Bulletin of the American Physical Society
2008 APS March Meeting
Volume 53, Number 2
Monday–Friday, March 10–14, 2008; New Orleans, Louisiana
Session S26: Focus Session: Advances in Atmospheric Aerosol Science I |
Hide Abstracts |
Sponsoring Units: DCP Chair: Kevin Wilson, Lawrence Berkely National Laboratory Room: Morial Convention Center 218 |
Wednesday, March 12, 2008 2:30PM - 3:06PM |
S26.00001: Tropopsheric Aerosol Chemistry via Aerosol Mass Spectrometry Invited Speaker: A broad overview of size resolved aerosol chemistry in urban, rural and remote regions is evolving from deployment of aerosol mass spectrometers (AMS) throughout the northern hemisphere. Using thermal vaporization and electron impact ionization as universal detector of non-refractory inorganic and organic composition, the accumulation of AMS results represent a library of mass spectral signatures of aerosol chemistry. For organics in particular, mass spectral factor analysis provides a procedure for classifying (and simplifying) complex mixtures composed of the hundreds or thousands of individual compounds. Correlations with parallel gas and aerosol measurements (e.g. GC/MS, HNMR, FTIR) supply additional chemical information needed to interpret mass spectra. The challenge is to separate primary and secondary; anthropogenic, biogenic and biomass burning sources - and subsequent - transformations of aerosol chemistry and microphysics. [Preview Abstract] |
Wednesday, March 12, 2008 3:06PM - 3:42PM |
S26.00002: The Dynamic Interaction of Chemistry and Phase Partitioning in Atmospheric Organic Aerosols Invited Speaker: Atmospheric organic aerosols are a dynamic, chemically evolving mixture in equilibrium between the gas and condensed phases. This applies equally to primary emissions, which span a huge range in volatility, as well as secondary oxidation products generated by chemical reactions in both phases. The degree of volatility of primary emissions has been historically underappreciated, and the role of oxidation reactions has been considered in almost all cases only through their first one or two generations. We have recently developed a `volatility basis set' to address both primary volatility distributions and secondary volatility evolution (sometimes called primary organic aerosol and secondary organic aerosol). Here we shall discuss both facets of this framework as they apply to problems in organic aerosols on all scales, from emissions measurements to global organic aerosol loadings. We shall describe ongoing experimental work to constrain volatility distributions and volatility evolution through chemistry as well as extensions to the basis-set framework to more fully describe evolving aerosol properties. [Preview Abstract] |
Wednesday, March 12, 2008 3:42PM - 3:54PM |
S26.00003: Tandem mass spectrometry of single organic aerosol particles: A promising approach for in-situ analysis of mixtures. Pedro Campuzano Jost, Sarah Hanna, Emily Simpson, Damon Robb, Michael Blades, John Hepburn, Allan Bertram We have built a new single particle mass spectrometer for organic aerosol analysis that combines different previously tried approaches into one single instrument. We use soft, wavelength tunable desorption by using a dedicated pulsed CO$_{2}$ laser, (Prather, Baer {\&} coworkers) and soft ionization by tunable VUV radiation (Baer, Wilson {\&} coworkers)) to ensure a minimum of fragmentation. By ionizing the aerosol plume in the center of an ion trap both high sensitivity and the ability to elucidate structure by tandem mass spectrometry (Reilly {\&} coworkers) can be achieved. The analytical performance of the instrument as well as the detection geometry has first been validated by using simpler ionization techniques, 70 eV EI and REMPI, on a suite of aromatic and aliphatic compounds and simple mixtures. The novel tunable VUV laser system has been thoroughly characterized with a host of gaseous organic compounds that has proven both the ability to determine ionization energies with high accuracy and the possibility in many cases to minimize fragmentation by tuning the VUV source close to the ionization threshold. The VUV source has been integrated into the aerosol mass spectrometer and first VUV single aerosol spectra will be presented. [Preview Abstract] |
Wednesday, March 12, 2008 3:54PM - 4:06PM |
S26.00004: A novel flow reactor for studying the hydrolysis of N$_2$O$_5$ on aqueous H$_2$SO$_4$ solutions coated with organic surfactants Daniel Knopf, Lori Cosman, Allan Bertram, Payam Mousavi, Satya Mokamati A flow reactor has been developed which allows the study of heterogeneous kinetics on an aqueous surface coated by organic monolayers. Computational fluid dynamics simulations have been used to determine the flow characteristics for various experimental conditions. A mathematical framework has been developed to derive the true first order wall loss rate coefficient from the experimentally observed wall loss rate. Validation of the flow reactor was performed by measuring reactive uptake coefficients of well studied systems as a function of flow velocity and pressure. We determined the reactive uptake of N$_2$O$_5$ on aqueous H$_2$SO$_4$ solutions coated with a monolayer of 1-octadecanol, 1-hexadecanol, stearic acid, and phytanic acid. The reactive uptake decreased by approximately a factor of 17--61 in the presence of insoluble, straight-chain organic monolayers compared to uncoated solutions. However, the branched monolayer (phytanic acid) did not significantly affect the N$_2$O$_5$ uptake. The reactive uptake coefficients measured on aqueous H$_2$SO$_4$ subphases show a relationship to the surface area occupied by the surfactant molecules. However, data obtained with other subphases do not overlap with this trend. [Preview Abstract] |
Wednesday, March 12, 2008 4:06PM - 4:18PM |
S26.00005: Spectromicroscopic Studies of the Aging of Carbonaceous Aerosols from Mexico City Ryan Moffet, Yury Desyaterik, Alexi Tivanski, Rebecca Hopkins, Jerome Fast, James Barnard, Alexander Laskin, Mary Gilles Milagro, a multi-national atmospheric field campaign, was conducted in Mexico City during March of 2006. Aerosols were collected at three ground based sites, situated progressively farther from the city center. These aerosol samples are studied with computer controlled scanning electron microscopy with energy dispersive X-ray analysis (CCSEM/EDX) and scanning transmission x-ray microscopy with near edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS). This presentation focuses on evidence for carbonaceous aerosol transformation examining aerosol composition, C/O atomic ratios, mixing states, and changes in carbon bonding over time and distance from the source. [Preview Abstract] |
Wednesday, March 12, 2008 4:18PM - 4:54PM |
S26.00006: A connection between arctic haze and halogen chemistry? Invited Speaker: It has long been known that the Arctic spring time exhibits a phenomenon known as ``Arctic Haze'', characterized by low visibilities, caused by a relatively high concentration of fine aerosol. This aerosol is known to be composed largely of sulfate, with the precursor SO$_{2}$ transported from anthropogenic sources regions in North America and Eurasia. However, since the original studies of Arctic Haze, a complex array of halogen chemistry (involving Cl, Br and I chemistry), initiated by chemistry and photochemistry on frozen saline surfaces and in sea salt aerosol, has been discovered. That halogen chemistry makes the Arctic boundary layer extremely oxidizing, with large concentrations of both halogen radicals and HO$_{x}$. That environment can lead to new particle production via oxidation of organic gas phase precursors and/or enhanced oxidation of SO$_{2}$. Recent observations of a rapidly changing surface in the Arctic raise questions about how this halogen chemistry, which also which results in massive scale depletion of ozone and mercury, will change in the future. In this talk I will discuss what is known about halogen chemistry in polar regions, how that ties to aerosol chemistry, and how these are impacted by climate change and changes in the nature of the frozen surface. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700