 0.2 ?m diameter was performed on samples collected in the tropical rain forest (Manaus, Brasil) during the AMAZE campaign in February and March 2008. The elemental composition and morphology of the particles were determined using SEM-EDX. The aerosol particles were divided into 10 groups according to their chemical composition and morphology: droplets of organic aerosol (OA), primary biogenic particles with and without OA coatings, other carbonaceous aerosol with and without OA coatings, mineral dust with and without OA coating and sea salt with and without OA coatings were identified as the most abundant aerosol groups. We present size distributions for all particle groups and the abundance of these groups in different size ranges. Due to careful investigation of the samples at a low acceleration voltage for the first time OA droplets and coatings were identified as a significant contribution to wet season aerosol mass collected in the Amazonian tropical rain forest, during single particle SEM analysis. During days with low aerosol loadings, OA droplets typically accounted for >50% of the accumulation mode aerosol, OA droplets with sea salt core (20- 40%), other carbonaceous aerosol (5-10%), mineral dust (5-10%), and primary biogenic particles with and without OA coatings accounted for most of the remainder. Coarse mode particles were dominated by primary biogenic particles with (>50%) and without (~10-20%) OA coatings. Mineral dust (~10- 20%), sea salt (~10%), dust with OA coatings (~10%) and OA droplets (~5%) accounted for most of the remainder. During days with higher particle numbers the relative abundance of other carbonaceous aerosol with (~20%) and without (~10%) OA coatings increased. The high frequency of OA coatings on different particles types has implications for the radiative properties as well as the hygroscopic behavior of wet season aerosol particles. For the first time we investigate the frequency of such coatings on different particle types and for different size ranges.

Sinha, B. W.; Huth, J.; Hoppe, P.; Borrmann, S.

2008-12-01

148

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

NASA Astrophysics Data System (ADS)

Particulate matter having an aerodynamic diameter less than 2.5 ?m (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.

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

149

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

NASA Astrophysics Data System (ADS)

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-containing boundary layer. Sea salt-cored aggregates could form when ash particles travel over a maritime environment and sea salt aerosol could easily be incorporated in the plume from the surrounding atmosphere. When the particles are sampled, pressure drops within the DRUM impactor cause the water in the droplet to evaporate, leaving behind ash aggregated with salt

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

2010-12-01

150

Ambient ammonia and ammonium aerosol across a region of variable ammonia emission density  

Microsoft Academic Search

We present 1 year of ambient ammonia (NH3), ammonium (NH4+), hydrochloric acid (HCl), chloride (Cl?), nitric acid (HNO3), nitrate (NO3?), nitrous acid (HONO), sulfur dioxide (SO2), and sulfate (SO42?) concentrations at three sites in the Coastal Plain region of North Carolina. The three sites, Clinton, Kinston, and Morehead City, are located in counties with total NH3 emission densities of 4800,

J. T. Walker; Dave R Whitall; Wayne Robarge; Hans W. Paerl

2004-01-01

151

Evaporation Kinetics and Phase of Laboratory and Ambient Secondary Organic Aerosol  

SciTech Connect

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.

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

2011-02-08

152

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

Microsoft Academic Search

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

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

2004-01-01

153

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

Microsoft Academic Search

Radiocarbon (14C) and stable carbon isotope ratios (?13C) 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 ?13C of individual n-fatty acids in an aerosol sample collected from northern Japan in spring 2001 during

Kimitaka Kawamura; Kohei Matsumoto; Masao Uchida; Yasuyuki Shibata

2010-01-01

154

Aerosolization of fungi, (1?3)-?- d glucan, and endotoxin from flood-affected materials collected in New Orleans homes  

Microsoft Academic Search

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)-?-d glucan, and endotoxin from eight flood-affected floor and bedding materials collected in New Orleans homes, following Hurricane Katrina. Aerosolization was examined using

Atin Adhikari; Jaehee Jung; Tiina Reponen; Jocelyn Suzanne Lewis; Enjoli C. DeGrasse; L. Faye Grimsley; Ginger L. Chew; Sergey A. Grinshpun

2009-01-01

155

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

Microsoft Academic Search

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

Lucinda Spokes; Timothy Jickells

1995-01-01

156

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 ...

157

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 ...

158

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...

159

Source estimation of anthropogenic aerosols collected by a DRUM sampler during spring of 2002 at Gosan, Korea  

NASA Astrophysics Data System (ADS)

Continuous measurements of trace elements in size-segregated aerosols were performed by X-ray fluorescence analysis in order to assess the transport of natural and anthropogenic aerosol sources to Gosan site in springtime 2002. Various aerosol elemental components (such as Al, Ca, Si, K, Ti, and Mn) had low enrichment factors close to one and exhibited a similar temporal variation in coarse particle range (2.5-12 ?m) indicating the dominant influence of soil dust. On the other hand, in the fine particle size range (0.09-2.5 ?m), several anthropogenic elements in ambient particles (such as As, Se, Zn, Pb, and Cu) revealed high enrichment (100aerosol composition data in order to identify anthropogenic sources of aerosols during non-Asian dust (NAD) period. As a result, it was found that the coarse particles were mainly influenced by soil, seasalt, coal combustion, and metallurgical emission and fine particles were significantly attributed to several anthropogenic sources, such as oil combustion, nonferrous metal source, and municipal incineration. Especially, submicron particles (0.09-0.56 ?m) were further impacted by motor vehicles and field burning emissions in addition to those sources.

Han, J. S.; Moon, K. J.; Ryu, S. Y.; Kim, Y. J.; Perry, Kevin D.

160

Local emission of primary air pollutants and its contribution to wet deposition and concentrations of aerosols and gases in ambient air in Japan  

NASA Astrophysics Data System (ADS)

We studied wet deposition by precipitation and the concentrations of aerosols and gases in ambient air in relation to the primary air pollutants discharged from domestic areas. The concentrations of aerosols and gases were influenced by nearby emissions except for non-sea-salt SO, which is transported long distances. The area facing the Sea of Japan showed much larger wet deposition than other areas, although the domestic emissions of the primary air pollutants there were small and showed a peak in wet deposition from October to March, as distinct from April to September in other areas. We performed the correlation analyses between wet deposition of each component and the product of the concentrations of corresponding aerosols and gases in ambient air and the two-thirds power of the precipitation. From the results, following scavenging processes were suggested. • Sulfate and ammonium were scavenged in precipitation as particulate matter such as (NH4)2SO4 and NH4HSO4. • Nitrate was scavenged mainly in precipitation through gaseous HNO3. • Ammonium was complementarily scavenged in precipitation through aerosols such as (NH4)2SO4 and NH4HSO4 and through gaseous NH3.

Aikawa, Masahide; Hiraki, Takatoshi; Tomoyose, Nobutaka; Ohizumi, Tsuyoshi; Noguchi, Izumi; Murano, Kentaro; Mukai, Hitoshi

2013-11-01

161

Elemental and iron isotopic composition of aerosols collected in a parking structure.  

PubMed

The trace metal contents and iron isotope composition of size-resolved aerosols were determined in a parking structure in Tempe, AZ, USA. Particulate matter (PM)<2.5 microm in diameter (the fine fraction) and PM>2.5 microm were collected. Several air toxics (e.g., arsenic, cadmium, and antimony) were enriched above the crustal average, implicating automobiles as an important source. Extremely high levels of fine copper (up to 1000 ng m(-3)) were also observed in the parking garage, likely from brake wear. The iron isotope composition of the aerosols were found to be +0.15+/-0.03 per thousand and +0.18+/-0.03 per thousand for the PM<2.5 microm and PM>2.5 microm fractions, respectively. The similarity of isotope composition indicates a common source for each size fraction. To better understand the source of iron in the parking garage, the elemental composition in four brake pads (two semi-metallic and two ceramic), two tire tread samples, and two waste oil samples were determined. Striking differences in the metallic and ceramic brake pads were observed. The ceramic brake pads contained 10-20% copper by mass, while the metallic brake pads contained about 70% iron, with very little copper. Both waste oil samples contained significant amounts of calcium, phosphorous, and zinc, consistent with the composition of some engine oil additives. Differences in iron isotope composition were observed between the source materials; most notably between the tire tread (average=+0.02 per thousand) and the ceramic brake linings (average=+0.65 per thousand). Differences in isotopic composition were also observed between the metallic (average=+0.18 per thousand) and ceramic brake pads, implying that iron isotope composition may be used to resolve these sources. The iron isotope composition of the metallic brake pads was found to be identical to the aerosols, implying that brake dust is the dominant source of iron in a parking garage. PMID:19540567

Majestic, Brian J; Anbar, Ariel D; Herckes, Pierre

2009-06-21

162

Characterization of ambient aerosol from measurements of cloud condensation nuclei during the 2003 Atmospheric Radiation Measurement Aerosol Intensive Observational Period at the Southern Great Plains site in Oklahoma  

Microsoft Academic Search

Measurements were made by a new cloud condensation nuclei (CCN) instrument (CCNC3) during the Atmospheric Radiation Measurement (ARM) Program's Aerosol Intensive Observational Period (IOP) in May 2003 in Lamont, Oklahoma. An inverse aerosol\\/CCN closure study is undertaken, in which the predicted number concentration of particles available for activation (NP) at the CCNC3 operating supersaturations is compared to that observed (NO).

T. A. Rissman; T. M. VanReken; J. Wang; R. Gasparini; D. R. Collins; H. H. Jonsson; F. J. Brechtel; R. C. Flagan; J. H. Seinfeld

2006-01-01

163

OM/OC Ratio and Specific Attenuation Coefficient in Ambient Particulate Matter at a Rural Site in Southern Ontario: Implications for Aerosol Aging and Emission Sources  

NASA Astrophysics Data System (ADS)

Carbonaceous species (organic carbon (OC) and elemental carbon (EC)) contribute a large portion of atmospheric fine particle mass and influence air quality, human health, and climate forcing. However, their emission sources and atmospheric aging processes are not well understood. The OM/OC ratio, defined as the organic mass per unit OC mass, is useful to understand the degree of oxidation of aerosol particles in atmospheric processes. We define the modified BC/EC (mod BC/EC) ratio as the ratio of the non-scattering corrected absorption coefficient per unit mass of EC. The mod BC/EC ratio has a similar meaning as the site specific attenuation coefficient, which is an important parameter used to convert light absorption measurements to black carbon mass. The mod BC/EC ratio can vary due to light scattering effect on absorption measurements, in which the oxygenated organics may play a role. The pyrolysis organic carbon (POC) is defined as the carbon mass fraction obtained at T= 870°C under a pure helium environment using the thermal separation method [Huang et al., 2006]. Since POC mass is generally proportional to the amount of oxygenated OC, studying the relationships among OC, EC, POC, as well as OM/OC and mod BC/EC ratios may help us understand the mechanisms of aerosol aging from different emission sources. Two 1-month field studies were conducted at a rural site in southern Ontario (NW of Toronto) during fall 2005 and spring 2007. Quartz filter samples were collected and analyzed for OC, POC, and EC concentrations using a thermal/optical method [Huang et al., 2006]. Together with the total organic matter measured by an Aerodyne Aerosol Mass Spectrometer (AMS) and the absorption coefficient obtained from a Particle Soot Absorption Photometer (PSAP), the OM/OC and mod BC/EC ratios for ambient aerosols were obtained. Our results show that when air mass was mainly from south, OC, POC, and EC were relatively high, with average ratios of OC/EC, OM/OC, and POC/EC as 1.94, 1.41, and 0.52, respectively; this indicates significant anthropogenic impacts and relatively large portion of oxygenated OC, which might be due to either primary emissions or photo-chemical reactions occurred in a short period of time. When air mass was mainly from north, OC, POC, and EC were much lower, with average ratios of OC/EC, OM/OC, and POC/EC as 3.10, 1.20, and 0.79, respectively; this suggests less influence from anthropogenic emissions and relatively aged air mass from biogenic-source dominated clean air. Using POC, we estimate the specific attenuation at the site to be 5.8 m2 g-1 independent of the air mass origin. The relationships among OM/OC, mod BC/EC, and POC will be further discussed. References: Huang, L., Brook, J.R., Zhang, W., Li, S.M., Graham, L., Ernst, D., Chivulescu, A., and Lu, G. (2006) Stable isotope measurements of carbon fractions (OC/EC) in airborne particulate: a new dimension for source characterization and apportionment, Atmospheric Environment, 40, 2690-2705.

Chan, T. W.; Huang, L.; Leaitch, R.; Sharma, S.; Brook, J.; Slowik, J.; Abbatt, J.

2008-05-01

164

Spectral light absorption by ambient aerosols influenced by biomass burning in the Amazon Basin. I: Comparison and field calibration of absorption measurement techniques  

NASA Astrophysics Data System (ADS)

Spectral aerosol light absorption is an important parameter for the assessment of the radiation budget of the atmosphere. Although on-line measurement techniques for aerosol light absorption, such as the Aethalometer and the Particle Soot Absorption Photometer (PSAP), have been available for two decades, they are limited in accuracy and spectral resolution because of the need to deposit the aerosol on a filter substrate before measurement. Recently, a 7-wavelength (?) Aethalometer became commercially available, which covers the visible (VIS) to near-infrared (NIR) spectral range (?=450-950 nm), and laboratory calibration studies improved the degree of confidence in these measurement techniques. However, the applicability of the laboratory calibration factors to ambient conditions has not been investigated thoroughly yet. As part of the LBA-SMOCC (Large scale Biosphere atmosphere experiment in Amazonia - SMOke aerosols, Clouds, rainfall and Climate) campaign from September to November 2002 in the Amazon basin we performed an extensive field calibration of a 1-? PSAP and a 7-? Aethalometer utilizing a photoacoustic spectrometer (PAS, 532 nm) as reference device. Especially during the dry period of the campaign, the aerosol population was dominated by pyrogenic emissions. The most pronounced artifact of integrating-plate type attenuation techniques (e.g. Aethalometer, PSAP) is due to multiple scattering effects within the filter matrix. For the PSAP, we essentially confirmed the laboratory calibration factor by Bond et al. (1999). On the other hand, for the Aethalometer we found a multiple scattering enhancement of 5.23 (or 4.55, if corrected for aerosol scattering), which is significantly larger than the factors previously reported (~2) for laboratory calibrations. While the exact reason for this discrepancy is unknown, the available data from the present and previous studies suggest aerosol mixing (internal versus external) as a likely cause. For Amazonian aerosol, we found no absorption enhancement due to hygroscopic particle growth in the relative humidity (RH) range between 40% and 80%. However, a substantial bias in PSAP sensitivity that correlated with both RH and temperature (T) was observed for 20%ambient sampling based on the data from the present and previous studies. For this study, the estimated accuracies of the absorption coefficients determined by the PAS, PSAP and Aethalometer were 10, 15 and 20% (95% confidence level), respectively.

Schmid, O.; Artaxo, P.; Arnott, W. P.; Chand, D.; Gatti, L. V.; Frank, G. P.; Hoffer, A.; Schnaiter, M.; Andreae, M. O.

2006-08-01

165

Spectral light absorption by ambient aerosols influenced by biomass burning in the Amazon Basin I. Comparison and field calibration of absorption measurement techniques  

NASA Astrophysics Data System (ADS)

Spectral aerosol light absorption is an important parameter for the assessment of the radiation budget of the atmosphere. Although on-line measurement techniques for aerosol light absorption, such as the Aethalometer and the Particle Soot Absorption Photometer (PSAP), have been available for two decades, they are limited in accuracy and spectral resolution because of the need to deposit the aerosol on a filter substrate before measurement. Recently, a 7-wavelength (?) Aethalometer became commercially available, which covers the visible (VIS) to near-infrared (NIR) spectral range (?=450-950 nm), and laboratory calibration studies improved the degree of confidence in these measurement techniques. However, the applicability of the laboratory calibration factors to ambient conditions has not been investigated thoroughly yet. As part of the LBA-SMOCC (Large scale Biosphere atmosphere experiment in Amazonia - SMOke aerosols, Clouds, rainfall and Climate) campaign from September to November 2002 in the Amazon basin we performed an extensive field calibration of a 1-? PSAP and a 7-? Aethalometer utilizing a photoacoustic spectrometer (PAS, 532 nm) as reference device. Especially during the dry period of the campaign, the aerosol population was dominated by pyrogenic emissions. The most pronounced artifact of integrating-plate type attenuation techniques is due to multiple scattering effects within the filter matrix. For the PSAP, we essentially confirmed the laboratory calibration factor by Bond (1999). On the other hand, for the Aethalometer we found a multiple scattering enhancement of 5.23 (or 4.55, if corrected for aerosol scattering), which is significantly larger than the factors previously reported (~2). While the exact reason for this discrepancy is unknown, the available data from the present and previous studies suggest aerosol mixing (internal versus external) as a likely cause. While it is well-known that RH may (moderately) affect aerosol absorption, we found no dependence of either PSAP or Aethalometer on relative humidity (RH) for 30%ambient sampling based on the data from the present and previous studies. For this study, the estimated accuracies of the absorption coefficients determined by the PAS, PSAP and Aethalometer were 10, 15 and 20%, respectively.

Schmid, O.; Artaxo, P.; Arnott, W. P.; Chand, D.; Gatti, L. V.; Frank, G. P.; Hoffer, A.; Schnaiter, M.; Andreae, M. O.

2005-09-01

166

Contributions of fossil fuel, biomass-burning, and biogenic emissions to carbonaceous aerosols in Zurich as traced by 14C  

Microsoft Academic Search

Many open questions exist about the importance of different sources of carbonaceous aerosol, which is a substantial contributor to the global aerosol budget and, therefore, to climate change and human mortality. In this work, 14C was determined in elemental carbon (EC) and different organic carbon (OC) fractions from ambient urban aerosols with aerodynamic diameter <10 ?m collected in Zurich (Switzerland).

Sönke Szidat; Theo M. Jenk; Hans-Arno Synal; Markus Kalberer; Lukas Wacker; Irka Hajdas; Anne Kasper-Giebl; Urs Baltensperger

2006-01-01

167

Contributions of fossil fuel, biomass-burning, and biogenic emissions to carbonaceous aerosols in Zurich as traced by 14C  

Microsoft Academic Search

Many open questions exist about the importance of different sources of carbonaceous aerosol, which is a substantial contributor to the global aerosol budget and, therefore, to climate change and human mortality. In this work, 14C was determined in elemental carbon (EC) and different organic carbon (OC) fractions from ambient urban aerosols with aerodynamic diameter <10 mum collected in Zurich (Switzerland).

Sönke Szidat; Theo M. Jenk; Hans-Arno Synal; Markus Kalberer; Lukas Wacker; Irka Hajdas; Anne Kasper-Giebl; Urs Baltensperger

2006-01-01

168

Evaluations of the chemical mass balance method for determining contributions of gasoline and diesel exhaust to ambient carbonaceous aerosols.  

PubMed

The US. Department of Energy Gasoline/Diesel PM Split Study was conducted to assess the sources of uncertainties in using an organic compound-based chemical mass balance receptor model to quantify the relative contributions of emissions from gasoline (or spark ignition [SI]) and diesel (or compression ignition [CI]) engines to ambient concentrations of fine particulate matter (PM2.5) in California's South Coast Air Basin (SOCAB). In this study, several groups worked cooperatively on source and ambient sample collection and quality assurance aspects of the study but worked independently to perform chemical analysis and source apportionment. Ambient sampling included daily 24-hr PM2.5 samples at two air quality-monitoring stations, several regional urban locations, and along freeway routes and surface streets with varying proportions of automobile and truck traffic. Diesel exhaust was the dominant source of total carbon (TC) and elemental carbon (EC) at the Azusa and downtown Los Angeles, CA, monitoring sites, but samples from the central part of the air basin showed nearly equal apportionments of CI and SI. CI apportionments to TC were mainly dependent on EC, which was sensitive to the analytical method used. Weekday contributions of CI exhaust were higher for Interagency Monitoring of Protected Visual Environments (IMPROVE; 41+/-3.7%) than Speciation Trends Network (32+/-2.4%). EC had little effect on SI apportionment. SI apportionments were most sensitive to higher molecular weight polycyclic aromatic hydrocarbons (indeno[123-cd]pyrene, benzo(ghi)perylene, and coronene) and several steranes and hopanes, which were associated mainly with high emitters. Apportionments were also sensitive to choice of source profiles. CI contributions varied from 30% to 60% of TC when using individual source profiles rather than the composites used in the final apportionments. The apportionment of SI vehicles varied from 1% to 12% of TC depending on the specific profile that was used. Up to 70% of organic carbon (OC) in the ambient samples collected at the two fixed monitoring sites could not be apportioned to directly emitted PM emissions. PMID:17608007

Fujita, Eric M; Campbell, David E; Arnott, William P; Chow, Judith C; Zielinska, Barbara

2007-06-01

169

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

NASA Astrophysics Data System (ADS)

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

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

2009-05-01

170

ON THE EFFECTS OF ELECTROHYDRODYNAMIC FLOWS AND TURBULENCE ON AEROSOL TRANSPORT AND COLLECTION IN WIRE-PLATE ELECTROSTATIC PRECIPITATORS  

Microsoft Academic Search

Predicting transport of aerosols or particles in wire-plate electrostatic precipitators is complicated by the influence of EHD flows and turbulent flow field. In this work we use the direct numerical simulation by Soldati and Banerjee (1998) to analyze the effects of the EHD flows and of turbulence on particle transport and collection efficiency. Particles of different size and charge were

Alfredo Soldati

2000-01-01

171

Characterizing mineral dusts and other aerosols from the Middle East--Part 1: ambient sampling.  

PubMed

The purpose of the Enhanced Particulate Matter Surveillance Program was to provide scientifically founded information on the chemical and physical properties of dust collected over a period of approximately 1 year in Djibouti, Afghanistan (Bagram, Khowst), Qatar, United Arab Emirates, Iraq (Balad, Baghdad, Tallil, Tikrit, Taji, Al Asad), and Kuwait (northern, central, coastal, and southern regions). Three collocated low-volume particulate samplers, one each for the total suspended particulate matter, < 10 micro m in aerodynamic diameter (PM(10)) particulate matter, and < 2.5 micro m in aerodynamic diameter (PM(2.5)) particulate matter, were deployed at each of the 15 sites, operating on a '1 in 6' day sampling schedule. Trace-element analysis was performed to measure levels of potentially harmful metals, while major-element and ion-chemistry analyses provided an estimate of mineral components. Scanning electron microscopy with energy dispersive spectroscopy was used to analyze the chemical composition of small individual particles. Secondary electron images provided information on particle size and shape. This study shows the three main air pollutant types to be geological dust, smoke from burn pits, and heavy metal condensates (possibly from metals smelting and battery manufacturing facilities). Non-dust storm events resulted in elevated trace metal concentrations in Baghdad, Balad, and Taji in Iraq. Scanning-electron-microscopy secondary electron images of individual particles revealed no evidence of freshly fractured quartz grains. In all instances, quartz grains had rounded edges and mineral grains were generally coated by clay minerals and iron oxides. PMID:19235610

Engelbrecht, Johann P; McDonald, Eric V; Gillies, John A; Jayanty, R K M; Casuccio, Gary; Gertler, Alan W

2009-02-01

172

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  

Microsoft Academic Search

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

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

2009-01-01

173

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

PubMed

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. PMID:15696276

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

2005-02-05

174

n-alkanes, fatty acid esters, and fatty acid salts in size fractionated aerosols collected over the Mediterranean Sea  

NASA Astrophysics Data System (ADS)

The n-alkanes, fatty acid esters, and fatty acid salts have been analyzed in size fractionated aerosols collected over the Mediterranean Sea using a five-stage cascade impactor. Two main sources of n-alkanes have been identified: terrestrially derived n-alkanes evenly distributed over the whole particle size spectrum and anthropogenic n-alkanes predominantly carried by submicron particles. The comparison between the fatty acid ester (FAE) and fatty acid salt (FAS) particle size distributions allowed an important contribution to be ascertained of the marine source in aerosols ranging from 7.2 to 3.0 ?m under rough weather conditions that may be due to larger bubble produced particles. In contrast, FAE and FAS were evenly distributed from the first to the fifth stage, when collected during calm sea surface conditions. Higher values of the degree of unsaturation of FAE and FAS were associated with mass concentration maxima observed on stages 2 and 3 in IMP1 aerosol sample whereas lower values were found on the other stages in the same sample, and over the whole particle size spectrum in IMP2 aerosol sample collected during calm weather conditions. THe data we present here are discussed in terms of jet and film drop ejections and degradation processes.

Sicre, M.-A.; Marty, J.-C.; Saliot, A.

175

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

National Technical Information Service (NTIS)

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 smold...

M. A. Mazurek W. R. Cofer J. S. Levine

1990-01-01

176

Towards an experiment to investigate N2O5 uptake to aerosol particles at ambient conditions using the radioactive tracer 13N  

NASA Astrophysics Data System (ADS)

N2O5 is an atmospheric trace gas which plays an important role as a reactive intermediate in the nighttime NOx tropospheric chemistry [1]. N2O5 can function in a dual role: as a NO3 radical reservoir and as a sink for NOx species thanks to the reaction of heterogeneous hydrolysis on aerosol, water and ice surfaces. Therefore N2O5 can have a direct impact on tropospheric ozone production and the oxidizing capacity of the troposphere [1, 2]. Laboratory studies have also shown that uptake of N2O5 to aerosol particles depends on meteorological parameters like temperature and relative humidity as well as aerosol composition [1, 2]. In our experiments we have used the 13N short-lived radioactive tracer technique [3] developed at the Paul Scherrer Institute coupled to an aerosol flow tube reactor. This method allows for the study of N2O5 uptake kinetics to aerosols under realistic conditions, e.g., at ambient pressure and low trace gas concentrations as well as high relative humidity values. Furthermore it allows to observe behavior in a wide temperature range (tropospheric conditions) and the influence of concentration effects on uptake (nitrate effect). Radioactively labeled 13NO is produced in a gas target attached to the Isotope Production Station IP2 at a branch of Injector II at Paul Scherrer Institute and mixed with O3 in the reactor to give 13N2O5. The 13N labeled species formed were monitored by trapping them in a narrow parallel plate diffusion denuder system that allows for selective separation of the gaseous species present and observing the radioactive decay of 13N therein. Activity of N2O5 taken up on aerosol was monitored on a particle filter positioned at the exit of the denuder system. Several denuder coatings were tested for N2O5 and citric acid was selected because of lower interference with NO2. Measurements performed have confirmed formation of 13N labeled N2O5, consistent with predictions obtained via computer modeling. A preliminary study using a citric acid aerosol (whose hygroscopic properties are well known) at relative humidities of 50-80% RH has shown uptake of radioactively labeled N2O5 on the aerosol particles.

Grzinic, G.; Bartels-Rausch, T.; Birrer, M.; Ammann, M.

2012-04-01

177

Determination of oxygenated volatile organic compounds in ambient air using canister collection-gas chromatography/mass spectrometry.  

PubMed

This research attempts to establish a method to measure 11 kinds of oxygenated volatile organic compound (OVOC) in ambient air by using the canister collection-gas chromatography/mass spectrometry (GC/MS) method. Since several compounds such as acetone exhibited high blank concentrations due to their laboratory use, stringent quality control was conducted for the VOC-free added water and the VOC-free nitrogen gas. In order to prevent the decline of recovery rates due to lack of sufficient relative humidity, it is necessary to add VOC-free water when pressurizing and diluting the air samples. Thus, all the target compounds in ambient air were obtained from the canisters at high recovery rates without significant contamination. Furthermore, the canister collection-GC/MS method makes it possible to apply simultaneous air monitoring of OVOCs as well as volatile hazardous air pollutants without additional sampling. PMID:17690433

Hoshi, Jun-Ya; Higuchi, Masato; Sasaki, Yuko; Korenaga, Takashi

2007-08-01

178

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

NASA Astrophysics Data System (ADS)

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.

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

2013-03-01

179

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

PubMed Central

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.

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

2012-01-01

180

A comparative assessment of Boise, Idaho, ambient air fine particle samples using the plate and microsuspension Salmonella mutagenicity assays  

Microsoft Academic Search

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 standard plate assay for monitoring the presence of airborne particle-bound mutagens. Wintertime ambient air particulate samples collected

Larry D Claxton; Sarah Warren; Roy Zweidinger; John Creason

2001-01-01

181

Characterization of Ambient Aerosols in Mexico City during the MCMA-2003 Campaign with Aerosol Mass Spectrometry. Results from the CENICA Supersite  

SciTech Connect

An Aerodyne Aerosol Mass Spectrometer (AMS) was deployed at the CENICA Supersite, while another was deployed in the Aerodyne Mobile Laboratory (AML) during the Mexico City Metropolitan Area field study (MCMA-2003) from March 29-May 4, 2003 to investigate particle concentrations, sources, and processes. This is the first of a series of papers reporting the AMS results from this campaign. The AMS provides real time information on mass concentration and composition of the non-refractory species in particulate matter less than 1 ?m (NR PM1) with high time and size resolution. For the first time, we report field results from a beam width probe, which was used to study the shape and mixing state of the particles and to quantify potential losses of irregular particles due to beam broadening inside the AMS. Data from this probe show that no significant amount of irregular particles was lost due to excessive beam broadening. A comparison of the CENICA and AML AMSs measurements is presented, being the first published intercomparison between two quadrupole AMSs. The speciation, and mass concentrations reported by the two AMSs compared well. In order to account for the refractory material in the aerosol, we also present measurements of Black Carbon (BC) using an aethalometer and an estimate of the aerosol soil component obtained from PIXE analysis of filters. Comparisons of (AMS + BC + soil) mass concentration with other collocated particle instruments (a LASAIR Optical Particle Counter, a Tapered Element Oscillating Microbalance (TEOM) and a DustTrack Aerosol Monitor) are also presented. The comparisons show that the (AMS + BC + soil) mass concentration during MCMC-2003 is a good approximation to the total PM??? mass concentration.

