Near real-time isotopic measurements of CO2 sampled by drone at Stromboli, Italy
Abstract
Using a drone for sampling and two portable mass analyzers, we studied the carbon isotopic signature of CO2 in the plume of Stromboli volcano in Italy. Stromboli has multiple vents which can be sampled by drone, and the gas emitted is CO2-poor during quiescent degassing and CO2-rich during explosive degassing. During 12-17 May 2018 we sampled gases in the crater by a Turbo Ace Matrix-i quadcopter powered by two 22.2 volt 4.4 Ah lipo batteries, with a payload comprising a sampling system which included a Brailsford TD-3LS pump powered by a 9 volt dry cell battery and a series of 1 liter tedlar gas bags arranged in series. We flew the drone manually, with flight times of 10-12 minutes. After sampling, the gas bags were analyzed several hours later on the same day for δ13C and CO2 concentration by a Picarro G2201-i CRDS mass analyzer and a Thermo Delta Ray infrared spectrometer arranged sequentially. The drone samples from the plume exhibit low CO2 concentrations ranging from 405 to 490 ppm caused by dilution of the plume. The two instruments provide comparable results with no appreciable differences. Using a Keeling approach to deal with two-component mixing of the volcanic gas with the atmosphere, we calculated the isotopic composition of the volcanic gas as between -0.65 and -0.97‰ relative to V-PDB. This agrees well with IRMS measurements of plume gas collected on the ground in October 2010 which showed a CO2 range of 378-598 ppm and gave a Keeling intercept of -0.21‰ for the volcanic gas endmember. The obtained values are also consistent with the range of the δ13CCO2 values for fumarolic crater gases (between -2.8‰ and -1.5‰), and also CO2 extracted from fluid inclusions of olivine and clinopyroxene crystals separated from ultramafic cumulate xenoliths (-2.5‰ < δ13CCO2 <-1.0‰). Our plans are to improve the sampling system by (a) better controlling the pump by means of a remote on/off switch on the controller and (b) adding an electrochemical SO2 sensor which sends data remotely to the controller, so that we know when we are in high-concentration volcanic gas. These improvements should lead to enhanced CO2 concentrations and sampling resolution during our next mission to Stromboli in Fall 2018 or spring 2019.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.V23D0110S
- Keywords:
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- 8419 Volcano monitoring;
- VOLCANOLOGYDE: 8485 Remote sensing of volcanoes;
- VOLCANOLOGYDE: 8488 Volcanic hazards and risks;
- VOLCANOLOGYDE: 8494 Instruments and techniques;
- VOLCANOLOGY