First airborne samples of a volcanic plume for δ¹³C of CO₂ determinations

Volcanic degassing is one of the main natural sources of CO 2 to the atmosphere. Carbon isotopes of volcanic gases enable the determination of CO 2 sources including mantle, organic or carbonate sediments, and atmosphere. Until recently, this work required sample collection from vents followed by laboratory analyses. Isotope ratio infrared analyzers now enable rapid analyses of plume δ 13 C‐CO 2 , in situ and in real time. Here we report the first analyses of δ 13 C‐CO 2 from airborne samples. These data combined with plume samples from the vent area enable extrapolation to the volcanic source δ 13 C. We performed our experiment at the previously unsampled and remote Kanaga Volcano in the Western Aleutians. We find a δ 13 C source composition of −4.4‰, suggesting that CO 2 from Kanaga is primarily sourced from the upper mantle with minimal contributions from subducted components. Our method is widely applicable to volcanoes where remote location or activity level precludes sampling using traditional methods.