Salcedo, D.; Onasch, Timothy B.; Dzepina, K.; Canagaratna, M. R.; Zhang, Q.; Huffman, A. J.; DeCarlo, Peter; Jayne, J. T.; Mortimer, P.; Worsnop, Douglas R.; Kolb, C. E.; Johnson, Kirsten S.; Zuberi, Bilal M.; Marr, L.; Volkamer, Rainer M.; Molina, Luisa; Molina, Mario J.; Cardenas, B.; Bernabe, R.; Marquez, C.; Gaffney, Jeffrey S.; Marley, Nancy A.; Laskin, Alexander; Shutthanandan, V.; Xie, YuLong; Brune, W. H.; Lesher, R.; Shirley, T.; Jiminez, J. L.

2006-03-24

182

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

PubMed

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. PMID:23938658

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

2013-07-29

183

Organic molecular markers and signature from wood combustion particles in winter ambient aerosols: aerosol mass spectrometer (AMS) and high time-resolved GC-MS measurements in Augsburg, Germany  

NASA Astrophysics Data System (ADS)

The impact of wood combustion on ambient aerosols was investigated in Augsburg, Germany during a winter measurement campaign of a six-week period. Special attention was paid to the high time resolution observations of wood combustion with different mass spectrometric methods. Here we present and compare the results from an Aerodyne aerosol mass spectrometer (AMS) and gas chromatographic - mass spectrometric (GC-MS) analysed PM1 filters on an hourly basis. This includes source apportionment of the AMS derived organic mass by using positive matrix factorisation (PMF) and analysis of levoglucosan as wood combustion marker, respectively. In the measurement period nitrate and organics are the main contributors to the defined submicron particle mass with 28% and 35%, respectively. To the latter wood combustion organic aerosol (WCOA) contributes 23% on average and 27% in the evening and night-time. Conclusively, wood combustion has a strong influence on the organics and overall aerosol composition. Levoglucosan accounts for 14% of WCOA mass with a higher percentage in comparison to other studies. The ratio between the mass of levoglucosan and organic carbon amounts to 0.06. This study is unique in the one-hour time resolution comparison between the wood combustion results of the AMS and the GC-MS analysed filter method at a PM1 particle size range. This comparison of the concentration courses of the PMF WCOA factor, levoglucosan estimated by the AMS data and the levoglucosan measured by GC-MS is highly correlated, and a detailed discussion on the contributors to the wood combustion marker ion at mass-to-charge ratio 60 will be given. This offers a suitable application possibility for the description of the wood combustion course by the WCOA factor and the levoglucosan concentration estimated by AMS data. However, quantitative description of the levoglucosan concentration estimated by the AMS data is difficult due to the offset of latter compared to measured levoglucosan by the GC-MS.

Elsasser, M.; Crippa, M.; Orasche, J.; Decarlo, P. F.; Oster, M.; Pitz, M.; Gustafson, T. L.; Pettersson, J. B. C.; Schnelle-Kreis, J.; Prévôt, A. S. H.; Zimmermann, R.

2012-02-01

184

ATR-FTIR characterization of organic functional groups and inorganic ions in ambient aerosols at a rural site  

NASA Astrophysics Data System (ADS)

An Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopic method was used to measure organic functional groups and inorganic ions at Tonto National Monument (TNM), an Interagency Monitoring of Protected Visual Environments (IMPROVE) sampling site in a rural area near Phoenix, Arizona. Functional groups and ions from common aerosol compound classes such as aliphatic and aromatic CH, methylene, methyl, aldehydes/ketones, carboxylic acids, ammonium sulfate and nitrate as well as functional groups from difficult to measure compound classes such as esters/lactones, acid anhydrides, carbohydrate hydroxyl and ethers, amino acids, and amines were quantified. On average, ˜33% of the PM 1.0 mass was composed of organic aerosol. The average (standard deviation) composition of the organic aerosol at TNM was 34% (6%) biogenic functional groups, 21% (5%) oxygenated functional groups, 28% (7%) aliphatic hydrocarbon functional groups (aliphatic CH, methylene and methyl) and 17% (1%) aromatic hydrocarbon functional groups. Compositional analysis, functional group correlations, and back trajectories were used to identify three types of events with source signatures: primary biogenic-influenced, urban-influenced, and regional background. The biogenic-influenced event had high concentrations of amino acids and carbohydrate hydroxyl and ether, as well as aliphatic CH and aromatic CH functional groups and qualitatively high levels of silicate. The urban-influenced events had back trajectories traveling directly from the Phoenix area and high concentrations of hydrocarbons, oxygenated functional groups, and inorganic ions. This aerosol characterization suggests that both primary emissions in Phoenix and secondary formation of aerosols from Phoenix emissions had a major impact on the aerosol composition and concentration at TNM. The regional background source had low concentrations of all functional groups, but had higher concentrations of biogenic functional groups than the urban source.

Coury, Charity; Dillner, Ann M.

185

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

NASA Astrophysics Data System (ADS)

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.

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

2006-03-01

186

Elemental analysis of aerosols collected at the Pierre Auger Cosmic Ray Observatory with PIXE technique complemented with SEM/EDX  

NASA Astrophysics Data System (ADS)

The aim of this work is to characterize surface aerosols at the Pierre Auger Cosmic Ray Observatory located at Pampa Amarilla, near Malargüe city, in the Andes region of Argentina, with experimental sampling techniques used for the first time in a cosmic ray observatory, adding to information provided by the existing Auger aerosol monitors. A good knowledge of the optical attenuation due to aerosols is crucial for a good reconstruction of the signals from cosmic ray showers detected by the fluorescence detectors of the Observatory. Aerosols were collected in filters, during the Southern Hemisphere winter and spring in 2008. Concentrations in PM2.5 and PM2.5-10 filters were determined by gravimetric analysis and their elemental composition by the PIXE technique, complemented with SEM/EDX. Low aerosol concentrations were measured during the sampling period. The mean total mass PM10 (=PM2.5 + PM2.5-10 fractions) value was [mean(se)] 9.8(1.0) ?g/m3 [sd = 5.9 ?g/m3]. The mean PM10 value during winter was 7(1.1) ?g/m3 [sd = 4.5 ?g/m3], about half of the 13.1(1.5) [sd = 5.7 ?g/m3] measured during springtime. The PM2.5 fraction was approximately 30% of the PM10 fraction. PIXE results gave levels of S, Cl, K, Ca, Ti, Mn, Fe in the analyzed aerosol samples, showing that these elements correspond to 25% and 13% of the PM2.5 and PM2.5-10 total mass respectively. The rest of the mass was due to the elements with low Z (below 16) which cannot be detected by our X-ray setup. Comparison with SEM/EDX analysis showed that most of them were Si and Al (aluminosilicates). Our results indicate that most of the aerosols at the Auger Observatory would most likely come from the soil of the region. Due to its vast atmospheric monitoring network, the Auger Observatory is an interesting reference site for further atmospheric studies.

Micheletti, M. I.; Murruni, L. G.; Debray, M. E.; Rosenbusch, M.; Graf, M.; Ávila Cadena, G.; Vitale, P.; Davidson, J.; Somacal, H.

2012-10-01

187

Semi-automated bacterial spore detection system with micro-fluidic chips for aerosol collection, spore treatment and ICAN DNA detection  

Microsoft Academic Search

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

Hisao Inami; Kouichiro Tsuge; Mitsuhiro Matsuzawa; Yasuhiko Sasaki; Shigenori Togashi; Asuka Komano; Yasuo Seto

2009-01-01

188

Spatial distribution of biogenic sulphur compounds in the Arctic aerosol collected during the AREX 2011 and 2012 Oceania ship cruises  

NASA Astrophysics Data System (ADS)

The sea area between Norway and Svalbard Islands (Norwegian and Greenland Seas) is a critical site to study the effects of the climate change on the high-latitude Northern-Hemisphere regions. In particular, changes in extension and/or in the persistence of annual sea-ice, availability of nutrients and trace-elements in the biological-active marine layers and sea surface temperatures could affect the marine primary productivity and the emission into the atmosphere of dimethylsulphide (DMS), produced by phytoplankton metabolic processes. This volatile compound is oxidised in the atmosphere mainly to sulphuric acid and Methanesulphonic acid (MSA), which undergo gas-to-particle processes and form secondary sub-micrometric aerosol particles. In this way, they play a relevant role as cloud concentration nuclei (CCN), therefore controlling the climate through scattering/absorption of solar irradiation and changes in cloud coverage (and so affecting albedo). Here, we report the spatial distribution of MSA and H2SO4 measured on 12-h aerosol samples (PM10) collected during two summer cruises of the Oceania ship (AREX 2011 and 2012 oceanographic cruises). The samples were collected on Teflon filters along several marine transects starting from Tromso (Norway) to Svalbard Island and along the Western side of Svalbard Islands. S-compounds distribution was also compared with the organic carbon (OC) aerosol fraction, determined by a EC/OC thermo-optical analyser, and with the atmospheric concentration of selected carboxylic acids (measured by ion chromatography). Preliminary results on the AREX 2011 aerosol samples show two sharp maxima of non-sea-salt sulphate and MSA in June, in phase one with each other, while lower contribution of biogenic emission are recorded in the filters collected in July. Besides, no clear trend along coastal to open-sea transects is evident. Higher MSA concentrations (up to 120 ng/m3) were measured near the Norwegian coast, along the Tromso-Svalbard route, and in the south-west coastal areas of the Svalbard Island, while the lowest values (few ng/m3) were found in the open-sea at north-west of the Islands. The Particulate Organic Matter (POM) fraction, reconstructed by the OC measurements, covers about 33% of the PM10 mass, so constituting a major component of the marine Arctic aerosol collected in this area.

Udisti, Roberto; Rugi, Francesco; Becagli, Silvia; Bolzacchini, Ezio; Calzolai, Giulia; Chiari, Massimo; Frosini, Daniele; Ghedini, Costanza; Marconi, Miriam; Grazia Perrone, Maria; Sangiorgi, Giorgia; Severi, Mirko; Traversi, Rita; Walczowski, Waldek; Zielinski, Timon

2013-04-01

189

Total potential source contribution function analysis of trace elements determined in aerosol samples collected near Lake Huron.  

PubMed

Aerosol samples were collected at the rural Burnt Island Ontario Integrated Air Deposition Network air sampling station on the northern shore of Lake Huron from 1992 through 1994. The samples were analyzed for trace elements by neutron activation analysis, and the air concentrations of over 30 elements were determined. Total potential source contribution function analysis (TPSCF) was used to determine the most probable geographical location of these aerosols' origin. The TPSCF results for As, In, Sb, Se, Sn, and Zn are highlighted in this paper. Source regions for these elements ranged from Alma, Quebec, Canada to Carrollton, GA. Because of large seasonal variations in the concentrations of the atmospheric concentrations of these elements, TPSCFvalues were calculated for the summer and winter halves of the year as well as the entire year. PMID:15382853

Biegalski, S R; Hopke, P K

2004-08-15

190

EFFECT OF AN ACTIVATED SLUDGE WASTEWATER TREATMENT PLANT ON AMBIENT AIR DENSITIES OF AEROSOLS CONTAINING BACTERIA AND VIRUSES  

EPA Science Inventory

Bacteria and virus-containing aerosols were studied during late summer and fall in a U.S. midwestern suburb before and during the start up and operation of an unenclosed activated sludge wastewater treatment plant. The air in this suburban area contained low-level densities of in...

191

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

NASA Astrophysics Data System (ADS)

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.

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

2010-05-01

192

Chemical composition and hygroscopic properties of size-segregated aerosol particles collected at the Adriatic coast of Slovenia.  

PubMed

The chemical composition as well as the water uptake characteristics of aerosols was determined in size-segregated samples collected during November 2002 on the Slovenian coast. Major ions, water-soluble organic compounds (WSOC), short-chain carboxylic acids and trace elements were determined in the water-soluble fraction of the aerosol. Total aerosol black carbon (BC) was measured from filter samples. Our results showed that the origin of air masses is an important factor that controls the variation in the size distribution of the main components. Very high concentrations of WSOC as well as higher concentrations of BC were found under mostly continental influence. Besides the main ionic species (SO4(2-), NH4(+), K+) in the finest size fraction (0.17-0.53 microm), the concentration of NO3(-) was also high. The difference between the two different air mass origins is particularly expressed for Cl-, Na+, Mg2+ and Ca2+ determined in particles larger than 1.6 microm. As expected, a very good correlation was found between Na+ and Cl-. A good correlation was found between sea salt elements and elements of crustal origin (Na+, Cl-, Mg2+, Ca2+, Sr). A good relationship between typical anthropogenic tracers (K, V and Pb) was also observed. The mass growth factors, for all size fractions of aerosols collected under continental influence were very low (maximum 2.23 at 94%, 1.6-5.1 microm), while under marine influence the mass growth factors increased significantly with the particle size. At 97% humidity, the mass growth factors were 6.95 for the size fraction 0.53-1.6 microm and 9.78 for larger particles (1.6-5.1 microm). PMID:16289211

Tursic, Janja; Podkrajsek, Bostjan; Grgi?, Irena; Ctyroky, Peter; Berner, Axel; Dusek, Ulrike; Hitzenberger, Regina

2005-11-09

193

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

NASA Astrophysics Data System (ADS)

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 samples induced deposition ice nucleation below 230 K as low as 120% RHice, took up water at about 80% RH, and nucleated subsequently via condensation freezing above 230 K at mean RH of 88-94% and 89-100%, respectively. Experimentally derived ice nucleation rate coefficients and activated IN fractions for estimation of ice crystal production rates are presented. Particles sampled in the L.A. area can induce ice formation at conditions typical for cirrus and mixed-phase clouds and exhibit significantly different ice nucleation efficiencies than particles sampled in and around Mexico City.

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

2011-12-01

194

Chemotactic Sensing towards Ambient and Secreted Attractant Drives Collective Behaviour of E. coli  

PubMed Central

We simulate the dynamics of a suspension of bacterial swimmers, which chemotactically sense gradients in either ambient or self-secreted attractants (e.g. nutrient or aspartate respectively), or in both. Unlike previous mean field models based on a set of continuum partial differential equations, our model resolves single swimmers and therefore incorporates stochasticity and effects due to fluctuations in the bacterial density field. The algorithm we use is simple enough that we can follow the evolution of colonies of up to over a million bacteria for timescales relevant to pattern formation for E. coli growing in semisolid medium such as agar, or in confined geometries. Our results confirm previous mean field results that the patterns observed experimentally can be reproduced with a model incorporating chemoattractant secretion, chemotaxis (towards gradients in the chemoattractant field), and bacterial reproduction. They also suggest that further experiments with bacterial strains chemotactically moving up both nutrient and secreted attractant field may yield yet more dynamical patterns.

Curk, Tine; Marenduzzo, Davide; Dobnikar, Jure

2013-01-01

195

Development of Collection Methods for Semivolatile Organic Compounds in Ambient Air.  

National Technical Information Service (NTIS)

Cartridges containing solid adsorbents between layers of polyurethane foam (PUF) were evaluated for collecting chlorobenzenes, chlorophenols, hexachlorocyclohexanes (HCHs), and two-ring aromatic hydrocarbons. The 26-sq.cm cross-section glass cartridges, p...

T. F. Bidleman M. T. Zaranski G. W. Patton

1987-01-01

196

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...

197

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...

198

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  

Microsoft Academic Search

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 VACES consists of three parallel sampling lines (concentrators), each operating at an intake flow rate of 110lmin?1. Coarse particles are concentrated using

Seongheon Kim; Peter A Jaques; Mingchih Chang; John R Froines; Constantinos Sioutas

2001-01-01

199

Changes in Collection Efficiency in Nylon Net Filter Media Through Magnetic Alignment of Elongated Aerosol Particles  

Microsoft Academic Search

Fiber aerosols tend to align parallel to surrounding fluid streamlines in shear flows, making their filtration more difficult. However, previous research indicates that composite particles made from cromoglycic acid fibers coated with small nanoscaled magnetite particles can align with an applied magnetic field. The present research explored the effect of magnetically aligning these fibers to increase their filtration. Nylon net

Christopher O. Lam; W. H. Finlay

2009-01-01

200

Comparison of Size-Resolved Aerosol Chemical Composition Measurements Made Under Ambient and Low Relative Humidity Conditions at Trinidad Head During the ITCT 2k2 Experiment  

NASA Astrophysics Data System (ADS)

Two co-located, 8-stage rotating drum impactors were deployed at the Trinidad Head site from April 21 - May 26, 2002 as part of the Intercontinental Transport and Chemical Transformation (ITCT) 2k2 experiment. One of the samplers operated at ambient relative humidity while the other had a heated inlet tube that maintained the relative humidity at a low value. The impaction substrates from these samplers were analyzed using synchrotron X-ray fluorescence at the Advanced Light Source (Lawrence Berkeley National Laboratory). The extreme sensitivity of this analytical technique permitted the quantification of nearly all elements between sodium and lead with 3-hour time resolution. The data from these paired samples will be used to show how drying the aerosol affected the mass distribution of the common soil elements, sea salt, and non-sea-salt sulfate at this coastal site.

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

2002-12-01

201

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

SciTech Connect

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 of Nonproliferation and International Security (NIS), National Nuclear Security Administration (NNSA).

Sexton, L.

2012-06-06

202

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)

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.

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

2006-05-01

203

A single-particle characterization of a mobile Versatile Aerosol Concentration Enrichment System for exposure studies  

Microsoft Academic Search

BACKGROUND: An Aerosol Time-of-Flight Mass Spectrometer (ATOFMS) was used to investigate the size and chemical composition of fine concentrated ambient particles (CAPs) in the size range 0.2–2.6 ?m produced by a Versatile Aerosol Concentration Enrichment System (VACES) contained within the Mobile Ambient Particle Concentrator Exposure Laboratory (MAPCEL). The data were collected during a study of human exposure to CAPs, in

Evelyn J Freney; Mathew R Heal; Robert J Donovan; Nicholas L Mills; Kenneth Donaldson; David E Newby; Paul HB Fokkens; Flemming R Cassee

2006-01-01

204

Biological aerosol background characterization  

NASA Astrophysics Data System (ADS)

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.

Blatny, Janet; Fountain, Augustus W., III

2011-05-01

205

Chemotactic Sensing towards Ambient and Secreted Attractant Drives Collective Behaviour of E. coli.  

PubMed

We simulate the dynamics of a suspension of bacterial swimmers, which chemotactically sense gradients in either ambient or self-secreted attractants (e.g. nutrient or aspartate respectively), or in both. Unlike previous mean field models based on a set of continuum partial differential equations, our model resolves single swimmers and therefore incorporates stochasticity and effects due to fluctuations in the bacterial density field. The algorithm we use is simple enough that we can follow the evolution of colonies of up to over a million bacteria for timescales relevant to pattern formation for E. coli growing in semisolid medium such as agar, or in confined geometries. Our results confirm previous mean field results that the patterns observed experimentally can be reproduced with a model incorporating chemoattractant secretion, chemotaxis (towards gradients in the chemoattractant field), and bacterial reproduction. They also suggest that further experiments with bacterial strains chemotactically moving up both nutrient and secreted attractant field may yield yet more dynamical patterns. PMID:24098352

Curk, Tine; Marenduzzo, Davide; Dobnikar, Jure

2013-10-03

206

PM2.5 aerosols collected in the Antarctic Peninsula with a solar powered sampler during austral summer periods  

NASA Astrophysics Data System (ADS)

Collection of PM2.5 particles was carried out in Antarctica in the summer periods of years 2006 and 2007 using solar panels to operate the sampling unit. The unit was installed 2.5 km from the B. O'Higgins Chilean base to avoid possible air contamination from oil or gas burning electric power stations. The aerosols were analyzed by XRF identifying twenty elements between Na and Sr. Results showed the presence of elements of typical Earth crust and seawater origins. In addition, considerable amounts of non-sea sulfur together with traces of Pb and Se from probable long distant anthropogenic activities were observed.

Préndez, M.; Wachter, J.; Vega, C.; Flocchini, R. G.; Wakayabashi, P.; Morales, J. R.

207

DEVELOPMENT OF COLLECTION METHODS FOR SEMIVOLATILE ORGANIC COMPOUNDS IN AMBIENT AIR  

EPA Science Inventory

Cartridges containing solid adsorbents between layers of polyurethane foam (PUF) were evaluated for collecting chlorobenzenes, chlorophenols, hexachlorocyclohexanes (HCHs), and two-ring aromatic hydrocarbons. The 26-sq.cm cross-section glass cartridges, packed with Tenax (5-10 g)...

208

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)

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 the MUs and the filter pack. Using this and results from a previous study, it is concluded that if the MUs and the filter pack were sampling the same particle size, the MUs would have good agreement in terms of precision and accuracy. The MARGA performed moderately well in measuring HNO3 and NH3, though neither met the linear regression slope goals. However, recommendations for improving the measurement of HNO3 and NH3 are discussed. It is concluded that SO42-, SO2, NO3-, HNO3, NH4+ and NH3 concentrations can be measured with acceptable accuracy and precision when the MARGA is operated in conjunction with the recommendations outlined in the manuscript.

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

209

Summertime carbonaceous aerosols collected in the marine boundary layer of the Arctic Ocean  

Microsoft Academic Search

The chemistry, morphology, and microscale to nanoscale structures of carbonaceous aerosols from the marine boundary layer of the Arctic Ocean were investigated by a variety of electron microscopy techniques, including scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and energy-dispersive X-ray spectroscopy (EDS). The relative levels of particles of black carbon (BC) were determined by electron paramagnetic resonance (EPR).

Zhouqing Xie; Joel D. Blum; Satoshi Utsunomiya; R. C. Ewing; Xinming Wang; Liguang Sun

2007-01-01

210

Estimation of size-resolved ambient particle density based on the measurement of aerosol number, mass, and chemical size distributions in the winter in Beijing.  

PubMed

Simultaneous measurements of aerosol size, distribution of number, mass, and chemical compositions were conducted in the winter of 2007 in Beijing using a Twin Differential Mobility Particle Sizer and a Micro Orifice Uniform Deposit Impactor. Both material density and effective density of ambient particles were estimated to be 1.61 ± 0.13 g cm(-3) and 1.62 ± 0.38 g cm(-3) for PM(1.8) and 1.73 ± 0.14 g cm(-3) and 1.67 ± 0.37 g cm(-3) for PM(10). Effective density decreased in the nighttime, indicating the primary particles emission from coal burning influenced the density of ambient particles. Size-resolved material density and effective density showed that both values increased with diameter from about 1.5 g cm(-3) at the size of 0.1 ?m to above 2.0 g cm(-3) in the coarse mode. Material density was significantly higher for particles between 0.56 and 1.8 ?m during clean episodes. Dynamic Shape Factors varied within the range of 0.95-1.13 and decreased with particle size, indicating that coagulation and atmospheric aging processes may change the shape of particles. PMID:22458861

Hu, Min; Peng, Jianfei; Sun, Kang; Yue, Dingli; Guo, Song; Wiedensohler, Alfred; Wu, Zhijun

2012-08-30

211

Changes in collection efficiency in nylon net filter media through magnetic alignment of elongated aerosol particles.  

PubMed

Fiber aerosols tend to align parallel to surrounding fluid streamlines in shear flows, making their filtration more difficult. However, previous research indicates that composite particles made from cromoglycic acid fibers coated with small nanoscaled magnetite particles can align with an applied magnetic field. The present research explored the effect of magnetically aligning these fibers to increase their filtration. Nylon net filters were challenged with the aerosol fibers, and efficiency tests were performed with and without a magnetic field applied perpendicular to the flow direction. We investigated the effects of varying face velocities, the amount of magnetite material on the aerosol particles, and magnetic field strengths. Findings from the experiments, matched by supporting single-fiber theories, showed significant efficiency increases at the low face velocity of 1.5 cm s(-1) at all magnetite compositions, with efficiencies more than doubling due to magnetic field alignment in certain cases. At a higher face velocity of 5.12 cm s(-1), filtration efficiencies were less affected by the magnetic field alignment being, at most, 43% higher for magnetite weight compositions up to 30%, while at a face velocity of 10.23 cm s(-1) alignment effects were insignificant. In most cases, efficiencies became independent of magnetic field strength above 50 mT, suggesting full alignment of the fibers. The present data suggest that fiber alignment in a magnetic field may warrant applications in the filtration and detection of fibers, such as asbestos. PMID:19693722

Lam, Christopher O; Finlay, W H

2009-10-01

212

Use of bioassay methods to evaluate mutagenicity of ambient air collected near a municipal-waste combustor  

SciTech Connect

An ambient air sampling study was conducted around a municipal waste combustor with a primary goal being to develop procedures to evaluate the emissions of organic mutagens resulting from incomplete combustion of municipal waste. The products of incomplete combustion from incineration include complex mixtures of organics, particularly polycyclic aromatic compounds, which are present after atmospheric dilution and cooling in emissions as semi-volatile or particle bound organic compounds. Combustion emissions are generally recognized as a potential cancer risk since they contain many carcinogenic and mutagenic polycyclic aromatic hydrocarbons. Analyzing such a complex mixture for the presence of even a few selected chemicals is difficult and provides risk information on only a fraction of the chemicals present. Bioassay methods, however, may be directly applied to evaluate the mutagenic and carcinogenic activity of the complex organics from combustion emissions. The Salmonella (Ames) assay was used to determine the mutagenicity associated with particles from ambient air collected near a municipal waste combustor. Dose-response data was generated, and mutagenicity concentrations were calculated to demonstrate the utility of bioassay in assessing emissions from municipal waste combustion.

Watts, R.; Fitzgerald, B.; Heil, G.; Garabedian, H.; Williams, R.

1989-04-28

213

Organic molecular markers and signature from wood combustion particles in winter ambient aerosols: aerosol mass spectrometer (AMS) and high time-resolved GC-MS measurements in Augsburg, Germany  

NASA Astrophysics Data System (ADS)

The impact of wood combustion on ambient aerosols was investigated in Augsburg, Germany during a winter measurement campaign of a six-week period. Special attention was paid to the high time resolution observations of wood combustion with different mass spectrometric methods. Here we present and compare the results from an Aerodyne aerosol mass spectrometer (AMS) and gas chromatographic - mass spectrometric (GC-MS) analysed PM1 filters on an hourly basis. This includes source apportionment of the AMS derived organic matter (OM) using positive matrix factorisation (PMF) and analysis of levoglucosan as wood combustion marker, respectively. During the measurement period nitrate and OM mass are the main contributors to the defined submicron particle mass of AMS and Aethalometer with 28% and 35%, respectively. Wood combustion organic aerosol (WCOA) contributes to OM with 23% on average and 27% in the evening and night time. Conclusively, wood combustion has a strong influence on the organic matter and overall aerosol composition. Levoglucosan accounts for 14% of WCOA mass with a higher percentage in comparison to other studies. The ratio between the mass of levoglucosan and organic carbon amounts to 0.06. This study is unique in that it provides a one-hour time resolution comparison between the wood combustion results of the AMS and the GC-MS analysed filter method at a PM1 particle size range. The comparison of the concentration variation with time of the PMF WCOA factor, levoglucosan estimated by the AMS data and the levoglucosan measured by GC-MS is highly correlated (R2 = 0.84), and a detailed discussion on the contributors to the wood combustion marker ion at mass-to-charge ratio 60 is given. At the end, both estimations, the WCOA factor and the levoglucosan concentration estimated by AMS data, allow to observe the variation with time of wood combustion emissions (gradient correlation with GC-MS levoglucosan of R2 = 0.84). In the case of WCOA, it provides the estimated magnitude of wood combustion emission. Quantitative estimation of the levoglucosan concentration from the AMS data is problematic due to its overestimation in comparison to the levoglucosan measured by the GC-MS.

Elsasser, M.; Crippa, M.; Orasche, J.; DeCarlo, P. F.; Oster, M.; Pitz, M.; Cyrys, J.; Gustafson, T. L.; Pettersson, J. B. C.; Schnelle-Kreis, J.; Prévôt, A. S. H.; Zimmermann, R.

