Research Article

Recommendations and Protocols for the Use of the Isotope Ratio Infrared Spectrometer (Delta Ray) to Measure Stable Isotopes from CO2: An Application to Volcanic Emissions at Mount Etna and Stromboli (Sicily, Italy)

Figure 9

Time series of semicontinuous δ13C measurements from soil CO2 flux at Passopisciaro during 24 hours on January 29 and 30, 2019. (a) Comparison between molar CO2 content in soil measured with the Delta Ray IRIS (black) and from the permanent station of the EtnaGas network less than 20 m far. (b) Comparison between molar CO2 content in soil (black) and related δ13C values (red) measured with the Delta Ray IRIS. Comparison between δ13C values from soil CO2 (red) measured with the Delta Ray IRIS and (c) the air temperature (blue) and (d) the windspeed (green) from the Passopisciaro permanent station. (e) Plot of δ13C versus CO2 concentration obtained from soil CO2 using the Delta Ray IRIS. Magmatic end-member (; ) for Mount Etna, air values (; ), and biogenic end-member (; ) from [17, 24]. (f) Zoom of the plot of δ13C versus CO2 concentration. P1 (purple) for the period marked by air mixing in the probe. P2 (orange) for the night period. P3 (yellow) for the day period. “Anomalous” δ13C values during the P2 period diverging from the main air-biogenic mixing line highlighted with orange arrows.
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