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Derivation of the Density and Refractive Index of Organic Matter and Elemental Carbon from Closure between Physical and Chemical Aerosol Properties

Schmid, Otmar; Chand, Duli; Karg, Erwin; Guyon, Pascal; Frank, Göran LU ; Swietlicki, Erik LU and Andreae, Meinrat O. (2009) In Environmental Science & Technology 43(4). p.1166-1172
Abstract
Information on the density (p) and refractive index m(=n-ik) of elemental carbon (ECa) and organic matter (OMa), the main carbon components of atmospheric aerosols, has frequently been obtained from closure calculations between physical and chemical aerosol properties. However, this approach has suffered from large uncertainties since there were more unknown (or poorly known) parameters than defining equations. In this study, we propose a method that avoids this ambiguity mainly by considering both optical and mass closure and by expressing the three ECa parameters (p(Eca), n(Eca), k(ECa)) by a single (unknown) parameter. This allows mathematically rigorous determination of p(Eca), m(Eca), p(OMa) and m(OMa) from standard physico-chemical... (More)
Information on the density (p) and refractive index m(=n-ik) of elemental carbon (ECa) and organic matter (OMa), the main carbon components of atmospheric aerosols, has frequently been obtained from closure calculations between physical and chemical aerosol properties. However, this approach has suffered from large uncertainties since there were more unknown (or poorly known) parameters than defining equations. In this study, we propose a method that avoids this ambiguity mainly by considering both optical and mass closure and by expressing the three ECa parameters (p(Eca), n(Eca), k(ECa)) by a single (unknown) parameter. This allows mathematically rigorous determination of p(Eca), m(Eca), p(OMa) and m(OMa) from standard physico-chemical aerosol data and rigorous error analysis. The results are unambiguous and self-consistent, i.e., there is no difference between the chemically and physically derived p and m values of the atmospheric aerosol. Application of this method to our previously published data on biomass burning particles from Amazonia yields p(Eca) = 1.8(+/- 0.2) g/cm(3), m(ECa) = 1.9(+/- 0.1)-i0.20(-0.04/+0.02), p(OMa) = 1.39(+/- 0.13) g/cm(3) and m(OMa)=1.46(+/- 0.02), where the 1 sigma uncertainty limits given in parenthesis are based on the principles of error propagation. The relatively low imaginary part of mEca indicates the presence of only partially graphitized elemental carbon, which is consistent with biomass burning aerosol dominated bysmoldering combustion conditions. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Environmental Science & Technology
volume
43
issue
4
pages
1166 - 1172
publisher
The American Chemical Society
external identifiers
  • wos:000263298600035
  • scopus:64349096429
ISSN
1520-5851
DOI
10.1021/es800570p
language
English
LU publication?
yes
id
c29e726e-99c8-4bad-8170-6f44689640e8 (old id 1375026)
date added to LUP
2009-05-08 13:27:09
date last changed
2017-01-15 04:00:44
@article{c29e726e-99c8-4bad-8170-6f44689640e8,
  abstract     = {Information on the density (p) and refractive index m(=n-ik) of elemental carbon (ECa) and organic matter (OMa), the main carbon components of atmospheric aerosols, has frequently been obtained from closure calculations between physical and chemical aerosol properties. However, this approach has suffered from large uncertainties since there were more unknown (or poorly known) parameters than defining equations. In this study, we propose a method that avoids this ambiguity mainly by considering both optical and mass closure and by expressing the three ECa parameters (p(Eca), n(Eca), k(ECa)) by a single (unknown) parameter. This allows mathematically rigorous determination of p(Eca), m(Eca), p(OMa) and m(OMa) from standard physico-chemical aerosol data and rigorous error analysis. The results are unambiguous and self-consistent, i.e., there is no difference between the chemically and physically derived p and m values of the atmospheric aerosol. Application of this method to our previously published data on biomass burning particles from Amazonia yields p(Eca) = 1.8(+/- 0.2) g/cm(3), m(ECa) = 1.9(+/- 0.1)-i0.20(-0.04/+0.02), p(OMa) = 1.39(+/- 0.13) g/cm(3) and m(OMa)=1.46(+/- 0.02), where the 1 sigma uncertainty limits given in parenthesis are based on the principles of error propagation. The relatively low imaginary part of mEca indicates the presence of only partially graphitized elemental carbon, which is consistent with biomass burning aerosol dominated bysmoldering combustion conditions.},
  author       = {Schmid, Otmar and Chand, Duli and Karg, Erwin and Guyon, Pascal and Frank, Göran and Swietlicki, Erik and Andreae, Meinrat O.},
  issn         = {1520-5851},
  language     = {eng},
  number       = {4},
  pages        = {1166--1172},
  publisher    = {The American Chemical Society},
  series       = {Environmental Science & Technology},
  title        = {Derivation of the Density and Refractive Index of Organic Matter and Elemental Carbon from Closure between Physical and Chemical Aerosol Properties},
  url          = {http://dx.doi.org/10.1021/es800570p},
  volume       = {43},
  year         = {2009},
}