2012-07-01

214

Distributions of low molecular weight dicarboxylic acids, ketoacids and ?-dicarbonyls in the marine aerosols collected over the Arctic Ocean during late summer  

NASA Astrophysics Data System (ADS)

Oxalic and other small dicarboxylic acids have been reported as important water-soluble organic constituents of atmospheric aerosols from different environments. Their molecular distributions are generally characterized by the predominance of oxalic acid (C2) followed by malonic (C3) and/or succinic (C4) acids. In this study, we collected marine aerosols from the Arctic Ocean during late summer in 2009 when sea ice was retreating. The marine aerosols were analyzed for the molecular distributions of dicarboxylic acids as well as ketocarboxylic acids and ?-dicarbonyls to better understand the source of water-soluble organics and their photochemical processes in the high Arctic marine atmosphere. We found that diacids are more abundant than ketoacids and ?-dicarbonyls, but their concentrations are generally low (< 30 ng m-3), except for one sample (up to 70 ng m-3) that was collected near the mouth of Mackenzie River during clear sky condition. Although the molecular compositions of diacids are in general characterized by the predominance of oxalic acid, a depletion of C2 was found in two samples in which C4 became the most abundant. Similar depletion of oxalic acid has previously been reported in the Arctic aerosols collected at Alert after polar sunrise and in the summer aerosols from the coast of Antarctica. Because the marine aerosols that showed a depletion of C2 were collected under the overcast and/or foggy conditions, we suggest that a photochemical decomposition of oxalic acid may have occurred in aqueous phase of aerosols over the Arctic Ocean via the photo dissociation of oxalate-Fe (III) complex. We also determined stable carbon isotopic compositions (?13C) of bulk aerosol carbon and individual diacids. The ?13C of bulk aerosols showed -26.5‰ (range: -29.7 to -24.7‰, suggesting that marine aerosol carbon is derived from both terrestrial and marine organic materials. In contrast, oxalic acid showed much larger ?13C values (average: -20.9‰, range: -24.7‰ to -17.0‰) than those of bulk aerosol carbon. Interestingly, ?13C values of oxalic acid were higher than C3 (av. -26.6‰) and C4 (-25.8‰) diacids, suggesting that oxalic acid is enriched with 13C due to its photochemical processing (aging) in the marine atmosphere.

Kawamura, K.; Ono, K.; Tachibana, E.; Charriére, B.; Sempéré, R.

2012-11-01

215

Chemical characterization of aerosol collected at Mt. Yulong in wintertime on the southeastern Tibetan Plateau  

NASA Astrophysics Data System (ADS)

In order to evaluate the chemical composition of aerosol on the southeastern Tibetan Plateau, aerosol samples were acquired at Mt. Yulong during January to February, 2010. Eighteen elements (Al, Si, P, S, Ca, Ti, K, Cr, Mn, Fe, Ni, Zn, As, Br, Ba, Pb, Sb and Cu) and major water-soluble ions (SO42 -, NO3-, Cl-, Na+, NH4+, K+, Mg2 +, and Ca2 +) were detected. The results show that Ca, Fe, Al, Si, S, K and Ti are major elements which mainly originate from crustal material, while SO42 - and Ca2 + are the dominant anion and cation in the samples, respectively. Results of ion analysis indicate that our samples are alkaline and that the main compounds present are CaCO3, (NH4)2SO4, and CaSO4. The enrichment factors (EFs) determined for As, Br, Ca, Cu, S, Pb and Zn are greater than 10; in particular, EFs for As and Br are above 100. However, the high EF for As could be caused by crustal sources because the high level of As enrichment can be found commonly on the Tibetan Plateau. Analyses including Scanning Electron Microscope (SEM) observations, EF determinations, backward trajectories and correlation coefficients reveal that Al, Fe, Ca, Ti, Mn, Fe, K and Mg2 + mainly originate from crustal sources; Pb, Br, Cu, Ni, Zn and Sb come mainly from traffic-related emissions; and biomass burning influences Cl-, Br, S and P.

Zhang, Ningning; Cao, Junji; Ho, Kinfai; He, Yuanqing

2012-04-01

216

Monitoring of inorganic ions, carbonaceous matter and mass in ambient aerosol particles with online and offline methods  

NASA Astrophysics Data System (ADS)

Year-long high timeresolution measurements of major chemical components in atmospheric sub-micrometer particles were conducted at an urban background station in Finland 2006-2007. Ions were analyzed using a particle-into-liquid sampler combined with an ion chromatograph (PILS-IC), organic and elemental carbon (OC and EC) by using a semicontinuos OC/EC aerosol carbon analyzer (RT-OCEC), and PM2.5 mass with a tapered element oscillating microbalance (TEOM). Long time series provides information on differences between the used measurement techniques as well as information about the diurnal and seasonal changes. Chemical mass closure was constructed by comparing the identified aerosol mass with the measured PM2.5. The sum of all components measured online (ions, particulate organic matter (POM), EC) represented only 65% of the total PM2.5 mass. The difference can be explained by the difference in cutoff sizes (PM1 for online measurements, PM2.5 for total mass) and by evaporation of the semivolatile/volatile components. In general, some differences in results were observed when the results of the continuous/semicontinuous instruments were compared with those of the conventional filter samplings. For non-volatile compounds, like sulfate and potassium, correlation between the filter samples and the PILS was good but greater differences were observed for the semivolatile compounds like nitrate and ammonium. For OC the results of the RT-OCEC were on average 10% larger than those of the filters. When compared to filter measurements, high resolution measurements provide important data on short pollution plumes as well as on diurnal changes. Clear seasonal and diurnal cycles were observed for nitrate and EC.

Timonen, H.; Aurela, M.; Saarnio, K.; Frey, A.; Saarikoski, S.; Teinilä, K.; Kulmala, M.; Hillamo, R.

2011-10-01

217

Development of infrared photothermal deflection spectroscopy (mirage effect) for analysis of condensed-phase aerosols collected in a micro-orifice uniform deposit impactor.  

PubMed

The potential of mid-infrared photothermal deflection spectrometry for aerosol analysis is demonstrated. Ammonium nitrate aerosols are deposited on a flat substrate using a micro-orifice uniform deposit impactor (MOUDI). Photothermal spectroscopy with optical beam deflection (mirage effect) is used to detect deposited aerosols. Photothermal deflection from aerosols is measured by using pulsed infrared laser light to heat up aerosols collected on the substrate. The deflection signal is obtained by measuring the position of a spot from a beam of light as it passes near the heated surface. The results indicate non-rotating impaction as the preferred MOUDI impaction method. Energy-dependent photothermal measurement shows a linear relationship between signal and laser intensity, and no loss of signal with time is observed. The detection limit from the signal-mass curve is 7.31 ng. For 30 minutes collection time and 30 L/min flow rate of the impactor, the limit of detection in terms of aerosol mass concentration is 0.65 microg m(-3). PMID:19094392

Dada, Oluwatosin O; Bialkowski, Stephen E

2008-12-01

218

Distributions of low molecular weight dicarboxylic acids, ketoacids and ?-dicarbonyls in the marine aerosols collected over the Arctic Ocean during late summer  

NASA Astrophysics Data System (ADS)

Oxalic and other small dicarboxylic acids have been reported as important water-soluble organic constituents of atmospheric aerosols from different environments. Their molecular distributions are generally characterized by the predominance of oxalic acid (C2) followed by malonic (C3) and/or succinic (C4) acids. In this study, we collected marine aerosols from the Arctic Ocean during late summer in 2009 when sea ice is retreated. The marine aerosols were analyzed for the molecular distributions of dicarboxylic acids as well as ketocarboxylic acids and ?-dicarbonyls to better understand the source of water-soluble organics and their photochemical processes in the high Arctic marine atmosphere. We found that diacids are more abundant than ketoacids and ?-dicarbonyls, but their concentrations are generally low (< 30 ng m-3), except for one sample (up to 70 ng m-3) that was collected near the mouth of Mackenzie River during clear sky condition. Although the molecular compositions of diacids are in general characterized by the predominance of oxalic acid, a depletion of C2 was found in two samples in which C4 became the most abundant. Similar depletion of oxalic acid has previously been reported in the Arctic aerosols collected at Alert after polar sunrise and in the summer aerosols from the coastal Antarctica. Because the marine aerosols that showed a depletion of C2 were observed under the overcast and/or foggy conditions, we suggest that a photochemical decomposition of oxalic acid may have occurred in aqueous phase of aerosols over the Arctic Ocean via the photo dissociation of oxalate-Fe (III) complex. We also determined stable carbon isotopic compositions (?13C) of bulk aerosol carbon and individual diacids. The ?13C of bulk aerosols showed -26.5‰ (range: -29.7‰ to -24.7‰), suggesting that marine aerosol carbon is derived from both terrestrial and marine organic materials. In contrast, oxalic acid showed much larger ?13C values (average: -20.9‰, range: -24.7‰ to -17.0‰) than those of bulk aerosol carbon. Interestingly, ?13C values of oxalic acid were higher than C3 (av. -26.6‰) and C4 (-25.8‰) diacids, suggesting that oxalic acid is enriched with 13C due to its photochemical processing (aging) in the marine atmosphere.

Kawamura, K.; Ono, K.; Tachibana, E.; Charriére, B.; Sempéré, R.

2012-08-01

219

Organosulfate formation in biogenic secondary organic aerosol.  

PubMed

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 that the organosulfate contribution to the total organic mass fraction of ambient aerosol collected from K-puszta, Hungary, a field site with a similar organosulfate composition as that found in the present study for the southeastern U.S., can be as high as 30%. PMID:18710205

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

2008-08-19

220

Ambient air sampling for tritium--determination of breakthrough volumes and collection efficiencies for silica gel adsorbent  

SciTech Connect

Ambient air samples for tritium (as HTO) can be collected using the solid adsorbent silica gel. The purpose of this study was to determine the maximum practical sampling volume and overall collection efficiency for water vapor collected on silica gel columns and to demonstrate the use of an impinger-based system to load water vapor onto silica gel columns. Breakthrough volumes (V{sub b}) were measured and chromatographic efficiencies (expressed as the number of theoretical plates, N) were calculated for a 20{degrees}C to 50{degrees}C temperature range, with the relative humidity at approximately 30%. The tests yielded relative breakthrough volumes (air volume/adsorbent depth, m{sup 3} cm{sup -1}) of 0.36 for 20{degrees}C, 0.20 for 30{degrees}C, 0.15 for 40{degrees}C, and 0.077 for 50{degrees}C. For 18-cm columns, the average tritium tracer recoveries at 20{degrees}C were 71% with no observed breakthrough for air volumes up to 5 m{sup 3}, while at 40{degrees}C mean tritium tracer recoveries dropped from 75% for volumes {le}3.0 m{sup 3}, to 0% for a volume of 5.0 m{sup 3}. Frontal chromatographic profiles were measured for water vapor migrating through silica gel columns that were divided into 5 segments. The chromatographic efficiency of the silica gel columns was determined by graphical evaluation of the chromatography profiles. At a sampling rate of 0.25 L min{sup -1} and 30% relative humidity, the number of theoretical plates per adsorbent depth were 0.55 N cm{sup -1} at 20{degrees}C, 0.68 N cm{sup -1} at 30{degrees}C, 0.51 N cm{sup -1} at 40{degrees}C, and 0.30 N cm{sup -1} at 50{degrees}C. Chromatographic theory was used to estimate the overall collection efficiency of the silica gel columns as a function of the ratio of the sampling volume to breakthrough volume and the chromatographic efficiency. 16 refs., 11 figs., 6 tabs.

Patton, G.W.; Cooper, A.T. Jr.; Tinker, M.R. [Pacific Northeast Lab., Richland, WA (United States)

1997-03-01

221

Spectral light absorption by ambient aerosols influenced by biomass burning in the Amazon Basin I. Comparison and field calibration of absorption measurement techniques  

Microsoft Academic Search

Spectral aerosol light absorption is an important parameter for the assessment of the radiation budget of the atmosphere. Although on-line measurement techniques for aerosol light absorption, such as the Aethalometer and the Particle Soot Absorption Photometer (PSAP), have been available for two decades, they are limited in accuracy and spectral resolution because of the need to deposit the aerosol on

O. Schmid; P. Artaxo; W. P. Arnott; D. Chand; L. V. Gatti; G. P. Frank; A. Hoffer; M. Schnaiter; M. O. Andreae

2005-01-01

222

Spectral light absorption by ambient aerosols influenced by biomass burning in the Amazon Basin. I: Comparison and field calibration of absorption measurement techniques  

Microsoft Academic Search

Spectral aerosol light absorption is an important parameter for the assessment of the radiation budget of the atmosphere. Although on-line measurement techniques for aerosol light absorption, such as the Aethalometer and the Particle Soot Absorption Photometer (PSAP), have been available for two decades, they are limited in accuracy and spectral resolution because of the need to deposit the aerosol on

O. Schmid; P. Artaxo; W. P. Arnott; D. Chand; L. V. Gatti; G. P. Frank; A. Hoffer; M. Schnaiter; M. O. Andreae

2006-01-01

223

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...

224

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

PubMed Central

Satellite-based PM2.5 monitoring has the potential to complement ground PM2.5 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 PM2.5 concentrations. However, previous studies have shown that AOD may not be a strong predictor of PM2.5 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 PM2.5 concentrations. First, we render AOD a robust predictor of PM2.5 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 PM2.5 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 PM2.5 concentrations for both retrieval days (i.e., days with satellite data available) and non-retrieval days in the New England region of the U.S. during the period 2000-2008. Overall, for the years 2000-2008, our statistical models predicted surface PM2.5 concentrations with reasonably high R2 (0.83) and low percent mean relative error (3.5%). Also the spatial distribution of the estimated PM2.5 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 tremendous impact on the fields of environmental monitoring and human exposure assessment.

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

2012-01-01

225

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

SciTech Connect

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.

Anheier, Norman C.; Bushaw, Bruce A.

2010-08-11

226

Size distributions of dicarboxylic acids and inorganic ions in atmospheric aerosols collected during polar sunrise in the Canadian high Arctic  

NASA Astrophysics Data System (ADS)

Size-segregated atmospheric aerosols (11 stages separating particles from <0.04 to >14.2 ?m) collected in the Arctic during the polar sunrise at Alert were analyzed for aerosol mass, dicarboxylic acids, and major inorganic ions. Oxalic, malonic, succinic, and glutaric acids were detected in all size ranges, with oxalic acid being dominant. Their concentrations maximized in the accumulation mode either at 0.24-0.40 or 0.40-0.8 ?m aerodynamic diameters, suggesting that diacids were mainly formed by gas-to-particle conversion via photochemical oxidation of nonmethane hydrocarbons and oxygenated organics originated from continental pollution sources. The relative abundances of oxalic acid were higher in the 0.24- to 0.4-?m size particles (73-78%) than in supermicrometer particles (40-60%), indicating that oxalic acid is produced by gas phase oxidation of precursors followed by accumulation on preexisting particles. Mass size distributions of NH4+ and SO42- peaked in the accumulation mode similar to those of small diacids. The sea-salt enrichment factor of K+ (biomass burning tracer) relative to Na+ maximized in 0.1- to 0.8-?m sizes, whereas those of Mg2+ and Ca2+ (dust tracers) in 0.4- to 7.8-?m particles. Maximized chlorine loss and bromine enrichment were found at 0.4-0.8 and 0.24-0.4 ?m sizes, respectively. Concentrations of Br-, which typically showed a submicrometer maximum, increased significantly during an O3 depletion event having a shift of size distribution to a supermicrometer mode. During this event, oxalic acid concentration relative to succinic acid increased in submicrometer mode (0.24-0.4 ?m), adding to a growing body of evidence supporting the hypothesis that halogen chemistry is important in the production and loss of oxalic acid in the arctic atmosphere.

Kawamura, Kimitaka; Narukawa, Masahiro; Li, Shao-Meng; Barrie, Leonard A.

2007-05-01

227

An investigation into the acid content of aerosols in the ambient air at the Taj Mahal, Agra.  

PubMed

A chemical analysis of suspended particulate matter (SPM) collected near the world famous Taj Mahal monument at Agra has been carried out. SPM samples collected on glass fibre filters were analysed for water-soluble sulphate, nitrate, chloride and ammonium ions. The data were derived from over 200 samples (each of 24 h), collected continuously during the winter periods (October through to March) of 1984-1985 and 1985-1986. The SO(4)(2-) and NO(3)(-) components are acidic in nature causing corrosion and effects on visibility, and so were studied in more detail. Mean values for SO(4)(2-) and NO(3)(-) derived from two-year data are 7.2 microg m(-3) and 8.2 microg m(-3), respectively. The SO(4)(2-)/SO(2) and NO(3)(-)/NO(2) ratiosobserved indicate faster conversion of SO(2) to SO(4)(2-) than NO(2) to NO(3)(-), the maximum levels being in January. Thus, both SO(4)(2-) and NO(3)(-) results appear to offer more promising indices of air quality than do SPM data alone. PMID:15092423

Joshi, S D; Pandya, G H; Phadke, K M; Tajne, D S; Jain, A K; Gajrani, C P; Yennawar, P K

1989-01-01

228

a Study of the Origin of Atmospheric Organic Aerosols  

NASA Astrophysics Data System (ADS)

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 predictions and ambient concentrations that could be due to atmospheric chemical reaction are discussed. An upper limit on the amount of secondary organic aerosol present is estimated based on the difference between the acidic organic aerosol present in ambient samples versus that due to primary emissions as computed by the model. Finally, several hypotheses concerning the origin of the organic aerosol are proposed.

Hildemann, Lynn Mary

1990-01-01

229

Measurement of Ambient Elemental Carbon Using the Thermal-Optical Transmittance Technique: Effect of Sample Volume and Refractory Loading on the OC\\/EC Split  

Microsoft Academic Search

Ambient carbonaceous aerosols have been measured on a daily basis in Pittsburgh, PA for over a year. A discrepancy is observed when comparing ambient elemental carbon (EC) levels from samples collected over a 24-hour period to those measured at a higher frequency. For example, the 24-hr average EC calculated from 5 high frequency samples of 4 to 6 hour duration

R. Subramanian; A. Y. Khlystov; B. J. Turpin; A. L. Robinson

2002-01-01

230

Aerosol mass spectrometer measurements of organic aerosol  

Microsoft Academic Search

Organic species are known to be ubiquitous and comprise a significant component of ambient aerosols. Identifying the sources, chemical compositions, and loadings of particulate organics remains a difficult, yet important problem as organic components may affect the formation, hygroscopicity, growth, reactivity, and radiative effects of ambient particles. Unraveling this complexity inherently must rely on chemical information (such as off-line filter

D. Worsnop; M. Canagaratna; J. Jayne; H. Boudries; T. Onasch; J. Jimenez; J. Slowik; H. Coe

2003-01-01

231

Efficiency of a Low-Energy Wetted-Surface Multi-Annulus Denuder Sampler for Viable and Nonviable Aerosol Collection  

Microsoft Academic Search

Capture efficiency of a wetted-surface low-energy sampler (LES) was evaluated for polystyrene latex (PSL) microsphere aerosol and a Bacillus subtilis aerosol. The observed absolute capture efficiency for PSL microspheres was higher than predicted by theory for the particle sizes used (0.7, 1.6, and 3.0 ?m), suggesting hygroscopic particle growth via water uptake by residual detergent coatings. Bio-aerosol capture efficiency was

D. L. Johnson; T. A. Pearce

1998-01-01

232

Study Of The Elemental Composition Of Atmospheric Aerosols Collected In The Auger South Observatory Of Cosmic Rays, By Using The PIXE Technique  

NASA Astrophysics Data System (ADS)

We applied the PIXE (Particle-Induced X-ray Emission) technique to samples of atmospheric aerosols collected in filters in the Auger South Observatory, Malargüe, Argentina, with instrument Andersen Graseby 240. We analyzed the concentration PM2.5, PM2.5-10 and PM10 by gravimetric analysis and the elemental composition of fine (size <2.5 ?m) and coarse (size between 2.5 ?m and 10 ?m) particles by PIXE technique. We complemented the elemental study with microscopic analysis, SEM/EDX. We discuss the concentration levels in the region, which in general are very low. We focus our analysis in winter and spring results. We find that concentration levels increase with increasing temperatures in the region. Most chemical elements have higher elemental concentrations in the coarse aerosols, but sulfur has higher elemental concentrations in fine aerosols.

Micheletti, M. I.; Graf, M.; Debray, M.; Murruni, L.; Ávila Cadena, G.; Vitale, P.; Davidson, J.; Piacentini, R. D.; Rosenbusch, M.; Somacal, H.

2010-08-01

233

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)

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.

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

2013-10-01

234

Size distribution, state of mixture and morphology of urban aerosol particles at given electrical mobilities  

Microsoft Academic Search

Aerosol particles were collected in Tsukuba, Japan with an impactor in ambient air downstream of a differential mobility analyzer (DMA) at three electrical mobility diameters of 200, 300 and 400nm in dry conditions (relative humidity of <3%). The particles collected on a silicone-oil coated film were examined by electron microscopy in order to obtain the diameter, shape and volatility properties

Kikuo Okada; Jost Heintzenberg

2003-01-01

235

Survival of bacteria during aerosolization.  

PubMed Central

One form of commercial application of microorganisms, including genetically engineered microorganisms is as an aerosol. To study the effect of aerosol-induced stress on bacterial survival, nonrecombinant spontaneous antibiotic-resistant mutants of four organisms, Enterobacter cloacae, Erwinia herbicola, Klebsiella planticola, and Pseudomonas syringae, were sprayed in separate experiments in a greenhouse. Samples were collected over a distance of 15 m from the spray site for enumeration. Spores of Bacillus subtilis were used as tracers to estimate the effects of dilution on changes in population over distance. Viable counts of P. syringae, Enterobacter cloacae, and K. planticola decreased significantly over a distance of 15 m. Erwinia herbicola showed no significant decline in counts over the same distance. The degree of survival of P. syringae during aerosolization was dependent on ambient environmental conditions (i.e., temperature, relative humidity), droplet size of the aerosol, and prior preparative conditions. Survival was greatest at high relative humidities (70 to 80%) and low temperatures (12 degrees C). Survival was reduced when small droplet sizes were used. The process of washing the cells prior to aerosolization also caused a reduction in their survival. Results from these experiments will be useful in developing sound methodologies to optimize enumeration and for predicting the downwind dispersal of airborne microorganisms, including genetically engineered microorganisms.

Marthi, B; Fieland, V P; Walter, M; Seidler, R J

1990-01-01

236

Elemental content of PM2.5 aerosol particles collected in Göteborg during the Göte-2005 campaign in February 2005  

NASA Astrophysics Data System (ADS)

The Göte-2005 measurement campaign aimed at studying the influence of the winter thermal inversions on urban air pollution. Elemental speciation of PM2.5 aerosol particles, collected on Teflon filters at three urban sites and one rural site in the Göteborg region, was a major part of the study. Trace element analysis was done by Energy Dispersive X-Ray Fluorescence (EDXRF) spectrometry and the concentrations of S, Cl, K, Ca, Ti, V, Mn, Fe, Ni, Cu, Zn, Br and Pb were determined. The elemental content of the particles, local wind speed and direction, and backward trajectories were used to investigate possible sources for the pollutants. We concluded that S, V, Ni, Br, and Pb had their main sources outside the central Göteborg area, since elevated concentrations of these elements were not observed during an inversion episode. Sea traffic and harbour activities were identified, primarily by the S and V content of the particles. This study showed that the elemental analysis by EDXRF presents valuable information for tracing the origin of air masses arriving at a measurement site.

Boman, J.; Gatari, M. J.; Janhäll, S.; Shannigrahi, A. S.; Wagner, A.

2009-04-01

237

Elemental content of PM2.5 aerosol particles collected in Göteborg during the Göte-2005 campaign in February 2005  

NASA Astrophysics Data System (ADS)

Göte-2005 was a measurement campaign in the city of Göteborg with the aim of studying the influence of the winter thermal inversions on urban air pollution. Elemental speciation of PM2.5 aerosol particles, collected on Teflon filters at three urban sites and one rural site in the Göteborg region, was a major part of the study. Trace element analysis was done by Energy Dispersive X-Ray Fluorescence (EDXRF) spectrometry and the concentrations of S, Cl, K, Ca, Ti, V, Mn, Fe, Ni, Cu, Zn, Br and Pb were determined. The elemental content of the particles in combination with information of local wind speed and direction and also backward trajectories were used to estimate the source areas of the pollutants. We can conclude that S, V, Ni, Br, and Pb have their main sources outside the Göteborg area, since we cannot see elevated concentrations of these elements during an inversion episode. Sea traffic and harbour activities were also identified, primarily by the S and V content of the particles. This study proves that the elemental analysis by EDXRF presents valuable information for tracing the origin of air masses arriving at a measurement site.

Boman, J.; Gatari, M. J.; Janhäll, S.; Shannigrahi, A. S.; Wagner, A.

2008-04-01

238

Use of spaceborne lidar for the evaluation of thin cirrus contamination and screening in the Aqua MODIS Collection 5 aerosol products  

NASA Astrophysics Data System (ADS)

Cloud contamination from subvisual thin cirrus clouds is still a challenging issue for operational satellite aerosol retrievals. In the A-Train constellation, concurrent high-sensitivity cirrus observations from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) provide us with an unprecedented opportunity to examine the susceptibility of the Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol retrievals to thin cirrus contamination and to evaluate the robustness of various cirrus screening techniques. Quantitative evaluations indicate that the current cirrus screening schemes in the MODIS Dark Target and Deep Blue Collection 5 aerosol retrievals can effectively remove most cirrus signals while some residual thin cirrus signals still exist with strong spatial and seasonal variability. Results also show significant linkage between thin cirrus occurrence frequency and the susceptibility of aerosol retrievals to thin cirrus contamination. Using the CALIPSO cirrus observations as a reference, we also examined the effectiveness and robustness of eight MODIS-derived cirrus screening parameters. These parameters include apparent reflectance at 1.38 µm (R1.38), cirrus reflectance at 0.66 µm (CR0.66), CR0.66 cirrus flag (CF), reflectance ratio between 1.38 µm and 0.66 µm (RR1.38/0.66), reflectance ratio between 1.38 µm and 1.24 µm (RR1.38/1.24), brightness temperature difference between 8.6 µm and 11 µm (BTD8.6-11), brightness temperature difference between 11 µm and 12 µm (BTD11-12), and cloud phase infrared approach (CPIR). Among these parameters, RR1.38/0.66 achieves the best overall performance, followed by the BTD11-12. Results from several test cases suggest that the cirrus screening schemes in the operational MODIS aerosol retrieval algorithms can be further improved to reduce thin cirrus contamination.

Huang, Jingfeng; Hsu, N. Christina; Tsay, Si-Chee; Liu, Zhaoyan; Jeong, Myeong-Jae; Hansell, Richard A.; Lee, Jaehwa

2013-06-01

239

Investigation of the Efficiencies of Bioaerosol Samplers for Collecting Aerosolized Bacteria Using a Fluorescent Tracer. II: Sampling Efficiency and Half-Life Time  

Microsoft Academic Search

Using uranine as a physical tracer, this study assessed the sampling efficiencies of four bioaerosol samplers (Andersen 6-stage impactor, all glass impinger “AGI-30,” OMNI-3000, and Airport MD8 with gelatin filter) for collecting Gram-positive bacteria (Enterococcus faecalis), Gram-negative bacteria (Escherichia coli and Campylobacter jejuni), and bacteria without cell wall (Mycoplasma synoviae) which were aerosolized in a HEPA isolator. In addition, the

Yang Zhao; Andre J. A. Aarnink; Piet Doornenbal; Thuy T. T. Huynh; Peter W. G. Groot Koerkamp; Wil J. M. Landman; Mart C. M. de Jong

2011-01-01

240

Trends in Aerosol Abundances and Distributions.  

National Technical Information Service (NTIS)

The properties of aerosols that reside in the upper atmosphere are described. Special emphasis is given to the influence these aerosols have on ozone observation systems, mainly through radiative effects, and on ambient ozone concentrations, mainly throug...

R. P. Turco M. P. Mccormick R. T. Clancy R. Curran J. Deluisi

1989-01-01

241

RESPIRATORY DEPOSITION OF POLYDISPERSE AEROSOLS IN HUMANS  

EPA Science Inventory

Ambient aerosols constitute particles with varying sizes from ultrafine to coarse particles. Because of a lack of experimental data, deposition of these heterogeneous aerosols is, almost exclusively, estimated by mathematical models. However, the models have never been validated ...

