Determination of ultra-low oxygen concentrations in oxygen minimum zones by the STOX sensor.
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Revsbech, Niels Peter
Larsen, Lars Hauer
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The methods used until now have not been able to reliably resolve O2 concentrations in oceanic oxygen minimum zones below 1–2 µmol L−1. We present a new amperometric sensor for the determination of ultra‐low O2 concentrations under in situ conditions. The electrochemical STOX O2 sensor contains a primary sensing cathode and a secondary cathode that, when polarized, prevents entry of O2 into the sensor. This arrangement enables frequent in situ zero calibration and confers the sensor with a detection limit of 1‐10 nmol L−1 O2, even during application on a Conductivity‐Temperature‐Depth (CTD) profiler at great water depths. The sensor was used during the Galathea 3 Expedition to demonstrate that the core of the oxygen minimum zone (OMZ) off Peru contained < 2 nM O2. Application in a reactor on board demonstrated that changes in O2 concentrations in OMZ water containing < 200 nmol L−1 O2 could be monitored over periods of hours to days. The linear decrease in O2 concentration in the react.....
JournalLimnology and Oceanography Methods
Essential Ocean Variables (EOV)Oxygen
Maturity LevelTRL 8 Actual system completed and "mission qualified" through test and demonstration in an operational environment (ground or space)
Best Practice TypeStandard Operating Procedure
CitationRevsbech, N. P.; Larsen, L. H.; Gundersen, J.; Dalsgaard, T.; Ulloa, O. and Thamdrup, B. ( 2009) Determination of ultra‐low oxygen concentrations in oxygen minimum zones by the STOX sensor. Limnology and Oceanography Methods, 7, pp.371-381. DOI:10.4319/lom.2009.7.371.