Projekt

stable CO2 isotopes; laser spectroscopy; Lagrange transport model; regional characterization

Lead
Lay summary
The increase of carbon dioxide concentration in the earth's atmosphere is the dominating driver for global warming and climate change. Its ecological and economical impacts are widely recognized, and the quantification of the sources and sinks of 2CO is thus of great scientific, political and economical interest. CO2 concentration measurements alone are not sufficient to gain information about the gross exchange fluxes between the different carbon pools (ocean, biosphere and atmosphere) because they resemble net exchanges. However, individual fluxes are marked with specific isotopic 2CO signatures, which make the study of the stable CO2 isotope ratios (d13C-2CO and d18O-2CO) highly attractive. cycle and the corresponding models it would, however, be highly valuable to complement this information with 2 sources has mainly been performed on solid or liquid substrates, or in the gas phase close to the source. With respect to the global CO2To date, isotopic characterization of COseasonal and regional signatures of 2CO sources. Such large-scale, integrated information can be obtained from continuous, high-precision measurements performed at the high Altitude Research station Jungfraujoch, combined with state of the art Lagrangian transport simulations. One key element of this project is the long-term monitoring of d13C-2CO and d18O-2CO at a time scale of minutes, using a quantum cascade laser absorption spectrometer. This instrument has successfully been employed in several field campaigns, reaching a precision better than 0.05 ‰ in nearly unattended operation.

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Letzte Aktualisierung: 21.02.2013

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The increase of carbon dioxide concentration in the earth's atmosphere is the dominating driver for global warming and climate change. Its ecological and economical impacts are widely recognized, and the quantification of the sources and sinks of CO2 is thus of great scientific, political and economical interest. CO2 concentration measurements alone are not sufficient to gain information about the gross exchange fluxes between the different carbon pools (ocean, biosphere and atmosphere) because they resemble net exchanges. However, individual fluxes are marked with specific isotopic CO2 signatures, which make the study of the stable CO2 isotope ratios (d13C-CO2 and d18O-CO2) highly attractive.Isotope discrimination in d13C-CO2 is mainly driven by photosynthesis, and only to a minor extend by senescence, bacterial decomposition and respiration. Additional fractionation occurs through the transformation of organic material to fossil fuels. In contrast, d18O-CO2 in natural processes is largely governed by the isotope exchange between CO2 and water. Exchange fluxes of atmospheric CO2 with ocean water are high and drive d18O-CO2 towards zero on the VPDB-CO2 scale. However, oxygen exchange with leaf water (enriched in 18O) during photosynthesis and with ground water (depleted in 18O) during respiration modify the d18O-CO2 signature of the related CO2 sources.To date, isotopic characterization of CO2 sources has mainly been performed on solid or liquid substrates, or in the gas phase close to the source. With respect to the global CO2 cycle and the corresponding models it would, however, be highly valuable to complement this information with seasonal and regional signatures of CO2 sources. Such large-scale, integrated information can be obtained from continuous, high-precision measurements performed at the high Altitude Research station Jungfraujoch (46.548°N, 7.987°E, 3580 m a.s.l.) combined with state of the art Lagrangian transport simulations. One key element of this project is the long-term monitoring of d13C-CO2 and d18O-CO2 at a time scale of minutes, using a quantum cascade laser absorption spectrometer. This instrument has successfully been employed in several field campaigns, reaching a precision better than 0.05 ‰ in nearly unattended operation, without the need for liquid nitrogen.Competence in three strongly linked fields is combined within this project to reach its ambitious goals: isotope related climate research (Univ. Bern / M. Leuenberger), laser spectroscopy for isotope specific gas analysis (Empa / L. Emmenegger), and trajectory statistics and Lagrangian Particle Dispersion Models for source characterization (Empa / D. Brunner).