242

Physical and chemical characterization of ambient aerosol by HR-ToF-AMS at a suburban site in Hong Kong during springtime 2011  

NASA Astrophysics Data System (ADS)

An Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) has been employed in a field sampling campaign at a suburban coastal site in Hong Kong in springtime 2011 to provide insights into the size-resolved chemical composition of nonrefractory submicron aerosol species. This is the first time that such detailed real-time measurements have been made in Hong Kong. The total nonrefractory PM1 was dominated by sulfate (51.0%) and organics (28.2%) with considerable acidity (average in situ pH = 0.95) and a characteristic bimodal particle size distribution with peaks at 200 and 570 nm of vacuum aerodynamic diameter (Dva). Source apportionment of organic aerosol yielded three characteristic aerosol fractions (hydrocarbon-like organic aerosol, semivolatile organic aerosol and low-volatile organic aerosol) with distinct temporal patterns and distributions in different particle size regions. The influence of air mass origin on species concentrations, particle size distributions and elemental ratios was investigated using backtrajectory analysis. Larger particle diameters, greater fractions of oxygenated organic aerosol and higher organic-to-carbon ratios were observed during coastal and continental air mass influence. Three major pollution events with elevated nonrefractory PM1 concentrations were observed in the sampling period, which were related to distinct meteorological and circulatory conditions. Accumulation and redistribution of local and regional pollutants were notable in a period of strong land-sea breeze over the Pearl River Delta region, with considerable photochemical activity and particle aging. Increased fractions of oxygenated organic aerosol were apparent in foggy conditions, illustrating the importance of aqueous phase oxidation processes in a cooler and more humid time period.

Lee, Berto P.; Li, Yong Jie; Yu, Jian Zhen; Louie, Peter K. K.; Chan, Chak K.

2013-08-01

243

Sources of optically active aerosol particles over the Amazon forest  

NASA Astrophysics Data System (ADS)

Size-fractionated ambient aerosol samples were collected at a pasture site and a primary rainforest site in the Brazilian Amazon Basin during two field campaigns (April-May and September-October 1999), as part of the European contribution to the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA-EUSTACH). The samples were analyzed for up to 19 trace elements by particle-induced X-ray emission analysis (PIXE), for equivalent black carbon (BC e) by a light reflectance technique and for mass concentration by gravimetric analysis. Additionally, we made continuous measurements of absorption and light scattering by aerosol particles. The vertical chemical composition gradients at the forest site have been discussed in a companion article (Journal of Geophysical Research-Atmospheres 108 (D18), 4591 (doi:4510.1029/2003JD003465)). In this article, we present the results of a source identification and quantitative apportionment study of the wet and dry season aerosols, including an apportionment of the measured scattering and absorption properties of the total aerosol in terms of the identified aerosol sources. Source apportionments (obtained from absolute principal component analysis) revealed that the wet and dry season aerosols contained the same three main components, but in different (absolute and relative) amounts: the wet season aerosol consisted mainly of a natural biogenic component, whereas pyrogenic aerosols dominated the dry season aerosol mass. The third component identified was soil dust, which was often internally mixed with the biomass-burning aerosol. All three components contributed significantly to light extinction during both seasons. At the pasture site, up to 47% of the light absorption was attributed to biogenic particles during the wet season, and up to 35% at the tower site during the wet-to-dry transition period. The results from the present study suggest that, in addition to pyrogenic particles, biogenic and soil dust aerosols must be taken into account when modeling the physical and optical properties of aerosols in forested regions such the Amazon Basin.

Guyon, Pascal; Graham, Bim; Roberts, Gregory C.; Mayol-Bracero, Olga L.; Maenhaut, Willy; Artaxo, Paulo; Andreae, Meinrat O.

244

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...

245

In Situ Electrostatic Separation of Ambient PM2.5 into Source-Specific Fractions During Collection in a FRM Sampler  

SciTech Connect

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.

Naresh Shah; Frank E. Huggins; Gerald P. Huffman

2006-07-31

246

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)

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 related to sea-ice formation timing and/or to changes in zonal wind intensity and atmospheric pathway; the mineralogical analysis of insoluble dust particles can allow the identification of continental sources, by comparison with soils collected in the potential source areas (PSAs); finally, the seasonal pattern of biogenic markers (such as methanesulphonic acid and non-sea-salt sulphate) can be linked to sea surface temperature, sea-ice cover and southern-hemisphere circulation modes (e.g., SOI, AAO or SAM and ACW). As regard as depositional and post-depositional processes, the analysis of chemical markers in aerosol, superficial snow and hoar crystals, sampled contemporaneously, will allow understanding the key factors (e.g., snow acidity, solar irradiation) affecting the preservation of components reversibly fixed in the snow layers (such as, for instance, methanesulphonic acid, nitrate and chloride). A summary of the major results from the chemical analysis of aerosol and snow collected at Dome C is here presented.

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

2010-05-01

247

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

Microsoft Academic Search

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

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

2005-01-01

248

Seasonal changes in Fe species and soluble Fe concentration in the atmosphere in the Northwest Pacific region based on the analysis of aerosols collected in Tsukuba, Japan  

NASA Astrophysics Data System (ADS)

Atmospheric iron (Fe) can be a significant source of nutrition for phytoplankton inhabiting remote oceans, which in turn has a large influence on the Earth's climate. The bioavailability of Fe in aerosols depends mainly on the fraction of soluble Fe (= [FeSol]/[FeTotal], where [FeSol] and [FeTotal] are the atmospheric concentrations of soluble and total Fe, respectively). However, the numerous factors affecting the soluble Fe fraction have not been fully understood. In this study, the Fe species, chemical composition, and soluble Fe concentrations in aerosols collected in Tsukuba, Japan were investigated over a year (nine samples from December 2002 to October 2003) to identify the factors affecting the amount of soluble Fe supplied into the ocean. The soluble Fe concentration in aerosols is correlated with those of sulfate and oxalate originated from anthropogenic sources, suggesting that soluble Fe is mainly derived from anthropogenic sources. Moreover, the soluble Fe concentration is also correlated with the enrichment factors of vanadium and nickel emitted by fossil fuel combustion. These results suggest that the degree of Fe dissolution is influenced by the magnitude of anthropogenic activity, such as fossil fuel combustion. X-ray absorption fine structure (XAFS) spectroscopy was performed in order to identify the Fe species in aerosols. Fitting of XAFS spectra coupled with micro X-ray fluorescence analysis (?-XRF) showed the main Fe species in aerosols in Tsukuba to be illite, ferrihydrite, hornblende, and Fe(III) sulfate. Moreover, the soluble Fe fraction in each sample measured by leaching experiments is closely correlated with the Fe(III) sulfate fraction determined by the XAFS spectrum fitting, suggesting that Fe(III) sulfate is the main soluble Fe in the ocean. Another possible factor that can control the amount of soluble Fe supplied into the ocean is the total Fe(III) concentration in the atmosphere, which was high in spring due to the high mineral dust concentrations during spring in East Asia. However, this factor does not contribute to the amount of soluble Fe to a larger degree than the effect of Fe speciation, or more strictly speaking the presence of Fe(III) sulfate. Therefore, based on these results, the most significant factor influencing the amount of soluble Fe in the North Pacific region is the concentration of anthropogenic Fe species such as Fe(III) sulfate that can be emitted from megacities in Eastern Asia.

Takahashi, Y.; Furukawa, T.; Kanai, Y.; Uematsu, M.; Zheng, G.; Marcus, M. A.

2013-08-01

249

The Role of Aerosol Composition in Arctic Cloud Formation  

NASA Astrophysics Data System (ADS)

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) and chemical (organic) component are required for an aerosol to be an effective ice nucleus.

Brooks, S. D.; Hiranuma, N.; Moffet, R.; Laskin, A.; Gilles, M. K.; Glen, A.

2010-12-01

250

Aerosol composition and source apportionment in Santiago de Chile  

NASA Astrophysics Data System (ADS)

Santiago de Chile, São Paulo and Mexico City are Latin American urban areas that suffer from heavy air pollution. In order to study air pollution in Santiago area, an aerosol source apportionment study was designed to measure ambient aerosol composition and size distribution for two downtown sampling sites in Santiago. The aerosol monitoring stations were operated in Gotuzo and Las Condes during July and August 1996. The study employed stacked filter units (SFU) for aerosol sampling, collecting fine mode aerosol (dp<2?m) and coarse mode aerosol (2Aerosol mass (PM10 mass of particles smaller than 10?m) and black carbon concentration were also measured. Particle-Induced X-ray Emission (PIXE) was used to measure the concentration of 22 trace elements at levels below 0.5ngm-3. Quantitative aerosol source apportionment was performed using Absolute Principal Factor Analysis (APFA). Very high aerosol concentrations were observed (up to 400?g/m3 PM10). The main aerosol particle sources in Santiago are resuspended soil dust and traffic emissions. Coarse particles account for 63% of PM10 aerosol in Goluzo and 53% in Las Condes. A major part of this component is resuspended soil dust. In the fine fraction, resuspended soil dust accounts for 15% of fine mass, and the aerosols associated with transportation activities account for a high 64% of the fine particle mass. Sulfate particle is an important component of the aerosol in Santiago, mainly originating from gas-to-particle conversion from SO2. In the Gotuzo site, sulfates are the highest aerosol component, accounting for 64.5% of fine mass. Direct traffic emissions are generally mixed with resuspended soil dust. It is difficult to separate the two components, because the soil dust in downtown Santiago is contaminated with Pb, Br, Cl, and other heavy metals that are also tracers for traffic emissions. Residual oil combustion is observed, with the presence of V, S and Ni. An aerosol components from industrial emissions is also present, with the presence of several heavy metals such as Zn, Cu and others. A factor with molybdenum, arsenic, copper and sulfur was observed frequently, and it results from emissions of copper smelters.

Artaxo, Paulo; Oyola, Pedro; Martinez, Roberto

1999-04-01

251

Fecal collection, ambient preservation, and DNA extraction for PCR amplification of bacterial and human markers from human feces.  

PubMed

Feces contain intestinal bacteria and exfoliated epithelial cells that may provide useful information concerning gastrointestinal tract health. Intestinal bacteria that synthesize or metabolize potential carcinogens and produce anti-tumorigenic products may have relevance to colorectal cancer, the second most common cause of cancer deaths in the USA. To facilitate epidemiological studies relating bacterial and epithelial cell DNA and RNA markers, preservative/extraction methods suitable for self-collection and shipping of fecal samples at room temperature were tested. Purification and PCR amplification of fecal DNA were compared after preservation of stool samples in RNAlater (R) or Paxgene (P), or after drying over silica gel (S) or on Whatman FTA cards (W). Comparisons were made to samples frozen in liquid nitrogen (N2). DNA purification methods included Whatman (accompanying FTA cards), Mo-Bio Fecal (MB), Qiagen Stool (QS), and others. Extraction methods were compared for amount of DNA extracted, DNA amplifiable in a real-time SYBR-Green quantitative PCR format, and the presence of PCR inhibitors. DNA can be extracted after room temperature storage for five days from W, R, S and P, and from N2 frozen samples. High amounts of total DNA and PCR-amplifiable Bacteroides spp. DNA (34%+/-9% of total DNA) with relatively little PCR inhibition were especially obtained with QS extraction applied to R preserved samples (method QS-R). DNA for human reduced folate carrier (SLC19A1) genomic sequence was also detected in 90% of the QS-R extracts. Thus, fecal DNA is well preserved by methods suitable for self-collection that may be useful in future molecular epidemiological studies of intestinal bacteria and human cancer markers. PMID:18162191

Nechvatal, Jordan M; Ram, Jeffrey L; Basson, Marc D; Namprachan, Phanramphoei; Niec, Stephanie R; Badsha, Kawsar Z; Matherly, Larry H; Majumdar, Adhip P N; Kato, Ikuko

2007-11-21

252

Seasonal variations of sulfate, carbonaceous species (black carbon and polycyclic aromatic hydrocarbons), and trace elements in fine atmospheric aerosols collected at subtropical islands in the East China Sea  

NASA Astrophysics Data System (ADS)

In order to characterize the outflow of pollution derived aerosols from the Asian Pacific rim to the North Pacific Ocean, seasonal variations of fine aerosol components (aerodynamic diameter <2 ?m) were collected at two islands (Amami Island and Miyako Island) that surround the East China Sea. Monthly averaged concentrations of non-sea-salt SO42- (nss.SO42-) and black carbon (BC) at Amami and Miyako showed relatively high values in winter to spring and low values in summer. The observed seasonal variation is basically determined by the northwesterly monsoon in winter to spring and southeasterly wind from the stationary North Pacific anticyclone in summer. The minimum concentration levels of nss.SO42- and BC in summer were almost 2-3 times that of the North Pacific background level. Trace metals in aerosols showed similar seasonal variations observed for nss.SO42- and BC. The concentrations of nss.SO42- and Sb were highly correlated; this is in contradiction with the results at stations established in Pacific Exploratory Mission-West ground monitoring sites. Polycyclic aromatic hydrocarbons (PAHs) also showed a pronounced maximum in winter and/or spring, with maximum concentrations comparable in magnitude to those in spring at Barrow, Alaska. Many of the low molecular weight species of PAHs had high correlation with BC, suggesting that they were either transported independently in a similar way or were transported attached to BC. Furthermore, the relative abundance of some PAH species in the present study and those found in deep-ocean surface sediments sampled in the middle Pacific Ocean are compared and discussed.

Kaneyasu, Naoki; Takada, Hideshige

2004-03-01

253

QUARTZ CONTENT AND ELEMENTAL COMPOSITION OF AEROSOLS FROM SELECTED SITES OF THE EPA (ENVIRONMENTAL PROTECTION AGENCY) INHALABLE PARTICULATE NETWORK  

EPA Science Inventory

The elemental composition and concentration of quartz in ambient aerosols collected on dichotomous filters from the EPA Inhalable Particulate Network (IPN) in 1980 have been determined by x-ray fluorescence and mass calibration methods of x-ray diffraction (XRD). Quartz concentra...

254

Optical Properties of Atmospheric Aerosol in Maritime Environments  

Microsoft Academic Search

Systematic characterization of aerosol over the oceans is needed to understand the aerosol effect on climate and on transport of pollutants between continents. Reported are the results of a comprehensive optical and physical characterization of ambient aerosol in five key island locations of the Aerosol Robotic Network (AERONET) of sun and sky radiometers, spanning over 2-5 yr. The results are

Alexander Smirnov; Brent N. Holben; Yoram J. Kaufman; Oleg Dubovik; Thomas F. Eck; Ilya Slutsker; Christophe Pietras; Rangasayi N. Halthore

2002-01-01

255

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

SciTech Connect

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.

Baustian, Kelly J.; Cziczo, Daniel J.; Wise, M. A.; Pratt, Kerri; Kulkarni, Gourihar R.; Hallar, Anna G.; Tolbert, Margaret A.

2012-03-30

256

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

NASA Astrophysics Data System (ADS)

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.

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

2012-03-01

257

The use of multi-band transmission data collected at Scripps pier in November 2006 for the investigation of aerosol characteristics  

NASA Astrophysics Data System (ADS)

The knowledge of the atmospheric aerosol characteristics is of great importance for the range performance of Infrared and Electro-Optical sensor systems. The composition, the concentration and the size distribution of aerosols determine their scattering behavior as function of wavelength and thus their attenuation of light beams. When studies are made on this attenuation, it is considered to be very useful to incorporate the spatial variation of the aerosol characteristics along the measurement path, such as found during a previous campaign, carried out over the San Diego Bay (August 2005). In a more recent experiment (November 2006) a trial was set-up at Scripps pier of the Institute of Oceanography near La Jolla (US-West Coast). This place is known for the high frequency of occurrence of hazy conditions, not only variable with location, but also in time. TNO did participate in this experiment with two Particle Measurement Systems (PMS), one on the shore and one at the end of the pier, a weather station and the Multi Spectral Radiometer Transmissometer (MSRT), used in previous trials. It was shown before, that the use of multi-band transmission data allows a more detailed analysis of the aerosol characteristics in the measurement path. The advantage of the MSRT concerns a larger measurement volume, thus providing a higher signal to noise (S/N) ratio and a shorter response time, compared to the in-situ PMS systems. A similar method, based on the spectral dependence of the scattering coefficient, has been used during the analysis of the data, collected in November 2006. In this paper representative data samples are presented, showing the variability of the transmission in each of the spectral bands. By using the weather data, a separation has been made between extinction by molecules and aerosols. A brief description is given of the retrieval method, just mentioned. The retrieved particle characteristics are compared to the data from the PMS systems, taking into account the fact, that part of the measurement path, having a length of 6.68 km, was grazing the shore-line. In general the particle density, as found by the PMS systems was less than the retrieved value, especially when the wind was from off-shore directions. At certain occasions, sinusoidal variations in the transmission level, with a period of about 5 minutes, were found, probably due to oscillatory motions of the air mass in the measurement path. It was found, that the value of the Junge exponent of the Particle Size Distribution (PSD) was rather frequently of the order of -3, showing that the concentration of bigger particles (> 3 ?m) compared to the smaller particles (< 0.5 ?m), was greater than the value, found in experiments at other locations. It is investigated how accurate the transmission levels of the IR bands can be predicted by using the retrieved PSD's and the absolute humidity, obtained from the weather data. Due to the low wind speed during the trial (< 4 m/s), it was not possible to find any particular effect from aerosols, potentially created in the surf zone at higher wind speeds.

de Jong, Arie N.; van Eijk, Alexander M. J.; Fritz, Peter J.; Cohen, Leo H.; Moerman, Marcel M.

2007-10-01

258

FORMATION OF PHOTOCHEMICAL AEROSOLS  

EPA Science Inventory

The objective was to develop a better understanding of smog aerosol formation with particular reference to haze in the Southern California area. This study combined laboratory work with ambient air studies. Counting of particles by light scattering was the principle physical tech...

259

EXPOSURES TO ACIDIC AEROSOLS  

EPA Science Inventory

Ambient monitoring of acid aerosol in four U.S. cities and in a rural region of southern Ontario clearly show distinct periods of strong acidity. easurements made in Kingston, TN, and Stuebenville, OH, resulted in 24-hr H+ ion concentrations exceeding 100 nmole/m3 more than 10 ti...

260

The effect of nonideal cascade impactor stage collection efficiency curves on the interpretation of the size of inhaler-generated aerosols.  

PubMed

Cascade impactors, operating on the principle of inertial size separation in (ideally) laminar flow, are used to determine aerodynamic particle size distributions (APSDs) of orally inhaled product (OIP) aerosols because aerodynamic diameter can be related to respiratory tract deposition. Each stage is assumed typically to be an ideal size fractionator. Thus, all particles larger than a certain size are considered collected and all finer particles are treated as penetrating to the next stage (a step function stage efficiency curve). In reality, the collection efficiency of a stage smoothly increases with particle size as an "S-shaped" curve, from approximately 0% to 100%. Consequently, in some cases substantial overlap occurs between neighboring stages. The potential for bias associated with the step-function assumption has been explored, taking full resolution and two-stage abbreviated forms of the Andersen eight-stage nonviable impactor (ACI) and the next-generation pharmaceutical impactor (NGI) as example apparatuses. The behavior of unimodal, log-normal APSDs typical of OIP-generated aerosols has been investigated, comparing known input values to calculated values of central tendency (mass median aerodynamic diameter) and spread (geometric standard deviation, GSD). These calculations show that the error introduced by the step change assumption is larger for the ACI than for the NGI. However, the error is sufficiently small to be inconsequential unless the APSD in nearly monodisperse (GSD ?1.2), a condition that is unlikely to occur with realistic OIPs. Account may need to be taken of this source of bias only for the most accurate work with abbreviated ACI systems. PMID:23508617

Roberts, D L; Mitchell, J P

2013-03-19

261

Aerosolization of fungi, (1-->3)-beta-D glucan, and endotoxin from flood-affected materials collected in New Orleans homes.  

PubMed

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)-beta-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 x 10(4)) to 2.6 x 10(5) CFU/m(2); total fungi ranged from 2.07 x 10(5) to 1.6 x 10(6) spores/m(2); (1-->3)-beta-D glucan and endotoxin were 2.0 x 10(3) - 2.9 x 10(4) ng/m(2) and 7.0 x 10(2) - 9.3 x 10(4) EU/m(2), respectively. The results showed that 5-15 min sampling is sufficient for detecting aerosolizable biocontaminants with the FSSST. Smaller particle size fractions (<1.0 and <1.8 microm) have levels of glucan and endotoxin comparable to larger (>1.8 microm) fractions, which raises additional exposure concerns. Vacuuming was found to overestimate inhalation exposure risks by a factor of approximately 10(2) for (1-->3)-beta-D glucan and by 10(3)-10(4) 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

Adhikari, Atin; Jung, Jaehee; Reponen, Tiina; Lewis, Jocelyn Suzanne; DeGrasse, Enjoli C; Grimsley, L Faye; Chew, Ginger L; Grinshpun, Sergey A

2009-02-08

262

Determination of free and total carbon in suspended air particulate matter collected on glass fiber filters  

Microsoft Academic Search

Free carbon is a visible, nuisance component of ambient air particulate matter and may also act as a catalyst in aerosol reactions. A method of determining both free and total carbon collected on glass fiber filters is described. Free carbon is determined by combustion of an aliquot of the exposed filter treated with nitric acid; total carbon is determined by

J. A. Pigmenta; George R. Wood

1980-01-01

263

Aerosol light scattering properties at Cape Grim, Tasmania, during the First Aerosol Characterization Experiment (ACE 1)  

Microsoft Academic Search

Large uncertainties remain in understanding the effects of ambient aerosols on climate. As part of the First Aerosol Characterization Experiment (ACE 1, November 15 to December 15, 1995), the total light scattering and backscattering coefficients by particles (cysp and CYbsp) were measured at Cape Grim, Tasmania. Such measurements were made to characterize aerosol radiative forcing relevant to climate change at

Christian M. Carrico; Mark J. Rood; John A. Ogren

1998-01-01

264

Non-ammonium reduced nitrogen species in atmospheric aerosol particles  

SciTech Connect

The traditional belief that ambient aerosol particles contain nitrogen predominantly in the form of inorganic ionic species such as NH/sub 4//sup +/ and NO/sub 3//sup -/ was challenged about 10 years ago by results from x-ray photoelectron spectroscopic analysis (ESCA) of California aerosol particles. A significant fraction (approx. 50%) of the reduced nitrogen was observed to have an oxidation state more reduced than ammonium, characteristic of organic nitrogen species. We have used a recently developed thermal evolved gas analysis method (NO/sub x/) in conjunction with ESCA to confirm the existence of these species in aerosol particles collected in both the United States and Europe. The agreement of EGA and ESCA analyses indicates that these species are found not only on the surface but also throughout the particles. 9 references, 6 figures.

Dod, R.L.; Gundel, L.A.; Benner, W.H.; Novakov, T.

1983-08-01

265

Using satellite aerosol retrievals to monitor surface particulate air quality  

NASA Astrophysics Data System (ADS)

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 Ångstrom 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 sunphotometers (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.

Levy, R. C.; Remer, L. A.; Kahn, R. A.; Chu, D.; Mattoo, S.; Holben, B. N.; Schafer, J. S.

2011-12-01

266

AMS Measurements in National Parks of Aerosol Mass, Size and Composition, Comparison with Filter Samples and Correlation with Particle Hygroscopicity and Optical Extinction Properties  

NASA Astrophysics Data System (ADS)

We report a comparison of results from aerosol studies at Great Smoky Mountain National Park (2006), Mt. Rainier National Park (2009) and Acadia National Park (2011), all class I visibility areas associated with IMPROVE (Interagency Monitoring of Protected Visual Environments) sites. This collaborative study was sponsored by the Electric Power Research Institute (EPRI) and was done with the cooperation of the National Park Service and the EPA. The atmospheric aerosol composition in these sites is influenced by a number of anthropogenic as well as biogenic sources, providing a rich environment for fundamental aerosol studies. The primary purpose of these studies was to add state-of-the-art aerosol instrumentation to the standard light extinction and aerosol measurements at the site, used to determine parameters for the IMPROVE light extinction reconstruction equation, adopted by the EPA to estimate light extinction from atmospheric aerosol concentrations and Rayleigh scattering. The combination of these diverse measurements also provides significant insight into fundamental aerosol properties such as aging and radiative forcing. New instrumentation included a quadrupole aerosol mass spectrometer (Aerodyne Q-AMS-Smoky Mountain Study), a high resolution aerosol time-of-flight mass spectrometer (Aerodyne HR-ToF-AMS - Mt. Rainier and Acadia studies) for real time measurements that directly address the relationship between sulfate, nitrate, and OC size and concentration, which is related to cloud and dry gas-to-particle conversion as air masses age during transport, the relationship between WSOC hygroscopic growth and oxygenated organic (OOA) composition, the OCM/OC ratio, and the chemical composition that determines the ambient hygroscopic state. The OCM/OC ratio and organic water uptake was addressed with high-volume and medium volume PM2.5 aerosol samples. Aerosols were collected daily on Teflon coated glass fiber filters (TGFF) in four high-volume PM2.5 samplers operated by DRI. These measurements provide the fraction of total OC that is water-soluble. The ambient hydration state was determined by the Don Collins group in the field with an ambient state TDMA (AS-TDMA). Aerosols are classified at ambient RH with an ambient diameter of Da. The sample is then dried to <20%, typically below the crystallization point of most aerosols. The sample is alternately left dry or humidified to 85-95% RH. The dried (path 1) or humidified (path 2) sample is then conditioned back to the original ambient RH, attaining a diameter Df. Continuous measurement of the hydration state over the diurnal cycle will be used to assess the validity of the assumption that hygroscopic growth follows the metastable branch of the ammonium sulfate growth curve.

Alexander, M.; Taylor, N. F.; Collins, D. R.; Kumar, N.; Allen, J.; Newburn, M.; Lowenthal, D. H.; Zielinska, B.

2011-12-01

267

Assessment of adsorption/solvent extraction with polyurethane foam and adsorption/thermal desorption with Tenax-GC for the collection and analysis of ambient organic vapors  

SciTech Connect

Two methods for the collection of ambient organic vapors at the ng/m/sup 3/ to ..mu..g/m/sup 3/ level were utilized in field sampling at a residential site in Portland, OR, during the winter and spring of 1983. The methods were adsorption/solvent extraction with polyurethane foam plugs (ASE/PUFP) and adsorption/thermal desorption with Tenax-GC cartridges (ATD/Tenax-GC). ASE/PUFP was used with a single sample flow rate in a single channel of the sampler. ATD/Tenax-GC was used with two different sample flow rates in two separate channels. Each method was found to be well suited to the analysis of compounds in a specific range of volatility. Some intermediate-volatility compounds were determined with all three sampling channels. The coefficients of variation for the three channels pooled over seven events were 9-36% for compounds in the range of volatility between acenaphthene and pyrene. The low sample volumes used with ATD/Tenax-GC for determinations at the ng/m/sup 3/ level make it an attractive method for many applications.

Ligocki, M.P.; Pankow, J.F.

1985-05-01

268

Characterization of nitrocatechols and related tracers in atmospheric biomass burning organic aerosol  

NASA Astrophysics Data System (ADS)

One of the largest primary sources of organic aerosols in the atmosphere is biomass burning (Laskin et al., 2009). The chemistry of compounds present in biomass burning aerosol (BBA) is diverse and directly dependent on the chemical composition of the burning material and the combustion conditions (Simoneit et al., 2002). A well-established tracer for primary BBA is levoglucosan (1,6-anhydro-?-anhydroglucose), which originates from the pyrolysis of cellulose or hemicellulose (Fine et al., 2002). Secondary BBA, which is formed after physical and chemical changes (aging) of the primary BBA in the atmosphere, contains more oxidized and polar compounds. An important class of compounds of secondary organic aerosols (SOA) is nitrocatechols, which are strong absorbers of UV and Vis light, and therefore, can affect the earth's radiative balance and climate. Recently, methyl nitrocatechols were proposed as suitable tracers for highly oxidized secondary BBA (Iinuma et al., 2010). These compounds are primarily formed from the photooxidation of m-cresol, that is emitted from biomass burning, in the presence of NOx. The objective of the present study was to characterize nitrocatechols in ambient aerosols using mass spectrometric and chromatographic techniques. Ambient aerosol samples were collected during a cold winter episode from an urban site in Maribor, Slovenia, where substantial residential wood burning for domestic purposes takes place. Emphasis was put on the development of a suitable LC-ESI-MS technique. In an initial step the chromatographic conditions were optimized for methyl nitrocatechols and related nitro-aromatic compounds using diode array UV/Vis detection. The optimized LC conditions were used for the development and validation of an LC-ESI-MS/MS method for identification and quantification of nitrocatechols in aerosol samples. LC/ESI-MS/MS data will be presented and interpreted for the nitro-aromatic compounds that are present in the collected ambient aerosols.

Grgic, I.; Kitanovski, Z.; Yasmeen, F.; Claeys, M.

2011-12-01

269

AEROSOL CHEMICAL CHARACTERISTION ON BOARD THE DOE G1 AIRCRAFT USING A PARTICLE INTO LIQUID SAMPLER DURING THE TEXAQS 2000 EXPERIMENT.  

