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 1

Description of deployed material and location of sample sites. (a) Deployment of the Delta Ray IRIS in the INGV Palermo laboratory. U.R.I.: Universal Reference Interface; Ref: reference gases (see text for explanations). (b) Delta Ray Xpand dilution system with the dilutor and the 5 fixed range dilution wires used in this study covering the full range of CO₂ content. (c) Location of the main field tests. Pressure tests were performed at 3 various altitudes (about 0, 1000, and 2000 m) on Mount Etna along the road with the Delta Ray IRIS embarked in an INGV Palermo car. The soil CO₂ test was performed at Passopisciaro with the Delta Ray IRIS deployed in a shed, less than 20 m far from the permanent soil CO₂ flux station of the EtnaGas network [42]. (d) Location of the sampling sites at Stromboli (P0, P2, and P6) where soil CO2 emissions were sampled within both Multi-Layer bags and Exetainer vials. (e) Deployment of the Delta Ray IRIS in the INGV Palermo car for the pressure tests. The power supply was provided by the car battery connected, adjusted with an inverter, and modulated with an Uninterruptible Power Supply (U.P.S.). (f) Deployment of the Delta Ray IRIS at Passopisciaro for semicontinuous measurements of soil CO₂ during 24 h. The power was provided by a 220 V home supply modulated with the U.P.S. Measurements were performed through a 5 m long stainless steel tubing connected to a 50 cm depth stainless steel probe to avoid adsorption of the CO₂ onto the internal tube [25].

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