Article

Journal of Atmospheric Chemistry

, Volume 22, Issue 1, pp 19-39

First online:

Trace elements in tropical African savanna biomass burning aerosols

  • A. GaudichetAffiliated withUnité de Physico-chimie et Géochimie de l'Atmosphère, UA-CNRS 1404 Universités Paris VII-Paris XII
  • , F. EchalarAffiliated withUnité de Physico-chimie et Géochimie de l'Atmosphère, UA-CNRS 1404 Universités Paris VII-Paris XII
  • , B. ChatenetAffiliated withUnité de Physico-chimie et Géochimie de l'Atmosphère, UA-CNRS 1404 Universités Paris VII-Paris XII
  • , J. P. QuisefitAffiliated withUnité de Physico-chimie et Géochimie de l'Atmosphère, UA-CNRS 1404 Universités Paris VII-Paris XII
  • , G. MalingreAffiliated withUnité de Physico-chimie et Géochimie de l'Atmosphère, UA-CNRS 1404 Universités Paris VII-Paris XII
  • , H. CachierAffiliated withCentre des Faibles Radioactivités, CNRS-CEA
  • , P. Buat-MenardAffiliated withCentre des Faibles Radioactivités, CNRS-CEA
  • , P. ArtaxoAffiliated withInstituto de Física, Sao Paulo University
  • , W. MaenhautAffiliated withInstitute for Nuclear Sciences, Rijksuniversiteit Gent

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Abstract

As a part of the FOS/DECAFE experiment, aerosol particles emitted during prescribed savanna fires were collected in January 1991 at Lamto (Ivory Coast), either close to the emission or in ambient air. Analytical transmission electron microscopy pointed out the presence of sub-micrometer soots, salt condensates, vegetation relicts and soil derived particles. The samples were also analyzed for their total particulate matter (TPM) content and elemental composition by PIXE or XRF. At the emission, high concentrations of soil derived elements (Fe and Al) pointed out an intense remobilization process during the fires. Biomass burning emissions contributed to more than 90% of the measured concentrations, of P, Cl, S, K, Cu and Zn, which were found primarily in the fine fraction with the exception of P. Near the emission, K was mainly present as KCl, evolving to K2SO4 in the ambient samples. Trace elements emission factors were obtained for the first time for the African savanna burning and their annual emissions were estimated: our median K emission factor (0.78 g/kg of C) is higher than estimates for other ecosystems (0.2–0.58 g/kg of C); Zn emissions (0.008 Tg/year) account for 4 to 11% of the global anthropogenic emissions.

Key words

biomass burning aerosols trace element flux emission factor savanna