SciTech Connect

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.

LEE,Y.N.; SONG,Z.; LIU,Y.; DAUM,P.; WEBER,R.; ORSINI,D.; LAULAINEN,N.; HUBBE,J.; MORRIS,V.

2001-01-13

270

Development of a capillary electrophoretic method for the analysis of low-molecular-weight amines from metal working fluid aerosols and ambient air.  

PubMed

A method for the determination of low-molecular-weight amines from indoor and ambient air was developed using a concentration device followed by CE coupled with indirect spectrophotometric and mass spectrometric detection that enables a reliable, rapid-response and easy-to-operate method. In indirect detection method, the selected amines were separated from interfering metal ions and amino alcohols present in the samples with an imidazole-based buffer with ethanol and EDTA as modifier. By replacing imidazole with ammonium, the final buffer was applicable for MS detection for the analytes with m/z higher than 50. A novel monolithic polymer material based on poly(methacrylate-acrylate) copolymer was developed for sampling short-chain amines from the gaseous phase. The selected analysis conditions were applied to quantify the selected short-chain amines with detection limits for the whole procedure determined between 1 and 2 microg/filter when 40 L air was sampled with 1 L/min velocity. Improved linearity and precision were obtained when the raw, time-scaled electropherogram data were transformed into mobility-scale applied for the determination of the performance characteristics of the methods. The applicability of the process of data transformation into the mobility scale was demonstrated by studying the matrix effect of water-miscible metal working fluid (stable water-oil emulsion) and of ambient air as real samples. CE-indirect UV and CE-MS, combined with the possibility of rapid air sampling, can be useful for the estimation of short-term exposure of the selected biogenic amines. PMID:16523461

Fekete, Agnes; Frommberger, Moritz; Ping, Guichen; Lahaniatis, Majlinda R; Lintelman, Jutta; Fekete, Jeno; Gebefugi, Istvan; Malik, Ashok Kumar; Kettrup, Antonius; Schmitt-Kopplin, Philippe

2006-03-01

271

Intercomparison and closure calculations using measurements of aerosol species and optical properties during the Yosemite Aerosol Characterization Study  

NASA Astrophysics Data System (ADS)

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 about 0.15 ?g/m3. Semi-continuous carbon concentrations did not compare favorably with 24-hour measurements. Fine mass closure calculations suggested that the factor for estimating organic mass from measurements of carbon was approximately 1.8. Furthermore, fine scattering closure calculations showed that the use of 4.0 m2/g for the fine organic mass scattering coefficient was an underestimate by at least 30% for periods with high organic mass concentrations.

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

272

Receptor modeling of the fine aerosol at a residential Los Angeles site  

NASA Astrophysics Data System (ADS)

Receptor modeling on ambient aerosol and air quality data collected at Duarte, CA (a residential site near Los Angeles), in 1983 and 1987-1988 was carried out. A significant change in the ambient concentrations of SO 42-, Al, Si, Mn, Fe, Pb, Br, volatile and organic carbon and fine particle (FP) mass took place from 1983 to 1987-1988. A drastic reduction (˜80%) of the ambient Pb and Br concentrations took place as the lead content and the usage of leaded gasoline decreased in the Los Angeles Basin during that period. A day-of-the-week analysis indicated that both crustal (Si, Ca, Fe) and transportation (Pb, CO, organic carbon and black carbon) related pollutants exhibit significantly different concentrations between weekdays and weekends of 1987-1988. this indicates that loadings of suspended soil dust are more affected by anthropogenic activities than meteorological patterns. In contrast, sulfate and volatile carbon concentrations seem to be insensitive to that cycle indicating that other sources/processes can be responsible for the ambient levels of these pollutants. Principal component analysis of aerosol and air quality data showed that the major contributions to the variance of the ambient aerosol loadings come from soil, motor vehicles and sulfates.

Ehrman, Sheryl H.; Pratsinis, Sotiris E.; Young, James R.

273

Comparison of Oxidative Properties, Light Absorbance, and Total and Elemental Mass Concentration of Ambient PM2.5 Collected at 20 European Sites  

PubMed Central

Objective It has been proposed that the redox activity of particles may represent a major determinant of their toxicity. We measured the in vitro ability of ambient fine particles [particulate matter with aerodynamic diameters ?2.5 ?m (PM2.5)] to form hydroxyl radicals (•OH) in an oxidant environment, as well as to deplete physiologic antioxidants (ascorbic acid, glutathione) in the naturally reducing environment of the respiratory tract lining fluid (RTLF). The objective was to examine how these toxicologically relevant measures were related to other PM characteristics, such as total and elemental mass concentration and light absorbance. Design Gravimetric PM2.5 samples (n = 716) collected over 1 year from 20 centers participating in the European Community Respiratory Health Survey were available. Light absorbance of these filters was measured with reflectometry. PM suspensions were recovered from filters by vortexing and sonication before dilution to a standard concentration. The oxidative activity of these particle suspensions was then assessed by measuring their ability to generate •OH in the presence of hydrogen peroxide, using electron spin resonance and 5,5-dimethyl-1-pyrroline-N-oxide as spin trap, or by establishing their capacity to deplete antioxidants from a synthetic model of the RTLF. Results and Conclusion PM oxidative activity varied significantly among European sampling sites. Correlations between oxidative activity and all other characteristics of PM were low, both within centers (temporal correlation) and across communities (annual mean). Thus, no single surrogate measure of PM redox activity could be identified. Because these novel measures are suggested to reflect crucial biologic mechanisms of PM, their use may be pertinent in epidemiologic studies. Therefore, it is important to define the appropriate methods to determine oxidative activity of PM.

Kunzli, Nino; Mudway, Ian S.; Gotschi, Thomas; Shi, Tingming; Kelly, Frank J.; Cook, Sarah; Burney, Peter; Forsberg, Bertil; Gauderman, James W.; Hazenkamp, Marianne E.; Heinrich, Joachim; Jarvis, Deborah; Norback, Dan; Payo-Losa, Felix; Poli, Albino; Sunyer, Jordi; Borm, Paul J.A.

2006-01-01

274

A temperature controlled AGI30 Impinger for sampling of bio-aerosols  

Microsoft Academic Search

AGI-30 Impingers are widely applied for efficient collection of bio-aerosols. However, these glass vessels are not protected against solar radiation and changing ambient temperature during sampling which may impair sampling efficiency by too high or low temperatures of the sampling liquid leading to early proliferation of micro-organisms or ice formation. In order to reduce such disadvantages an impinger holder was

A. C. Springorum; M. Clauß; J. Hartung

2011-01-01

275

Ambient air quality during wheat and rice crop stubble burning episodes in Patiala  

NASA Astrophysics Data System (ADS)

Open crop stubble burning events were observed in and around Patiala city, India. A ground level study was deliberated to analyze the contribution of wheat ( Triticum aestivum) and rice ( Oriza sativa) crop stubble burning practices on concentration levels of aerosol, SO 2 and NO 2 in ambient air at five different sites in and around Patiala city covering agricultural, commercial and residential areas. Aerosols were collected on GMF/A and QMF/A (Whatman) sheets for a 24 h period throughout the year in 2007. Simultaneously, sampling of SO 2 and NO 2 was conducted and results obtained during stubble burning periods were compared to the non-stubble burning periods. Results clearly pointed out a distinct increase in aerosol, SO 2 and NO 2 levels during the crop stubble burning periods.

Mittal, Susheel K.; Singh, Nirankar; Agarwal, Ravinder; Awasthi, Amit; Gupta, Prabhat K.

276

Global aerosol climatology from the MODIS satellite sensors  

Microsoft Academic Search

The recently released Collection 5 Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol products provide a consistent record of the Earth's aerosol system. Comparing with ground-based AERONET observations of aerosol optical depth (AOD) we find that Collection 5 MODIS aerosol products estimate AOD to within expected accuracy more than 60% of the time over ocean and more than 72% of the time

Lorraine A. Remer; Richard G. Kleidman; Robert C. Levy; Yoram J. Kaufman; Didier Tanré; Shana Mattoo; J. Vanderlei Martins; Charles Ichoku; Ilan Koren; Hongbin Yu; Brent N. Holben

2008-01-01

277

Oxidation enhancement of submicron organic aerosols by fog processing  

NASA Astrophysics Data System (ADS)

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 secondary organic aerosol formation.

Zhang, Q.; Ge, X.; Collier, S.; Setyan, A.; Xu, J.; Sun, Y.

2011-12-01

278

Aerosol composition and source apportionment in Santiago de Chile  

Microsoft Academic Search

Santiago de Chile, São Paulo and Mexico City are Latin American urban areas that suffer from heavy air pollution. In order to study air pollution in Santiago area, an aerosol source apportionment study was designed to measure ambient aerosol composition and size distribution for two downtown sampling sites in Santiago. The aerosol monitoring stations were operated in Gotuzo and Las

Paulo Artaxo; Pedro Oyola; Roberto Martinez

1999-01-01

279

Cloud Activating Properties of Aerosol Observed during CELTIC  

Microsoft Academic Search

Measurements of aerosol size distribution, chemical composition, and cloud condensation nuclei (CCN) concentration were performed during the Chemical Emission, Loss, Transformation, and Interactions with Canopies (CELTIC) field program at Duke Forest in North Carolina. A kinetic model of the cloud activation of ambient aerosol in the chamber of the CCN instrument was used to perform an aerosol-CCN closure study. This

Craig A. Stroud; Athanasios Nenes; Jose L. Jimenez; Peter F. Decarlo; J. Alex Huffman; Roelof Bruintjes; Eiko Nemitz; Alice E. Delia; Darin W. Toohey; Alex B. Guenther; Sreela Nandi

2007-01-01

280

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....

281

Size distribution, shape, and composition of mineral dust aerosols collected during the African Monsoon Multidisciplinary Analysis Special Observation Period 0: Dust and Biomass-Burning Experiment field campaign in Niger, January 2006  

Microsoft Academic Search

Dust samples were collected onboard the UK community BAe-146 research aircraft of the Facility for Airborne Atmospheric Measurements (FAAM) operated over Niger during the winter Special Observation Period of the African Monsoon Multidisciplinary Analysis project (AMMA SOP0\\/DABEX). Particle size, morphology, and composition were assessed using single-particle analysis by analytical scanning and transmission electron microscopy. The aerosol was found to be

Cédric Chou; Paola Formenti; Michel Maille; Patrick Ausset; Günter Helas; Mark Harrison; Simon Osborne

2008-01-01

282

Organosulfates as tracers for secondary organic aerosol (SOA) formation from 2-methyl-3-buten-2-ol (MBO) in the atmosphere.  

PubMed

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 (C(5)H(12)O(6)S, MW 200) formed and was substantially enhanced with elevated aerosol acidity. Ambient fine aerosol (PM(2.5)) 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 PM(2.5) 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

Zhang, Haofei; Worton, David R; Lewandowski, Michael; Ortega, John; Rubitschun, Caitlin L; Park, Jeong-Hoo; Kristensen, Kasper; Campuzano-Jost, Pedro; Day, Douglas A; Jimenez, Jose L; Jaoui, Mohammed; Offenberg, John H; Kleindienst, Tadeusz E; Gilman, Jessica; Kuster, William C; de Gouw, Joost; Park, Changhyoun; Schade, Gunnar W; Frossard, Amanda A; Russell, Lynn; Kaser, Lisa; Jud, Werner; Hansel, Armin; Cappellin, Luca; Karl, Thomas; Glasius, Marianne; Guenther, Alex; Goldstein, Allen H; Seinfeld, John H; Gold, Avram; Kamens, Richard M; Surratt, Jason D

2012-08-17

283

Organosulfates as Tracers for Secondary Organic Aerosol (SOA) Formation from 2-Methyl-3-Buten-2-ol (MBO) in the Atmosphere  

PubMed Central

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.

2012-01-01

284

Halogen Activation From Uptake of N2O5 on Chloride Containing Aerosol  

NASA Astrophysics Data System (ADS)

Nitrogen oxides play key roles in regional air quality, for example through the catalytic photochemical production of O3 involving daytime NOx (NO+NO2). At night, a large fraction of NOx is converted to the nitrate radical (NO3), formed by reaction of NO2 with O3, and dinitrogen pentoxide (N2O5), formed from subsequent reaction of NO3 with NO2. Heterogeneous uptake of N2O5 on chloride containing aerosol (such as sea salt) has been shown in laboratory studies to produce nitryl chloride (ClNO2); in ambient air, this could provide a source of Cl atoms, an important oxidant of VOCs. In this presentation, recent results from laboratory investigations of halogen activation by N2O5 on model aerosol substrates are presented. Yields of ClNO2 were found to be dependent on aerosol chloride content, in agreement with prior studies. Further, formation of molecular chlorine (Cl2) was observed at low aerosol pH. Potential implications for nocturnal halogen activation on ambient aerosol, using data collected during the Texas Air Quality Study - Gulf of Mexico Atmospheric Composition and Climate Study (TexAQS-GoMACCS) 2006, are discussed.

Osthoff, H. D.; Roberts, J. M.; Brown, S. S.; Quinn, P. K.; Bates, T. S.; Coffman, D.; Williams, E. J.; Lerner, B. M.; Kuster, W. C.; Gilman, J.; Dibb, J.; Ravishankara, A. R.

2008-12-01

285

Aerosolized avian influenza virus by laboratory manipulations  

PubMed Central

Background Avian H5N1 influenza viruses present a challenge in the laboratory environment, as they are difficult to collect from the air due to their small size and relatively low concentration. In an effort to generate effective methods of H5N1 air removal and ensure the safety of laboratory personnel, this study was designed to investigate the characteristics of aerosolized H5N1 produced by laboratory manipulations during research studies. Results Normal laboratory procedures used to process the influenza virus were carried out independently and the amount of virus polluting the on-site atmosphere was measured. In particular, zootomy, grinding, centrifugation, pipetting, magnetic stirring, egg inoculation, and experimental zoogenetic infection were performed. In addition, common accidents associated with each process were simulated, including breaking glass containers, syringe injection of influenza virus solution, and rupturing of centrifuge tubes. A micro-cluster sampling ambient air pollution collection device was used to collect air samples. The collected viruses were tested for activity by measuring their ability to induce hemagglutination with chicken red blood cells and to propagate in chicken embryos after direct inoculation, the latter being detected by reverse-transcription PCR and HA test. The results showed that the air samples from the normal centrifugal group and the negative-control group were negative, while all other groups were positive for H5N1. Conclusions Our findings suggest that there are numerous sources of aerosols in laboratory operations involving H5N1. Thus, laboratory personnel should be aware of the exposure risk that accompanies routine procedures involved in H5N1 processing and take proactive measures to prevent accidental infection and decrease the risk of virus aerosol leakage beyond the laboratory.

2012-01-01

286

Improved Method for the Evaluation of Real-Time Biological Aerosol Detection Technologies  

Microsoft Academic Search

There is a growing need to evaluate bioaerosol sensors under relevant operational conditions. New methods are needed that can mimic the temporal fluctuations of ambient aerosol backgrounds and present biological aerosol challenges in a way that simulates a plausible biological agent attack. The Dynamic Concentration Aerosol Generator was developed to address this need. The authors developed a series of aerosol

Shanna Ratnesar-Shumate; Michael L. Wagner; Charles Kerechanin; Gerad House; Kelly M. Brinkley; Christopher Bare; Neal A. Baker; Rachel Quizon; Jason Quizon; Alex Proescher; Eric Van Gieson; Joshua L. Santarpia

2011-01-01

287

Organic aerosols  

SciTech Connect

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.

Penner, J.E.

1994-01-01

288

Artificial Aerosols.  

National Technical Information Service (NTIS)

This volume contains the technical proceedings of the Workshop on Artificial Aerosols held in Vail, Colorado, June 19-20, 1979. The workshop reviewed the state-of-the-art of chemically, aerodynamically or pyrotechnically produced aerosols and identified f...

A. Deepak L. H. Ruhnke

1980-01-01

289

Time-resolved chemical characterization of aerosol particles down to 6 nm diameter in Stockton, California  

NASA Astrophysics Data System (ADS)

A versatile and compact sampling system has been developed to collect sequential time-resolved, dry aerosol particles down to 6 nm in diameter. Using the same technology as in the water-based condensation particle counters this system collects and deposits dry samples of ambient fine and ultrafine particles in 1mm spots. The size of the deposition area allows reducing collection times by increasing the concentration of particles in the 50-100 ?l volume of solvent used to extract the chemicals of interest.

Eiguren-Fernandez, Arantza; Lewis, Gregory; Spielman, Steven; Hering, Susanne

2013-05-01

290

Measurements at the Mt. Rainier IMPROVE Site of Aerosol Mass, Size and Composition and their Correlation with Particle Hygroscopicity  

NASA Astrophysics Data System (ADS)

We report preliminary results from an aerosol study at the Mt. Rainier (MORA) IMPROVE site, sponsored by EPRI. This collaboration involved researchers from the Environmental Molecular Sciences Laboratory (EMSL) at the Pacific Northwest National Laboratory, the Desert Research Institute (DRI) and Texas A&M University (TAMU), and was done with the cooperation of the National Park Service. The atmospheric aerosol composition at MORA is influenced by a number of anthropogenic and biogenic sources, providing a rich environment for fundamental aerosol studies. The primary purpose of this study was to use state-of-the-art aerosol instrumentation and measurement techniques to address issues related to the “IMPROVE light extinction reconstruction equation” adopted by the EPA to estimate light extinction from atmospheric aerosol concentrations. The combination of these diverse measurements also provides significant insight into fundamental aerosol properties such as aging and radiative forcing. New instrumentation included a high resolution aerosol time-of-flight mass spectrometer (Aerodyne HToF-AMS) for real-time, size resolved chemical measurements that directly address: 1) the IMPROVE assumption that sulfate, nitrate, and organic carbon (OC) concentrations vary directly with particle size as air masses age during transport, 2) the relationship between hygroscopic growth and oxygenated organic (OOA) composition, 3) the OCM (organic mass)/OC ratio, and 4) the relationship between chemical composition and the ambient hydration state. The ambient hydration state was measured in-situ by the TAMU group with an ambient state hygroscopic tandem differential mobility analyzer (AS-HTDMA)). This modification of the classic HTDMA records the changes in particle size at ambient RH from forcing sudden changes of hydration state. Aerosols were classified at ambient RH with a diameter of Da. The sample was dried to <20%, typically below the crystallization point of most aerosols and alternately returned to ambient RH (path 1) or humidified to 85-95% RH and then returned to ambient RH (path 2). The ambient hydration state is inferred from the ratio of the final diameter (Df) on paths 1 and 2 to Da. These results will be used to assess the validity of the IMPROVE assumption that hygroscopic growth follows the hysteresis branch of the ammonium sulfate growth curve and may also provide the basis for more sophisticated ambient hydration state models, representing a significant advance in the understanding of atmospheric aerosols. PM2.5 aerosol samples were collected daily by DRI for measurement of chemical composition, the water soluble organic (WSOC) fraction, the OCM/OC ratio, and separation of WSOC from inorganic constituents. Hygroscopic growth curves of isolated WSOC will be measured at TAMU by HTDMA. These results will be compared with aerosol composition (e.g., OOA/HOA ratio) measured in-situ with the HToF-AMS.

Alexander, M. L.; Newburn, M.; Lowenthal, D. H.; Zielinska, B.; Samy, S.; Collins, D. R.; Taylor, N.; Kumar, N.

2009-12-01

291

Mechanism for Production of Secondary Organic Aerosols and Their Representation in Atmospheric Models.  

National Technical Information Service (NTIS)

Table of Contents: Executive Summary; Introduction; 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 Representati...

J. H. Seinfeld R. C. Flagan

1999-01-01

292

Applying open-path Fourier transform infrared spectroscopy for measuring aerosols.  

PubMed

This paper examines the feasibility of using Open-Path Fourier Transform Infrared Spectroscopy (OP-FTIR) to measure aerosols. The extinction spectra of water, ammonium nitrate, and ammonium sulfate aerosols were first simulated with various particle size distributions (geometric mean ranged from 2 to 10 microm; geometric standard deviation ranged from 1.1 to 2.5) based on the Mie theory. An optimization procedure was developed to retrieve the geometric mean and standard deviation of the aerosols size distributions from the spectra, assuming that the complex refractive index is known. To test sensitivity, we also added 4%, 7%, and 10% noise levels to the spectra and compared the reconstruction results. In the experimental study, water aerosols were generated by a two-fluid nozzle inside a cylindrical chamber (3325 cm(3)). The extinction spectrum was collected with a modified FTIR and the size distribution information was retrieved following the same optimization procedure as the one used in the simulation study. The optimization procedure developed in this study reconstructed the size distribution reasonably well for particles with known refractive index (i.e. homogeneous or internally mixed aerosols). The results were robust with the added noise levels up to 10%, after removing inaccurate estimates with the use of the censoring criteria for reconstructed GSD < 1.3, reconstructed GM < 2.5 microm and GSD < 1.5, and reconstructed GM > 10 microm. With regard to externally mixed aerosols, the reconstructed results were sensitive to the noise within the measuring systems, although most ambient aerosols were internally mixed. The reconstructed size distribution in the chamber experiment had a GM of 3.85 microm and GSD of 1.70. The simulation results were applied to support this reconstruction result. We conclude that OP-FTIR can be used to measure aerosols and screen for the right region for a more detailed aerosol measurement campaign. PMID:17616885

Wu, Chang-Fu; Chen, Yen-Ling; Chen, Chih-Chieh; Yang, Tzu-Ting; Chang, Pao-Erh

2007-07-01

293

Sampling, characterization, and remote sensing of aerosols formed in the atmospheric hydrolysis of uranium hexafluoride  

SciTech Connect

When gaseous uranium hexafluoride (UF/sub 6/) is released into the atmosphere, it rapidly reacts with ambient moisture to form an aerosol of uranyl fluoride (UO/sub 2/F/sub 2/) and hydrogen fluoride (HF). As part of our Safety Analysis program, we have performed several experimental releases of HF/sub 6/ in contained volumes in order to investigate techniques for sampling and characterizing the aerosol materials. The aggregate particle morphology and size distribution have been found to be dependent upon several conditions, including the temperature of the UF/sub 6/ at the time of its release, the relative humidity of the air into which it is released, and the elapsed time after the release. Aerosol composition and settling rate have been investigated using stationary samplers for the separate collection of UO/sub 2/F/sub 2/ and HF and via laser spectroscopic remote sensing (Mie scatter and infrared spectroscopy). 25 refs., 16 figs., 5 tabs.

Bostick, W.D.; McCulla, W.H.; Pickrell, P.W.

1984-05-01

294

Sampling, characterization, and remote sensing of aerosols formed in the atmospheric hydrolysis of uranium hexafluoride  

SciTech Connect

When gaseous uranium hexafluoride (UF/sub 6/) is released into the atmosphere, it rapidly reacts with ambient moisture to form an aerosol of uranyl fluoride (UO/sub 2/F/sub 2/) and hydrogen fluoride (HF). As part of their Safety Analysis program, the authors have performed several experimental releases of UF/sub 6/ in contained volumes in order to investigate techniques for sampling and characterizing the aerosol materials. The aggregate particle morphology and size appear to be dependent upon several conditions, including the relative humidity of the air into which it is released, and the elapsed time after the release. Aerosol composition and settling rate have been investigated using stationary samplers for the separate collection of UO/sub 2/F/sub 2/ and HF, and via laser spectroscopic remote sensing (Mie scatter and infrared spectroscopy).

Bostick, W.D.; McCulla, W.H.; Pickrell, P.W.

1985-01-01

295

Aerosol size distribution and seasonal variation in an urban area of an industrial city in central India.  

PubMed

To study the size distribution and seasonal variations of atmospheric aerosols, size-segregated aerosol samples were collected from July 2009 to June 2010 using the nine-stage cascade impactor aerosol sampler in Durg City, India. The aerosol particles exhibited bimodal size distribution on mass concentration with a peak at 2.5-4.4 ?m size ranges in the coarse mode and 2.1-2.5 ?m size ranges in the fine mode. The aerosol mass and size distribution during monsoon were found unimodal distribution with a peak in the coarse mode, while they showed trimodal distributions during winter with all three peaks appearing in the fine mode. The annual mean concentration of PM(10) aerosol was found to be 253.5 ± 99.4 ?g/m(3), which is four times higher as compared to the annual guideline of National Ambient Air Quality Standards (NAAQS) of India prescribed by the Central Pollution Control Board (CPCB), India. The highest aerosol mass concentrations were found during winter due to enormous biomass burning, while the lowest concentrations were observed during monsoon due to heavy rainfall. Air quality index values calculated in this study showed that 35% of the days were unhealthy for sensitive people, 35% were unhealthy or very unhealthy, while 3.3% were found as hazardous in Durg City, India. PMID:22990766

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

2012-09-19

296

Important source of marine secondary organic aerosol from biogenic amines.  

PubMed

Relevant concentrations of dimethyl- and diethylammonium salts (DMA+ and DEA+) were measured in submicrometer marine aerosol collected over the North Atlantic during periods of high biological activity (HBA) in clean air masses (median concentration (minimum-maximum)=26(6-56) ng m(-3)). Much lower concentrations were measured during periods of low biological activity (LBA): 1 (<0.4-20) ng m(-3) and when polluted air masses were advected to the sampling site: 2 (<0.2-24) ng m(-3). DMA+ and DEA+ are the most abundantorganic species, second only to MSA, detected in fine marine particles representing on average 11% of the secondary organic aerosol (SOA) fraction and a dominant part (35% on average) of the water-soluble organic nitrogen (WSON). Several observations support the hypothesis that DMA+ and DEA+ have a biogenic oceanic source and are produced through the reaction of gaseous amines with sulfuric acid or acidic sulfates. Moreover, the water-soluble fraction of nascent marine aerosol particles produced by bubble-bursting experiments carried out in parallel to ambient aerosol sampling over the open ocean showed WSON, DMA+, and DEA+ concentrations always below the detection limit, thus excluding an important primary sea spray source. PMID:19174880

Facchini, Maria Cristina; Decesari, Stefano; Rinaldi, Matteo; Carbone, Claudio; Finessi, Emanuela; Mircea, Mihaela; Fuzzi, Sandro; Moretti, Fabio; Tagliavini, Emilio; Ceburnis, Darius; O'Dowd, Colin D

2008-12-15

297

Ambient Intelligence in Urban Environments  

Microsoft Academic Search

This paper reports advances achieved within a project called LAICA (Laboratorio di Ambient Intelligence per una Città Amica) on Ambient Intelligence in urban environments. The overall LAICA architecture is described and the unified operative centre developed by Regulus SpA (partner of the project) to collect and correlate data from different sensors and prototypes is depicted. Moreover, the paper describes the

Rita Cucchiara; Andrea Prati; Cesare Osti; Stefano Pavani

298

Carbonaceous aerosols from prescribed burning of a boreal forest ecosystem  

SciTech Connect

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).

Mazurek, M.A. (Brookhaven National Lab., Upton, NY (United States)); Cofer, W.R. III; Levine, J.S. (National Aeronautics and Space Administration, Hampton, VA (United States). Langley Research Center)

1990-10-01

299

Indian aerosols: present status.  

PubMed

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

Mitra, A P; Sharma, C

2002-12-01

300

Cough-generated aerosols of Pseudomonas aeruginosa and other Gram-negative bacteria from patients with cystic fibrosis  

PubMed Central

Background: Pseudomonas aeruginosa is the most common bacterial pathogen in patients with cystic fibrosis (CF). Current infection control guidelines aim to prevent transmission via contact and respiratory droplet routes and do not consider the possibility of airborne transmission. It was hypothesised that subjects with CF produce viable respirable bacterial aerosols with coughing. Methods: A cross-sectional study was undertaken of 15 children and 13 adults with CF, 26 chronically infected with P aeruginosa. A cough aerosol sampling system enabled fractioning of respiratory particles of different sizes and culture of viable Gram-negative non-fermentative bacteria. Cough aerosols were collected during 5 min of voluntary coughing and during a sputum induction procedure when tolerated. Standardised quantitative culture and genotyping techniques were used. Results: P aeruginosa was isolated in cough aerosols of 25 subjects (89%), 22 of whom produced sputum samples. P aeruginosa from sputum and paired cough aerosols were indistinguishable by molecular typing. In four cases the same genotype was isolated from ambient room air. Approximately 70% of viable aerosols collected during voluntary coughing were of particles ?3.3 ?m aerodynamic diameter. P aeruginosa, Burkholderia cenocepacia, Stenotrophomonas maltophilia and Achromobacter xylosoxidans were cultivated from respiratory particles in this size range. Positive room air samples were associated with high total counts in cough aerosols (p?=?0.003). The magnitude of cough aerosols was associated with higher forced expiratory volume in 1 s (r?=?0.45, p?=?0.02) and higher quantitative sputum culture results (r?=?0.58, p?=?0.008). Conclusion: During coughing, patients with CF produce viable aerosols of P aeruginosa and other Gram-negative bacteria of respirable size range, suggesting the potential for airborne transmission.

