Sub-Ocean: Subsea Dissolved Methane Measurements Using an Embedded Laser Spectrometer Technology

• DOI: 10.1021/acs.est.7b06171
• Publication Date: 2018-08-16T07:31:21Z
• Authors: Roberto Grilli; Jack Triest; Jérôme Chappellaz; Michel Calzas; Thibault Desbois; Pär Jansson; Christophe Guillerm; Bénédicte Ferré; Loïc Lechevallier; Victor Ledoux; Daniele Romanini
• Keywords: Trace gas; Subsea

We present a novel instrument, the Sub-Ocean probe, allowing in situ and continuous measurements of dissolved methane seawater. It relies on an optical feedback cavity enhanced absorption technique designed for trace gas coupled to patent-pending sample extraction method. The considerable advantage instrument compared with existing ones lies its fast response time order 30 s, that makes this probe ideal 3D-mapping water. could work up 40 MPa external pressure, it provides large dynamic range, from subnmol CH4 per liter seawater mmol L-1. In work, we laboratory calibration intercomparison standard method field results detection. good agreement headspace equilibration followed by gas-chromatography analysis supports utility accuracy instrument. A 620-m depth vertical profile Mediterranean Sea was obtained within only 10 min, indicates background values between 1 2 nmol L-1 below pycnocline, similar previous observations conducted different ocean settings. also reveals maximum at around 6 m depth, may reflect local production bacterial transformation organic matter.