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Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Volume 12, issue 13
Biogeosciences, 12, 4161-4174, 2015
https://doi.org/10.5194/bg-12-4161-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
Biogeosciences, 12, 4161-4174, 2015
https://doi.org/10.5194/bg-12-4161-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 14 Jul 2015

Research article | 14 Jul 2015

The role of photo- and thermal degradation for CO2 and CO fluxes in an arid ecosystem

H. van Asperen1, T. Warneke1, S. Sabbatini2, G. Nicolini2,3, D. Papale2, and J. Notholt1 H. van Asperen et al.
  • 1Institute of Environmental Physics, University of Bremen, Otto-Hahn-Allee 1, Bremen, 28359, Germany
  • 2Department for Innovation in Biological, Agro-food and Forest Systems (DIBAF), University of Tuscia, via S. Camillo de Lellis s.n.c., 01100 Viterbo, Italy
  • 3Euro Mediterranean Centre on Climate Change (CMCC) – Impacts on Agriculture, Forests and Ecosystem Services (IAFES), via A. Pacinotti 5, 01100 Viterbo, Italy

Abstract. Recent studies have suggested the potential importance of abiotic degradation in arid ecosystems. In this study, the role of photo- and thermal degradation in ecosystem CO2 and CO exchange is assessed. A field experiment was performed in Italy using an FTIR-spectrometer (Fourier Transform Infrared) coupled to a flux gradient system and to flux chambers. In a laboratory experiment, field samples were exposed to different temperatures and radiation intensities.

No photodegradation-induced CO2 and CO fluxes of in literature suggested magnitudes were found in the field nor in the laboratory study. In the laboratory, we measured CO2 and CO fluxes that were derived from thermal degradation. In the field experiment, CO uptake and emission have been measured and are proposed to be a result of biological uptake and abiotic thermal degradation-production.

We suggest that previous studies, addressing direct photodegradation, have overestimated the role of photodegradation and observed fluxes might be due to thermal degradation, which is an indirect effect of radiation. The potential importance of abiotic decomposition in the form of thermal degradation, especially for arid regions, should be considered in future studies.

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Recent studies have suggested the potential importance of abiotic decomposition (photodegradation) in arid ecosystems. This study focuses on the measurement and understanding of abiotic fluxes. Photodegradation fluxes have not been observed. Thermal degradation fluxes were observed in the field (for CO) and in the laboratory (for CO2 and CO). Previous studies have potentially overestimated the role of photodegradation or misinterpreted thermal degradation fluxes as photodegradation fluxes.
Recent studies have suggested the potential importance of abiotic decomposition...
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