Hannover 2016 – scientific programme

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MS: Fachverband Massenspektrometrie

MS 7: Accelerator Mass Spectrometry and Applications I

MS 7.5: Talk

Thursday, March 3, 2016, 12:15–12:30, f128

Online coupling of thermal-optical and 14C AMS analysis in atmospheric aerosols source apportionment — •Sönke Szidat, Konstantinos Agrios, and Gary Salazar — Universität Bern, Departement für Chemie und Biochemie & Oeschger-Zentrum für Klima- und Klimafolgenforschung, Bern, Schweiz

Radiocarbon (14C) is a powerful tool that allows the distinction of fossil and non-fossil sources of atmospheric carbonaceous aerosols. The total carbon fraction and its sub-fractions organic carbon (OC) and elemental carbon (EC) comprise a significant portion of the atmospheric fine air particulate matter, influencing the global climate and human health. The separation of OC and EC for 14C measurement is performed with a commercial thermo-optical aerosol analyzer that transforms thermal degradation products into gaseous carbon dioxide. Currently, these gas fractions are then analyzed for 14C with the accelerator mass spectrometry (AMS) system MICADAS either offline (i.e. by sealing of ampules) or by trapping with a zeolite molecular sieve and direct transfer. Although these techniques have been frequently applied with success, they suffer from a loss of information by mixing, as both fractions, OC and EC, comprise many individual chemical compounds. Therefore, we present here the development of a continuous-flow AMS analytical hyphenation. This approach allows for real-time 14C AMS analysis of carbonaceous aerosol samples, as they evolve sequentially from the thermo-optical aerosol analyzer according to their volatility and refractivity.