Published 2016
| Version v1
Publication
Brown carbon and thermal-optical analysis: A correction based onoptical multi-wavelength apportionment of atmospheric aerosols
Contributors
Description
Thermo-optical analysis is widely adopted for the quantitative determination of total, TC, organic, OC and
elemental, EC, Carbon in aerosol samples collected on quartz fibre filters. Nevertheless, the methodology
presents several issues in particular about the artefacts related to the formation of pyrolytic carbon. It is
usually neglected the uncertainty due to the possible presence of brown carbon (BrC) in the sample
under analysis, i.e. the optically active fraction of OC produced by biomass burning and with characteristics
intermediate between OC and EC. We introduce here a novel correction to the standard thermooptical
protocol based on the determination of the fraction of the sample absorbance due to the
(possible) presence of BrC. This is achievable thanks to the coupled use of the Multi Wavelength
Absorbance Analyser (MWAA) of the University of Genoa and a standard Sunset Inc. EC/OC analyser. Our
correction provides a firmer OC/EC separation as well as an operative quantification of the BrC mass. The
methodology has been validated against independent determination of the levoglucosan content in the
same filters sent to the Sunset analysis. Corrections up to 23% in the OC and EC values, determined via the
standard and new thermo-optical analysis, have been found in a set of PM10 (i.e. Particulate Matter with
aerodynamic diameter less than 10 mm) samples collected wintertime at a mountain site in Northern
Italy.
Additional details
Identifiers
- URL
- http://hdl.handle.net/11567/817030
- URN
- urn:oai:iris.unige.it:11567/817030