Service interruption on Monday 11 July from 12:30 to 13:00: all the sites of the CCSD (HAL, Epiciences, SciencesConf, AureHAL) will be inaccessible (network hardware connection).
Skip to Main content Skip to Navigation
Journal articles

Monitoring CO2 concentration and δ13C in an underground cavity using a commercial isotope ratio infrared spectrometer

Abstract : CO2 stable carbon isotopes are very attractive in environmental research to investigate both natural and anthropogenic carbon sources. Laser-based isotope ratio infrared spectrometers (IRIS) allow in situ continuous monitoring of CO2 isotopes, and therefore they have a potential for unprecedented understanding of carbon sources and dynamics with a high temporal resolution. Here we present the performance assessment of a commercial IRIS analyzer, including the measurement setup and the data processing scheme that we used. Even if the analyzer performs 1-Hz measurements, an integration time of the order of 1 h is commonly needed to obtain acceptable precision for δ13C. The main sources of uncertainty on δ13C come from the concentration dependence and from the temporal instability of the analyzer. The method is applied to the in situ monitoring of the CO2 carbon isotopes in an underground cavity (Roselend Natural Laboratory, France) during several months. On a weekly timescale, the temporal variability of CO2 is dominated by transient contamination by human breath. Discarding these anthropogenic contaminations, CO2 and δ13C backgrounds do not show diurnal or seasonal fluctuations. A CO2 flux released into the tunnel by the surrounding rocks is measured. The carbon isotope composition of this CO2, identified with a Keeling plot, is consistent with a main production by microbial respiration and a minor production from weathering of carbonate minerals. The presented instrument and application study are relevant to cave monitoring, whether to understand CO2 dynamics in visited and/or painted caves for preservation purposes or to understand paleoclimate recording in speleothems.
Complete list of metadata
Contributor : Eva Fareau Connect in order to contact the contributor
Submitted on : Thursday, August 12, 2021 - 3:06:47 PM
Last modification on : Wednesday, October 27, 2021 - 3:51:34 PM
Long-term archiving on: : Saturday, November 13, 2021 - 6:43:29 PM


Publication funded by an institution


Distributed under a Creative Commons Attribution 4.0 International License




Sophie Guillon, Pierre Agrinier, Eric Pili. Monitoring CO2 concentration and δ13C in an underground cavity using a commercial isotope ratio infrared spectrometer. Applied Physics B - Laser and Optics, Springer Verlag, 2015, Field Laser Applications in Industry and Research 2014, 119 (1), pp.165-175. ⟨10.1007/s00340-015-6013-4⟩. ⟨insu-01448028⟩



Record views


Files downloads