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CHEMICAL COMPOSUTION OF ORGANIC AEROSOL EXPLORED BY TD-PTR-MS Rupert Holzinger, Joseph Timkovsky, Beatriz Oyama, Niels van Elst, Patrick Schlag, Ulrike Dusek Institute for Marine and Atmospheric Research (IMAU), Utrecht University, Netherlands
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Outline The TD-PTR-MS instrument Field Campaigns, Cabauw & CalNex Organic Aerosol (OA) on Filter Samples Urban OA in Sao Paulo, Brazil OA across the Atlantic Ocean
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The TD-PTR-MS: (Thermal-desorption Proton-transfer- reaction Mass-spectrometer) * Sensitivity * * Quantitative * * detects large fraction of organics *
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Operation at the LA site, May 15 – June 15, 2010. Los Angeles Field Studies: Calnex & Cabauw © KNMI
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Operation in the field Cycling repeated every 90 min Aerosols background every other run
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Hundreds of organic (and a few inorganic) aerosol species are typically detected
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Example timelines, different thermograms
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Comparison with AMS at Cabauw, 2012 Good correlation between PTR-MS and ToF-AMS (r 2 =0.77), but PTR-MS only sees ~10-20 % of ToF-AMS mass: Was also seen in previous campaigns (~ 30 % compared to AMS in 2008 and 2009) PTR-MS had a bad MCP and could not measure masses > 250 properly
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Comparison with AMS during CalNex
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Correlation with OA-coponents (AMS-PMF), CalNex 2010
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Results Correlation Analysis AMSPTR OA100160 HOA-ions1647 LVOOA-ions2264 Nitrogen concentration [ng/m3]: SV-OOA rejuvenating during daytime! More Nitrogen than expected.
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Organic Aerosol (OA) on Filter Samples Organic Aerosol on Filter Samples
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561011121315 Cabauw, NL, Feb/March 2011 Filter & In Situ
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The comparison of in situ and filter measurements of aerosols with PTR-MS Points: background is subtracted; masses are binned into groups, binsize is 20 Da; data for the temperature range 150-350C are summed up 1-day filters2-day filters3-day filters
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OA study in Sao Paulo, Brazil Janio Quadros Tunnel – inside the city LIGHT FLEET Rodoanel Tunnel – outside the city HEAVY FLEET Institute of Astronomy, Geophysics and Atmospheric Sciences University of Sao Paulo
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Source signatures
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Ambient OA, Sao Paulo, Brazil
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OA during S/N Atlantic transect April/May 2010
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163 masses found Analysis of the Europe plume with the NH as background signal
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Analysis of the NH background with the SH as background signal 7 ions found
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Analysis of the SH Plume with the SH as background signal 355 ions found
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Conclusions TD-PTR-MS is a strong analytical tool, complementary to other techniques. Surprising findings: (i) Rejuvenation of OA during daytime, (ii) high Nitrogen content Reasonable agreement with AMS, SMPS etc. Analysis of filter samples provides new opportunities Acknowledgements Funding: ACTRIS, NOW, NSF Thanks to colleagues from: University of Sao Paulo, Brazil; Univesity of California at Berkeley, University of Colorado, USA; Polarstern, Forschungszentrum Jülich, Germany; CESAR consortium, Netherlands.
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Example for aerosol background: Inlet A sampled ambient air Inlet B sampled ambient air through Teflon filter
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