Wainwright, C E; France, M W; O'Rourke, P; Anuj, S; Kidd, T J; Nissen, M D; Sloots, T P; Coulter, C; Ristovski, Z; Hargreaves, M; Rose, B R; Harbour, C; Bell, S C; Fennelly, K P

2009-01-01

301

Measuring the charge and size distribution of charged aerosol particles inside PMSE and NLC  

Microsoft Academic Search

During the MIDAS\\/MacWave 2002 rocket campaign charged aerosol probes launched aboard MIDAS payloads detected positively and negatively charged aerosol particles. Two aerosol probes were used on each MIDAS payload. One probe was a collection surface shielded by a magnetic field that prevented electron collection, allowing unambiguous identification of negative aerosol particles. The other probe was a collection surface shielded by

Byron Smiley; Markus Rapp; Tom Blix; Scott Robertson; Mihaly Horányi; Ralph Latteck

2003-01-01

302

Ambient sound budgets  

NASA Astrophysics Data System (ADS)

The underwater ambient sound field contains a lot of information about geophysical, biological and anthropogenic activities in the ocean. Identification and quantification of these signals will complement more traditional measurements collected on future ocean observatories, including systems cabled to shore and remote mooring arrays. Long-term ambient sound measurements using a low duty cycle recorder are reported from remote deep ocean moorings, coastal shelf moorings, inland waterways and even a deep, quiet fresh water lake. Identifiable geophysical signals include accurate measurements of wind speed and rainfall over a wide range of wind speeds and rainfall rates. The character and temporal patterns of biological activity, shipping and recreational boating are monitored. The overall ambient sound budgets will be reported for these different environments. Acoustic monitoring is available from sub-surface moorings, remote locations and under severe weather conditions where and when other ocean instrumentation is likely to fail. [Work supported by ONR Ocean Acoustics.

Nystuen, Jeffrey A.; Howe, Bruce M.

2005-04-01

303

Aerosol Inhaler.  

National Technical Information Service (NTIS)

The invention is an item of medical equipment, an aerosol inhaler used for treatment of respiratory tracts. Familiar aerosol inhalers consist of a housing with a water bath, an inlet fitting, a nozzle, a container with the medicinal solution to be sprayed...

A. S. Perelmutr M. L. Talalai S. A. Glukov

1973-01-01

304

Daily and hourly chemical impact of springtime transboundary aerosols on Japanese air quality  

NASA Astrophysics Data System (ADS)

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.

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

305

Daily and hourly chemical impact of springtime transboundary aerosols on Japanese air quality  

NASA Astrophysics Data System (ADS)

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.

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

306

Aerosol Microtops II sunphotometer observations over Ukraine  

NASA Astrophysics Data System (ADS)

Atmospheric aerosols and their impact on climate study are based on measurements by networks of ground-based instruments, satellite sensors, and measurements on portable sunphotometers. This paper presents the preliminary aerosol characteristics obtained during 2009-2012 using portable multi-wavelength Microtops II sunphotometer. Measurements were collected at different Ukraine sites in Kyiv, Odesa, Lugansk, Rivne, Chornobyl regions. The main aerosol characteristics, namely aerosol optical thickness (AOT) and Angstroem exponent, have been retrieved and analyzed. Aerosol data processing, filtering and calibration techniques are discussed in the paper.

Bovchaliuk, V.; Bovchaliuk, A.; Milinevsky, G.; Danylevsky, V.; Sosonkin, M.; Goloub, Ph.

2013-08-01

307

A new source of oxygenated organic aerosol and oligomers  

NASA Astrophysics Data System (ADS)

A large oxygenated organic uptake to aerosols was observed when exposing ambient urban air to inorganic acidic and non-acidic sulfate seed aerosol. For non-acidic seed aerosol the uptake was attributed to the direct dissolution of primary vehicle exhaust gases into the aqueous aerosol fraction, and was correlated to the initial seed sulphate mass. The uptake of primary oxygenated organic gases to aerosols in this study represents a significant amount of organic aerosol (OA) that may be considered primary when compared to that reported for primary organic aerosol (POA), but is considerably more oxygenated (O : C ~ 0.3) than traditional POA. Consequently, a fraction of measured ambient oxygenated OA, which correlates with secondary sulphate, may in fact be of a primary, rather than secondary source. These results represent a new source of oxygenated OA on neutral aerosol and imply that the uptake of primary organic gases will occur in the ambient atmosphere, under dilute conditions, and in the presence of pre-existing SO4 aerosols which contain water. Conversely, under acidic seed aerosol conditions, oligomer formation was observed with the uptake of organics being enhanced by a factor of three or more compared to neutral aerosols, and in less than 2 min, representing an additional source of SOA to the atmosphere. This resulted in a trajectory in Van Krevelen space towards higher O : C (slope ~ -1.5), despite a lack of continual gas-phase oxidation in this closed system. The results demonstrate that high molecular weight species will form on acidic aerosols at the ambient level and mixture of organic gases, but are otherwise unaffected by subsequent aerosol neutralization, and that aerosol acidity will affect the organic O : C via aerosol-phase reactions. These two processes, forming oxygenated POA under neutral conditions and SOA under acidic conditions can contribute to the total ambient OA mass and the evolution of ambient aerosol O : C ratios. This may be important for properly representing organic aerosol O : C ratios in air quality and climate models.

Liggio, J.; Li, S.-M.

2013-03-01

308

Near real time vapor detection and enhancement using aerosol adsorption  

DOEpatents

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.

Novick, Vincent J. (Downers Grove, IL); Johnson, Stanley A. (Countryside, IL)

1999-01-01

309

Near real time vapor detection and enhancement using aerosol adsorption  

DOEpatents

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.

Novick, Vincent J.; Johnson, Stanley A.

1997-12-01

310

Individual particle analysis of aerosols collected under haze and non-haze conditions at a high-elevation mountain site in the North China plain  

NASA Astrophysics Data System (ADS)

The North China plain is a region with megacities and huge populations. Aerosols over the highly polluted area have a significant impact on the regional and global climate. In order to investigate the physical and chemical characteristics of aerosol particles in elevated layers there, observations were carried out at the summit of Mt. Tai (1534 m a.s.l.) from 19 to 28 April, 2010, when the air masses were advected from the east (phase-I: 19-21 April), from the south (phase-II: 22-25 April), and from the northwest (phase-III: 26-28 April). Individual aerosol particles were identified with transmission electron microscopy (TEM), new particle formation (NPF) and growth events were monitored by a wide-range particle spectrometer, and ion concentrations in PM2.5 were analyzed. During phase-I and phase-II, haze layers caused by anthropogenic pollution were observed, and a high percentage of particles were sulfur-rich (47-49%). In phase-III, the haze disappeared due to the intrusion of cold air from the northwest, and mineral dust particles from deserts were dominant (43%). NPF followed by particle growth during daytime was more pronounced on hazy than on clear days. Particle growth during daytime resulted in an increase of particle geometric mean diameter from 10-22 nm in the morning to 56-96 nm in the evening. TEM analysis suggests that sulfuric acid and secondary organic compounds should be important factors for particle nucleation and growth. However, the presence of fine anthropogenic particles (e.g., soot, metal, and fly ash) embedded within S-rich particles indicates that they could weaken NPF and enhance particle growth through condensation and coagulation. Abundant mineral particles in phase-III likely suppressed the NPF processes because they supplied sufficient area on which acidic gases or acids condensed.

Li, W. J.; Zhang, D. Z.; Shao, L. Y.; Zhou, S. Z.; Wang, W. X.

2011-11-01

311

Acid aerosols in the Pittsburgh Metropolitan area  

NASA Astrophysics Data System (ADS)

This article presents data on ambient concentrations of selected acidic aerosols at four existing monitoring sites in the Pittsburgh PA metropolitan area. The data were collected by staff of the Allegheny County Health Department, Division of Air Quality during the summer and fall of 1993. The sampling protocol was focused on obtaining 24 h-average ammonia, ammonium, acidic sulfates, and particle strong acids data on a 2 to 3 day cycle. The data were obtained using Harvard University School of Public Health's "Short-HEADS" annular denuder sampling train. The Pittsburgh area is of interest because it is downwind of a major regional source of sulfur and nitrogen emissions from coal-burning power plants: the Ohio River Valley. The data presented here indicate that ground-level concentrations of acidic aerosols in Pittsburgh are highly correlated spatially and that many pollutants are higher on days when ground-level wind direction vectors indicate that wind is coming from the southwest rather than from the Pittsburgh source area itself. The monitoring site that is most upwind of the Pittsburgh source area - South Fayette - has particle strong acid levels about twice those of sites closer in to the Pittsburgh central business district.

McCurdy, Thomas; Zelenka, Michael P.; Lawrence, Philip M.; Houston, Robert M.; Burton, Robert

312

Carbonaceous aerosols in Norwegian urban areas  

Microsoft Academic Search

Little is known regarding levels and source strength of carbonaceous aerosols in Scandinavia. In the present study, ambient aerosol (PM10 and PM2.5) concentrations of elemental carbon (EC), organic carbon (OC), water-insoluble organic carbon (WINSOC), and water-soluble organic carbon (WSOC) are reported for a curbside site, an urban background site, and a suburban site in Norway in order to investigate their

K. E. Yttri; C. Dye; O.-A. Braathen; D. Simpson; E. Steinnes

2009-01-01

313

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

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.

Sterner, R.T.; Shumake, S.A.; Johns, B.E.; Thompson, R.D.

1987-12-01

314

Sea Salt Aerosol Collector for Marine Turbine Inlet Air Ducts.  

National Technical Information Service (NTIS)

A new design for a sea salt aerosol collector is described. It is specifically intended to collect aerosol samples from marine gas turbine air inlet ducts. Samples are deposited on 13 mm diameter filter membranes suitable for chloride determination using ...

J. B. Hoover T. B. Warner

1983-01-01

315

Composition of Size-Fractionated Aerosol in Charleston, West Virginia.  

National Technical Information Service (NTIS)

Atmospheric aerosols were collected during a 21 day period in late summer of 1976 in Charleston, West Virginia, using five dichotomous virtual impactor samplers simultaneously. The resulting coarse and fine aerosol were analyzed with a variety of physical...

C. W. Lewis E. S. Macias

1979-01-01

316

Carbonaceous aerosols in Norwegian urban areas  

NASA Astrophysics Data System (ADS)

Little is known regarding levels and source strength of carbonaceous aerosols in Scandinavia. In the present study, ambient aerosol (PM10 and PM2.5) concentrations of elemental carbon (EC), organic carbon (OC), water-insoluble organic carbon (WINSOC), and water-soluble organic carbon (WSOC) are reported for a curbside site, an urban background site, and a suburban site in Norway in order to investigate their spatial and seasonal variations. Aerosol filter samples were collected using tandem filter sampling to correct for the positive sampling artefact introduced by volatile and semivolatile OC. Analyses were performed using the thermal optical transmission (TOT) instrument from Sunset Lab Inc., which corrects for charring during analysis. Finally, we estimated the relative contribution of OC from wood burning based on the samples content of levoglucosan. Levels of EC varied by more than one order of magnitude between sites, likely due to the higher impact of vehicular traffic at the curbside and the urban background sites. In winter, the level of particulate organic carbon (OCp) at the suburban site was equal to (for PM10) or even higher (for PM2.5) than the levels observed at the curbside and the urban background sites. This finding was attributed to the impact of residential wood burning at the suburban site in winter, which was confirmed by a high mean concentration of levoglucosan (407 ng m-3). This finding indicates that exposure to primary combustion derived OCp could be equally high in residential areas as in a city center. It is demonstrated that OCp from wood burning (OCwood) accounted for almost all OCp at the suburban site in winter, allowing a new estimate of the ratio TCp/levoglucosan for both PM10 and PM2.5. Particulate carbonaceous material (PCM=Organic matter+Elemental matter) accounted for 46-83% of PM10 at the sites studied, thus being the major fraction.

Yttri, K. E.; Dye, C.; Braathen, O.-A.; Simpson, D.; Steinnes, E.

2009-03-01

317

Apparatus for sampling and characterizing aerosols  

DOEpatents

Apparatus for sampling and characterizing aerosols having a wide particle size range at relatively low velocities may comprise a chamber having an inlet and an outlet, the chamber including: a plurality of vertically stacked, successive particle collection stages; each collection stage includes a separator plate and a channel guide mounted transverse to the separator plate, defining a labyrinthine flow path across the collection stage. An opening in each separator plate provides a path for the aerosols from one collection stage t

Dunn, P.F.; Herceg, J.E.; Klocksieben, R.H.

1984-04-11

318

Mesospheric aerosol sampling spectrometer  

NASA Astrophysics Data System (ADS)

. 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.

Knappmiller, Scott; Robertson, Scott; Sternovsky, Zoltan; Horanyi, Mihaly; Kohnert, Rick

319

Asian aerosol transport to Alaska during ACE-Asia  

Microsoft Academic Search

Aerosols were collected at Adak Island, Alaska, one of the southernmost Aleutian Islands, and the Poker Flat Research Range, 30 km northeast of Fairbanks, Alaska, during the 2001 Aerosol Characterization Experiment-Asia Intensive Field Phase (March through April 2001). The size- and time-resolved aerosols were collected using three-stage DRUM aerosol sampling systems and analyzed for 42 elements between sodium and lead

Catherine F. Cahill

2003-01-01

320

Aerosol Optical Properties of Smoke from the Las Conchas Wildfire, Los Alamos, NM  

NASA Astrophysics Data System (ADS)

The Las Conchas wildfire in Northern New Mexico started on June, 26 2011 and spread rapidly, eventually burning an area of 634 km2 (245 mi2). Due to the close proximity to the fire, the Los Alamos National Laboratory (LANL) was shut down and the town evacuated for several days. Immediately after LANL reopened (7/6/2011) the Earth and Environmental Sciences Division (EES-14) attained unique measurements of the smoke by sampling the ambient air. Three Integrated Photoacoustic/Nephelometer Spectrometers (DMT Inc.) were set up to measure aerosol light absorption and scattering coefficients. A University of Northwest Switzerland thermodenuder was used to remove compounds that are volatile at temperatures up to 200C. The aerosol's optical properties were measured before and after denuding the sample at 405nm (blue), 532nm (green), 781nm (red), and for non-denuded particles also at 375nm (ultraviolet). The aerosol size distributions were measured after the denuder with a Laser Aerosol Spectrometer (LAS, TSI Inc.) and black carbon was measured with a Single Particle Soot Photometer (SP2, DMT Inc.). Additionally, ambient measurements of Total Particulate Matter (PM2.5 and PM10) were collected continuously at the LANL air monitoring stations. These measurements are used in conjunction with numerical simulations to determine the bulk optical properties of the aerosol. Aerosols in wildfire smoke are composed of organic and black carbon (soot) particles that are formed during wood combustion and pyrolysis. The optical properties of the smoke particles are complex and lead to large uncertainties in assessing the global climate. During the measurement period, the Las Conchas fire provided very high particle concentrations (up to 200 ?g/m3) that were exploited to investigate their optical properties. By heating the particles to temperatures ranging from 75 to 200C in the denuder, volatile organics were removed and the optical properties of the remaining particles were measured. Denuding of the aerosols, removed the outer organic coatings leaving behind the inner core of black carbon (soot) and any compounds that did not volatize completely. By simultaneously measuring the optical properties of the non-denuded as well as the denuded aerosol, we can study how the coatings affect the optical properties. The absorption coefficient measurements showed that coatings can cause an increase or decrease in absorption. The photoacoustic measurements were also combined with SP2 measurements to gain a mechanistic understanding of the effect of composition on the mass light absorption cross-sections of carbonaceous aerosols emitted by fires.

Gorkowski, K.; Dubey, M. K.; Flowers, B. A.; Aiken, A. C.; Klein, B. Z.; Mazzoleni, C.; Sharma, N.; China`, S.

2011-12-01

321

Individual particle analysis of aerosols collected under haze and non-haze conditions at a high-elevation mountain site in the North China plain  

NASA Astrophysics Data System (ADS)

The North China plain is a region with megacities and huge populations. Aerosols over the highly polluted area have a significant impact on a regional and global climate. In order to investigate the physical and chemical characteristics of aerosol particles in elevated layers there, observations were carried out at the summit of Mt. Tai (1534 m a.s.l) from 19 to 28 April 2010, when the air masses were advected from the east (phase-I: 19-21 April), from the south (phase-II: 22-25 April), and from the northwest (phase-III: 26-28 April). Individual aerosol particles were identified with transmission electron microscopy (TEM), new particle formation (NPF) and growth events were monitored by a wide-range particle spectrometer, and ion concentrations in PM2.5 were analyzed. During phase-I and phase-II, haze layers caused by anthropogenic pollution were observed, and a major number of particles were sulfur-rich (47-49 %). In phase-III, haze disappeared due to the intrusion of cold air from the northwest, and mineral dust particles from deserts were predominant (43 %). NPF followed by particle growth during daytime was more pronounced at upper levels of the haze layers than clear days. Particle growth during daytime resulted in an increase of particle geometric mean diameter from 10-22 nm in the morning to 56-96 nm in the evening. TEM analysis suggests that sulfuric acid and secondary organic compounds should be important factors for particle nucleation and growth. Moreover, the presence of ultrafine and fine anthropogenic particles (e.g., soot, metal, and fly ash) embedded within S-rich particles may indicate their influences on particle nucleation through condensation and enhancement of particle growth through coagulation. Each fine refractory particle can enlarge the sulfate particles by 10-20 nm. Abundant mineral particles in phase-III likely suppressed the NPF processes because a high number of crustal mineral particles in the free troposphere supplied an important surface on which acidic gases or acids condensed.

Li, W. J.; Zhang, D. Z.; Shao, L. Y.; Zhou, S. Z.; Wang, W. X.

2011-08-01

322

Airborne measurements of aerosol light extinction enhancement in California  

Microsoft Academic Search

Direct aerosol-radiation interactions are recognised to be among the most significant forcers of climate change. They are also among the most uncertain. One factor contributing to this uncertainty is the level of enhanced extinction that arises as hygroscopic aerosols change size in response to changes in ambient relative humidity (RH). Recent laboratory and field studies have sought to generalise the

J. M. Langridge; D. A. Lack; M. Richardson; D. C. Law; C. A. Brock; R. Bahreini; A. M. Middlebrook; D. M. Murphy

2010-01-01

323

Detection and quantification of levoglucosan in atmospheric aerosols: a review.  

PubMed

Levoglucosan is a tracer for biomass burning sources in atmospheric aerosol particles. Therefore, much effort has been recently put into developing methods for its quantification. This review describes and compares both established and emerging analytical methods for levoglucosan quantification in ambient aerosol samples, with the special needs of the environmental analytical chemist in mind. PMID:16317539

Schkolnik, Gal; Rudich, Yinon

2005-11-30

324

A Study on the Physical and Chemical Properties of Stratospheric Aerosols. Ph.D. Thesis  

Microsoft Academic Search

The physical and chemical properties of stratospheric aerosols under background and perturbed conditions are discussed. First, a multicomponent aerosol physical chemistry model was developed to study the composition and reactivity of stratospheric aerosols. The compositions are predicted from an equilibrium assumption between the condensed- and gas-phases, and they are calculated as a function of ambient temperature, relative humidity, and the

Tabazadeh

1994-01-01

325

Overview of submicron aerosol characterization in China using an Aerodyne high-resolution aerosol mass spectrometer  

NASA Astrophysics Data System (ADS)

China is one of the most rapidly developing countries in the world, but in the meantime it is suffering from severe air pollution due to heavy industrial/metropolitan emissions. Most previous aerosol studies in China were based on filter sampling followed by laboratory analysis, which provided datasets at a coarse time resolution like a day. The coarse time resolution of the aerosol datasets cannot match the actual faster variation of aerosol properties in the real atmosphere, which strongly favors highly time-resolved on-line measurement techniques. In recent years, our group deployed an Aerodyne high-resolution aerosol mass spectrometer (AMS) in different ambient atmospheres in China, including Beijing (urban), Shanghai (urban), Shenzhen (urban), Jiaxing (suburban), and Kaiping (rural). In this presentation, we will overview these on-line AMS measurement results to characterize the properties of submicron particles in China atmosphere, such as chemical composition, size distribution, diurnal variation, elemental composition, primary and secondary organic aerosol constitution, etc. The newly-developed AMS-PMF modeling techniques were utilized to quantitatively differentiate the contributions from fossil fuel combustion, cooking emissions, biomass burning, as well as secondary organic aerosol to ambient organic aerosol loadings in China. These AMS results have provided new outlook of the formation mechanisms of high aerosol pollution in China.

Huang, X.; He, L.; Gong, Z.; Hu, M.; Zhang, Y.

2011-12-01

326

Acid aerosol transport episodes in Toronto, Ontario  

SciTech Connect

In this paper, the authors examine the pollution data collected during a 1986 field study in order to assess the nature and sources of acidic aerosols in the Toronto metropolitan area during this period. Through the examination of the continuous and filter aerosol data, isobaric back-trajectories of air masses, weather maps, and available trace element data, assessment are made of the character and possible sources of acid aerosols in this Southern Ontario city.

Thurston, G.D. (New York Univ., Tuxedo, NY (USA). Inst. of Environmental Medicine); Waldman, J. (Robert Wood Johnson Medical School, Piscataway, NJ (US))

1987-01-01

327

Microfluidic paper-based analytical device for aerosol oxidative activity.  

PubMed

Human exposure to particulate matter (PM) air pollution has been linked with respiratory, cardiovascular, and neurodegenerative diseases, in addition to various cancers. Consistent among all of these associations is the hypothesis that PM induces inflammation and oxidative stress in the affected tissue. Consequently, a variety of assays have been developed to quantify the oxidative activity of PM as a means to characterize its ability to induced oxidative stress. The vast majority of these assays rely on high-volume, fixed-location sampling methods due to limitations in assay sensitivity and detection limit. As a result, our understanding of how personal exposure contributes to the intake of oxidative air pollution is limited. To further this understanding, we present a microfluidic paper-based analytical device (?PAD) for measuring PM oxidative activity on filters collected by personal sampling. The ?PAD is inexpensive to fabricate and provides fast and sensitive analysis of aerosol oxidative activity. The oxidative activity measurement is based on the dithiothreitol assay (DTT assay), uses colorimetric detection, and can be completed in the field within 30 min following sample collection. The ?PAD assay was validated against the traditional DTT assay using 13 extracted aerosol samples including urban aerosols, biomass burning PM, cigarette smoke, and incense smoke. The results showed no significant differences in DTT consumption rate measured by the two methods. To demonstrate the utility of the approach, personal samples were collected to estimate human exposures to PM from indoor air, outdoor air on a clean day, and outdoor air on a wildfire-impacted day in Fort Collins, CO. Filter samples collected on the wildfire day gave the highest oxidative activity on a mass normalized basis, whereas typical ambient background air showed the lowest oxidative activity. PMID:23227907

Sameenoi, Yupaporn; Panymeesamer, Pantila; Supalakorn, Natcha; Koehler, Kirsten; Chailapakul, Orawon; Henry, Charles S; Volckens, John

2012-12-21

328

Dry Deposition of Fine Aerosol Nitrogen to an Agricultural Field Measured by Eddy-Correlation Mass Spectrometry  

NASA Astrophysics Data System (ADS)

In urban areas high emissions of reactive nitrogen species cause an increase in atmospheric aerosol nitrogen formation and deposition. This nitrogen is eventually removed from the atmosphere by wet or dry deposition, with dry deposition often accounting for more than half of the total deposition of particulate nitrate (Lovett, 1994). Total N deposition is not adequately characterized, in part because dry deposition is difficult to measure or model. For example measured fine particle deposition to a forest canopy differs from predicted values by an order of magnitude (Gallagher et al., 1997). The eddy-correlation technique is a micrometeorological method used to directly measure fluxes from measurements made above the surface (Wesely and Hicks, 2000). Eddy-correlation mass spectrometry (ECMS) has been developed to directly measure aerosol particle deposition velocities from fast response aerosol concentration and wind velocity measurements. Using an Aerodyne Aerosol Mass Spectrometer (AMS) (Jayne et al., 2000), the size and composition of ambient aerosols is measured at a high frequency. The AMS signal is proportional to non-refractory PM1.0 mass. Aerosol deposition fluxes for a given averaging period are then calculated directly as the covariance of the vertical wind velocity with the AMS signal (F = -/line{w'S'}). A field study was conducted to measure aerosol nitrogen dry deposition to an agricultural field immediately downwind of the Phoenix metropolitan area using eddy-correlation mass spectrometry. The study was supplemented with aerosol composition measurements including bulk deposition collectors and filter bank samplers. Bulk deposition samples and 24-hour filter samples were analyzed for ammonia and nitrogen. Here we compare the results of the flux estimates from bulk collection with inferential measurements (filter samples and modeled deposition velocities) and direct micrometeorological measurements (ECMS) in order to improve N deposition estimates.

Gonzales, D. A.; Allen, J. O.; Smith, K. A.; Hope, D.

2004-12-01

329

Emission Rates of PM Constituents from Highly Time-Resolved Ambient Concentration Measurements: A New Paradigm in Air Pollution Management  

NASA Astrophysics Data System (ADS)

Highly-time resolved metals measurements were made in the Bay Regional Atmospheric Chemistry Experiment and at four other urban locations using the University of Maryland Semicontinuous Elements in Aerosol Sampler. Aerosol slurry samples were collected at 30-minute intervals, i.e., at periods short relative to changes in wind direction, and analyzed off-line by mutli-element graphite furnace Atomic Absorption Spectroscopy for up to 12 elements useful as markers of primary particle emissions of high-temperature combustion sources. At this resolution, the plumes of individual sources, including coal- and oil-fired power plants, and a battery recycling plant, were readily observed as excursions in time series profiles of the concentrations of the various marker elements. Over the scale of 40 km, wind and source angles are nearly identical when the former are relatively constant during the time required for plume transport. Herein, ambient data collected at the Sydney site were combined with available stack emission measurements of SO2, along with meteorological data in a pseudo deterministic least squares model in which ambient concentrations are reconclied with the products of emission rates and dispersion factors for known sources. The model encompasses horrizontal and vertical gaussian dispersion terms as constraints and is used to estimate estimate emission rates of the various species from the known sources. Ambient ground-level measurements made in the vicinity of the Sydney site will be presented along with some the model estimates of emission rates from various sources.

Ondov, J.; Pancras, P.; Park, S. S.; Poor, N.

2003-12-01

330

Mesospheric Aerosol Sampling Spectrometer  

NASA Astrophysics Data System (ADS)

An instrument has been developed to detect charged, sub-visible aerosol particles in the polar mesosphere. Two of these instruments were launched in August, 2007 from Andoya, Norway as part of the Mesospheric Aerosol Sampling Spectrometer (MASS) campaign and both detected charged aerosols. These in-situ measurements coincided with measurements by the Aeronomy of Ice in the Mesosphere (AIM) satellite and the German/Norwegian Existence and Charge state Of Meteoric dust grains in the middle Atmosphere (ECOMA) rocket campaign. This instrument has a 25 square centimeter entrance slit that admits a continuous flow of air. Venting ports are placed lower on the detector in order to reduce pressure buildup. The air sample flows between three pairs of graphite electrodes biased symmetrically with increasing bias potentials. Electrons, light ions, cluster ions and heavy charged aerosol particles of both polarities are collected mass-selectively on the electrodes that are connected to sensitive electrometers. Direct Simulation Monte Carlo (DSMC) codes have been used to optimize the supersonic airflow within and around the instrument. The calibration of the MASS instrument as well as preliminary results will be shown. Acknowledgement: This project is supported by NASA.

Knappmiller, S.; Robertson, S.; Horanyi, M.; Kohnert, R.; Sternovsky, Z.; Baumgarten, G.; Latteck, R.; Rapp, M.

2007-12-01

331

GENERATION, TRANSPORT AND DEPOSITION OF TUNGSTEN-OXIDE AEROSOLS AT 1000 C IN FLOWING AIR-STEAM MIXTURES.  

