Biodegradation of CO2, CH4 and volatile organic compounds (VOCs) in soil gas from the Vicano–Cimino hydrothermal system (central Italy)

Carbon isotopic signature of interstitial soil gases reveals the potential role of ecosystems in mitigating geogenic greenhouse gas emissions: Case studies from hydrothermal systems in Italy

“…A stainless-steel tube (inner diameter 0.4 cm) was inserted at 5 to 20 cm depth to collect interstitial soil gases. The tube was then connected, through a PTFE three-way valve, to a 60 mL plastic syringe used for pumping the gas from the tube, and to (i) a 12 mL glass vial, equipped with a pierceable rubber septum (Labco Exetainer®), for chemical analyses, and (ii) a 1 L Supelco's Tedlar® gas sampling bag, equipped with a push/pull lock valve, for isotopic analyses (Tassi et al, 2015a(Tassi et al, , 2015b. Soil temperature was determined by inserting a thermocouple in the soil down to the sampling depth.…”

“…Accordingly, methanotrophic activity in hydrothermal soils was inferred on the basis of geochemical tracers, such as soil CO 2 and CH 4 flux measurements and chemical and isotopic analysis of interstitial soil gases (e.g. Castaldi and Tedesco, 2005;D'Alessandro et al, 2009D'Alessandro et al, , 2011Tassi et al, 2015b).…”

Structural architecture releasing deep-sourced carbon dioxide diffuse degassing at the Caviahue – Copahue Volcanic Complex

“…Date Thermal site (i) gas diffusion through the soil (e.g. Cerling and Quade, 1993;Capasso et al, 1997Capasso et al, , 2001Di Martino et al, 2016;Etiope et al, 2009 and references therein;Federico et al, 2010;Kayler et al, 2010) and (ii) microbial CO 2 uptake processes (Tassi et al, 2015 and references therein; e.g. Freude and Blaser, 2016 and references therein) are able to produce an isotope fractionation effect resulting in an enrichment in 13 C in residual CO 2 .…”

A multi-instrumental geochemical approach to assess the environmental impact of CO2-rich gas emissions in a densely populated area: The case of Cava dei Selci (Latium, Italy)

“…While endogenous gas was adjectively discharged at F2 through the blowing well, diffusive transport process exerted a pivotal influence on the total output of endogenous gas at F1. Accordingly, the δ 13 C-CO 2 values measured at F1, which are slightly higher than those measured at F2 and those expected for a simple mixing between air and endogenous gas, were likely due to isotopic fractionation processes occurring in the soil layers in response to gas diffusion and microbial activity (Cerling et al, 1991;Capasso et al, 2001;Camarda et al, 2007;Federico et al, 2010;Tassi et al, 2015b).…”