Flux measurements of gaseous elemental mercury (GEM) from the geothermal area of “Le Biancane” natural park (Monterotondo Marittimo, Grosseto, Italy): Biogeochemical processes controlling GEM emission

Deep Regional Fluid Pathways in an Extensional Setting: The Role of Transfer Zones in the Hot and Cold Degassing Areas of the Larderello Geothermal System (Northern Apennines, Italy)

“…Amiata (Sbrana et al., 2020), Latera (Chiodini et al., 2007) and Torre Alfina (Carapezza et al., 2015). On the contrary, populations C, recognized at Sasso‐Monterotondo (Figure 4c), Monterotondo‐N (Figure 4d), and Monterotondo‐S (Cabassi et al., 2021), represent an endogenous CO 2 source, likely linked to magmatic outgassing and/or decarbonation processes of limestones, carbonates and calc‐silicates occurring in these areas (Gherardi et al., 2005). Eventually, given the intermediate mean values computed for populations B, generally comprised between ∼30 and ∼85 g m −2 day −1 , they can be related to mixing processes between biogenic and endogenous sources, or different transport mechanisms (i.e., diffusive or advective) as recognized in a specific area of Monterotondo‐N (Taussi et al., 2022).…”

“…Moving away from these areas, CO 2 output values of ∼28 (Lagoni‐Sasso) and ∼75 t d −1 km −2 (Sasso‐Monterotondo), being one order of magnitude lower than those of Monterotondo‐N and Sasso Pisano, are calculated. The Monterotondo‐S shows an intermediate value of ∼156 t d −1 km −2 (Cabassi et al., 2021).…”

“…Carbon dioxide flux data from the Monterotondo‐S area can be found in Cabassi et al. (2021). Carbon isotopic composition of the interstitial soil gases from the Monterotondo‐S area can be found in Venturi et al.…”

“…In the central areas and surroundings, the highest heat flux values of the Larderello geothermal area have been measured, reaching up to ∼1,000 mW m − 2 (Della Vedova et al, 2001), with soil temperatures reaching up to ∼98°C in correspondence with geothermal emergencies (Cabassi et al, 2021;Taussi et al, 2022). These conditions mainly occur along an NNE-striking fault zone, at least 5 km long, that runs from Monterotondo Marittimo to Sasso Pisano Granieri et al, 2023;Hooker et al, 1985;Leila et al, 2021;Minissale et al, 1997;Panichi & Tongiorgi, 1975;Tassi et al, 2012;Venturi et al, 2019) and geothermal wells (Gherardi et al, 2005;Magro et al, 2003); (c) dot-map of the Rc/Ra values measured in natural emissions (data from Hooker et al, 1985;Minissale et al, 1997;Magro et al, 2003) and geothermal wells (Gherardi et al, 2005;Hooker et al, 1985;Magro et al, 2003); (d) distribution of degassing rates computed in this work for central and peripheral areas.…”

“…In specific degassing areas, interstitial gas samples (n.77) for the determination of the δ 13 C-CO 2 values (expressed as ‰ vs. V-PDB-Vienna-Pee Dee Belemnite) were collected. In the Monterotondo Marittimo area (hereafter Monterotondo) previously published data by Venturi et al (2019) and Cabassi et al (2021), consisting of 35 interstitial CO 2 carbon isotopic composition and 89 measurements of CO 2 flux, respectively, carried out in the area named Monterotondo-S (Figure 3b) were also taken into account.…”