Diffuse soil CO2 degassing from Linosa island

Herein, we present and discuss the result of 148 measurements of soil
CO2 flux performed for the first time in Linosa island (Sicily Channel,
Italy), a Plio-Pleistocene volcanic complex no longer active but still of interest
owing to its location within a seismically active portion of the Sicily
Channel rift system. The main purpose of this survey was to assess the
occurrence of CO2 soil degassing, and compare flux estimations from this
island with data of soil degassing from worldwide active volcanic as well
as non-volcanic areas. To this aim soil CO2 fluxes were measured over a
surface of about 4.2 km2 covering ~80% of the island. The soil CO2 degassing
was observed to be mainly concentrated in the eastern part of the
island likely due to volcano-tectonic lineaments, the presence of which is
in good agreement with the known predominant regional faults system.
Then, the collected data were interpreted using sequential Gaussian simulation
that allowed estimating the total CO2 emissions of the island.
Results show low levels of CO2 emissions from the soil of the island (~55
ton d-1) compared with CO2 emissions of currently active volcanic areas,
such as Miyakejima (Japan) and Vulcano (Italy). Results from this study
suggest that soil degassing in Linosa is mainly fed by superficial organic
activity with a moderate contribution of a deep CO2 likely driven by NWSE
trending active tectonic structures in the eastern part of the island.