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Sensors for Autonomous Ocean Observations

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Front. Mar. Sci. | doi: 10.3389/fmars.2018.00060

FIRST DEPLOYMENT AND VALIDATION OF IN SITU SILICATE ELECTROCHEMICAL SENSOR IN SEAWATER

 Carole BARUS1*, Dancheng Chen Legrand1, Nicolas Striebig2,  Benoit Jugeau3, Arnaud David3, Maria Valladares4, 5,  Praxedes Munoz Parra4, 5,  Marcel E. Ramos4, 5, Boris Dewitte1, 4 and Véronique Garçon1
  • 1UMR5566 Laboratoire d'études en géophysique et océanographie spatiales (LEGOS), France
  • 2Groupe d'Instrumentation Scientifique, UMS831 Observatoire Midi-Pyrénées (OMP), France
  • 3NKE Instrumentation (France), France
  • 4Centro de Estudios Avanzados en Zonas Áridas (CEAZA), Chile
  • 5Facultad de Ciencias del Mar, Catholic University of the North Antofagasta, Chile

An electrochemical sensor is proposed to measure silicate concentration, in situ, in the ocean without any addition of liquid reagent. From the analytical principle to the laboratory prototype toward the first in situ, immersible sensor, the evolution of the mechanical design is presented and discussed. The developed in situ electronics were compared to the commercial potentiostat and gave promising results to detect low silicate signals with a limit of quantification of 1 µmol L-1.The flow rate of the pump appeared to be a crucial parameter in order to transfer the silicomolybdic complex formed from the ‘complexation cell’ to the ‘detection cell’ without dilution as well as to fill and rinse the whole circuit. The study of temperature effect revealed no influence on the electrochemical signal between ~7°C and ~21°C. Finally the sensor was successfully deployed for the very first time on a mooring off Coquimbo, Chile and also integrated onto a PROVOR profiling float in the Mediterranean Sea off Villefranche-sur-Mer, France. The data collected and/or sent through satellite were in good agreement with the 2 reference samples and previously published values illustrating the great potential of this electrochemical sensor. A 7 days silicate time series from the mooring deployment off Chile is also presented.

Keywords: autonomous sensor, Reagentless electrochemical detection, Silicate, Seawater, Mooring & float deployments

Received: 25 Oct 2017; Accepted: 09 Feb 2018.

Edited by:

Douglas P. Connelly, National Oceanography Centre Southampton, United Kingdom

Reviewed by:

Moritz Holtappels, Alfred Wegener Institut Helmholtz Zentrum für Polar und Meeresforschung, Germany
Maxime M. Grand, University of Hawaii at Manoa, United States  

Copyright: © 2018 BARUS, Chen Legrand, Striebig, Jugeau, David, Valladares, Munoz Parra, Ramos, Dewitte and Garçon. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Carole BARUS, UMR5566 Laboratoire d'études en géophysique et océanographie spatiales (LEGOS), 18 avenue Edouard BELIN, Cedex 9, Toulouse, 31401, France, carole.barus@legos.obs-mip.fr