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
Received: 12 Jan 2015 – Discussion started: 04 Feb 2015
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.
Revised: 19 Jun 2015 – Accepted: 23 Jun 2015 – Published: 14 Jul 2015
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.
van Asperen, H., Warneke, T., Sabbatini, S., Nicolini, G., Papale, D., and Notholt, J.: The role of photo- and thermal degradation for CO2 and CO fluxes in an arid ecosystem, Biogeosciences, 12, 4161-4174, doi:10.5194/bg-12-4161-2015, 2015.