EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Subsea Water Isotope Sensors: A novel tool for continuous and in-situ analysis

Roberto Grilli and Camillle Blouzon
Roberto Grilli and Camillle Blouzon
  • CNRS / Université Grenoble Alpes, Institut des Géosciences de l'Environnement (IGE), Saint-Martin-d'Hères, France (

The isotopic composition of seawater represents an important fingerprint of water masses, containing information about conditions during their formation and evolution. Following the spatial and temporal variability of either δD or δ18O of water in the ocean will provide a direct link to the freshwater cycle, allowing to discriminate between different water masses, such as the one coming from glacier and sea ice melting, freshwater rivers and precipitations.

Information from physical parameters (e.g. temperature and salinity) are not always enough for identifying the undergoing processes, and current knowledge of water isotopes or noble gases in the ocean remains very poor due to scarcity of measurements obtained from discrete sampling followed by laboratory analysis.

Here we present a novel in-situ Membrane Inlet Laser Spectroscopy (MILS) sensor which is currently under development. The sensor will provide simultaneous and continuous measurements of water isotopes (both δD and δ18O, expected precision of ~0.05‰) and will be adapted for deployment from vessels, through boreholes into the ice shelves, and to be integrated in autonomous underwater vehicles (AUVs). The instrument will run on batteries, with an autonomy of ~12h.

From 2021, the MILS sensor will be ready for field deployments, particular in the Southern Ocean, where high resolution water isotope data inside ice shelf cavities could be coupled with modelling approaches for better understanding the processes at work in ocean - ice shelf interactions, and better constraint the ice melting processes in Antarctica, which remains today a major challenge.

How to cite: Grilli, R. and Blouzon, C.: Subsea Water Isotope Sensors: A novel tool for continuous and in-situ analysis, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2984,, 2020

Display materials

Display file

Comments on the display material

AC: Author Comment | CC: Community Comment | Report abuse

Display material version 1 – uploaded on 24 Apr 2020
  • CC1: Comment on EGU2020-2984, Leo Middleton, 29 Apr 2020

    Hi Roberto, thanks so much for your presentation. I was wondering what the temporal resolution for your instrument would be? Are you hoping to be able to take measurements every minute or is that more a detail of the testing?

    • AC1: Reply to CC1, Roberto Grilli, 29 Apr 2020

      Hi, thanks for your comment. The measurement time will be limite by the so called "memory effect" of water molecules that interact with the wall of the gas sampling line and the measurement cell. We will try to minimize this time by applying an hydrophobic coatin, and according to some previeous testes we did, we should be able to reach a response time of few minutes. But this has to be tested.