Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
doi:10.5194/acp-2017-278
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
03 Apr 2017
Review status
This discussion paper is under review for the journal Atmospheric Chemistry and Physics (ACP).
Sub 500 nm refractory carbonaceous particles in the polar stratosphere
Katharina Schütze1,3, James C. Wilson2, Stephan Weinbruch1, Nathalie Benker1, Martin Ebert1, Ralf Weigel3, and Stephan Borrmann3,4 1Institut für Angewandte Geowissenschaften, Technische Universität Darmstadt, Darmstadt, Germany
2Department of Mechanical and Materials Engineering, University of Denver, Denver, CO 80208, USA
3Institut für Physik der Atmosphäre, Johannes Gutenberg-Universität, Mainz, Germany
4Partikelchemie, Max-Planck-Institut für Chemie, Mainz, Germany
Abstract. Eleven particle samples collected in the polar stratosphere during SOLVE (SAGE III Ozone loss and validation experiment) from January until March 2000 were characterized in detail by high-resolution transmission and scanning electron microscopy (TEM/SEM) combined with energy-dispersive X-ray microanalysis. A total number of 4175 particles (TEM = 3845; SEM = 330) was analyzed from these samples which were collected mostly inside the polar vortex in the altitude range between 17.3 and 19.9 km. By particle volume, all samples are dominated by volatile particles (ammonium sulfates/hydrogen sulfates). By number, approximately 28–82 % of the particles are refractory carbonaceous with sizes between 20–830 nm. Internal mixtures of refractory carbonaceous and volatile particles comprise up to 16 %, individual volatile particles about 9 to 72 %.

Most of the refractory carbonaceous particles are completely amorphous, a few of the particles are partly ordered with a graphene sheet separation distance of 0.37 ± 0.06 nm (mean value ± standard deviation). Carbon and oxygen are the only detected major elements with an atomic O / C ratio of 0.11 ± 0.07. Minor elements observed include Si, S, Fe, Cr and Ni with the following atomic ratios relative to C: Si / C: 0.010 ± 0.011; S / C: 0.0007 ± 0.0015; Fe / C: 0.0052 ± 0.0074; Cr / C: 0.0012 ± 0.0017; Ni / C: 0.0006 ± 0.0011 (all mean values ± standard deviation).

High resolution element distribution images reveal that the minor elements are distributed within the carbonaceous matrix, i.e., heterogeneous inclusions are not observed. No difference in size, nanostructure and elemental composition was found between particles collected inside and outside the polar vortex.

Based on chemistry and nanostructure, aircraft exhaust, volcanic emissions and biomass burning can certainly be excluded as source. The same is true for the less probable, but globally important sources: wood burning, coal burning, diesel engines and ship emissions.

Rocket exhaust and carbonaceous material from interplanetary dust particles remain as possible sources of the refractory carbonaceous particles studied. However, additional work is required in order to identify the sources unequivocally.


Citation: Schütze, K., Wilson, J. C., Weinbruch, S., Benker, N., Ebert, M., Weigel, R., and Borrmann, S.: Sub 500 nm refractory carbonaceous particles in the polar stratosphere, Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2017-278, in review, 2017.
Katharina Schütze et al.
Katharina Schütze et al.
Katharina Schütze et al.

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Short summary
Stratospheric particles were collected in the polar stratosphere during the SOLVE campaign in winter 1999/2000. Besides the well-studied volatile particles from that region, the main finding of this study are stable carbonaceous particles in the sub 500 nm size range. In addition to carbon, many particles show the elements Si, S, Fe, Cr and Ni to a minor amount. Based on source exclusion, rocket exhaust and carbonaceous material from interplanetary dust remain as possible sources.
Stratospheric particles were collected in the polar stratosphere during the SOLVE campaign in...
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