Volcanic and hydrothermal areas are sites of intense diffuse soil degassing, largely contributing to natural emissions of greenhouse gases (GHGs) to the atmosphere. While deep magmatic and hydrothermal sources sustain the rise of CO2- and CH4-rich fluids towards the surface, the effective fraction of deep-sourced gases able to escape to the atmosphere through diffuse soil degassing is largely affected by secondary processes occurring at relatively shallow depths. Although posing challenges to life, hydrothermalized soils still harbor a variety of microbes (i.e. extremophiles) able to take advantage of the harsh conditions offered by solfataric fields. For instance, the occurrence of methanotrophic activity in soils from hydrothermal areas, documented by several authors, could virtually control and limit the emission of GHGs from volcanic and hydrothermal systems. In order to evaluate the impact of shallow biogeochemical processes on diffuse gas emissions, chemical and carbon (in CO2 and CH4) isotopic compositions of interstitial soil gases, as well as diffuse CO2 fluxes, from three hydrothermal systems in Italy (i. Solfatara Crater, Campi Flegrei; ii. Monterotondo Marittimo, Larderello geothermal field; iii. Baia di Levante, Vulcano Island) were investigated. Despite being characterized by a large supply of hydrothermal fluids, as indicated by soil CO2 fluxes up to 2400, 1920 and 346 g m-2 day-1, respectively, 13CO2 enrichments were recognized in interstitial soil gases with respect to fumarolic fluids, suggesting the occurrence of autotrophic CO2 fixation processes in the soil system. On the other hand, soil gases were enriched in 13CH4 and characterized by higher CO2/CH4 ratios with respect to those recorded in fumarolic discharges, pointing to the occurrence of CH4 consumption by methanotrophic activity, as supported by isotope fractionation modeling. The geochemical evidences confirmed the key role that methanotrophs play in regulating the release of GHGs from volcanic and hydrothermal environments.onments.
Clues on the potential role of microbial communities in mitigating greenhouse gas emissions from hydrothermal systems / Venturi S., Tassi F., Magi F., Cabassi J., Ricci A., Capecchiacci F., Caponi C., Nisi B., Vaselli O.. - ELETTRONICO. - (2020), pp. 199-199. (Intervento presentato al convegno 4a Conferenza A. Rittmann tenutosi a Catania nel 12-14 Febbraio 2020).
Clues on the potential role of microbial communities in mitigating greenhouse gas emissions from hydrothermal systems
Venturi S.
;Tassi F.;Magi F.;Cabassi J.;Ricci A.;Capecchiacci F.;Caponi C.;Nisi B.;Vaselli O.
2020
Abstract
Volcanic and hydrothermal areas are sites of intense diffuse soil degassing, largely contributing to natural emissions of greenhouse gases (GHGs) to the atmosphere. While deep magmatic and hydrothermal sources sustain the rise of CO2- and CH4-rich fluids towards the surface, the effective fraction of deep-sourced gases able to escape to the atmosphere through diffuse soil degassing is largely affected by secondary processes occurring at relatively shallow depths. Although posing challenges to life, hydrothermalized soils still harbor a variety of microbes (i.e. extremophiles) able to take advantage of the harsh conditions offered by solfataric fields. For instance, the occurrence of methanotrophic activity in soils from hydrothermal areas, documented by several authors, could virtually control and limit the emission of GHGs from volcanic and hydrothermal systems. In order to evaluate the impact of shallow biogeochemical processes on diffuse gas emissions, chemical and carbon (in CO2 and CH4) isotopic compositions of interstitial soil gases, as well as diffuse CO2 fluxes, from three hydrothermal systems in Italy (i. Solfatara Crater, Campi Flegrei; ii. Monterotondo Marittimo, Larderello geothermal field; iii. Baia di Levante, Vulcano Island) were investigated. Despite being characterized by a large supply of hydrothermal fluids, as indicated by soil CO2 fluxes up to 2400, 1920 and 346 g m-2 day-1, respectively, 13CO2 enrichments were recognized in interstitial soil gases with respect to fumarolic fluids, suggesting the occurrence of autotrophic CO2 fixation processes in the soil system. On the other hand, soil gases were enriched in 13CH4 and characterized by higher CO2/CH4 ratios with respect to those recorded in fumarolic discharges, pointing to the occurrence of CH4 consumption by methanotrophic activity, as supported by isotope fractionation modeling. The geochemical evidences confirmed the key role that methanotrophs play in regulating the release of GHGs from volcanic and hydrothermal environments.onments.
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