Field continuous measurement of dissolved gases with a CF-MIMS: Applications to the physics and biogeochemistry of groundwater flow
Résumé
In the perspective of a temporal and spatial exploration of aquatic environments (surface and ground water),
we developed a technique for precise field continuous measurements of dissolved gases (N2, O
2
, CO
2
, CH4,
N2O, H2, He, Ne, Ar, Kr, Xe). With a large resolution (from 1
10-9 to 1
10-2 ccSTP/g) and a capability of
high frequency analysis (1 measure every 2 seconds), the CF-MIMS (Continuous Flow Membrane Inlet Mass
Spectrometer) is an innovative tool allowing the investigation of a large panel of hydrological and biogeochemical
processes in aquatic systems.
Based on the available MIMS technology, this study introduces the development of the CF-MIMS (conception for
field experiments, membrane choices, ionisation) and an original calibration procedure allowing the quantification
of mass spectral overlaps and temperature effects on membrane permeability.
This study also presents two field applications of the CF-MIMS (Chatton et al, 2016) involving the well-logging of
dissolved gases and the implementation of groundwater tracer tests with dissolved 4He. The results demonstrate
the analytical capabilities of the CF-MIMS in the field. Therefore, the CF-MIMS is a valuable tool for the field
characterisation of biogeochemical reactivity, aquifer transport properties, groundwater recharge, groundwater
residence time and aquifer-river exchanges from few hours to several weeks experiments.
Eliot Chatton, Thierry Labasque, Je ́roˆme de La Bernardie, Nicolas Guihe ́neuf, Olivier Bour and Luc
Aquilina; Field Continuous Measurement of Dissolved Gases with a CF-MIMS: Applications to the Physics and
Biogeochemistry of Groundwater Flow; Environmental Science & Technology, in press, 2016.