SciTech Connect

Experiments were conducted to measure the rates of oxidation and vaporization of pure tungsten rods in flowing air, steam and air-steam mixtures in laminar flow. Also measured were the downstream transport of tungsten-oxide condensation aerosols and their region of deposition, including plateout in the superheated flow tube, rainout in the condenser and ambient discharge which was collected on an array of sub-micron aerosol filters. The nominal conditions of the tests, with the exception of the first two tests, were tungsten temperatures of 1000 C, gas mixture temperatures of 200 C and wall temperatures of 150 C to 200 C. It was observed that the tungsten oxidation rates were greatest in all air and least in all steam, generally decreasing non-linearly with increasing steam mole fraction. The tungsten oxidation rates in all air were more than five times greater than the tungsten oxidation rates in all steam. The tungsten vaporization rate was zero in all air and increased with increasing steam mole fraction. The vaporization rate became maximum at a steam mole fraction of 0.85 and decreased thereafter as the steam mole fraction was increased to unity. The tungsten-oxide was transported downstream as condensation aerosols, initially flowing upwards from the tungsten rod through an 18-inch long, one-inch diameter quartz tube, around a 3.5-inch radius, 90{sup o} bend and laterally through a 24-inch horizontal run. The entire length of the quartz glass flow path was heated by electrical resistance clamshell heaters whose temperatures were individually controlled and measured. The tungsten-oxide plateout in the quartz tube was collected, nearly all of which was deposited at the end of the heated zone near the entrance to the condenser which was cold. The tungsten-oxide which rained out in the condenser as the steam condensed was collected with the condensate and weighed after being dried. The aerosol smoke which escaped the condenser was collected on the sub-micron filter assemblies. There was no aerosol generation for the case of all air, so the plateout, condensate and smoke were all zero. For the case of all steam, there was very little plateout in the superheated regions (several percent) and the rest of the aerosol was collected in the condensate from the condenser. There was no smoke discharge into the filters. For the experiments with intermediate air-steam fractions, there was some aerosol plateout, considerable aerosol in the condensate and aerosol smoke discharged from the condenser with the escaping air.

GREENE,G.A.; FINFROCK,C.C.

2001-10-01

332

Organosulfate Formation in Biogenic Secondary Organic Aerosol  

EPA Science Inventory

Organosulfates of isoprene, α-pinene, and β-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 seri...

333

Harmonizing Molecular Marker Analyses of Organic Aerosols  

Microsoft Academic Search

Analysis of molecular markers in aerosol samples using GC-MS has become widely used in air pollution studies. There is considerable variability in the analytical details of molecular marker analyses across different research and regulatory groups. These discrepancies result in the use of different methods for the interpretation of source and ambient measurements used in source apportionment and atmospheric particulate studies.

Yuan Xun Zhang; James Jay Schauer; Elizabeth Anne Stone; Yuanhang Zhang; Min Shao; Yongjie Wei; Xianlei Zhu

2009-01-01

334

METHODS OF CALCULATINAG LUNG DELIVERY AND DEPOSITION OF AEROSOL PARTICLES  

EPA Science Inventory

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

335

Photoformation Rate of OH radical in Water-Extract of Atmospheric Aerosol and Water-Soluble Gases Collected in Higashi-Hiroshima, Japan  

NASA Astrophysics Data System (ADS)

The hydroxyl radical (?OH) photoformation rate (ROH), chemical composition and primary generation sources of ?OH in the atmospheric water-extract of aerosol (WEA) and water-soluble gaseous (WSG) fractions were studied at Higashi-Hiroshima from June 2008 to June 2010. Among the major anions being present in the WSG samples, the SO42- concentration was highest (9.8±2.9 nmol m-3), followed by NO3- and Cl-, while for WEA fractions the mean concentration of SO42- was 81±33 nmol m-3. The concentration of H2O2 was 0.2±0.3 and 0.9±2.3 nmol m-3 in the WSG and WEA, respectively. Using a solar simulator, the extracted sample was irradiated and the ROH was determined and normalized based on the air-volume, which revealed values of 1.4 and 0.5 nmol h-1 m-3 for the WEA and WSG, respectively. Linear relationship between irradiation time and production of ?OH in both fractions suggested high capacity or similar efficiency of ?OH generation. The contribution of NO3-, NO2- and H2O2 to the formation of ?OH via photolysis were 4.5, 0.7 and 1.2%, respectively, for the WSG fraction, while in the WEA fraction, NO3-, NO2- and H2O2 contributed 8.9, 1.2 and 2.5%, respectively. The photo-Fenton reaction contributed 42% of the total ?OH formation in the WSG fraction, while unknown sources that might be humic-like substances (HULIS) accounted for the remaining 52%.

Nomi, S. N.; Sakugawa, H. H.; Kondo, H.

2011-12-01

336

Phase transformation and growth of hygroscopic aerosols  

SciTech Connect

Ambient aerosols play an important role in many atmospheric processes affecting air quality, visibility degradation, and climatic changes as well. Both natural and anthropogenic sources contribute to the formation of ambient aerosols, which are composed mostly of sulfates, nitrates, and chlorides in either pure or mixed forms. These inorganic salt aerosols are hygroscopic by nature and exhibit the properties of deliquescence and efflorescence in humid air. For pure inorganic salt particles with diameter larger than 0.1 micron, the phase transformation from a solid particle to a saline droplet occurs only when the relative humidity in the surrounding atmosphere reaches a certain critical level corresponding to the water activity of the saturated solution. The droplet size or mass in equilibrium with relative humidity can be calculated in a straightforward manner from thermodynamic considerations. For aqueous droplets 0.1 micron or smaller, the surface curvature effect on vapor pressure becomes important and the Kelvin equation must be used.

Tang, I.N.

1999-11-01

337

Contributions of fossil fuel, biomass-burning, and biogenic emissions to carbonaceous aerosols in Zurich as traced by 14C  

NASA Astrophysics Data System (ADS)

Many open questions exist about the importance of different sources of carbonaceous aerosol, which is a substantial contributor to the global aerosol budget and, therefore, to climate change and human mortality. In this work, 14C was determined in elemental carbon (EC) and different organic carbon (OC) fractions from ambient urban aerosols with aerodynamic diameter <10 ?m collected in Zurich (Switzerland). This enabled a more detailed source attribution of the carbonaceous aerosol mass than is possible with other currently available methods. The three major sources, fossil fuel, wood combustion (both anthropogenic emissions), and biogenic emissions, were quantified, making specific regulatory air quality management measures possible. EC originates nearly exclusively from fossil fuel usage during summer, whereas biomass-burning emissions become substantial during winter with ˜25%, even though this source contributes only marginally to the local energy consumption. For OC, biogenic sources are dominant in summer with ˜60%, where secondary organic aerosol prevails. Wood combustion accounts for up to ˜41% of OC in winter. Fossil fuels represent ˜30% of OC throughout the year.

Szidat, SöNke; Jenk, Theo M.; Synal, Hans-Arno; Kalberer, Markus; Wacker, Lukas; Hajdas, Irka; Kasper-Giebl, Anne; Baltensperger, Urs

2006-04-01

338

Apparatus for sampling and characterizing aerosols  

DOEpatents

Apparatus for sampling and characterizing aerosols having a wide particle size range at relatively low velocities may comprise a chamber having an inlet and an outlet, the chamber including: a plurality of vertically stacked, successive particle collection stages; each collection stage includes a separator plate and a channel guide mounted transverse to the separator plate, defining a labyrinthine flow path across the collection stage. An opening in each separator plate provides a path for the aerosols from one collection stage to the next. Mounted within each collection stage are one or more particle collection frames.

Dunn, Patrick F. (Downers Grove, IL); Herceg, Joseph E. (Naperville, IL); Klocksieben, Robert H. (Park Forest, IL)

1986-01-01

339

Importance of aerosol phase upon aerosol oxidation  

NASA Astrophysics Data System (ADS)

The chemical processing of organic aerosol changes the composition of the aerosol. If the composition becomes more volatile, then the aerosol can become a source of gaseous oxygenated volatile organic compounds (OVOC). At present, the global budget of OVOC is poorly constrained. Increased oxidation of the aerosol, generally leads to greater aerosol hygroscopicity and a hence a greater propensity for the aerosol to form cloud condensation nuclei. Therefore the radiative effects of the aerosol will change upon oxidation. We will present a single particle study on maleic acid aerosol using the electrodynamic balance methodology. The ozonolysis of the maleic acid particle is found to be phase dependent. The ozonolysis of deliquesced particles show distinct differences to the ozonolysis of dry particles. Differences include the change in hygroscopicity and hence aerosol composition. The volatility of the ozonolysis products is also dependent upon the phase of aerosol during the ozonolysis event.1 This study highlights the necessity to investigate aerosol reactivity under different relative humidities. The oxidation of organic aerosol in general should be very dependent upon aerosol phase. We will also present complementary mass spectrometric results on maleic acid aerosol ensembles where clear chemical differences are observed in the aerosol composition when ozonolysis is performed under different relative humidities. The chemical mechanisms responsible for the ozonolysis of aerosol composed of small highly oxidised species differs greatly from the chemistry of aerosols composed of longer and less oxidised species (e.g. oleic acid). A discussion on the importance of these chemical differences for global aerosol populations will be provided. (1) Pope et al. (2010) Ozonolysis of maleic acid aerosols: Effect upon aerosol hygroscopicity, phase and mass. Environ. Sci. Technol. 44 (17), 6656.

Pope, F. D.; Achakulwisut, P.; Gallimore, P.; Kalberer, M.

2010-12-01

340

Characterization of urban aerosol in Cork City (Ireland) using aerosol mass spectrometry  

NASA Astrophysics Data System (ADS)

Ambient wintertime background urban aerosol in Cork City, Ireland, was characterized using aerosol mass spectrometry. During the three-week measurement study in 2009, 93% of the 1 200 000 single particles characterized by an Aerosol Time-Of-Flight Mass Spectrometer (TSI ATOFMS) were classified into five organic-rich particle types, internally-mixed to different proportions with Elemental Carbon (EC), sulphate and nitrate while the remaining 7% was predominantly inorganic in nature. Non-refractory PM1 aerosol was also characterized using a High Resolution Time-Of-Flight Aerodyne Aerosol Mass Spectrometer (HR-ToF-AMS) and was also found to comprise organic matter as the most abundant species (62%), followed by nitrate (15%), sulphate (9%) and ammonium (9%), and then chloride (5%). Positive matrix factorization (PMF) was applied to the HR-ToF-AMS organic matrix and a five-factor solution was found to describe the variance in the data well. Specifically, "Hydrocarbon-like" Organic Aerosol (HOA) comprised 19% of the mass, "Oxygenated low volatility" Organic Aerosols (LV-OOA) comprised 19%, "Biomass wood Burning" Organic Aerosol (BBOA) comprised 23%, non-wood solid-fuel combustion "Peat and Coal" Organic Aerosol (PCOA) comprised 21%, and finally, a species type characterized by primary m/z peaks at 41 and 55, similar to previously-reported "Cooking" Organic Aerosol (COA) but possessing different diurnal variations to what would be expected for cooking activities, contributed 18%. Despite wood, cool and peat being minor fuel types used for domestic space heating in urban areas, their relatively low combustion efficiencies result in a significant contribution to PM1 aerosol mass (44% and 28% of the total organic aerosols mass and non refractory PM1, respectively).

Dall'Osto, M.; Ovadnevaite, J.; Ceburnis, D.; Martin, D.; Healy, R. M.; O'Connor, I. P.; Sodeau, J. R.; Wenger, J. C.; O'Dowd, C.

2012-11-01

341

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

SciTech Connect

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).

Mazurek, M.A. [Brookhaven National Lab., Upton, NY (United States); Cofer, W.R. III; Levine, J.S. [National Aeronautics and Space Administration, Hampton, VA (United States). Langley Research Center

1990-10-01

342

Size distribution and sources of aerosol in Launceston, Australia, during winter 1997.  

PubMed

As part of a pilot study into the chemical and physical properties of Australian fine particles, a suite of aerosol samples was collected at Ti Tree Bend in Launceston, Tasmania, during June and July 1997. This period represents midwinter in the Southern Hemisphere, a period when aerosol sources in Launceston are dominated by smoke from domestic wood burning. This paper describes the results from this measurement campaign, with the aim of assessing the effect of wood smoke on the chemical and physical characteristics of ambient aerosol. A micro orifice uniform deposit impactor (MOUDI) was used to measure the size distributions of the aerosol from 0.05 to 20 microns aerodynamic diameter. Continuous measurements of fine particle mass were made using a PM2.5 tapered element oscillating microbalance (TEOM) and light scattering coefficients at 530 nm were measured with nephelometers. Mass size distributions tended to be bimodal, with the diameter of the dominant mode tending to smaller sizes with increases in total mass. Non-sea salt potassium and polycyclic aromatic hydrocarbons (PAHs) were used as chemical tracers for wood smoke. Wood smoke was found to increase absolute particle mass (enough to regularly exceed air quality standards), and to concentrate mass in a single mode below 1 micron aerodynamic diameter. The acid-base equilibrium of the aerosol was altered by the wood smoke source, with free acidity hydrogen ion, non-sea salt sulfate, and ammonium concentrations being higher and the concentration of all species, including nitrate (to differing extents), focused in the fine particle size ranges. The wood smoke source also heavily influenced the aerosol scattering efficiency, adding to a strong diurnal cycle in both mass concentration and light scattering. PMID:10734713

Keywood, M D; Ayers, G P; Gras, J L; Gillett, R W; Cohen, D D

2000-03-01

343

INDOOR AEROSOLS AND AEROSOL EXPOSURE  

EPA Science Inventory

The average American spends an overwhelming portion of his/her time indoors. t is probable that the majority of ones exposure to pollutants will also occur indoors. ampling aerosols for risk assessment in the indoor environment present peculiar problems because of the relatively ...

344

How well do state-of-the-art techniques measuring the vertical profile of tropospheric aerosol extinction compare?  

Microsoft Academic Search

The recent Department of Energy Atmospheric Radiation Measurement (ARM) Aerosol Intensive Operations Period (AIOP, May 2003) yielded one of the best measurement sets obtained to date to assess our ability to measure the vertical profile of ambient aerosol extinction ?ep(?) in the lower troposphere. During one month, a heavily instrumented aircraft with well-characterized aerosol sampling ability carrying well-proven and new

B. Schmid; R. Ferrare; C. Flynn; R. Elleman; D. Covert; A. Strawa; E. Welton; D. Turner; H. Jonsson; J. Redemann; J. Eilers; K. Ricci; A. G. Hallar; M. Clayton; J. Michalsky; A. Smirnov; B. Holben; J. Barnard

2006-01-01

345

The fluorescence properties of aerosol larger than 0.8 mum in urban and tropical rainforest locations  

Microsoft Academic Search

UV-LIF measurements were performed on ambient aerosol in Manchester, UK (urban city centre, winter) and Borneo, Malaysia (remote, tropical) using a Wide Issue Bioaerosol Spectrometer, version 3 (WIBS3). These sites are taken to represent environments with minor and significant primary biological aerosol (PBA) influences respectively, and the urban dataset describes the fluorescent background aerosol against which PBA must be identified

A. M. Gabey; W. R. Stanley; M. W. Gallagher; P. H. Kaye

2011-01-01

346

COMPOSITION OF AEROSOLS OVER LOS ANGELES FREEWAYS  

EPA Science Inventory

In October of 1976, aerosol particulate samples were collected while driving on Los Angeles freeways and were analyzed for sulfate, nitrate, and elemental composition. The measurements indicate that neither nitrate nor sulfate concentrations increased significantly over the roadw...

347

Marine Aerosol Production, Chemical Evolution, and Feedbacks  

NASA Astrophysics Data System (ADS)

Production of primary marine aerosols by bursting bubbles from breaking waves at the ocean surface is a major process in the earth's climate system with important implications for the physiochemical evolution of the troposphere and feedbacks on upper ocean biogeochemistry. Nascent marine aerosol mass and volume are dominated by super-?m-diameter particles comprised primarily of inorganic sea salt and water. Corresponding number concentrations are dominated by hygroscopic sub-?m-diameter particles that are highly enriched in organic carbon. Freshly produced marine aerosols dehydrate into equilibrium with ambient water vapor and undergo rapid chemical transformation involving the photolysis of primary organic compounds, scavenging of gases, aqueous and surface reactions, and volatilization of products including halogen-radical precursors. Associated multi-phase chemical pathways modify oxidation regimes relative to conventional HOx-NOx photochemistry via direct destruction of ozone, accelerating oxidation of NOx, dimethysulfide, alkanes, and mercury in the gas phase; and oxidation of S(IV) in acidic aerosol solutions. The large surface area of marine aerosol also competes effectively with nuclear clusters for condensable, gas-phase reaction products thereby minimizing production of new particles via nucleation and growth pathways and their associated radiative effects. In addition, primary marine aerosols influence radiative transfer directly via scattering and indirectly via modulating cloud microphysics. This paper will review current understanding of marine aerosol production and processing in the context of earth system science and summarize major areas of uncertainty.

Keene, W. C.

2011-12-01

348

Phase transformation and growth of hygroscopic aerosols  

SciTech Connect

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

Tang, I.N.

1995-09-01

349

Large-scale aerosol source apportionment in Amazonia  

NASA Astrophysics Data System (ADS)

Aerosol particles were collected aboard two Brazilian Bandeirante EMB 110 planes, and the University of Washington Convair C-131A aircraft during the Smoke, Clouds, and Radiation-Brazil (SCAR-B) field project in the Amazon Basin in August and September 1995. Aerosols were collected on Nuclepore and Teflon filters. Aerosol size distribution was measured with a MOUDI cascade impactor. Sampling was performed mostly over areas heavily influenced by biomass burning smoke. Particle-induced X ray emission (PIXE) was used to measure concentrations of up to 20 elements (Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, Zr, and Pb). Black carbon (BC) and gravimetric mass analysis were also performed. Instrumental neutron activation analysis (INAA) determined the concentrations of about 15 elements on the Teflon filters. Electron probe X ray microanalysis (EPMA) was used to analyze individual aerosol particles. The average aerosol mass concentration was 105 ?g m-3, with a maximum of 297 ?g m-3. Black carbon (BC) averaged 5.49 ?g m-3, or 1-7% of the aerosol mass load. Five aerosol components were revealed by absolute principal factor analysis: (1) a biomass burning component (responsible for 54% of the aerosol mass and associated with BC, K, Cl, Zn, I, S, Br, Rb, aerosol mass concentration, and other elements); (2) a soil dust aerosol component (15.6% of the aerosol mass); (3) a natural biogenic component (18.7% of the aerosol mass and associated with P, K, S, Ca, Sr, Mg, Mn, Cu and Zn); (4) a second soil dust (5.7% of the aerosol mass and enriched in Si, Ti, and Fe); and (5) a NaCl aerosol component (5.9% of the aerosol mass with Na, Cl, Br, and iodine). Electron microscopy analysis of individual aerosol particles confirmed these five aerosol types. Organic material dominated the aerosol mass and the number concentration of airborne particles. Aerosol size distributions show that the fine mode accounts for 78% of the aerosol mass, centered at 0.33 ?m aerodynamic diameter. The coarse mode accounts for 22% of the mass, centered at about 3.2 ?m. Black carbon size distributions show a consistent picture, with a mass median diameter centered at about 0.175-0.33 ?m aerodynamic diameter. This study suggests that for modeling the optical properties of aerosol in the Amazon Basin, it is essential to use a model that includes the optical and physical properties of at least two aerosol components other than the biomass burning aerosol, namely, natural biogenic aerosol and soil dust.

Artaxo, Paulo; Fernandas, Eduardo T.; Martins, José V.; Yamasoe, MáRcia A.; Hobbs, Peter V.; Maenhaut, Willy; Longo, Karla M.; Castanho, Andrea

1998-12-01

350

Aerosol Impacts on Microphysical and Radiative Properties of Stratocumulus Clouds in the Southeast Pacific  

NASA Astrophysics Data System (ADS)

The southeast Pacific Ocean is covered by the world's largest stratocumulus cloud layer, which has a strong impact on ocean temperatures and climate in the region. The effect of anthropogenic sources of aerosol particles was investigated during the VOCALS field experiment. Aerosol measurements below and above cloud were made with a ultra-high sensitivity aerosol spectrometer and analytical electron microscopy. In addition to more standard in-cloud measurements, cloud droplets were collected and evaporated using a counterflow virtual impactor (CVI), and the non-volatile residual particles were analyzed. Many flights focused on the gradient in cloud properties along an E-W track from near the Chilean coast to remote areas offshore. Mean statistics from seven flights were compiled. Consistent with a continental source of cloud condensation nuclei, below-cloud accumulation-mode aerosol and droplet number concentration generally decreased from near shore to offshore. The effect extends ~800 to 1000 km from shore. The additional particles are mainly sulfates from anthropogenic sources. Liquid water content and drizzle concentration tended to increase with distance from shore, but exhibited much greater variability. Analysis of the droplet residual measurements showed that not only were there more residual nuclei near shore, but that they tended to be larger than those offshore. Single particle analysis over a broad particle size range was used to reveal types and sources of CCN, which were primarily sulfates near shore. Differences in the size distribution of droplet residual particles and ambient aerosol particles were observed due to the preferential activation of large aerosol particles. By progressively excluding small droplets from the CVI sample, we were able to show that the larger drops, which initiate drizzle, contain the largest aerosol particles. However, the scavenging efficiency is not sharp as expected from a simple parcel activation model. A wide range of particle sizes, down to at least 55 nm in size, act as droplet nuclei in these stratocumulus clouds. A detailed LES microphysical model was used to show this can occur without invoking differences in chemical composition. Aerosol number concentration in the >0.05 and >0.1 ?m size ranges was correlated with droplet number concentration, and anti-correlated with droplet effective radius, and the effect is statistically significant. The impact of aerosol pollutants was to increase droplet number and decrease droplet size within a region extending about 1000 km offshore. Cloud droplets were more numerous and smaller near shore, and there was less drizzle. However, MODIS satellite measurements were used to show that despite the smaller droplets near shore, cloud albedo is not higher near shore than offshore. This is due to the generally thinner clouds and lower liquid water path near shore.

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

2011-12-01

351

Radiocarbon source apportionment of carbonaceous aerosol components of South Asian Atmospheric Brown Clouds  

NASA Astrophysics Data System (ADS)

Light-absorbing carbonaceous matter constitutes one of the largest uncertainties in climate modeling. The high concentrations of black carbon - soot - in South Asian Atmospheric Brown Clouds lead to strong atmospheric heating and large surface cooling that is as important to regional climate forcing as greenhouse gases, yet the sources of these aerosols are not well understood. Emission inventory models suggest that biofuel/biomass burning accounts for 60-90% of the sources of these aerosol components whereas measurements of the elemental composition of ambient aerosols compared with source signatures point to combustion of fossil fuel as the primary culprit. However, both approaches acknowledge large uncertainties in source apportionment of the elusively-defined black carbon. This study approached the sourcing challenge by applying microscale radiocarbon measurements to aerosol particles collected during the winter in North India, Central India and over the Indian Ocean receptor (The Maldives). The radiocarbon approach is ideally suited to this task as fossil sources are void of 14C whereas biomass combustion products hold a contemporary 14C signal. In a first pilot study in 2006, high-volume air samples of total carbonaceous aerosols revealed 14C signals that were similar for a Central Indian source region site located in Sinighad, near Pune, and an Indian Ocean receptor (the Maldives), consistent with the absence of any significant formation of secondary organic aerosols, with a 60-70% contribution from biomass combustion and biogenic sources. Isolates of elemental or soot carbon fractions varied between 40-70%, depending on isolation method. A subsequent 15-month continuous probing of these two sites in 2008-2009 confirmed an average contribution of two-thirds from contemporary sources to the TOC. The 14C-data revealed a stronger contemporary signal arriving to the Maldives in May-June, presumably due to biogenic secondary organic aerosols. A period of stronger fossil contributions was also found near Pune in mid to late summer. The first 14C data for northern India revealed for two sites (Hisar and Manora Peak) that the total carbonaceous aerosols were only 30% from fossil-fuel origin. These novel radiocarbon constraints on the sources of light-absorbing carbonaceous matter aid prioritizing what combustion processes to target for emission mitigations of these health-afflicting and climate-forcing aerosols in the South Asian region.

Gustafsson, Örjan; Krusâ, Martin; Sheesley, Rebecca; Praveen, P. S.; Rao, P. S. P.; Safai, P. D.; Budhavant, K.; Rengarajan, R.; Sudheer, A. K.; Sarin, M. M.

2010-05-01

352

Aerosol Mobility Size Spectrometer.  

National Technical Information Service (NTIS)

A device for measuring aerosol size distribution within a sample containing aerosol particles. The device generally includes a spectrometer housing defining an interior chamber and a camera for recording aerosol size streams exiting the chamber. The housi...

J. Wang P. Kulkarni

2004-01-01

353

Measurements of Natural Radioactivity in Submicron Aerosols in the Pittsburgh Area.  

NASA Astrophysics Data System (ADS)

Natural radionuclides can be useful in evaluating the transport of ozone and aerosols in the troposphere. We have used natural radioactivity to estimate apparent residence times for submicron aerosols in the troposphere by looking at the disequilibrium of lead-210 with its daughters bismuth-210 (5-day half-life) and polonium-210 (138-day half-life). We have also measured the activity of beryllium-7 on fine aerosols to examine potential upper-air transport into the tropospheric boundary layer. Two sites in the Pittsburgh area during the summer of 2001 were sampled for beryllium-7, lead-210, bismuth-210, and polonium-210 on fine aerosols by using a Sierra Impactor (Stage 4) that allowed a nominal 1-micrometer cutoff diameter. One site was located approximately 5 km east of downtown Pittsburgh, on a rooftop next to Schenley Park (40.4395o N latitude and 79.9405o W longitude, elevation 310 m). A second site was located at the U.S. Department of Energy National Energy Technology Laboratory (NETL) Ambient Air Monitoring Station, approximately 15 km south of downtown Pittsburgh (40.30655 deg N latitude and 79.9794 deg W longitude, elevation 325 m). At both sites, 24-hour samples were collected from July 22 to July 30, 2001. Nine samples were taken at the NETL site, and six were taken at the Schenley Park site. The method for determining the lead-210 and its daughters will be described briefly. Apparent residence times ranged from 10-46 days, with an average of 23 days. Data indicate that little wind-blown soil or dust affected the area during the study. The importance of fine aerosol transport will be emphasized. The authors wish to thank Donald Martello of the NETL and Natalie J. Anderson of Carnegie Mellon University for sample collection. This work was supported by the United States Department of Energy, Atmospheric Chemistry Program.

Marley, N.; Gaffney, J. S.

2002-12-01

354

Variation of marine aerosol acidity with particle size  

NASA Astrophysics Data System (ADS)

pHs were measured in minimally diluted extracts of size-segregated aerosols sampled under moderately polluted conditions at Bermuda during spring 1997. Extrapolation to aerosol liquid water contents yielded ambient pHs for most super-?m diameter size fractions in the upper 3s to upper 4s. Aerosols within this size range of each sample approached similar pH. These results are consistent with recent estimates of sea-salt aerosol pHs based on thermodynamic considerations and model calculations. Most pHs for finer aerosol size fractions were in the 1s and 2s. The H+ + SO42- <-> HSO4- equilibrium strongly buffered aerosol pH in all size fractions.

Keene, William C.; Pszenny, Alexander A. P.; Maben, John R.; Sander, Rolf

2002-04-01

355

Observations of OM/OC and specific attenuation coefficients (SAC) in ambient fine PM at a rural site in central Ontario, Canada  

NASA Astrophysics Data System (ADS)

Ambient particulate matter (PM) samples were collected on quartz filters at a rural site in central Ontario during an intensive study in 2007. The concentrations of organic carbon (OC), pyrolysis organic carbon (POC), and elemental carbon (EC) were determined by thermal analysis. The concentrations are compared to the organic aerosol mass concentration (OM) measured with an Aerodyne C-ToF Aerosol Mass Spectrometer (AMS) and to the particle absorption coefficient (basp) obtained from a Radiance Research Particle Soot Absorption Photometer (PSAP). The total organic mass to organic carbon ratios (OM/OC) and specific attenuation coefficients (SAC=basp/EC) are derived. Proportionality of the POC mass with the oxygen mass in the aerosols estimated from the AMS offers a potential means to estimate OM/OC from thermal measurements only. The mean SAC for the study is 3.8±0.3 m2 g-1. It is found that the SAC is independent of or decrease with increasing particle mass loading, depending on whether or not the data are separated between aerosols dominated by more recent anthropogenic input and aerosols dominated by longer residence time or biogenic components. There is no evidence to support an enhancement of light absorption by the condensation of secondary material to particles, suggesting that present model simulations built on such an assumption may overestimate atmospheric warming by BC.

Chan, T. W.; Huang, L.; Leaitch, W. R.; Sharma, S.; Brook, J. R.; Slowik, J. G.; Abbatt, J. P. D.; Brickell, P. C.; Liggio, J.; Li, S.-M.; Moosmüller, H.

