High-resolution, in situ measurement of dissolved CH4, d13CH4 and C2H6 at Lake Aiguebelette using a Membrane Inlet Laser Spectrometer

Description

Here, a continuous high-resolution dissolved CH4, d13CH4 and C2H6 measurements made with an in situ Membrane Inlet Laser Spectrometer instrument at lake Aigubelette on surface water (50 cm water depth) are reported. The measurements were performed on May 15th 2019 on the shallow areas in the southwest of the lake from near the shore to the islands in the center of the lake, then into the channel of Thiers at the lake outlet. The coordinates were provided by a Garmin 18x GPS unit with an accuracy of 15m. In the attached file we reported the local time (in hh:mm:ss and as fract time), the coordinates, the distance from shore in meter, the water depth in meter, the concentration of dissolved CH4 in mol fraction and in mol per liter of water, the concentration of dissolved C2H6 in mol fraction and the d13CH4 in permil. The data on the channel of Thiers were reported in a separated file. The accuracies of the measurements are +/-12% for the concentration of CH4 and C2H6 (limit of detection 0.06 ppm or 0.1 nmol L-1 for CH4, and 2 ppb 4 pmol L-1 for C2H6) and +/-2.2 permil for the d13CH4 . All uncertainties are expressed with a 2-sigma confidential interval. In the original files dissolved C2H6 concentrations were wrong, and have been corrected in the version V2.

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