Deep CO2 release revealed by stable isotope and diffuse degassing surveys at Vulcano (Aeolian Islands) in 2015–2018

The partitioning of carbon dioxide (CO2) released by soils at Vulcano Island (Aeolian Islands, Italy) was performed by combining the CO2 flux and the carbon isotope measurements. Based on this method, the amount of CO2 of volcanic origin was quantified six times during the period 2015–2018. The data analysis allowed us to establish the correlation between CO2 soil degassing and changes in the contribution of volcanic fluids. Carbon isotope determinations were performed in situ to enhance the coverage of data collection in space and time. These data were combined with both the CO2 contents in the ground gases and the soil CO2 flux. The amount of volcanic CO2 was distinguished from that of biogenic origin by implementing a three-component mixing model. The results of this study indicate that the increase in CO2 output in September 2018 reflects the increase in volcanic gas emissions. The measurement method and analysis presented in this work are sufficiently general to be applicable to the monitoring programs of active volcanoes.