2010-03-01

356

Tropospheric Aerosols  

Microsoft Academic Search

\\u000a Between 1970 and 1990 the major advances in atmospheric chemistry were made in gas-phase photochemistry, except perhaps for\\u000a a brief intermezzo of “nuclear winter” studies. This focus is now shifting, as it is recognised that natural and anthropogenic\\u000a aerosols play a substantial role in the radiative properties of the atmosphere and Earth’s climate. In addition, studies on\\u000a the causes of

Jost Heintzenberg; Frank Raes; Stephen E. Schwartz; Ingmar Ackermann; Paulo Artaxo; Timothy S. Bates; Carmen Benkovitz; Keith Bigg; Tami Bond; Jean-Louis Brenguier; Fred L. Eisele; Johann Feichter; Andrea I. Flossman; Sandra Fuzzi; Hans-F. Graf; Jeremy M. Hales; Hartmut Herrmann; Thorsten Hoffmann; Barry Huebert; Rudolf B. Husar; Ruprecht Jaenicke; Bernd Kärcher; Yoram Kaufman; Geoffrey S. Kent; Markku Kulmala; Caroline Leck; Catherine Liousse; Ulrike Lohmann; Beatrice Marticorena; Peter McMurry; Kevin Noone; Colin O’Dowd; Joyce E. Penner; Alex Pszenny; Jean-Philipe Putaud; Patricia K. Quinn; Ulrich Schurath; John H. Seinfeld; Herman Sievering; Jeffrey Snider; Irina Sokolik; Frank Stratmann; Rita Dingenen; Douglas Westphal; Anthony S. Wexler; Alfred Wiedensohler; David M. Winker; Julian Wilson

1993-01-01

357

Capstone Depleted Uranium Aerosols: Generation and Characterization  

SciTech Connect

In a study designed to provide an improved scientific basis for assessing possible health effects from inhaling depleted uranium (DU) aerosols, a series of DU penetrators was fired at an Abrams tank and a Bradley fighting vehicle. A robust sampling system was designed to collect aerosols in this difficult environment and continuously monitor the sampler flow rates. Aerosols collected were analyzed for uranium concentration and particle size distribution as a function of time. They were also analyzed for uranium oxide phases, particle morphology, and dissolution in vitro. The resulting data provide input useful in human health risk assessments.

Parkhurst, MaryAnn; Szrom, Fran; Guilmette, Ray; Holmes, Tom; Cheng, Yung-Sung; Kenoyer, Judson L.; Collins, John W.; Sanderson, T. Ellory; Fliszar, Richard W.; Gold, Kenneth; Beckman, John C.; Long, Julie

2004-10-19

358

Particulates and aerosols characterized in real time for harsh environments using the UMR mobile aerosol sampling system (MASS)  

NASA Astrophysics Data System (ADS)

Over the past 10 years a compact mobile aerosol sampling and characterization facility has been developed and operated by the Cloud and Aerosol Sciences Laboratory at UMR. In this presentation its measurement capabilities which include: total number density, size distribution and hydration property determination in real time for aerosols/particles greater than 0.007 micron, and operational methodology will be described. Its application in harsh environments will be evidenced with data from recent measurement campaigns where the system was used to (1) sample and characterize particulates from the supersonic reacting flow of a high energy chemical laser, (2) detect the presence of an invisible jet engine exhaust plume minutes after the aircraft had passed and discriminate the recently generated jet engine aerosol from ambient background carbonaceous aerosol, and (3) characterize engine and fuel specific aerosol sampled during jet engine testing.

Hagen, Donald E.; Whitefield, Philip D.; Trueblood, Max B.; Lilenfeld, Harvey V.

1993-06-01

359

Trace elements in aerosol particles from Bermuda and Barbados: Concentrations, sources and relationships to aerosol sulfate  

Microsoft Academic Search

The concentrations of selected trace elements and non-sea salt sulfate were determined for aerosol particle samples collected over the open North Atlantic Ocean as part of the Atmosphere\\/Ocean Chemistry Experiment (AEROCE). The concentrations of atmospheric sea salt and mineral aerosol, which together dominate the mass of particulate material in the atmosphere, were higher at Barbados than at Bermuda. In contrast,

R. Arimoto; R. A. Duce; D. L. Savoie; J. M. Prospero

1992-01-01

360

Large-scale aerosol source apportionment in Amazonia  

Microsoft Academic Search

Aerosol particles were collected aboard two Brazilian Bandeirante EMB 110 planes, and the University of Washington Convair C-131A aircraft during the Smoke, Clouds, and Radiation-Brazil (SCAR-B) field project in the Amazon Basin in August and September 1995. Aerosols were collected on Nuclepore and Teflon filters. Aerosol size distribution was measured with a MOUDI cascade impactor. Sampling was performed mostly over

Paulo Artaxo; Eduardo T. Fernandes; José V. Martins; Márcia A. Yamasoe; Peter V. Hobbs; Willy Maenhaut; Karla M. Longo; Andrea Castanho

1998-01-01

361

Characterization and sources assignation of PM2.5 organic aerosol in a rural area of Spain  

NASA Astrophysics Data System (ADS)

The results from a year-long study of the organic composition of PM2.5 aerosol collected in a rural area influenced by a highway of Spain are reported. The lack of prior information related to the organic composition of PM2.5 aerosol in Spain, concretely in rural areas, led definition of the goals of this study. As a result, this work has been able to characterize the main organic components of atmospheric aerosols, including several compounds of SOA, and has conducted a multivariate analysis in order to assign sources of particulate matter. A total of 89 samples were taken between April 2004 and April 2005 using a high-volume sampler. Features and abundance of n-alkanes, polycyclic aromatic hydrocarbons (PAHs), alcohols and acids were separately determined using gas chromatography/mass spectrometry and high performance liquid chromatography analysis. The ? n-alkane and ?PAHs ranged from 3 to 81 ng m -3 and 0.1 to 6 ng m -3 respectively, with higher concentrations during colder months. Ambient concentrations of ?alcohols and ?acids ranged from 21 to 184 ng m -3 and 39 to 733 ng m -3, respectively. Also, several components of secondary organic aerosol have been quantified, confirming the biogenic contribution to ambient aerosol. In addition, factor analysis was used to reveal origin of organic compounds associated to particulate matter. Eight factors were extracted accounting more than 83% of the variability in the original data. These factors were assigned to a typical high pollution episode by anthropogenic particles, crustal material, plant waxes, fossil fuel combustion, temperature, microbiological emissions, SOA and dispersion of pollutants by wind action. Finally, a cluster analysis was used to compare the organic composition between the four seasons.

Pindado, Oscar; Pérez, Rosa M. a.; García, Susana; Sánchez, Miguel; Galán, Pilar; Fernández, Marta

362

Measurement and analysis of aerosol and black carbon in the southwestern United States and Panama and their dependence on air mass origin  

Microsoft Academic Search

Total aerosol mass loading, aerosol absorption, and black carbon (BC) content were determined from aerosol collected on 598 quartz fiber filters at a remote, semiarid site near Orogrande, New Mexico from December 1989 to October 1995. Aerosol mass was determined by weighing filters before and after exposure, and aerosol absorption was determined by measuring the visible light transmitted through loaded

C. Junker; J. N. Sheahan; S. G. Jennings; P. O'Brien; B. D. Hinds; E. Martinez-Twary; A. D. A. Hansen; C. White; D. M. Garvey; R. G. Pinnick

2004-01-01

363

Aerosols in central California: Unexpectedly large contribution of coarse mode to aerosol radiative forcing  

NASA Astrophysics Data System (ADS)

The majority of previous studies dealing with effect of coarse mode aerosols (supermicron) on the radiation budget have focused primarily on regions where total aerosol loadings are substantial. We reexamine this effect for a relatively clean area using a unique 1-month dataset collected during the recent Carbonaceous Aerosol and Radiative Effects Study (CARES, June 2010) in the central California region near Sacramento. Here we define “clean” as aerosol optical depths less than 0.1 at 0.5 ?m. We demonstrate that coarse mode particles contributed substantially (more than 50%) and frequently (up to 85% of time) to the total aerosol volume during this study. In contrast to conventional expectations that the radiative impact of coarse mode aerosols should be small for clean regions, we find that neglecting large particles may lead to significant overestimation, up to 45%, of direct aerosol radiative forcing despite very small aerosol optical depths. Our findings highlight the potential for substantial impacts of coarse mode aerosols on radiative properties over clean areas and the need for more explicit inclusion of coarse mode aerosols in climate-related observational studies.

Kassianov, Evgueni; Pekour, Mikhail; Barnard, James

2012-10-01

364

Global modeling of nitrate and ammonium aerosols using EQSAM3  

NASA Astrophysics Data System (ADS)

Atmospheric aerosols, particles suspending in air, are important as they affect human health, air quality, and visibility as well as climate. Sulfate, nitrate, ammonium, chloride and sodium are among the most important inorganic aerosol species in the atmosphere. These compounds are hygroscopic and absorb water under almost all ambient environmental conditions. The uptake of water alters the aerosol size, and causes water to become the constituent with the largest atmospheric aerosol mass, especially when the aerosols grow into fog, haze or clouds. Furthermore, several global model studies have demonstrated that rapid increases in nitrogen emissions could produce enough nitrate in aerosols to offset the expected decline in sulfate forcing by 2100 for the extreme IPCC A2 scenario (Bauer et al., 2007). Although nitrate and ammonium were identified as significant anthropogenic sources of aerosols by a number of modeling studies, most global aerosol models still exclude ammonium-nitrate when the direct aerosol forcing is studied. In this study, the computationally efficient equilibrium model, EQSAM3, is incorporated into the UMICH-IMPACT-nitrate model using the hybrid dynamical solution method (Feng and Penner, 2007). The partitioning of nitrate and ammonium along with the corresponding water uptake is evaluated by comparing the model to the EQUISOLVE II method used in Feng and Penner (2007). The model is also evaluated by comparison with the AERONET data base and satellite-based aerosol optical depths.

Xu, L.; Penner, J. E.

2009-12-01

365

Source Apportionment of Primary and Secondary Organic Aerosols in Southern California during the 2005 Study of Organic Aerosols in Riverside (SOAR1)  

Microsoft Academic Search

Ambient sampling was conducted in Riverside, California during the 2005 Study of Organic Aerosols in Riverside (SOAR-1) to characterize the composition and sources of organic aerosol using a variety of state-of-the-art instrumentation and source apportionment techniques. The secondary organic aerosol (SOA) mass is estimated by elemental carbon and carbon monoxide tracer methods, water soluble organic carbon content, chemical mass balance

K. D. Docherty; J. L. Jimenez; E. A. Stone; I. M. Ulbrich; P. F. Decarlo; J. J. Schauer; B. Williams; A. H. Goldstein; R. Peltier; R. Weber

2009-01-01

366

Aerosol Chemistry of Furfural and Sugars  

NASA Astrophysics Data System (ADS)

Furfural and sugars (as levoglucosan equivalent) are derived from biomass burning and contribute to aerosol composition. This study examined the potential of furfural and levoglucosan to be tracers of biomass burning. Furfural is likely to be oxidized quickly so comparison with levoglucosan may give a sense of the age of the aerosols in forest fire smoke. However, few furfural emissions are available for biomass combustion. Furfural and sugars were determined in coarse aerosols (>2.4?m aerodynamic diameter) and fine aerosols (<2.4?m aerodynamic diameter) collected in 24 hour periods during different seasons in the United Kingdom and PM10 collected from Thailand and Malaysia including haze episodes. Also total suspended particulate matter (TSP) samples were collected from Taiwan. Furfural and sugars dominated in fine fractions, especially in the UK autumn. Sugars were found at 5.96-18.37 nmol m-3 in fine mode and 1.36-5.75 nmol m-3 in coarse mode aerosols in the UK. Furfural was found at 0.18-0.91 nmol m-3 and 0.05-0.51 nmol m-3 respectively in the same aerosols. Sugars were a dominant contributor to aerosol derived from biomass burning. Sugars and furfural were about 10 and 20 times higher during haze episodes in Malaysia. Laboratory experimental simulation suggested furfural is more rapid destroyed by UV and sunlight than levoglucosan.

Srithawirat, T.; Brimblecombe, P.

2008-12-01

367

Atmospheric Transformations of Chromium Species on Aerosol Nanoparticles  

NASA Astrophysics Data System (ADS)

While nanoparticles can have adverse health effects, the reasons for this toxicity are unclear. One possible reason is that the particles can contain toxic metals such as chromium. Measurements of ambient aerosols in Los Angeles have shown that as particle size decreases, the concentration of chromium increases; chromium (Cr) accounts for up to 10% of the mass of the smallest diameter particles. Chromium exists in two major oxidation states: +3, which is an essential nutrient, and +6, which is highly toxic and carcinogenic. Currently little is known about what happens to the Cr(III)/Cr(VI) ratio in chromium nanoparticles during atmospheric transport. Because the atmosphere is oxidizing in nature, one might think that oxidation of Cr(III) to Cr(VI) would occur in the troposphere. However, there are many other chemical species in aerosol particles which could reduce Cr(VI) to Cr(III). Understanding whether these changes occur in the atmosphere is important because they could alter the toxicity of the particulate matter. The goal of this project is to determine how atmospheric aging of particles affects Cr speciation. To investigate this issue, we collected chromium and chromium/iron particles on Teflon filters from a combustion flame fed with hydrogen, argon, and Cr(CO)5 with and without a source of iron. The samples were cut in half and placed in a solar simulation chamber where they were exposed to sunlight, ozone, water vapor, and, in some cases, basic or acidic conditions. After the aging process, the aged and not aged samples were analyzed for Cr oxidation state using X-ray Absorption Near Edge Spectroscopy (XANES). In particles that had high initial Cr(VI)/Cr(total) ratios, the aging process reduced Cr(VI) by 20%. The Cr(VI)/Cr(total) ratio in fresh particles was reduced by 60% when Fe was added to the flame. Aging of these Cr/Fe particles resulted in an additional 60% reduction in the Cr(VI)/Cr(total) ratio. Particles that had low initial Cr(VI)/Cr(total) ratios experienced no significant change in Cr oxidation states after aging. Although our conditions are simplified relative to the ambient atmosphere, our results suggest that Cr(VI) in ambient nanoparticles is reduced to Cr(III) by atmospheric reactions. In any case, our experiments reveal that atmospheric aging can alter the composition, and therefore the toxicity, of metal-containing aerosol particles.

Werner, M.; Nico, P.; Guo, B.; Kennedy, I.; Anastasio, C.

2003-12-01

368

Estimation of gas-particle partitioning coefficients (Kp) of carcinogenic polycyclic aromatic hydrocarbons in carbonaceous aerosols collected at Chiang-Mai, Bangkok and Hat-Yai, Thailand.  

PubMed

To assess environmental contamination with carcinogens, carbonaceous compounds, water-soluble ionic species and trace gaseous species were identified and quantified every three hours for three days at three different atmospheric layers at the heart of Chiang-Mai, Bangkok and Hat-Yai from December 2006 to February 2007. A DRI Model 2001 Thermal/Optical Carbon Analyzer with the IMPROVE thermal/optical reflectance (TOR) protocol was used to quantify the organic carbon (OC) and elemental carbon (EC) contents in PM10. Diurnal and vertical variability was also carefully investigated. In general, OC and EC mass concentration showed the highest values at the monitoring period of 21.00-00.00 as consequences of human activities at night bazaar coupled with reduction of mixing layer, decreased wind speed and termination of photolysis at nighttime. Morning peaks of carbonaceous compounds were observed during the sampling period of 06:00-09:00, emphasizing the main contribution of traffic emission in the three cities. The estimation of incremental lifetime particulate matter exposure (ILPE) raises concern of high risk of carbonaceous accumulation over workers and residents living close to the observatory sites. The average values of incremental lifetime particulate matter exposure (ILPE) of total carbon at Baiyoke Suit Hotel and Baiyoke Sky Hotel are approximately ten times higher than those air samples collected at Prince of Songkla University Hat-Yai campus corpse incinerator and fish-can manufacturing factory but only slightly higher than those of rice straw burning in Songkla province. This indicates a high risk of developing lung cancer and other respiratory diseases across workers and residents living in high buildings located in Pratunam area. Using knowledge of carbonaceous fractions in PM10, one can estimate the gas-particle partitioning of polycyclic aromatic hydrocarbons (PAHs). Dachs-Eisenreich model highlights the crucial role of adsorption in gas-particle partitioning of low molecular weight PAHs, whereas both absorption and adsorption tend to account for gas-particle partitioning of high molecular weight PAHs in urban residential zones of Thailand. Interestingly, the absorption mode alone plays a minor role in gas-particle partitioning of PAHs in Chiang-Mai, Bangkok and Hat-Yai. PMID:23725158

Pongpiachan, Siwatt; Ho, Kin Fai; Cao, Junji

2013-01-01

369

Aerosol scrubbers  

SciTech Connect

The Submerged Gravel Scrubber is an air cleaning system developed by the Department of Energy's Liquid Metal Reactor Program. The Scrubber System has been patented by the Department of Energy. This technology is being transferred to industry by the DOE. Its basic principles can be adapted for individual applications and the commercialized version can be used to perform a variety of tasks. The gas to be cleaned is percolated through a continuously washed gravel bed. The passage of the gas through the gravel breaks the stream into many small bubbles rising in a turbulent body of water. These conditions allow very highly efficient removal of aerosols from the gas.

Sheely, W.F.

1986-09-09

370

Retrieval of Spectral Aerosol Optical Properties and Their Relationship to Aerosol Chemistry During ARCTAS  

NASA Astrophysics Data System (ADS)

Aerosols are known to both absorb and scatter radiation at UV wavelengths with the degree of absorption/scattering largely dependent on aerosol chemistry. The interactions of aerosols with the UV radiation field were examined during the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS). Analysis focused on two case studies; one flight from the first phase of ARCTAS over Alaska and the Arctic ocean (Flight 10, April 2008) and the other from the second phase over northern Canada (Flight 17, June 2008). These flights were chosen based on availability of aircraft profiles through pollution layers and biomass burning smoke plumes with high loadings of organic aerosol during flight. Aerosol single scattering albedo (?) was retrieved at near-UV (350-400nm) wavelengths at 1nm resolution from spectral actinic flux data collected aboard the NASA DC-8 aircraft during ARCTAS using two CCD Actinic Flux Spectroradiometers. Retrievals were performed using the Tropospheric Ultraviolet Model version 4.6 (TUV 4.6). Inputs of trace gas (e.g., NO2, SO2) concentrations, aerosol optical depth, location, time, pressure, etc. required by TUV were determined from ancillary aircraft measurements made from the DC-8. Values of ? were subsequently used to determine absorption optical depth (?abs) for each of the examined flights. Retrieval and calculation results were compared to aerosol optical properties in the visible (calculated from measurements of absorption and scattering aboard the DC-8) and the spectral dependencies characterized. Spectral ? and ?abs were compared with aerosol chemistry data collected by an Aerosol Mass Spectrometer (AMS) to provide insight into the role of aerosol composition on absorption in the UV wavelength range. In particular, spectral dependencies were compared to the oxidation state of the organic aerosol (determined from AMS data) to examine the impact of aerosol processing/aging on spectral ? and ?abs.

Corr, C. A.; Hall, S. R.; Ullmann, K.; Shetter, R.; Anderson, B. E.; Beyersdorf, A. J.; Thornhill, K. L.; Cubison, M.; Jimenez, J. L.; Dibb, J. E.

2010-12-01

371

Characterization of high-resolution aerosol mass spectra of primary organic aerosol emissions from Chinese cooking and biomass burning  

NASA Astrophysics Data System (ADS)

Aerosol mass spectrometry has proved to be a powerful tool to measure submicron particulate composition with high time resolution. Factor analysis of mass spectra (MS) collected worldwide by aerosol mass spectrometer (AMS) demonstrates that submicron organic aerosol (OA) is usually composed of several major components, such as oxygenated (OOA), hydrocarbon-like (HOA), biomass burning (BBOA), and other primary OA. In order to help interpretation of component MS from factor analysis of ambient OA datasets, AMS measurements of different primary sources is required for comparison. Such work, however, has been very scarce in the literature, especially for high resolution MS (HR-MS) measurements, which performs improved characterization by separating the ions of different elemental composition at each m/z in comparison with unit mass resolution MS (UMR-MS) measurements. In this study, primary emissions from four types of Chinese cooking (CC) and six types of biomass burning (BB) were simulated systematically and measured using an Aerodyne High-Resolution Time-of-Flight AMS (HR-ToF-AMS). The MS of the CC emissions show high similarity, with m/z 41 and m/z 55 being the highest signals; the MS of the BB emissions also show high similarity, with m/z 29 and m/z 43 being the highest signals. The MS difference between the CC and BB emissions is much bigger than that between different CC (or BB) types, especially for the HR-MS. The O/C ratio of OA ranges from 0.08 to 0.13 for the CC emissions and from 0.18 to 0.26 for the BB emissions. The UMR ions of m/z 43, m/z 44, m/z 57, and m/z 60, usually used as tracers in AMS measurements, were examined for their HR-MS characteristics in the CC and BB emissions. In addition, the MS of the CC and BB emissions are also compared with component MS from factor analysis of ambient OA datasets observed in China, as well as with other AMS measurements of primary sources in the literature. The MS signatures of cooking and biomass burning emissions revealed in this study can be used as important reference for factor analysis of ambient OA datasets, especially for the relevant studies in East Asia.

He, L.-Y.; Lin, Y.; Huang, X.-F.; Guo, S.; Xue, L.; Su, Q.; Hu, M.; Luan, S.-J.; Zhang, Y.-H.

2010-12-01

372

Aerosol Chemical Composition and its Effects on Cloud-Aerosol Interactions during the 2007 CHAPS Experiment  

NASA Astrophysics Data System (ADS)

Chemical composition of submicron aerosol particles was determined using an Aerodyne Time-of-Flight Aerosol Mass Spectrometer (AMS) outfitted on the DOE G-1 aircraft during the Cumulus Humilis Aerosol Processing Study (CHAPS) conducted in Oklahoma City area in June 2007. The primary objective of CHAPS was to investigate the effects of urban emissions on cloud aerosol interactions as a function of processing of the emissions. Aerosol composition was typically determined at three different altitudes: below, in, and above cloud, in both upwind and downwind regions of the urban area. Aerosols were sampled from an isokinetic inlet with an upper size cut-off of ~1.5 micrometer. During cloud passages, the AMS also sampled particles that were dried from cloud droplets collected using a counter-flow virtual impactor (CVI) sampler. The aerosol mass concentrations were typically below 10 microgram per cubic meter, and were dominated by organics and sulfate. Ammonium was often less than required for complete neutralization of sulfate. Aerosol nitrate levels were very low. We noted that nitrate levels were significantly enhanced in cloud droplets compared to aerosols, most likely resulting from dissolution of gaseous nitric acid. Organic to sulfate ratios appeared to be lower in cloud droplets than in aerosols, suggesting cloud condensation nuclei properties of aerosol particles might be affected by loading and nature of the organic components in aerosols. In-cloud formation of sulfate was considered unimportant because of the very low SO2 concentration in the region. A detailed examination of the sources of the aerosol organic components (based on hydrocarbons determined using a proton transfer reaction mass spectrometer) and their effects on cloud formation as a function of atmospheric processing (based on the degree of oxidation of the organic components) will be presented.

Lee, Y.; Alexander, L.; Newburn, M.; Jayne, J.; Hubbe, J.; Springston, S.; Senum, G.; Andrews, B.; Ogren, J.; Kleinman, L.; Daum, P.; Berg, L.; Berkowitz, C.

2007-12-01

373

Carbonaceous aerosols at urban influenced sites in Norway  

Microsoft Academic Search

Little is known regarding levels and source strength of carbonaceous aerosols in Scandinavia. In the present study, ambient aerosol (PM10 and PM2.5) concentrations of elemental carbon (EC), organic carbon (OC), water-insoluble organic carbon (WINSOC), and water-soluble organic carbon (WSOC) are reported for a curbside site, an urban background site, and a suburban site in Norway in order to investigate their

K. E. Yttri; C. Dye; O.-A. Braathen; D. Simpson; E. Steinnes

2008-01-01

374

Detection and quantification of levoglucosan in atmospheric aerosols: a review  

Microsoft Academic Search

Levoglucosan is a tracer for biomass burning sources in atmospheric aerosol particles. Therefore, much effort has been recently\\u000a put into developing methods for its quantification. This review describes and compares both established and emerging analytical\\u000a methods for levoglucosan quantification in ambient aerosol samples, with the special needs of the environmental analytical\\u000a chemist in mind.

Gal Schkolnik; Yinon Rudich

2006-01-01

375

Comparison of measurements of aerosol elemental carbon at Wrangel Island, USSR, and Barrow, Alaska.  

National Technical Information Service (NTIS)

During the winter and spring seasons of 1989 and 1990, we collected samples of the background aerosol at Wrangel Island in the eastern Soviet Arctic. The samples were analyzed by optical transmission to determine the concentration of aerosol ''black'' car...

A. V. Polissar V. N. Kapustin A. D. A. Hansen

1991-01-01

376

Characteristics of Natural - and Brush Fire Atmospheric Aerosols of the Amazon Basin.  

National Technical Information Service (NTIS)

The experiments described concern the air particulate matter component of the 'Projeto Queimadas'. (Brushfire Project) Samplings have been done in the North (natural aerosols) and southwest (brushfire aerosols) of the city of Manaus. Collected samples hav...

P. E. Artaxo Netto C. M. Q. Orsini M. H. Tabacniks L. C. S. Boueres A. Leslie

1981-01-01

377

Comparison of Lab Pack and Bulk Disposal of Aerosols in HHW Programs.  

National Technical Information Service (NTIS)

Aerosol cans containing various products are one of the largest categories of waste brought to Household Hazardous Waste (HHW) Collection Programs in the United States. Although the disposal of aerosol products and their containers may not represent one o...

W. Turner

1993-01-01

378

Characterization of Ice Nuclei in the Arctic during the Indirect Semi-Direct Aerosol Campaign (ISDAC)  

NASA Astrophysics Data System (ADS)

Aerosols are important in Polar Regions since they act as nucleation sites for ice crystal growth and cold cloud formation. Aerosol-cloud interactions are not well understood especially in the mixed phase and fully glaciated clouds found in the polar atmosphere. Previous measurements of ice nuclei (IN) concentrations in the Arctic have shown a large variation spatially and seasonally. This presentation will investigate and characterize IN concentrations in the Arctic Spring from the Indirect Semi-Direct Aerosol Campaign (ISDAC), as measured by the Texas A&M Continuous Flow Diffusion Chamber (CFDC). ISDAC measurements were conducted in April 2008, with instrumented aircraft sorties in the vicinity of the ARM Climate research Facility (ACRF) in Barrow, Alaska. During this campaign the CFDC measured IN concentrations both in and out of stratiform mixed phase and glaciated clouds. Over the ISDAC experimental period the CFDC operated within a temperature range of -10°C to -35°C and a range of supersaturations with respect to ice of 0 to 40 %. Observed IN concentrations ranged from 0.1 L-1 to as high as ? 20 L-1, in extreme cases. One of the flights during the ISDAC campaign was used to investigate the threshold temperature required to initiate homogeneous freezing of ambient aerosol. The conditions, limitations and variability of the CFDC measurements will be discussed. In addition, the sources and trajectories of the aerosols acting as IN will be determined. The IN concentration results from the field campaign will be compared to similar measurements collected in the spring season during the Surface Heat Budget of the Arctic (SHEBA) campaign in 1998, and the fall season during the Mixed-Phase Arctic Cloud Experiment (MPACE) in 2004.

Glen, A.; Brooks, S. D.; Liu, P.; MacDonald, A.

2009-12-01

379

Carbonaceous aerosols at urban influenced sites in Norway  

NASA Astrophysics Data System (ADS)

Little is known regarding levels and source strength of carbonaceous aerosols in Scandinavia. In the present study, ambient aerosol (PM10 and PM2.5) concentrations of elemental carbon (EC), organic carbon (OC), water-insoluble organic carbon (WINSOC), and water-soluble organic carbon (WSOC) are reported for a curbside site, an urban background site, and a suburban site in Norway in order to investigate their spatial and seasonal variations. Aerosol filter samples were collected using tandem filter sampling to correct for the positive sampling artefact introduced by semi volatile OC. Analyses were performed using the thermal optical transmission (TOT) instrument from Sunset Lab Inc., which corrects for charring during analysis. Finally, we estimated the relative contribution of OC from wood burning based on the samples content of levoglucosan. Levels of EC varied by more than one order of magnitude between sites, likely due to the higher impact of vehicular traffic at the curbside and the urban background sites. In winter, the level of particulate organic carbon (OCp) at the suburban site was equal to (for PM10) or even higher (for PM2.5) than the levels observed at the curbside and the urban background sites. This finding was attributed to the impact of residential wood burning at the suburban site in winter, which was confirmed by a high mean concentration of levoglucosan (407 ng m-3). This finding indicates that exposure to primary combustion derived OCp could be equally high in residential areas as in a city center. It is demonstrated that OCp from wood burning (OCwood) accounted for almost all OCp at the suburban site in winter, allowing a new estimate of the ratio TCp/levoglucosan for both PM10 and PM2.5. Particulate carbonaceous material (PCM = Organic matter + Elemental matter) accounted for 46 83% of PM10 at the sites studied when considering the positive artefact of semi volatile OC, thus being the major contributor to PM.

Yttri, K. E.; Dye, C.; Braathen, O.-A.; Simpson, D.; Steinnes, E.

2008-11-01

380