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| Titel |
Characterization of trace metals on soot aerosol particles with the SP-AMS: detection and quantification |
| VerfasserIn |
S. Carbone, T. Onasch, S. Saarikoski, H. Timonen, K. Saarnio, D. Sueper, T. Rönkkö, L. Pirjola, A. Häyrinen, D. Worsnop, R. Hillamo |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 8, no. 11 ; Nr. 8, no. 11 (2015-11-18), S.4803-4815 |
| Datensatznummer |
250116685
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| Publikation (Nr.) |
 copernicus.org/amt-8-4803-2015.pdf |
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| Zusammenfassung |
| A method to detect and quantify mass concentrations of trace metals on soot
particles by the Aerodyne soot-particle aerosol mass spectrometer
(SP-AMS) was developed and evaluated in this study. The generation of
monodisperse Regal black (RB) test particles with trace amounts of 13
different metals (Na, Al, Ca, V, Cr, Mn, Fe, Ni, Cu, Zn, Rb, Sr and Ba)
allowed for the determination of the relative ionization efficiency of each
metal relative to black carbon (RIEmeas). The observed
RIEmeas / RIEtheory values were larger than unity for Na, Rb, Ca, Sr
and Ba due to thermal surface ionization (TSI) on the surface of the
laser-heated RB particles. Values closer to unity were obtained for the
transition metals Zn, Cu, V and Cr. Mn, Fe, and Ni presented the lowest
RIEmeas / RIEtheory ratios and highest deviation from unity. The
latter discrepancy is unexplained; however it may be related to problems with
our calibration method and/or the formation of metal complexes that were not
successfully quantified. The response of the metals to the laser power was
investigated and the results indicated that a minimum pump laser current of
0.6 A was needed in order to vaporize the metals and the refractory black carbon (rBC). Isotopic
patterns of metals were resolved from high-resolution mass spectra, and the
mass-weighted size distributions for each individual metal ion were obtained
using the high-resolution particle time-of-flight (HR-PToF) method. The
RIEmeas values obtained in this study were applied to the data of
emission measurements in a heavy-fuel-oil-fired heating station. Emission
measurements revealed a large number of trace metals, including evidence for
metal oxides and metallic salts, such as vanadium sulfate, calcium sulfate,
iron sulfate and barium sulfate, which were identified in the SP-AMS
high-resolution mass spectra. SP-AMS measurements of Ba, Fe, and V agreed
with ICP-MS analyzed filter samples within a factor of 2 when emitted rBC
mass loadings were elevated. |
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