Field Continuous Measurement of Dissolved Gases with a CF-MIMS: Applications to the Physics and Biogeochemistry of Groundwater Flow

Abstract

In the perspective of a temporal and spatial exploration of aquatic environments (surface and groundwater), we developed a technique for field continuous measurements of dissolved gases with a precision better than 1% for N, O, CO, He, Ar, 2% for Kr, 8% for Xe, and 3% for CH, NO and Ne. With a large resolution (from 1 × 10 to 1 × 10 ccSTP/g) and a capability of high frequency analysis (1 measure every 2 s), 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, ionization) 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 involving the well-logging of dissolved gases and the implementation of groundwater tracer tests with dissolved He. The results demonstrate the analytical capabilities of the CF-MIMS in the field. Therefore, the CF-MIMS is a valuable tool for the field characterization of biogeochemical reactivity, aquifer transport properties, groundwater recharge, groundwater residence time and aquifer-river exchanges from few hours to several weeks experiments.

In situ observation of helium and argon release during fluid-pressure-triggered rock deformation

“…Our assessment demonstrates the ability of GE-MIMS technology to monitor fluid remobilization in response to in situ rock deformation. The temporal scales of the processes involved not only require a high-frequency monitoring system 24,32 but also a multi-tracer approach, i.e., He, Ar and N 2 in the case of the GTS. Complementing the findings of previous experiments performed in the laboratory [17][18][19][20] , as (2020) 10:6949 | https://doi.org/10.1038/s41598-020-63458-x www.nature.com/scientificreports www.nature.com/scientificreports/ well as those advanced from large-scale observations in the context of earthquakes 5 , we interpret these anomalies as the release of radiogenic He (and Ar) stored in the rock mass that could be transported within the newly created and pre-existing fracture system.…”

Dipole and Convergent Single-Well Thermal Tracer Tests for Characterizing the Effect of Flow Configuration on Thermal Recovery

“…Such vertical dipole configuration has already been developed in porous media for hydraulic and solute tracer tests to characterize the vertical hydraulic heterogeneity of porous aquifer [34][35][36]. In the present study, we choose this experimental setup since the excellent hydraulic connection between two fractures crossing the same borehole was confirmed thanks to previous tracer tests using dissolved helium and amino G acid [37]. As we targeted the two shallowest flowing fractures of the borehole (B3-1 and B3-2), localized thanks to previous hydraulic experiments [38], we did not isolate the upper fracture from the top part of the borehole.…”

Thermal Attenuation and Lag Time in Fractured Rock: Theory and Field Measurements From Joint Heat and Solute Tracer Tests

“…The possibility to choose the size of the chamber and the distance between injection and withdrawal leads to reduce transfer times. Few vertical tracer tests using helium as a tracer have been performed previously at the experimental site of Stang er Brune (France), and in the same single‐well dipole configuration (Chatton et al, ), showing the good connectivity of two permeable fractures crossing the same borehole at different depths. This setup can be compared to classical cross‐borehole tests, except that only one borehole is instrumented.…”

“…Hydraulic head measurements and previous solute tracer tests showed that these two fractures are hydraulically connected in the vicinity of the well. In particular, solute tracers can be transported from one fracture to the other in less than an hour for a pumping rate of 2 m 3 /hr (Chatton et al, ). According to optical and acoustic imaging borehole logs and caliper data, B3‐1 corresponds to a fractured zone located between 33.6‐ and 37.2‐m deep (Figures a, d, e).…”