1 / 13

U. Dusek 1 , R. Holzinger 1 , T. Röckmann 1

Combined measurements of organic aerosol isotopic and chemical composition – A day/night test case. U. Dusek 1 , R. Holzinger 1 , T. Röckmann 1 Institute for Marine and Atmospheric research Utrecht (IMAU),
Utrecht University, The Netherlands. ORGANIC AEROSOL CHARACTERIZATION.

tucker
Download Presentation

U. Dusek 1 , R. Holzinger 1 , T. Röckmann 1

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Combined measurements of organic aerosol isotopic and chemical composition – A day/night test case U. Dusek1, R. Holzinger1, T. Röckmann1 Institute for Marine and Atmospheric research Utrecht (IMAU),
Utrecht University, The Netherlands

  2. ORGANIC AEROSOL CHARACTERIZATION Combination of 3 relatively new techniques: 14C: fossil (no 14C) vs. non-fossil sources 13C: ? might give indication of aerosol processing and/or sources Thermal desorption PTR-MS: detailed chemical composition • High volume filter samples: • 500 l/min • separate filters during day and night • each loaded for 2-3 days Apply to aerosol filter samples taken in Cabauw, NL during Pegasos

  3. 14C for source apportionment 14C: radioactive isotope, continuously replenished in the atmosphere fm ~ 1.04 fm = 1.1 - 1.2 fm = 0 Biomass burning Fossil fuel Biogenic 14C Measured on OC, EC, TC, WIOC using extraction technique developed at IMAU

  4. 13C indicator of aerosol processing? Photochemical aging: Oxidation by O3, OH Loss of OC Gas phase formation of SV products: If gas phase precursors are partially reacted 12C pref. reacted to SV Products Lower d13C 12C pref. reacted away Remaining carbon: Higher d13C 12C 13C (~ 1%) More reactive Less reactive Higher vapor pressure Lower vapor pressure R=13C/12C 2 stable carbon isotopes -values: (Rx -Rst)/Rst*1000

  5. 13C and chemical measurement setup IRMS Catalysts Oven 1 Oven 2 50-450°C 500°C Remove H2O Liquid N2 Isotope measurement PTR-MS CO2 is frozen and later released to be analyzed for isotopic composition High resolution mass spectrometry of largely unfragmented compounds

  6. 2 cases 1) 24 - 27 MAY: Aged cont. case Warm Sunny dry Night: stable stratification low inversion layer 2) 1-3 JUNE: Recent pollution case cool sunny Night: stable stratification low inversion layer

  7. Fossil and contemporary carbon in day and night contemporary OC concentration enhanced in the night

  8. OC thermogram Aged cont. case Semi-volatile organics enhanced Low volatile organics little change

  9. d13C thermogram Aged cont. case Recent poll case Consistent with partitioning: gas phase: d13C low particle phase: d13C high condensation lowers particle d13C • Other effects must play a role: • Change in sources? • day-time photochemistry? • Recent SOA?

  10. PTR-MS first results OC night / OC day Lighter molecules preferentially enhanced during night time

  11. Summary • Carbonaceous aerosol has higher fraction of contemporary carbon during night • Mainly increase in contemporary OC, with small decrease in fossil OC and EC Oven 1 Oven 2 • Semi-volatile carbon is enhanced during night time 50-450°C 500°C IRMS • Semi-volatile carbon depleted in d13C compared to low-volatile (less aged?) • Day-night change only at oven T=150 °C • Compounds with smaller mass more strongly enhanced during the night

  12. Outook IRMS • Investigate isotopic effects of partitioning / photochemical aging in the lab • Study source signatures • Fall and winter studies • Are O:C and H:C ratios higher during the night? • Do any particular chemical compounds show a strong day/night difference (tracers?)

  13. Outook Thanks for your attention • B. Oyama, W. Ramon, P.A. de Wilde • Grants: • NWO grant number 820.01.001 • ALW-­‐Middelgroot program (Grant 834.08.002)

More Related